Pax7 is a transcription factor that plays a role in myogenesis through regulation of muscle precursor cells proliferation. It can bind to DNA as an heterodimer with PAX3. Also interacts with PAXBP1; the interaction links PAX7 to a WDR5-containing histone methyltransferase complex By similarity. Interacts with DAXX too.[9]
PAX7 functions as a marker for a rare subset of spermatogonial stem cells, specifically a sub set of Asingle spermatogonia.[10] These PAX7+ spermatogonia are rare in adult testis but are much more prevalent in newborns, making up 28% of germ cells in neonate testis.[10] Unlike PAX7+muscle satellite cells, PAX7+ spermatogonia rapidly proliferate and are not quiescent.[10][11] PAX7+ spermatogonia are able to give rise to all stages of spermatogenesis and produce motile sperm.[10] However, PAX7 is not required for spermatogenesis, as mice without PAX7+ spermatogonia show no deficits in fertility.[10]
PAX7 may also function in the recovery in spermatogenesis. Unlike other spermatogonia, PAX7+ spermatogonia are resistant to radiation and chemotherapy.[10] The surviving PAX7+ spermatogonia are able to increase in number following these therapies and differentiate into the other forms of spermatogonia that did not survive.[10] Additionally, mice lacking PAX7 had delayed recovery of spermatogenesis following exposure to busulfan when compared to control mice.[10]
Clinical significance
Pax proteins play critical roles during fetal development and cancer growth. The specific function of the paired box gene 7 is unknown but speculated to involve tumor suppression since fusion of this gene with a forkhead domain family member has been associated with alveolar rhabdomyosarcoma. Alternative splicing in this gene has produced two known products but the biological significance of the variants is unknown.[7] Animal studies show that mutant mice have malformation of maxilla and the nose.[12]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Stapleton P, Weith A, Urbánek P, Kozmik Z, Busslinger M (April 1993). "Chromosomal localization of seven PAX genes and cloning of a novel family member, PAX-9". Nature Genetics. 3 (4): 292–8. doi:10.1038/ng0493-292. PMID7981748. S2CID21338655.
^Pilz AJ, Povey S, Gruss P, Abbott CM (March 1993). "Mapping of the human homologs of the murine paired-box-containing genes". Mammalian Genome. 4 (2): 78–82. doi:10.1007/BF00290430. PMID8431641. S2CID30845070.
Blake J, Ziman MR (April 2003). "Aberrant PAX3 and PAX7 expression. A link to the metastatic potential of embryonal rhabdomyosarcoma and cutaneous malignant melanoma?". Histology and Histopathology. 18 (2): 529–39. PMID12647804.
Shapiro DN, Sublett JE, Li B, Valentine MB, Morris SW, Noll M (September 1993). "The gene for PAX7, a member of the paired-box-containing genes, is localized on human chromosome arm 1p36". Genomics. 17 (3): 767–9. doi:10.1006/geno.1993.1404. PMID7902328.
Cross SH, Charlton JA, Nan X, Bird AP (March 1994). "Purification of CpG islands using a methylated DNA binding column". Nature Genetics. 6 (3): 236–44. doi:10.1038/ng0394-236. PMID8012384. S2CID12847618.
Schäfer BW, Mattei MG (July 1993). "The human paired domain gene PAX7 (Hup1) maps to chromosome 1p35-1p36.2". Genomics. 17 (1): 249–51. doi:10.1006/geno.1993.1315. PMID8104868.
Vorobyov E, Mertsalov I, Dockhorn-Dworniczak B, Dworniczak B, Horst J (October 1997). "The genomic organization and the full coding region of the human PAX7 gene". Genomics. 45 (1): 168–74. doi:10.1006/geno.1997.4915. PMID9339373.
Margue CM, Bernasconi M, Barr FG, Schäfer BW (June 2000). "Transcriptional modulation of the anti-apoptotic protein BCL-XL by the paired box transcription factors PAX3 and PAX3/FKHR". Oncogene. 19 (25): 2921–9. doi:10.1038/sj.onc.1203607. PMID10871843. S2CID23943294.
Kondrashov AV, Pospelov VA (2002). "[In vitro modelling of the interactions between the promoter and enhancer complexes]". Tsitologiia. 43 (8): 764–71. PMID11601392.
Sorensen PH, Lynch JC, Qualman SJ, Tirabosco R, Lim JF, Maurer HM, et al. (June 2002). "PAX3-FKHR and PAX7-FKHR gene fusions are prognostic indicators in alveolar rhabdomyosarcoma: a report from the children's oncology group". Journal of Clinical Oncology. 20 (11): 2672–9. doi:10.1200/JCO.2002.03.137. PMID12039929.
Syagailo YV, Okladnova O, Reimer E, Grässle M, Mössner R, Gattenlöhner S, et al. (July 2002). "Structural and functional characterization of the human PAX7 5'-flanking regulatory region". Gene. 294 (1–2): 259–68. doi:10.1016/S0378-1119(02)00798-9. PMID12234688.
Vorobyov E, Horst J (November 2004). "Expression of two protein isoforms of PAX7 is controlled by competing cleavage-polyadenylation and splicing". Gene. 342 (1): 107–12. doi:10.1016/j.gene.2004.07.030. PMID15527970.