An in vivo requirement for the mediator subunit med14 in the maintenance of stem cell populations.
Bottom Line: In planarians, RNAi knockdown demonstrated a requirement for med14 and many other Mediator components in adult stem cell maintenance and regeneration.Multiple stem/progenitor cell populations were observed to be reduced or absent in zebrafish med14 mutant embryos.Taken together, our results show a critical, evolutionarily conserved, in vivo function for Med14 (and Mediator) in stem cell maintenance, distinct from a general role in transcription.
Affiliation: Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.Show MeSH
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Mentions: We next sought to determine the causal log mutation, which we had previously localized to linkage group 9 (Jin et al., 2007). Further mapping defined a zero recombination region of approximately 100 kb containing four genes. RT-PCR and sequencing from mutant (s231 and the previously isolated m628 and m673 alleles) and wild-type (WT) cDNA pools identified distinct premature stop codons in med14 in all three alleles (Figure 2A). Injection of med14 morpholino recapitulated otic vesicle, pectoral fin and cardiac phenotypes, while injection of 300 pg of RNA encoding a WT form of Med14 partially rescued these defects in log mutants (Figures 2B–2E′′′). Further, injection of RNA encoding the s231, m628, and m673 forms of med14 failed to affect appreciable rescue of log mutants (results not shown). Taken together, this established that the log phenotype is due to mutation of med14.
Affiliation: Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.