HDAC9 Complex Inhibition Improves Smooth Muscle Dependent Arterial Stenosis

Patients with heterozygous missense mutations in the ACTA2 or MYH11 genes are known to exhibit thoracic aortic aneurysm (TAA) and a risk of early onset aortic dissection. However, less common phenotypes involving arterial obstruction are also observed, including coronary and cerebrovascular stenotic disease. Recently an epigenetic complex containing the histone deacetylase HDAC9 and the long noncoding RNA, MALAT1 was implicated in pathologic vascular smooth muscle cell phenotypic changes in aneurysmal disease, however its involvement in stenotic disease has not been explored. Herein we implicate the HDAC9-MALAT1 complex in transcriptional silencing of contractile associated gene products, known to undergo downregulation in stenotic lesions. Furthermore, neointimal formation was inhibited in Hdac9 or Malat1 deficient mice with preservation of contractile protein expression. Pharmacologic targeting of the complex through either MALAT1 antisense oligonucleotides or inhibition of the methyltransferase EZH2 reduced neointimal formation. In conclusion, we report the implication of the HDAC9-MALAT1 complex in stenotic disease and demonstrate that pharmacologic therapy based on epigenetic targets can ameliorate arterial obstruction in an experimental system. Overall design: ChipSep analysis of ACTA2 mutants versus wild type human smooth muscle cells.