title: Notch signaling regulates the extent of hair cell regeneration in the zebrafish lateral line.
abstract: Mechanosensory hair cells within the zebrafish lateral line spontaneously regenerate after aminoglycoside-induced death. Exposure of 5-d-old larvae to 400 microM neomycin for 1 h results in death of almost all lateral line hair cells. Regeneration of new hair cells is observed by 24 h after neomycin treatment with nearly complete replacement by 72 h. Using bromodeoxyuridine incorporation, we show that the majority of new hair cells are generated from a transient increase in support cell proliferation that occurs between 12 and 21 h after neomycin damage. Additional observations reveal two distinct subsets of proliferating support cells within the neuromasts that differ in position, morphology, and temporal pattern of proliferation in response to neomycin exposure. We hypothesize that proliferative hair cell progenitors are located centrally within the neuromasts, whereas peripheral support cells may have a separate function. Expression of Notch signaling pathway members notch3, deltaA, and atoh1a transcripts are all upregulated within the first 24 h after neomycin treatment, during the time of maximum proliferation of support cells and hair cell progenitor formation. Treatment with a gamma-secretase inhibitor results in excess regenerated hair cells by 48 h after neomycin-induced death but has no effect without previous damage. Excess hair cells result from increased support cell proliferation. These results suggest a model where Notch signaling limits the number of hair cells produced during regeneration by regulating support cell proliferation.
authors.affiliation: Department of Biological Structure, University of Washington, Seattle, Washington 98195-7420, USA.
authors.forename: Eva Y
authors.initials: EY
authors.lastname: Ma
authors.forename: Edwin W
authors.initials: EW
authors.lastname: Rubel
authors.forename: David W
authors.initials: DW
authors.lastname: Raible
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D030801:Animals, Genetically Modified; D001973:Bromodeoxyuridine / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004625:Embryo, Nonmammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000502:physiology*; D006657:Histones / Q000235:genetics; D007814:Larva; D009355:Neomycin / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011726:Pyridinium Compounds / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D051880:Receptors, Notch / Q000502:physiology*; D012038:Regeneration / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014404:Tubulin / Q000378:metabolism; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; C073804:FM1 43; D006657:Histones; D011500:Protein Synthesis Inhibitors; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D051880:Receptors, Notch; D014404:Tubulin; D029961:Zebrafish Proteins; D049452:Green Fluorescent Proteins; D001973:Bromodeoxyuridine; D009355:Neomycin