CHARACTERIZATION OF PARVALBUMIN CDNA CLONES AND GENE-EXPRESSION IN NORMAL AND DYSTROPHIC MICE OF STRAIN 129-REJ

Parvaibumin is a calcium-binding protein found in fast-twitch skeletal muscles and selected cells in the brain. In several dystrophic mutant s in the mouse, the parvalbumin content of skeletal muscles and brain is reduced and this deficiency appears to correlate with the inability of these mice to handle enhanced calcium uptake associated with the d ystrophic process. In this study, two overlapping cDNA clones of 392 a nd 1268 base pairs were isolated from a mouse cDNA library in lambda g t11, characterized, and used as probes to study the involvement of the parvalbumin gene and its expression in various tissues of dystrophic mice of strain 129 ReJ. Southern blot analyses of restriction fragment s of genomic DNA from normal and dystrophic mice indicate the same num ber and size of parvalbumin-specific gene fragments observed by other researchers, suggesting that the size of the Pva gene is the same in b oth normal and dystrophic mice of strain 129 ReJ. Northern blot analys es of total RNA from hind-limb muscles using cloned parvalbumin cDNA a s probes revealed an abundant 800-nucleotide mRNA with lesser amounts of a 1000-nucleotide mRNA transcript in both normal and dystrophic mic e of strain 129 ReJ. The amount of these mRNAs was reduced by 65-77% i n dystrophic muscles preparations and was similar to the levels of p-a ctin mRNA in these animals. These results suggest that parvalbumin gen e expression is not down regulated in dystrophic mice of strain 129 Re J.