title: The Mammalian Orthologs of Drosophila Lgd, CC2D1A and CC2D1B, Function in the Endocytic Pathway, but Their Individual Loss of Function Does Not Affect Notch Signalling.
abstract: CC2D1A and CC2D1B belong to the evolutionary conserved Lgd protein family with members in all multi-cellular animals. Several functions such as centrosomal cleavage, involvement in signalling pathways, immune response and synapse maturation have been described for CC2D1A. Moreover, the Drosophila melanogaster ortholog Lgd was shown to be involved in the endosomal trafficking of the Notch receptor and other transmembrane receptors and physically interacts with the ESCRT-III component Shrub/CHMP4. To determine if this function is conserved in mammals we generated and characterized Cc2d1a and Cc2d1b conditional knockout mice. While Cc2d1b deficient mice displayed no obvious phenotype, we found that Cc2d1a deficient mice as well as conditional mutants that lack CC2D1A only in the nervous system die shortly after birth due to respiratory distress. This finding confirms the suspicion that the breathing defect is caused by the central nervous system. However, an involvement in centrosomal function could not be confirmed in Cc2d1a deficient MEF cells. To analyse an influence on Notch signalling, we generated intestine specific Cc2d1a mutant mice. These mice did not display any alterations in goblet cell number, proliferating cell number or expression of the Notch reporter Hes1-emGFP, suggesting that CC2D1A is not required for Notch signalling. However, our EM analysis revealed that the average size of endosomes of Cc2d1a mutant cells, but not Cc2d1b mutant cells, is increased, indicating a defect in endosomal morphogenesis. We could show that CC2D1A and its interaction partner CHMP4B are localised on endosomes in MEF cells, when the activity of the endosomal protein VPS4 is reduced. This indicates that CC2D1A cycles between the cytosol and the endosomal membrane. Additionally, in rescue experiments in D. melanogaster, CC2D1A and CC2D1B were able to functionally replace Lgd. Altogether our data suggest a functional conservation of the Lgd protein family in the ESCRT-III mediated process in metazoans.
authors.affiliation: Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Nadja
authors.initials: N
authors.lastname: Drusenheimer
authors.affiliation: Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Migdal
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Jäckel
authors.affiliation: Institut für Molekularbiologie OE5250, Medizinische Hochschule Hannover, Hannover, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Tveriakhina
authors.affiliation: Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Scheider
authors.affiliation: Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Schulz
authors.affiliation: Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Jieny
authors.initials: J
authors.lastname: Gröper
authors.affiliation: Biological and Medical Research Center (BMFZ), Genomics and Transcriptomics Laboratory (GTL), Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Köhrer
authors.affiliation: Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Klein
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D018385:Centrosome / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D051881:Receptor, Notch1; D051880:Receptors, Notch; D012097:Repressor Proteins; D025521:Tumor Suppressor Proteins; D033921:Vesicular Transport Proteins; C558469:CC2D1B protein, mouse; C000607336:CHMP4B protein, mouse; C522738:Cc2d1a protein, mouse; C497762:Notch1 protein, mouse; C515862:l(2)gd1 protein, Drosophila