Radiation-induced H2AX phosphorylation and neural precursor apoptosis in the developing brain of mice.
We showed that gamma irradiation of the developing mouse brain with 2 Gy induced a massive apoptosis of neural precursors but not of neurons within 24 h. Successive phosphorylation and dephosphorylation of histone H2AX have been linked to DNA breaks and repair. Similar numbers of nuclear foci of phosphorylated H2AX (gamma-H2AX) were found 1 h postirradiation in neural precursors and in neurons, suggesting that differences in radiosensitivity were not related to variations in the numbers of DNA double-strand breaks induced by radiation. Surviving neural precursors like neurons totally lost gamma-H2AX within 24 h after irradiation, but they had a slower kinetics of loss of gamma-H2AX foci. This suggests that the DNA repair machinery processed damage more slowly in these neural precursors in relation to their greater radiosensitivity. We also found a bright and diffuse gamma-H2AX staining of nuclei of cells at an early stage of apoptosis, whereas cells at later stages of apoptosis were unstained. This was probably related to phosphorylation and subsequent degradation of H2AX in the course of DNA fragmentation during apoptosis. Detection of gamma-H2AX-bright nuclei may thus be a useful marker of neural cells at an early stage of apoptosis.
Nowak
Ewa
E
Laboratoire de RadioPathologie, DRR, CEA-IPSC, 92265 Fontenay-aux-Roses, France.
Etienne
Olivier
O
Millet
Pascal
P
Lages
Céline Silva
CS
Mathieu
Céline
C
Mouthon
Marc-André
MA
Boussin
François D
FD
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002454:Cell Differentiation / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D006657:Histones / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D010766:Phosphorylation / Q000528:radiation effects; D011829:Radiation Dosage; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D013687:Telencephalon / Q000196:embryology* / Q000378:metabolism* / Q000528:radiation effects; D014916:Whole-Body Irradiation
D006657:Histones; C475961:gamma-H2AX protein, mouse