Regulation of the novel Mg2+ transporter transient receptor potential melastatin 7 (TRPM7) cation channel by bradykinin in vascular smooth muscle cells

Callera, G.E., He, Y., Yogi, A., Montezano, A.C., Paravicini, T., Yao, G. and Touyz, R.M. (2009) Regulation of the novel Mg2+ transporter transient receptor potential melastatin 7 (TRPM7) cation channel by bradykinin in vascular smooth muscle cells. Journal of Hypertension, 27(1), pp. 155-166. (doi: 10.1097/HJH.0b013e3283190582)

Abstract

Background: Transient receptor potential melastatin 7 (TRPM7) channels have been identified in the vasculature. However, their regulation and function remain unclear.<p></p> Methods: Here, we tested the hypothesis that bradykinin and its second messenger cAMP upregulate TRPM7, which stimulates activation of annexin-1 (TRPM7 substrate) and increases transmembrane Mg2+ transport and vascular smooth muscle cell (VSMC) migration. Human and rat VSMCs were studied. TRPM7 phosphorylation was assessed by immunoprecipitation:immunoblotting using antiphospho-serine/threonine and anti-TRPM7 antibodies. [Mg2+]i was measured by mag-fura-2. TRPM7 was downregulated by small interfering RNA and 2-aminoethoxydiphenyl borate. Annexin-1 activity was assessed by cytosol-to-membrane translocation. Cell migration and invasion, functional responses to bradykinin, were assessed in transwell chambers.<p></p> Results: Bradykinin increased expression of TRPM7 and annexin-1. TRPM7 was rapidly (5 min) phosphorylated on serine/threonine but not on tyrosine residues by bradykinin. [Mg2+]i was increased in bradykinin-stimulated cells (0.53 versus 0.68 mmol/l, basal versus bradykinin, P < 0.01). Annexin-1 activation was increased by bradykinin and inhibited by 2-aminoethoxydiphenyl borate. Although Hoe 140 (B2 receptor antagonist), U-73122 (phospholipase C inhibitor), 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (c-Src inhibitor) and chelerythrine (protein kinase C inhibitor) blocked bradykinin actions, dibutyryl-c-AMP was without effect. In small interfering RNA-transfected and in 2-aminoethoxydiphenyl borate-treated cells, bradykinin-induced Mg2+ influx and VSMC migration were reduced.<p></p> Conclusion: Our results demonstrate that bradykinin regulates TRPM7 and its downstream target annexin-1 through phospholipase C-dependent, protein kinase C-dependent and c-Src-dependent and cAMP-independent pathways; effects are mediated through bradykinin type 2 receptor; and bradykinin regulates VSMC [Mg2+]i and migration through TRPM7. These data identify TRPM7/annexin-1/Mg2+ as a novel pathway in bradykinin signaling.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Montezano, Dr Augusto and Touyz, Professor Rhian
• Authors: Callera, G.E., He, Y., Yogi, A., Montezano, A.C., Paravicini, T., Yao, G., and Touyz, R.M.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Journal of Hypertension
• ISSN: 0263-6352
• ISSN (Online): 1473-5598