Increased size and cellularity of advanced atherosclerotic lesions in mice with endothelial overexpression of the human TRPC3 channel

Abstract

In previous in vitro studies, we showed that Transient Receptor Potential Canonical 3 (TRPC3), a calcium-permeable, nonselective cation channel endowed with high constitutive function, is an obligatory component of the inflammatory signaling that controls expression of the vascular cell adhesion molecule-1 (VCAM-1) and monocyte adhesion to coronary artery endothelial cells. Also, TRPC3 expression in these cells was found to be up-regulated by proatherogenic factors, which enhanced inflammation and VCAM-1 expression. However, it remained to be determined whether these in vitro findings were of relevance to atherosclerotic lesion development in vivo. To answer this important question in the present work, we generated mice with endothelial-specific overexpression of human TRPC3 in an Apoe knockout background (TgEST3ApoeKO) and examined lesions in the aortic sinus following 10 and 16 wk on a high-fat diet. No significant differences were found in size or complexity of early stage lesions (10 wk). However, advanced plaques (16 wk) from TgEST3ApoeKO mice exhibited a significant increase in size and macrophage content compared with nontransgenic littermate controls. Remarkably, this change was correlated with increased VCAM-1 and phospho-IkBα immunoreactivity along the endothelial lining of lesions from transgenic animals compared with controls. These findings validate the in vivo relevance of previous in vitro findings and represent, to our knowledge, the first in vivo evidence for a proatherogenic role of endothelial TRPC3.TRPC3 channels | atherosclerosis | endothelial inflammation

Pharmacological evidence for a role of the transient receptor potential canonical 3 (TRPC3) channel in endoplasmic reticulum stress-induced apoptosis of human coronary artery endothelial cells

“…Our previous studies demonstrating that in HCAECs TRPC3-mediated constitutive Ca 2+ influx is obligatory within the inflammatory signaling that controls expression of VCAM-1 and monocyte adhesion to these cells (Smedlund et al, 2010; Smedlund and Vazquez, 2008) revealed potential pathophysiological relevance of the constitutive function of this TRPC. The in vivo relevance of these findings was indeed validated by recent studies in Apoe knockout mice with endothelial-specific overexpression of human TRPC3 (Smedlund et al, 2015). In these mice, advanced atherosclerotic lesions in the aortic sinus were of bigger size, increased cellularity and exhibited augmented endothelial inflammation compared to lesions in non-transgenic mice (Smedlund et al, 2015).…”

“…The in vivo relevance of these findings was indeed validated by recent studies in Apoe knockout mice with endothelial-specific overexpression of human TRPC3 (Smedlund et al, 2015). In these mice, advanced atherosclerotic lesions in the aortic sinus were of bigger size, increased cellularity and exhibited augmented endothelial inflammation compared to lesions in non-transgenic mice (Smedlund et al, 2015). …”

“…Altogether, these observations reveal novel roles of TRPC channels in mechanisms of ER stress-induced apoptosis, and are suggestive of a previously unforeseen therapeutic potential of these channel forming proteins. Studies using mouse models of disease in which endothelial expression of TRPC3 is manipulated, as we recently described in (Smedlund et al, 2015), will provide the appropriate context to appreciate the contribution of endothelial TRPC3 to mechanisms of ER stress in an inflammatory setting.…”

On the Roles of the Transient Receptor Potential Canonical 3 (TRPC3) Channel in Endothelium and Macrophages: Implications in Atherosclerosis

“…3.1 above, we discussed the evidence that demonstrated that in HCAECs the endogenous TRPC3 channels mediate constitutive calcium infl ux and are obligatory for proper operation of infl ammatory signaling through the NFkB pathway [ 25 , 27 ]. The in vivo relevance of these fi ndings was validated in recent studies using Apoe knockout mice with endothelial-specifi c overexpression of human TRPC3 [ 62 ]. Whereas early lesions -10 weeks on high fat diet-in the aortic root were not different from control animals, advanced plaques -16 weeks on high fat diet-in the transgenic mice were larger and of increased cellularity compared to non-transgenic mice.…”

“…However, TRPC3 is also expressed in the other two major plaque cell types namely, smooth muscle (SMC) and endothelial (ECs) cells [ 4 , 5 ]. Atherorelevant functions of TRPC3 in SMCs, if any, are not known and recent work from our laboratory shows that in vivo, TRPC3 supports infl ammation in endothelial cells ( [ 62 ] and Sect. 5.2 below).…”