Regulation of vascular smooth muscle growth by cyclic nucleotides and cGMP-dependent protein kinase

The aim of this work was to elucidate the effect of cyclic nucleotide signaling on the growth of vascular smooth muscle cells (VSMCs). In particular, the role of cGKI in VSMC growth was analysed in primary and subcultured VSMCs derived from wild-type and cGKI-deficient mice. In primary VSMCs, activation of cGMP/cGKI signaling led to a strong increase in growth. In contrast, in repeatedly passaged VSMCs derived from mouse, rat and human, cGMP/cGKI had either no effect on growth or had a weak growth suppressing effect. Thus, cGKI signaling differs in primary vs. subcultured VSMCs. The further analysis of proliferation, apoptosis, cytoskeletal dynamics, and various signaling pathways indicated that an increase in integrin-mediated cell adhesion is the major mechanism for cGKI-mediated growth in primary VSMCs. Thereby, cGMP/cGKI signaling in primary VSMCs might inhibit anoikis, the programmed cell death induced by the loss of cell/matrix interactions.