Pax-7 plays a role in
neural crest development and
gastrulation, and it is an important factor in the expression of neural crest markers such as
Slug,
Sox9,
Sox10 and
HNK-1. PAX7 is expressed in the
palatal shelf of the
maxilla,
Meckel's cartilage,
mesencephalon, nasal cavity, nasal epithelium, nasal capsule and
pons. 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. PAX7 functions as a marker for a rare subset of
spermatogonial stem cells, specifically a sub set of Asingle spermatogonia. These PAX7+ spermatogonia are rare in adult
testis but are much more prevalent in newborns, making up 28% of
germ cells in neonate testis. PAX7+ spermatogonia are able to give rise to all stages of
spermatogenesis and produce motile
sperm. However, PAX7 is not required for spermatogenesis, as mice without PAX7+ spermatogonia show no deficits in fertility. PAX7 may also function in the recovery in spermatogenesis. Unlike other spermatogonia, PAX7+ spermatogonia are resistant to
radiation and
chemotherapy. 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. Additionally, mice lacking PAX7 had delayed recovery of spermatogenesis following exposure to
busulfan when compared to control mice. == Clinical significance ==