title: Hedgehog is required for CySC self-renewal but does not contribute to the GSC niche in the Drosophila testis.
abstract: The Drosophila testis harbors two types of stem cells: germ line stem cells (GSCs) and cyst stem cells (CySCs). Both stem cell types share a physical niche called the hub, located at the apical tip of the testis. The niche produces the JAK/STAT ligand Unpaired (Upd) and BMPs to maintain CySCs and GSCs, respectively. However, GSCs also require BMPs produced by CySCs, and as such CySCs are part of the niche for GSCs. Here we describe a role for another secreted ligand, Hedgehog (Hh), produced by niche cells, in the self-renewal of CySCs. Hh signaling cell-autonomously regulates CySC number and maintenance. The Hh and JAK/STAT pathways act independently and non-redundantly in CySC self-renewal. Finally, Hh signaling does not contribute to the niche function of CySCs, as Hh-sustained CySCs are unable to maintain GSCs in the absence of Stat92E. Therefore, the extended niche function of CySCs is solely attributable to JAK/STAT pathway function.
authors.affiliation: Department of Biochemistry and Molecular Biology, New York University School of Medicine, New York, NY 10016, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Amoyel
authors.forename: Justina
authors.initials: J
authors.lastname: Sanny
authors.forename: Michael
authors.initials: M
authors.lastname: Burel
authors.forename: Erika A
authors.initials: EA
authors.lastname: Bach
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D029721:Drosophila Proteins / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster; D005854:Germ Cells / Q000166:cytology / Q000201:enzymology / Q000502:physiology; D053823:Hedgehog Proteins / Q000378:metabolism / Q000502:physiology*; D053612:Janus Kinases / Q000502:physiology; D008024:Ligands; D008297:Male; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013234:Stem Cells / Q000166:cytology* / Q000201:enzymology / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000201:enzymology / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D008024:Ligands; C077245:hh protein, Drosophila; D017853:Phosphotransferases (Alcohol Group Acceptor); D053612:Janus Kinases