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Dexamethasone activates transient receptor potential canonical 4 (TRPC4) channels via Rasd1 small GTPase pathway


Canonical transient receptor potential 4 (TRPC4) channels are calcium-permeable, nonselective cation channels that are widely distributed in mammalian cells. It is generally speculated that TRPC4 channels are activated by Gq/11-PLC pathway or directly activated by Gi/o proteins. Although many mechanistic studies regarding TRPC4 have dealt with heterotrimeric G proteins, here, we first report the functional relationship between TRPC4 and small GTPase, Rasd1. Rasd1 selectively activated TRPC4 channels, and it was the only Ras protein among Ras protein family that can activate TRPC4 channels. For this to occur, it was found that certain population of functional Gαi1 and Gαi3 proteins are essential. Meanwhile, dexamethasone, a synthetic glucocorticoid and anti-inflammatory drug was known to increase messenger RNA (mRNA) level of Rasd1 in pancreatic β-cells. We have found that dexamethasone triggers TRPC4-like cationic current in INS-1 cells via increasing protein expression level of Rasd1. This relationship among dexamethasone, Rasd1, and TRPC4 could suggest a new therapeutic agent for hospitalized diabetes mellitus (DM) patients with prolonged dexamethasone prescription.

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  1. Atwood BK, Lopez J, Wager-Miller J, Mackie K, Straiker A (2011) Expression of G protein-coupled receptors and related proteins in HEK293, AtT20, BV2, and N18 cell lines as reveled by microarray analysis. BMC Genomics 12(14):1474–2164

    Google Scholar 

  2. Barren B, Artemyev NO (2007) Mechanism of dominant negative G-protein α subunits. J Neurosci Res 85:3505–3514

    Article  CAS  PubMed  Google Scholar 

  3. Bezzerides VJ, Ramsey IS, Kotecha S, Greka A, Clapham DE (2004) Rapid vesicular translocation and insertion of TRP channels. Nat Cell Biol 6(8):709–720

    Article  CAS  PubMed  Google Scholar 

  4. Cheng HY, Obrietan K (2006) Dexras1: shaping the responsiveness of the circadian clock. Semin Cell Dev Biol 17(3):345–51

    Article  CAS  PubMed  Google Scholar 

  5. Cismowski MJ, Lanier SM (2005) Activation of heterotrimeric G-proteins independent of a G-protein coupled receptor and the implications for signal processing. Rev Physiol Biochem Pharmacol 155:57–80

    Article  CAS  PubMed  Google Scholar 

  6. Cismoski MJ, Ma C, Ribas C, Xie X, Spruy M, Lizano JS, Lanier SM, Duzie M (2000) Activation of heterotrimeric G-protein signaling by a ras-related protein. J Biol Chem 275:23421–23424

    Article  Google Scholar 

  7. Graham TE, Prossnitz ER, Dorin RI (2002) Dexras1/AGS-1 inhibits signal transduction from the G(i)-coupled formyl receptor to Erk-1/2 MAP kinases. J Biol Chem 277:10876–10882

    Article  CAS  PubMed  Google Scholar 

  8. Heo WD, Tobias M (2003) Switch-of-function mutants based on morphology classification of ras superfamily small GTPases. Cell 113:315–328

    Article  CAS  PubMed  Google Scholar 

  9. Jeon JP, Hong C, Park EJ, Cho NH, Kim IG, Choe H, Muallem S, Kim HJ, So I (2012) Selective Gαi subunits as novel direct activators of transient receptor potential canonical (TRPC)4 and TRPC5 channels. J Biol Chem 287(21):17029–17039

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  10. Jeon JP, Lee KP, Park EJ, Sung TS, Kim BJ, Jeon JH, So I (2008) The specific activator of TRPC4 by Gi protein subtype. Biochem Biophys Res Commun 377(2):538–543

    Article  CAS  PubMed  Google Scholar 

  11. Jeon JP, Roh SE, Wie J, Kim J, Kim H, Lee KP, Yang D, Jeon JH, Cho NH, Kim IG, Kang DE, Kim HJ, So I (2013) Activation of TRPC4β by Gαi subunit increases Ca2+ selectivity and controls neurite morphogenesis in cultured hippocampal neuron. Cell Calcium 54(4):307–319

    Article  CAS  PubMed  Google Scholar 

  12. Kang TM, Kim YC, Sim JH, Rhee JC, Kim SJ, Uhm DY, So I, Kim KW (2001) The properties of carbachol-activated nonselective cation channels at the single channel level in guinea pig gastric myocytes. Jpn J Pharmacol 85(3):291–298

    Article  CAS  PubMed  Google Scholar 

  13. Kemppainen RJ, Behrend EN (1998) Dexamethasone rapidly induces a novel Ras superfamily member-related gene in AtT-20 cells. J Biol Chem 237(6):3129–3131

    Article  Google Scholar 

  14. Kim H, Jeon JP, Hong C, Kim J, Myeong J, Jeon JH, So I (2013) An essential role of PI(4,5)P2 for maintain the activity of the transient receptor potential canonical (TRPC)4β. Pflugers Arch Eur J Physiol 465(7):1011–1021

    Article  CAS  Google Scholar 

  15. Lee YM, Kim BJ, Kim HJ, Yang DK, Zhu MH, Lee KP, So I, Kim KW (2003) TRPC5 as a candidate for the nonselective cation channel activated by muscarinic stimulation in murine stomach. Am J Physiol Gastrointest Liver Physiol 284(4):G604–616

    Article  CAS  PubMed  Google Scholar 

  16. Lellis-Santos C, Sakamoto LH, Bromati CR, Nogueira TC, Leite AR, Yamanaka TS, Kinote A, Anhe GF, Bordin S (2012) The regulation of Rasd1 expression by glucocorticoids and prolactin controls peripartum maternal insulin secretion. Endocrinology 153(8):3668–3678

    Article  CAS  PubMed  Google Scholar 

  17. Montell C (1997) New light on TRP and TRPL. Mol Pharmacol 52(5):755–763

    Article  CAS  PubMed  Google Scholar 

  18. Montell C (2005) Drosophila TRP channels. Pflugres Arch Eur J Physiol 451(1):19–28

    Article  CAS  Google Scholar 

  19. Nilius B, Owasinik G, Voets T, Peters JA (2007) Transient receptor potential cation channels in disease. Physiol Rev 87(1):165–217

    Article  CAS  PubMed  Google Scholar 

  20. Odell AF, Scott JL, Van Helden DF (2005) Epidermal growth factor induces tyrosine phosphorylation, membrane insertion, and activation of transient receptor potential channel 4. J Biol Chem 280(45):37974–37987

    Article  CAS  PubMed  Google Scholar 

  21. Ong SA, Tan JJ, Tew WL, Chen KS (2011) Rasd1 modulates the coactivator function of NonO in the cyclic AMP pathway. PLoS ONE 6(9):e24401

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  22. Otsuguro K, Tang J, Tang Y, Xiao R, Freichel M, Tsvilovskyy V, Ito S, Flockerzi V, Zhu MX, Zholos AV (2008) Isoform-specific inhibition of TRPC4 channel by phosphatidylinositol 4,5-bisphosphate. J Biol Chem 283(15):10026–10036

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  23. Park SH, Ryu SY, Yu WJ, Han YE, Ji YS, Oh K, Sohn JW, Lim A, Jeon JP, Lee H, Lee KH, Lee SH, Berggren PO, Jeon JH, Ho WK (2013) Leptin promotes K(ATP) channel trafficking by AMPK signaling in pancreatic β-cells. Proc Natl Acad Sci 110(31):12673–12678

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  24. Powers AC (2008) Harrison’s principles of internal medicine 17th edn. McGrawHill 338:2275-2304

  25. Ribas C, Takesono A, Sato M, Hildebrandt JD, Lanier SM (2002) Pertussis toxin-insensitive activation of the heterotrimeric G-proteins Gi/Go by the NG108-15 G-protein activator. J Biol Chem 277(52):50223–50225

    Article  CAS  PubMed  Google Scholar 

  26. Sato M, Blumer JB, Simon V, Lanier SM (2006) Accessory proteins for G proteins: partners in signaling. Annu Rev Pharmacol Toxicol 46:157–1587

    Article  Google Scholar 

  27. So I, Kim KW (2003) Nonselective cation channels activated by the stimulation of muscarinic receptors in mammalian gastric smooth muscle. J Smooth Muscle Res 39(6):231–247

    Article  CAS  PubMed  Google Scholar 

  28. Takesono A, Nowak MW, Cismowski M, Duzic E, Lanier SM (2002) Activator of G-protein signaling 1 blocks GIRK channel activation by a G-protein-coupled receptor: apparent disruption of receptor signaling complexes. J Biol Chem 277(16):13827–13830

    Article  CAS  PubMed  Google Scholar 

  29. Tan JJ, Ong SA, Chen KS (2011) Rasd1 interacts with Ear2 (Nr2f6) to regulate renin transcription. BMC Mol Biol 12(4):1471–2199

    Google Scholar 

  30. Thapliyal A, Bannister RA, Hanks C, Adams BA (2008) The monomeric G proteins AGS1 and Rhes selectively influence Galphai-dependent signaling to modulate N-type(CaV2.2) calcium channels. Am J Physiol Cell Physiol 295(5):C1417–1426

    Article  CAS  PubMed  Google Scholar 

  31. Tsai SC, Adamik R, Kanaho Y, Hewlett EL, Moss J (1984) Effects of guanyl nucleotides and rhodopsin on ADP-ribosylation of the inhibitory GTP-binding component of adenylate cyclase by pertussis toxin. J Biol Chem 259(24):15320–15323

    CAS  PubMed  Google Scholar 

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We thank Dr. Won Kyung Ho for providing INS-1 cell line. We thank Dr. M. Schaefer for providing the mouse TRPC4 cDNA, Dr. Y. Mori for providing the mouse TRPC6, and Dr. Shuji Kaneko for providing the human TRPC5-GFP and acknowledge the Missouri S&T cDNA Resource Center ( for providing the M2 receptor cDNAs. We thank Dr. Yong-Sung Juhnn for the human Gαi1 G202T, Gαi2 G203T, and Gαi3 G202T; Dr. Seong-Woo Jeong for all of the Gβγs; and Dr. Won Do Heo for the small G protein. We thank Elsevier for revising the manuscript ( This study was supported by a grant from the Korean Health Technology R&D Project of the Ministry of Health and Welfare of the Republic of Korea (HI13C0104).

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Correspondence to Insuk So.

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Supplementary Figure 1

Specificity of mouse TRPC4β to Rasd1. (A) All panels indicate I-V relationship of currents measured from HEK293 cells expressing mouse TRPC4β-ECFP channel and constitutively active Rasd1 proteins, Rasd1G81A and Rasd1A178V. Enhanced Cyan Fluorescent Protein (pECFP) was expressed as a negative control for Rasd1 proteins since they are tagged with pECFP at their C-terminus (see materials and methods). All Rasd1 proteins were able to activate TRPC4 channels. (B) Summarized current density measured above. Rasd1G81V and Rasd1A178V induced significant TRPC4-like current increase. The comparison between pECFP and Rasd1G81A or Rasd1A178V was carried out with Student’s t-test. Statistical significance was denoted by an asterisk (*) at P < 0.05. (PDF 57 kb)

Supplementary Figure 2

Specificity of Rasd1 to TRPC4β channels among other TRP channels. The effect of Rasd1S33V on other TRPC channels, TRPC4α, TRPC5 or TRPC6. Rasd1S33V could not activate mouse TRPC4α or mouse TRPC6. It rather decreased the activity of human TRPC5 channels. The comparison between TRPC channels and TRPC channels + Rasd1S33V was carried out with Student’s t-test. Statistical significance was denoted by an asterisk (*) at P < 0.05. n.s., not significant. (PDF 18 kb)

Supplementary Figure 3

Time course of M2R-activated TRPC4β channels co-expressed with Rasd1 proteins. All panels indicate time course of currents measured from HEK293 cells expressing mouse TRPC4β channels, human muscarinic acetylcholine receptor type 2 (M2R) and indicated Ras family proteins, Rasd1S33V or Rasd1G31V. 100 μM of extracellular carbachol was applied in order to stimulate muscarinic receptors. (A) Under carbachol stimulation, TRPC4β channel was strongly activated with fast activation. (B) Under carbachol stimulation, TRPC4β channel showed minute activation, hence small inward current when Rasd1S33V was co-expressed. (C) The carbachol-M2R-mediated TRPC4β channel activation was fully recovered when Rasd1G31V, a dominant negative form of Rasd1, was co-expressed instead of Rasd1S33V. Black arrow heads (NT) and red arrow heads (Cs + CCh) indicate the time points where corresponding I-V curves were obtained. (PDF 192 kb)

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Wie, J., Kim, J., Ha, K. et al. Dexamethasone activates transient receptor potential canonical 4 (TRPC4) channels via Rasd1 small GTPase pathway. Pflugers Arch - Eur J Physiol 467, 2081–2091 (2015).

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