Editing Schwann cell (section)

==== Krox-20 ====

Several important transcription factors are also expressed and involved at various stages in development changing the features on the Schwann cells from an immature to mature state. One indispensable transcription factor expressed during the myelination process is Krox-20. It is a general zinc-finger transcription factor and is expressed in the rhombomeres 3 and 5.

Krox-20 is considered one of the master regulators of PNS myelination and is important in driving transcription of specific structural proteins in the myelin. It has been shown to control a set of genes responsible for interfering with this feature in the axon changing it from a pro-myelinating to myelinating state.<ref name=":4">{{Cite journal|last=Salzer|first=James|date=2015|title=Schwann cell myelination|journal= Cold Spring Harbor Perspectives in Biology|volume=7|issue=8|pages=a020529|doi=10.1101/cshperspect.a020529|pmid=26054742|pmc=4526746}}</ref> In this way, in Krox-20 double knock out mice, it has been recorded that hindbrain segmentation is affected as well as myelination of Schwann cell associated axons. Indeed, in these mice, the Schwann cells are not able to perform their myelination properly as they only wrap their cytoplasmic processes one and half turn around the axon and despite the fact that they still express the early myelin marker, late myelin gene products are absent. In addition, recent studies have also proven the importance of this transcription factor in maintaining the myelination phenotype (and requires the co-expression of Sox 10) as its inactivation leads to dedifferentiation of the Schwann cells.<ref name=":3">{{Cite journal|last1=Topilko|first1=Piotr|last2=Schneider-Maunoury|first2=Sylvie|last3=Levi|first3=Giovanni|last4=Baron-Van Evercooren|first4=Anne|last5=Chennoufi|first5=Amina Ben Younes|last6=Seitanidou|first6=Tania|last7=Babinet|first7=Charles|last8=Charnay|first8=Patrick|date=1994-10-27|title=Krox-20 controls myelination in the peripheral nervous system|journal=Nature|language=en|volume=371|issue=6500|pages=796–99|doi=10.1038/371796a0|pmid=7935840|bibcode=1994Natur.371..796T|s2cid=4333028}}</ref>