TY - JOUR
T1 - Coordinate regulation of peptide acetyltransferase activity and proopiomelanocortin gene expression in the intermediate lobe of the rat pituitary
AU - Millington, William R.
AU - O’Donohue, Thomas L.
AU - Chappell, Mark C.
AU - Roberts, James L.
AU - Mueller, Gregory P.
PY - 1986
Y1 - 1986
N2 - Proopiomelanocortin (POMC) is posttranslationally processed in the intermediate lobe of the pituitary to both N-terminally acetylated and nonacetylated forms of αMSH and β-endorphin (βEND). N-Acetylation substantially modifies the physiological responses produced by both peptides, suggesting that the activity of the peptide acetyltransferase, which posttranslationally acetylates βEND and des-acetyl-αMSH, may play an important role in defining the biological activity of the secretory products of the intermediate pituitary lobe. The present results demonstrate that peptide acetyltransferase activity is induced by treating rats chronically with the dopamine receptor antagonist haloperidol. Haloperidol administration produced parallel and essentially equivalent increases in acetyltransferase activity, POMC mRNA levels, and the content and secretion of POMC-derived peptides in the neurointermediate pituitary. Time-course and dose-response studies further demonstrated that acetyltransferase activity covaried with POMC mRNA and peptide levels. Chronic treatment with the dopamine receptor agonist bromocriptine had the opposite effects; it lowered acetyltranserase activity, POMC mRNA levels, and αMSH and βEND immunoreactivities. Subcellular fractionation showed that acetyltransferase activity was localized in three subcellular compartments corresponding in density to secretory vesicles, rough endoplasmic reticulum and Golgi apparatus, and cytosol. Haloperidol treatment significantly increased the specific activity of the secretory vesicle-associated acetyltransferase without affecting the specific activity of the enzymes present in the endoplasmic reticulum or cytosol. Together, these data indicate that peptide acetyltransferase activity and POMC biosynthesis are coregulated.
AB - Proopiomelanocortin (POMC) is posttranslationally processed in the intermediate lobe of the pituitary to both N-terminally acetylated and nonacetylated forms of αMSH and β-endorphin (βEND). N-Acetylation substantially modifies the physiological responses produced by both peptides, suggesting that the activity of the peptide acetyltransferase, which posttranslationally acetylates βEND and des-acetyl-αMSH, may play an important role in defining the biological activity of the secretory products of the intermediate pituitary lobe. The present results demonstrate that peptide acetyltransferase activity is induced by treating rats chronically with the dopamine receptor antagonist haloperidol. Haloperidol administration produced parallel and essentially equivalent increases in acetyltransferase activity, POMC mRNA levels, and the content and secretion of POMC-derived peptides in the neurointermediate pituitary. Time-course and dose-response studies further demonstrated that acetyltransferase activity covaried with POMC mRNA and peptide levels. Chronic treatment with the dopamine receptor agonist bromocriptine had the opposite effects; it lowered acetyltranserase activity, POMC mRNA levels, and αMSH and βEND immunoreactivities. Subcellular fractionation showed that acetyltransferase activity was localized in three subcellular compartments corresponding in density to secretory vesicles, rough endoplasmic reticulum and Golgi apparatus, and cytosol. Haloperidol treatment significantly increased the specific activity of the secretory vesicle-associated acetyltransferase without affecting the specific activity of the enzymes present in the endoplasmic reticulum or cytosol. Together, these data indicate that peptide acetyltransferase activity and POMC biosynthesis are coregulated.
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U2 - 10.1210/endo-118-5-2024
DO - 10.1210/endo-118-5-2024
M3 - Article
C2 - 2938933
AN - SCOPUS:0022646943
VL - 118
SP - 2024
EP - 2033
JO - Endocrinology
JF - Endocrinology
SN - 0013-7227
IS - 5
ER -