title: Quiescent astroglia in long-term primary cultures re-enter the cell cycle and require a non-sterol isoprenoid in late G1.
abstract: Astroglia proliferate during brain growth, and can divide again later, particularly during astrogliosis. We investigated whether astroglia in primary cultures of newborn rat brain similarly achieve a state of prolonged quiescence which enables re-entry into the cell division cycle. In cultures after 2 months, cell number plateaued and there were sharp decreases in [3H]thymidine incorporation (70 +/- 5 vs 4 +/- 0.5 cpm/micrograms protein/h at 30 and 60 days, respectively) and in percentages of cell nuclei incorporating bromodeoxyuridine (BrDU) (from 46 +/- 6% to less than 1%). Replating at 10(4) cells/cm2 yielded secondary cultures which synthesized DNA actively. Forty-eight hours of serum deprivation at 2-3 days from subculturing, followed by addition of 10% serum (time 0), resulted in a return to quiescence which persisted until 12 h (G0 + G1). By 20 h (S phase), there were abrupt increases in DNA synthesis (5-fold) and in BrDU-labeled nuclei (from 19 +/- 2 to 76 +/- 8%) and the percentage of glial fibrillary acidic protein (GFAP)-positive cells declined to 14 +/- 2%. Three days later, GFAP-positive cells numbered around 80%. Cell cycling after prolonged quiescence, in a manner similar to that in early astroglial cultures, required a non-sterol derivative of mevalonate in late G1. These data confirm that astroglia in primary cultures, like their counterparts in vivo, have a flexible capacity to enter and depart from quiescence, and most importantly, provide a system for examining regulation of this process.
authors.affiliation: Department of Neurology, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14222.
authors.forename: T J
authors.initials: TJ
authors.lastname: Langan
authors.forename: M C
authors.initials: MC
authors.lastname: Slater
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000166:cytology*; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D002784:Cholesterol / Q000032:analysis; D003470:Culture Media; D004261:DNA Replication; D016193:G1 Phase; D005699:Galactosylceramides / Q000032:analysis; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D007700:Kinetics; D008148:Lovastatin / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D051381:Rats; D013261:Sterols / Q000096:biosynthesis; D013997:Time Factors
chemical_list: D003470:Culture Media; D005699:Galactosylceramides; D005904:Glial Fibrillary Acidic Protein; D009419:Nerve Tissue Proteins; D013261:Sterols; D002784:Cholesterol; D008148:Lovastatin