Expression-cloning and sequence of a cDNA encoding human growth hormone-releasing factor

Area of Science:

• Endocrinology
• Molecular Biology
• Neuroscience

Background:

• Growth hormone-releasing factor (GRF) regulates growth hormone (GH) release from the anterior pituitary.
• The minute quantities of GRF in the hypothalamus historically hindered structural determination.
• Recent isolation of GH-releasing peptides from pancreatic tumors and hypothalamus provided new avenues for research.

Purpose of the Study:

• To isolate and characterize the gene encoding human pancreatic GRF (hpGRF).
• To understand the precursor protein and potential byproducts of GRF processing.
• To confirm the genetic basis and mRNA identity of GRF from different sources.

Main Methods:

• Screening of a cDNA expression library using oligonucleotide and antibody probes.
• Isolation of a recombinant clone encoding hpGRF.
• Nucleotide sequencing and restriction analysis of genomic DNA.

Main Results:

• A recombinant clone encoding hpGRF within a larger precursor protein was isolated.
• Nucleotide sequencing predicted the generation of two additional peptides from the precursor.
• Restriction analysis suggested a single human GRF gene and identical mRNA for tumor and hypothalamic GRF.

Conclusions:

• The gene for human GRF has been identified and characterized.
• GRF is synthesized as a precursor protein, yielding additional peptides.
• The findings confirm the identity of GRF isolated from pancreatic tumors and the hypothalamus, clarifying its role in GH regulation.