Antagonism of Angiotensin II AT1 Receptor and Silencing of CD44 Gene Expression Inhibit Cardiac Fibroblast Activation via Modulating TGF-β1/Smad Signaling Pathway ()
ABSTRACT
Angiotensin II (Ang II) is known to elicit cardiac
fibrosis by activating the AT1 receptor and CD44 expression in the in vivo model. However, the cellular/molecular
mechanisms underlying cardiac fibrosis are still not well understood. This
study examines the roles of the AT1 receptor and CD44 gene expression in
collagen synthesis through Ang II stimulated cardiac fibroblasts. Fibroblasts
were isolated from the neonatal rat hearts; the activation of fibroblasts was evaluated using
the assays of cell viability and migration, and silencing of CD44 gene
expression was conducted with small interfering RNA
(siRNA). Results showed that Ang II significantly increases the cell
proliferation and migration in a dose-dependent manner. Upon
activation, the protein levels of TGF-β1,
Smad2, Smad4 and collagen I were significantly increased (all p < 0.05 vs. unstimulated cells), but
these changes were significantly downregulated by the AT1 receptor
blocker, telmisartan (all p < 0.05 vs. Ang II activated cells). Furthermore,
mRNA and protein level of CD44 were upregulated, and there was a linear
correlation between CD44 and TGF-β1
as demonstrated by Pearson correlation analysis (r = 0.955, p < 0.01). Gene
transfection of fibroblasts with Ad-CD44 siRNA, as evidenced by low levels of
CD44 mRNA and protein, significantly reduced the production of collagen I. In
summary, these results indicate that the proliferation, migration and collagen
production from Ang II activated cardiac fibroblasts are potentially mediated
by the AT1 receptor and CD44. Such a signaling mechanism could be crucial for
the production of collagen and the development of tissue fibrosis in the heart.
Share and Cite:
Bai, F. , Yang, G. , Eskew, J. , Wang, N. , Bose, H. and Zhao, Z. (2020) Antagonism of Angiotensin II AT1 Receptor and Silencing of CD44 Gene Expression Inhibit Cardiac Fibroblast Activation via Modulating TGF-
β1/Smad Signaling Pathway.
Advances in Bioscience and Biotechnology,
11, 123-139. doi:
10.4236/abb.2020.114010.
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