| First Author | Harmon D | Year | 1996 |
| Journal | Mouse Genome | Volume | 94 |
| Issue | 4 | Pages | 868-70 |
| Mgi Jnum | J:39039 | Mgi Id | MGI:86637 |
| Citation | Harmon D, et al. (1996) Polymorphism of Pax7 in the wild mouse gene pool. Mouse Genome 94(4):868-70 |
| abstractText | Full text of Mouse Genome contribution: Polymorphism of Pax7 in the wild mouse gene pool. Harmon, D. and Kay, P.H. Molecular Pathology Laboratory, Department of Pathology, The University of Western Australia, Nedlands, Western Australia, 6907, Australia. Telephone: (09) 346 2993; E-mail: peterkay @uniwa.uwa.edu.au; Fax: (09) 346 2891 During our studies aimed at understanding the genetic factors which influence efficiency of regrowth of mechanically damaged skeletal muscle it became apparent that one of earliest myogenic genes isolated, Myo-Dl was markedly polymorphic (1, 2). Different allelic forms of Myo-Dl were shown to be able to distinguish between sub-species of Mus mus (3). One of the members of the Pax gene family, Pax7, has also been shown to be involved in myogenesis as well as neurogenesis (4,5). Pax7 is characterised by the presence of a highly conserved paired box, an octapeptide encoding region and a homeobox (4). As part of our continuing myogenic studies we have shown that the homeobox region of Pax7 is also polymorphic among inbred laboratory mice. Thus far four different allelic forms of Pax7 have been identified. The four different Pax7 alleles are represented in DNA from SJL/J, BALB/c, A/J and C57BL/6J mice (Kay et al., unpublished observations). Some of the different allelic forms of Pax7 are associated with enhanced regrowth of mechanically damaged skeletal muscle in laboratory mice (6 and Kay et al., unpublished observations). With a view to extending our studies on the genetic control of regrowth of damaged skeletal muscle; the distribution of different structural forms of Pax7 in the Mus mus (M.m.) gene pool has been determined. DNA from thirteen mice derived from the wild mouse gene pool was obtained from outbred colonies maintained at the Institut des Sciences dell'Evolution in Montpellier, France. Each colony was produced from a small number of wild mice captured from the geographical locations indicated in Table 1. Six were of the substrain M. m. domesticus, five were classified as M.m. musculus, and a further two represented different strains (7) as shown in Table 1. Inbred laboratory strains of SJL/J, BALB/c, A/J and C57BL/6J were obtained from the Animal Resources Centre at Murdoch University, Perth, Western Australia, and were used as controls. The sizes of TaqI fragments hybridising with the 144 and 133-bp Pax7 sub-probes (6) are summarised in Table 1. As we have previously shown, the SJL/J type of Pax7 gene, which is also found in DDO and Quackenbush mice (6), is marked by a 1.0-kb TaqI/ 144-bp subprobe fragment and fragments of 0.85 and 0.15 kb hybridising with the 133-bp subprobe. DNA from mouse strains MGT, DMZ and DGA share the same fragments. DNA from the DMZ mouse also has a 2.5-kb TaqI fragment co-hybridising with both the 133 and 144-bp sub-probes, suggesting heterozygosity for the SJL/J type of Pax7 allele and a further allele marked by the 2.5-kb fragment not found in inbred laboratory mice. The same 2.5-kb co-hybridising fragment is also found in MPR, MBK and THE mice. Pax7 in the STF (M. spretus) mouse has structural similarities with the SJL/J type of allele in the central region of Pax7 but differs in the downstream region. TABLE 1 (Legend). Distribution of fragment sizes hybridising with the 144-bp and the 133-bp Pax7 sub-probes following digestion of genomic DNA from various inbred laboratory and wild mice with TaqI. Note: Mmm= Mus mus musculus; Mmd = Mus mus domesticus; Ms = Mus spretus; Mmb = Mus mus bactrianus; ILM = inbred laboratory mice. The A/J type of Pax7 allele is identified by the presence of a 2.4-kb TaqI fragment hybridising with the 144-bp sub-probe and 1.3 and 0.15-kb fragments hybridising with the 133-bp sub-probe. MGL, BFM, BIR and MGA mice all appear to be homozygous for the A/J type of Pax7 allele. The BALB/c type of Pax7 allele is marked by a 1.2-kb TaqI/ 133-bp sub-probe fragment which also co-hybridises with the 144-bp sub-probe and a 0.85-kb fragment hybridising with the 133-bp sub-probe only. MPR also has the same 1.2-kb/ 144 and- 133-bp sub-probe hybridising fragment as BALB/c mice but lacks the 0.85-kb/ 133-bp sub-probe fragment. As indicated above, the MPR mouse also has the 2.5-kb co- hybridizing fragment as DMZ, MBK and TEH. A further type of Pax7 allele found in C57BL/6J mice is reflected by the presence of a 2.3-kb fragment hybridising with both the 144 and 133-bp sub-probes and a 0.85-kb fragment hybridising with the 133-bp sub-probe only. DNA from DBV has the same size fragments as well as a 2.4-kb/ 144-bp sub-probe fragment and fragments of 0.15 and 0.4 kb hybridising with the 133-bp sub-probe. As indicated in Table 1, MBK and TEH mice have Pax7 alleles not found in laboratory mice thus far. Figure I. (a) (Legend). Illustration of fragment sizes hybridising with the 144-bp Pax7 sub-probe following digestion of genomic DNA with TaqI. Lanes 1, 2 and 3 contain DNA from A/J, SJL/J and BALB/c respectively. The samples in lanes 6 and 10 (STF and DDO) have the 1.0 kb fragment seen in SJL/J mice, and the samples in lanes 4 and 5 (BFM and BIR) have a 2.4 kb fragment, the same as is seen in DNA from A/J mice. The samples in lane 7 and 8 (DGA and DMZ) appear to be heterozygotes, having both a 1.0 kb fragment (SJL/J type) and previously unseen fragments of size 2.7 and 2.5-kb respectively. The sample in lane 11 (DBV) is presumed to be heterozygous, reflected by the 2.3 and 2.4-kb fragments. The 2.3 and 2.4-kb fragments are similar to fragment sizes seen in C57BL/6J and A/J respectively, whilst lane 9 (TEH) appears to be homozygous for the 2.5-kb allele. (b) Illustration of fragment sizes hybridising with the 133-bp Pax7 sub-probe following digestion of genomic DNA with TaqI. Lanes 3, 4 and 5 contain DNA from SJL/J, BALB/c and A/J respectively. Lane 2 (DGA) has restriction fragments of 0.15 and 0.85-kb, the same as is seen in DNA from SJL/J mice, whilst lane 6 (MGL) has restriction fragments of size 0.15 and 1.3-kb, like those seen in DNA from A/J mice. Lane 7 (STF) has two unique fragments of 0.4 and 1.8-kb; and, lane 1 (TEH) shows the 0.85-kb fragment and the same sized co-hybridising fragment of 2.5-kb as seen in DMZ, MPR and MBK mice. Methods: DNA isolation, digestion, Southern blotting and autoradiographic methods and the Pax7 sub-probes sequences were as described previously (6). These studies have shown that Pax7 is highly polymorphic, at least 9 different alleles have been found thus far in the wild mouse gene pool. Even though Pax7 is highly polymorphic, almost 62% of wild mice, derived from many different geographical locations, have either the SJL/J or A/J type of Pax7 allele. It is of interest that, in contrast to the Pax7 alleles found in C57BL/6J and BALB/c mice, the SJL/J and A/J type of Pax7 alleles are associated with enhanced regrowth of damaged skeletal muscle (6 and unpublished results). Interestingly, the BALB/c type of Pax7 allele is not represented in this small sample of the wild mouse gene pool. Unlike Myo-D1 (3) Pax7 alleles do not distinguish between M. m. musculus and M. m. domesticus mice, therefore it is possible that structural polymorphism of Pax7 may have evolved prior to sub- speciation. It will be of interest to determine whether any of the other forms of Pax7 identified in this study affect efficiency of regrowth of damaged skeletal muscle or biological features of other tissues in which Pax7 is expressed. ACKNOWLEDGMENTS This work was supported by the National Health and Medical Research Council of Australia. REFERENCES 1. Davies, R.L., Weintraub, H., Lassar, A.B. Cell 51: 987-1000 (1987). 2. Kay, P.H., Marlow, S.A., Mitchell, C.A., Papadimitriou, J.M. Gene 124: 215-222 (1993). 3. Marlow, S.A., Kay, P.H. and Papadimitriou, J.M. Mouse Genome 93: 436-438 (1995). 4. Jostes, B., Walther, C., Gruss P. Mech. of Dev. 33: 27-37 (1991). 5. Stoykova, A., Gross, P. J. Neurosci. 14: 1395-1412 (1994). 6. Kay, P.H., Mitchell, C.A., Akkari, A., Papadimitriou, J.M. Gene 163: 171-177 (1995). 7. Potter, M. Current Topics Microbiol. Immunol. 127: 373-395 (1986). |
