Prelamin A Accelerates Vascular Calcification via Activation of the DNA Damage Response and Senescence Associated Secretory Phenotype in Vascular Smooth Muscle Cells
Rationale: Vascular calcification is prevalent in the ageing population yet little is known of the mechanisms driving age-associated vascular smooth muscle cell (VSMC) phenotypic change.
Objective: To investigate the role of nuclear lamina disruption, a specific hallmark of VSMC ageing, in driving VSMC osteogenic differentiation.
Methods and Results: Prelamin A, the unprocessed form of the nuclear lamina protein Lamin A, accumulated in calcifying human VSMCs in vitro and in vivo and its over-expression promoted VSMC osteogenic differentiation and mineralization. During VSMC ageing in vitro prelamin A accumulation occurred concomitantly with increased p16 expression and osteogenic differentiation and was associated with increased levels of DNA damage. Microarray analysis showed that DNA damage repair pathways were significantly impaired in VSMCs expressing prelamin A and chemical inhibition or siRNA depletion of the DNA damage response (DDR) kinases ATM/ATR effectively blocked VSMC osteogenic differentiation and mineralization. In co-culture experiments, prelamin A expressing VSMCs induced alkaline phosphatase (ALP) activity in mesenchymal progenitor cells and this was abrogated by inhibition of ATM signalling suggesting DNA damage induces the secretion of pro-osteogenic factors by VSMCs. Cytokine array analysis identified a number of ATM-dependent senescence associated secretory phenotype (SASP) factors/cytokines released by prelamin A positive VSMCs including the calcification regulators BMP2, OPG and IL6.
Conclusions: Prelamin A promotes VSMC calcification and ageing by inducing persistent DNA damage signalling which acts upstream of VSMC osteogenic differentiation and the SASP. Agents that target the DDR and/or prelamin A toxicity may be potential therapies for the treatment of vascular calcification.
- Received November 15, 2012.
- Revision received April 5, 2013.
- Accepted April 5, 2013.