Human catestatin enhances migration and proliferation of normal human epidermal keratinocytes

Abstract

Background: Skin-derived antimicrobial peptides, such as human β-defensins and cathelicidins, actively contribute to host defense by inactivating microorganisms. Catestatin, a neuroendocrine peptide that affects human autonomic functions, has recently been detected in keratinocytes upon injury/infection where it inhibits the growth of pathogens. Human catestatin exhibits three single nucleotide polymorphisms: Gly364Ser, Pro370Leu, and Arg374Gln.

Objective: To investigate the effects of human catestatin and its variants on keratinocyte migration and proliferation, and to elucidate the possible signaling mechanisms involved.

Methods: The migration of normal human keratinocytes was analyzed using Boyden microchamber assay and in vitro wound closure assay. Cell proliferation was evaluated by BrdU incorporation, cell count assay and cell cycle analysis. Intracellular Ca(2+) mobilization was measured using a fluorescent calcium assay kit. The phosphorylation of epidermal growth factor receptor (EGFR), Akt, and MAPKs was determined by Western blotting.

Results: Catestatin and its variants dose-dependently enhanced keratinocyte migration and proliferation. Moreover, catestatin peptides increased intracellular Ca(2+) mobilization and induced the phosphorylation of EGFR, Akt, extracellular signal-regulated kinase (ERK), and p38 in keratinocytes. The induction of keratinocyte migration and proliferation by catestatin peptides involved G-proteins, phospholipase C, EGFR, PI3-kinase, ERK, and p38, as evidenced by the specific inhibitory effects of pertussis toxin (G-protein inhibitor), U-73122 (phospholipase C inhibitor), AG1478 (EGFR inhibitor), anti-EGFR antibody, wortmannin (PI3-kinase inhibitor), U0126 (ERK inhibitor), and SB203580 (p38 inhibitor), respectively.

Conclusion: Besides inhibiting the growth of skin pathogens, catestatin peptides may also contribute to cutaneous wound closure by enhancing keratinocyte migration and proliferation at the wound site.