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Tissue-specific expression and chromosomal localization of the alpha subunit of mouse meprin A
W Jiang1, P M Sadler, N A Jenkins
1Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg 24061-0308.
Abstract:
Meprins, membrane-bound oligomeric metalloendopeptidases, contain alpha and/or beta subunits. Their activities have been found in the mouse and rat kidney. The cloned cDNA for the mouse alpha subunit of meprin A (EC cloned cDNA for the mouse alpha subunit of meprin A (EC 3.4.24.18) was used here to survey mRNA expression in kidney of different mouse strains and in various tissues of mice and rats. A single message of 3.6 kilobases was found in kidney of random bred (ICR) and inbred mice (C57BL/6, DBA/2) that contain high meprin A activity and in Sprague-Dawley rat kidney. The alpha subunit message was undetectable in the kidney of C3H/He and CBA mice, inbred strains that do not express meprin A activity. Therefore, meprin A activity in the kidney of mouse strains correlates with the amount of alpha subunit mRNA present. The 3.6-kilobase mRNA meprin alpha subunit message was also detected in the small intestine of the rat but not in mice. No message was detected in brain, heart, skeletal muscle, liver, lung, or spleen of mice or rats. Polymerase chain reaction amplification or Southern blot analysis of genomic DNA revealed that the gene for the alpha subunit is present in all mouse strains as well as in human, monkey, rat, mouse, dog, cow, rabbit, and chicken, but it was not detected in yeast. There is one gene copy present in the mouse genome. The gene was localized to mouse chromosome 17 centromeric to the major histocompatibility complex (H-2) by the interspecific backcrossing method. The localization of this allele to Mep-1, the gene previously found to regulate the expression of meprin A activity in mice, supports the proposal that Mep-1 is the structural gene for the alpha subunit.
Insights
Meprin A activity in mouse kidneys correlates with alpha subunit mRNA levels. The gene for meprin alpha subunit is present across species and located on mouse chromosome 17.
Area of Science:
- Biochemistry
- Genetics
- Molecular Biology
Background:
- Meprins are metalloendopeptidases found in mammalian kidneys.
- Meprin A comprises alpha and/or beta subunits.
- Previous studies identified meprin activity in mouse and rat kidneys.
Purpose of the Study:
- To investigate the correlation between meprin A activity and alpha subunit mRNA expression in different mouse strains and rat tissues.
- To determine the presence and localization of the meprin alpha subunit gene.
Main Methods:
- Cloned cDNA for mouse meprin alpha subunit was used to survey mRNA expression via Northern blot.
- Polymerase chain reaction (PCR) and Southern blot analyses were employed for gene detection.
- Interspecific backcrossing was used for gene localization.
Main Results:
- A 3.6 kb mRNA message for the meprin alpha subunit was detected in the kidneys of mice and rats with high meprin A activity, but not in strains lacking activity.
- The mRNA was also found in rat small intestine but not in mice.
- The meprin alpha subunit gene is present in multiple species, with one copy in the mouse genome, located on chromosome 17 near the H-2 complex.
Conclusions:
- Meprin A kidney activity in mice directly correlates with the presence of alpha subunit mRNA.
- The gene encoding the meprin alpha subunit is conserved across species.
- The gene's localization supports its identity as the Mep-1 gene, regulating meprin A expression.