The Role of Shear-Induced Transforming Growth Factor-β Signaling in the Endothelium

Abstract

Objective Vascular endothelial cells (ECs) are continuously exposed to blood flow that contributes to the maintenance of vessel structure and function; however, the effect of hemodynamic forces on transforming growth factor-β (TGF-β) signaling in the endothelium is poorly described. We examined the potential role of TGF-β signaling in mediating the protective effects of shear stress on ECs. Approach and Results Human umbilical vein endothelial cells (HUVECs) exposed to shear stress were compared to cells grown under static conditions. Signaling through the TGF-β receptor ALK5 was inhibited with SB525334. Cells were examined for morphological changes and harvested for real-time PCR, western blot analysis, apoptosis, proliferation and immunocytochemistry. Shear stress resulted in ALK5-dependent alignment of HUVECs as well as attenuation of apoptosis and proliferation compared to static controls. Shear stress lead to an ALK5-dependent increase in TGF-β3 and Krüppel-like factor 2 (KLF2), phosphorylation of endothelial nitric oxide synthase (eNOS) and NO release. Addition of the NO donor S-nitroso-N-acetylpenicillamine (SNAP) rescued the cells from apoptosis due to ALK5 inhibition under shear stress. Knockdown of TGF-β3, but not TGF-β1, disrupted the HUVEC monolayer and prevented the induction of KLF2 by shear. Conclusions Shear stress of HUVECs induces TGF-β3 signaling and subsequent activation of KLF2 and NO, and represents a novel role for TGF-β3 in the maintenance of HUVEC homeostasis in a hemodynamic environment.

TRPV4-mediated mechanotransduction regulates the metabolic response of chondrocytes to dynamic loading

“…However, unlike the response of ATDC5 chondroprogenitors, we did not concurrently observe transcriptional enhancement of chondrocyte SOX9 with TRPV4 activation, suggesting that fully differentiated articular chondrocytes use an alternate mechanism for COL2α1 enhancement. Transforming growth factor (TGF) signaling plays an important role in cartilage development and homeostasis (53), as well as the response of other cell types to mechanical stimulation (54,55). The mechanoresponsiveness of chondrocyte TGF-β3 gene expression that preceded the regulation of the other genes measured in this study, along with its dependence on TRPV4 activity to mediate this response, represents an intriguing potential mechanism for the biophysical to biochemical transduction of mechanical loading in articular cartilage.…”

Brain Transforming Growth Factor-β Resists Hypertension Via Regulating Microglial Activation

“…Afterwards, there was no difference between these two groups, which was probably due to an incomplete depletion of TGFβ. To further investigate the role of central TGFβ in BP regulation, we ICV delivered a selective TGFβRI kinase inhibitor SB525334 27 prior to hypertension induction. The specificity of SB525334 in abrogating the effect of TGFβ was validated in C8-B4 microglial cell line (Supplemental Figure III).…”

The use of propranolol in the treatment of infantile haemangiomas: an update on potential mechanisms of action

“…Specifically, increased shear stress has been shown to be associated with a significant abrogation of EC apoptosis induced by different stimuli . These lines of evidence indicate that the antiapoptotic effect of shear stress is mediated by multiple signalling molecules, including VEGFR‐2, activin receptor‐like kinase 5, pregnane X receptor, Kruppel‐like factor 2 and phosphoinositide 3‐kinase/protein kinase B . In contrast, a reduction in, or the absence of, shear stress, either due to a severe reduction of blood flow or the local separation of flow streamlines, is associated with EC apoptosis leading to vessel regression .…”