Abstract
Toll-like receptors (TLRs) recognise pathogen‑associated molecular patterns, which allow the detection of microbial infection by host cells. Bacterial derived toxin lipopolysaccharide activates TLR4 and leads to the activation of the Smad2 transcription factor. The phosphorylation of the Smad2 transcription factor is the result of the activation of the transforming growth factor-β receptor 1 (TGFBR1). Therefore, we sought to investigate LPS via TLR4 mediated Smad2C phosphorylation dependent on the (trans)activation of the TGFBR1. The invitro used human aortic vascular smooth muscle cells (HA-VSMCs) to assess the implications of TLR4 (trans)activation of the TGFBR1 in vascular pathophysiology. We show that LPS mediated Smad2 carboxy-terminal phosphorylation is inhibited in the presence of TGFBR1 inhibitor SB431542 in HA-VSMCs. Treatment with MyD88 and TRIF pathways antagonists does not affect LPS mediated phosphorylation of Smad2C; however, LPS mediated Smad2 phosphorylation was inhibited in the presence of MMP inhibitor, GM6001 and unaffected in the presence of ROCK inhibitor Y27632. LPS via transactivation of the TGFBR1 stimulates PAI-1 mRNA expression. TLRs are first in line to respond to exogenous invading substances and endogenous molecules; our findings characterise a novel signalling pathway in the context of cell biology. Identifying TLR transactivation of the TGFBR1 may provide future insight into the detrimental implications of pathogens in pathophysiology.
Involvement of Transcription Factor PU. 1 in Phenotypic Transformation of Vascular Smooth Muscle Cells to Macrophage-like Cells
