Graduation Year
2022
Document Type
Dissertation
Degree
Ph.D.
Degree Name
Doctor of Philosophy (Ph.D.)
Degree Granting Department
Medicine
Major Professor
George E. Davis, M.D., Ph.D.
Committee Member
Jerome Breslin, Ph.D.
Committee Member
Thomas Taylor-Clark, Ph.D.
Committee Member
Ying Yang, Ph.D.
Committee Member
Erick J. Kushner, Ph.D.
Keywords
Hemorrhagic lesion, k-RasV12, Vascular malformation
Abstract
Activated k-Ras mutations play a role in a variety of pathological conditions, such as arteriovenous malformations (AVMs). To study the effect of activated k-Ras mutation on lumen formation, we engineered human ECs to simultaneously express the activated k-Ras (G12V) mutation and compared their ability to form lumens with control ECs. We demonstrated that ECs with k-RasV12 lead to marked stimulation of EC lumen formation due to dramatic increases in intracellular vacuole formation and fusion, signaling changes including accelerated Src kinase activation, and MT1-MMP-dependent lumen expansion, all of which drive the process of lumen formation. The markedly accentuated lumen formation is accompanied by a strong reduction in pericyte recruitment and basement membrane deposition leading to deficient assembly of capillary networks. One of the serious manifestations of AVMs is their tendency to bleed which can cause hemorrhagic lesions such as strokes. We identify a new pathogenic mechanism that predisposes the active k-Ras expressing EC vessels to regress when exposed to the serine proteinase zymogens, plasminogen, or plasma prekallikrein. We demonstrate that active k-Ras expressing ECs strongly induce the levels of MMP-1 proenzyme compared to control ECs, and readily convert this to active MMP-1 through the action of plasmin or plasma kallikrein, which are generated from their respective zymogens. Active MMP-1 markedly destroys collagenous matrices leading to matrix contraction and destruction of the active k-Ras containing EC tubes which is strongly accelerated compared to control ECs. These latter findings represent a novel mechanism by which active k-Ras carrying vascular malformations may breakdown leading to pathologic hemorrhage.
Scholar Commons Citation
Sun, Zheying, "EC expression of activated k-Ras leads to capillary deficiency due to excessive lumen formation, reduced pericyte recruitment, and an increased susceptibility to MMP-1-dependent vascular regression" (2022). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/10419
