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Background Alcohol, a widely abused drug, significantly diminishes life quality, causing chronic diseases and psychiatric issues, with severe health, societal, and economic repercussions. Previously, we demonstrated that non-voluntary alcohol consumption increases the opening of Cx43 hemichannels and Panx1 channels in astrocytes from adolescent rats. However, whether ethanol directly affects astroglial hemichannels and, if so, how this impacts the function and survival of astrocytes remains to be elucidated. Results Clinically relevant concentrations of ethanol boost the opening of Cx43 hemichannels and Panx1 channels in mouse cortical astrocytes, resulting in the release of ATP and glutamate. The activation of these large-pore channels is dependent on Toll-like receptor 4, P2X7 receptors, IL-1β and TNF-α signaling, p38 mitogen-activated protein kinase, and inducible nitric oxide (NO) synthase. Notably, the ethanol-induced opening of Cx43 hemichannels and Panx1 channels leads to alterations in cytokine secretion, NO production, gliotransmitter release, and astrocyte reactivity, ultimately impacting survival. Conclusion Our study reveals a new mechanism by which ethanol impairs astrocyte function, involving the sequential stimulation of inflammatory pathways that further increase the opening of Cx43 hemichannels and Panx1 channels. We hypothesize that targeting astroglial hemichannels could be a promising pharmacological approach to preserve astrocyte function and synaptic plasticity during the progression of various alcohol use disorders.
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Background Astrocytes Ca2+ signaling play a central role in the modulation of neuronal function. Activation of metabotropic glutamate receptors (mGluR) by glutamate released during an increase in synaptic activity triggers coordinated Ca2+ signals in astrocytes. Importantly, astrocytes express the Ca2+-dependent nitric oxide (NO)-synthe-tizing enzymes eNOS and nNOS, which might contribute to the Ca2+ signals by triggering Ca2+ influx or ATP release through the activation of connexin 43 (Cx43) hemichannels, pannexin-1 (Panx-1) channels or Ca2+ homeostasis modulator 1 (CALHM1) channels. Hence, we aim to evaluate the participation of NO in the astrocytic Ca2+ signaling initiated by stimulation of mGluR in primary cultures of astrocytes from rat brain cortex. Results Astrocytes were stimulated with glutamate or t-ACPD and NO-dependent changes in [Ca2+]i and ATP release were evaluated. In addition, the activity of Cx43 hemichannels, Panx-1 channels and CALHM1 channels was also analyzed. The expression of Cx43, Panx-1 and CALHM1 in astrocytes was confirmed by immunofluorescence analysis and both glutamate and t-ACPD induced NO-mediated activation of CALHM1 channels via direct S-nitrosylation, which was further confirmed by assessing CALHM1-mediated current using the two-electrode voltage clamp technique in Xenopus oocytes. Pharmacological blockade or siRNA-mediated inhibition of CALHM1 expression revealed that the opening of these channels provides a pathway for ATP release and the subsequent purinergic receptordependent activation of Cx43 hemichannels and Panx-1 channels, which further contributes to the astrocytic Ca2+ signaling. Conclusions Our findings demonstrate that activation of CALHM1 channels through NO-mediated S-nitrosylation in astrocytes in vitro is critical for the generation of glutamate-initiated astrocytic Ca2+ signaling.
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BACKGROUND:Connexin 43(Cx43),which is thought to be engaged in the gap junction process and build the structural groundwork for the development of direct material signaling channels between cells,is crucial for maintaining the homeostatic balance of tissue metabolism.Recent research,however,has revealed fresh information about its distinct hemichannel function and highlighted the significance of its subcellular localization and self-fragmentation for cellular physiological activities and pathological processes. OBJECTIVE:To systematically summarize the molecular characteristics and expression of Cx43 in a variety of cells,concentrate on the pathological and physiological roles of channel-dependent Cx43 and channel-independent Cx43,and investigate the potential value in disease treatment by reviewing the pertinent literature in the database. METHODS:The Chinese and English keywords were"gap junction,connexin 43(Cx43),hemichannel,channel-dependent Cx43,channel-independent Cx43,extracellular vesicles(EVs),mitochondria,GJA1-20k",which were searched in PubMed and CNKI.Finally,81 articles were selected for review. RESULTS AND CONCLUSION:(1)The canonical role of Cx43 is to form a gap junction channel.Channel-dependent Cx43 has primarily involved in disease physiopathological processes by directly constituting gap junction channels,but full attention should be paid to the issue of its structural and functional integrity.Adhesion is a crucial characteristic of gap junctions,which are strongly associated with barrier-like diseases.(2)The non-canonical role of Cx43 is non-gap junction channel-dependent effect.In addition to being localized at the plasma membrane,inner mitochondrial membrane,extracellular vesicle surface,and other structures,Cx43 hexamer has also been found to play a role in positive pro-inflammatory mechanisms,mitochondrial functional metabolism,and targeted uptake of extracellular vesicles in inflammatory diseases.Selective shortened segments control mitochondrial homeostasis by encouraging the polymerization of peri-mitochondrial actin and are involved in the targeted translocation of full-length Cx43 to intracellular structural domains.(3)The development of targeted medicines and the solving of issues like the mechanism of seed cell transformation in tissue engineering-based therapies are both made possible by these two categories of impacts.The interactions of various types of Cx43,however,are frequently not fully taken into account in some of the existing original studies,which confuses the overall characteristics and skews the results.(4)It is necessary to systematically frame the physiological characteristics of Cx43 in different forms and its potential mechanisms in various diseases,so as to provide a reference for the exploration of the Cx43 integrity mechanism and the diagnosis and treatment of multiple diseases.
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AIM:To investigate the effect of conditioned medium from hypoxia/reoxygenation(H/R)-treated rat cardiac fibroblasts(CFs)on gap junction between cardiomyocytes and determine whether its mechanism is related to matrix metalloproteinase 2(MMP2)activity.METHODS:(1)H9c2 cells were randomly divided into five groups:con-trol group,normal group,ARP-100 group,H/R group,and H/R+ARP-100 group.Scrape loading/dye transfer assay was used to assess the gap junction function.Western blot was used to detect the expression and phosphorylation levels of Cx43.Gelatin zymography assay was performed to measure MMP2 activity.(2)SD rats were randomly divided into control group,ARP-100 group,ischemia-reperfusion(I/R)group,and I/R+ARP-100 group,with 8 rats in each group.Micro-electrode array technology was used to record the type and duration of arrhythmia.Immunohistochemistry experiment was performed to assess expression levels and distribution of Cx43 in myocardial tissues.RESULTS:Compared with the con-trol group,the H/R group showed decreased protein expression of Cx43(P＜0.01),narrowed distance of lucifer yellow dif-fusion(P＜0.01),and increased MMP2 activity(P＜0.01).ARP-100 attenuated H/R-induced gap junction dysfunction(P＜0.05).The arrhythmia score was also reduced after perfusion with ARP-100(P＜0.01).CONCLUSION:H/R-treated rat CFs can inhibit gap junction between cardiomyocytes,and its mechanism may involve increased MMP2 activity.
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ObjectiveTo observe and compare the electrocardiogram index， myocardial morphology， and connexin 43 （Cx43） expression of two rat models of acute cerebral infarction （ACI） due to stasis combined with toxin complicated with cerebral-cardiac syndrome （CCS）， and to provide experimental evidence for the research on the occurrence mechanism of cardiac diseases induced by ACI and the clinical diagnosis and treatment of CCS. MethodSixty SPF-grade male SD rats were randomized into six groups （n=10）： normal ， syndrome of stasis combined with toxin induced by carrageenin combined with dry yeast （CA/Y）， multi-infarct induced by micro-embolism （ME）， middle cerebral artery occlusion （MCAO）， CA/Y+ME， and CA/Y+MCAO groups. The model of syndrome of stasis combined with toxin was established by intraperitoneal injection with carrageenan （CA） at 10 mg·kg-1 on the first day and subcutaneous injection with dry yeast （Y） suspension （2 mg·kg-1） on the second day of modeling. Twenty-four hours after the modeling of ACI， the electrocardiograms （ECGs） of rats in each group were collected and the number/percentage （%） of abnormal ECG was calculated. The infarct area of the brain was evaluated by 2，3，5-triphenyltetrazolium chloride （TTC） staining， and myocardial injury was assessed by hematoxylin-eosin （HE） staining. Immumohistochemical staining and Western blot were employed to determine the expression of Cx43 in the myocardium. ResultA certain number of rats in each model group presented abnormal ECG. Compared with the normal group and CA/Y group， CA/Y+MCAO group had the highest rate of abnormal ECG （P<0.01）. Compared with the normal， CA/Y， ME， and CA/Y+ME groups， the CA/Y+ME and CA/Y+MCAO groups showed decreased amplitudes of P-wave and T-wave， shortened P-R interval， and extended Q-T interval， which were particularly obvious in the CA/Y+MCAO group （P<0.05， P<0.01） and in accordance with the cerebral infarction area and pathological changes. The expression of Cx43 was up-regulated in both CA/Y+ME and CA/Y+MCAO groups， especially in the CA/Y+MCAO group （P<0.01）. ConclusionThe two rat models of ACI due to stasis combined with toxin complicated with CCS can be used to study the mechanism of heart diseases caused by cerebrovascular diseases and the therapeutic effects of Chinese medicines with the functions of resolving stasis and detoxifying. Moreover， the CA/Y+MCAO method has higher abnormal electrocardiogram rate， severer myocardial pathological injury， and higher expression of Cx43 protein. The models can be chosen according to specific experimental purpose.
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Objective: To observe the effects of electroacupuncture (EA) at Neiguan (PC6) on arrhythmia during acute myocardial ischemia-reperfusion and the expression of connexin 43 (Cx43) in rats. Methods: A total of 40 Sprague-Dawley male rats were used. Ten rats were randomly selected as the blank group, and the remaining 30 rats were randomly divided into a model group and an EA group, with 15 rats in each group. Before modeling, rats in the EA group received one session of EA intervention at bilateral Neiguan (PC6) for 30 min; the other groups were treated with the same grasping and anesthesia for 30 min without intervention. PowerLab physiological recorder was used to record electrocardiograph within 30 min of infarction. After the experiment, cardiac tissue and serum were collected from rats. Hematoxylin-eosin (HE) staining was used to observe the morphological changes of myocardial tissue in the ventricular infarction area of rats in each group. The expression of Cx43 protein in the myocardium of each group was detected by Western blotting (WB). Enzyme-linked immunosorbent assay (ELISA) was used to determine the activity of Na+-K+-ATPase in myocardial tissue and the serum content of endogenous digitalis-like factor (EDLF) in rats. Results: There was no statistical difference in arrhythmia score between the EA group and the model group, but the total duration and average duration of arrhythmia in the EA group were decreased (P<0.01). HE staining showed that compared with the blank group, myocardial cells in the model group were disorganized and seriously damaged. The pathological changes in the EA group were similar to those in the model group, but the damage was relatively minor. The results of WB showed that compared with the blank group, the Cx43 expression in myocardial tissue of the model group was decreased (P<0.01); compared with the model group, the Cx43 expression in the EA group was increased (P<0.01); compared with the blank group, the Na+-K+-ATPase activity in myocardial tissue of the model group was significantly decreased (P<0.01); compared with the model group, the Na+-K+-ATPase activity in the EA group was increased (P<0.01). ELISA results showed that compared with the blank group, the serum EDLF content in the model group was significantly increased (P<0.01); compared with the model group, the EDLF content in the EA group was decreased (P<0.01). Conclusion: EA at Neiguan (PC6) can delay and reduce the onset of arrhythmia during myocardial infarction in the rat model of myocardial ischemia-reperfusion. Its mechanism of action may be related to the regulation of the Cx43 expression in myocardial tissue, improvement of the activity of Na+-K+-ATPase in myocardial tissue, and increase in the content of serum EDLF.
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ObjectiveTo investigate the effect and mechanism of modified Shuyuwan （SYW） on hippocampal myelin sheath injury in vascular dementia （VD） model rats. MethodSixty male SD rats of SPF grade were randomly divided into sham operation group， model group， and high-， medium- and low-dose modified SYW groups， with 12 rats in each group. The VD model was induced by bilateral carotid artery ligation in rats of the groups except for those of the sham operation group. After modeling， rats were screened by the water maze test， followed by drug treatment by gavage. Specifically， rats in the modified SYW groups were treated with modified SYW at 10， 5， 2.5 g·kg-1·d-1， accordingly， and those in other groups were administered with the same amount of normal saline. After intragastric administration for 28 days， the spatial learning and memory abilities of rats were detected by the water maze test. The hippocampal neuron structure was observed by hematoxylin-eosin （HE） staining. The content of hippocampal tumor necrosis factor （TNF）-α， interleukin-6 （IL-6）， and glutamate （Glu） was observed by biochemical detection. The hippocampal expression of myelin basic protein （MBP）， astrocyte activation marker glial fibrillary acidic protein （GFAP）， and connexin 43 （Cx43） was detected by immunofluorescence detection. The myelin sheath structure in the hippocampus was observed by the electron microscope. The α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor （AMPAR） and Cx43 protein expression was detected by Western blot. ResultCompared with the sham operation group， the model group showed prolonged escape latency （P<0.01）， decreased times of crossing the original platform and percentage of target quadrant detention time （P<0.01）， disordered neuron structure in the hippocampal CA1 region， loose myelin sheath lamella with blurry edge， up-regulated expression levels of TNF-α， IL-6， and Glu in the hippocampal CA1 region， especially Glu （P<0.01）， reduced expression of AMPAR （P<0.01）， increased protein expression of p-AMPAR and Cx43 （P<0.01）， significantly dwindled protein expression of MBP in the myelin sheath， and enhanced fluorescence co-labeled by GFAP and Cx43. Compared with the model group， the modified SYW groups showed shortened escape latency （P<0.05）， increased times of crossing the original platform and percentage of target quadrant detention time （P<0.05）， closely arranged hippocampal neuron structure， denser myelin sheath lamella with clear edge， down-regulated expression levels of TNF-α， IL-6， and Glu in the hippocampal CA1 region， especially Glu （P<0.01）， up-regulated AMPAR （P<0.01）， reduced protein expression of p-AMPAR and Cx43， especially in the high-dose group （P<0.01）， significantly elevated protein expression of MBP in the myelin sheath， and weakened fluorescence co-labeled by GFAP and Cx43， especially in the high-dose group. ConclusionModified SYW can improve the learning and memory abilities of VD rats， and the mechanism may be related to the inhibition of Cx43 expression， reduction of the release of Glu， inhibition of AMPAR-mediated inflammatory response to reduce the production of astrocyte marker GFAP， and promotion of the expression of MBP protein to alleviate myelin injury.
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The major blinding eye diseases, such as keratitis, cataract, glaucoma, diabetic retinopathy, seriously threaten human health and affect the quality of patients' life. Connexin 43(Cx43), as the most common connexin in vertebrates, is widely distributed in eye tissues and is involved in physiological processes such as embryonic development, metabolic regulation, tissue homeostasis, as well as pathological processes such as inflammation, oxidative stress, epithelial-mesenchymal transition, vascular leakage, and angiogenesis. Cx43 plays an important role in the occurrence and development of various blinding eye diseases. This article will review its role in the pathogenesis of the above-mentioned blinding eye diseases and the advances in targeting Cx43 therapy.
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Objective @#To investigation of the interaction between interstitial cells of Cajal (ICCs) and connexin 43 ( Cx43) in bladder contraction and its significance．@*Methods @#Eighty male guinea pigs were randomly divided into blank control group，Glivec group，Gap27 group and Glivec + Gap27 group．Four groups of guinea pigs were per- fused with saline，Glivec，Gap 27，and Glivec + Gap 27 every morning for 2 months．Success of urodynamic testing model after 2 months．Bladder tissue was collected for an in vitro muscle strip test to detect muscle contraction in each group．Correlation between c-Kit and Cx43 was detected by immunofluorescence．The interaction between c- Kit and Cx43 in the bladder was further validated by qRT-PCR and Western blot．Ultrastructural changes in the muscle layer of the bladder were observed by electron microscopy. @*Results @#Urodynamics revealed increased blad- der compliance in the experimental group compared to the blank control group (P＜0. 05) ; bladder compliance increased in the Glivec + Gap27 group compared to the Glivec and Gap27 groups (P＜0. 01) ．In vitro muscle strip experiments revealed that the frequency and tone of bladder muscle strip contractions were lower in the experimental group compared to the blank control group (P＜0. 05) ，and that muscle strip contractions were weaker in the ex- perimental group after administration of acetylcholine (ACH) compared to the control group(P＜0. 05) ．Immuno- fluorescence showed that c-Kit was co-expressed with Cx43 on ICCs cells．qRT-PCR and Western blot suggested that the protein expression level and gene expression level of Cx43 in bladder tissues were lower after inhibition of c-Kit than in the blank control (P＜0. 05) ; after inhibition of Cx43，the protein expression level and gene expres- sion level of c-Kit in bladder tissues the levels of c-Kit protein expression and gene expression in bladder tissues were lower than those in the blank control group (P＜0. 05) ．Electron microscopy revealed that the mitochondrial structure of bladder smooth muscle was disrupted after simultaneous inhibition of c-Kit and Cx43．@*Conclusion@#Cx43 is expressed on bladder ICCs and the two may be jointly involved in regulating bladder contractile function ; the joint reduction of Cx43 and c-Kit may have disrupted the mitochondria of bladder smooth muscle，affecting its function and consequently bladder contractile function.
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Aim To study the role of Cx43 hemichannel in rats with acute incision pain. Methods Adult male rats were randomly divided into normal saline group(C group), incision pain group(I group), Gap19 group. Western blot was used to determine the expression of Cx43 and GFAP at 6 h, 3 d and 7 d after paw incision surgery of rats. The rats were intrathecal injected with Gap19 30 min before incision surgery, followed by the measurement of the paw withdrawal threshold to mechanical stimuli at several time points. Immunofluorescence was used to detect the expression of Cx43 and GFAP. ELISA was performed to detect the different inflammatory cytokine levels in rats after surgery. Results Compared with group C, the expression of Cx43 and GFAP of rats increased significantly 6 h after incision surgery in group I, while their expression at postoperative 3 d and 7 d showed no obvious alteration. Compared with the preoperative baseline, the mechanical paw withdrawal threshold in I group and Gap19 group rats was significantly reduced at 2 h, 6 h, 24 h and 3 d post-incision(P<0.01), but it had no obvious change on postoperative 7 d. Compared with group I, the mechanical paw withdrawal threshold in rats of Gap19 group increased 2 h, 6 h, 24 h post-incision, while it showed no statistical difference on 3 d and 7 d post-incision. Compared with group C, immunofluorescence results showed that the expression of GFAP and Cx43 in spinal cord dorsal horn astrocytes also increased significantly in Group I 6 h after incision surgery. Compared with group I, GFAP and the expression of Cx43 were markedly reduced in Gap19 group. There was no statistical difference on 7 d post-incision. Compared with those in group C, the inflammation factors including IL-1β, IL-6 and TNF-αobviously increased in group I. However, in contrary to the rats in group I, the rats pretreated with gap19 showed increased expression of Cx43 and GFAP in spinal cord dorsal horn. Conclusions Specific inhibition of Cx43 hemichannel significantly suppresses astrocyte activation and alters the inflammatory microenvironment in the spinal cord dorsal horn and reduces postoperative hyperalgesia in rats with acute incision pain.
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Connexin (Cx), a multigene-encoded transmembrane protein family, forms either gap junctions ( GJ) or hemichannels (HC) to mediate intercellular communication in plasma mem¬brane between adjacent cells or interacts with proteins by its car- boxyl terminal in the cytoplasm to participate in the process of tumor cell proliferation, apoptosis, necrosis, invasion, metasta¬sis, drug resistance and stem cell characteristics.However, mi- slocalization of Cx in cytoplasm or nucleus often occurs in many tumors, and involved in the occurrence and development of tumors.Subcellular localization of Cx is affected by post-transla- tional modifications, including phosphorylation, ubiquitination, and acetylation.In this paper the classification and function of Cx, the relationship between subcellular localization of Cx and tumorigenesis and the regulation of post-translational modifica¬tion on Cx are reviewed in order to provide new ideas for the study of Cx as a potential target for cancer therapy.
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Objective To stud)' the expression of connexin (Cx) 26 and Cx30 in the cochlea in rat model of type 2 diabetes, and their role in the hearing loss of type 2 diabetes. Methods Sixty wistar rats were randomly divided into a control group(re = 20) and a experimental group(re = 4 0) . Rats in the experimental group received intraperitoneally injection of 10 mg/L streptozotocin to establish model of type 2 diabetes. Auditory brainstem response (ABR) was tested before and after molding at month 1, 2, 3, 4, 5. The morphology of cochlea was observed by HE staining, and the level and pattern of Cx26 and Cx30 expression within the cochlea were detected by immunofluorescence and Western blotting. Results In rats in the diabetes group, wave IH and V latency, I -IH and I - V interval of Click-ABRs (60 dBSPL) prolonged at month 1, 2, 3, 4, 5 after molding compared to the control (P < 0 . 0 5) . The number of cells was obvious reduced in the spiral ligament and ganglion of the experimental group (P < 0. 0 5) . Immunofluorescence and Western blotting results showed decreased expression of Cx26 and Cx30 in the experimental group at 2, 3, 4, 5 month(P<0. 05), and the expression of the two proteins decreased gradually with the time extension. Conclusion Expression of Cx26 and Cx30 is reduced at the same time as the occurrence of hearing impairment in rat cochlea with type 2 diabetes.
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Objective To observe the effects of the intercellular gap junction (GJIC) composed of connexin 43(Cx43) in mesenchymal stem cells (MSCs) from different sources and their signals on the biological behavior of multiple myeloma (MM) lateral population cells (SP cells), and to explore its possible mechanism. Methods Mesenchymal stem cells (MSCs) from different sources were isolated and cultured. SP cells of MM cell line RPMI 8266 were sorted by flow cytometry. RT-PCR and Western blot were used to detect the expression of Cx43 gene and protein in MSCs, RPMI 8266 and SP cells from different sources. The effects of MSCs from different sources on SP cell cycle, Cx43 protein expression, colony formation ability in vitro, stem cell related gene expression, cytokine secretion and drug resistance were observed. Results There was no significant difference in morphology and phenotype between MM-MSCs and ND-MSCs. Both MM-MSCs and RPMI 8266 cells expressed a higher level of Cx43. Co-culture with MM-MSCs induced more SP cells to enter G0 phase (P<0.001). The expressions of c-myc, Kif4 and Sox2 genes in SP cells were significantly up-regulated, while the expression of Oct-4 gene was down-regulated. After adding α-GA, c-myc, Kif4 and Sox2 were down-regulated in varying degrees, but there was no significant difference. The expression of Cx43 was up-regulated by (31.00±2)% and (39.00±2)%, respectively. The colony formation ability in vitro was up-regulated, and the addition of α-GA could partially inhibit this effect. A small amount of c-myc, Kif4, Sox2 and Oct-4 genes were expressed in RPMI 8266. These genes were significantly up-regulated in SP cell subpopulation. MM-MSCs secreted high levels of interleukin (IL)-6. After co-culture with SP cells, the expressions of IL-6, IL-10 and TGF-β in the supernatant of MM-MSCs were up-regulated (P=0.0072, P=0.037). bFGF and IL-17 had no significant change. After adding α-GA, the levels of IL-6, IL-10 and TGF-β in the supernatant decreased. MM cells were sensitive to bortezomib (BTZ) induced apoptosis, but SP cells were less sensitive. Co-culture with MM-MSCs significantly reduced BTZ-mediated apoptosis. The addition of α-GA partially restored the sensitivity of MM cells to bortezomib. Conclusion MM-MSCs and multiple myeloma SP cells up-regulate the expression of Cx43 protein, form more GJIC, and promote the proliferation and drug resistance of SP cells by changing the cytokine secretion profile of MSCs, which may be one of the reasons for the recurrence of MM.
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Adipose tissue is a promising target for treating obesity and metabolic diseases. However, pharmacological agents usually fail to effectively engage adipocytes due to their extraordinarily large size and insufficient vascularization, especially in obese subjects. We have previously shown that during cold exposure, connexin43 (Cx43) gap junctions are induced and activated to connect neighboring adipocytes to share limited sympathetic neuronal input amongst multiple cells. We reason the same mechanism may be leveraged to improve the efficacy of various pharmacological agents that target adipose tissue. Using an adipose tissue-specific Cx43 overexpression mouse model, we demonstrate effectiveness in connecting adipocytes to augment metabolic efficacy of the β 3-adrenergic receptor agonist Mirabegron and FGF21. Additionally, combing those molecules with the Cx43 gap junction channel activator danegaptide shows a similar enhanced efficacy. In light of these findings, we propose a model in which connecting adipocytes via Cx43 gap junction channels primes adipose tissue to pharmacological agents designed to engage it. Thus, Cx43 gap junction activators hold great potential for combination with additional agents targeting adipose tissue.
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OBJECTIVE@#To explore whether the using of mimetic peptide Gap27, a selective inhibitor of connexin 43 (Cx43), could block the death of dopamine neurons and influence the expression of Cx43 in 6-hydroxydopamine (6-OHDA)-induced Parkinson's disease mouse models.@*METHODS@#Eighteen C57BL/6 mice were randomly divided into control group, 6-OHDA group and 6-OHDA+Gap27 group, with 6 mice in each group. Bilateral substantia nigra stereotactic injection was performed. The control group was injected with ascorbate solution, 6-OHDA group was injected with 6-OHDA solution, and 6-OHDA+Gap27 group was injected with 6-OHDA and Gap27 mixed solution. Immuno-histochemical staining was used to detect the number of dopamine neurons, quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of Cx43 messenger ribonucleic acid (mRNA), immuno-fluorescence staining was used to detect the distribution of Cx43 protein, the contents of Cx43 protein and Cx43 phosphorylation at serine 368 (Cx43-ps368) in mouse midbrain were detected by Western blot.@*RESULTS@#After injection of 6-OHDA, numerous dopamine neurons in substantia nigra died as Cx43 content increased, Cx43-ps368 content decreased. Mixing Gap27 while injecting 6-OHDA could reduce the number of death dopamine neurons and weaken the changes of Cx43 and Cx43-ps368 content caused by 6-OHDA. The number of tyrosine hydroxylase (TH) immunoreactive positive neurons in 6-OHDA group decreased to 27.7% ± 0.02% of the control group (P < 0.01); The number of TH immunoreactive positive neurons in 6-OHDA+Gap27 group was (1.64±0.16) times higher than that in 6-OHDA group (P < 0.05); The content of total Cx43 protein in 6-OHDA group was (1.44±0.07) times higher than that in 6-OHDA+Gap27 group (P < 0.05) while (1.68±0.07) times higher than that in control group (P < 0.01). In 6-OHDA group, the content of Cx43-ps368 protein and its proportion in total Cx43 protein were significantly lower than that in 6-OHDA+Gap27 group (P < 0.05).@*CONCLUSION@#In 6-OHDA mouse models, mimetic peptide Gap27 played a protective role in reducing the damage to substantia nigra dopamine neurons, which was induced by 6-OHDA. The overexpression of Cx43 protein might have neurotoxicity to dopamine neuron. Meanwhile, decreasing Cx43 protein level and keeping Cx43-ps368 protein level may be the protective mechanisms of Gap27.
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Animals , Mice , Connexin 43/pharmacology , Disease Models, Animal , Dopaminergic Neurons/metabolism , Mice, Inbred C57BL , Oxidopamine/metabolism , Parkinson Disease/metabolism , Peptides/pharmacology , Tyrosine 3-Monooxygenase/pharmacologyABSTRACT
Objective:To investigate the effects of dexmedetomidine on the myocardial electrical conduction velocity and the expression and distribution of connexin 43 (Cx43) in rats.Methods:Healthy adult Sprague-Dawley rats of both sexes, weighing 270-330 g, were used.Twelve isolated rat hearts successfully perfused in the Langendorff apparatus were divided into 2 groups ( n=6 each) using a random number table method: control group (group C) and dexmedetomidine group (group D). The hearts were perfused for 15 min with K-H solution, and then the hearts were continuously perfused for 30 min with 37 ℃ K-H solution in group C and with K-H solution containing dexmedetomidine 50 ng/ml in group D. Programmed electrical stimulation was performed after the end of perfusion, the activation latency was recorded, and the electrical conduction velocity of myocardial tissues was calculated, and then the left ventricular myocardial tissues were obtained for determination of the expression and distribution of myocardial Cx43 protein by immunohistochemistry method. Results:Compared with group C, the activation latency was significantly prolonged, the electrical conduction velocity was reduced, and the expression of Cx43 was down-regulated in group D ( P<0.05). Cx43 protein was mostly distributed in intercalated discs at both ends of cells in group C, and there was a tendency for the proteins localized at end-to-end contact sites of ventricular cardiomyocytes to localize at side-to-side contact sites, and the distribution was messy in group D. Conclusions:Dexmedetomidine causes arrhythmia probably through down-regulating the expression of Cx43 protein, changing its distribution, and reducing myocardial electrical conduction velocity in rats.
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Sepsis is the main cause of death in intensive care unit (ICU). Sepsis and septic shock seriously affect the prognosis of patients and increase the mortality and re-morbidity of patients. Early and timely intervention can reduce the mortality and recurrence rate of patients with sepsis. The occurrence of sepsis may be related to the phosphorylation of connexin 43 (Cx43), which needs to be realized through various signal pathways. The related sites of connexin 43 are phosphorylated through different signal pathways to achieve the precise regulation of sepsis, these sites may be related targets for the treatment of sepsis and provide a direction for accurate treatment of sepsis. This paper mainly analyzes the role of Cx43-related signal pathways such as protein kinase A (PKA), protein kinase C (PKC), mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) in the pathogenesis of sepsis.
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Objective:To investigate the effects of Connexin-43 (Cx43) on osteoblasts proliferation and osteogenic differentiation and its regulatory mechanism.Methods:Osteoblasts were isolated and cultured in vitro. The osteogenic activity of osteoblasts was detected by alizarin red staining and alkaline phosphatase (ALP) staining after dexamethasone treatment. The expression of Cx43, Runt-related transcription factor 2 (Runx2), ALP, collagen I type (COL-I) and proliferation-related proteins PCNA and CDK4 in osteoblasts were detected by Western-blot. The expressions of osteoblast proteins were detected by immunofluorescence staining. The proliferation of osteoblasts was detected by CCK8 assay. The lentivirus-mediated Cx43 gene overexpression plasmid (Lv-Cx43) was constructed and transfected into osteoblasts. The osteogenic activity and proliferation ability of osteoblasts were further detected by the above methods. Cx43 in osteoblasts was overexpressed by pretreating PD98059. The osteogenic activity and proliferation of Cx43 in overexpressed osteoblasts was detected by CCK8 and alizarin red staining.Results:The isolated osteoblasts have osteogenic differentiation ability. Compared with the control group, 1×10 -6 mol/L dexamethasone treatment could reduce the formation of calcium nodules in osteoblasts. With the increase of dexamethasone treatment duration, the protein expression of Cx43, Runx2, ALP and COL-I in osteoblasts decreased gradually, while the expression of PCNA, CDK4 and p-ERK1/2 decreased. The OD values of normal osteoblasts at 0, 1, 2, 3 and 4 d were 0.316±0.043, 0.891±0.623, 1.683±0.154, 2.315±0.721 and 2.891±0.323, respectively. However, The OD values of osteoblasts treated with dexamethasone were 0.376±0.021, 0.657±0.121, 1.124±0.285, 1.521±0.272, 1.987±0.584, respectively. OD values of dexamethasone treated osteoblasts were lower than those of normal group at 2, 3 and 4 days ( P<0.05). The relative expression levels of Cx43 mRNA in control group, Lv-NC group and Lv-Cx43 group were 0.541±0.086, 0.598±0.018 and 1.000±0.082, respectively. The mRNA expression level of Cx43 in Lv-Cx43 group was higher than that in control group and Lv-NC group ( P<0.05). The ratio of Cx43 protein band to the gray value of GAPDH band in control group, Lv-NC group and Lv-Cx43 group were 0.816±0.737, 0.738±0.643 and 1.145±1.101, respectively. The expression level of Lv-Cx43 was higher than that in control group and Lv-NC group ( P<0.05). The expressions of Runx2, ALP, COL-I mRNA and related marker proteins in Lv-Cx43 group were higher than those in control group and Lv-NC group ( P<0.05). The number of calcium nodules in the Lv-Cx43 group was significantly higher than that in the control group and Lv-NC group. The OD value of osteoblasts and the number of calcium nodules in Lv-Cx43+PD98059 group were significantly lower than those in Lv-Cx43 group ( P<0.05). Conclusion:The proliferation and differentiation ability of osteoblasts is significantly decreased after the treatment of dexamethasone with decreased expression of Cx43. Overexpression of Cx43 can promote the proliferation and osteogenic differentiation of osteoblasts, which may be regulated through the ERK1/2 pathway.
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Objective:To evaluate the effect of rat cardiac fibroblasts (RCF) on the expression of connexin43 (Cx43) in H9c2 cells during hypothermic hypoxia/reoxygenation.Methods:H9c2 cells cultured in vitro were divided into 4 groups ( n=12 each) using the random number table method: control group (group C), hypothermic hypoxia/reoxygenation group (group HHR), RCF co-culture group (group Co) and RCF co-culture plus hypothermic hypoxia/reoxygenation group (group Co+ HHR). Group C was incubated at 37℃ in 5% CO 2 + 95% air for 5 h. Group HHR was incubated at 4 ℃ in 5% CO 2 + 95% N 2 for 1 h and then at 37 ℃ in 5% CO 2 + 95% air for 4 h. In group Co and group Co+ HHR, H9c2 cells 0.3×10 5 cells/well were inoculated in the lower chamber and RCF 0.6×10 5 cells/well in the the upper chamber of a transwell ? culture dish.Group Co was incubated at 37 ℃ in 5% CO 2 + 95% air for 5 h. Group Co+ HHR was incubated at 4℃ in 95% N 2 + 5% CO 2 for 1 h, and then incubated at 37 ℃ in 5% CO 2 + 95% air for 4 h. The mortality rate of H9c2 cells was measured by trypan blue staining, the expression of Cx43 and extracellular signal-regulated protein kinases 1/2 (ERK1/2) by immunofluorescence, and the expression of Cx43, phosphorylated Cx43, ERK1/2 and phosphorylated ERK1/2 by Western blot. Results:Compared with group C, the mortality rate of H9c2 cells was significantly increased, the expression and phosphorylation of Cx43 were decreased, and the expression and phosphorylation of ERK1/2 were increased in group HHR ( P<0.05), and no significant change was found in the mortality rate of H9c2 cells or expression and phosphorylation of Cx43 and ERK1/2 in group Co ( P>0.05). Compared with group Co, the mortality rate of H9c2 cells was significantly increased, and the expression and phosphorylation of Cx43 and ERK1/2 were decreased in group Co+ HHR ( P<0.05). Compared with group HHR, the mortality rate of H9c2 cells was significantly increased, and the expression and phosphorylation of Cx43 and ERK1/2 were decreased in group Co+ HHR ( P<0.05). Conclusions:RCFs can decrease the expression and activity of Cx43 in H9c2 cells during hypothermic hypoxia/reoxygenation, and the mechanism may be related to the down-regulation of ERK1/2 expression and inhibition of ERK1/2 activity.
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Abstract Introduction Hearing loss etiology depends on the population studied as well as on the ethnicity and the socio-economic condition of the analyzed region. Etiological diagnosis contributes to the improvement of preventive measures and to the early identification of this deficiency. Objective To identify the etiological factors of hearing loss and its prevalence in a tertiary hospital in southern Brazil, to verify the frequency of mutations in GJB2 and GJB6 genes, and to correlate the degree of hearing loss with the etiological factors of deafness. Methods This prevalence study involved 140 children with bilateral sensorineural or mixed hearing loss. Medical history, physical examination, audiometry, and evoked auditory brainstem response were conducted. Imaging and genetic examinations were also performed. Results Etiologies and their prevalence were as follows: (a) indeterminate causes, 31.4%; (b) conditions related to neonatal period, 22.1%; (c) genetic, 22.1%; (d) auditory neuropathy, 10%; (e) other factors (cortical malformation, intracranial hemorrhage, and internal ear malformations), 7.9% and (f) congenital infections, 6.4%. Within the genetic cases, ten homozygous and seven heterozygotes of the 35delG mutation were identified, besides two cases of rare variants of GJB2: p.Try172* and p.Arg184Pro. One case with homozygosis of del(GJB6-D13S1830) was found. Regarding severity of hearing loss, in 78.6% of the cases the degree of hearing loss was profound and there were no significant differences when comparing between etiologies. Conclusion The number of indeterminate etiologies is still high and congenital CMV infection may be a possible cause of undiagnosed etiology for hearing loss. The predominance of etiologies related to neonatal conditions and infectious causes are characteristic of developing countries. The most prevalent mutation was 35delG, the main GJB2 gene, probably because of the European influence in the genotype of our population.
Resumo Introdução A etiologia da perda auditiva depende da população estudada, da etnia e da condição socioeconômica da região analisada. O diagnóstico etiológico contribui para o aprimoramento das medidas preventivas e para a identificação precoce dessa deficiência. Objetivos Identificar os fatores etiológicos da perda auditiva e sua prevalência em um hospital terciário do sul do Brasil, verificar a frequência de mutações nos genes GJB2 e GJB6 e correlacionar o grau da perda auditiva com os fatores etiológicos da deficiência auditiva. Método Este estudo de prevalência avaliou 140 crianças com perda auditiva neurossensorial bilateral ou mista. Foram submetidos a anamnese com histórico médico, exame físico, audiometria e potencial evocado auditivo de tronco encefálico. Exames de imagem e genéticos também foram feitos. Resultados As etiologias e sua prevalência foram as seguintes: (a) causas indeterminadas, 31,4%; (b) condições relacionadas ao período neonatal, 22,1%; (c) genética, 22,1%; (d) neuropatia auditiva, 10%; (e) outros fatores (malformação cortical, hemorragia intracraniana e malformações da orelha interna), 7,9% e (f) infecções congênitas, 6,4%. Entre os casos genéticos, foram identificados dez casos homozigotos e sete heterozigotos da mutação 35delG, além de dois casos de variantes raras do GJB2: p.Try172* e p.Arg184Pro. Foi encontrado um caso homozigoto da mutação del (GJB6‐D13S1830). Em relação à gravidade da perda auditiva, em 78,6% dos casos o grau da perda auditiva foi profundo e não houve diferenças significantes na comparação entre as etiologias. Conclusão O número de etiologias indeterminadas ainda é elevado e a infecção congênita por CMV pode ser uma possível causa de etiologia não diagnosticada para perda auditiva. A predominância das etiologias relacionadas às condições neonatais e às causas infecciosas são características de países em desenvolvimento. A mutação mais prevalente foi a 35delG e o principal gene foi o GJB2, provavelmente devido à influência europeia no genótipo de nossa população.