Stability of proICA512/IA-2 and its targeting to insulin secretory granules require β4-sheet-mediated dimerization of its ectodomain in the endoplasmic reticulum

The type 1 diabetes autoantigen ICA512/IA-2/RPTPN is a receptor protein tyrosine phosphatase of the insulin secretory granules (SGs) which regulates the size of granule stores, possibly via cleavage/signaling of its cytosolic tail. The role of its extracellular region remains unknown. Structural studies indicated that β2- or β4-strands in the mature ectodomain (ME ICA512) form dimers in vitro. Here we show that ME ICA512 prompts proICA512 dimerization in the endoplasmic reticulum. Perturbation of ME ICA512 β2-strand N-glycosylation upon S508A replacement allows for proICA512 dimerization, O-glycosylation, targeting to granules, and conversion, which are instead precluded upon G553D replacement in the ME ICA512 β4-strand. S508A/G553D and N506A/G553D double mutants dimerize but remain in the endoplasmic reticulum. Removal of the N-terminal fragment (ICA512-NTF) preceding ME ICA512 allows an ICA512-ΔNTF G553D mutant to exit the endoplasmic reticulum, and ICA512-ΔNTF is constitutively delivered to the cell surface. The signal for SG sorting is located within the NTF RESP18 homology domain (RESP18-HD), whereas soluble NTF is retained in the endoplasmic reticulum. Hence, we propose that the ME ICA512 β2-strand fosters proICA512 dimerization until NTF prevents N506 glycosylation. Removal of this constraint allows for proICA512 β4-strand-induced dimerization, exit from the endoplasmic reticulum, O-glycosylation, and RESP18-HD-mediated targeting to granules.Instituto Multidisciplinario de Biología Celula

Stability of proICA512/IA-2 and its targeting to insulin secretory granules require β4-sheet-mediated dimerization of its ectodomain in the endoplasmic reticulum

The type 1 diabetes autoantigen ICA512/IA-2/RPTPN is a receptor protein tyrosine phosphatase of the insulin secretory granules (SGs) which regulates the size of granule stores, possibly via cleavage/signaling of its cytosolic tail. The role of its extracellular region remains unknown. Structural studies indicated that β2- or β4-strands in the mature ectodomain (ME ICA512) form dimers in vitro. Here we show that ME ICA512 prompts proICA512 dimerization in the endoplasmic reticulum. Perturbation of ME ICA512 β2-strand N-glycosylation upon S508A replacement allows for proICA512 dimerization, O-glycosylation, targeting to granules, and conversion, which are instead precluded upon G553D replacement in the ME ICA512 β4-strand. S508A/G553D and N506A/G553D double mutants dimerize but remain in the endoplasmic reticulum. Removal of the N-terminal fragment (ICA512-NTF) preceding ME ICA512 allows an ICA512-ΔNTF G553D mutant to exit the endoplasmic reticulum, and ICA512-ΔNTF is constitutively delivered to the cell surface. The signal for SG sorting is located within the NTF RESP18 homology domain (RESP18-HD), whereas soluble NTF is retained in the endoplasmic reticulum. Hence, we propose that the ME ICA512 β2-strand fosters proICA512 dimerization until NTF prevents N506 glycosylation. Removal of this constraint allows for proICA512 β4-strand-induced dimerization, exit from the endoplasmic reticulum, O-glycosylation, and RESP18-HD-mediated targeting to granules.Instituto Multidisciplinario de Biología Celula

Specific epibacterial communities on macroalgae: phylogeny matters more than habitat

Epibacterial communities on thalli of the algal species Fucus serratus, Fucus vesiculosus, Laminaria saccharina, Ulva compressa, Delesseria sanguinea and Phycodrys rubens were analysed using 16S ribosomal RNA gene-based DGGE. Individuals of all species were collected in the Kiel Fjord (Baltic Sea) and in the rocky intertidal of Helgoland (North Sea). DGGE gels as well as cluster and multidimensional scaling analysis based on the DGGE band patterns of the epibacterial community showed significant differences between the epibacterial communities on the investigated algal species both in the Baltic and North Seas. Epibacterial communities differed less between regions than between host species, and were more similar on closely related host species. Results give the first evidence for lineage-specific bacterial associations to algal thalli. Furthermore, the results suggest that these algal species may control their epibiotic bacterial communities

Cellular senescence promotes progenitor cell expansion during axolotl limb regeneration

[EN] Axolotl limb regeneration is accompanied by the transient induction of cellular senescence within the blastema, the structure that nucleates regeneration. The precise role of this blastemal senescent cell (bSC) population, however, remains unknown. Here, through a combination of gain-and loss-of-function assays, we elucidate the functions and molecular features of cellular senescence in vivo. We demonstrate that cellular senescence plays a positive role during axolotl regeneration by creating a pro-proliferative niche that supports progenitor cell expansion and blastema outgrowth. Senescent cells impact their microenvironment via Wnt pathway modulation. Further, we identify a link between Wnt signaling and senescence induction and propose that bSC-derived Wnt signals facilitate the proliferation of neighboring cells in part by preventing their induction into senescence. This work defines the roles of cellular senescence in the regeneration of complex structures.We thank TUD-CMCB Flow Cytometry and Light Microscopy Facilities for cell sorting and imaging support; DRESDEN-concept genome center for RNA sequencing; MPI-CBG Computing Facility for image processing advice; Phillip Gates for technical support; Daniel Munoz Espin for nanoparticle advice; Gabriel Waksman for institutional support; Beate Gruhl, Anja Wagner, and Dominic Kruger for animal care; and all members of the Yun lab for advice and comments on the manuscript. This work was supported by an Alexander von Humboldt postdoctoral fellowship to H.E.W., a DAAD MSc scholarship (57507833) to D.L.-P., MISU-PROL funding from the FNRS (40005588) and Fondation Jaumotte-Demoulin funds to S.P.S., a CRTD E.V. scholarship to C.S.A., a DAAD Scholarship to K.E.T., CRTD-FSJ program funds to A.M.G., DFG (BU 2974/3-2 and EXC-2151-390873048) and Volkswagen Foundation Freigeist (A110720) grants to V.B., MCIU/AEI/FEDER, EU (PID2021-126304OB-C41 and PID2021-128141OB-C22) and Generatitat Valenciana (CIPROM/2021/007) grants to R.M.-M., and DFG (22137416, 450807335, and 497658823) grants and TUD and CRTD funds to M.H.Y.Yu, Q.; Walters, HE.; Pasquini, G.; Singh, SP.; Lachnit, M.; Oliveira, CR.; León-Periñán, D.... (2023). Cellular senescence promotes progenitor cell expansion during axolotl limb regeneration. Developmental Cell. 58(22):2416-2427. https://doi.org/10.1016/j.devcel.2023.09.00924162427582

Stability of proICA512/IA-2 and its targeting to insulin secretory granules require β4-sheet-mediated dimerization of its ectodomain in the endoplasmic reticulum

The type 1 diabetes autoantigen ICA512/IA-2/RPTPN is a receptor protein tyrosine phosphatase of the insulin secretory granules (SGs) which regulates the size of granule stores, possibly via cleavage/signaling of its cytosolic tail. The role of its extracellular region remains unknown. Structural studies indicated that β2- or β4-strands in the mature ectodomain (ME ICA512) form dimers in vitro. Here we show that ME ICA512 prompts proICA512 dimerization in the endoplasmic reticulum. Perturbation of ME ICA512 β2-strand N-glycosylation upon S508A replacement allows for proICA512 dimerization, O-glycosylation, targeting to granules, and conversion, which are instead precluded upon G553D replacement in the ME ICA512 β4-strand. S508A/G553D and N506A/G553D double mutants dimerize but remain in the endoplasmic reticulum. Removal of the N-terminal fragment (ICA512-NTF) preceding ME ICA512 allows an ICA512-ΔNTF G553D mutant to exit the endoplasmic reticulum, and ICA512-ΔNTF is constitutively delivered to the cell surface. The signal for SG sorting is located within the NTF RESP18 homology domain (RESP18-HD), whereas soluble NTF is retained in the endoplasmic reticulum. Hence, we propose that the ME ICA512 β2-strand fosters proICA512 dimerization until NTF prevents N506 glycosylation. Removal of this constraint allows for proICA512 β4-strand-induced dimerization, exit from the endoplasmic reticulum, O-glycosylation, and RESP18-HD-mediated targeting to granules.Fil: Torkko, Juha M.. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; Alemania. German Center for Diabetes Research; AlemaniaFil: Primo, Maria Evangelina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Dirkx, Ronald. German Center for Diabetes Research; Alemania. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; AlemaniaFil: Friedrich, Anne. German Center for Diabetes Research; Alemania. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; AlemaniaFil: Viehrig, Antje. German Center for Diabetes Research; Alemania. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; AlemaniaFil: Vergari, Elisa. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; Alemania. German Center for Diabetes Research; AlemaniaFil: Borgonovo, Barbara. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; Alemania. Max Planck Institute of Molecular Cell Biology and Genetics; AlemaniaFil: Sönmez, Anke. German Center for Diabetes Research; Alemania. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; AlemaniaFil: Wegbrod, Carolin. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; Alemania. German Center for Diabetes Research; AlemaniaFil: Lachnit, Martina. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; Alemania. German Center for Diabetes Research; AlemaniaFil: Münster, Carla. German Center for Diabetes Research; Alemania. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; AlemaniaFil: Sica, Mauricio Pablo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Ermacora, Mario Roberto. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Solimena, Michele. Max Planck Institute of Molecular Cell Biology and Genetics; Alemania. Uniklinikum Carl Gustav Carus. Paul Langerhans Institute Dresden; Alemania. German Center for Diabetes Research; Alemani

Reversão do efeito facilitatório da MT3 intra-hipocampal pré-teste com a administração do inibidor de transcrição gênica DRB imediatamente após o treino da tarefa de esquiva inibitória

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Reversão do efeito facilitatório da MT3 intra-hipocampal pré-teste com a administração do inibidor de transcrição gênica DRB imediatamente após o treino da tarefa de esquiva inibitória

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