title: Peripheral myelin maintenance is a dynamic process requiring constant Krox20 expression.
abstract: Onset of myelination in Schwann cells is governed by several transcription factors, including Krox20/Egr2, and mutations affecting Krox20 result in various human hereditary peripheral neuropathies, including congenital hypomyelinating neuropathy (CHN) and Charcot-Marie-Tooth disease (CMT). Similar molecular information is not available on the process of myelin maintenance. We have generated conditional Krox20 mutations in the mouse that allowed us to develop models for CHN and CMT. In the latter case, specific inactivation of Krox20 in adult Schwann cells results in severe demyelination, involving rapid Schwann cell dedifferentiation and increased proliferation, followed by an attempt to remyelinate and a block at the promyelinating stage. These data establish that Krox20 is not only required for the onset of myelination but that it is also crucial for the maintenance of the myelinating state. Furthermore, myelin maintenance appears as a very dynamic process in which Krox20 may constitute a molecular switch between Schwann cell myelination and demyelination programs.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U784, Ecole Normale Supérieure, 75230 Paris Cedex 05, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Decker
authors.forename: Carole
authors.initials: C
authors.lastname: Desmarquet-Trin-Dinh
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Taillebourg
authors.forename: Julien
authors.initials: J
authors.lastname: Ghislain
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Vallat
authors.forename: Patrick
authors.initials: P
authors.lastname: Charnay
mesh_terms: D000483:Alleles; D000818:Animals; D049109:Cell Proliferation; D051767:Early Growth Response Protein 2 / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D009186:Myelin Sheath / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D010525:Peripheral Nerves / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D051767:Early Growth Response Protein 2