Lipoproteins induce expression of the early growth response gene-1 in vascular smooth muscle cells from rat.
Recently, we reported that low-density lipoprotein (LDL) induces in vascular smooth muscle cells (VSMCs) intracellular effects such as an elevation of intracellular free Ca2+ concentration ([Ca2+]i) and intracellular pH (pHi). The early growth response gene-1 (Egr-1) has been identified as a transcription factor belonging to a class of immediate-early genes expressed upon growth, and/or differentiation signals in a large variety of cells and species. Here we show that LDL induces a dose-dependent expression of the Egr-1 mRNA with a maximum at 30 min. Experiments in the presence of the dihydropyridine calcium blocker isradipine suggest that the lipoprotein-induced Egr-1 mRNA induction occurs via a Ca2+ dependent pathway. To demonstrate whether these intracellular responses are only specific to LDL we examined the effects of high- and very low density lipoprotein (HDL and VLDL) on [Ca2+]i and expression of Egr-1 mRNA. The present results show that all lipoproteins induce expression of Egr-1 mRNA and elevation in [Ca2+]i in VSMCs.
Sachinidis
A
A
Medizinische Universitäts-Poliklinik, Bonn, Germany.
Ko
Y
Y
Wieczorek
A
A
Weisser
B
B
Locher
R
R
Vetter
W
W
Vetter
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D051766:Early Growth Response Protein 1; D005260:Female; D015870:Gene Expression; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017874:Immediate-Early Proteins; D017275:Isradipine / Q000494:pharmacology; D008074:Lipoproteins / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D051381:Rats; D011921:Rats, Inbred WKY; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D008074:Lipoproteins; D012333:RNA, Messenger; D014157:Transcription Factors; D002118:Calcium; D017275:Isradipine