HUMAN KERATINOCYTES EXPRESS THE 3 MAJOR SPLICE FORMS OF VASCULAR ENDOTHELIAL GROWTH-FACTOR

Vascular endothelial growth factor is a powerful mitogen for endotheli al cells, recently reported to be produced by keratinocytes. In the pr esent work, we examined human keratinocytes in primary culture for the splice variants of vascular endothelial growth factor, In situ hybrid ization revealed that 100% of cultured human keratinocytes expressed m RNA for this cytokine, and analysis by reverse transcriptase-polymeras e chain reaction indicated that three species of mRNA were produced. S outhern hybridization and size calculations of PCR products revealed m RNA species corresponding to 121, 165, and 189 amino-acid forms of thi s cytokine, Using a rabbit anti-vascular endothelial growth factor ant iserum, we radioimmunoprecipitated two molecular weight forms (approxi mately 45 and 58 kDa, non-reducing conditions) from keratinocyte cultu re supernatants, Under reducing conditions, three bands of approximate ly 15, 20, and 24 kDa appeared, corresponding with the predominant for ms of vascular endothelial growth factor described. We propose that se cretion of vascular endothelial growth factor by human keratinocytes i n vivo sustains angiogenesis during physiologic tissue repair and in p athologic states accompanied by neovascularization.