Corticotropin releasing hormone stimulates proliferation of keratinocytes

Corticotropin releasing hormone (CRH) is a potent mediator of stress responses and stress-induced disorders. Consistent with the broad range of roles proposed for CRH, high-affinity binding sites have been found in various peripheral sites. Recently two types of CRH specific receptor have been identified. Expression of CRH receptor 1 (CRH-R1) gene has been detected in human keratinocyte, but the effects of CRH to keratinocytes are still unknown. We tested whether CRH induced keratinocyte proliferation via interaction with CRH R1. Expression of CRH-R1 mRNA in the human keratinocyte and HSC-2, keratinocyte cell line, was analyzed by RT-PCR. The human keratinocyte and HSC-2 were recognized to have CRH-R1 expression ability. CRH signal is transduced into a cAMP-activated metabolic pathway via interaction with CRH-R1. Radioimmunoassay indicated that CRH binds to CRH receptor in HSC-2 cell when activating the metabolic pathway. Using thymidine incorporation assay, CRH had proliferative effect to HSC-2. This study suggests that CRH induces the proliferation of keratinocytes via interation with CRH receptors.