Gain-of-function Mutations in Transient Receptor Potential C6 (TRPC6) Activate Extracellular Signal-regulated Kinases 1/2 (ERK1/2)

Gain-of-function mutations in the transient receptor potential (TRP) cation channel subfamily C member 6 ( TRPC6) gene and mutations in the NPHS2 gene encoding podocin result in nephrotic syndromes. The purpose of this study was to determine the functional significance of biochemical interactions between these proteins. We observed that gating of TRPC6 channels in podocytes is markedly mechanosensitive and can be activated by hyposmotic stretch or indentation of the plasma membrane. Stretch activation of cationic currents was blocked by small interfering RNA knockdown of TRPC6, as well as by SKF-96365 or micromolar La3+. Stretch activation of podocyte TRPC6 persisted in the presence of inhibitors of phospholipase C (U-73122) and phospholipase A2 (ONO-RS-082). Robust stretch responses also persisted when recording electrodes contained guanosine 5′- O-(2-thiodiphosphate) at concentrations that completely suppressed responses to ANG II. Stretch responses were enhanced by cytochalasin D but were abolished by the peptide GsMTx4, suggesting that forces are transmitted to the channels through the plasma membrane. Podocin and TRPC6 interact at their respective COOH termini. Knockdown of podocin markedly increased stretch-evoked activation of TRPC6 but nearly abolished TRPC6 activation evoked by a diacylglycerol analog. These data suggest that podocin acts as a switch to determine the preferred mode of TRPC6 activation. They also suggest that podocin deficiencies will result in Ca2+ overload in foot processes, as with gain-of-function mutations in the TRPC6 gene. Finally, they suggest that mechanical activation of TRP family channels and the preferred mode of TRP channel activation may depend on whether members of the stomatin/prohibitin family of hairpin loop proteins are present.

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RPC6 Up-Regulation in Ang II-Induced Podocyte Apoptosis Might Result from ERK Activation and NF-κB Translocation

Experimental Biology and Medicine ◽

10.3181/0901-rm-11 ◽

2009 ◽

Vol 234 (9) ◽

pp. 1029-1036 ◽

Cited By ~ 61

Author(s):

Han Zhang ◽

Jie Ding ◽

Qingfeng Fan ◽

Shufang Liu

Keyword(s):

Transient Receptor Potential ◽

Specific Inhibitor ◽

Receptor Potential ◽

Nuclear Factor Κb ◽

Erk Pathway ◽

Ang Ii ◽

Extracellular Signal ◽

Intracellular Ca ◽

Apoptosis Inducer ◽

Transient Receptor

Angiotensin II (Ang II) has been recognized as an apoptosis inducer in podocytes, but the mechanism of apoptosis induced by Ang II is unclear. Transient receptor potential cation channel 6 (TRPC6) is a calcium channel located in podocyte membrane. The present study evaluated the alteration of TRPC6 expression and the Ca2+ influx involved in Ang II-induced podocyte apoptosis. The possible pathways related to TRPC6 in Ang II-induced podocyte apoptosis were also investigated. The apoptosis of mouse podocytes (MPC5) was induced by Ang II. The protein level of TRPC6 was increased markedly in response to Ang II stimulation, and the intracellular Ca2+ concentration was elevated. By transfection with TRPC6 siRNA, Ang II-induced podocyte apoptosis and the transient Ca2+ influx were inhibited. Treated with extracellular signal-regulated kinase (ERK) pathway specific inhibitor U0126 or nuclear factor-κB (NF-κB) pathway specific inhibitor ammonium pyrrolidinedithiocarbamate (PDTC) and Ang II, respectively in podocytes, not only was the TRPC6 up-regulation reduced, but the podocyte apoptosis was also decreased. Moreover, the translocation of NF-κB in nucleus resulted from Ang II was reduced by treatment with U0126. In conclusion, the enhancement expression of TRPC6 as well as the increased Ca2+ influx mediated by TRPC6 channels contributed to the podocyte apoptosis. The activation of ERK pathway and subsequent translocation of NF-κB was possibly necessary for the up-regulation TRPC6 induced by Ang II.

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Gain-of-Function Mutations in the Transient Receptor Potential Channels TRPV1 and TRPA1: How Painful?

Physiological Research ◽

10.33549/physiolres.932658 ◽

2014 ◽

pp. S205-S213 ◽

Cited By ~ 8

Author(s):

S. BOUKALOVA ◽

F. TOUSKA ◽

L. MARSAKOVA ◽

A. HYNKOVA ◽

L. SURA ◽

...

Keyword(s):

Ion Channels ◽

Transient Receptor Potential ◽

Pain Syndrome ◽

Receptor Potential ◽

Transient Receptor Potential Channels ◽

Single Amino Acid ◽

Voltage Sensitivity ◽

Gain Of Function ◽

Potential Channels ◽

Transient Receptor

Gain-of-function (GOF) mutations in ion channels are rare events, which lead to increased agonist sensitivity or altered gating properties, and may render the channel constitutively active. Uncovering and following characterization of such mutants contribute substantially to the understanding of the molecular basis of ion channel functioning. Here we give an overview of some GOF mutants in polymodal ion channels specifically involved in transduction of painful stimuli – TRPV1 and TRPA1, which are scrutinized by scientists due to their important role in development of some pathological pain states. Remarkably, a substitution of single amino acid in the S4-S5 region of TRPA1 (N855S) has been recently associated with familial episodic pain syndrome. This mutation increases chemical sensitivity of TRPA1, but leaves the voltage sensitivity unchanged. On the other hand, mutations in the analogous region of TRPV1 (R557K and G563S) severely affect all aspects of channel activation and lead to spontaneous activity. Comparison of the effects induced by mutations in homologous positions in different TRP receptors (or more generally in other distantly related ion channels) may elucidate the gating mechanisms conserved during evolution.

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Abnormal Somatosensory Behaviors Associated With a Gain-of-Function Mutation in TRPV3 Channels

Frontiers in Molecular Neuroscience ◽

10.3389/fnmol.2021.790435 ◽

2022 ◽

Vol 14 ◽

Author(s):

Mahar Fatima ◽

Hannah Slade ◽

Lorraine Horwitz ◽

Angela Shi ◽

Jingyi Liu ◽

...

Keyword(s):

Transient Receptor Potential ◽

Receptor Potential ◽

Skin Microbiome ◽

Gain Of Function ◽

Noxious Heat ◽

Genetic Mouse Model ◽

Function Point ◽

Specific Pathogen ◽

Cold Acetone ◽

Transient Receptor

Thermosensitive transient receptor potential V3 (TRPV3) is a polymodal receptor implicated in nociceptive, thermoceptive, pruritoceptive, and inflammatory pathways. Reports focused on understanding the role of TRPV3 in thermoception or nociception are not conclusive. Previous studies also show that aberrant hyperactivity of TRPV3 channels results in spontaneous itch and dermatitis-like symptoms, but the resultant behavior is highly dependent on the background of the animal and the skin microbiome. To determine the function of hyperactive TRPV3 channels in somatosensory sensations, we tested different somatosensory behaviors using a genetic mouse model that carries a gain-of-function point mutation G573S in the Trpv3 gene (Trpv3G573S). Here we report that Trpv3G573S mutants show reduced perception of cold, acetone-induced cooling, punctate, and sharp mechanical pain. By contrast, locomotion, noxious heat, touch, and mechanical itch are unaffected in Trpv3G573S mice. We fail to observe any spontaneous itch responses and/or dermatitis in Trpv3G573S mutants under specific pathogen (Staphylococcus aureus)-free conditions. However, we find that the scratching events in response to various pruritogens are dramatically decreased in Trpv3G573S mice in comparison to wild-type littermates. Interestingly, we observe sensory hypoinnervation of the epidermis in Trpv3G573S mutants, which might contribute to the deficits in acute mechanical pain, cool, cold, and itch sensations.

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