Neuropathy-associated Egr2 mutants disrupt cooperative activation of myelin protein zero by Egr2 and Sox10.
Dominant mutations in the early growth response 2 (Egr2/Krox20) transactivator, a critical regulator of peripheral myelin development, have been associated with peripheral myelinopathies. These dominant mutants interfere with the expression of genes required for myelination by Schwann cells, including that for the most abundant peripheral myelin protein, Myelin protein zero (Mpz). In this study, we show that Egr2 mutants specifically affect an Egr2-responsive element within the Mpz first intron that also contains binding sites for the transcription factor Sox10. Furthermore, Egr2 activation through this element is impaired by mutation of the Sox10 binding sites. Using chromatin immunoprecipitation assays, we found that Egr2 and Sox10 bind to this element in myelinating sciatic nerve and that a dominant Egr2 mutant does not perturb Egr2 binding but rather attenuates binding of Sox10 to the Mpz intron element. Sox10 binding at other sites of Egr2/Sox10 synergy, including a novel site in the Myelin-associated glycoprotein (Mag) gene, is also reduced by the dominant Egr2 mutant. These results provide the first demonstration of binding of Egr2/Sox10 to adjacent sites in vivo and also demonstrate that neuropathy-associated Egr2 mutants antagonize binding of Sox10 at specific sites, thereby disrupting genetic control of the myelination program.
LeBlanc
Scott E
SE
University of Wisconsin-Madison, WI 53706, USA.
Ward
Rebecca M
RM
Svaren
John
J
D000818:Animals; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D051767:Early Growth Response Protein 2 / Q000235:genetics / Q000378:metabolism*; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D007438:Introns / Q000235:genetics; D051379:Mice; D009154:Mutation / Q000235:genetics*; D018993:Myelin P0 Protein / Q000378:metabolism*; D010523:Peripheral Nervous System Diseases / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D055757:SOXE Transcription Factors; D012680:Sensitivity and Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D051767:Early Growth Response Protein 2; C497327:Egr2 protein, mouse; D006609:High Mobility Group Proteins; D018993:Myelin P0 Protein; D055757:SOXE Transcription Factors; C527924:Sox10 protein, mouse; C527925:Sox10 protein, rat; D014157:Transcription Factors