Alcohol exposure alters cell cycle and apoptotic events during early neurulation.
BACKGROUND
Fetal alcohol exposure causes growth deficits, microencephaly, and neurological abnormalities. Although the effects of alcohol on developmental delay and growth-related deficits have been hypothesized, little is understood about how alcohol alters, in particular, the cyclin pathway within the cell cycle, which is critical to proliferation and apoptotic control. In this study, we examined cell cycle proteins pertinent to the G1-S phase transition and apoptosis, to determine if cell cycle misregulation can be attributed to apoptotic induction and growth defects.


METHODS
We examined cell cycle regulation during G1 and S-phase, and DNA fragmentation damage, using E14 dorsal root ganglia neural stem cells (DRG-NC), and cultured mouse embryos exposed to 200 and 400 mg/dl ethanol.


RESULTS
Alcohol-exposed DRG-NC demonstrated a dose-dependent increase in cells expressing increased cyclin D1 protein, and increased DNA fragmentation. Western blot analysis, using embryos, demonstrated an overexpression of cyclin D1, D2, and E2F1, key G1 to S-phase cell cycle regulatory components, and increases in p53, linking the cell cycle and apoptotic pathways. Bromodeoxyuridine incorporation indicated reduced DNA synthesis and growth in several embryonic regions. Propidium iodide staining demonstrated decreases in DNA content and increases in DNA fragmentation in several embryonic tissues.


CONCLUSIONS
This study indicated that retarded growth of DRG-NC and embryos, induced by alcohol, is associated with altered expression of cell cycle and apoptotic proteins and concurrent inhibition of proliferation and increased DNA fragmentation. We suggest that alcohol induces an increase in cyclin D1 expression, premature S-phase entry, and disjointed DNA synthesis with increased apoptosis.
Anthony
Bruce
B
Department of Anatomy, Indiana University School of Medicine, Indiana University-Purdue University, 635 Barnhill Drive, Indianapolis, IN 46202, USA.
Zhou
Feng C
FC
Ogawa
Tetsuo
T
Goodlett
Charles R
CR
Ruiz
Joseph
J
D000428:Alcohol Drinking / Q000009:adverse effects / Q000473:pathology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002453:Cell Cycle / Q000187:drug effects* / Q000502:physiology; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D000431:Ethanol / Q000008:administration & dosage* / Q000633:toxicity; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D054261:Neurulation / Q000187:drug effects* / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D018797:Cell Cycle Proteins; D000431:Ethanol