Identification and Expression Analysis of SLAC/SLAH Gene Family in Brassica napus L.

Slow type anion channels (SLAC/SLAHs) play important roles during anion transport, growth and development, abiotic stress responses and hormone responses in plants. However, there is few report on SLAC/SLAHs in rapeseed (Brassica napus). Genome-wide identification and expression analysis of SLAC/SLAH gene family members were performed in B. napus. A total of 23 SLAC/SLAH genes were identified in B. napus. Based on the structural characteristics and phylogenetic analysis of these members, the SLAC/SLAHs could be classified into three main groups. Transcriptome data demonstrated that BnSLAH3 genes were detected in various tissues of the rapeseed and could be up-regulated by low nitrate treatment in roots. BnSLAC/SLAHs were exclusively localized on the plasma membrane in transient expression of tobacco leaves. These results will increase our understanding of the evolution and expression of the SLAC/SLAHs and provide evidence for further research of biological functions of candidates in B. napus.

The prognostic value of Piezo1 in breast cancer patients with various clinicopathological features.

The effects of piezo-type mechanosensitive ion channel component 1 (Piezo1) in sensing extracellular mechanical stress have been well investigated. Recently, Piezo1's vital role in cancerogenesis has been demonstrated by many studies. Nonetheless, the prognostic value of Piezo1 in cancer still remains unexplored and unclear. This article aims to investigate the prognostic value of Piezo1 in breast cancer. Human Protein Atlas and the Cancer Genome Atlas (TCGA) databases were used to examine Piezo1 expression in different human tissues and human cell lines. The discrepancies of Piezo1 mRNA expression in breast cancer patients with different clinicopathological features were assessed using bc-GenExMiner. The prognostic value of Piezo1 in breast cancer patients was evaluated using Kaplan-Meier plotter. Piezo1 mRNA was extensively expressed in human tissues and cell lines, particularly in breast and cancerous breast cancer cell line MCF7. High Piezo1 expression was found correlated with poor prognosis of breast cancer. Survival analysis further confirmed unfavorable prognosis of high Piezo1 expression in breast cancer patients with lymph node positive, estrogen receptor positive, Grade 2 (Scarff-Bloom-Richardson grading system), luminal A, and human epidermal growth factor receptor 2 overexpression, respectively. This study suggested that Piezo1 can serve as a prognostic indicator of breast cancer.

Effect of Piezo1 Overexpression on Peritumoral Brain Edema in Glioblastomas.

BACKGROUND AND PURPOSE: Previous studies have suggested that increased mortality and disability in patients with brain tumor are associated with peritumoral brain edema. However, the mechanism of peritumoral brain edema in brain tumors is unknown. This study aimed to investigate the effect of Piezo1 overexpression on peritumoral brain edema in glioblastomas. MATERIALS AND METHODS: The Piezo1 expression in cell lines and paired samples was detected by quantitative reverse transcription polymerase chain reaction, Western blot, and immunohistochemistry. Sixty-four patients with glioblastomas were analyzed retrospectively. The Piezo1 expression of tumor tissue was detected by immunohistochemistry. The diameters of tumor and edema were measured by preoperative MR imaging, and the edema index value was calculated. RESULTS: Western blot and quantitative reverse transcription polymerase chain reaction showed that Piezo1 expression was higher in 6 glioma cell lines than in the normal astrocyte cell line. Compared with peritumoral tissues, Piezo1 was up-regulated in tumor tissues. Sixty-four patients with glioblastomas were enrolled in further study. Piezo1 was higher in the moderate edema group than in the mild edema group (P < .001), higher in the severe edema group than in the moderate edema group (P < .001), and correlated with the edema index (r = 0.73; P < .001). Receiver operating characteristic curve analysis showed that the edema index yielded an area under the curve of 0.867 (95% CI, 0.76-0.97; P < .001), with a sensitivity of 100% and a specificity of 70%. CONCLUSIONS: Piezo1 overexpression is positively correlated with the degree of peritumoral brain edema in glioblastomas. Predicting high Piezo1 expression in tumor tissues based on the edema extent shows good sensitivity and specificity.

The voltage-gated proton channel hHv1 is functionally expressed in human chorion-derived mesenchymal stem cells.

The voltage-gated proton channel Hv1 is widely expressed, among others, in immune and cancer cells, it provides an efficient cytosolic H+extrusion mechanism and regulates vital functions such as oxidative burst, migration and proliferation. Here we demonstrate the presence of human Hv1 (hHv1) in the placenta/chorion-derived mesenchymal stem cells (cMSCs) using RT-PCR. The voltage- and pH-dependent gating of the current is similar to that of hHv1 expressed in cell lines and that the current is blocked by 5-chloro-2-guanidinobenzimidazole (ClGBI) and activated by arachidonic acid (AA). Inhibition of hHv1 by ClGBI significantly decreases mineral matrix production of cMSCs induced by conditions mimicking physiological or pathological (inorganic phosphate, Pi) induction of osteogenesis. Wound healing assay and single cell motility analysis show that ClGBI significantly inhibits the migration of cMSCs. Thus, seminal functions of cMSCs are modulated by hHv1 which makes this channel as an attractive target for controlling advantages/disadvantages of MSCs therapy.

The function of Piezo1 in colon cancer metastasis and its potential regulatory mechanism.

OBJECTIVE: Increasing evidence has revealed that mechanical stress and elevated mechanical signals promote malignant tumor transformation and metastasis. This study aimed to explore the function of the mechanically activated ion-channel Piezo1 in the colon cancer metastasis and its potential regulatory mechanism. METHODS: First, we examined the expression levels of Piezo1 and mitochondrial calcium uniporter (MCU) both in colon cancer tissues and assessed the prognostic value of Piezo1 and MCU in a colon cancer cohort (n = 110). Second, functional assays were performed to investigate the effects of Piezo1 and MCU on colon cancer cell migration, invasion, and mitochondrial membrane potential. Third, we analyzed the expression of Piezo1, MCU, and HIF-1α by overexpressing/silencing each other's expression. RESULTS: We found that Piezo1 was up-regulated and MCU was down-regulated in colon cancer tissues. Piezo1 and MCU were both correlated with poor prognosis of patients with colon cancer. Overexpressing Piezo1 and silencing MCU could promote colon cancer cell migration and metastasis, reduce mitochondrial membrane potential, and promote each other's expression. We also found that HIF-1α was up-regulated in colon cancer tissues. Additionally, silencing Piezo1 inhibited the expression of HIF-1α and VEGF, which was contrary to MCU silencing. Intriguingly, Piezo1-overexpressing cells did not regain their migration behaviors when HIF-1α expression was inhibited, which was accompanied with the re-expression of MCU and VEGF. CONCLUSION: In our study, Piezo1 is involved in colon cancer cell metastasis. Furthermore, our findings indicated a possible Piezo1-MCU-HIF-1α-VEGF axis, which still need further exploration.

Progesterone and estrogen regulate NALCN expression in human myometrial smooth muscle cells.

During pregnancy, the uterus transitions from a quiescent state to an excitable, highly contractile state to deliver the fetus. Two important contributors essential for this transition are hormones and ion channels, both of which modulate myometrial smooth muscle cell (MSMC) excitability. Recently, the sodium (Na+) leak channel, nonselective (NALCN), was shown to contribute to a Na+ leak current in human MSMCs, and mice lacking NALCN in the uterus had dysfunctional labor. Microarray data suggested that the proquiescent hormone progesterone (P4) and the procontractile hormone estrogen (E2) regulated this channel. Here, we sought to determine whether P4 and E2 directly regulate NALCN. In human MSMCs, we found that NALCN mRNA expression decreased by 2.3-fold in the presence of E2 and increased by 5.6-fold in the presence of P4. Similarly, E2 treatment decreased, and P4 treatment restored NALCN protein expression. Additionally, E2 significantly inhibited, and P4 significantly enhanced an NALCN-dependent leak current in MSMCs. Finally, we identified estrogen response and progesterone response elements (EREs and PREs) in the NALCN promoter. With the use of luciferase assays, we showed that the PREs, but not the ERE, contributed to regulation of NALCN expression. Our findings reveal a new mechanism by which NALCN is regulated in the myometrium and suggest a novel role for NALCN in pregnancy.

Piezo1 regulates calcium oscillations and cytokine release from astrocytes.

Astrocytes are important for information processing in the brain and they achieve this by fine-tuning neuronal communication via continuous uptake and release of biochemical modulators of neurotransmission and synaptic plasticity. Often overlooked are their important functions in mechanosensation. Indeed, astrocytes can detect pathophysiological changes in the mechanical properties of injured, ageing, or degenerating brain tissue. We have recently shown that astrocytes surrounding mechanically-stiff amyloid plaques upregulate the mechanosensitive ion channel, Piezo1. Moreover, ageing transgenic Alzheimer's rats harboring a chronic peripheral bacterial infection displayed enhanced Piezo1 expression in amyloid plaque-reactive astrocytes of the hippocampus and cerebral cortex. Here, we have shown that the bacterial endotoxin, lipopolysaccharide (LPS), also upregulates Piezo1 in primary mouse cortical astrocyte cultures in vitro. Activation of Piezo1, via the small molecule agonist Yoda1, enhanced Ca2+ influx in both control and LPS-stimulated astrocytes. Moreover, Yoda1 augmented intracellular Ca2+ oscillations but decreased subsequent Ca2+ influx in response to adenosine triphosphate (ATP) stimulation. Neither blocking nor activating Piezo1 affected cell viability. However, LPS-stimulated astrocyte cultures exposed to the Piezo1 activator, Yoda1, migrated significantly slower than reactive astrocytes treated with the mechanosensitive channel-blocking peptide, GsMTx4. Furthermore, our data show that activating Piezo1 channels inhibits the release of cytokines and chemokines, such as IL-1ß, TNFα, and fractalkine (CX3 CL1), from LPS-stimulated astrocyte cultures. Taken together, our results suggest that astrocytic Piezo1 upregulation may act to dampen neuroinflammation and could be a useful drug target for neuroinflammatory disorders of the brain.

Aging alters Hv1-mediated microglial polarization and enhances neuroinflammation after peripheral surgery.

Perioperative neurocognitive disorders have been widely recognized as common adverse events after surgical intervention. Aging is one of the most important independent risk factors for worsened cognitive outcome, and this deterioration is linked to exacerbated microglia-mediated neuroinflammation in the aged brain. Under pathological stimulation, microglia are capable of polarizing toward proinflammatory M1 and anti-inflammatory M2 phenotypes. In the present study, we examined how aging affects microglial responses and neuroinflammation following peripheral surgery. Adult (2-3 months) and aged (18 months old) male C57/BL6 mice were subjected to tibial fracture or sham surgery. Aged mice exhibited higher level of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) in the hippocampus. The expression of synaptic protein synaptophysin (SYP) was also markedly reduced in the aged brain after the surgery. Both adult and aged mice showed significant increases in M1 microglial polarization (CD16/32). In contrast, tibial fracture surgery induced a decreased M2 microglial polarization (CD206, Ym1/2, Arg1) in aged brain but enhanced M2 microglial polarization in adult brain. Aged mice have upregulated voltage-gated proton channel (Hv1) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit expression compared with adult mice. The percentage of CD16/32-positive M1 microglia colabeling with Hv1 was higher in aged mice after tibial fracture surgery. Thus, Hv1/NADPH oxidase upregulation in the aged brain may shift the dynamic equilibrium of microglial activation toward M1 polarization and exaggerate postoperative neuroinflammatory responses after peripheral surgical intervention.

Changes in excitability and ion channel expression in neurons of the major pelvic ganglion in female type II diabetic mice.

Bladder cystopathy and autonomic dysfunction are common complications of diabetes, and have been associated with changes in ganglionic transmission and some measures of neuronal excitability in male mice. To determine whether type II diabetes also impacts excitability of ganglionic neurons in females, we investigated neuronal excitability and firing properties, as well as underlying ion channel expression, in major pelvic ganglion (MPG) neurons in control, 10-week, and 21-week Leprdb/db mice. Type II diabetes in Leprdb/db animals caused a non-linear change in excitability and firing properties of MPG neurons. At 10 weeks, cells exhibited increased excitability as demonstrated by an increased likelihood of firing multiple spikes upon depolarization, decreased rebound spike latency, and overall narrower action potential half-widths as a result of increased depolarization and repolarization slopes. Conversely, at 21 weeks MPG neurons of Leprdb/db mice reversed these changes, with spiking patterns and action-potential properties largely returning to control levels. These changes are associated with numerous time-specific changes in calcium, sodium, and potassium channel subunit mRNA levels. However, Principal Components Analysis of channel expression patterns revealed that rectification of excitability is not simply a return to control levels, but rather a distinct ion channel expression profile in 21-week Leprdb/db neurons. These data indicate that type II diabetes can impact the excitability of post-ganglionic, autonomic neurons of female mice, and suggest that the non-linear progression of these properties with diabetes may be the result of compensatory changes in channel expression that act to rectify disrupted firing patterns of Leprdb/db MPG neurons.

Potential Role of H-Ferritin in Mitigating Valvular Mineralization.

Objective- Calcific aortic valve disease is a prominent finding in elderly and in patients with chronic kidney disease. We investigated the potential role of iron metabolism in the pathogenesis of calcific aortic valve disease. Approach and Results- Cultured valvular interstitial cells of stenotic aortic valve with calcification from patients undergoing valve replacement exhibited significant susceptibility to mineralization/osteoblastic transdifferentiation in response to phosphate. This process was abrogated by iron via induction of H-ferritin as reflected by lowering ALP and osteocalcin secretion and preventing extracellular calcium deposition. Cellular phosphate uptake and accumulation of lysosomal phosphate were decreased. Accordingly, expression of phosphate transporters Pit1 and Pit2 were repressed. Translocation of ferritin into lysosomes occurred with high phosphate-binding capacity. Importantly, ferritin reduced nuclear accumulation of RUNX2 (Runt-related transcription factor 2), and as a reciprocal effect, it enhanced nuclear localization of transcription factor Sox9 (SRY [sex-determining region Y]-box 9). Pyrophosphate generation was also increased via upregulation of ENPP2 (ectonucleotide pyrophosphatase/phosphodiesterase-2). 3H-1, 2-dithiole-3-thione mimicked these beneficial effects in valvular interstitial cell via induction of H-ferritin. Ferroxidase activity of H-ferritin was essential for this function, as ceruloplasmin exhibited similar inhibitory functions. Histological analysis of stenotic aortic valve revealed high expression of H-ferritin without iron accumulation and its relative dominance over ALP in noncalcified regions. Increased expression of H-ferritin accompanied by elevation of TNF-α (tumor necrosis factor-α) and IL-1ß (interleukin-1ß) levels, inducers of H-ferritin, corroborates the essential role of ferritin/ferroxidase via attenuating inflammation in calcific aortic valve disease. Conclusions- Our results indicate that H-ferritin is a stratagem in mitigating valvular mineralization/osteoblastic differentiation. Utilization of 3H-1, 2-dithiole-3-thione to induce ferritin expression may prove a novel therapeutic potential in valvular mineralization.

Mechanical exposure and diacerein treatment modulates integrin-FAK-MAPKs mechanotransduction in human osteoarthritis chondrocytes.

BACKGROUND: Progression of osteoarthritis (OA) is characterized by an excessive production of matrix degrading enzymes and insufficient matrix repair. Despite of active research in this area, it is still unclear how the combination of mechanical exposure and drug therapy works. This study was done to explore the impact of the disease modifying OA drug (DMOAD) diacerein and moderate tensile strain on the anabolic metabolism and the integrin-FAK-MAPKs signal transduction cascade of OA and non-OA chondrocytes. METHODS: Cyclic tensile strain was applied in terms of three different intensities by the Flexcell tension system. Influence on catabolic parameters such as MMPs, ADAMTS, and IL-6 were assessed by qPCR. Changes in phosphorylation of FAK, STAT3 as well as MAP kinases were verified by western blot analysis. Intracellular calcium was measured fluorimetrically using fura-2. RESULTS: Tensile strain at moderate intensity (SM/SA profile) proved to be most efficient in terms of reducing production of matrix degrading enzyme and IL-6 expression. Treatment with diacerein by itself and diacerein in combination with SM/SA stimulation reduced phosphorylation of FAK and STAT3, which is more pronounced in OA cells. Pretreatment with diacerein for 7 days resulted in an increase in the sensitivity to Yoda1, the agonist for the mechanically activated ion channel Piezo1. However, in OA chondrocytes a significant reduction in Piezo1 expression was observed following treatment with diacerein. CONCLUSION: Our results demonstrated for the first time that diacerein intensively intervenes in the regulation of FAK and STAT3 and influences components considered relevant for the progression of OA, even in the presence of mechanical stimulation.

A Feedforward Mechanism Mediated by Mechanosensitive Ion Channel PIEZO1 and Tissue Mechanics Promotes Glioma Aggression.

Alteration of tissue mechanical properties is a physical hallmark of solid tumors including gliomas. How tumor cells sense and regulate tissue mechanics is largely unknown. Here, we show that mechanosensitive ion channel Piezo regulates mitosis and tissue stiffness of Drosophila gliomas, but not non-transformed brains. PIEZO1 is overexpressed in aggressive human gliomas and its expression inversely correlates with patient survival. Deleting PIEZO1 suppresses the growth of glioblastoma stem cells, inhibits tumor development, and prolongs mouse survival. Focal mechanical force activates prominent PIEZO1-dependent currents from glioma cell processes, but not soma. PIEZO1 localizes at focal adhesions to activate integrin-FAK signaling, regulate extracellular matrix, and reinforce tissue stiffening. In turn, a stiffer mechanical microenvironment elevates PIEZO1 expression to promote glioma aggression. Therefore, glioma cells are mechanosensory in a PIEZO1-dependent manner, and targeting PIEZO1 represents a strategy to break the reciprocal, disease-aggravating feedforward circuit between tumor cell mechanotransduction and the aberrant tissue mechanics. VIDEO ABSTRACT.

The increased expression of Piezo1 and Piezo2 ion channels in human and mouse bladder carcinoma.

BACKGROUND: Piezo1/2, a mechanically activated ion channel, is believed to play an important role in bladder carcinogenesis process. Piezo1/2 expression has not been previously reported in urinary bladder carcinoma, and little is known about its significance in bladder carcinogenesis. OBJECTIVES: In our study, we aimed to evaluate the Piezo1 and Piezo2 expression as developmental in mouse bladder tissue and bladder cancer tissue of mice and humans. MATERIAL AND METHODS: The detection of developmental expression was performed on P0-P90 days in bladder tissue of Balb/c strain mice. Mice were divided into bladder cancer (n = 40) and control groups (n = 10). Bladder cancer in mice was created by using N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). In the study, 60 human subjects were included, whose normal tissues were used as controls. After the histopathological evaluation, the expression of Piezo1/2 genes was examined by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry in tumor and normal tissues. RESULTS: In developmental period of the mice, Piezo1 expression increased on days 21 and 90, whereas Piezo2 expression increased on day 7 and decreased on day 90 in mouse bladder tissues. There was a significant increase in the expression of Piezo1/2 in both cancer groups compared to the control group. Piezo1 expression was significantly increased at tumor size, stage and grade. Piezo2 expression was upregulated in high grade tumors in human subjects. CONCLUSIONS: The developmental changes of Piezo expression on specific days demonstrate the role of these channels in bladder cancer development. The dysfunction of Piezo1/2 expression may contribute to the carcinogenesis of bladder cancer by causing proliferative changes and angiogenesis. The expression of Piezo1/2 can provide new prognostic information for disease progression.

Dapagliflozin, a Sodium-Glucose Co-Transporter 2 Inhibitor, Acutely Reduces Energy Expenditure in BAT via Neural Signals in Mice.

Selective sodium glucose cotransporter-2 inhibitor (SGLT2i) treatment promotes urinary glucose excretion, thereby reducing blood glucose as well as body weight. However, only limited body weight reductions are achieved with SGLT2i treatment. Hyperphagia is reportedly one of the causes of this limited weight loss. However, the effects of SGLT2i treatment on systemic energy expenditure have not been fully elucidated. Herein, we investigated the acute effects of dapagliflozin, a SGLT2i, on systemic energy expenditure in mice. Eighteen hours after dapagliflozin treatment oxygen consumption and brown adipose tissue (BAT) expression of ucp1, a thermogenesis-related gene, were significantly decreased as compared to those after vehicle treatment. In addition, dapagliflozin significantly suppressed norepinephrine (NE) turnover in BAT and c-fos expression in the rostral raphe pallidus nucleus (rRPa) which contains the sympathetic premotor neurons responsible for thermogenesis. These findings indicate that the dapagliflozin-mediated acute decrease in energy expenditure involves a reduction in BAT thermogenesis via decreased sympathetic nerve activity from the rRPa. Furthermore, common hepatic branch vagotomy abolished the reductions in ucp1 expression and NE contents in BAT and c-fos expression in the rRPa. In addition, alterations in hepatic carbohydrate metabolism, such as decreases in glycogen contents and upregulation of phosphoenolpyruvate carboxykinase, manifested prior to the suppression of BAT thermogenesis, e.g. 6 hours after dapagliflozin treatment. Collectively, these results suggest that SGLT2i treatment acutely suppresses energy expenditure in BAT via regulation of an inter-organ neural network consisting of the common hepatic vagal branch and sympathetic nerves.

The Molecular Signature of HIV-1-Associated Lipomatosis Reveals Differential Involvement of Brown and Beige/Brite Adipocyte Cell Lineages.

Highly active antiretroviral therapy has remarkably improved quality of life of HIV-1-infected patients. However, this treatment has been associated with the so-called lipodystrophic syndrome, which conveys a number of adverse metabolic effects and morphological alterations. Among them, lipoatrophy of subcutaneous fat in certain anatomical areas and hypertrophy of visceral depots are the most common. Less frequently, lipomatous enlargements of subcutaneous fat at distinct anatomic areas occur. Lipomatous adipose tissue in the dorso-cervical area ("buffalo hump") has been associated with a partial white-to-brown phenotype transition and with increased cell proliferation, but, to date, lipomatous enlargements arising in other parts of the body have not been characterized. In order to establish the main molecular events associated with the appearance of lipomatosis in HIV-1 patients, we analyzed biopsies of lipomatous tissue from "buffalo hump" and from other anatomical areas in patients, in comparison with healthy subcutaneous adipose tissue, using a marker gene expression approach. Both buffalo-hump and non-buffalo-hump lipomatous adipose tissues exhibited similar patterns of non-compromised adipogenesis, unaltered inflammation, non-fibrotic phenotype and proliferative activity. Shorter telomere length, prelamin A accumulation and SA-ß-Gal induction, reminiscent of adipocyte senescence, were also common to both types of lipomatous tissues. Buffalo hump biopsies showed expression of marker genes of brown adipose tissue (e.g. UCP1) and, specifically, of "classical" brown adipocytes (e.g. ZIC1) but not of beige/brite adipocytes. No such brown fat-related gene expression occurred in lipomatous tissues at other anatomical sites. In conclusion, buffalo hump and other subcutaneous adipose tissue enlargements from HIV-1-infected patients share a similar lipomatous character. However, a distorted induction of white-to-"classical brown adipocyte" phenotype appears unique of dorso-cervical lipomatosis. Thus, the insults caused by HIV-1 viral infection and/or antiretroviral therapy leading to lipomatosis are acting in a location- and adipocyte lineage-dependent manner.

Genipin suppresses NLRP3 inflammasome activation through uncoupling protein-2.

Incomplete clearance of apoptotic cells and reactive oxygen species (ROS) release are known to trigger inflammasome activation causing severe inflammation in acute lung injury and various metabolic and autoimmune diseases. Moreover, it has been reported that apoptotic cell clearance and ROS-mediated apoptosis critically depend on mitochondrial uncoupling protein-2 (UCP2). However, the relationship between UCP2 and inflammasome activation has not been studied. This report investigates the role of UCP2 in the expression and activation of NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome in human macrophages. We found that UCP2 overexpression significantly enhanced the expression levels of NLRP3. The NLRP3 expression levels were significantly suppressed in THP1 cells treated with genipin, a UCP2 inhibitor, compared to controls. In addition, genipin altered adenosine triphosphate (ATP)- and hydrogen peroxide (H2O2)-mediated interleukin-1 beta (IL-1ß) secretion and significantly suppressed caspase-1 activity in inflammasome-activated human macrophages. Taken together, our results suggest that genipin modulates NLRP3 inflammasome activation and ATP- or H2O2-mediated IL-1ß release.

Polymorphisms of the UCP2 Gene Are Associated with Glomerular Filtration Rate in Type 2 Diabetic Patients and with Decreased UCP2 Gene Expression in Human Kidney.

INTRODUCTION: Uncoupling protein 2 (UCP2) reduces production of reactive oxygen species (ROS) by mitochondria. ROS overproduction is one of the major contributors to the pathogenesis of chronic diabetic complications, such as diabetic kidney disease (DKD). Thus, deleterious polymorphisms in the UCP2 gene are candidate risk factors for DKD. In this study, we investigated whether UCP2 -866G/A, Ala55Val and Ins/Del polymorphisms were associated with DKD in patients with type 2 diabetes mellitus (T2DM), and whether they had an effect on UCP2 gene expression in human kidney tissue biopsies. MATERIALS AND METHODS: In a case-control study, frequencies of the UCP2 -866G/A, Ala55Val and Ins/Del polymorphisms as well as frequencies of the haplotypes constituted by them were analyzed in 287 T2DM patients with DKD and 281 T2DM patients without this complication. In a cross-sectional study, UCP2 gene expression was evaluated in 42 kidney biopsy samples stratified according to the presence of the UCP2 mutated -866A/55Val/Ins haplotype. RESULTS: In the T2DM group, multivariate logistic regression analysis showed that the -866A/55Val/Ins haplotype was an independent risk factor for DKD (OR = 2.136, 95% CI 1.036-4.404), although neither genotype nor allele frequencies of the individual polymorphisms differed between case and control groups. Interestingly, T2DM patients carrying the mutated haplotype showed decreased estimated glomerular filtration rate (eGFR) when compared to subjects with the reference haplotype (adjusted P= 0.035). In kidney biopsy samples, UCP2 expression was significantly decreased in UCP2 mutated haplotype carriers when compared to kidneys from patients with the reference haplotype (0.32 ± 1.20 vs. 1.85 ± 1.16 n fold change; adjusted P< 0.000001). DISCUSSION: Data reported here suggest that the UCP2 -866A/55Val/Ins haplotype is associated with an increased risk for DKD and with a lower eGFR in T2DM patients. Furthermore, this mutated haplotype was associated with decreased UCP2 gene expression in human kidneys.

Transcriptome response signatures associated with the overexpression of a mitochondrial uncoupling protein (AtUCP1) in tobacco.

Mitochondrial inner membrane uncoupling proteins (UCP) dissipate the proton electrochemical gradient established by the respiratory chain, thus affecting the yield of ATP synthesis. UCP overexpression in plants has been correlated with oxidative stress tolerance, improved photosynthetic efficiency and increased mitochondrial biogenesis. This study reports the main transcriptomic responses associated with the overexpression of an UCP (AtUCP1) in tobacco seedlings. Compared to wild-type (WT), AtUCP1 transgenic seedlings showed unaltered ATP levels and higher accumulation of serine. By using RNA-sequencing, a total of 816 differentially expressed genes between the investigated overexpressor lines and the untransformed WT control were identified. Among them, 239 were up-regulated and 577 were down-regulated. As a general response to AtUCP1 overexpression, noticeable changes in the expression of genes involved in energy metabolism and redox homeostasis were detected. A substantial set of differentially expressed genes code for products targeted to the chloroplast and mainly involved in photosynthesis. The overall results demonstrate that the alterations in mitochondrial function provoked by AtUCP1 overexpression require important transcriptomic adjustments to maintain cell homeostasis. Moreover, the occurrence of an important cross-talk between chloroplast and mitochondria, which culminates in the transcriptional regulation of several genes involved in different pathways, was evidenced.

Inhibition of Sam68 triggers adipose tissue browning.

Obesity is associated with insulin resistance and type 2 diabetes; molecular mechanisms that promote energy expenditure can be utilized for effective therapy. Src-associated in mitosis of 68 kDa (Sam68) is potentially significant, because knockout (KO) of Sam68 leads to markedly reduced adiposity. In the present study, we sought to determine the mechanism by which Sam68 regulates adiposity and energy homeostasis. We first found that Sam68 KO mice have a significantly reduced body weight as compared to controls, and the difference is explained entirely by decreased adiposity. Interestingly, these effects were not mediated by a difference in food intake; rather, they were associated with enhanced physical activity. When they were fed a high-fat diet, Sam68 KO mice gained much less body weight and fat mass than their WT littermates did, and they displayed an improved glucose and insulin tolerance. In Sam68 KO mice, the brown adipose tissue (BAT), inguinal, and epididymal depots were smaller, and their adipocytes were less hypertrophied as compared to their WT littermates. The BAT of Sam68 KO mice exhibited reduced lipid stores and expressed higher levels of Ucp1 and key thermogenic and fatty acid oxidation genes. Similarly, depots of inguinal and epididymal white adipose tissue (WAT) in Sam68 KO mice appeared browner, their multilocular Ucp1-positive cells were much more abundant, and the expression of Ucp1, Cidea, Prdm16, and Ppargc1a genes was greater as compared to WT controls, which suggests that the loss of Sam68 also promotes WAT browning. Furthermore, in all of the fat depots of the Sam68 KO mice, the expression of M2 macrophage markers was up-regulated, and that of M1 markers was down-regulated. Thus, Sam68 plays a crucial role in controlling thermogenesis and may be targeted to combat obesity and associated disorders.

Placing ion channels into a signaling network of T cells: from maturing thymocytes to healthy T lymphocytes or leukemic T lymphoblasts.

T leukemogenesis is a multistep process, where the genetic errors during T cell maturation cause the healthy progenitor to convert into the leukemic precursor that lost its ability to differentiate but possesses high potential for proliferation, self-renewal, and migration. A new misdirecting "leukemogenic" signaling network appears, composed by three types of participants which are encoded by (1) genes implicated in determined stages of T cell development but deregulated by translocations or mutations, (2) genes which normally do not participate in T cell development but are upregulated, and (3) nondifferentially expressed genes which become highly interconnected with genes expressed differentially. It appears that each of three groups may contain genes coding ion channels. In T cells, ion channels are implicated in regulation of cell cycle progression, differentiation, activation, migration, and cell death. In the present review we are going to reveal a relationship between different genetic defects, which drive the T cell neoplasias, with calcium signaling and ion channels. We suggest that changes in regulation of various ion channels in different types of the T leukemias may provide the intracellular ion microenvironment favorable to maintain self-renewal capacity, arrest differentiation, induce proliferation, and enhance motility.