Reactivity of astrocytes to fibroblast growth factor-1 for biogenesis of apolipoprotein E-high density lipoprotein is down-regulated by long-time secondary culture.
We previously showed that astrocytes produce and release fibroblast growth factor-1 (FGF-1) upon 1-month primary and 1-week secondary culture (M/W cells) and stimulate themselves by an autocrine manner to produce apoE-high-density lipoproteins (HDL), closely associated with their generation of apoE-HDL in brain injury. Astrocytes prepared by 1-week primary and 1-month secondary culture (W/M cells), however, expressed FGF-1 as much as M/W cells but produce apoE-HDL much less. The W/M cells conditioned medium in fact contained FGF-1 activity to stimulate astrocytes prepared by 1-week primary and 1-week-secondary culture (W/W cells). FGF-1 did not stimulate W/M cells for apoE-HDL biogenesis while it stimulated W/W cells. Phosphorylation of Akt, ERK and MEK were induced by FGF-1 in W/W cells but not in W/M cells. Finally, fibroblast growth factor receptor-1 in the membrane decreased in W/M cells in comparison to W/W cells. Interestingly, the reactivity of astrocytes to FGF-1 was recovered when W/M cells were transferred to the tertiary culture of 1 week. We concluded that astrocytes decrease their reactivity to FGF-1 for apoE-HDL biogenesis in certain conditions. The findings indicate astrocyte FGF-1 enhances biogenesis of apoE-HDL also by a paracrine mechanism.
Nagayasu
Yuko
Y
Biochemistry, Nagoya City University Graduate School of Medical Sciences, Kawasumi 1, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
Ito
Jin-Ichi
J
Nishida
Tomo
T
Yokoyama
Shinji
S
D000818:Animals; D001057:Apolipoproteins E / Q000096:biosynthesis* / Q000235:genetics; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D015536:Down-Regulation; D016220:Fibroblast Growth Factor 1 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction
D001057:Apolipoproteins E; D017077:Culture Media, Conditioned; D012333:RNA, Messenger; D016220:Fibroblast Growth Factor 1