Non-lethal active caspase-3 expression in Bergmann glia of postnatal rat cerebellum.
Caspase-3, an apoptotic executor, has been shown in recent years to mediate non-lethal events like cellular proliferation and differentiation, primarily in studies related to non-neural tissue. In central nervous system development, the role of active caspase-3 is still unclear. We provide the first evidence for a potential new role of active (cleaved) caspase-3 in promoting differentiation of Bergmann glia. This study was predicated on the hypothesis that active caspase-3 is important for the differentiation of glia. We addressed the hypothesis through the following specific aims: (1) to establish the expression of active caspase-3 in glia; (2) to determine the developmental phenotype of the active caspase-3-expressing glia; and (3) to confirm that active caspase-3 expression is not mediating an apoptotic event. Through a temporal investigation from postnatal day 8 to 21, we observed that Bergmann glia express active caspase-3 without compromising their survival. Potential apoptotic fate of active caspase-3-positive Bergmann glia were ruled out based on immunohistochemical exclusion of phosphatidylserine exposure (Annexin V), DNA fragmentation (TUNEL), and DNA compaction (TOPRO-3). More than 90% of the active caspase-3-positive cells lacked colabeling for one of the apoptotic markers. Correlative studies using a proliferation marker Ki67 and a differentiation marker brain lipid-binding protein suggest that the expression of active caspase-3 was mostly associated with differentiating rather than proliferating Bergmann glia at all ages. Thus, this study supports the hypothesis that active caspase-3 may be regulating both differentiation of Bergmann glia by allowing the cells to exit the cell cycle and their morphogenesis.
Oomman
Sowmini
S
Department of Physiology, Texas Tech University Health Sciences Center, Room 5A163, Lubbock, TX 79430, USA.
Strahlendorf
Howard
H
Finckbone
VelvetLee
V
Strahlendorf
Jean
J
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D064026:Calbindins; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002452:Cell Count / Q000379:methods; D002531:Cerebellum / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry / Q000379:methods; D020287:In Situ Nick-End Labeling / Q000379:methods; D019394:Ki-67 Antigen / Q000378:metabolism; D009414:Nerve Growth Factors / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009457:Neuroglia / Q000201:enzymology*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D011804:Quinolines; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000378:metabolism; D018709:Statistics, Nonparametric; D019311:Staurosporine / Q000009:adverse effects; D014404:Tubulin / Q000378:metabolism
D017304:Annexin A5; D064026:Calbindins; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D019394:Ki-67 Antigen; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D011804:Quinolines; D064030:S100 Calcium Binding Protein G; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D014404:Tubulin; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D010751:Phosphopyruvate Hydratase; D019311:Staurosporine