TY - JOUR

T1 - Activation of protein kinase C or cAMP-dependent protein kinase increases phosphorylation of the c-erbA-encoded thyroid hormone receptor and of the v-erbA-encoded protein.

AU - Goldberg, Y

AU - Glineur, C

AU - Gesquière, J C

AU - Ricouart, A

AU - Sap, J

AU - Vennström, B

AU - Ghysdael, J

N1 - Keywords: Alpharetrovirus; Animals; Base Sequence; Cell Line, Transformed; Chick Embryo; Enzyme Activation; Gene Expression Regulation; Oncogene Proteins v-erbA; Peptide Fragments; Peptide Mapping; Phosphorylation; Precipitin Tests; Protein Kinase C; Protein Kinases; Proto-Oncogene Proteins; Proto-Oncogenes; Receptors, Thyroid Hormone; Retroviridae Proteins

PY - 1988

Y1 - 1988

N2 - The c-erbA proto-oncogene encodes a nuclear receptor for thyroid hormone (T3), which is believed to stimulate transcription from specific target promoters upon binding to cis-acting DNA sequence elements. The v-erbA oncogene of avian erythroblastosis virus (AEV) encodes a ligand-independent version of this nuclear receptor. The v-erbA product inhibits terminal differentiation of avian erythroblasts, presumably by affecting the transcription of specific genes. We show here that the c-erbA-encoded nuclear receptor (p46c-erbA) is phosphorylated on serine residues on two distinct sites. One of these sites, defined by the limit tryptic phosphopeptide 28SSQCLVK, is retained on the v-erbA-encoded P75gag-v-erbA protein. This site is located in the amino-terminal domain of these molecules, 21 amino acids upstream of the DNA-binding region. Phosphorylation of this site in both p46c-erbA and P75gag-v-erbA is enhanced 10-fold following treatment of cells with activators of either protein kinase C or cAMP-dependent protein kinase. Since cAMP-dependent protein kinase phosphorylates both p46c-erbA and P75gag-v-erbA in vitro at the same site as that observed in vivo, at least part of the cAMP-dependent phosphorylation of erbA molecules in cells could result from direct phosphorylation by this enzyme. The possible role phosphorylation may play in the function of the erbA-encoded transcriptional factors is discussed.

AB - The c-erbA proto-oncogene encodes a nuclear receptor for thyroid hormone (T3), which is believed to stimulate transcription from specific target promoters upon binding to cis-acting DNA sequence elements. The v-erbA oncogene of avian erythroblastosis virus (AEV) encodes a ligand-independent version of this nuclear receptor. The v-erbA product inhibits terminal differentiation of avian erythroblasts, presumably by affecting the transcription of specific genes. We show here that the c-erbA-encoded nuclear receptor (p46c-erbA) is phosphorylated on serine residues on two distinct sites. One of these sites, defined by the limit tryptic phosphopeptide 28SSQCLVK, is retained on the v-erbA-encoded P75gag-v-erbA protein. This site is located in the amino-terminal domain of these molecules, 21 amino acids upstream of the DNA-binding region. Phosphorylation of this site in both p46c-erbA and P75gag-v-erbA is enhanced 10-fold following treatment of cells with activators of either protein kinase C or cAMP-dependent protein kinase. Since cAMP-dependent protein kinase phosphorylates both p46c-erbA and P75gag-v-erbA in vitro at the same site as that observed in vivo, at least part of the cAMP-dependent phosphorylation of erbA molecules in cells could result from direct phosphorylation by this enzyme. The possible role phosphorylation may play in the function of the erbA-encoded transcriptional factors is discussed.

M3 - Journal article

C2 - 2903825

VL - 7

SP - 2425

EP - 2433

JO - E M B O Journal

JF - E M B O Journal

SN - 0261-4189

IS - 8

ER -