title: Pregnenolone sulphate- and cholesterol-regulated TRPM3 channels coupled to vascular smooth muscle secretion and contraction.
abstract: BACKGROUND
  Transient receptor potential melastatin (TRPM)3 is a calcium-permeable ion channel activated by the neurosteroid pregnenolone sulfate and positively coupled to insulin secretion in beta cells. Although vascular TRPM3 mRNA has been reported, there is no knowledge of TRPM3 protein or its regulation and function in the cardiovascular system.
  
  
  OBJECTIVE
  To determine the relevance and regulation of TRPM3 in vascular biology.
  
  
  RESULTS
  TRPM3 expression was detected at mRNA and protein levels in contractile and proliferating vascular smooth muscle cells. Calcium entry evoked by pregnenolone sulfate or sphingosine was suppressed by TRPM3 blocking antibody or knock-down of TRPM3 by RNA interference. Low-level constitutive TRPM3 activity was also detected. In proliferating cells, channel activity was coupled negatively to interleukin-6 secretion via a calcium-dependent mechanism. In freshly isolated aorta, TRPM3 positively modulated contractile responses independently of L-type calcium channels. Concentrations of pregnenolone sulfate required to evoke responses were higher than the known plasma concentrations of the steroids, leading to a screen for other stimulators. beta-Cyclodextrin was one of few stimulators of TRPM3, revealing the channels to be partially suppressed by endogenous cholesterol, the precursor of pregnenolone. Elevation of cholesterol further suppressed channel activity and loading with cholesterol to generate foam cells precluded observation of TRPM3 activity.
  
  
  CONCLUSIONS
  The data suggest functional relevance of TRPM3 in contractile and proliferating phenotypes of vascular smooth muscle cells, significance of constitutive channel activity, regulation by cholesterol, and potential value of pregnenolone sulfate in therapeutic vascular modulation.
authors.affiliation: Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, LS2 9JT, United Kingdom.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Naylor
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Milligan
authors.forename: Fanning
authors.initials: F
authors.lastname: Zeng
authors.forename: Piruthivi
authors.initials: P
authors.lastname: Sukumar
authors.forename: Bing
authors.initials: B
authors.lastname: Hou
authors.forename: Alicia
authors.initials: A
authors.lastname: Sedo
authors.forename: Nadira
authors.initials: N
authors.lastname: Yuldasheva
authors.forename: Yasser
authors.initials: Y
authors.lastname: Majeed
authors.forename: Dhananjay
authors.initials: D
authors.lastname: Beri
authors.forename: Shan
authors.initials: S
authors.lastname: Jiang
authors.forename: Victoria A L
authors.initials: VA
authors.lastname: Seymour
authors.forename: Lynn
authors.initials: L
authors.lastname: McKeown
authors.forename: Bhaskar
authors.initials: B
authors.lastname: Kumar
authors.forename: Christian
authors.initials: C
authors.lastname: Harteneck
authors.forename: David
authors.initials: D
authors.lastname: O'Regan
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Wheatcroft
authors.forename: Mark T
authors.initials: MT
authors.lastname: Kearney
authors.forename: Clare
authors.initials: C
authors.lastname: Jones
authors.forename: Karen E
authors.initials: KE
authors.lastname: Porter
authors.forename: David J
authors.initials: DJ
authors.lastname: Beech
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002784:Cholesterol / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D011284:Pregnenolone / Q000494:pharmacology*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D050053:TRPM Cation Channels; C475667:TRPM3 protein, human; C533868:TRPM3 protein, mouse; C018370:pregnenolone sulfate; D011284:Pregnenolone; D002784:Cholesterol