Nitric oxide and ion channels mediate L-cysteine-induced inhibition of colonic smooth muscle contraction.

Previous studies have suggested that L-cysteine regulates gut motility through hydrogen sulfide. However, the mechanisms involved in the L-cysteine-induced response have not been extensively studied. This study aimed to investigate the underlying mechanisms of action of L-cysteine on spontaneous contraction of rat colon. Longitudinal and circular muscle strips from rat middle colon were prepared to measure the spontaneous contractile activities of colon in an organ bath system. Whole-cell voltage-clamp techniques were applied to record the currents of L-type voltage-dependent Ca2+ channels (VDCCs) and voltage-gated K+ channels (Kv) in isolated smooth muscle cells (SMCs) from colon. L-cysteine inhibited the spontaneous contraction of longitudinal and circular muscle strips from the rat colon in a concentration-dependent manner. The inhibition induced by L-cysteine was significantly decreased by inhibitors of H2S synthesis (p < 0.05). Furthermore, the suppression induced by L-cysteine was partially attenuated by tetrodotoxin, L-NNA and glibenclamide (p < 0.05). Whole-cell voltage-clamp recordings showed that L-cysteine caused a remarkable reduction in the peak currents of VDCCs and significantly increased the membrane currents of Kv channels in isolated SMCs (p < 0.05). We concluded that L-cysteine inhibits the contractile activities of smooth muscle strips from the rat colon. The relaxation in response to L-cysteine may be in part mediated by a nitrergic pathway and by inhibiting the VDCCs in combination with a direct activation of the KV channels and KATP channels.

Pentapeptide PYRAE triggers ER stress-mediated apoptosis of breast cancer cells in mice by targeting RHBDF1-BiP interaction.

Reinforced cellular responses to endoplasmic reticulum (ER) stress are caused by a variety of pathological conditions including cancers. Human rhomboid family-1 protein (RHBDF1), a multiple transmembrane protein located mainly on the ER, has been shown to promote cancer development, while the binding immunoglobulin protein (BiP) is a key regulator of cellular unfolded protein response (UPR) for the maintenance of ER protein homeostasis. In this study, we investigated the role of RHBDF1 in maintaining ER protein homeostasis in breast cancer cells. We showed that deleting or silencing RHBDF1 in breast cancer cell lines MCF-7 and MDA-MB-231 caused marked aggregation of unfolded proteins in proximity to the ER. We demonstrated that RHBDF1 directly interacted with BiP, and this interaction had a stabilizing effect on the BiP protein. Based on the primary structural motifs of RHBDF1 involved in BiP binding, we found a pentapeptide (PE5) targeted BiP and inhibited BiP ATPase activity. SPR assay revealed a binding affinity of PE5 toward BiP (Kd = 57.7 µM). PE5 (50, 100, 200 µM) dose-dependently promoted ER protein aggregation and ER stress-mediated cell apoptosis in MCF-7 and MDA-MB-231 cells. In mouse 4T1 breast cancer xenograft model, injection of PE5 (10 mg/kg, s.c., every 2 days for 2 weeks) significantly inhibited the tumor growth with markedly increased ER stress and apoptosis-related proteins in tumor tissues. Our results suggest that the ability of RHBDF1 to maintain BiP protein stability is critical to ER protein homeostasis in breast cancer cells, and that the pentapeptide PE5 may serve as a scaffold for the development of a new class of anti-BiP inhibitors.

Role of Hydrogen Sulfide in the Development of Colonic Hypomotility in a Diabetic Mouse Model Induced by Streptozocin.

Hydrogen sulfide (H2S), a novel gasotransmitter, is involved in the regulation of gut motility. Alterations in the balance of H2S play an important role in the pathogenesis of diabetes. This study was conducted to investigate the role of H2S in the colonic hypomotility of mice with streptozotocin (STZ)-induced diabetes. A single intraperitoneal injection of STZ was used to induce the type 1 diabetes model. Male C57BL/6 mice were randomized into a control group and an STZ-treated group. Immunohistochemistry, Western blotting, H2S generation, organ bath studies and whole-cell patch clamp techniques were carried out in single smooth muscle cells (SMCs) of the colon. We found that STZ-induced diabetic mice showed decreased stool output, impaired colonic contractility, and increased endogenous generation of H2S (p < 0.05). H2S-producing enzymes were upregulated in the colon tissues of diabetic mice (p < 0.05). The exogenous H2S donor sodium hydrosulfide (NaHS) elicited a biphasic action on colonic muscle contraction with excitation at lower concentrations and inhibition at higher concentrations. NaHS (0.1 mM) increased the currents of voltage-dependent calcium channels (VDCCs), while NaHS at 0.5 mM and 1.5 mM induced inhibition. Furthermore, NaHS reduced the currents of both voltage-dependent potassium (KV) channels and large conductance calcium-activated potassium (BK) channels in a dose-dependent manner. These results show that spontaneous contraction of colonic muscle strips from diabetic mice induced by STZ was significantly decreased, which may underlie the constipation associated with diabetes mellitus (DM). H2S overproduction with subsequent suppression of muscle contraction via VDCCs on SMCs may contribute in part to the pathogenesis of colonic hypomotility in DM. SIGNIFICANCE STATEMENT: Hydrogen sulfide may exhibit a biphasic effect on colonic motility in mice by regulating the activities of voltage-dependent calcium channels and voltage-dependent and large conductance calcium activated potassium channels. H2S overproduction with subsequent suppression of muscle contraction via VDCCs may contribute to the pathogenesis of colonic hypomotility in diabetes mellitus.

Effects and underlying mechanisms of L-arginine on spontaneous muscle contraction of rat colon.

Arginine (Arg), as a basic amino acid, has been reported to be involved in regulation of gut motility. However, the evidence is limited and the underlying mechanism is not fully understood. Our study was conducted to investigate the effects of L-Arg on spontaneous contraction of the longitudinal muscle strip (LMS) of the rat colon and the relevant mechanisms. An organ bath system was used to detect the contractile force of the LMS. Whole-cell voltage-clamp techniques were applied to observe alterations in the currents of large conductance Ca2+-activated K+ (KCa) channels, voltage-dependent potassium (KV) channels, and L-type Ca2+ channels (LTCCs) in smooth muscle cells (SMCs) of the colon. We found that L-Arg within the physiological concentration had no effect on contraction of LMS, while 1 mM L-Arg significantly increased both the amplitude and frequency of LMS contractility. And the increase in force was mucosa-dependent, whereas changes in frequency as well as in amplitude were inhibited by atropine. In addition, L-Arg (1 mM) activated the LTTCs and inhibited both KCa channels and KV channels on SMCs. Thus, L-Arg above the physiological concentration exerted an excitatory effect on colonic LM contraction, and stimulation by L-Arg was mediated by ACh. In addition, LTCCs, KCa channels, and KV channels on SMCs were involved in the action of L-Arg.

Adherent-invasive Escherichia coli LF82 aggravated intestinal inflammation in colitis mice by affecting the gut microbiota and Th17/Treg cell differentiation balance.

The imbalance of Th17 and Treg cell differentiation, intestinal flora imbalance, and intestinal mucosal barrier damage may be important links in the occurrence and development of inflammatory bowel disease (IBD) since Th17 and Treg differentiation are affected by the intestinal flora. This study aimed to explore the effect of Escherichia coli (E. coli) LF82 on the differentiation of Th17 and Treg cells and the role of the intestinal flora in mouse colitis. The effects of E. coli LF82 infection on intestinal inflammation were evaluated by analyzing the disease activity index, histology, myeloperoxidase activity, FITC-D fluorescence value, and claudin-1 and ZO-1 expression. The effects of E. coli LF82 on the Th17/Treg balance and intestinal flora were analyzed by flow cytometry and 16S rDNA sequencing. Inflammatory markers, changes in the intestinal flora, and Th17/Treg cells were then detected after transplanting fecal bacteria from normal mice into colitis mice infected by E. coli LF82. We found that E. coli LF82 infection can aggravate the intestinal inflammation of mice colitis, destroy their intestinal mucosal barrier, increase intestinal mucosal permeability, and aggravate the imbalance of Th17/Treg differentiation and the disorder of intestinal flora. After improving the intestinal flora imbalance by fecal bacteria transplantation, intestinal inflammation and intestinal mucosal barrier damage were reduced, and the differentiation balance of Th17 and Treg cells was restored. This study showed that E. coli LF82 infection aggravates intestinal inflammation and intestinal mucosal barrier damage in colitis by affecting the intestinal flora composition and indirectly regulating the Th17 and Treg cell differentiation balance.

The excitatory effect of hydrogen sulfide on rat colonic muscle contraction and the underlying mechanism.

H2S is a well-known relaxant regulator in muscle contraction but little attention has been paid to its excitatory effect on colonic motility. To investigate the excitation of H2S on rat colonic contraction and the underlying mechanism, the muscle contractile activity was assessed by an organ bath system, the level of substance P (SP) in the colon was detected using enzyme immunoassay kits, L-type Ca2+ channel currents (ICa,L) and large conductance Ca2+-activated K+ channel currents (IBK) in smooth muscle cells (SMCs) were measured by patch-clamp electrophysiology. The results show that the H2S donor NaHS (100 µM) reversed the relaxation of the NO donor SNP on colonic muscle contraction. Pretreatment with the TRPV1 antagonist and the neurokinin receptor antagonists attenuated the NaHS-induced excitation. Incubation of colon with NaHS increased the SP level. In freshly isolated SMCs, NaHS exerted a biphasic effect on ICa,L and concentration-dependently inhibited the IBK. And 100 µM NaHS partially reversed the SNP-induced changes in ICa,L and IBK. We concluded that exogenous H2S exerts a potential excitatory effect on colonic motility, which may be achieved by activating SP release from afferent nerves in combination with a direct activation of ICa,L and suppression of IBK in SMCs.

Knockdown of TRIM15 inhibits the proliferation, migration and invasion of esophageal squamous cell carcinoma cells through inactivation of the Wnt/ß-catenin signaling pathway.

TRIM15 is a member of tripartite motif-containing protein (TRIM) protein family, which plays important roles in several cancers. The aim of the present study was to evaluate the role of TRIM15 in esophageal squamous cell carcinoma (ESCC). Our results showed that TRIM15 was upregulated in human ESCC tissues and cell lines. In vitro studies showed that knockdown of TRIM15 significantly inhibited the proliferation, migration, and invasion of ESCC cells. Knockdown of TRIM15 caused a significant increase in E-cadherin expression, as well as decreases in expression of N-cadherin and Vimentin proteins. Moreover, in vivo assay proved that tumor growth was suppressed by knockdown of TRIM15. Furthermore, the protein expression levels of ß-catenin, C-myc, and CyclinD1 were markedly decreased in sh-TRIM15-infected ESCC cells. Additionally, treatment with LiCl reversed the inhibitory effects of TRIM15 knockdown on ESCC cells. In conclusion, these findings indicated that knockdown of TRIM15 blocked the growth and metastasis of ESCC in part through inhibiting the Wnt/ß-catenin signaling pathway. Thus, TRIM15 might serve as a promising therapeutic target for ESCC.

[Effect of L-cysteine on colonic motility and the underlying mechanism].

The purpose of the present study is to investigate the effect of L-cysteine on colonic motility and the underlying mechanism. Immunohistochemical staining and Western blot were used to detect the localization of the H2S-generating enzymes cystathionine-ß-synthase (CBS) and cystathionine-γ-lyase (CSE). Organ bath system was used to observe the muscle contractile activities. Whole-cell patch-clamp technique was applied to record ionic channels currents in colonic smooth muscle cells. The results showed that both CBS and CSE were localized in mucosa, longitudinal and circular muscle and enteric neurons. L-cysteine had a dual effect on colonic contraction, and the excitatory effect was blocked by pretreatment with CBS inhibitor aminooxyacetate acid (AOAA) and CSE inhibitor propargylglycine (PAG); L-cysteine concentration-dependently inhibited L-type calcium channel current (ICa,L) without changing the characteristic of L-type calcium channel (P < 0.01); In contrast, the exogenous H2S donor NaHS increased ICa,L at concentration of 100 µmol/L, but inhibited ICa,L and modified the channel characteristics at concentration of 300 µmol/L (P < 0.05); Furthermore, L-cysteine had no effect on large conductance calcium channel current (IBKCa), but NaHS significantly inhibited IBKCa (P < 0.05). These results suggest that L-cysteine has a potential dual effect on colonic smooth muscle and the inhibitory effect might be directly mediated by L-type calcium channel while the excitatory effect might be mediated by endogenous H2S.

[IL-6 inhibits colonic longitudinal muscle contraction by inactivating L-type calcium channel in rats with pancreatitis].

The aim of this study was to investigate the effect of interleukin 6 (IL-6) on the contraction of colon longitudinal muscle strips in rats with acute pancreatitis (AP) and its underlying mechanism. Rat AP model was established by combined injection (i. p.) of ceruletide and lipopolysaccharide. The effect of IL-6 on spontaneous contraction of longitudinal smooth muscle strips of rat colon was observed by biological function experiment system. The level of serum IL-6 was detected by ELISA, the expression and distribution of IL-6 in colon were observed by histochemical staining, and the effect of IL-6 on L-type calcium channel in colon smooth muscle cells was observed by whole cell patch clamp technique. The results showed that, compared with the control group, AP group exhibited reduced contractile amplitude and longer contraction cycle of colon smooth muscle strips. IL-6 prolonged the contraction cycle of colon smooth muscle strips, but did not affect their spontaneous contraction amplitude. Serum IL-6 concentration in AP group was significantly higher than that in control group (P > 0.05). IL-6 was diffusely distributed in the colon of the control group, but the expression of IL-6 was significantly up-regulated in the colon gland, mucosa and submucosa of the AP group. IL-6 significantly decreased the peak current density of L-type calcium channel in rat colon smooth muscle cells. These results suggest that the colon motility of AP rats is weakened, and the mechanism may be that up-regulated IL-6 inactivates L-type voltage-dependent calcium channels, and then inhibits the contraction of colon longitudinal smooth muscle.

Diallyl trisulfide regulates rat colonic smooth muscle contractions by inhibiting L-type calcium channel currents.

Diallyl trisulfide (DATS) is an active organosulfide component of allicin and has several beneficial effects, including antimicrobial, antioxidant, cardioprotective and anticancer effects. Few studies have shown the modulatory effect of DATS on L-type calcium channels in rat colonic smooth muscle cells and colonic motility. To investigate the modulatory effect of DATS on L-type calcium channels in rat colonic smooth muscle and colonic contraction, L-type calcium channel currents were recorded, and colonic contractility in longitudinal and circular smooth muscle strips was measured. DATS attenuated L-type calcium channel currents without affecting steady-state activation or inactivation kinetics and inhibited the spontaneous contractions of both longitudinal and circular smooth muscle strips dose-dependently. In conclusion, DATS has an inhibitory effect on the contractions of colonic muscle strips that is related to its regulation of L-type calcium channels.

Brain-Derived Neurotrophic Factor Contributes to Colonic Hypermotility in a Chronic Stress Rat Model.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) has prokinetic effects on gut motility and is increased in the colonic mucosa of irritable bowel syndrome. AIMS: We aimed to investigate the possible involvement of BDNF in stress-induced colonic hypermotility. METHODS: Male Wistar rats were exposed to daily 1-h water avoidance stress (WAS) or sham WAS for 10 consecutive days. The presence of BDNF and substance P (SP) in the colonic mucosa was determined using enzyme immunoassay kits. Immunohistochemistry and western blotting were performed to assess the expression of BDNF and its receptor, TrkB. The contractions of muscle strips were studied in an organ bath system. RESULTS: Repeated WAS increased the fecal pellet expulsion and spontaneous contractile activities of the colonic muscle strips. Both BDNF and SP in the colonic mucosa were elevated following WAS. Immunohistochemistry revealed the presence of BDNF and TrkB in the mucosa and myenteric plexus. BDNF and TrkB were both up-regulated in colon devoid of mucosa and submucosa from the stressed rats compared with the control. BDNF pretreatment caused an enhancement of the SP-induced contraction of the circular muscle (CM) strips. TrkB antibody significantly inhibited the contraction of the colonic muscle strips and attenuated the excitatory effects of SP on contractions of the CM strips. Repeated WAS increased the contractile activities of the CM strips induced by SP after BDNF pretreatment, and this effect was reversed by TrkB antibody. CONCLUSIONS: The colonic hypermotility induced by repeated WAS may be associated with the increased expression of endogenous BDNF and TrkB. BDNF may have potential clinical therapeutic use in modulating gut motility.

[Actions of endogenous hydrogen sulfide on colonic hypermotility in a rat model of chronic stress].

The present study was designed to investigate the potential role of endogenous hydrogen sulfide (H2S) in chronic stress-induced colonic hypermotility. Male Wistar rats were submitted daily to 1 h of water avoidance stress (WAS) or sham WAS (SWAS) for 10 consecutive days. The total number of fecal pellets was counted at the end of each 1 h of WAS or SWAS session. Organ bath recordings were used to test the colonic motility. H2S production of colon was determined, and immunohistochemistry and Western blot were performed on rat colonic samples to detect the distribution and expression of H2S-producing enzymes. The results showed that i) repeated WAS increased the number of fecal pellets per hour and the area under the curve (AUC) of the spontaneous contractions of colonic strips (P < 0.05), ii) repeated WAS decreased the endogenous production of H2S and the expression of H2S-producing enzymes in the colon devoid of mucosa and submucosa (P < 0.001), iii) cystathionine-γ-lyase (CSE) was strongly expressed in the cytosols of the circular and longitudinal smooth muscle cells and the nucleus of the myenteric plexus neurons, iv) cystathionine-ß-synthase (CBS) was primarily localized in the cytosols of myenteric plexus neurons and weakly localized in the epithelial cells and v) inhibitors of H2S-producing enzymes increased the contractile activity of colonic strips in the SWAS rats (P < 0.001). In conclusion, the results suggest that the colonic hypermotility induced by repeated WAS may be associated with the decreased production of endogenous H2S.

[Modulatory role and mechanism of BDNF and its receptor TrkB in colonic motility disorder in chronic stress rat].

OBJECTIVE: To investigate the role and mechanism of BDNF and its receptor TrkB in the disorder of colonic motility in chronic stress rats. METHODS: A total of 20 male Wistar rats were randomly divided into two groups using to completely random method after weighed, with 10 rats in each group. Chronic water avoidance stress model was established. Then the fecal pellets of water avoidance stress (WAS) group and sham water avoidance stress (SWAS) group were recorded. Enzyme linked immunosorbent assay (ELISA), real time PCR, Western blot and immunohistochemistry were used to detect the expression of BDNF and TrkB in serum and colon muscle. The amplitudes of contractions of circular smooth muscle strips of each group were recorded after the treatment of TTX, BDNF and K252a. RESULTS: The number of fecal pellets had obviously increased in WAS group comparing with SWAS group (P < 0.05). The level of serum BDNF in WAS group was higher than that of SWAS group ((158.30 ± 9.82) vs (84.68 ± 7.80) pg/ml). And the expression of TrkB in the colon muscle in WAS group was higher than that in SWAS group (0.44 ± 0.03 vs 0.30 ± 0.02, P < 0.05). There was no significant difference between the two groups in expression of BDNF mRNA in colon muscle (P > 0.05). TrkB was mainly expressed in the cell nucleus of muscular layer neurons, and the expression of TrkB had obviously increased in WAS rats. The amplitudes of contractions of circular smooth muscle in WAS rats had significantly increased compared with SWAS rats ((0.35 ± 0.02) vs (0.22 ± 0.03) g, P < 0.05). After adding TTX to block the function of enteric nervous, the difference was remaining ((0.89 ± 0.07) vs (0.53 ± 0.06) g, P < 0.05). BDNF was added to the bath and the R value at different time was recorded. The difference had statistically significant at 6 min and 12 min (both P < 0.05). BDNF could induced the contraction peak of the circular smooth muscle. The contraction peak induced by BDNF was delayed and reduced when K252a was added to the bath 30 min before adding BDNF. CONCLUSION: BDNF plays a modulatory role in the disorder of colonic motility in chronic stress rat by acting on its receptor TrkB.

[Effect of substance P on the potassium and calcium currents of colonic smooth muscle cells].

OBJECTIVE: To investigate the effect of substance P(SP) on the spontaneous contractile activity of smooth muscle cells,the large-conductance calcium-activated potassium channel currents (IBKCa) and the L-type calcium channel currents (ICaL) in rat smooth muscle cells of the proximal colon. METHODS: A total of 24 healthy male Wista rats were used in this test. The change of smooth muscle strips spontaneous contraction of rat proximal colon after adding SP was recorded by a physiological signal stystem (RM6240). The IBKCa and ICaL were measured via the whole cell patch-clamp technique. RESULTS: The longitudinal muscle contraction was obviously increased concentration-dependently after adding different concentrations of SP (10(-7)-10(-6) mol/L), so as the circular muscle while adding SP(10(-8)-10(-6) mol/L) (all P<0.05). Compared with the control group, IBKCa was decreased after adding SP(10(-6) mol/L). Under the stimulating voltage of 60 mV, the IBKCa current density was (11.71±1.65) pA/pF, which was significantly lower compared with the control group (14.42±2.89) pA/pF (P<0.05). The ICaL) was apparently increased. Under the stimulating voltage of 0 mV, the ICaL) currents density was (-5.04±0.67) pA/pF, compared with the control group (-4.25±0.46) pA/pF, which was significantly increased (P<0.01). CONCLUSIONS: SP can promote the spontaneous contractile activity of colon smooth muscle of rats in vitro.And SP decrease IBKCa representatively while apparently increase ICaL). That is probably one of the mechanism SP regulate the gastrointestinal motility.

[Effects of hydrogen sulfide on colonic contraction of rats and ion channel mechanisms].

OBJECTIVE: To explore the effects of hydrogen sulfide (H2S) on colonic contraction of rats at low concentration and ion channel mechanisms. METHODS: Organ bath recordings were used to examine the contraction of colonic smooth muscle strips. The whole-cell patch-clamp technique was used to record the currents of L-type calcium and large conductance Ca²âº-activated K⁺ (BKCa) channels in smooth muscle cells isolated from 30 male Wistar rats. RESULTS: The H2S donor NaHS ((1-12) × 10⁻5 mol/L) increased the spontaneous contractions of longitudinal and circular muscle strips in a dose-dependent manner (all P<0.05) and the effect could not be blocked by tetrodotoxin. NaHS (6 × 10⁻5 and 12 × 10⁻5 mol/L) reversibly increased the L-type calcium current (ICa,L) in a dose-dependent manner. And the peak of ICa,L at 0 mV increased from (-3.16 ± 0.47) to (-3.33 ± 0.54) and (-3.65 ± 0.66) pA/pF respectively (n=6, both P<0.05). Current-voltage (I-V) curve had no shift after NaHS treatment and H2S donor caused no change in the curves of steady-state activation. Likewise BKCa channel was significantly inhibited by NaHS (6 × 10⁻5 and 12 × 10⁻5 mol/L) in a dose-dependent manner. And IBKCa at 60 mV decreased from (16.68 ± 1.23) to (15.26 ± 2.67) and (13.80 ± 3.04) pA/pF respectively(both P<0.05). CONCLUSIONS: H2S at low concentrations increases the spontaneous contraction of rat colonic smooth muscle in a dose-dependent manner. Such an effect may be due to a direct activation of L-type calcium channel and an inhibition of BKCa channel in smooth muscle cells.

Efficacy of Polyethylene Glycol Electrolyte Powder Combined With Linaclotide for Colon Cleansing in Patients With Chronic Constipation Undergoing Colonoscopy: A Multicenter, Single-Blinded, Randomized Controlled Trial.

INTRODUCTION: Constipation is an independent risk factor for poor bowel preparation. This study aimed to evaluate the bowel cleansing efficacy and safety of polyethylene glycol (PEG) combined with linaclotide (lin) for colonoscopy in patients with chronic constipation (CC). METHODS: This single-blinded, randomized, controlled, and multicenter study was conducted from July 2021 to December 2022 at 7 hospitals. Patients with CC who underwent colonoscopies were enrolled and randomly assigned to 4 groups with split-PEG regimens: 4L-PEG group, 4L-PEG+1d-Lin group, 3L-PEG+1d-Lin group, and 3L-PEG+3d-Lin group. The primary outcome was rates of adequate bowel preparation, defined as a total BBPS score ≥6 and a score ≥2 for each segment. Secondary outcomes were adverse effects, sleep quality, willingness to repeat the colonoscopy, adenoma detection rate, and polyp detection rate. RESULTS: Five hundred two patients were enrolled. The rates of adequate bowel preparation (80.0% vs 60.3%, P < 0.001; 84.4% vs 60.3%, P < 0.001) and the total Boston Bowel Preparation Scale (BBPS) scores (6.90 ± 1.28 vs 6.00 ± 1.61, P < 0.001; 7.03 ± 1.24 vs 6.00 ± 1.61, P < 0.01) in the 4L-PEG+1d-Lin group and the 3L-PEG+3d-Lin group were superior to that in the 4L-PEG group. Compared with the 4L-PEG group, the 4L-PEG+1d-Lin group (66.7% vs 81.7%, P = 0.008) and the 3L-PEG+3d-Lin group (75.0% vs 81.7%, P = 0.224) had a lower percentage of mild adverse events. No statistically significant difference in willingness to repeat the colonoscopy, sleep quality, polyp detection rate, or adenoma detection rate was observed among groups. DISCUSSION: PEG combined with linaclotide might be an effective method for bowel preparation before colonoscopy in patients with CC.

A model for identification of potential phase-separated proteins based on protein sequence, structure and cellular distribution.

The cells are like a highly industrialized and urbanized city, filled with numerous biological macromolecules and metabolites, forming a crowded environment. While, the cells have compartmentalized organelles to complete different biological processes efficiently and orderly. However, membraneless organelles are more dynamic and adaptable for transient events including signal transduction and molecular interactions. Liquid-liquid phase separation (LLPS) is a mechanism that is widespread in which macromolecules form condensates without membranes to exert biological functions in crowded environments. Due to the lack of deep understanding of phase-separated proteins, platforms exploring phase-separated proteins by high-throughput methods is lacking. Bioinformatics has its unique properties and has proven to be a great impetus in multiple fields. Here, We integrated the amino acid sequence, protein structure, and cellular localization, then developed a workflow for screening phase-separated proteins and identified a novel cell cycle-related phase separation protein, serine/arginine-rich splicing factor 2 (SRSF2). In conclusion, we developed a workflow as a useful resource for predicting phase-separated proteins based on multi-prediction tool, which has an important contribution to the further identification of phase-separated proteins and the development strategies for treating disease.

Downregulation of BDNF-TrkB signaling may contribute to the colonic motility disorders in mice with streptozocin-induced diabetes.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) acts as a neuromodulator to regulate gut motility, but the role of BDNF in diabetes-related dysmotility is uncertain. The aim of this study was to investigate the possible involvement of BDNF and its receptor TrkB in the colonic hypomotility of mice with streptozotocin (STZ)-induced diabetes. METHODS: A single intraperitoneal injection of STZ was used to establish a type 1 diabetes model. An organ bath system was applied to observe the contractile activities of colonic muscle strips. Immunofluorescence and western blotting were performed to evaluate the expression of BDNF and TrkB in the colon. ELISA was used to detect BDNF and SP levels in the serum and colon. The patch-clamp technique was applied to record the currents of L-type calcium channels and large conductance Ca2+ -activated K+ channels on smooth muscle cells. KEY RESULTS: Compared with healthy controls, diabetic mice showed attenuated colonic muscle contraction (p < 0.001), which was partly reversed by BDNF supplementation. TrkB protein expression was significantly reduced in diabetic mice (p < 0.05). In addition, both BDNF and substance P (SP) levels were decreased, and exogenous administration of BDNF increased SP levels in diabetic mice (p < 0.05). Both the TrkB antagonist and the TrkB antibody inhibited the spontaneous contraction of colonic muscle strips (p < 0.01). Moreover, the BDNF-TrkB signaling system enhanced SP-induced muscle contraction. CONCLUSIONS: Downregulation of BDNF/TrkB signaling and reduced SP release from the colon may contribute to the colonic hypomotility associated with type 1 diabetes. Brain-derived neurotrophic factor supplementation may have therapeutic potential for diabetes-related constipation.

Losartan attenuates acetic acid enema-induced visceral hypersensitivity by inhibiting the ACE1/Ang II/AT1 receptor axis in enteric glial cells.

Enteric glial cells (EGCs) play an important role in visceral hypersensitivity associated with irritable bowel syndrome (IBS). Losartan (Los) is known to reduce pain; however, its function in IBS is unclear. The present study aimed to investigate Los's therapeutic effect on visceral hypersensitivity in IBS rats. Thirty rats were randomly divided into control, acetic acid enema (AA), AA + Los low, medium and high dose groups in vivo. EGCs were treated with lipopolysaccharide (LPS) and Los in vitro. The molecular mechanisms were explored by assessing the expression of EGC activation markers, pain mediators, inflammatory factors and angiotensin-converting enzyme 1(ACE1)/angiotensin II (Ang II)/Ang II type 1 (AT1) receptor axis molecules in colon tissue and EGCs. The results showed that the rats in the AA group showed significantly higher visceral hypersensitivity than the control rats, which was alleviated by different doses of Los. The expression of GFAP, S100ß, substance P (SP), calcitonin gene-related peptide (CGRP), transient receptor potential vanilloid 1 (TRPV1), tumor necrosis factor (TNF), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) was considerably increased in colonic tissues of AA group rats and LPS-treated EGCs compared with control rats and EGCs, and reduced by Los. In addition, Los reversed ACE1/Ang II/AT1 receptor axis upregulation in AA colon tissues and LPS-treated EGCs. These results show that Los inhibits ACE1/Ang II/AT1 receptor axis upregulation by suppressing EGC activation, resulting in reduced expression of pain mediators and inflammatory factors, thereby alleviating visceral hypersensitivity.

Small intestinal bacterial overgrowth and orocecal transit time in patients of nonalcoholic fatty liver disease.

OBJECTIVE: The aim of the present study is to explore the frequency of small intestinal bacterial overgrowth (SIBO) and orocecal transit time (OCTT) in patients with nonalcoholic fatty liver disease (NAFLD). PATIENTS AND METHODS: 103 patients with NAFLD and 49 healthy controls were enrolled. Clinical indicators such as BMI, liver function, blood lipids, homeostasis model assessment-insulin resistance (HOMA-IR), serum endotoxin of NAFLD patients were collected and examined. FibroTouch was used to detect the controlled attenuation parameter (CAP) and liver stiffness measurement (LSM). SIBO and OCTT were measured by the lactulose hydrogen breath test. RESULTS: The incidence of SIBO in NAFLD patients (58.3%) was significantly higher than that in healthy controls (26.5%). The level of serum endotoxin in NAFLD patients was higher than that in healthy controls. The levels of CAP, LSM, serum endotoxin, alanine transaminase, asperate aminotransferase and HOMA-IR in SBIO-positive NAFLD patients were higher than those in SIBO-negative patients. There was no significant difference in glutamyl transpeptidase triglyceride, low density lipoprotein and BMI between the two groups. OCTT in NAFLD patients was longer than that in healthy controls. It was also observed that OCTT in SIBO-positive NAFLD patients was significantly delayed compared with SIBO-negative NAFLD patients. CONCLUSIONS: Patients with NAFLD exhibit the increased incidence rate of SIBO and prolonged OCTT; SIBO in NAFLD patients maybe a contributing factor to the elevated transaminase, hepatic steatosis, progression of liver fibrosis and prolonged OCTT.