title: Vertebrate epidermal cells are broad-specificity phagocytes that clear sensory axon debris.
abstract: Cellular debris created by developmental processes or injury must be cleared by phagocytic cells to maintain and repair tissues. Cutaneous injuries damage not only epidermal cells but also the axonal endings of somatosensory (touch-sensing) neurons, which must be repaired to restore the sensory function of the skin. Phagocytosis of neuronal debris is usually performed by macrophages or other blood-derived professional phagocytes, but we have found that epidermal cells phagocytose somatosensory axon debris in zebrafish. Live imaging revealed that epidermal cells rapidly internalize debris into dynamic phosphatidylinositol 3-monophosphate-positive phagosomes that mature into phagolysosomes using a pathway similar to that of professional phagocytes. Epidermal cells phagocytosed not only somatosensory axon debris but also debris created by injury to other peripheral axons that were mislocalized to the skin, neighboring skin cells, and macrophages. Together, these results identify vertebrate epidermal cells as broad-specificity phagocytes that likely contribute to neural repair and wound healing.
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, California 90095 rasmuss@ucla.edu sagasti@mcdb.ucla.edu.
authors.forename: Jeffrey P
authors.identifier: http://orcid.org/0000-0001-6997-3773
authors.initials: JP
authors.lastname: Rasmussen
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, California 90095.
authors.forename: Georgeann S
authors.identifier: http://orcid.org/0000-0002-8394-9347
authors.initials: GS
authors.lastname: Sack
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, California 90095.
authors.forename: Seanna M
authors.initials: SM
authors.lastname: Martin
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, California 90095 rasmuss@ucla.edu sagasti@mcdb.ucla.edu.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Sagasti
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology*; D000078404:Epidermal Cells; D004817:Epidermis / Q000502:physiology*; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology*; D010586:Phagocytes / Q000378:metabolism / Q000502:physiology*; D010587:Phagocytosis; D010588:Phagosomes / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000473:pathology; D014855:Wallerian Degeneration; D015027:Zebrafish
chemical_list: D018129:Phosphatidylinositol Phosphates; C055525:phosphatidylinositol 3-phosphate
keywords: Wallerian degeneration; axon; phagocytosis; skin; somatosensory; zebrafish