AKAP1 alleviates VSMC phenotypic modulation and neointima formation by inhibiting Drp1-dependent mitochondrial fission
Jingwen Sun, Yuting Shao, Lele Pei, Qingyu Zhu, Xiaoqiang Yu, Wenjuan Yao
Abstract
The roles and mechanisms of A-kinase anchoring protein 1 (AKAP1) in vascular smooth muscle cell (VSMC) phenotypic modulation and neointima formation are currently unknown. AKAP1 is a mitochondrial PKA-anchored protein and maintains mitochondrial homeostasis. This study aimed to investigate how AKAP1/PKA signaling plays a protective role in inhibiting VSMC phenotypic transformation and neointima formation by regulating mitochondrial fission. The results showed that both PDGF-BB treatment and balloon injury reduced the transcription, expression, and mitochondrial anchoring of AKAP1. In vitro , the overexpression of AKAP1 significantly inhibited PDGF-BB mediated VSMC proliferation and migration, whereas AKAP1 knockdown further aggravated VSMC phenotypic transformation. Additionally, in the balloon injury model in vivo , AKAP1 overexpression reduced neointima formation, the muscle fiber area ratio, and rat VSMC proliferation and migration. Furthermore, PDGF-BB and balloon injury inhibited Drp1 phosphorylation at Ser637 and promoted Drp1 activity and mitochondrial midzone fission; AKAP1 overexpression reversed these effects. AKAP1 overexpression also inhibited the distribution of mitochondria at the plasma membrane and the reduction of PKARIIβ expression induced by PDGF-BB, as evidenced by an increase in mitochondria-plasma membrane distance as well as PKARIIβ protein levels. Moreover, the PKA agonist promoted Drp1 phosphorylation (Ser637) and inhibited PDGF-BB-mediated mitochondrial fission, cell proliferation, and migration. The PKA antagonist reversed the increase in Drp1 phosphorylation (Ser637) and the decline in mitochondrial midzone fission and VSMC phenotypic transformation caused by AKAP1 overexpression. The results of this study reveal that AKAP1 protects VSMCs against phenotypic modulation by improving Drp1 phosphorylation at Ser637 through PKA and inhibiting mitochondrial fission, thereby preventing neointima formation. Schematic summary of protective roles of mitochondrial AKAP1 against mitochondrial fission at the midzone through improving Drp1 phosphorylation (Ser637) in VSMC phenotypic modulation and neointima formation. • AKAP1 participates in protecting against neointima formation. • AKAP1 regulates PKA activity through PKARIIβ subunit. • AKAP1/PKA inhibits mitochondrial fission via phosphorylation of Drp1(Ser637). • AKAP1/PKA signaling is a potential novel repressor for treating intimal hyperplasia. • AKAP1 inhibited mitochondrial distribution at the plasma membrane.