Role of Kindlin and Functional Interplay with RhoE Small GTPase in Keratinocyte Stratification

Abstract

Keratinocyte differentiation and stratification bases epidermal morphogenesis and kept throughout life as tissue homeostasis and architecture is maintained. Yet, a considerable part of the molecular mechanisms that take place during stratification is still unexplored. Here we describe a novel role in integrin activating protein, kindlin, as promising regulator of keratinocyte stratification. The experimental evidence is shown through knockdown and overexpression of kindlin-1 or kindlin-2 and a double knockdown of kindlin-1 and kindlin-2. A time course analysis for quantification of RhoE and E-cadherin expression profile reveals the effect of kindlin-1 or kindlin-2 absences in establishing cellcell contacts and stratification marker of RhoE transient upregulation upon induction of stratification in keratinocytes. We found RhoE transient upregulation is not achieved in the absence of kindlin-2 and a stark increase in stratifying cells is quantified in kindlin-2 overexpressing cells. Meanwhile, significant increase in E-cadherin expression is only achieved in kindlin-1 knockdown cells with significant difference in E-cadherin basal expression between kindlin-1 deficient and kindlin-2 deficient cells. Integrin activity was measured through quantification of adherent cells on collagen type IV coated plate. We discovered a distinct function of kindlin-1 and kindlin-2 in stratification, with kindlin-1 potentially regulating through E-cadherin expression while kindlin-2 via upstream upregulation of atypical small GTPase, RhoE.