CaMKII (Ca2+/Calmodulin-Dependent Kinase II) in Mitochondria of Smooth Muscle Cells Controls Mitochondrial Mobility, Migration, and Neointima Formation

Arterioscler Thromb Vasc Biol. 2018 Jun;38(6):1333-1345. doi: 10.1161/ATVBAHA.118.310951. Epub 2018 Mar 29.

Abstract

Objective: The main objective of this study is to define the mechanisms by which mitochondria control vascular smooth muscle cell (VSMC) migration and impact neointimal hyperplasia.

Approach and results: The multifunctional CaMKII (Ca2+/calmodulin-dependent kinase II) in the mitochondrial matrix of VSMC drove a feed-forward circuit with the mitochondrial Ca2+ uniporter (MCU) to promote matrix Ca2+ influx. MCU was necessary for the activation of mitochondrial CaMKII (mtCaMKII), whereas mtCaMKII phosphorylated MCU at the regulatory site S92 that promotes Ca2+ entry. mtCaMKII was necessary and sufficient for platelet-derived growth factor-induced mitochondrial Ca2+ uptake. This effect was dependent on MCU. mtCaMKII and MCU inhibition abrogated VSMC migration and mitochondrial translocation to the leading edge. Overexpression of wild-type MCU, but not MCU S92A, mutant in MCU-/- VSMC rescued migration and mitochondrial mobility. Inhibition of microtubule, but not of actin assembly, blocked mitochondrial mobility. The outer mitochondrial membrane GTPase Miro-1 promotes mitochondrial mobility via microtubule transport but arrests it in subcellular domains of high Ca2+ concentrations. In Miro-1-/- VSMC, mitochondrial mobility and VSMC migration were abolished, and overexpression of mtCaMKII or a CaMKII inhibitory peptide in mitochondria (mtCaMKIIN) had no effect. Consistently, inhibition of mtCaMKII increased and prolonged cytosolic Ca2+ transients. mtCaMKII inhibition diminished phosphorylation of focal adhesion kinase and myosin light chain, leading to reduced focal adhesion turnover and cytoskeletal remodeling. In a transgenic model of selective mitochondrial CaMKII inhibition in VSMC, neointimal hyperplasia was significantly reduced after vascular injury.

Conclusions: These findings identify mitochondrial CaMKII as a key regulator of mitochondrial Ca2+ uptake via MCU, thereby controlling mitochondrial translocation and VSMC migration after vascular injury.

Keywords: calcium; calcium-calmodulin-dependent protein kinase type 2; hyperplasia; microtubules; mitochondria; neointima.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Channels / genetics
  • Calcium Channels / metabolism
  • Calcium Signaling
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / genetics
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / metabolism*
  • Carotid Artery Injuries / enzymology*
  • Carotid Artery Injuries / genetics
  • Carotid Artery Injuries / pathology
  • Cell Movement*
  • Cells, Cultured
  • Disease Models, Animal
  • Hyperplasia
  • Male
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Mitochondria, Muscle / enzymology*
  • Mitochondria, Muscle / pathology
  • Muscle, Smooth, Vascular / enzymology*
  • Muscle, Smooth, Vascular / pathology
  • Myocytes, Smooth Muscle / enzymology*
  • Myocytes, Smooth Muscle / pathology
  • Neointima*
  • rho GTP-Binding Proteins / genetics
  • rho GTP-Binding Proteins / metabolism

Substances

  • Calcium Channels
  • Miro-1 protein, mouse
  • mitochondrial calcium uniporter
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • rho GTP-Binding Proteins
  • Calcium