Date of Award

2014

Degree Type

Thesis

Department

Chemistry

First Advisor

Plow, Edward F.

Subject Headings

Endothelial cells, Cells -- Growth, Cytoskeletal proteins, Integrins, Growth factors, integrin kindlin fibronectin laminin extracellular matrix zyxin tubulin actin clathrin cytoskeletal rearrangement hemodynamic shear stress endothelial cell mechanotransduction vinculin cell-cell junction atherosclerosis colocalization

Abstract

Endothelial cells (ECs) are exposed to changes in shear stress under a variety of physiological and pathological circumstances and respond by changing their shape, gene expression and cytoskeletal arrangement. Integrins are central mediators of these mechanotransduction responses of ECs and integrin function is in turn controlled by interaction of their short cytoplasmic tails with cytoplasmic binding partners. Recent studies have demonstrated the importance of the kindlin family members, known cytoplasmic tail binding proteins, as regulators of integrin function. Our lab has previously shown that kindlin-2 (K2) and kindlin-3 (K3) are both expressed and functionally significant for integrin mediated cellular events in ECs. The conversion of shear stress that realigns ECs in the direction of flow differentially affects the distribution of K2 and K3. This observation was made under shear stress rates of 3 or 10 dynes/cm2 in cells adherent to fibronectin. K2 is present in focal adhesion (FA) under static conditions and becomes redistributed into an increase number of FAs with decreased area and length in response to low shear stress. The change in distribution of K2 in response to flow may explain why its colocalization with VE-cadherin was increased in response to flow in a rate dependent manner. K3 changes from its primary and uniform cytosolic distribution to coalesce into discrete punctate patterns. The K3 punctate patterns were assessed for colocalization with clathrin coated vesicles and microtubules, which was significantly increased and decreased, respectively, under low flow. Shear stress induced kindlin-3 punctae formation corresponds to cleavage likely due to shear stress induced calpain activation. Inhibition of calpain prevents the effects of shear stress induced changes in K3 distribution. On ECs adherent to another matrix protein, laminin, kindlin-3 was observed to redistribute into focal adhesions in response to high flow, which is not fully understood. This report confirms that kindlin-2

Download

Included in

Chemistry Commons

COinS