title: Shh promotes direct interactions between epidermal cells and osteoblast progenitors to shape regenerated zebrafish bone.
abstract: Zebrafish innately regenerate amputated fins by mechanisms that expand and precisely position injury-induced progenitor cells to re-form tissue of the original size and pattern. For example, cell signaling networks direct osteoblast progenitors (pObs) to rebuild thin cylindrical bony rays with a stereotypical branched morphology. Hedgehog/Smoothened (Hh/Smo) signaling has been variably proposed to stimulate overall fin regenerative outgrowth or promote ray branching. Using a photoconvertiblepatched2reporter, we resolve active Hh/Smo output to a narrow distal regenerate zone comprising pObs and adjacent motile basal epidermal cells. This Hh/Smo activity is driven by epidermal Sonic hedgehog a (Shha) rather than Ob-derived Indian hedgehog a (Ihha), which nevertheless functions atypically to support bone maturation. Using BMS-833923, a uniquely effective Smo inhibitor, and high-resolution imaging, we show that Shha/Smo is functionally dedicated to ray branching during fin regeneration. Hh/Smo activation enables transiently divided clusters of Shha-expressing epidermis to escort pObs into similarly split groups. This co-movement likely depends on epidermal cellular protrusions that directly contact pObs only where an otherwise occluding basement membrane remains incompletely assembled. Progressively separated pObs pools then continue regenerating independently to collectively re-form a now branched skeletal structure.
authors.affiliation: Institute of Molecular Biology, University of Oregon, 297A Klamath Hall, 1370 Franklin Blvd, Eugene, OR 97403, USA.|Department of Chemistry and Biochemistry, University of Oregon, 297A Klamath Hall, 1370 Franklin Blvd, Eugene, OR 97403, USA.
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Armstrong
authors.affiliation: Institute of Molecular Biology, University of Oregon, 297A Klamath Hall, 1370 Franklin Blvd, Eugene, OR 97403, USA.
authors.forename: Astra
authors.initials: A
authors.lastname: Henner
authors.affiliation: Institute of Molecular Biology, University of Oregon, 297A Klamath Hall, 1370 Franklin Blvd, Eugene, OR 97403, USA kryn@uoregon.edu sstewar2@uoregon.edu.
authors.forename: Scott
authors.initials: S
authors.lastname: Stewart
authors.affiliation: Institute of Molecular Biology, University of Oregon, 297A Klamath Hall, 1370 Franklin Blvd, Eugene, OR 97403, USA kryn@uoregon.edu sstewar2@uoregon.edu.|Department of Biology, University of Oregon, 297A Klamath Hall, 1370 Franklin Blvd, Eugene, OR 97403, USA.
authors.forename: Kryn
authors.identifier: 0000-0001-6206-0365
authors.initials: K
authors.lastname: Stankunas
mesh_terms: D058500:Animal Fins / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001485:Basement Membrane / Q000187:drug effects / Q000378:metabolism; D001549:Benzamides / Q000494:pharmacology; D001861:Bone Regeneration / Q000187:drug effects; D002113:Calcification, Physiologic / Q000187:drug effects; D002450:Cell Communication / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D000078404:Epidermal Cells; D049452:Green Fluorescent Proteins / Q000378:metabolism; D053823:Hedgehog Proteins / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology; D012038:Regeneration / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D000072086:Smoothened Receptor / Q000037:antagonists & inhibitors / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014704:Veratrum Alkaloids / Q000494:pharmacology; D015027:Zebrafish / Q000502:physiology*; D029961:Zebrafish Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C583051:BMS-833923; D001549:Benzamides; D053823:Hedgehog Proteins; C569497:Ihha protein, zebrafish; D011799:Quinazolines; C524053:Shha protein, zebrafish; D000072086:Smoothened Receptor; D014704:Veratrum Alkaloids; D029961:Zebrafish Proteins; C491021:smo protein, zebrafish; D049452:Green Fluorescent Proteins; C000541:cyclopamine
keywords: BMS-833923; Basal epidermis; Basement membrane; Bone patterning; Calcification; Caudal fins; Cyclopamine; Hedgehog signaling; Indian hedgehog; Osteoblasts; Ray branching; Regeneration; Smoothened inhibitor; Sonic hedgehog; Zebrafish