Expression patterns of sarco/endoplasmic reticulum Ca2+-ATPase and inositol 1,4,5-trisphosphate receptor isoforms in vascular endothelial cells

Expression patterns of sarcoplasmic/endoplasmic-reticulum Ca2+-ATPase (SERC A) and inositol 1,4,5-trisphosphate receptor (IP3R) isoforms were studied i n endothelial cells at the mRNA level by ratio RT-PCR technique and subsequ ent restriction-enzyme analysis. Three types of cells have been used in the present study: rat adrenal medulla microvascular endothelial cells (RAMEC) , rat aortic endothelial cells (RAEC), and human umbilical vein endothelial cells (HUVEC). Our data show the presence of multiple SERCA and IP3R isofo rms in each type of endothelial cells. Freshly isolated HUVEC were an excep tion in this respect since they contained only SERCA(3) without SERCA2b mes sengers. The expression patterns changed upon cell proliferation: SERCA3 an d IP3R-1 messengers decreased, while IP3R-3 increased with culturing. Upon cell differentiation, induced by culturing the cells on Matrigel, the expre ssion pattern of the IP3R changed even further in all endothelial cell type s: IP3R-1 was reduced in all three cell kinds, while IP3R-3 raised signific antly in RAEC and RAMEC. In HUVEC the expression of SERCA returned, upon di fferentiation, to the levels observed in the freshly isolated cells. Thus, the plasticity of expression of various SERCA and IP3R isoforms shows that possibly different Ca2+ pools may play distinct roles in cell proliferation and differentiation.