title: CSN maintains the germline cellular microenvironment and controls the level of stem cell genes via distinct CRLs in testes of Drosophila melanogaster.
abstract: Stem cells and their daughters are often associated with and depend on cues from their cellular microenvironment. In Drosophila testes, each Germline Stem Cell (GSC) contacts apical hub cells and is enclosed by cytoplasmic extensions from two Cyst Stem Cells (CySCs). Each GSC daughter becomes enclosed by cytoplasmic extensions from two CySC daughters, called cyst cells. CySC fate depends on an Unpaired (Upd) signal from the hub cells, which activates the Janus Kinase and Signal Transducer and Activator of Transcription (Jak/STAT) pathway in the stem cells. Germline enclosure depends on Epidermal Growth Factor (EGF) signals from the germline to the somatic support cells. Expression of RNA-hairpins against subunits of the COnstitutively Photomorphogenic-9- (COP9-) signalosome (CSN) in somatic support cells disrupted germline enclosure. Furthermore, CSN-depleted somatic support cells in the CySC position next to the hub had reduced levels of the Jak/STAT effectors Zinc finger homeotic-1 (Zfh-1) and Chronologically inappropriate morphogenesis (Chinmo). Knockdown of CSN in the somatic support cells does not disrupt EGF and Upd signal transduction as downstream signal transducers, phosphorylated STAT (pSTAT) and phosphorylated Mitogen Activated Protein Kinase (pMAPK), were still localized to the somatic support cell nuclei. The CSN modifies fully formed Cullin RING ubiquitin ligase (CRL) complexes to regulate selective proteolysis. Reducing cullin2 (cul2) from the somatic support cells disrupted germline enclosure, while reducing cullin1 (cul1) from the somatic support cells led to a low level of Chinmo. We propose that different CRLs enable the responses of somatic support cells to Upd and EGF.
authors.affiliation: (a)University of Georgia, Department of Cellular Biology, Athens, GA 30602, USA; Ripon College, Department of Biology, Ripon, WI 54971, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Qian
authors.affiliation: (a)University of Georgia, Department of Cellular Biology, Athens, GA 30602, USA.
authors.forename: Chun L
authors.initials: CL
authors.lastname: Ng
authors.affiliation: (a)University of Georgia, Department of Cellular Biology, Athens, GA 30602, USA. Electronic address: cschulz@uga.edu.
authors.forename: Cordula
authors.initials: C
authors.lastname: Schulz
mesh_terms: D000818:Animals; D019070:Cell Lineage; D003433:Crosses, Genetic; D044842:Cullin Proteins / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000196:embryology; D005854:Germ Cells / Q000502:physiology; D053612:Janus Kinases / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D008856:Microscopy, Fluorescence; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D012313:RNA / Q000032:analysis; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D050791:STAT Transcription Factors / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology*; D013737:Testis / Q000196:embryology* / Q000473:pathology*
chemical_list: C515167:Chinmo protein, Drosophila; C100318:Cullin 1; D044842:Cullin Proteins; D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; D012097:Repressor Proteins; D050791:STAT Transcription Factors; C081010:zfh1 protein, Drosophila; D012313:RNA; D053612:Janus Kinases
keywords: CRL; CSN; Cellular microenvironment; Stem cells