THE RESPONSE OF HUMAN DERMAL MICROVASCULAR ENDOTHELIAL-CELLS TO HYPOXIA

Dermal microvascular endothelial cells (DMEC) exposed to hypoxic condi tions show a rapid induction of several proteins that do not increase in other cell types placed in a similar environment. These DMEC protei ns differ from the well-characterized stress proteins that have been o bserved in a wide variety of cultured cell types. The DMEC proteins ar e induced rapidly, within 2-4 h, and are expressed transiently. They i nclude a group of acidic proteins (pI similar to 5-5.2) with molecular weights in the range 100 000-120 000 and at least one glycoprotein (p I 5.1, M(r) 57 000) that is probably expressed on the cell surface. In some primary DMEC cell strains, this response is accompanied by a tra nsient overall increase in protein synthesis. The oxygen-regulated pro teins (ORP) that are induced in most other cell types under hypoxic co nditions show little variation in their rate of synthesis in DMEC with in the first 24 h. The response of DMEC differs from that of umbilical vein endothelial cells (UVEC) and from spindle-shaped cells derived f rom DMEC, that show a response to hypoxia that is similar to most othe r cell types. The changes seen in DMEC proteins take place in the same time scale as ischemia-reperfusion injury and may reflect the special ized change of functions of the microvasculature observed under condit ions of hypoxic stress in vivo.