High glucose reduces expression of podocin in cultured human podocytes by stimulating TRPC6

Downregulating lncRNA MIAT attenuates apoptosis of podocytes exposed to high glucose

AIMS

Diabetic nephropathy (DN), a destructive complication of diabetes mellitus (DM), is one of the leading causes of end-stage renal disease (ESRD). This study aimed to investigate the role of long non-coding RNA (lncRNA) MIAT in high-glucose (HG)-induced podocyte injury associated with DN.

METHODS

Three human kidney podocyte (HKP) cultures were treated with HG to mimic DN. Expression of lncRNA MIAT, podocyte-specific and injury-related proteins, and apoptosis were assessed before and after MIAT knockdown using MIAT shRNAs.

RESULTS

MIAT expression was upregulated in HKPs in response to glucose stress. HG treatment resulted in a significant increase in the apoptotic rate, Bax level, and levels of injury-related proteins desmin, fibroblast-specific protein 1 (FSP-1), and smooth muscle α-actin (α-SMA), and a significant reduction in Bcl-2 levels and the levels of podocyte-specific proteins synaptopodin and podocin. Transfection of HKPs with shRNAs significantly reduced MIAT levels (p < 0.05) and attenuated apoptosis in HG-medium. Correspondingly, the levels of synaptopodin and podocin were upregulated, and desmin, FSP-1, and α-SMA were reduced (p < 0.05). Western blot analysis also showed that anti-apoptotic active caspase-3 and Bax and proapoptotic Bcl-2 were elevated and decreased, respectively, after MIAT knockdown, suggesting that apoptosis pathways are deactivated after MIAT downregulation.

CONCLUSIONS

High glucose upregulates MIAT level in HKPs and induces cellular injury. Knockdown of MIAT alleviates the injury likely via deactivating apoptosis pathways.

The Mechanism of Hyperglycemia-Induced Renal Cell Injury in Diabetic Nephropathy Disease: An Update

Diabetic Nephropathy (DN) is a serious complication of type I and II diabetes. It develops from the initial microproteinuria to end-stage renal failure. The main initiator for DN is chronic hyperglycemia. Hyperglycemia (HG) can stimulate the resident and non-resident renal cells to produce humoral mediators and cytokines that can lead to functional and phenotypic changes in renal cells and tissues, interference with cell growth, interacting proteins, advanced glycation end products (AGEs), etc., ultimately resulting in glomerular and tubular damage and the onset of kidney disease. Therefore, poor blood glucose control is a particularly important risk factor for the development of DN. In this paper, the types and mechanisms of DN cell damage are classified and summarized by reviewing the related literature concerning the effect of hyperglycemia on the development of DN. At the cellular level, we summarize the mechanisms and effects of renal damage by hyperglycemia. This is expected to provide therapeutic ideas and inspiration for further studies on the treatment of patients with DN.

Ion channels and channelopathies in glomeruli

An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.

Urolithins Modulate the Viability, Autophagy, Apoptosis, and Nephrin Turnover in Podocytes Exposed to High Glucose

Urolithins are bioactive compounds generated in human and animal intestines because of the bacterial metabolism of dietary ellagitannins (and their constituent, ellagic acid). Due to their multidirectional effects, including anti-inflammatory, antioxidant, anti-cancer, neuroprotective, and antiglycative properties, urolithins are potential novel therapeutic agents. In this study, while considering the future possibility of using urolithins to improve podocyte function in diabetes, we assessed the results of exposing mouse podocytes cultured in normal (NG, 5.5 mM) and high (HG, 25 mM) glucose concentrations to urolithin A (UA) and urolithin B (UB). Podocytes metabolized UA to form glucuronides in a time-dependent manner; however, in HG conditions, the metabolism was lower than in NG conditions. In HG milieu, UA improved podocyte viability more efficiently than UB and reduced the reactive oxygen species level. Both types of urolithins showed cytotoxic activity at high (100 µM) concentration. The UA upregulated total and surface nephrin expression, which was paralleled by enhanced nephrin internalization. Regulation of nephrin turnover was independent of ambient glucose concentration. We conclude that UA affects podocytes in different metabolic and functional aspects. With respect to its pro-survival effects in HG-induced toxicity, UA could be considered as a potent therapeutic candidate against diabetic podocytopathy.

Nephrin expression in human epidermal keratinocytes and its implication in poor wound closure

Nephrin is a type-1 transmembrane protein and a component of the slit diaphragm renal-filtration barrier. It has several functions in actin remodeling and cell-cell adhesion. Nephrin is principally located in the kidney glomerulus, but several studies have reported that nephrin is found in the pancreas, brain, and placenta. However, nephrin expression and its role in human skin have not yet been reported. First, using single-cell RNA sequencing, immunohistochemistry, and immuno-electron microscopy, nephrin expression was confirmed in human-skin epidermal keratinocytes. Nephrin expression colocalized with the expression of zonula occludens-1 in keratinocytes and was closely related to keratinocyte cell density, proliferation, and migration. High glucose treatment decreased nephrin expression and compromised keratinocyte cell migration without yes-associated protein nuclear entry. This reduced cell migration under high glucose conditions was improved in nephrin-overexpressing keratinocytes. Nephrin was highly expressed on the margins of re-epithelized epidermis based on in vivo mice and ex vivo human skin wound models. The results demonstrate that nephrin is expressed in human-skin keratinocytes and functions in cell adhesion, proliferation, and migration. In conclusion, this study suggests that nephrin may have a variety of physiological roles in human skin.

Enhanced Orai1-mediated store-operated Ca2+ channel/calpain signaling contributes to high glucose-induced podocyte injury

Podocyte injury induced by hyperglycemia is the main cause of kidney dysfunction in diabetic nephropathy. However, the underlying mechanism is unclear. Store-operated Ca2+ entry (SOCE) regulates a diversity of cellular processes in a variety of cell types. Calpain, a Ca2+-dependent cysteine protease, was recently shown to be involved in podocyte injury. In the present study, we sought to determine whether increased SOCE contributed to high glucose (HG)-induced podocyte injury through activation of the calpain pathway. In cultured human podocytes, whole-cell patch clamp indicated the presence of functional store-operated Ca2+ channels, which are composed of Orai1 proteins and mediate SOCE. Western blots showed that HG treatment increased the protein abundance of Orai1 in a dose-dependent manner. Consistently, calcium imaging experiments revealed that SOCE was significantly enhanced in podocytes following HG treatment. Furthermore, HG treatment caused overt podocyte F-actin disorganization as well as a significant decrease in nephrin protein abundance, both of which are indications of podocyte injury. These podocyte injury responses were significantly blunted by both pharmacological inhibition of Orai1 using the small molecule inhibitor BTP2 or by genetic deletion of Orai1 using CRISPR-Cas9 lentivirus. Moreover, activation of SOCE by thapsigargin, an inhibitor of Ca2+ pump on the endoplasmic/sarcoplasmic reticulum membrane, significantly increased the activity of calpain, which was inhibited by BTP2. Finally, the calpain-1/calpain-2 inhibitor calpeptin significantly blunted the nephrin protein reduction induced by HG treatment. Taken together, our results suggest that enhanced signaling via an Orai1/SOCE/Calpain axis contributes to HG-induced podocyte injury.

Cortex Mori Radicis attenuates streptozotocin-induced diabetic renal injury in mice via regulation of transient receptor potential canonical channel 6

OBJECTIVE

Cortex Mori Radicis (CMR) has been reported to possess anti-pyretic, anti-convulsant, anti-allergic, anti-inflammatory, and anti-diabetic effects. In this study, we aimed to investigate the effect of CMR on streptozotocin (STZ)-induced diabetic renal injury in mice and explore the underlying mechanism.

METHODS

Mice were gavaged with different doses of CMR for continuous 7 days. Then, STZ (50 mg/kg) was applied to induce renal injury associated with type 1 diabetes. Firstly, blood glucose levels and metabolic parameters were evaluated, including weight, food intake, and excrement. HE and PAS staining were performed to present renal histological changes. Renal inflammation, fibrosis, and oxidative stress were assayed by real time PCR and ELISA, separately. Additionally, podocyte-related markers, such as nephrin and wilms' tumor-1 (WT-1) were detected by immunohistochemical staining and Western blot separately. Lastly, expression of transient receptor potential canonical channel 6 (TRPC6) and activation of MAPK signaling pathways were assayed.

RESULTS

CMR pretreatment significantly lowered the blood glucose levels, suppressed renal inflammation, fibrosis and oxidative stress, and relieved renal pathological injury, accompanying the inhibition of nephrin and WT-1 expression in STZ-induced diabetic mice. Moreover, CMR decreased the expression of TRPC6 and suppressed phosphorylation of ERK, but not P38 MAPK and JNK. Notably, the application of hyperforin, a specific activator of TRPC6, significantly abrogated the hypoglycemic effect of CMR and reversed the suppression of CMR on TRPC6 expression and ERK activation in the diabetic mice.

CONCLUSION

Our findings indicated that CMR attenuated early renal injury in STZ-induced diabetic mice through inhibiting ERK signaling via regulation of TRPC6, which suggests that CMR can be considered as a promising candidate for the management of diabetes-related renal complications.

Transient receptor potential cation channel 6 contributes to kidney injury induced by diabetes and hypertension

Diabetes mellitus (DM) and hypertension (HTN) are major risk factors for chronic kidney injury, together accounting for >70% of end-stage renal disease. In this study, we assessed whether DM and HTN interact synergistically to promote kidney dysfunction and whether transient receptor potential cation channel 6 (TRPC6) contributes to this synergism. In wild-type (WT; B6/129s background) and TRPC6 knockout (KO) mice, DM was induced by streptozotocin injection to increase fasting glucose levels to 250-350 mg/dL. HTN was induced by aorta constriction (AC) between the renal arteries. AC increased blood pressure (BP) by ∼25 mmHg in the right kidney (above AC), whereas BP in the left kidney (below AC) returned to near normal after 8 wk, with both kidneys exposed to the same levels of blood glucose, circulating hormones, and neural influences. Kidneys of WT mice exposed to DM or HTN alone had only mild glomerular injury and urinary albumin excretion. In contrast, WT kidneys exposed to DM plus HTN (WT-DM + AC mice) for 8 wk had much greater increases in albumin excretion and histological injury. Marked increased apoptosis was also observed in the right kidneys of WT-DM + AC mice. In contrast, in TRPC6 KO mice with DM + AC, right kidneys exposed to the same levels of high BP and high glucose had lower albumin excretion and less glomerular damage and apoptotic cell injury compared with right kidneys of WT-DM + AC mice. Our results suggest that TRPC6 may contribute to the interaction of DM and HTN to promote kidney dysfunction and apoptotic cell injury.NEW & NOTEWORTHY A major new finding of this study is that the combination of moderate diabetes and hypertension promoted marked renal dysfunction, albuminuria, and apoptotic cell injury, and that these effects were greatly ameliorated by transient receptor potential cation channel 6 deficiency. These results suggest that transient receptor potential cation channel 6 may play an important role in contributing to the interaction of diabetes and hypertension to promote kidney injury.

Atractylodin inhibits fructose-induced human podocyte hypermotility via anti-oxidant to down-regulate TRPC6/p-CaMK4 signaling

High fructose has been reported to drive glomerular podocyte oxidative stress and then induce podocyte foot process effacement in vivo, which could be partly regarded as podocyte hypermotility in vitro. Atractylodin possesses anti-oxidative effect. The aim of this study was to explore whether atractylodin prevented against fructose-induced podocyte hypermotility via anti-oxidative property. In fructose-exposed conditionally immortalized human podocytes, we found that atractylodin inhibited podocyte hypermotility, and up-regulated slit diaphragm proteins podocin and nephrin, and cytoskeleton protein CD2-associated protein (CD2AP), α-Actinin-4 and synaptopodin expression, which were consistent with its anti-oxidative activity evidenced by up-regulation of catalase (CAT) and superoxide dismutase (SOD) 1 expression, and reduction of reactive oxygen species (ROS) production. Atractylodin also significantly suppressed expression of transient receptor potential channels 6 (TRPC6) and phosphorylated Ca²⁺/calmodulin-dependent protein kinase IV (CaMK4) in cultured podocytes with fructose exposure. Additionally, in fructose-exposed podocytes, CaMK4 siRNA up-regulated synaptopodin and reduced podocyte hypermotility, whereas, silencing of TRPC6 by siRNA decreased p-CaMK4 expression, inhibited podocyte hypermotility, showing TRPC6/p-CaMK4 signaling activation in podocyte hypermotility under fructose condition. Just like atractylodin, antioxidant N-acetyl-L-cysteine (NAC) could inhibit TRPC6/p-CaMK4 signaling activation to reduce fructose-induced podocytes hypermotility. These results first demonstrated that the anti-oxidative property of atractylodin may contribute to the suppression of podocyte hypermotility via inhibiting TRPC6/p-CaMK4 signaling and restoring synaptopodin expression abnormality.

Tacrolimus Protects Podocytes from Apoptosis via Downregulation of TRPC6 in Diabetic Nephropathy

Podocyte injury plays an important role in diabetic nephropathy (DN), and apoptosis is one of its mechanisms. The transient receptor potential channel 6 (TRPC6) is expressed in podocytes and mediates podocyte injury induced by high glucose levels. Tacrolimus is a novel immunosuppressive agent that is reported to play an important role in podocyte protection. The purpose of this study was to investigate the potential mechanism of podocyte protection by tacrolimus in a type 2 diabetic mellitus (T2DM) rat model and in immortalized mouse podocytes (MPC5). Transmission electron microcopy was used to evaluate renal injury morphology. After treatment with FK506, we measured 24-hour urinary albumin-to-creatinine ratios and creatinine clearance rates as well as major biochemical parameters such as glucose, insulin, serum creatinine, urea nitrogen, total cholesterol, triglycerides, alanine transaminase, and aspartate aminotransferase. Nephrin and TRPC6 protein expression and podocyte apoptotic rates in vivo and in vitro were measured using immunohistochemical staining, TUNEL assays, and flow cytometry, respectively. Western blot was used to measure expression of cleaved-caspase-3 and bax/bcl-2. Exposed to high glucose (HG), DM rats exhibited disrupted biochemical conditions and impaired podocyte structure. Decreased expression of nephrin and increased expression of TRPC6, cleaved-caspase-3, and bax/bcl-2 ratios were found in podocytes, along with higher apoptotic percentage, while tacrolimus intervention counteracted the effect of HG on podocytes. Our results suggest that tacrolimus protects podocytes during the progression of type 2 diabetic nephropathy, possibly ameliorating podocyte apoptosis by downregulating the expression of TRPC6.

FOXA1 Suppresses SATB1 Transcription and Inactivates the Wnt/β-Catenin Pathway to Alleviate Diabetic Nephropathy in a Mouse Model

OBJECTIVE

Diabetic nephropathy (DN) represents the most common diabetic complication that may lead to end-stage renal disease. This work focused on the effect of FOXA1 on the DN development and the molecular mechanism.

METHODS

A mouse model of DN was induced by high-fat diets and streptozotocin. The concentrations of blood glucose and urinary protein in mice, and the pathological changes in mouse kidney tissues were determined. A podocyte cell line MPC-5 was treated with high glucose (HG) to mimic a DN-like condition in vitro. FOXA1 and SATB1 were overexpressed in HG-treated MPC-5 cells and in DN mice to explore their effects on cell proliferation and apoptosis, and on pathological changes in mouse kidney tissues. The binding relationship between FOXA1 and STAB1 was predicted and validated. Activation of the Wnt/β-catenin pathway was detected.

RESULTS

FOXA1 was poorly expressed in the kidney tissues of DN mice. Overexpression of FOXA1 reduced the concentrations of fasting blood glucose and 24-h urinary protein in mice. It also suppressed the accumulation of glomerular mesangial matrix and hyperplasia of glomerular basement membrane, and reduced collagen deposition and interstitial fibrosis in mouse kidney. Also, FOXA1 reduced HG-induced apoptosis of MPC-5 cells. FOXA1 bound to the promoter region of SATB1 for transcription suppression. Overexpression of SATB1 activated the Wnt/β-catenin pathway and blocked the protective roles of FOXA1 in DN mice and in HG-treated MPC-5 cells.

CONCLUSION

This study demonstrated that FOXA1 transcriptionally suppresses SATB1 expression and inactivates the Wnt/β-catenin signaling pathway, thereby inhibiting podocyte apoptosis and DN progression.

Diabetic Kidney Disease, Endothelial Damage, and Podocyte-Endothelial Crosstalk

Diabetes-related complications are a significant source of morbidity and mortality worldwide. Diabetic kidney disease is a frequent microvascular complication and a primary cause of kidney failure in patients with diabetes. The glomerular filtration barrier is composed of 3 layers: the endothelium, glomerular basement membrane, and podocytes. Podocytes and the endothelium communicate through molecular crosstalk to maintain filtration at the glomerular filtration barrier. Chronic hyperglycemia affects all 3 layers of the glomerular filtration barrier, as well as the molecular crosstalk that occurs between the 2 cellular layers. One of the earliest events following chronic hyperglycemia is endothelial cell dysfunction. Early endothelial damage is associated with progression of diabetic kidney disease. However, current therapies are based in controlling glycemia and arterial blood pressure without targeting endothelial dysfunction. Disruption of the endothelial cell layer also alters the molecular crosstalk that occurs between the endothelium and podocytes. This review discusses both the physiologic and pathologic communication that occurs at the glomerular filtration barrier. It examines how these signaling components contribute to podocyte foot effacement, podocyte detachment, and the progression of diabetic kidney disease.

Low-glucose-sensitive TRPC6 dysfunction drives hypoglycemia-induced cognitive impairment in diabetes

Background

Recurrent moderate hypoglycemia (RH), a major adverse effect of hypoglycemic therapy in diabetic patients, is one of the main risk factors for cognitive impairment and dementia. Transient receptor potential canonical channel 6 (TRPC6) is a potential therapeutic target for Alzheimer's disease (AD) and its expression is highly regulated by glucose concentration.

Objective

To investigate whether RH regulates the expression of TRPC6 in brain and whether TRPC6 dysfunction can drive hypoglycemia‐associated cognitive impairment in diabetes, and reveal the underlying mechanism.

Methods

Histological staining, in vivo two‐photon Ca²⁺ imaging, and behavioral tests were used to measure neuronal death, brain network activity, and cognitive function in mice, respectively. High‐resolution respirometry and transmission electron microscope were used to assess mitochondrial structure and function. Intracellular calcium measurement and molecular biology techniques were conducted to uncover the underlying mechanism.

Results

Here, we report that the expression of TRPC6 in hippocampus was specifically repressed by RH in streptozocin‐induced type 1 diabetic mice, but not in nondiabetic mice. TRPC6 knockout directly leads to neuron loss, neuronal activity, and cognitive function impairment under diabetic condition, the degree of which is similar to that of RH. Activation of TRPC6 with hyperforin substantially improved RH‐induced cognitive impairment. Mechanistically, TRPC6 inhibited mitochondrial fission in the hippocampus of diabetic mice undergoing RH episodes by activating adenosine 5‘‐monophosphate‐activated protein kinase, and TRPC6‐mediated cytosolic calcium influx was required for this process. Clinically, dysfunction of TRPC6 was closely associated with cognitive impairment in type 2 diabetic patients with RH.

Conclusions

Our results indicate that TRPC6 is a critical sensitive cation channel to hypoglycemia and is a promising target to prevent RH‐induced cognitive impairment by properly orchestrating the mitochondrial dynamics in diabetic patients.

Role of opioid signaling in kidney damage during the development of salt-induced hypertension

Stimulation of kappa opioid receptors modulates calcium influx via TRPC6 channels in podocytes, which ultimately compromises the integrity of the glomerular filtration barrier and promotes a marked worsening of blood pressure control and renal damage.

Opioid use is associated with predictors of poor cardiorenal outcomes. However, little is known about the direct impact of opioids on podocytes and renal function, especially in the context of hypertension and CKD. We hypothesize that stimulation of opioid receptors (ORs) contributes to dysregulation of intracellular calcium ([Ca²⁺]_i) homeostasis in podocytes, thus aggravating the development of renal damage in hypertensive conditions. Herein, freshly isolated glomeruli from Dahl salt-sensitive (SS) rats and human kidneys, as well as immortalized human podocytes, were used to elucidate the contribution of specific ORs to calcium influx. Stimulation of κ-ORs, but not μ-ORs or δ-ORs, evoked a [Ca²⁺]_i transient in podocytes, potentially through the activation of TRPC6 channels. κ-OR agonist BRL52537 was used to assess the long-term effect in SS rats fed a high-salt diet. Hypertensive rats chronically treated with BRL52537 exhibited [Ca²⁺]_i overload in podocytes, nephrinuria, albuminuria, changes in electrolyte balance, and augmented blood pressure. These data demonstrate that the κ-OR/TRPC6 signaling directly influences podocyte calcium handling, provoking the development of kidney injury in the opioid-treated hypertensive cohort.

Regulation of the Actin Cytoskeleton in Podocytes

Podocytes are an integral part of the glomerular filtration barrier, a structure that prevents filtration of large proteins and macromolecules into the urine. Podocyte function is dependent on actin cytoskeleton regulation within the foot processes, structures that link podocytes to the glomerular basement membrane. Actin cytoskeleton dynamics in podocyte foot processes are complex and regulated by multiple proteins and other factors. There are two key signal integration and structural hubs within foot processes that regulate the actin cytoskeleton: the slit diaphragm and focal adhesions. Both modulate actin filament extension as well as foot process mobility. No matter what the initial cause, the final common pathway of podocyte damage is dysregulation of the actin cytoskeleton leading to foot process retraction and proteinuria. Disruption of the actin cytoskeleton can be due to acquired causes or to genetic mutations in key actin regulatory and signaling proteins. Here, we describe the major structural and signaling components that regulate the actin cytoskeleton in podocytes as well as acquired and genetic causes of actin dysregulation.

The Rab-Rabphilin system in injured human podocytes stressed by glucose overload and angiotensin II

Kidney injury in hypertension and diabetes entails, among in other structures, damage in a key cell of the glomerular filtration barrier, the podocyte. Podocytes are polarized and highly differentiated cells in which vesicular transport, partly driven by Rab GTPases, is a relevant process. The aim of the present study was to analyze Rab GTPases of the Rab-Rabphilin system in human immortalized podocytes and the impact of high glucose and angiotensin II. Furthermore, alterations of the system in urine cell pellets from patients with hypertension and diabetes were studied. Apoptosis was analyzed in podocytes, and mRNA level quantification, Western blot analysis, and immunofluorescence were developed to quantify podocyte-specific molecules and Rab-Rabphilin components (Rab3A, Rab27A, and Rabphilin3A). Quantitative RT-PCR was performed on urinary cell pellet from patients. The results showed that differentiated cells had reduced protein levels of the Rab-rabphillin system compared with undifferentiated cells. After glucose overload and angiotensin II treatment, apoptosis was increased and podocyte-specific proteins were reduced. Rab3A and Rab27A protein levels were increased under glucose overload, and Rabphilin3A decreased. Furthermore, this system exhibited higher levels under stress conditions in a manner of angiotensin II dose and time treatment. Immunofluorescence imaging indicated different expression patterns of podocyte markers and Rab27A under treatments. Finally, Rab3A and Rab27A were increased in patient urine pellets and showed a direct relationship with albuminuria. Collectively, these results suggest that the Rab-Rabphilin system could be involved in the alterations observed in injured podocytes and that a mechanism may be activated to reduce damage through the vesicular transport enhancement directed by this system.

TRPC Channels in Proteinuric Kidney Diseases

Over a decade ago, mutations in the gene encoding TRPC6 (transient receptor potential cation channel, subfamily C, member 6) were linked to development of familial forms of nephrosis. Since this discovery, TRPC6 has been implicated in the pathophysiology of non-genetic forms of kidney disease including focal segmental glomerulosclerosis (FSGS), diabetic nephropathy, immune-mediated kidney diseases, and renal fibrosis. On the basis of these findings, TRPC6 has become an important target for the development of therapeutic agents to treat diverse kidney diseases. Although TRPC6 has been a major focus for drug discovery, more recent studies suggest that other TRPC family members play a role in the pathogenesis of glomerular disease processes and chronic kidney disease (CKD). This review highlights the data implicating TRPC6 and other TRPC family members in both genetic and non-genetic forms of kidney disease, focusing on TRPC3, TRPC5, and TRPC6 in a cell type (glomerular podocytes) that plays a key role in proteinuric kidney diseases.