The mouse relaxin gene: nucleotide sequence and expression

Area of Science:

• Molecular Endocrinology
• Reproductive Biology
• Genomics

Background:

• Relaxin is a crucial polypeptide hormone regulating collagen remodeling and uterine contractility, particularly during pregnancy.
• Understanding relaxin's molecular characteristics is vital for comprehending reproductive physiology.

Purpose of the Study:

• To establish the sequences of relaxin cDNAs from pregnant mouse ovaries.
• To investigate the structure and genomic organization of the mouse relaxin gene.
• To determine the expression pattern of relaxin during mouse pregnancy.

Main Methods:

• Sequencing of relaxin complementary DNAs (cDNAs) derived from ovaries of late-pregnant mice.
• Polymerase chain reaction (PCR) amplification and subclone analysis.
• Direct sequencing of relaxin peptides.
• Analysis of the mouse genome for relaxin gene copy number.
• Detection of relaxin gene expression in various reproductive tissues.

Main Results:

• Identified mouse relaxin cDNAs encoding proteins identical except for isoleucine or valine at position 11 in the A chain.
• Discovered a consistent insertion of an extra tyrosine residue before the final A chain cysteine in all ovarian relaxin cDNAs.
• Confirmed the presence of a single relaxin gene in the mouse genome.
• Demonstrated significant relaxin gene expression in the ovary during pregnancy, with undetectable levels in the placenta, uterus, and fetus.

Conclusions:

• The mouse relaxin gene is expressed in the ovary during pregnancy, with a unique structural feature (tyrosine insertion) in the A chain.
• This tyrosine insertion may influence relaxin's folding and interaction with its receptor, warranting further structure-activity studies.
• Ovarian expression is the primary source of relaxin during mouse pregnancy, not the placenta, uterus, or fetus.