CaMKII is Necessary for Proliferation and Migration of Pulmonary Arterial Smooth Muscle Cells

Abstract

ObjectiveCa2+/calmodulin‐dependent protein kinase II (CaMKII) is a calcium‐ and oxidation‐activated serine/threonine kinase, with four known isoforms. CaMKII has been shown to be necessary for remodeling involving smooth muscle cell proliferation and migration in response to injury in the systemic vasculature. However, the role of CaMKII in pulmonary arterial smooth muscle cell (PASMC) function remains unknown.MethodsPASMCs were isolated from male Wistar rats and expanded in culture. In cell lysates, mRNA expression of CaMKII isoforms was measured by real‐time quantitative reverse transcription PCR; protein expression was assessed via immunoblot. PASMC proliferation was measured via BrdU incorporation. PASMC migration was assessed by the Transwell assay. PASMCs were treated with 10 μM KN‐93 in vitro to inhibit CaMKII or with either vehicle or 10 μM KN‐92 (an inactive analog of KN‐93) for control experiments. To deplete CaMKIIδ protein, PASMCs were treated with 100nM siRNA targeted to CaMKIIδ while PASMCs treated with scrambled siRNA were used for control experiments.ResultsThe CaMKIIδ and CaMKIIγ isoforms showed mRNA and protein expression in rat PASMCs. Both proliferation and migration of rat PASMCs were inhibited by pharmacologic inhibition of CaMKII using KN‐93, but were not inhibited by the inactive analog KN‐92. siRNA‐mediated knockdown of CaMKIIδ resulted in reduction of CaMKIIδ protein expression but did not have an effect on either PASMC proliferation or migration.ConclusionsCaMKII activity is necessary for PASMC proliferation and migration. As the CaMKIIδ isoform is not required for these functions, future work will examine the role of the CaMKIIγ isoform.Support or Funding InformationFunding SourcesNIH K08HL133475 & Pulmonary Hypertension Association K08 Supplement