Prelamin A Accumulation Attenuates Rac1 Activity and Increases the Intrinsic Migrational Persistence of Aged Vascular Smooth Muscle Cells

Abstract

Vascular smooth muscle cell (VSMC) motility is essential during both physiological and pathological vessel remodeling. Although ageing has emerged as a major risk factor in the development of cardiovascular disease, our understanding of the impact of ageing on VSMC motility remains limited. Prelamin A accumulation is known to drive VSMC ageing and we show that presenescent VSMCs, that have accumulated prelamin A, display increased focal adhesion dynamics, augmented migrational velocity/persistence and attenuated Rac1 activity. Importantly, prelamin A accumulation in proliferative VSMCs, induced by depletion of the prelamin A processing enzyme FACE1, recapitulated the focal adhesion, migrational persistence and Rac1 phenotypes observed in presenescent VSMCs. Moreover, lamin A/C-depleted VSMCs also display reduced Rac1 activity, suggesting that prelamin A influences Rac1 activity by interfering with lamin A/C function at the nuclear envelope. Taken together, these data demonstrate that lamin A/C maintains Rac1 activity in VSMCs and prelamin A disrupts lamin A/C function to reduce Rac1 activity and induce migrational persistence during VSMC ageing.

SUN1/2 Are Essential for RhoA/ROCK-Regulated Actomyosin Activity in Isolated Vascular Smooth Muscle Cells

“…The LINC complex has emerged as a regulator of cytoskeletal organisation and SUN2 is essential for the mechanical integrity of intercellular adhesions suggesting that mechanical feedback exists between the NE and cell-cell contacts [17]. Feedback also exists between the NE and matrix adhesions and disruption of lamins A/C function or overexpression of the dominant negative nesprin KASH-domain triggers focal adhesion reorganisation and changes in cell motility [18][19][20]. The nature of this feedback remains unknown, however, lamin A/C and SUN2 have recently been demonstrated to regulate Rac1 and RhoA activity, respectively [20,21].…”

“…Feedback also exists between the NE and matrix adhesions and disruption of lamins A/C function or overexpression of the dominant negative nesprin KASH-domain triggers focal adhesion reorganisation and changes in cell motility [18][19][20]. The nature of this feedback remains unknown, however, lamin A/C and SUN2 have recently been demonstrated to regulate Rac1 and RhoA activity, respectively [20,21]. Although in some contexts LINC complex components are partially redundant, several lines of data suggest that the LINC complex is tailored for cell-type-specific functions.…”

A model for estimating traction force magnitude reveals differential regulation of actomyosin activity and matrix adhesion number in response to smooth muscle cell spreading

“…Cells were cultured on hydrogels, fixed in paraformaldehyde and processed as described previously (28). Invitrogen anti-mouse Alexa fluor 568 (A11031) and anti-rabbit Alexa fluor 488 (A11034) were used as IF secondary antibodies.…”

“…All images were captured at 20x magnification using a Leica SP2 laser scanning confocal microscope. Cell area and aspect ratio was measured using the ImageJ open source analysis software (28). pMLC mean intensity and total intensity were measured using the ROI function in ImageJ.…”

“…pMLC mean intensity and total intensity were measured using the ROI function in ImageJ. Focal adhesion number and size were measured in ImageJ, as described previously (28).…”