TRPC6 Research Articles

Canonical Transient Receptor Potential (TRPC) Channels in Cardiovascular Pathology and their Modulators.

Ion channels play a crucial role in various aspects of cardiac function, such as regulating rhythm and contractility. As a result, they serve as key targets for therapeutic interventions in cardiovascular diseases. Cell function is substantially influenced by the concentration of free cytosolic calcium (Ca2+) and the voltage across the plasma membrane. These characteristics are known to be regulated by Ca2+-permeable non-selective cationic channels, although our knowledge of these channels is still inadequate. The transient receptor potential (TRP) superfamily comprises of many non-selective cation channels with diverse Ca2+ permeability. Canonical or classical TRP (TRPC) channels are a subgroup of the TRP superfamily that are expressed ubiquitously in mammalian cells. TRPC channels are multidimensional signalling protein complexes that play essential roles in a variety of physiological and pathological processes in humans, including cancer, neurological disorders, cardiovascular diseases, and others. The objective of this article is to focus on the role that TRPC channels play in the cardiovascular system. The role of TRPC channels will be deeply discussed in cardiovascular pathology. Together, a critical element in developing novel treatments that target TRPC channels is comprehending the molecular mechanisms and regulatory pathways of TRPC channels in related cardiovascular diseases and conditions.

Tinglu Yixin granule inhibited fibroblast-myofibroblast transdifferentiation to ameliorate myocardial fibrosis in diabetic mice

Ethnopharmacological relevanceMyocardial fibrosis is one of the pathological characteristics of advanced diabetic cardiomyopathy (DCM) and serves as the strong evidence of poor prognosis. Among them, the transdifferentiation of cardiac fibroblasts (CFs) may play a crucial role in the development of myocardial fibrosis in DCM. Tinglu Yixin granule (TLYXG) has been clinically used for many years and can significantly improve cardiac function of patients with DCM. However, the effect of TLYXG on myocardial fibrosis in DCM remains unknown, and the underlying mechanisms of its efficacy have yet to be fully understood. Aim of the studyThis study aimed to investigate the impact and underlying mechanism of TLYXG on myocardial fibrosis in diabetes mice. Materials and methodsThe bioactive compounds in TLYXG were identified using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The potential mechanism of TLYXG in treating DCM was predicted using network pharmacology combined with molecular docking and protein-protein docking. The mice model of type 2 diabetes were established by intraperitoneal injection of streptozotocin (STZ) and the high-fat diet (HFD). Indicators of pancreatic islet function, lipids, oxidative stress, and inflammatory factors were tested using kits. Cardiac function was assessed in diabetic mice using echocardiography. Histologic staining was performed to evaluate myocardial hypertrophy and fibrosis. Mechanistically, the hypothesis was tested through rescue experiments. The expression levels of transient receptor potential channel 6 (TRPC6), transforming growth factor-β1 (TGF-β1), collagen I (COL-I) and alpha-smooth muscle actin (α-SMA), along with the mRNA and phosphorylation levels of SMAD family member 3 (Smad3) and protein 38 mitogen-activated protein kinase (p38 MAPK), were assessed using quantitative RT-qPCR, western blot, immunohistochemistry, and immunofluorescence. Neonatal lactating mice were used to extract primary CFs for vitro experiments. Scratch and transwell assays were conducted to assess CFs migration and invasion abilities. Western blot and immunofluorescence were used to evaluate the expression levels of CFs transdifferentiation markers COL-I and α-SMA. ResultsA total of 168 active ingredients were detected in TLYXG based on UPLC-MS and databases. Network pharmacology indicated that TLYXG could improve DCM through inflammatory mediator regulation of TRP channels, TGF-beta signaling pathway, and MAPK signaling pathway. ELISA results showed that TLYXG could ameliorate metabolic levels, inflammation, and oxidative stress in diabetic mice. Echocardiography suggested that TLYXG improved cardiac systolic and diastolic dysfunction in diabetic mice. Histological analysis revealed that TLYXG alleviated myocardial fibrosis in diabetes mice. Additionally, molecular docking analysis indicated strong binding activity between the main active ingredients of TLYXG and TRPC6 of the TRP family. At the molecular level, TLYXG reduced the mRNA and protein expression levels of TRPC6 and TGF-β1 and inhibited the mRNA and phosphorylation levels of Smad3 and p38 MAPK. Furthermore, TLYXG inhibited CFs migration and invasion, and reduced the expression levels of the CFs transdifferentiation markers COL-I and α-SMA. ConclusionTLYXG inhibited the proliferation, migration, invasion and transdifferentiation of CFs by suppressing TGF-β1/Smad3/p38 MAPK signaling through down-regulation of TRPC6, thereby ameliorating myocardial fibrosis in diabetes mice.

TRPC4/5 inhibitors: Phase I results and proof of concept studies.

Transient receptor potential canonical (TRPC) ion channels are expressed in areas of the brain responsible for processing emotion and mood and have been implicated in the pathophysiology of internalizing disorders such as major depressive disorder and anxiety disorders. This review outlines the rationale for targeting TRPC ion channels for drug development, with specific focus on TRPC4 and TRPC5. We provide preclinical evidence that the lack of TRPC4 and TRPC5 channels or its pharmacological inhibition attenuate fear and anxiety without impairing other behaviors in mice. We also report on clinical studies of BI 1358894, a small molecule inhibitor of TRPC4/5 ion channels, demonstrating reduced psychological and physiological responses to induced anxiety/panic-like symptoms in healthy volunteers. Furthermore, we highlight an imaging study that investigated the acute effects of BI 1358894 and showed reduced activation in several brain regions involved in emotional processing. We conclude that these findings demonstrate a critical role for TRPC4 and TRPC5 in emotional processing, even though it remains an open question if the biological signatures of TRPC4/5 inhibition reported here translate into clinical efficacy and indicate that a TRPC4/5 inhibitor might provide a more effective treatment of internalizing disorders.

TRPC3/6 Channels Mediate Mechanical Pain Hypersensitivity via Enhancement of Nociceptor Excitability and of Spinal Synaptic Transmission.

Patients with tissue inflammation or injury often experience aberrant mechanical pain hypersensitivity, one of leading symptoms in clinic. Despite this, the molecular mechanisms underlying mechanical distortion are poorly understood. Canonical transient receptor potential (TRPC) channels confer sensitivity to mechanical stimulation. TRPC3 and TRPC6 proteins, coassembling as heterotetrameric channels, are highly expressed in sensory neurons. However, how these channels mediate mechanical pain hypersensitivity has remained elusive. It is shown that in mice and human, TRPC3 and TRPC6 are upregulated in DRG and spinal dorsal horn under pathological states. Double knockout of TRPC3/6 blunts mechanical pain hypersensitivity, largely by decreasing nociceptor hyperexcitability and spinal synaptic potentiation via presynaptic mechanism. In corroboration with this, nociceptor-specific ablation of TRPC3/6 produces comparable pain relief. Mechanistic analysis reveals that upon peripheral inflammation, TRPC3/6 in primary sensory neurons get recruited via released bradykinin acting on B1/B2 receptors, facilitating BDNF secretion from spinal nociceptor terminals, which in turn potentiates synaptic transmission through TRPC3/6 and eventually results in mechanical pain hypersensitivity. Antagonizing TRPC3/6 in DRG relieves mechanical pain hypersensitivity in mice and nociceptor hyperexcitability in human. Thus, TRPC3/6 in nociceptors is crucially involved in pain plasticity and constitutes a promising therapeutic target against mechanical pain hypersensitivity with minor side effects.

TRPC3 suppression ameliorates synaptic dysfunctions and memory deficits in Alzheimer's disease.

Transient receptor potential canonical (TRPC) channels are widely expressed in the brain; however, their precise roles in neurodegeneration, such as Alzheimer's disease (AD) remain elusive. Bioinformatic analysis of the published single-cell RNA-seq data collected from AD patient cohorts indicates that the Trpc3 gene is uniquely upregulated in excitatory neurons. TRPC3 expression is also upregulated in post-mortem AD brains, and in both acute and chronic mouse models of AD. Functional screening of TRPC3 antagonists resulted in a lead inhibitor JW-65, which completely rescued Aβ-induced neurotoxicity, impaired synaptic plasticity (e.g., LTP), and learning memory in acute and chronic experimental AD models. In cultured rat hippocampal neurons, we found that treatment with soluble β-amyloid oligomers (AβOs) induces rapid and sustained upregulation of the TRPC3 expression selectively in excitatory neurons. This aberrantly upregulated TRPC3 contributes to AβOs-induced Ca 2+ overload through the calcium entry and store-release mechanisms. The neuroprotective action of JW-65 is primarily mediated via restoring AβOs-impaired Ca 2+ /calmodulin-mediated signaling pathways, including calmodulin kinases CaMKII/IV and calcineurin (CaN). The synaptic protective mechanism via TRPC3 inhibition was further supported by hippocampal RNA-seq data from the symptomatic 5xFAD mice after chronic treatment with JW-65. Overall, these findings not only validate TRPC3 as a novel therapeutic target for treating synaptic dysfunction of AD but most importantly, disclose a distinct role of upregulated TRPC3 in AD pathogenesis in mediating Ca 2+ dyshomeostasis.

TRPC6 regulates necroptosis in myocardial ischemia/reperfusion injury via Ca2+/CaMKII signaling pathway

Myocardial ischemia-reperfusion injury (MIRI) frequently complicates postoperative cardiovascular disease treatment. Necroptosis, a cell death mechanism similar to apoptosis, is regulated by specific signaling pathways and plays an important role in MIRI. Receptor-interacting protein 3 (RIP3), a key protein regulating necroptosis during MIRI, directly phosphorylates calmodulin-dependent protein kinase II (CaMKII). Leading to mitochondrial permeablity transition pore (mPTP) opening and inducing necroptosis. Transient receptor potential canonical channel 6 (TRPC6) regulats Ca2+ entry, is linked to CaMKII as an important upstream effector. However, the connection between TRPC6 and MIRI necroptosis remains unclear. The study aimed to investigate the relationship between TRPC6 and MIRI necroptosis, with a specific focus on elucidating the role of TRPC6 in regulating CaMKII phosphorylation during cardiac necroptosis via Ca2+ modulation. Methods and resultsThe experiment used wild-type (WT) and TRPC6 knockout (TRPC6−/−) mice for I/R model construction, and H9c2 myocardial cell line for H/R model. After ischemia-reperfusion (I/R), TRPC6 protein levels in mice significantly increased, exacerbating myocardial injury, infarct size (IS), and cardiac function in WT mice. In contrast, TRPC6 knockout attenuated myocardial injury, IS, and improved cardiac function. The results showed a significant correlation between changes in CaMKII and TRPC6. TRPC6 knockout led to decreased intracellular calcium levels, CaMKII phosphorylation, reactive oxygen species levels, mPTP opening, and improve mitochondrial structure. ConclusionI/R upregulates TRPC6, which mediates Ca2+ entry and CaMKII phosphorylation, exacerbates oxidative stress, and induces necroptosis. These findings suggest a potential therapeutic avenue for mitigating MIRI by targeting TRPC6.

Periphery Pre-S1 and S1 helix nexus for PIP2 at TRPC3 channel

Transient receptor potential canonical 3 (TRPC3) is a calcium-permeable, non-selective cation channel known to be regulated by components of the phospholipase C (PLC)-mediated signaling pathway, such as Ca2+, diacylglycerol (DAG) and phosphatidylinositol 4,5-biphosphate (PI(4,5)P2). However, the molecular gating mechanism by these regulators is not yet fully understood, especially its regulation by PI(4,5)P2, despite the importance of this channel in cardiovascular pathophysiology. Recently, Clarke et al. (2024) have reported that PI(4,5)P2 is a positive modulator for TRPC3 using molecular dynamics simulations and patch-clamp techniques. They have demonstrated a multistep gating mechanism of TRPC3 with the binding of PI(4,5)P2 to the lipid binding site located at the pre-S1/S1 nexus, and the propagation of PI(4,5)P2 sensing to the pore domain via a salt bridge between the TRP helix and the S4–S5 linker.

Normotensive metabolic syndrome in Transient Receptor Potential Canonical Channel type 1 Trpc1-/- mice.

Metabolic syndrome has become a global epidemic, affecting all developed countries and communities with growing economies. Worldwide, increasing efforts have been directed at curbing this growing problem. Mice deleted of the gene encoding Type 1 Transient Receptor Potential Canonical Channel (Trpc1) were found to weigh heavier than controls. They had fasting hyperglycemia and impaired glucose tolerance compared with wild-type controls. Beyond 1 year of age, plasma triglyceride level in Trpc1-/- mice was elevated. Plasma cholesterol levels tended to be higher than in controls. The livers of Trpc1-/- mice were heavier, richer in triglyceride, and more echogenic than those of controls on ultrasound evaluation. Hematocrit was lower in Trpc1-/- mice of both genders beginning at the second to third months of age in the absence of bleeding or hemolysis. Measured by the indirect tail-cuff method or by the direct arterial cannulation, blood pressures in null mice were lower than controls. We conclude that TRPC1 gene regulates body metabolism and that except for hypertension, phenotypes of mice after deletion of the Trpc1 gene resemble mice with metabolic syndrome, suggesting that this could be a good experimental model for future investigation of the pathogenesis and management of this disorder.

Label-free three-dimensional imaging and quantitative analysis of living fibroblasts and myofibroblasts by holotomographic microscopy.

Holotomography (HT) is a cutting-edge fast live-cell quantitative label-free imaging technique. Based on the principle of quantitative phase imaging, it combines holography and tomography to record a three-dimensional map of the refractive index, used as intrinsic optical and quantitative imaging contrast parameter of biological samples, at a sub-micrometer spatial resolution. In this study HT has been employed for the first time to analyze the changes of fibroblasts differentiating towards myofibroblasts - recognized as the main cell player of fibrosis - when cultured in vitro with the pro-fibrotic factor, namely transforming growth factor-β1. In parallel, F-actin, vinculin, α-smooth muscle actin, phospho-myosin light chain 2, type-1 collagen, peroxisome proliferator-activated receptor-gamma coactivator-1α expression and mitochondria were evaluated by confocal laser scanning microscopy. Plasmamembrane passive properties and transient receptor potential canonical channels' currents were also recorded by whole-cell patch-clamp. The fluorescence images and electrophysiological results have been compared to the data obtained by HT and their congruence has been discussed. HT turned out to be a valid approach to morphologically distinguish fibroblasts from well differentiated myofibroblasts while obtaining objective measures concerning volume, surface area, projection area, surface index and dry mass (i.e., the mass of the non-aqueous content inside the cell including proteins and subcellular organelles) of the entire cell, nuclei and nucleoli with the major advantage to monitor outer and inner features in living cells in a non-invasive, rapid and label-free approach. HT might open up new research opportunities in the field of fibrotic diseases. RESEARCH HIGHLIGHTS: Holotomography (HT) is a label-free laser interferometric imaging technology exploiting the intrinsic optical property of cells namely refractive index (RI) to enable a direct imaging and analysis of whole cells or intracellular organelles. HT turned out a valid approach to distinguish morphological features of living unlabeled fibroblasts from differentiated myofibroblasts. HT provided quantitative information concerning volume, surface area, projection area, surface index and dry mass of the entire fibroblasts/myofibroblasts, nuclei and nucleoli.

Selective Assembly of TRPC Channels in the Rat Retina during Photoreceptor Degeneration.

Transient receptor potential canonical (TRPC) channels are calcium channels with diverse expression profiles and physiological implications in the retina. Neurons and glial cells of rat retinas with photoreceptor degeneration caused by retinitis pigmentosa (RP) exhibit basal calcium levels that are above those detected in healthy retinas. Inner retinal cells are the last to degenerate and are responsible for maintaining the activity of the visual cortex, even after complete loss of photoreceptors. We considered the possibility that TRPC1 and TRPC5 channels might be associated with both the high calcium levels and the delay in inner retinal degeneration. TRPC1 is known to mediate protective effects in neurodegenerative processes while TRPC5 promotes cell death. In order to comprehend the implications of these channels in RP, the co-localization and subsequent physical interaction between TRPC1 and TRPC5 in healthy retina (Sprague-Dawley rats) and degenerating (P23H-1, a model of RP) retina were detected by immunofluorescence and proximity ligation assays. There was an overlapping signal in the innermost retina of all animals where TRPC1 and TRPC5 physically interacted. This interaction increased significantly as photoreceptor loss progressed. Both channels function as TRPC1/5 heteromers in the healthy and damaged retina, with a marked function of TRPC1 in response to retinal degenerative mechanisms. Furthermore, our findings support that TRPC5 channels also function in partnership with STIM1 in Müller and retinal ganglion cells. These results suggest that an increase in TRPC1/5 heteromers may contribute to the slowing of the degeneration of the inner retina during the outer retinal degeneration.

New perspectives in prognostication of hepatocellular carcinoma: The role and clinical implications of transient receptor potential family genes.

The study titled "Transient receptor potential-related risk model predicts prognosis of hepatocellular carcinoma patients" is a significant contribution to hepatocellular carcinoma (HCC) research, highlighting the role of transient receptor potential (TRP) family genes in the disease's progression and prognosis. Utilizing data from The Cancer Genome Atlas database, it establishes a new risk assessment model, emphasizing the interaction of TRP genes with tumor proliferation pathways, key metabolic reactions like retinol metabolism, and the tumor immune microenvironment. Notably, the overexpression of the TRPC1 gene in HCC correlates with poorer patient survival outcomes, suggesting its potential as a prognostic biomarker and a target for personalized therapy, particularly in strategies combining immunotherapy and anti-TRP agents.

Investigating Contributions of Canonical Transient Receptor Potential Channel 3 to Hippocampal Hyperexcitability and Seizure-Induced Neuronal Cell Death.

Canonical transient receptor potential channel 3 (TRPC3) is the most abundant TRPC channel in the brain and is highly expressed in all subfields of the hippocampus. Previous studies have suggested that TRPC3 channels may be involved in the hyperexcitability of hippocampal pyramidal neurons and seizures. Genetic ablation of TRPC3 channel expression reduced the intensity of pilocarpine-induced status epilepticus (SE). However, the underlying cellular mechanisms remain unexplored and the contribution of TRPC3 channels to SE-induced neurodegeneration is not determined. In this study, we investigated the contribution of TRPC3 channels to the electrophysiological properties of hippocampal pyramidal neurons and hippocampal synaptic plasticity, and the contribution of TRPC3 channels to seizure-induced neuronal cell death. We found that genetic ablation of TRPC3 expression did not alter basic electrophysiological properties of hippocampal pyramidal neurons and had a complex impact on epileptiform bursting in CA3. However, TRPC3 channels contribute significantly to long-term potentiation in CA1 and SE-induced neurodegeneration. Our results provided further support for therapeutic potential of TRPC3 inhibitors and raised new questions that need to be answered by future studies.

Post-traumatic stress disorder: the role of the amygdala and potential therapeutic interventions - a review.

Post-traumatic stress disorder (PTSD) is a psychiatric disorder triggered by exposure to a life-threatening or sexually violent traumatic event, and is characterized by symptoms involving intrusive re-experiencing, persistent avoidance of associated stimuli, emotional and cognitive disturbances, and hyperarousal for long periods after the trauma has occurred. These debilitating symptoms induce occupational and social impairments that contribute to a significant clinical burden for PTSD patients, and substantial socioeconomic costs, reaching approximately $20,000 dollars per individual with PTSD each year in the US. Despite increased translational research focus in the field of PTSD, the development of novel, effective pharmacotherapies for its treatment remains an important unmet clinical need. In this review, we summarize the evidence implicating dysfunctional activity of the amygdala in the pathophysiology of PTSD. We identify the transient receptor potential canonical (TRPC) ion channels as promising drug targets given their distribution in the amygdala, and evidence from animal studies demonstrating their role in fear response modulation. We discuss the evidence-based pharmacotherapy and psychotherapy treatment approaches for PTSD. In view of the prevalence and economic burden associated with PTSD, further investigation is warranted into novel treatment approaches based on our knowledge of the involvement of brain circuitry and the role of the amygdala in PTSD, as well as the potential added value of combined pharmacotherapy and psychotherapy to better manage PTSD symptoms.

A novel gain-of-function mutation in transient receptor potential C6 that causes podocytes injury.

Podocyte injury plays a vital role in focal segmental glomerulosclerosis (FSGS), and apoptosis is one of its mechanisms. The transient receptor potential channel 6 (TRPC6) is highly expressed in podocytes and mutations mediate podocyte injury. We found TRPC6 gene mutation (N110S) was a new mutation and pathogenic in the preliminary clinical work. The purpose of this study was to investigate the potential mechanism of mutation in TRPC6 (TRPC6-N110S) in the knock-in gene mouse model and in immortalized mouse podocytes (MPC5). Transmission electron microscopy was used to evaluate renal injury morphology. We measured 24-hour urinary albumin-to-creatinine ratios and major biochemical parameters such as serum albumin, urea nitrogen, and total cholesterol. The results of CCK-8 assay and apoptosis experiments showed that the TRPC6-N110S overexpression group had slower proliferative activity and increased apoptosis than the control group. FluO-3 assay revealed increased calcium influx in the TRPC6-N110S overexpression group. Podocin level was decreased in TRPC6-N110S group, while TRPC6 and desmin levels were increased in TRPC6-N110S group. The 24 h uACR at 6 weeks was significantly higher in the pure-zygotes group than in the WT and heterozygotes groups, and this difference was found at 8 and 10 weeks.TRPC6 levels showed no significant difference between homozygote and WT mice. Compared to homozygote group, expression of podocin and nephrin were increased in WT, but levels of desmin was decreased in WT. Our results suggest that this new mutation causes podocyte injury probably by enhancing calcium influx and podocyte apoptosis, accompanied by increased proteinuria and decreased expression of nephrin and podocin.

TRPC absence induces pro-inflammatory macrophage polarization to promote obesity and exacerbate colorectal cancer.

During the past half-century, although numerous interventions for obesity have arisen, the condition's prevalence has relentlessly escalated annually. Obesity represents a substantial public health challenge, especially due to its robust correlation with co-morbidities, such as colorectal cancer (CRC), which often thrives in an inflammatory tumor milieu. Of note, individuals with obesity commonly present with calcium and vitamin D insufficiencies. Transient receptor potential canonical (TRPC) channels, a subclass within the broader TRP family, function as critical calcium transporters in calcium-mediated signaling pathways. However, the exact role of TRPC channels in both obesity and CRC pathogenesis remains poorly understood. This study set out to elucidate the part played by TRPC channels in obesity and CRC development using a mouse model lacking all seven TRPC proteins (TRPC HeptaKO mice). Relative to wild-type counterparts, TRPC HeptaKO mice manifested severe obesity, evidenced by significantly heightened body weights, augmented weights of epididymal white adipose tissue (eWAT) and inguinal white adipose tissue (iWAT), increased hepatic lipid deposition, and raised serum levels of total cholesterol (T-CHO) and low-density lipoprotein cholesterol (LDL-C). Moreover, TRPC deficiency was accompanied by an decrease in thermogenic molecules like PGC1-α and UCP1, alongside a upsurge in inflammatory factors within adipose tissue. Mechanistically, it was revealed that pro-inflammatory factors originating from inflammatory macrophages in adipose tissue triggered lipid accumulation and exacerbated obesity-related phenotypes. Intriguingly, considering the well-established connection between obesity and disrupted gut microbiota balance, substantial changes in the gut microbiota composition were detected in TRPC HeptaKO mice, contributing to CRC development. This study provides valuable insights into the role and underlying mechanisms of TRPC deficiency in obesity and its related complication, CRC. Our findings offer a theoretical foundation for the prevention of adverse effects associated with TRPC inhibitors, potentially leading to new therapeutic strategies for obesity and CRC prevention.

TRPC6 Knockout Alleviates Renal Fibrosis through PI3K/AKT/GSK3B Pathway.

Renal fibrosis is the ultimate pathway of various forms of acute and chronic kidney damage. Notably, the knockout of transient receptor potential channel 6 (TRPC6) has shown promise in alleviating renal fibrosis. However, the regulatory impact of TRPC6 on renal fibrosis remains unclear. In vivo, TRPC6 knockout (TRPC6-/-) mice and age-matched 129 SvEv (WT) mice underwent unilateral renal ischemia-reperfusion (uIR) injury surgery on the left renal pedicle or sham operation. Kidneys and serum were collected on days 7, 14, 21, and 28 after euthanasia. In vitro, primary tubular epithelial cells (PTECs) were isolated from TRPC6-/- and WT mice, followed by treatment with transforming growth factor β1 (TGFβ1) for 72 h. The anti-fibrotic effect of TRPC6-/- and the underlying mechanisms were assessed through hematoxylin-eosin staining, Masson staining, immunostaining, qRT-PCR, and Western blotting. Increased TRPC6 expression was observed in uIR mice and PTECs treated with TGFβ1. TRPC6-/- alleviated renal fibrosis by reducing the expression of fibrotic markers (Col-1, α-SMA, and vimentin), as well as decreasing the apoptosis and inflammation of PTECs during fibrotic progression both in vivo and in vitro. Additionally, we found that the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase 3 beta (GSK3β) signaling pathway, a pivotal player in renal fibrosis, was down-regulated following TRPC6 deletion. These results suggest that the ablation of TRPC6 may mitigate renal fibrosis by inhibiting the apoptosis and inflammation of PTECs through down-regulation of the PI3K/AKT/GSK3β pathway. Targeting TRPC6 could be a novel therapeutic strategy for preventing chronic kidney disease.

CYP24A1 and TRPC3 Gene Expression in Kidneys and Their Involvement in Calcium and Phosphate Metabolism in Laying Hens.

Ca and P homeostasis across the egg-laying cycle is a complex process involving absorption in the small intestine, reabsorption/excretion in the kidneys, and eggshell gland secretion. Diets with inadequate calcium and phosphorus can interfere with their absorption and digestibility, resulting in eggshell quality losses and reduced productive life, affecting egg production and welfare. A better understanding of gene expression profiles in the kidneys of laying hens during the late egg-laying period could clarify the renal role in mineral metabolism at this late stage. Therefore, the performance, egg quality and bone integrity-related traits, and expression profiles of kidney candidate genes were evaluated in 73-week-old laying hens receiving different Ca and P ratios in their diet: a high Ca/P ratio (HR, 22.43), a low ratio (LR, 6.71), and a medium ratio (MR, 11.43). The laying hens receiving the HR diet had improved egg production and eggshell quality traits compared to the other two groups. Humerus length was shorter in the HR than in the other groups. The CYP24A1 and TRPC3 genes were differentially expressed (p.adj ≤ 0.05) among the groups. Therefore, their expression profiles could be involved in calcium and phosphate transcellular transport in 73-week-old laying hens as a way to keep mineral absorption at adequate levels.

Pathophysiological significance and modulation of the transient receptor potential canonical 3 ion channel.

Transient receptor potential canonical 3 (TRPC3) protein belongs to the TRP family of nonselective cation channels. Its activation occurs by signaling through a G protein-coupled receptor (GPCR) and a phospholipase C-dependent (PLC) pathway. Perturbations in the expression of TRPC3 are associated with a plethora of pathophysiological conditions responsible for disorders of the cardiovascular, immune, and central nervous systems. The recently solved cryo-EM structure of TRPC3 provides detailed inputs about the underlying mechanistic aspects of the channel, which in turn enables more efficient ways of designing small-molecule modulators. Pharmacologically targeting TRPC3 in animal models has demonstrated great efficacy in treating diseases including cancers, neurological disorders, and cardiovascular diseases. Despite extensive scientific evidence supporting some strong correlations between the expression and activity of TRPC3 and various pathophysiological conditions, therapeutic strategies based on its pharmacological modulations have not led to clinical trials. The development of small-molecule TRPC3 modulators with high safety, sufficient brain penetration, and acceptable drug-like profiles remains in progress. Determining the pathological mechanisms for TRPC3 involvement in human diseases and understanding the requirements for a drug-like TRPC3 modulator will be valuable in advancing small-molecule therapeutics to future clinical trials. In this review, we provide an overview of the origin and activation mechanism of TRPC3 channels, diseases associated with irregularities in their expression, and new development in small-molecule modulators as potential therapeutic interventions for treating TRPC3 channelopathies.

Canonical transient receptor potential channels and hypothalamic control of homeostatic functions.

Recent molecular biological and electrophysiological studies have identified multiple transient receptor potential (TRP) channels in hypothalamic neurons as critical modulators of homeostatic functions. In particular, the canonical transient receptor potential channels (TRPCs) are expressed in hypothalamic neurons that are vital for the control of fertility and energy homeostasis. Classical neurotransmitters such as serotonin and glutamate and peptide neurotransmitters such as kisspeptin, neurokinin B and pituitary adenylyl cyclase-activating polypeptide signal through their cognate G protein-coupled receptors to activate TPRC 4, 5 channels, which are essentially ligand-gated calcium channels. In addition to neurotransmitters, circulating hormones like insulin and leptin signal through insulin receptor (InsR) and leptin receptor (LRb), respectively, to activate TRPC 5 channels in hypothalamic arcuate nucleus pro-opiomelanocortin (POMC) and kisspeptin (arcuate Kiss1 [Kiss1ARH]) neurons to have profound physiological (excitatory) effects. Besides its overt depolarizing effects, TRPC channels conduct calcium ions into the cytoplasm, which has a plethora of downstream effects. Moreover, not only the expression of Trpc5 mRNA but also the coupling of receptors to TRPC 5 channel opening are regulated in different physiological states. In particular, the mRNA expression of Trpc5 is highly regulated in kisspeptin neurons by circulating estrogens, which ultimately dictates the firing pattern of kisspeptin neurons. In obesity states, InsRs are "uncoupled" from opening TRPC 5 channels in POMC neurons, rendering them less excitable. Therefore, in this review, we will focus on the critical role of TRPC 5 channels in regulating the excitability of Kiss1ARH and POMC neurons in different physiological and pathological states.

TRPC3 Is Downregulated in Primary Hyperparathyroidism.

Transient receptor potential canonical sub-family channel 3 (TRPC3) is considered to play a critical role in calcium homeostasis. However, there are no established findings in this respect with regard to TRPC6. Although the parathyroid gland is a crucial organ in calcium household regulation, little is known about the protein distribution of TRPC channels-especially TRPC3 and TRPC6-in this organ. Our aim was therefore to investigate the protein expression profile of TRPC3 and TRPC6 in healthy and diseased human parathyroid glands. Surgery samples from patients with healthy parathyroid glands and from patients suffering from primary hyperparathyroidism (pHPT) were investigated by immunohistochemistry using knockout-validated antibodies against TRPC3 and TRPC6. A software-based analysis similar to an H-score was performed. For the first time, to our knowledge, TRPC3 and TRPC6 protein expression is described here in the parathyroid glands. It is found in both chief and oxyphilic cells. Furthermore, the TRPC3 staining score in diseased tissue (pHPT) was statistically significantly lower than that in healthy tissue. In conclusion, TRPC3 and TRPC6 proteins are expressed in the human parathyroid gland. Furthermore, there is strong evidence indicating that TRPC3 plays a role in pHPT and subsequently in parathyroid hormone secretion regulation. These findings ultimately require further research in order to not only confirm our results but also to further investigate the relevance of these channels and, in particular, that of TRPC3 in the aforementioned physiological functions and pathophysiological conditions.