| dc.description.abstract | Background: Cardiovascular disease (CVD) is still the leading cause of death
in the developed as well as developing country. Atherosclerosis and
neointima formation considered as chronic inflammatory diseases, in which
many cells including inflammatory smooth muscle cell (iSMC) were involved.
ISMC differentiation from vascular adventitia stem/progenitor cells
(AdSPCs) has been recently recognised as a critical determinant in
cardiovascular diseases. One study have recently reported an important
role for microRNA-214 (miR-214) in mature vascular SMC functions and
injury-induced neointima formation. However, little is known about the
functional involvements of miR-214 in iSMC differentiation from AdSPCs
and its contribution to adverse arterial remodelling.
Purpose: In this PhD study, I aimed to study the functional importance of
miR-214 and its target gene in iSMC differentiation from AdSPCs and
neointima SMC hyperplasia.
Results: miR-214 expression was significantly increased during SMC
differentiation from AdSPCs in response to TGFβ1. miR-214 gain/loss-offunction
assays showed that miR-214 plays an important role in SMC
differentiation from AdSPCs. By co-incubating AdSPCs with TGFβ1 and TNFα,
AdSPCs were induced to differentiate toward iSMCs as evident by a
decreased expression level of SMC-specific genes, but an increased level of
inflammatory genes in iSMCs. Importantly, such phenotype could be
reverted by miR-214 over-expression. I observed that sonic hedgehogglioma-
associated oncogene 1 (Shh-GLI1) signal was closely modulated
during iSMC differentiation, and demonstrated that Suppressor of Fused
(SuFu) is the functional target of miR-214 controlling iSMC generation from
AdSPCs. Further mechanistic studies revealed that increased amount of the
GLI1 protein was translocalized into nuclei in miR-214 over-expressing or
6
SuFu knockdown cells, and the consensus sequence (GACCACCCA) of GLI1
within gene promoters of smooth muscle alpha-actin (SMαA) and serum
response factor (SRF) was required for their regulation by miR-214 and SuFu.
Additionally, Sufu also functions as a positive regulator for inflammatory
gene regulations in iSMCs. In vivo, I demonstrated that locally enforced
expression of miR-214 in the injured vessels significantly reduced SuFu
expression level, iSMC generation, and inhibited neointima SMC
hyperplasia after injury. Importantly, I observed that perivascularly
transplanted AdSPCs significant contribute to neointima SMC hyperplasia
by differentiating to iSMCs, and miR-214 over-expression could reverse
such an effect. Finally, a decreased expression level of miR-214, but
increased expression level of Sufu was observed in diseased human arteries.
Conclusions/Implications: This thesis reports an unexplored role for miR-
214 in iSMC differentiation from AdSPCs and controlling neointima iSMC
hyperplasia. These findings provide new insights into the therapeutic effect
of miR-214 in vascular diseases. | en_US |
