title: In vivo neuronal subtype-specific targets of Atoh1 (Math1) in dorsal spinal cord.
abstract: Neural basic helix-loop-helix (bHLH) transcription factors are crucial in regulating the differentiation and neuronal subtype specification of neurons. Precisely how these transcription factors direct such processes is largely unknown due to the lack of bona fide targets in vivo. Genetic evidence suggests that bHLH factors have shared targets in their common differentiation role, but unique targets with respect to their distinct roles in neuronal subtype specification. However, whether neuronal subtype-specific targets exist remains an unsolved question. To address this question, we focused on Atoh1 (Math1), a bHLH transcription factor that specifies distinct neuronal subtypes of the proprioceptive pathway in mammals including the dI1 (dorsal interneuron 1) population of the developing spinal cord. We identified transcripts unique to the Atoh1-derived lineage using microarray analyses of specific bHLH-sorted populations from mouse. Chromatin immunoprecipitation-sequencing experiments followed by enhancer reporter analyses identified five direct neuronal subtype-specific targets of Atoh1 in vivo along with their Atoh1-responsive enhancers. These targets, Klf7, Rab15, Rassf4, Selm, and Smad7, have diverse functions that range from transcription factors to regulators of endocytosis and signaling pathways. Only Rab15 and Selm are expressed across several different Atoh1-specified neuronal subtypes including external granule cells (external granule cell layer) in the developing cerebellum, hair cells of the inner ear, and Merkel cells. Our work establishes on a molecular level that neuronal differentiation bHLH transcription factors have distinct lineage-specific targets.
authors.affiliation: Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA.
authors.forename: Helen C
authors.initials: HC
authors.lastname: Lai
authors.forename: Tiemo J
authors.initials: TJ
authors.lastname: Klisch
authors.forename: Rene
authors.initials: R
authors.lastname: Roberts
authors.forename: Huda Y
authors.initials: HY
authors.lastname: Zoghbi
authors.forename: Jane E
authors.initials: JE
authors.lastname: Johnson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D002642:Chick Embryo; D047369:Chromatin Immunoprecipitation / Q000379:methods; D019295:Computational Biology; D018274:Electroporation / Q000379:methods; D004622:Embryo, Mammalian; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics; D018398:Homeodomain Proteins / Q000378:metabolism; D016547:Kinesins / Q000235:genetics; D060850:LIM-Homeodomain Proteins; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger; D015398:Signal Transduction / Q000235:genetics; D013116:Spinal Cord / Q000166:cytology*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051792:Basic Helix-Loop-Helix Proteins; D049452:Green Fluorescent Proteins; D018398:Homeodomain Proteins; D016547:Kinesins; D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C500943:Atoh1 protein, mouse; C489784:Lhx2 protein, mouse; C486336:Neurog1 protein, mouse; C543639:Kif7 protein, mouse