LIM and cysteine-rich domains 1 is required for thrombin-induced smooth muscle cell proliferation and promotes atherogenesis

Abstract

Restenosis arises after vascular injury and is characterized by arterial wall thickening and decreased arterial lumen space. Vascular injury induces the production of thrombin, which in addition to its role in blood clotting, acts as a mitogenic and chemotactic factor. In exploring the molecular mechanisms underlying restenosis, here we identified LIM and cysteinerich domains 1 (LMCD1) as a gene highly responsive to thrombin in human aortic smooth muscle cells (HASMCs). Of note, LMCD1 depletion inhibited proliferation of human but not murine vascular smooth muscle cells. We also found that by physically interacting with E2F transcription factor 1 (E2F1), LMCD1 mediates thrombin-induced expression of the cell division cycle 6 (CDC6) gene in the stimulation of HASMC proliferation. Thrombin-induced LMCD1 and CDC6 expression exhibited a requirement for protease-activated receptor 1 (PAR1)-mediated Gαq/11-dependent activation of phospholipase C β3 (PLCβ3). Moreover, the expression of LMCD1 was highly induced in smooth muscle cells located at human atherosclerotic lesions and correlated with CDC6 expression and that of the proliferation marker Ki67. Furthermore, the LMCD1-and SMCαactin-positive cells had higher cholesterol levels in the atherosclerotic lesions. In conclusion, these findings indicate that by acting as a coactivator with E2F1 in CDC6 expression, LMCD1 stimulates HASMC proliferation and thereby promotes human atherogenesis, suggesting an involvement of LMCD1 in restenosis.Restenosis, characterized by arterial wall thickening and decreased arterial lumen space, occurs as a response to vascular injury (1, 2). Vascular smooth muscle cell (VSMC) migration and proliferation in the tunica intima is the root cause of restenosis (1-3). Vascular injury stimulates coagulation cascade activation and produces substantial amounts of thrombin (4). The thrombus formed due to injury can serve as a reservoir of active thrombin (5). Thrombin, in addition to its vital role in blood clotting, acts as a mitogen and chemotactic factor to a variety of cell types, including peripheral blood monocytes and VSMCs (6-8). In identifying the thrombin-induced genes by microarray analysis, we found that a novel LIM and cysteine-rich domains 1 (LMCD1) gene was induced by thrombin in a sustained manner in human aortic smooth muscle cells (HASMCs). LMCD1, a member of the LIM protein family, contains a novel cysteine-rich domain at the N-terminus, a central PET (Prickle, Espinas and Testin) domain and two LIM domains at the C-terminal region (9). The proteins containing LIM domains are known to have distinct functions in gene expression, cell adhesion, cytoskeleton remodeling, and signal transduction (10). Although the cellular functions of many LIM proteins have been studied (10), there are only a limited number of reports on the biological functions of LMCD1. It was reported that LMCD1 plays a role in the development of cardiac hypertrophy (11). Another study suggests that LMCD1 acts as a transcriptional repressor for GATA6, a zi...

LMCD1 promotes osteogenic differentiation of human bone marrow stem cells by regulating BMP signaling

“…Previous studies have confirmed the function of LMCD1 in cardiac hypertrophy, thrombin formation, and hepatocellular carcinoma migration 29,55,56 . However, the role of LMCD1 in osteogenic differentiation of BMSCs and bone homeostasis has never been reported before.…”

Testicular Lmcd1 regulates phagocytosis by Sertoli cells through modulation of NFAT1/Txlna signaling pathway

“…In favor of this, it has been shown that LMCD1 inhibits DNA binding of transcriptional factor GATA6 and thus restricts its function during lung and heart development (Rath, Wang, Lu, & Morrisey, 2005). Likewise, by acting as a co‐activator with E2F transcription factor 1, LMCD1 stimulates human aortic smooth muscle cell (HASMC) proliferation and thereby promotes human atherogenesis (Janjanam et al, 2018). In this context, a precise balance between interactions with LMCD1 and NFAT1 is indispensable for the regulation of spatial and temporal activity of NFAT1 as well as other key transcriptional factors in phagocytic SCs.…”

“…Northern blot analysis shows that Lmcd1 is highly expressed in cardiac and skeletal muscles. Functionally, LMCD1 regulates cardiac hypertrophy (Bian et al, 2010) and thrombin‐induced smooth muscle cell proliferation (Janjanam et al, 2018) by interacting with different transcription factors. However, the physiological relevance of LMCD1 signaling beyond circulatory and musculoskeletal systems remains largely unknown.…”

LMCD1 antisense RNA 1 is a newly identified long noncoding RNA

“…Oxidative stress directly targets the Lmcd1 transcription [15]. LMCD1 acts as a coactivator for E2F1 in the modulation of thrombin-induced CDC6 expression while promoting HASMC replication [16]. Par1, Gαq/11, PLCβ3, NFATc1, E2F1 and LMCD1 are involved in thrombin-induced IL-33 expression and migration [17].…”