PgmNr M284: An inducible dominant negative allele of Sox10 models neurocristopathy deficits characteristic of PCWH patients.

Authors:
M. Southard-Smith ¹ ; M. Halaka ¹ ; N. J. Lawler ¹ ; J. M. DeKeyser ¹ ; J. Corpening Rosebrock ¹ ; S. Arpag ¹ ; J. Li ¹ ; A. Economides ² ; A. Braun ³ ; K. H. Schäfer ³ ; K. Boyd ¹

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Institutes
1) Vanderbilt University Medical Center, Nashville, TN; 2) Regeneron Pharmaceuticals Inc., Tarrytown, NY; 3) University of Applied Sciences Kaiserslautern, Zweibrücken, RLP, GER.

Abstract:

Sox10 is a transcription factor that is essential for development of a wide range of cell fates including oligodendrocytes and neural crest-derived neurons and glia of the peripheral and enteric nervous systems, melanocytes in the skin, craniofacial bones, teeth, and the adrenal medulla.  Investigating Sox10 function in these distinct lineages has been difficult because simple gene knockouts cause complete loss of gene expression in early neural crest leading to embryonic lethality.  Efforts to temporally ablate Sox10 through gene knockout strategies have been hampered by kinetics of mRNA and protein decay.  We have generated and characterized a COnditional INducible (“COIN”) dominant negative allele of Sox10 in mice as a novel tool for temporal and cell type specific analysis of gene function.  Mice bearing a COIN cassette in the Sox10 locus appear normal until Cre action flips a fluorescently tagged dominant negative Sox10 isoform into the coding frame of exon four.  Our characterization of this new allele indicates that the COIN cassette functions in a dominant negative fashion and fluorescently labels neural crest derivatives following Cre action. Crosses of Sox10-COIN mice with Cre drivers produce mutant progeny (B6J.B6N-Sox10^tm1.1Sout or Sox10-COIN^INV+) that exhibit hypopigmentation, deficits in central and peripheral glia as well as gastrointestinal phenotypes.  Sox10-COIN^INV+ pups show spotting accompanied by coat color variegation. We have named this new allele “Merle” based on the coat color variegation similarity to blue merle dogs.  At P10 Merle pups exhibit peripheral limb weakness and instability in tracking. By P15 Merle mutants are severely affected with motor deficits, circling, and difficulty in righting.  Histological and functional analysis of Merle tissues has identified central and peripheral neuropathy that is consistent with phenotypes reported in patients afflicted by the complex neurocristopathy called Peripheral Demyelinating Neuropathy, Central Dysmyelinating Leukodystrophy, Waardenburg Syndrome, and Hirschsprung Disease (PCWH).  The availability of this new allele will provide mechanistic insight into the pathology suffered by PCWH patients and permit manipulation of distinct neural crest lineages.