Protein kinase C isoenzymes differentially regulate the differentiation‐dependent expression of adhesion molecules in human epidermal keratinocytes

Abstract

Epidermal expression of adhesion molecules such as desmogleins (Dsg) and cadherins is strongly affected by the differentiation status of keratinocytes. We have previously shown that certain protein kinase C (PKC) isoforms differentially alter the growth and differentiation of human epidermal HaCaT keratinocytes. In this paper, using recombinant overexpression and RNA interference, we define the specific roles of the different PKC isoenzymes in modulation of expression of adhesion molecules in HaCaT keratinocytes. The level of Dsg1, a marker of differentiating keratinocytes, was antagonistically regulated by two Ca-independent 'novel' nPKC isoforms; i.e. it increased by the differentiation-promoting nPKCdelta and decreased by the growth-promoting nPKCepsilon. The expression of Dsg3 (highly expressed in proliferating epidermal layers) was conversely regulated by these isoenzymes, and was also inhibited by the differentiation inducer Ca-dependent 'conventional' cPKCalpha. Finally, the expression of P-cadherin (a marker of proliferating keratinocytes) was regulated by all of the examined PKCs, also in an antagonistic manner (inhibited by cPKCalpha/nPKCdelta and stimulated by cPKCbeta/nPKCepsilon). Collectively, the presented results strongly argue for the marked, differential, and in some instances antagonistic roles of individual Ca-dependent and Ca-independent PKC isoforms in the regulation of expression of adhesion molecules of desmosomes and adherent junctions in human epidermal keratinocytes.

Desmosomes: Regulators of Cellular Signaling and Adhesion in Epidermal Health and Disease

“…It has long been known that PKC signaling regulates expression of desmosomal cadherins in keratinocytes (Denning et al 1998). Suppression of PKC-a or PKC-d isoforms increases Dsg3 expression, whereas suppression of PKC-d and PKC-1 isoforms either decreases or increases Dsg1 levels, respectively (Szegedi et al 2009 (Roemer 2012) and p63 has been shown by chromatin immunoprecipitation (ChIP) to bind and activate Dsg1, Dsc3, and Dp promoters (Ferone et al 2013;Johnson et al 2014). Rho-mediated changes in the actin cytoskeleton lead to changes in Srf-dependent transcription (Miralles et al 2003) and Srf controls the expression of Pkp2 and Dsg1, which in turn drives a program of terminal differentiation (Leitner et al 2011;Dubash et al 2013), The Wnt-regulated TCF/Lef transcription complex has been implicated in regulation of Dsg4, Dsc2, Dsc3, and Pg expression but direct binding of these transcription factors to desmosomal component promoters has only been shown in a few instances (Table 1) (Bazzi et al 2009;Bailey et al 2012;Tokonzaba et al 2013).…”

Protein Kinase C (PKC) δ Suppresses Keratinocyte Proliferation by Increasing p21Cip1 Level by a KLF4 Transcription Factor-dependent Mechanism

“…Among these, PKC␦ is present in all epidermal layers (12,20). A major role has been proposed for PKC␦ in driving keratinocyte differentiation (15,22,23,23,24,31,48). We have extensively studied the mechanism of PKC␦ regulation of differentiation using involucrin as a target (28).…”

Endocannabinoids Modulate Human Epidermal Keratinocyte Proliferation and Survival via the Sequential Engagement of Cannabinoid Receptor-1 and Transient Receptor Potential Vanilloid-1

“…Human immortalized HaCaT KCs were cultured in DMEM (Sigma-Aldrich) supplemented with 10% fetal calf serum, 2 mM L-glutamine, and antibiotics (all from Invitrogen; Bodó et al, 2005;Gö nczi et al, 2008;Kiss et al, 2008;Szegedi et al, 2009).…”