Retinoic acid- and bone morphogenetic protein 4-induced apoptosis in P19 embryonal carcinoma cells requires p27

TY - JOUR

T1 - Retinoic acid- and bone morphogenetic protein 4-induced apoptosis in P19 embryonal carcinoma cells requires p27

AU - Glozak, Michele A.

AU - Rogers, Melissa B.

N1 - Funding Information: We thank Genetics Institute for the gift of recombinant BMP4; Drs. G. Blanck, T. Hunter, and C. Sherr for cDNA clones; and Dr. W. D. Cress for GST-RB protein. We acknowledge the use of the Molecular Imaging and Flow Cytometry Core Facilities at the H. Lee Moffitt Cancer Center and Research Institute. This work was supported by a National Institute of Child Health and Human Development grant (HD31117). M.A.G. was supported by a postdoctoral fellowship from the American Heart Association, FL Affiliate.

PY - 2001/8/15

Y1 - 2001/8/15

N2 - During development, many cells are specifically eliminated. Therefore, programmed cell death must be understood to fully elucidate embryogenesis. Retinoic acid (RA) and bone morphogenetic protein (BMP) 4 induce rapidly dividing P19 embryonal carcinoma cells to undergo apoptosis. RA alone minimally induces apoptosis, while BMP4 alone induces none. RA and BMP4 exposure also elevates the number of cells in the G1 phase of the cell cycle. Because many cell cycle proteins control both proliferation and apoptosis, we determined the role of these proteins in inducing apoptosis. Although the mRNA levels of cyclins D1 and D2 are reduced in cells undergoing apoptosis, the protein levels are not. In contrast, RA and BMP4 induce the Cdk inhibitor p27. This protein binds Cdk4 in RA- and BMP4-treated cells and inhibits Cdk4-dependent kinase activity. We used p27 antisense oligonucleotides to rescue the P19 cells from RA and BMP4 apoptosis thus proving that p27 is necessary. The Cdk4 substrate, retinoblastoma (Rb) protein, is also induced in apoptotic cells. Consistent with the decreased kinase activity of the apoptotic cells, this Rb protein is hypophosphorylated and presumably active. These data support the hypothesis that RA and BMP4 together induce the p27 protein leading to Rb activation and ultimately apoptosis.

AB - During development, many cells are specifically eliminated. Therefore, programmed cell death must be understood to fully elucidate embryogenesis. Retinoic acid (RA) and bone morphogenetic protein (BMP) 4 induce rapidly dividing P19 embryonal carcinoma cells to undergo apoptosis. RA alone minimally induces apoptosis, while BMP4 alone induces none. RA and BMP4 exposure also elevates the number of cells in the G1 phase of the cell cycle. Because many cell cycle proteins control both proliferation and apoptosis, we determined the role of these proteins in inducing apoptosis. Although the mRNA levels of cyclins D1 and D2 are reduced in cells undergoing apoptosis, the protein levels are not. In contrast, RA and BMP4 induce the Cdk inhibitor p27. This protein binds Cdk4 in RA- and BMP4-treated cells and inhibits Cdk4-dependent kinase activity. We used p27 antisense oligonucleotides to rescue the P19 cells from RA and BMP4 apoptosis thus proving that p27 is necessary. The Cdk4 substrate, retinoblastoma (Rb) protein, is also induced in apoptotic cells. Consistent with the decreased kinase activity of the apoptotic cells, this Rb protein is hypophosphorylated and presumably active. These data support the hypothesis that RA and BMP4 together induce the p27 protein leading to Rb activation and ultimately apoptosis.

KW - Apoptosis

KW - Cdk inhibitor p27

KW - Cyclins

KW - Retinoblastoma

UR - http://www.scopus.com/inward/record.url?scp=0035881281&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035881281&partnerID=8YFLogxK

U2 - 10.1006/excr.2001.5281

DO - 10.1006/excr.2001.5281

M3 - Article

C2 - 11478839

SN - 0014-4827

VL - 268

SP - 128

EP - 138

JO - Experimental cell research

JF - Experimental cell research

IS - 2

ER -