ALTERNATE PAX7 TRANSCRIPTS ARE EXPRESSED SPECIFICALLY IN SKELETAL-MUSCLE, BRAIN AND OTHER ORGANS OF ADULT MICE

Pax7 is associated with formation of skeletal muscle and the neural tu be in developing embryos. Interestingly, in adult mice, rearrangements of Pax7 are associated with differences in the efficiency of skeletal muscle regrowth between mouse strains. The aim of this study was to i nvestigate the possibility that Pax7 is expressed in skeletal muscle o r other tissues from adult mice. Total RNA was isolated from adult mou se tissues and the polymerase chain reaction was performed on reverse transcribed mRNA using primers specific for regions that encode the pa ired and homeodomain of Pax7. At least four different Pax7 transcripts were found. A full-length transcript similar in sequence to that publ ished previously was identified in skeletal muscle, brain and spleen c ells of adult mice. Further putative full-length Pax7 transcripts, inc luding one that contains a hexanucleotide insertion in the paired box and one in which approximately 10 bp have been deleted in the homeobox , were found to be expressed in skeletal muscle and brain of adult mic e, respectively. A truncated Pax7 splice product comprising the paired box only was found to be expressed in most adult tissues except Liver . Results of these studies demonstrate that there are alternate transc ripts of Pax7, some of which are expressed exclusively in adult skelet al muscle and brain. It is possible that one of these transcripts may specify an alternate myogenic pathway involved in regeneration of dama ged skeletal muscle in adult mice. (C) 1997 Elsevier Science Ltd.