The TET2–H19 axis modulates the osteogenic differentiation of smooth muscle cells and atherosclerotic calcification

Atherosclerotic calcification, which is characterized by the osteogenic differentiation of vascular smooth muscle cells (VSMCs), is prevalent in advanced lesions and contributes to increased plaque vulnerability and the likelihood of rupture, but no approved medical therapies are available to effectively prevent this condition. Here, we investigated the effects of ten-eleven translocation-2 (Tet2) deficiency and overexpression on atherosclerotic calcification, as well as the underlying molecular mechanisms. We found that the expression and activity of TET2 were decreased in calcified human coronary arteries, vitamin D3 overload-induced calcified aortas and diet-induced atherosclerotic aortas. The single-cell transcriptomic analysis revealed that the osteochondrogenic cluster was markedly expanded in VSMC-specific Tet2-deficient mice. Atherosclerotic lesions from VSMC-specific Tet2-deficient mice showed significantly increased calcification and deposition of collagen, whereas VSMC-specific Tet2 overexpression ameliorated atherosclerotic calcification. TET2 knockdown induced the H19-mediated and RUNX2 (runt-related transcription factor 2)-dependent osteogenic differentiation of primary human VSMCs via increased trimethylation of histone H3 lysine 4 at the H19 promoter. Treatment with a calpain inhibitor significantly inhibited calpain activity, attenuated high calcium-induced TET2 destabilization and protected against vascular calcification. Restoring TET2 expression may represent an effective strategy to protect against atherosclerotic calcification.