Guinea pig alpha 1-microglobulin/bikunin: cDNA sequencing, tissue expression and expression during acute phase

Area of Science:

• Molecular Biology
• Mammalian Genetics
• Biochemistry

Background:

• Alpha 1-microglobulin/bikunin (AMBP) is a multifunctional protein with roles in protease inhibition.
• Understanding mammalian AMBP diversity is crucial for its functional characterization.

Purpose of the Study:

• To clone and sequence the cDNA encoding alpha 1-microglobulin/bikunin (AMBP) in guinea pigs (Cavia porcellus).
• To investigate the tissue distribution of AMBP mRNA.
• To analyze AMBP mRNA expression levels during inflammation.

Main Methods:

• Reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) were used to amplify and sequence AMBP cDNA.
• RT-PCR and nested PCR were employed to detect AMBP mRNA distribution.
• Quantitative RT-PCR was used to compare AMBP mRNA levels in normal and inflamed liver tissue.

Main Results:

• The guinea pig AMBP sequence showed 69-76% amino acid identity to other mammals, featuring two Kunitz-type trypsin inhibitor domains.
• A notable difference was observed in the P1 residue of the C-terminal inhibitor domain (Gln instead of conserved Arg).
• AMBP mRNA was detected in multiple tissues including liver, pancreas, and leukocytes, but not in brain or heart.
• Inflammation did not significantly alter AMBP mRNA levels in guinea pig liver.

Conclusions:

• The study provides the first molecular characterization of guinea pig AMBP, revealing conserved and divergent features compared to other mammals.
• The widespread expression of AMBP mRNA suggests diverse physiological roles beyond the liver.
• AMBP mRNA levels appear stable under inflammatory conditions in guinea pig liver.