Author ORCID Identifier

0000-0002-1090-2118

Date of Graduation

12-2021

Document Type

Dissertation (PhD)

Program Affiliation

Biochemistry and Molecular Biology

Degree Name

Doctor of Philosophy (PhD)

Advisor/Committee Chair

Jeffrey A Frost

Committee Member

Carmen W Dessauer

Committee Member

Jeffrey Chang

Committee Member

Joya Chandra

Committee Member

Swathi Arur

Abstract

The neuroepithelial cell transforming gene 1 (Net1) is a RhoA guanine nucleotide exchange factor that promotes cancer cell motility and metastasis. Two isoforms of Net1 exist, Net1 and Net1A, both of which are which sequestered in the nucleus in quiescent cells to prevent aberrant RhoA activation. Many cell motility stimuli drive cytosolic relocalization of Net1A, but mechanisms controlling this event are not fully understood. Here we demonstrate that EGF stimulates Src- and Abl1-dependent phosphorylation of Net1A to promote its cytosolic localization. We find that Abl1 efficiently phosphorylates Net1A on Y373, and that phenylalanine substitution of Y373 prevents Net1A cytosolic localization. Aspartate substitution at Y373 is sufficient to promote Net1A cytosolic accumulation, and expression of Net1A Y373D potentiates EGF-stimulated RhoA activation, Myosin Light Chain 2 phosphorylation, and F-actin accumulation. Expression of Net1A Y373D in breast cancer cells significantly increases cell motility and Matrigel invasion. Moreover, Net1A is required for Abl1- stimulated cell motility, which is rescued by expression of Net1A Y373D, but not Net1A Y373F. This work demonstrates a novel mechanism controlling Net1A subcellular localization to regulate RhoA-dependent cell motility and invasion.

Keywords

Net1, Src, Abl1, RhoA, phosphorylation, motility

Available for download on Wednesday, December 07, 2022

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