Human Prop‐1: cloning, mapping, genomic structure

Abstract

Prop-1 is a newly isolated pituitary-specific pairedlike homeodomain transcription factor whose cDNA sequence is well known in mouse. To study its involvement in human combined pituitary hormone deficiency (CPHD), we have isolated the human cDNA ortholog and determined the exon/ intron organization and chromosomal localization of the human gene. A Prop-1 defect was characterized in three CPHD families. One missense mutation (R73C) involves a residue conserved in 95% of the more than 400 homeodomain proteins so far identified ; in vitro splicing assays demonstrated the functional importance of the second defect, whereas the remaining mutation is a frameshift. Given the disease phenotype documented in the patients, these data, which will facilitate molecular investigations in other patients, demonstrate the crucial role of Prop-1 in the proper development of somatotrophs, lactotrophs, thyreotrophs and gonadotrophs.z 1998 Federation of European Biochemical Societies.

Acquisition of Lubrol Insolubility, a Common Step for Growth Hormone and Prolactin in the Secretory Pathway of Neuroendocrine Cells

“…The properties of newly synthesized proteins were assessed immediately after a 10-min incubation with 35 S-amino acids and also during a subsequent incubation with unlabeled amino acids to follow changes as proteins progressed through the secretory pathway. At the end of a 10-min pulse with 35 S-amino acids, 35 S-prolactin is primarily located in the endoplasmic reticulum (1).…”

“…At the end of a 10-min pulse with 35 S-amino acids, 35 S-prolactin is primarily located in the endoplasmic reticulum (1). In GH 4 C 1 cells treated with hormones, over 90% of newly synthesized 35 S-prolactin was soluble when cell membranes were disrupted with Lubrol. At longer times after synthesis, some of the intracellular 35 S-prolactin became insoluble in Lubrol (Fig.…”

“…In GH 4 C 1 cells treated with hormones, over 90% of newly synthesized 35 S-prolactin was soluble when cell membranes were disrupted with Lubrol. At longer times after synthesis, some of the intracellular 35 S-prolactin became insoluble in Lubrol (Fig. 1), a property of prolactin aggregates in the dense cores of secretory granules (2).…”

“…The pellet was resuspended in lysis buffer, and immunoprecipitation followed by gel electrophoresis was carried out as described previously (22). The amount of 35 S-protein in the supernatant, pellet, and medium was quantified after gel electrophoresis using a Molecular Imager (Bio-Rad).…”

Genetic defects in GH synthesis and secretion

“…It is necessary for expression of Pit-1, for the differentiation of Pit-1-dependent cell lineage and for gonadotrope differentiation (22). PROP-1 mutations are the most common causes of genetically determined CPHD (16).…”