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:
- x346dh554
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