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Cyclic stretch decreases TRPC4 protein and capacitative calcium entry in rat vascular smooth muscle cells

S H Lindsey1, R M Tribe, E Songu-Mize

  • 1Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido Street, P7-1, New Orleans, LA 70112, United States. salindse@wfubmc.edu

Life Sciences
|June 10, 2008
PubMed

Insights

Mechanical stretch reduces TRPC4 protein expression in vascular smooth muscle cells, potentially protecting against excessive calcium influx. TRPC4 levels recover after the stretch stimulus is removed.

Area of Science:

  • Vascular biology
  • Ion channel regulation
  • Cellular mechanics

Background:

  • Vascular smooth muscle cells (VSMCs) are crucial for regulating blood pressure.
  • TRPC channels (Transient Receptor Potential Canonical) play significant roles in VSMC function.
  • Understanding how mechanical forces affect TRPC expression is vital for cardiovascular health.

Purpose of the Study:

  • To investigate the impact of cyclic stretch on TRPC4 and TRPC6 expression in VSMCs.
  • To determine the effects of mechanical stretch on calcium mobilization in these cells.
  • To elucidate the regulatory mechanisms behind stretch-induced changes in TRPC4.

Main Methods:

  • Primary aortic and mesenteric smooth muscle cells were isolated from Sprague-Dawley rats.
  • Cells were subjected to cyclic mechanical stretch for varying durations.
  • TRPC4 and TRPC6 expression levels were assessed via Western blotting.
  • Capacitative calcium entry and agonist-induced calcium influx were measured using calcium imaging techniques.

Main Results:

  • Cyclic stretch significantly decreased TRPC4 protein expression in VSMCs within 5 hours, with levels remaining suppressed for up to 24 hours.
  • TRPC4 expression returned to baseline levels within 2 hours after cessation of the stretch stimulus.
  • Stretch did not alter TRPC6 expression.
  • Capacitative calcium entry was reduced by stretch, while agonist-induced calcium influx increased.
  • TRPC4 mRNA levels were unaffected, suggesting post-transcriptional regulation.
  • TRPC4 downregulation was linked to extracellular calcium levels and potentially the ubiquitin-proteasome pathway.

Conclusions:

  • Cyclic mechanical stretch downregulates TRPC4 protein expression in VSMCs.
  • This downregulation may serve as a protective mechanism against elevated intracellular calcium levels caused by mechanical stress.
  • TRPC4, not TRPC6, is the primary target of mechanical strain in this context, with its regulation involving protein degradation pathways.

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