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.[5]
PAX7 functions as a marker for a rare subset of spermatogonial stem cells, specifically a sub set of Asingle spermatogonia.[6] These PAX7+ spermatogonia are rare in adult testis but are much more prevalent in newborns, making up 28% of germ cells in neonate testis.[6] Unlike PAX7+muscle satellite cells, PAX7+ spermatogonia rapidly proliferate and are not quiescent.[6][7] PAX7+ spermatogonia are able to give rise to all stages of spermatogenesis and produce motile sperm.[6] However, PAX7 is not required for spermatogenesis, as mice without PAX7+ spermatogonia show no deficits in fertility.[6]
PAX7 may also function in the recovery in spermatogenesis. Unlike other spermatogonia, PAX7+ spermatogonia are resistant to radiation and chemotherapy.[6] 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.[6] Additionally, mice lacking PAX7 had delayed recovery of spermatogenesis following exposure to busulfan when compared to control mice.[6]
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.[3] Animal studies show that mutant mice have malformation of maxilla and the nose.[8]
↑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.
↑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.
↑Basch ML, Bronner-Fraser M, García-Castro MI (May 2006). "Specification of the neural crest occurs during gastrulation and requires Pax7". Nature. 441 (7090): 218–22. doi:10.1038/nature04684. PMID16688176.
↑Mansouri A, Stoykova A, Torres M, Gruss P (March 1996). "Dysgenesis of cephalic neural crest derivatives in Pax7-/- mutant mice". Development. 122 (3): 831–8. PMID8631261.
Further reading
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.
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.
Barr FG, Nauta LE, Davis RJ, Schäfer BW, Nycum LM, Biegel JA (Jan 1996). "In vivo amplification of the PAX3-FKHR and PAX7-FKHR fusion genes in alveolar rhabdomyosarcoma". Human Molecular Genetics. 5 (1): 15–21. doi:10.1093/hmg/5.1.15. PMID8789435.
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.
Magnaghi P, Roberts C, Lorain S, Lipinski M, Scambler PJ (September 1998). "HIRA, a mammalian homologue of Saccharomyces cerevisiae transcriptional co-repressors, interacts with Pax3". Nature Genetics. 20 (1): 74–7. doi:10.1038/1739. PMID9731536.
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.
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, Bridge JA, Crist WM, Triche TJ, Barr FG (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, Marx A, Meyer J, Lesch KP (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.
Tomescu O, Xia SJ, Strezlecki D, Bennicelli JL, Ginsberg J, Pawel B, Barr FG (August 2004). "Inducible short-term and stable long-term cell culture systems reveal that the PAX3-FKHR fusion oncoprotein regulates CXCR4, PAX3, and PAX7 expression". Laboratory Investigation. 84 (8): 1060–70. doi:10.1038/labinvest.3700125. PMID15184910.
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.