The phosphoinositide-3-kinase (PI3K)/protein kinase B (PKB)/Bad signal transduction pathway is engaged in the control of apoptosis in many different cell types, particularly through phosphorylation of the Bcl-2 family protein Bad. We examined the involvement of this pathway in the control of programmed cell death in the retina of developing rats. PKB is constitutively phosphorylated in retinal tissue in vitro, whereas Bad was dephosphorylated both in Ser112 and Ser136. Cell death induced by either the PI3K inhibitor LY294002, or the general kinase inhibitor 2-aminopurine, were followed by PKB dephosphorylation, but PKB was not modulated during cell death induced by the protein synthesis inhibitor anisomycin. Treatment of retinal tissue cultures with forskolin, which increases intracellular levels of cAMP, partially blocked apoptosis induced by both anisomycin and 2-aminopurine, but not by LY294002, whereas forskolin invariably induced phosphorylation of Bad on both Ser112 and Ser136. The data suggest that Bad may be engaged in survival pathways in the immature retina, but pathways other than PI3K/PKB/Bad, and phosphorylation sites other than Ser112 and Ser136 in the Bad protein control cell survival in retinal tissue. © 2003 Wiley Periodicals, Inc.562171177Adler, R., A model of retinal cell differentiation in the chick embryo (2000) Prog Retintinal Eye Res, 19, pp. 529-557Alessi, D.R., Cohen, P., Mechanism of activation and function of protein kinase B (1998) Curr Opin Gen Dev, 8, pp. 55-62Bonni, A., Brunet, A., West, A.E., Datta, S.R., Takasu, M.A., Greenberg, M.E., Cell survival promoted by the Ras-MAKP signaling pathway by transcription-dependent and -independent mechanisms (1999) Science, 286, pp. 1358-1362Brunet, A., Bonni, A., Zigmond, M.J., Lin, M.Z., Juo, P., Hu, L.S., Anderson, M.J., Greenberg, M.E., Akt promotes cell survival by phosphorylating and inhibiting a Forkhead transcription factor (1999) Cell, 96, pp. 857-868Brunet, A., Datta, S.R., Greenberg, M.E., Transcription-dependent and -independent control of neuronal survival by the PI3-Akt signaling pathway (2001) Curr Opin Neurobiol, 11, pp. 297-305Cardone, M.H., Roy, N., Stennicke, H.R., Salvesen, G.S., Franke, T.F., Stanbridge, E., Frisch, E., Reed, J.C., Regulation of cell death protease Caspase-9 by phosphorilation (1998) Science, 282, pp. 1381-1321Chang, S.H., Cvetanovic, M., Harvey, K.J., Komoriya, A., Packard, B., Ucker, D.S., The effector phase of physiological cell death relies exclusively on the posttranslational activation of resident components (2002) Exp Cell Res, 277, pp. 15-30Datta, S.R., Dudek, H., Tao, X., Masters, S., Fu, H., Gotoh, Y., Greenberg, M.E., Akt phosphorylation of BAD couples survival signals to the cell-intrinsic death machinery (1997) Cell, 91, pp. 231-241Datta, S.R., Katsov, A., Hu, L., Petros, A., Fesik, S.W., Yaffe, M.B., Greenberg, M.E., 14-3-3 Proteins and survival kinases cooperate to inactivate Bad by BH3 domain phosphorylation (2000) Mol Cell, 6, pp. 41-51Del Peso, L., González-Garcia, M., Page, C., Herrera, R., Nuñez, G., Interleukin-3-induced phosphorylation of Bad through the protein kinase Akt (1997) Science, 278, pp. 687-689Eves, E.M., Xiong, W., Bellacosa, A., Kennedy, S.G., Tsichlis, P.N., Rosner, M.R., Hay, N., Akt, a target of phosphatidylinositol 3-kinase, inhibits apoptosis in a differentiating neuronal cell line (1998) Mol Cell Biol, 18, pp. 2143-2152Franke, T.F., Yang, S.I., Chan, T.O., Datta, K., Kazlauskas, A., Morrison, D.K., Kaplan, D.R., Tsichlis, P.N., The protein kinase encoded by the Akt proto-oncogene is a target of the PDGF-activated phosphatidylinositol 3-kinase (1995) Cell, 81, pp. 727-736Harada, H., Becknell, B., Wilm, M., Mann, M., Huang, L.J.S., Taylor, S.S., Scott, J.D., Korsmeyer, S.J., Phosphorylation and inactivation of BAD by mitochondria-anchored Protein Kinase A (1999) Mol Cell, 3, pp. 413-422Hinton, H.J., Welham, M.J., Cytokine-induced protein kinase B activation and Bad phosphorylation do not correlate with cell survival of hemopoietic cells (1999) J Immunol, 162, pp. 7002-7009Huang, E.J., Reichardt, L.F., Neurotrophins: Roles in neuronal development and function (2001) Annu Rev Neurosci, 24, pp. 677-736Linden, R., Rehen, S.K., Chiarini, L.B., Apoptosis in developing retinal tissue (1999) Prog Retinal Eye Res, 18, pp. 133-165Perry, V.H., Henderson, Z., Linden, R., Postnatal changes in retinal ganglion cell and optic axon populations in the pigmented rat (1983) J Comp Neurol, 219, pp. 356-368Rehen, S.K., Linden, R., Apoptosis in the developing retina: Paradoxical effects of protein synthesis inhibition (1994) Braz J Med Biol Res, 27, pp. 1647-1651Rehen, S.K., Varella, M.H., Freitas, F.G., Moraes, M.O., Linden, R., Contrasting effects of protein synthesis inhibition and of cyclic AMP on apoptosis in the developing retina (1996) Development, 122, pp. 1439-1448Scheid, M.P., Duronio, V., Dissociation of cytokine-induced phosphorylation of BAD and activation of PKB/Akt: Involvement of MEK upstream of BAD phosphorylation (1998) Proc Natl Acad Sci USA, 95, pp. 7439-7444Stenkamp, D.L., Cameron, D.A., Cellular pattern formation in the retina: Retinal regeneration as a model system (2002) Mol Vis, 8, pp. 280-293Takaishi, H., Konishi, H., Matsuzaki, H., Ono, Y., Shirai, Y., Saito, N., Kitamura, T., Nishizuka, Y., Regulation of nuclear translocation of Forkhead transcription factor AFX by protein kinase B (1999) Proc Natl Acad Sci USA, 96, pp. 11836-11841Tan, Y., Ruan, H., Demeter, M.R., Comb, M.J., p90RSK blocks Bad-mediated cell death via a protein kinase C-dependent pathway (1999) J Biol Chem, 274, pp. 34859-34867Tsujimoto, Y., Shimizu, S., Bcl-2 family: Life-or-death switch (2000) FEBS Lett, 466, pp. 6-10Uchida, T., Myers, M.G., White, M.F., IRS-4 mediates protein kinase B signaling during insulin stimulation without promoting antiapoptosis (2000) Mol Cell Biol, 20, pp. 126-138Varella, M.H., Correa, D.F., Campos, C.B., Chiarini, L.B., Linden, R., Protein kinases selectively modulate apoptosis in the developing retina in vitro (1997) Neurochem Int, 31, pp. 217-227Varella, M.H., De Mello, F.G., Linden, R., Evidence for an anti-apoptotic role of dopamine in developing retinal tissue (1999) J Neurochem, 73, pp. 485-492Wolf, B.B., Green, D.R., Suicidal tendencies: Apoptotic cell death by caspase family proteinases (1999) J Biol Chem, 274, pp. 20049-20052Yang, E., Zha, J., Jockel, J., Boise, L.H., Thompson, C.B., Korsmeyer, S.J., Bad, a heterotrimeric partner for Bcl-XL and Bcl-2, displaces Bax and promotes cell death (1995) Cell, 80, pp. 285-291Zha, J., Harada, H., Yang, E., Jockel, J., Korsmeyer, S.J., Serine phosphorylation of death agonist BAD in response to survival factors results in biding to 14-3-3 not BCL-XL (1996) Cell, 87, pp. 619-628