Abstract：OBJECTIVE: To explore the role and mechanisms of FOXO3a nuclear translocation in neuronal apoptosis after hypoxia-ischemia (HI). METHODS: One hundred and sixty 10-day-old Sprague-Dawly rats were randomly divided into two groups: HI and sham-operated. The right common carotid artery was ligated followed by hypoxia exposure for 2.5 hours in the HI group. The sham-operated group rats were not subjected to carotid artery ligation or hypoxia treatment. Rat cerebral cortex was collected at 0.5, 2, 4, 8 and 24 hours after hypoxia. Western blot was used to detect expression of total FOXO3a protein, pnuclear and cytoplasmic FOXO3a and Bim. TUNEL staining was used to detect apoptotic cells. RESULTS: The nuclear protein of FOXO3a obviously increased from 0.5 to 24 hours after HI in a time-dependent manner compared with the sham-operated group (P<0.01). On the contrary, cytoplasmic protein evidently decreased from 0.5 to 24 hours in the HI group compared with the sham-operated group (P<0.01). Bim protein increased from 0.5 hour, peaked at 2 hours, started to decline at 4 hours (P<0.01), and returned to baseline level at 8 and 24 hours after HI in the HI group compared with the sham-operated group. TUNEL positive cells started to express at 4 hours, and peaked at 24 hours after HI (P<0.01). However, TUNEL positive cells were rarely found in the sham-operated group. CONCLUSIONS: HI induces FOXO3a translocation from cytoplasm to nucleus, and enhances protein expression of its target gene Bim in the neonatal rat brain. The upregulation of Bim expression might be related to neuronal apoptosis
LI De-Yuan,QU Yi,LI Jin-Hui et al. Role of the FOXO3a transcription factor in neuronal apoptosis in neonatal rats with hypoxic-ischemic brain damage[J]. CJCP, 2013, 15(11): 1023-1027.
Putcha GV, Moulder KL, Golden JP, Bouillet P, Adams JA, Strasser A, et al. Induction of BIM, a proapoptotic BH3-only BCL-2 family member, is critical for neuronal apoptosis[J]. Neuron, 2001, 29(3): 615-628.
[1]
Nakamura N, Ramaswamy S, Vazquez F, Signoretti S, Loda M, Sellers WR. Forkhead transcription factors are critical effectors of cell death and cell cycle arrest downstream of PTEN[J]. Mol Cell Biol, 2006, 20(23): 8969-8982.
[18]
Xie B, Wang C, Zheng Z, Song B, Ma C, Thiel G, et al. Egr-1 transactivates Bim gene expression to promote neuronal apoptosis[J]. J Neurosci, 2011, 31(13): 5032-5044.
[2]
Rice JE 3rd, Vannucci RC, Brierley JB. The influence of immaturity on hypoxic-ischemic brain damage in the rat[J]. Ann Neurol, 1981, 9(2): 131-141.
[19]
Shibata M, Hattori H, Sasaki T, Gotoh J, Hamada J, Fukuuchi Y. Temporal profiles of the subcellular localization of Bim, a BH3-only protein, during middle cerebral artery occlusion in mice[J]. J Cereb Blood Flow Metab, 2002, 22(7): 810-820.
[3]
Xiong T, Tang J, Zhao J, Chen H, Zhao F, Li J, et al. Involvement of the Akt/GSK-3β/CRMP-2 pathway in axonal injury after hypoxic-ischemic brain damage in neonatal rat[J]. Neuroscience, 2012, 216(2): 123-132.
[4]
Sugawara T, Fujimura M, Noshita N, Kim GW, Saito A, Hayashi T. Neuronal death/survival signaling pathways in cerebral ischemia[J]. NeuroRx, 2004, 1(1): 17-25.
Lam EW, Francis RE, Petkovic M. FOXO transcription factors: key regulators of cell fate[J]. Biochem Soc Trans, 2006, 34(Pt 5): 722-726.
[7]
Santo EE, Stroeken P, Sluis PV, Koster J, Versteeg R, Westerhout EM. FOXO3a is a major target of inactivation by PI3K/AKT signaling in aggressive neuroblastoma[J]. Cancer Res, 2013, 73(7): 2189-2198.
[8]
Furukawa-Hibi Y, Kobayashi Y, Chen C, Motoyama N. FOXO transcription factors in cell-cycle regulation and the response to oxidative stress[J]. Antioxid Redox Signal, 2005, 7(5-6): 752-760.
Monsalve M, Olmos Y. The complex biology of FOXO[J]. Curr Drug Targets, 2011, 12(9): 1322.
[11]
Eijkelenboom A, Burgering BM. FOXOs: signalling integrators for homeostasis maintenance[J]. Nat Rev Mol Cell Biol, 2013, 14(2): 83-97.
[12]
Hagberg H, Ichord R, Palmer C, Yager JY, Vannucci SJ. Animal models of developmental brain injury: Relevance to human disease. A summary of the panel discussion from the Third Hershey Conference on Developmental Cerebral Blood Flow and Metabolism[J]. Dev Neurosci, 2002, 24(5): 364-366.
[13]
Lehtinen MK, Yuan Z, Boag PR, Yang Y, Villen J, Becker EB. A conserved MST-FOXO signaling pathway mediates oxidative-stress responses and extends life span[J]. Cell, 2006, 125(5): 987-1001.
[14]
Gilley J, Coffer PJ, Ham J. FOXO transcription factors directly activate bim gene expression and promote apoptosis in sympathetic neurons[J]. J Cell Biol, 2003, 162(4): 613-622.
[15]
Meller R, Cameron JA, Torrey DJ, Clayton CE, Ordonez AN, Henshall DC, et al. Rapid degradation of Bim by the ubiquitin-proteasome pathway mediates short-term ischemic tolerance in cultured neurons[J]. J Biol Chem, 2006, 281(11): 7429-7436.
[16]
Meller R. The role of the ubiquitin proteasome system in ischemia and ischemic tolerance[J]. Neuroscientist, 2009, 15(3): 243-260.
[17]
Putcha GV, Moulder KL, Golden JP, Bouillet P, Adams JA, Strasser A, et al. Induction of BIM, a proapoptotic BH3-only BCL-2 family member, is critical for neuronal apoptosis[J]. Neuron, 2001, 29(3): 615-628.
[18]
Xie B, Wang C, Zheng Z, Song B, Ma C, Thiel G, et al. Egr-1 transactivates Bim gene expression to promote neuronal apoptosis[J]. J Neurosci, 2011, 31(13): 5032-5044.
[19]
Shibata M, Hattori H, Sasaki T, Gotoh J, Hamada J, Fukuuchi Y. Temporal profiles of the subcellular localization of Bim, a BH3-only protein, during middle cerebral artery occlusion in mice[J]. J Cereb Blood Flow Metab, 2002, 22(7): 810-820.
