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Szodorai E, Hevesi Z, Wagner L, Hökfelt TGM, Harkany T, Schnell R. A hydrophobic groove in secretagogin allows for alternate interactions with SNAP-25 and syntaxin-4 in endocrine tissues. Proc Natl Acad Sci U S A 2024; 121:e2309211121. [PMID: 38593081 PMCID: PMC11032447 DOI: 10.1073/pnas.2309211121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 03/09/2024] [Indexed: 04/11/2024] Open
Abstract
Vesicular release of neurotransmitters and hormones relies on the dynamic assembly of the exocytosis/trans-SNARE complex through sequential interactions of synaptobrevins, syntaxins, and SNAP-25. Despite SNARE-mediated release being fundamental for intercellular communication in all excitable tissues, the role of auxiliary proteins modulating the import of reserve vesicles to the active zone, and thus, scaling repetitive exocytosis remains less explored. Secretagogin is a Ca2+-sensor protein with SNAP-25 being its only known interacting partner. SNAP-25 anchors readily releasable vesicles within the active zone, thus being instrumental for 1st phase release. However, genetic deletion of secretagogin impedes 2nd phase release instead, calling for the existence of alternative protein-protein interactions. Here, we screened the secretagogin interactome in the brain and pancreas, and found syntaxin-4 grossly overrepresented. Ca2+-loaded secretagogin interacted with syntaxin-4 at nanomolar affinity and 1:1 stoichiometry. Crystal structures of the protein complexes revealed a hydrophobic groove in secretagogin for the binding of syntaxin-4. This groove was also used to bind SNAP-25. In mixtures of equimolar recombinant proteins, SNAP-25 was sequestered by secretagogin in competition with syntaxin-4. Kd differences suggested that secretagogin could shape unidirectional vesicle movement by sequential interactions, a hypothesis supported by in vitro biological data. This mechanism could facilitate the movement of transport vesicles toward release sites, particularly in the endocrine pancreas where secretagogin, SNAP-25, and syntaxin-4 coexist in both α- and β-cells. Thus, secretagogin could modulate the pace and fidelity of vesicular hormone release by differential protein interactions.
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Affiliation(s)
- Edit Szodorai
- Division of Molecular and Cellular Neuroendocrinology, Department of Neuroscience, Biomedicum 7D, Karolinska Institutet, SolnaSE-17165, Sweden
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, ViennaA-1090, Austria
| | - Zsofia Hevesi
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, ViennaA-1090, Austria
| | - Ludwig Wagner
- Department of Internal Medicine III, Medical University of Vienna, ViennaA-1090, Austria
| | - Tomas G. M. Hökfelt
- Division of Molecular and Cellular Neuroendocrinology, Department of Neuroscience, Biomedicum 7D, Karolinska Institutet, SolnaSE-17165, Sweden
| | - Tibor Harkany
- Division of Molecular and Cellular Neuroendocrinology, Department of Neuroscience, Biomedicum 7D, Karolinska Institutet, SolnaSE-17165, Sweden
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, ViennaA-1090, Austria
| | - Robert Schnell
- Division of Molecular and Cellular Neuroendocrinology, Department of Neuroscience, Biomedicum 7D, Karolinska Institutet, SolnaSE-17165, Sweden
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Alur V, Raju V, Vastrad B, Vastrad C, Kavatagimath S, Kotturshetti S. Bioinformatics Analysis of Next Generation Sequencing Data Identifies Molecular Biomarkers Associated With Type 2 Diabetes Mellitus. Clin Med Insights Endocrinol Diabetes 2023; 16:11795514231155635. [PMID: 36844983 PMCID: PMC9944228 DOI: 10.1177/11795514231155635] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 01/19/2023] [Indexed: 02/23/2023] Open
Abstract
Background Type 2 diabetes mellitus (T2DM) is the most common metabolic disorder. The aim of the present investigation was to identify gene signature specific to T2DM. Methods The next generation sequencing (NGS) dataset GSE81608 was retrieved from the gene expression omnibus (GEO) database and analyzed to identify the differentially expressed genes (DEGs) between T2DM and normal controls. Then, Gene Ontology (GO) and pathway enrichment analysis, protein-protein interaction (PPI) network, modules, miRNA (micro RNA)-hub gene regulatory network construction and TF (transcription factor)-hub gene regulatory network construction, and topological analysis were performed. Receiver operating characteristic curve (ROC) analysis was also performed to verify the prognostic value of hub genes. Results A total of 927 DEGs (461 were up regulated and 466 down regulated genes) were identified in T2DM. GO and REACTOME results showed that DEGs mainly enriched in protein metabolic process, establishment of localization, metabolism of proteins, and metabolism. The top centrality hub genes APP, MYH9, TCTN2, USP7, SYNPO, GRB2, HSP90AB1, UBC, HSPA5, and SQSTM1 were screened out as the critical genes. ROC analysis provides prognostic value of hub genes. Conclusion The potential crucial genes, especially APP, MYH9, TCTN2, USP7, SYNPO, GRB2, HSP90AB1, UBC, HSPA5, and SQSTM1, might be linked with risk of T2DM. Our study provided novel insights of T2DM into genetics, molecular pathogenesis, and novel therapeutic targets.
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Affiliation(s)
- Varun Alur
- Department of Endocrinology, J.J.M
Medical College, Davanagere, Karnataka, India
| | - Varshita Raju
- Department of Obstetrics and
Gynecology, J.J.M Medical College, Davanagere, Karnataka, India
| | - Basavaraj Vastrad
- Department of Pharmaceutical Chemistry,
K.L.E. College of Pharmacy, Gadag, Karnataka, India
| | | | - Satish Kavatagimath
- Department of Pharmacognosy, K.L.E.
College of Pharmacy, Belagavi, Karnataka, India
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3
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SCGN deficiency is a risk factor for autism spectrum disorder. Signal Transduct Target Ther 2023; 8:3. [PMID: 36588101 PMCID: PMC9806109 DOI: 10.1038/s41392-022-01225-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 09/15/2022] [Accepted: 09/30/2022] [Indexed: 01/03/2023] Open
Abstract
Autism spectrum disorder (ASD) affects 1-2% of all children and poses a great social and economic challenge for the globe. As a highly heterogeneous neurodevelopmental disorder, the development of its treatment is extremely challenging. Multiple pathways have been linked to the pathogenesis of ASD, including signaling involved in synaptic function, oxytocinergic activities, immune homeostasis, chromatin modifications, and mitochondrial functions. Here, we identify secretagogin (SCGN), a regulator of synaptic transmission, as a new risk gene for ASD. Two heterozygous loss-of-function mutations in SCGN are presented in ASD probands. Deletion of Scgn in zebrafish or mice leads to autism-like behaviors and impairs brain development. Mechanistically, Scgn deficiency disrupts the oxytocin signaling and abnormally activates inflammation in both animal models. Both ASD probands carrying Scgn mutations also show reduced oxytocin levels. Importantly, we demonstrate that the administration of oxytocin and anti-inflammatory drugs can attenuate ASD-associated defects caused by SCGN deficiency. Altogether, we identify a convergence between a potential autism genetic risk factor SCGN, and the pathological deregulation in oxytocinergic signaling and immune responses, providing potential treatment for ASD patients suffering from SCGN deficiency. Our study also indicates that it is critical to identify and stratify ASD patient populations based on their disease mechanisms, which could greatly enhance therapeutic success.
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Chidananda AH, Khandelwal R, Jhamkhindikar A, Pawar AD, Sharma AK, Sharma Y. Secretagogin is a Ca 2+-dependent stress-responsive chaperone that may also play a role in aggregation-based proteinopathies. J Biol Chem 2022; 298:102285. [PMID: 35870554 PMCID: PMC9425029 DOI: 10.1016/j.jbc.2022.102285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 11/17/2022] Open
Abstract
Secretagogin (SCGN) is a three-domain hexa-EF-hand Ca2+-binding protein that plays a regulatory role in the release of several hormones. SCGN is expressed largely in pancreatic β-cells, certain parts of the brain, and also in neuroendocrine tissues. The expression of SCGN is altered in several diseases, such as diabetes, cancers, and neurodegenerative disorders; however, the precise associations that closely link SCGN expression to such pathophysiologies are not known. In this work, we report that SCGN is an early responder to cellular stress, and SCGN expression is temporally upregulated by oxidative stress and heat shock. We show the overexpression of SCGN efficiently prevents cells from heat shock and oxidative damage. We further demonstrate that in the presence of Ca2+, SCGN efficiently prevents the aggregation of a broad range of model proteins in vitro. Small-angle X-ray scattering (BioSAXS) studies further reveal that Ca2+ induces the conversion of a closed compact apo-SCGN conformation into an open extended holo-SCGN conformation via multistate intermediates, consistent with the augmentation of chaperone activity of SCGN. Furthermore, isothermal titration calorimetry establishes that Ca2+ enables SCGN to bind α-synuclein and insulin, two target proteins of SCGN. Altogether, our data not only demonstrate that SCGN is a Ca2+-dependent generic molecular chaperone involved in protein homeostasis with broad substrate specificity but also elucidate the origin of its altered expression in several cancers. We describe a plausible mechanism of how perturbations in Ca2+ homeostasis and/or deregulated SCGN expression would hasten the process of protein misfolding, which is a feature of many aggregation-based proteinopathies.
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Affiliation(s)
- Amrutha H Chidananda
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad-500 007, India
| | - Radhika Khandelwal
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad-500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Aditya Jhamkhindikar
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad-500 007, India
| | - Asmita D Pawar
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad-500 007, India; Indian Institute of Scientific and Education Research (IISER), Berhampur-760010, India
| | - Anand K Sharma
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad-500 007, India.
| | - Yogendra Sharma
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad-500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India; Indian Institute of Scientific and Education Research (IISER), Berhampur-760010, India.
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5
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Mitra S, Basu S, Singh O, Srivastava A, Singru PS. Calcium-binding proteins typify the dopaminergic neuronal subtypes in the ventral tegmental area of zebra finch, Taeniopygia guttata. J Comp Neurol 2022; 530:2562-2586. [PMID: 35715989 DOI: 10.1002/cne.25352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 05/09/2022] [Accepted: 05/11/2022] [Indexed: 11/11/2022]
Abstract
Calcium-binding proteins (CBPs) regulate neuronal function in midbrain dopamine (DA)-ergic neurons in mammals by buffering and sensing the intracellular Ca2+ , and vesicular release. In birds, the equivalent set of neurons are important in song learning, directed singing, courtship, and energy balance, yet the status of CBPs in these neurons is unknown. Herein, for the first time, we probe the nature of CBPs, namely, Calbindin-, Calretinin-, Parvalbumin-, and Secretagogin-expressing DA neurons in the ventral tegmental area (VTA) and substantia nigra (SN) in the midbrain of zebra finch, Taeniopygia guttata. qRT-PCR analysis of ventral midbrain tissue fragment revealed higher Calbindin- and Calretinin-mRNA levels compared to Parvalbumin and Secretagogin. Application of immunofluorescence showed CBP-immunoreactive (-i) neurons in VTA (anterior [VTAa], mid [VTAm], caudal [VTAc]), SN (compacta [SNc], and reticulata [SNr]). Compared to VTAa, higher Calbindin- and Parvalbumin-immunoreactivity (-ir), and lower Calretinin-ir were observed in VTAm and VTAc. Secretagogin-ir was highly localized to VTAa. In SN, Calbindin- and Calretinin-ir were higher in SNc, SNr was Parvalbumin enriched, and Secretagogin-ir was not detected. Weak, moderate, and intense tyrosine hydroxylase (TH)-i VTA neurons were demarcated as subtypes 1, 2, and 3, respectively. While subtype 1 TH-i neurons were neither Calbindin- nor Calretinin-i, ∼80 and ∼65% subtype 2 and ∼30 and ∼45% subtype 3 TH-i neurons co-expressed Calbindin and Calretinin, respectively. All TH-i neuronal subtypes co-expressed Parvalbumin with reciprocal relationship with TH-ir. We suggest that the CBPs may determine VTA DA neuronal heterogeneity and differentially regulate their activity in T. guttata.
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Affiliation(s)
- Saptarsi Mitra
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Sumela Basu
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Omprakash Singh
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Abhinav Srivastava
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Praful S Singru
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
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6
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Basu S, Mitra S, Singh O, Chandramohan B, Singru PS. Secretagogin in the brain and pituitary of the catfish, Clarias batrachus: Molecular characterization and regulation by insulin. J Comp Neurol 2022; 530:1743-1772. [PMID: 35322425 DOI: 10.1002/cne.25311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 02/02/2022] [Accepted: 02/04/2022] [Indexed: 11/12/2022]
Abstract
Secretagogin (scgn), is a novel hexa EF-hand, phylogenetically conserved calcium-binding protein. It serves as Ca2+ sensor and participates in Ca2+ -signaling and neuroendocrine regulation in mammals. However, its relevance in the brain of non-mammalian vertebrates has largely remained unexplored. To address this issue, we studied the cDNA encoding scgn, scgn mRNA expression, and distribution of scgn-equipped elements in the brain and pituitary of a teleost, Clarias batrachus (cb). The cbscgn cDNA consists of three transcripts (T) variants: T1 (2185 bp), T2 (2151 bp) and T3 (2060 bp). While 816 bp ORF in T1 and T2 encodes highly conserved six EF-hand 272 aa protein fully capable of Ca2+ -binding, 726-bp ORF in T3 encodes 242 aa protein. The T1 showed >90% and >70% identity with scgn of catfishes, and other teleosts and mammals, respectively. The T1-mRNA was widely expressed in the brain and pituitary, while the expression of T3 was restricted to the telencephalon. Application of the anti-scgn antiserum revealed a ∼32 kDa scgn-immunoreactive (scgn-i) band (known molecular weight of scgn) in the forebrain tissue, and immunohistochemically labeled neurons in the olfactory epithelium and bulb, telencephalon, preoptic area, hypothalamus, thalamus, and hindbrain. In the pituitary, scgn-i cells were seen in the pars distalis and intermedia. Insulin is reported to regulate scgn mRNA in the mammalian hippocampus, and feeding-related neuropeptides in the telencephalon of teleost. Intracranial injection of insulin significantly increased T1-mRNA expression and scgn-immunoreactivity in the telencephalon. We suggest that scgn may be an important player in the regulation of olfactory, neuroendocrine system, and energy balance functions in C. batrachus.
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Affiliation(s)
- Sumela Basu
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Saptarsi Mitra
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Omprakash Singh
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
| | - Bathrachalam Chandramohan
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India
| | - Praful S Singru
- School of Biological Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, India.,Homi Bhabha National Institute (HBNI), Mumbai, India
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7
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Gilvesy A, Husen E, Magloczky Z, Mihaly O, Hortobágyi T, Kanatani S, Heinsen H, Renier N, Hökfelt T, Mulder J, Uhlen M, Kovacs GG, Adori C. Spatiotemporal characterization of cellular tau pathology in the human locus coeruleus-pericoerulear complex by three-dimensional imaging. Acta Neuropathol 2022; 144:651-676. [PMID: 36040521 PMCID: PMC9468059 DOI: 10.1007/s00401-022-02477-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 01/28/2023]
Abstract
Tau pathology of the noradrenergic locus coeruleus (LC) is a hallmark of several age-related neurodegenerative disorders, including Alzheimer's disease. However, a comprehensive neuropathological examination of the LC is difficult due to its small size and rod-like shape. To investigate the LC cytoarchitecture and tau cytoskeletal pathology in relation to possible propagation patterns of disease-associated tau in an unprecedented large-scale three-dimensional view, we utilized volume immunostaining and optical clearing technology combined with light sheet fluorescence microscopy. We examined AT8+ pathological tau in the LC/pericoerulear region of 20 brains from Braak neurofibrillary tangle (NFT) stage 0-6. We demonstrate an intriguing morphological complexity and heterogeneity of AT8+ cellular structures in the LC, representing various intracellular stages of NFT maturation and their diverse transition forms. We describe novel morphologies of neuronal tau pathology such as AT8+ cells with fine filamentous somatic protrusions or with disintegrating soma. We show that gradual dendritic atrophy is the first morphological sign of the degeneration of tangle-bearing neurons, even preceding axonal lesions. Interestingly, irrespective of the Braak NFT stage, tau pathology is more advanced in the dorsal LC that preferentially projects to vulnerable forebrain regions in Alzheimer's disease, like the hippocampus or neocortical areas, compared to the ventral LC projecting to the cerebellum and medulla. Moreover, already in the precortical Braak 0 stage, 3D analysis reveals clustering tendency and dendro-dendritic close appositions of AT8+ LC neurons, AT8+ long axons of NFT-bearing cells that join the ascending dorsal noradrenergic bundle after leaving the LC, as well as AT8+ processes of NFT-bearing LC neurons that target the 4th ventricle wall. Our study suggests that the unique cytoarchitecture, comprised of a densely packed and dendritically extensively interconnected neuronal network with long projections, makes the human LC to be an ideal anatomical template for early accumulation and trans-neuronal spreading of hyperphosphorylated tau.
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Affiliation(s)
- Abris Gilvesy
- Department of Neuroscience, Karolinska Institutet, Solnavägen 9, 17177, Stockholm, Sweden
- McGill University, Montreal, QC, H3A 0G4, Canada
| | - Evelina Husen
- Department of Neuroscience, Karolinska Institutet, Solnavägen 9, 17177, Stockholm, Sweden
| | - Zsofia Magloczky
- Human Brain Research Laboratory, Institute of Experimental Medicine, ELKH, Budapest, Hungary
| | - Orsolya Mihaly
- Department of Pathology, St. Borbála Hospital, Tatabánya, Hungary
| | - Tibor Hortobágyi
- Department of Neurology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Old Age Psychiatry, Institute of Psychiatry Psychology and Neuroscience, King's College London, London, UK
- Centre for Age-Related Medicine, SESAM, Stavanger University Hospital, Stavanger, Norway
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Shigeaki Kanatani
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Helmut Heinsen
- Clinic of Psychiatry and Institute of Forensic Pathology, University of Würzburg, 97080, Würzburg, Germany
- LIM-44, University of Sao Paulo Medical School, Sao Paulo, Brazil
| | - Nicolas Renier
- Sorbonne Université, Paris Brain Institute-ICM, INSERM, CNRS, AP-HP, Hôpital de la Pitié Salpêtrière, 75013, Paris, France
| | - Tomas Hökfelt
- Department of Neuroscience, Karolinska Institutet, Solnavägen 9, 17177, Stockholm, Sweden
| | - Jan Mulder
- Department of Neuroscience, Karolinska Institutet, Solnavägen 9, 17177, Stockholm, Sweden
| | - Mathias Uhlen
- Department of Neuroscience, Karolinska Institutet, Solnavägen 9, 17177, Stockholm, Sweden
- Science for Life Laboratory, Royal Institute of Technology, 10691, Stockholm, Sweden
| | - Gabor G Kovacs
- Tanz Centre for Research in Neurodegenerative Disease and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Laboratory Medicine Program and Krembil Brain Institute, University Health Network, Toronto, ON, Canada
| | - Csaba Adori
- Department of Neuroscience, Karolinska Institutet, Solnavägen 9, 17177, Stockholm, Sweden.
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8
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Khandelwal R, Sharma AK, Biswa BB, Sharma Y. Extracellular Secretagogin is internalized into the cells through endocytosis. FEBS J 2021; 289:3183-3204. [PMID: 34967502 DOI: 10.1111/febs.16338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 11/29/2022]
Abstract
Secretagogin (SCGN) is a calcium-sensor protein with a regulatory role in glucose metabolism and the secretion of several peptide hormones. Many, but not all, functions of SCGN can be explained by its intracellular manifestation. Despite early data on SCGN secretion, the secretory mechanism, biological fate, physiological implications, and trans-cellular signaling of extracellular SCGN remain unknown. We here report that extracellular SCGN is readily internalized into the C2C12 cells in an energy-dependent manner. Using endocytosis inhibitors, we demonstrate that SCGN internalizes via clathrin-mediated endocytosis, following which, SCGN localizes largely in the cytosol. Exogenous SCGN treatment induces a global proteomic reprogramming in C2C12 cells. Gene ontology search suggests that SCGN-induced proteomic reprogramming favors protein synthesis and cellular growth. We thus validated the cell proliferative action of SCGN using C2C12, HepG2, and NIH-3T3 cell lines. Based on the data, we propose that circulatory SCGN is internalized into the target cells and modulates the expression of cell growth-related proteins. The work suggests that extracellular SCGN is a functional protein, which communicates with specific cell types and directly modulates cell proliferation.
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Affiliation(s)
- Radhika Khandelwal
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad, 500 007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Anand Kumar Sharma
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad, 500 007, India
| | - Bhim B Biswa
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad, 500 007, India
| | - Yogendra Sharma
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad, 500 007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, India.,Indian Institute of Science Education and Research (IISER), Berhampur, Odisha, 760010, India
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9
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Kanu B, Kia GSN, Aimola IA, Korie GC, Tekki IS. Rabies virus infection is associated with alterations in the expression of parvalbumin and secretagogin in mice brain. Metab Brain Dis 2021; 36:1267-1275. [PMID: 33783673 PMCID: PMC8008021 DOI: 10.1007/s11011-021-00717-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/14/2021] [Indexed: 12/21/2022]
Abstract
Infection with the deadly rabies virus (RABV) leads to alteration of cellular gene expression. The RABV, similar to other neurodegenerative diseases may be implicated in neuronal death due to an imbalance in Ca2+ homeostasis. Parvalbumin (PV) and Secretagogin (Scgn), two members of the Calcium-Binding Proteins (CBPs) are useful neuronal markers responsible for calcium regulation and buffering with possible protective roles against infections. This study investigated whether infection with rabies virus causes variance in expression levels of PV and Scgn using the Challenge virus standard (CVS) and Nigerian Street Rabies virus (SRV) strains. Forty-eight, 4-week-old BALB/c mice strains were divided into two test groups and challenged with Rabies virus (RABV) infection and one control group. The presence of RABV antigen was verified by direct fluorescent antibody test (DFAT) and real-time quantitative PCR (qRT-PCR) was used to assess PV and Scgn gene expression. Infection with both virus strains resulted in significant (p < 0.05) increases in expression during early infection. Mid-infection phase caused reduced expression for both genes. However, as infection progressed to the terminal phase, a lower increase in expression was measured. Gene expression and viral load correlation indicated no positive relationship. Neurons with these CBPs may have a greater capacity to buffer calcium and be more resistant to degenerative changes caused by RABV. This implies that, when PV and Scgn expression levels are kept adequately high, the integrity of neurons may be maintained and degeneration caused by RABV infection may be prevented or stopped, hence, these are possible constituents of effective rabies therapy.
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Affiliation(s)
- Brenda Kanu
- Department of Biochemistry, Ahmadu Bello University, Zaria, Kaduna State, Nigeria.
- Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University Centre, Zaria, Kaduna State, Nigeria.
| | - Grace S N Kia
- Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University Centre, Zaria, Kaduna State, Nigeria
- Department of Veterinary Public Health, Ahmadu Bello University, Zaria, Kaduna State, Nigeria
| | - Idowu A Aimola
- Department of Biochemistry, Ahmadu Bello University, Zaria, Kaduna State, Nigeria
- Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University Centre, Zaria, Kaduna State, Nigeria
| | - George C Korie
- Department of Biochemistry, Ahmadu Bello University, Zaria, Kaduna State, Nigeria
- Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University Centre, Zaria, Kaduna State, Nigeria
| | - Ishaya S Tekki
- Central Diagnostics Laboratory, National Veterinary Research Institute, Vom, Plateau State, Nigeria
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10
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Sanders M, Petrasch-Parwez E, Habbes HW, Düring MV, Förster E. Postnatal Developmental Expression Profile Classifies the Indusium Griseum as a Distinct Subfield of the Hippocampal Formation. Front Cell Dev Biol 2021; 8:615571. [PMID: 33511122 PMCID: PMC7835525 DOI: 10.3389/fcell.2020.615571] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 12/07/2020] [Indexed: 11/13/2022] Open
Abstract
The indusium griseum (IG) is a cortical structure overlying the corpus callosum along its anterior–posterior extent. It has been classified either as a vestige of the hippocampus or as an extension of the dentate gyrus via the fasciola cinerea, but its attribution to a specific hippocampal subregion is still under debate. To specify the identity of IG neurons more precisely, we investigated the spatiotemporal expression of calbindin, secretagogin, Necab2, PCP4, and Prox1 in the postnatal mouse IG, fasciola cinerea, and hippocampus. We identified the calcium-binding protein Necab2 as a first reliable marker for the IG and fasciola cinerea throughout postnatal development into adulthood. In contrast, calbindin, secretagogin, and PCP4 were expressed each with a different individual time course during maturation, and at no time point, IG or fasciola cinerea principal neurons expressed Prox1, a transcription factor known to define dentate granule cell fate. Concordantly, in a transgenic mouse line expressing enhanced green fluorescent protein (eGFP) in dentate granule cells, neurons of IG and fasciola cinerea were eGFP-negative. Our findings preclude that IG neurons represent dentate granule cells, as earlier hypothesized, and strongly support the view that the IG is an own hippocampal subfield composed of a distinct neuronal population.
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Affiliation(s)
- Marie Sanders
- Department of Neuroanatomy and Molecular Brain Research, Ruhr-University Bochum, Bochum, Germany
| | | | - Hans-Werner Habbes
- Department of Neuroanatomy and Molecular Brain Research, Ruhr-University Bochum, Bochum, Germany
| | - Monika V Düring
- Department of Neuroanatomy and Molecular Brain Research, Ruhr-University Bochum, Bochum, Germany
| | - Eckart Förster
- Department of Neuroanatomy and Molecular Brain Research, Ruhr-University Bochum, Bochum, Germany
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Chondroitin sulfate proteoglycan-5 forms perisynaptic matrix assemblies in the adult rat cortex. Cell Signal 2020; 74:109710. [PMID: 32653642 DOI: 10.1016/j.cellsig.2020.109710] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 12/30/2022]
Abstract
Composition of the brain extracellular matrix changes in time as maturation proceeds. Chondroitin sulfate proteoglycan 5 (CSPG-5), also known as neuroglycan C, has been previously associated to differentiation since it shapes neurite growth and synapse forming. Here, we show that this proteoglycan persists in the postnatal rat brain, and its expression is higher in cortical regions with plastic properties, including hippocampus and the medial prefrontal cortex at the end of the second postnatal week. Progressively accumulating after birth, CSPG-5 typically concentrates around glutamatergic and GABAergic terminals in twelve-week old rat hippocampus. CSPG-5-containing perisynaptic matrix rings often appear at the peripheral margin of perineuronal nets. Electron microscopy and analysis of synaptosomal fraction showed that CSPG-5 accumulates around, and is associated to synapses, respectively. In vitro analyses suggest that neurons, but less so astrocytes, express CSPG-5 in rat primary neocortical cultures, and CSPG-5 produced by transfected neuroblastoma cells appear at endings and contact points of neurites. In human subjects, CSPG-5 expression shifts in brain areas of the default mode network of suicide victims, which may reflect an impact in the pathogenesis of psychiatric diseases or support diagnostic power.
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12
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Structural and mechanistic insights into secretagogin-mediated exocytosis. Proc Natl Acad Sci U S A 2020; 117:6559-6570. [PMID: 32156735 DOI: 10.1073/pnas.1919698117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Secretagogin (SCGN) is a hexa-EF-hand protein that is highly expressed in the pancreas, brain, and gastrointestinal tract. SCGN is known to modulate regulated exocytosis in multiple cell lines and tissues; however, its exact functions and underlying mechanisms remain unclear. Here, we report that SCGN interacts with the plasma membrane SNARE SNAP-25, but not the assembled SNARE complex, in a Ca2+-dependent manner. The crystal structure of SCGN in complex with a SNAP-25 fragment reveals that SNAP-25 adopts a helical structure and binds to EF-hands 5 and 6 of SCGN. SCGN strongly inhibits SNARE-mediated vesicle fusion in vitro by binding to SNAP-25. SCGN promotes the plasma membrane localization of SNAP-25, but not Syntaxin-1a, in SCGN-expressing cells. Finally, SCGN controls neuronal growth and brain development in zebrafish, likely via interacting with SNAP-25 or its close homolog, SNAP-23. Our results thus provide insights into the regulation of SNAREs and suggest that aberrant synapse functions underlie multiple neurological disorders caused by SCGN deficiency.
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Chidananda AH, Sharma AK, Khandelwal R, Sharma Y. Secretagogin Binding Prevents α-Synuclein Fibrillation. Biochemistry 2019; 58:4585-4589. [DOI: 10.1021/acs.biochem.9b00656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Amrutha H. Chidananda
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500007, India
| | - Anand Kumar Sharma
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500007, India
| | - Radhika Khandelwal
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Yogendra Sharma
- CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
- Indian Institute of Science Education and Research (IISER), Berhampur 760010, India
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