title: A comparative study of gland cells implicated in the nerve dependence of salamander limb regeneration.
abstract: Limb regeneration in salamanders proceeds by formation of the blastema, a mound of proliferating mesenchymal cells surrounded by a wound epithelium. Regeneration by the blastema depends on the presence of regenerating nerves and in earlier work it was shown that axons upregulate the expression of newt anterior gradient (nAG) protein first in Schwann cells of the nerve sheath and second in dermal glands underlying the wound epidermis. The expression of nAG protein after plasmid electroporation was shown to rescue a denervated newt blastema and allow regeneration to the digit stage. We have examined the dermal glands by scanning and transmission electron microscopy combined with immunogold labelling of the nAG protein. It is expressed in secretory granules of ductless glands, which apparently discharge by a holocrine mechanism. No external ducts were observed in the wound epithelium of the newt and axolotl. The larval skin of the axolotl has dermal glands but these are absent under the wound epithelium. The nerve sheath was stained post-amputation in innervated but not denervated blastemas with an antibody to axolotl anterior gradient protein. This antibody reacted with axolotl Leydig cells in the wound epithelium and normal epidermis. Staining was markedly decreased in the wound epithelium after denervation but not in the epidermis. Therefore, in both newt and axolotl the regenerating axons induce nAG protein in the nerve sheath and subsequently the protein is expressed by gland cells, under (newt) or within (axolotl) the wound epithelium, which discharge by a holocrine mechanism. These findings serve to unify the nerve dependence of limb regeneration.
authors.affiliation: Institute for Structural and Molecular Biology, University College London, London, UK.
authors.forename: Anoop
authors.initials: A
authors.lastname: Kumar
authors.forename: Graham
authors.initials: G
authors.lastname: Nevill
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Brockes
authors.forename: Andrew
authors.initials: A
authors.lastname: Forge
mesh_terms: D000558:Ambystoma mexicanum / Q000378:metabolism / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D005121:Extremities / Q000294:innervation* / Q000502:physiology; D059630:Mesenchymal Stem Cells / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009416:Nerve Regeneration / Q000502:physiology; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012038:Regeneration / Q000502:physiology*; D016415:Sequence Alignment; D014562:Caudata / Q000378:metabolism / Q000502:physiology*
chemical_list: D011506:Proteins
references.citation: Gene Expr Patterns. 2007 Feb;7(4):452-60
references.pmid: 17175205
references.citation: Nature. 2009 Jul 2;460(7251):60-5
references.pmid: 19571878
references.citation: J Bone Joint Surg Am. 2009 Jul;91 Suppl 4:90-8
references.pmid: 19571075
references.citation: J Anat. 1992 Oct;181 ( Pt 2):365-7
references.pmid: 1295874
references.citation: Annu Rev Cell Dev Biol. 2008;24:525-49
references.pmid: 18598212
references.citation: Anat Rec. 1966 Mar;154(3):685-99
references.pmid: 5950506
references.citation: J Anat. 1989 Dec;167:95-102
references.pmid: 2630544
references.citation: Am J Pathol. 2009 Nov;175(5):1848-57
references.pmid: 19834055
references.citation: Curr Top Microbiol Immunol. 2004;280:1-70
references.pmid: 14594207
references.citation: J Exp Zool. 1976 Feb;195(2):253-62
references.pmid: 1262816
references.citation: J Embryol Exp Morphol. 1984 Feb;79:97-112
references.pmid: 6716048
references.citation: Br J Cancer. 2003 Feb 24;88(4):579-85
references.pmid: 12592373
references.citation: Science. 1984 Sep 21;225(4668):1280-7
references.pmid: 6474177
references.citation: Q Rev Biol. 1952 Jun;27(2):169-200
references.pmid: 14949331
references.citation: Mech Dev. 1998 Mar;72(1-2):115-30
references.pmid: 9533957
references.citation: Mol Phylogenet Evol. 2005 Sep;36(3):734-40
references.pmid: 15935701
references.citation: Comp Biochem Physiol B Biochem Mol Biol. 2009 Apr;152(4):397-404
references.pmid: 19266620
references.citation: Z Mikrosk Anat Forsch. 1971;84(1):1-25
references.pmid: 5139157
references.citation: Science. 1997 Apr 4;276(5309):81-7
references.pmid: 9082990
references.citation: Science. 2007 Nov 2;318(5851):772-7
references.pmid: 17975060
references.citation: Cold Spring Harb Protoc. 2009 Aug;2009(8):pdb.emo128
references.pmid: 20147230
references.citation: Cell. 1989 Jul 14;58(1):171-80
references.pmid: 2752418
references.citation: Differentiation. 1998 Sep;63(5):238-46
references.pmid: 9810702
references.citation: Exp Neurol. 1976 Dec;53(3):610-9
references.pmid: 1036723
references.citation: Proc Natl Acad Sci U S A. 2009 Apr 28;106(17):6950-5
references.pmid: 19359471
references.citation: J Biophys Biochem Cytol. 1961 Jul;10:457-63
references.pmid: 13712435
references.citation: Dev Cell. 2002 Oct;3(4):547-55
references.pmid: 12408806
references.citation: J Morphol. 1992 Feb;211(2):165-78
references.pmid: 1556738
references.citation: Cancer Res. 2008 Jan 15;68(2):492-7
references.pmid: 18199544
references.citation: PLoS One. 2009 Sep 22;4(9):e7123
references.pmid: 19771161
references.citation: Dev Biol. 2004 Jun 1;270(1):135-45
references.pmid: 15136146
references.citation: Biochem Biophys Res Commun. 1998 Oct 9;251(1):111-6
references.pmid: 9790916
references.citation: Cell Tissue Res. 1977 Jul 15;181(3):369-93
references.pmid: 884711
references.citation: Mol Cell Proteomics. 2004 Jun;3(6):534-47
references.pmid: 14967811
references.citation: J Microsc. 1987 Jul;147(Pt 1):89-101
references.pmid: 3305958
references.citation: Z Mikrosk Anat Forsch. 1971;83(4):472-506
references.pmid: 5166122
references.citation: J Biochem Mol Biol. 2007 Mar 31;40(2):212-7
references.pmid: 17394771
references.citation: Dev Biol. 2000 May 15;221(2):273-84
references.pmid: 10790325