Investigation into the Role of Smooth Muscle Notch in Atherosclerosis.
Davis-Knowlton, Jessica.
2019
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Vascular occlusive diseases underlie ischemic heart disease
and stroke, the leading causes of death worldwide. We are interested in
vascular smooth muscle cells (SMC) during atherogenesis, as they contribute
to plaque formation and may determine susceptibility to rupture. Notch
signaling is implicated in vascular disease progression, and we previously
identified a Notch receptor-specific ... read moreregulatory role in SMC proliferation
and contractile phenotype. We hypothesize that Notch signaling within
vascular SMC can regulate plaque morphology. Resected tissue from carotid
and femoral endarterectomies were compared with carotid arteries from
healthy donors. Notch2 and Notch3 within medial and plaque SMC were analyzed
by immunostaining and immunoblot. To better define the protein signature of
diseased SMC, we utilized proteomics to compare normal carotid artery SMC
with endarterectomy-derived SMC. Similarities in protein profile and
differentiation markers validated the SMC identity of our explants and we
identified a subset of differentially expressed proteins. Notch activation
assays of healthy or diseased SMC revealed that in populations that
displayed significant growth, Jagged1 signaling through Notch2 suppressed
proliferation, while cultures with low growth potential were non-responsive.
In addition, Jagged1 did not promote contractile smooth muscle actin nor
have a significant effect on the differentiated phenotype. Thus, SMC derived
from atherosclerotic lesions show distinct proteomic profiles and have
altered Notch signaling in response to Jagged1, compared with normal SMC. To
study Notch2 in atherogenesis in vivo, we developed an atherosclerotic mouse
model that was globally null for apolipoprotein E and Notch2-null in SMC. In
this model floxed Notch2 was paired with inducible smooth muscle-myosin
heavy chain Cre driver line and western diet was used to accelerate
atherogenesis. We validated genomic recombination in our model by PCR and
qPCR and observed a 90% genomic deletion efficiency with no detectable
Notch2 protein in SMC. Apolipoprotein E-null mice experienced plaque burden
and composition that were not different with loss of SMC-Notch2 in aorta or
brachiocephalic artery, while at the aortic root loss of SMC-Notch2 produced
larger, more necrotic plaque. We also ran a pilot study of gain of function
Proprotein convertase subtilisin/kexin type9 induced atherogenesis to
validate this adeno associated virus mediated model of atherosclerosis for
future studies. We focused on plaque burden and composition at the aortic
root and found consistent lesion size, collagen content, and lipid
content.
Thesis (Ph.D.)--Tufts University, 2019.
Submitted to the Dept. of Cell, Molecular & Developmental Biology.
Advisor: Lucy Liaw.
Committee: John Castellot, Calvin Vary, Iris Jaffe, and Aaron Proweller.
Keyword: Molecular biology.read less - ID:
- xd07h7029
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