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Xu H, Zhang LB, Luo YY, Wang L, Zhang YP, Chen PQ, Ba XY, Han J, Luo H. Synaptotagmins family affect glucose transport in retinal pigment epithelial cells through their ubiquitination-mediated degradation and glucose transporter-1 regulation. World J Diabetes 2024; 15:958-976. [PMID: 38766439 PMCID: PMC11099358 DOI: 10.4239/wjd.v15.i5.958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/22/2024] [Accepted: 03/11/2024] [Indexed: 05/10/2024] Open
Abstract
BACKGROUND Synaptotagmins (SYTs) are a family of 17 membrane transporters that function as calcium ion sensors during the release of Ca2+-dependent neurotransmitters and hormones. However, few studies have reported whether members of the SYT family play a role in glucose uptake in diabetic retinopathy (DR) through Ca2+/glucose transporter-1 (GLUT1) and the possible regulatory mechanism of SYTs. AIM To elucidate the role of the SYT family in the regulation of glucose transport in retinal pigment epithelial cells and explore its potential as a therapeutic target for the clinical management of DR. METHODS DR was induced by streptozotocin in C57BL/6J mice and by high glucose medium in human retinal pigment epithelial cells (ARPE-19). Bioinformatics analysis, reverse transcriptase-polymerase chain reaction, Western blot, flow cytometry, ELISA, HE staining, and TUNEL staining were used for analysis. RESULTS Six differentially expressed proteins (SYT2, SYT3, SYT4, SYT7, SYT11, and SYT13) were found between the DR and control groups, and SYT4 was highly expressed. Hyperglycemia induces SYT4 overexpression, manipulates Ca2+ influx to induce GLUT1 fusion with the plasma membrane, promotes abnormal expression of the glucose transporter GLUT1 and excessive glucose uptake, induces ARPE-19 cell apoptosis, and promotes DR progression. Parkin deficiency inhibits the proteasomal degradation of SYT4 in DR, resulting in SYT4 accumulation and enhanced GLUT1 fusion with the plasma membrane, and these effects were blocked by oe-Parkin treatment. Moreover, dysregulation of the myelin transcription factor 1 (Myt1)-induced transcription of SYT4 in DR further activated the SYT4-mediated stimulus-secretion coupling process, and this process was inhibited in the oe-MYT1-treated group. CONCLUSION Our study reveals the key role of SYT4 in regulating glucose transport in retinal pigment epithelial cells during the pathogenesis of DR and the underlying mechanism and suggests potential therapeutic targets for clinical DR.
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Affiliation(s)
- Hong Xu
- Department of Ophthalmology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Li-Bo Zhang
- Department of Ophthalmology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Yi-Yi Luo
- Precision Medicine Center of Chuxiong Yi Autonomous Prefecture, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Ling Wang
- Department of Endocrinology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Ye-Pin Zhang
- Department of Pathology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Pei-Qi Chen
- Department of Endocrinology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Xue-Ying Ba
- Precision Medicine Center of Chuxiong Yi Autonomous Prefecture, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Jian Han
- Precision Medicine Center of Chuxiong Yi Autonomous Prefecture, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
| | - Heng Luo
- Department of Ophthalmology, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
- Precision Medicine Center of Chuxiong Yi Autonomous Prefecture, The People’s Hospital of Chuxiong Yi Autonomous Prefecture & The Fourth Affiliated Hospital of Dali University, Chuxiong Yi Autonomous Prefecture 675000, Yunnan Province, China
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Gao J, Zhang S, Deng P, Wu Z, Lemaitre B, Zhai Z, Guo Z. Dietary L-Glu sensing by enteroendocrine cells adjusts food intake via modulating gut PYY/NPF secretion. Nat Commun 2024; 15:3514. [PMID: 38664401 PMCID: PMC11045819 DOI: 10.1038/s41467-024-47465-4] [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: 02/09/2023] [Accepted: 03/28/2024] [Indexed: 04/28/2024] Open
Abstract
Amino acid availability is monitored by animals to adapt to their nutritional environment. Beyond gustatory receptors and systemic amino acid sensors, enteroendocrine cells (EECs) are believed to directly percept dietary amino acids and secrete regulatory peptides. However, the cellular machinery underlying amino acid-sensing by EECs and how EEC-derived hormones modulate feeding behavior remain elusive. Here, by developing tools to specifically manipulate EECs, we find that Drosophila neuropeptide F (NPF) from mated female EECs inhibits feeding, similar to human PYY. Mechanistically, dietary L-Glutamate acts through the metabotropic glutamate receptor mGluR to decelerate calcium oscillations in EECs, thereby causing reduced NPF secretion via dense-core vesicles. Furthermore, two dopaminergic enteric neurons expressing NPFR perceive EEC-derived NPF and relay an anorexigenic signal to the brain. Thus, our findings provide mechanistic insights into how EECs assess food quality and identify a conserved mode of action that explains how gut NPF/PYY modulates food intake.
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Affiliation(s)
- Junjun Gao
- Department of Medical Genetics, School of Basic Medicine, Institute for Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Song Zhang
- Department of Medical Genetics, School of Basic Medicine, Institute for Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Pan Deng
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, PR China
- Department of Mechanical Engineering, University of British Columbia, Vancouver, British Columbia, Canada
| | - Zhigang Wu
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, PR China
| | - Bruno Lemaitre
- Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Zongzhao Zhai
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, Hunan, PR China.
| | - Zheng Guo
- Department of Medical Genetics, School of Basic Medicine, Institute for Brain Research, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
- Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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Faggion S, Boschi E, Veroneze R, Carnier P, Bonfatti V. Genomic Prediction and Genome-Wide Association Study for Boar Taint Compounds. Animals (Basel) 2023; 13:2450. [PMID: 37570259 PMCID: PMC10417264 DOI: 10.3390/ani13152450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/13/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023] Open
Abstract
With a perspective future ban on surgical castration in Europe, selecting pigs with reduced ability to accumulate boar taint (BT) compounds (androstenone, indole, skatole) in their tissues seems a promising strategy. BT compound concentrations were quantified in the adipose tissue of 1075 boars genotyped at 29,844 SNPs. Traditional and SNP-based breeding values were estimated using pedigree-based BLUP (PBLUP) and genomic BLUP (GBLUP), respectively. Heritabilities for BT compounds were moderate (0.30-0.52). The accuracies of GBLUP and PBLUP were significantly different for androstenone (0.58 and 0.36, respectively), but comparable for indole and skatole (~0.43 and ~0.47, respectively). Several SNP windows, each explaining a small percentage of the variance of BT compound concentrations, were identified in a genome-wide association study (GWAS). A total of 18 candidate genes previously associated with BT (MX1), reproduction traits (TCF21, NME5, PTGFR, KCNQ1, UMODL1), and fat metabolism (CTSD, SYT8, TNNI2, CD81, EGR1, GIPC2, MIGA1, NEGR1, CCSER1, MTMR2, LPL, ERFE) were identified in the post-GWAS analysis. The large number of genes related to fat metabolism might be explained by the relationship between sexual steroid levels and fat deposition and be partially ascribed to the pig line investigated, which is selected for ham quality and not for lean growth.
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Affiliation(s)
- Sara Faggion
- Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell’Università 16, 35020 Padova, Italy; (E.B.); (P.C.); (V.B.)
| | - Elena Boschi
- Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell’Università 16, 35020 Padova, Italy; (E.B.); (P.C.); (V.B.)
| | - Renata Veroneze
- Department of Animal Science, Universidade Federal de Viçosa, Viçosa 36570-999, Brazil;
| | - Paolo Carnier
- Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell’Università 16, 35020 Padova, Italy; (E.B.); (P.C.); (V.B.)
| | - Valentina Bonfatti
- Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell’Università 16, 35020 Padova, Italy; (E.B.); (P.C.); (V.B.)
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Zhao X, Ma Y, Shi M, Huang M, Xin J, Ci S, Chen M, Jiang T, Hu Z, He L, Pan F, Guo Z. Excessive iron inhibits insulin secretion via perturbing transcriptional regulation of SYT7 by OGG1. Cell Mol Life Sci 2023; 80:159. [PMID: 37209177 PMCID: PMC11072990 DOI: 10.1007/s00018-023-04802-y] [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: 01/01/2023] [Revised: 05/08/2023] [Accepted: 05/08/2023] [Indexed: 05/22/2023]
Abstract
Although iron overload is closely related to the occurrence of type 2 diabetes mellitus (T2DM), the specific mechanism is unclear. Here, we found that excessive iron inhibited the secretion of insulin (INS) and impaired islet β cell function through downregulating Synaptotagmin 7 (SYT7) in iron overload model in vivo and in vitro. Our results further demonstrated that 8-oxoguanine DNA glycosylase (OGG1), a key protein in the DNA base excision repair, was an upstream regulator of SYT7. Interestingly, such regulation could be suppressed by excessive iron. Ogg1-null mice, iron overload mice and db/db mice exhibit reduced INS secretion, weakened β cell function and subsequently impaired glucose tolerance. Notably, SYT7 overexpression could rescue these phenotypes. Our data revealed an intrinsic mechanism by which excessive iron inhibits INS secretion through perturbing the transcriptional regulation of SYT7 by OGG1, which suggested that SYT7 was a potential target in clinical therapy for T2DM.
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Affiliation(s)
- Xingqi Zhao
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China
| | - Ying Ma
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China
| | - Munan Shi
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China
| | - Miaoling Huang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China
| | - Jingyu Xin
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China
| | - Shusheng Ci
- School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166, Jiangsu, China
| | - Meimei Chen
- Department of Endocrinology, The Second Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, 210000, Jiangsu, China
| | - Tao Jiang
- Department of Geriatrics, The Second Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, 210000, Jiangsu, China
| | - Zhigang Hu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China
| | - Lingfeng He
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China
| | - Feiyan Pan
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China.
| | - Zhigang Guo
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, 1 WenYuan Road, Nanjing, 210023, China.
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Lu H, Chen S, Nie Q, Xue Q, Fan H, Wang Y, Fan S, Zhu J, Shen H, Li H, Fang Q, Ni J, Chen G. Synaptotagmin-3 interactions with GluA2 mediate brain damage and impair functional recovery in stroke. Cell Rep 2023; 42:112233. [PMID: 36892998 DOI: 10.1016/j.celrep.2023.112233] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 01/20/2023] [Accepted: 02/23/2023] [Indexed: 03/10/2023] Open
Abstract
Synaptotagmin III (Syt3) is a Ca2+-dependent membrane-traffic protein that is highly concentrated in synaptic plasma membranes and affects synaptic plasticity by regulating post-synaptic receptor endocytosis. Here, we show that Syt3 is upregulated in the penumbra after ischemia/reperfusion (I/R) injury. Knockdown of Syt3 protects against I/R injury, promotes recovery of motor function, and inhibits cognitive decline. Overexpression of Syt3 exerts the opposite effects. Mechanistically, I/R injury augments Syt3-GluA2 interactions, decreases GluA2 surface expression, and promotes the formation of Ca2+-permeable AMPA receptors (CP-AMPARs). Using a CP-AMPAR antagonist or dissociating the Syt3-GluA2 complex via TAT-GluA2-3Y peptide promotes recovery from neurological impairments and improves cognitive function. Furthermore, Syt3 knockout mice are resistant to cerebral ischemia because they show high-level expression of surface GluA2 and low-level expression of CP-AMPARs after I/R. Our results indicate that Syt3-GluA2 interactions, which regulate the formation of CP-AMPARs, may be a therapeutic target for ischemic insults.
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Affiliation(s)
- Haifeng Lu
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Shujun Chen
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Qianqian Nie
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Qun Xue
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China.
| | - Hua Fan
- The First Affiliated Hospital, College of Clinical Medicine of Henan University of Science and Technology, Luoyang 471000, Henan, China
| | - Yiqing Wang
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Shenghao Fan
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Juehua Zhu
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Haitao Shen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Haiying Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Qi Fang
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Jianqiang Ni
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China
| | - Gang Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu, China; Institute of Stroke Research, Soochow University, Suzhou 215006, Jiangsu, China.
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Synaptotagmin 9 Modulates Spontaneous Neurotransmitter Release in Striatal Neurons by Regulating Substance P Secretion. J Neurosci 2023; 43:1475-1491. [PMID: 36732068 PMCID: PMC9992334 DOI: 10.1523/jneurosci.1857-22.2023] [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: 09/29/2022] [Revised: 01/05/2023] [Accepted: 01/10/2023] [Indexed: 02/04/2023] Open
Abstract
Synaptotagmin 9 (SYT9) is a tandem C2 domain Ca2+ sensor for exocytosis in neuroendocrine cells; its function in neurons remains unclear. Here, we show that, in mixed-sex cultures, SYT9 does not trigger rapid synaptic vesicle exocytosis in mouse cortical, hippocampal, or striatal neurons, unless it is massively overexpressed. In striatal neurons, loss of SYT9 reduced the frequency of spontaneous neurotransmitter release events (minis). We delved into the underlying mechanism and discovered that SYT9 was localized to dense-core vesicles that contain substance P (SP). Loss of SYT9 impaired SP release, causing the observed decrease in mini frequency. This model is further supported by loss of function mutants. Namely, Ca2+ binding to the C2A domain of SYT9 triggered membrane fusion in vitro, and mutations that disrupted this activity abolished the ability of SYT9 to regulate both SP release and mini frequency. We conclude that SYT9 indirectly regulates synaptic transmission in striatal neurons by controlling SP release.SIGNIFICANCE STATEMENT Synaptotagmin 9 (SYT9) has been described as a Ca2+ sensor for dense-core vesicle (DCV) exocytosis in neuroendocrine cells, but its role in neurons remains unclear, despite widespread expression in the brain. This article examines the role of SYT9 in synaptic transmission across cultured cortical, hippocampal, and striatal neuronal preparations. We found that SYT9 regulates spontaneous neurotransmitter release in striatal neurons by serving as a Ca2+ sensor for the release of the neuromodulator substance P from DCVs. This demonstrates a novel role for SYT9 in neurons and uncovers a new field of study into neuromodulation by SYT9, a protein that is widely expressed in the brain.
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Fujioka A, Nagano M, Ikegami K, Masumoto KH, Yoshikawa T, Koinuma S, Nakahama KI, Shigeyoshi Y. Circadian expression and specific localization of synaptotagmin17 in the suprachiasmatic nucleus, the master circadian oscillator in mammals. Brain Res 2023; 1798:148129. [PMID: 36332665 DOI: 10.1016/j.brainres.2022.148129] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/12/2022] [Accepted: 10/19/2022] [Indexed: 11/06/2022]
Abstract
The localization and function of synaptotagmin (syt)17 in the suprachiasmatic nucleus (SCN) of the brain, which is the master circadian oscillator, were investigated. The Syt17 mRNA-containing neurons were mainly situated in the shell region while SYT17 immunoreactive cell bodies and neural fibers were detected in the core and shell of the SCN and the subparaventricular zone (SPZ). Further, electron microscopy analysis revealed SYT17 in the rough endoplasmic reticulum (rER), Golgi apparatus (G), and large and small vesicles of neurons. Syt17 mRNA expression in the SCN showed a circadian rhythm, and light exposure at night suppressed its expression. In addition, the free running period of locomotor activity rhythm was shortened in Syt17-deletion mutant mice. These findings suggest that SYT17 is involved in the regulation of circadian rhythms.
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Affiliation(s)
- Atsuko Fujioka
- Department of Anatomy and Neurobiology, Kindai University, Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511, Japan
| | - Mamoru Nagano
- Department of Anatomy and Neurobiology, Kindai University, Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511, Japan
| | - Keisuke Ikegami
- Department of Anatomy and Neurobiology, Kindai University, Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511, Japan
| | - Koh-Hei Masumoto
- Department of Anatomy and Neurobiology, Kindai University, Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511, Japan
| | - Tomoko Yoshikawa
- Department of Anatomy and Neurobiology, Kindai University, Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511, Japan
| | - Satoshi Koinuma
- Department of Anatomy and Neurobiology, Kindai University, Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511, Japan
| | - Ken-Ichi Nakahama
- Department of Cellular Physiological Chemistry, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yasufumi Shigeyoshi
- Department of Anatomy and Neurobiology, Kindai University, Faculty of Medicine, 377-2 Ohnohigashi, Osakasayama, Osaka 589-8511, Japan.
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Ofori JK, Karagiannopoulos A, Barghouth M, Nagao M, Andersson ME, Salunkhe VA, Zhang E, Wendt A, Eliasson L. The highly expressed calcium-insensitive synaptotagmin-11 and synaptotagmin-13 modulate insulin secretion. Acta Physiol (Oxf) 2022; 236:e13857. [PMID: 35753051 PMCID: PMC9541707 DOI: 10.1111/apha.13857] [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: 12/08/2021] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 12/01/2022]
Abstract
AIM SYT11 and SYT13, two calcium-insensitive synaptotagmins, are downregulated in islets from type-2 diabetic donors, but their function in insulin secretion is unknown. To address this, we investigated the physiological role of these two synaptotagmins in insulin secreting cells. METHODS Correlations between gene expression levels were performed using previously described RNA-seq data on islets from 188 human donors. SiRNA knockdown was performed in EndoC-βH1 and INS-1 832/13 cells. Insulin secretion was measured with ELISA. Patch clamp was used for single cell electrophysiology. Confocal microscopy was used to determine intra-cellular localization. RESULTS Human islet expression of the transcription factor PDX-1 was positively correlated with SYT11 (p = 2.4e-10 ) and SYT13 (p<2.2 e-16 ). Syt11 and Syt13 both co-localized with insulin, indicating their localization in insulin granules. Downregulation of Syt11 in INS-1 832/13 cells (siSYT11) resulted in increased basal and glucose-induced insulin secretion. Downregulation of Syt13 (siSYT13) decreased insulin secretion induced by glucose and K+ .Interestingly, the cAMP raising agent forskolin was unable to enhance insulin secretion in siSYT13 cells. There was no difference in insulin content, exocytosis, or voltage-gated Ca2+ currents in the two models. Double knockdown of Syt11 and Syt13 (DKD) resembled the results in siSYT13 cells. CONCLUSION SYT11 and SYT13 have similar localization and transcriptional regulation but they regulate insulin secretion differentially. While downregulation of SYT11 might be a compensatory mechanism in type-2 diabetes, downregulation of SYT13 reduces the insulin secretory response and overrules the compensatory regulation of SYT11 in a way that could aggravate the disease.
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Affiliation(s)
- Jones K Ofori
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden
| | - Alexandros Karagiannopoulos
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden
| | - Mohammad Barghouth
- Islet Pathophysiology, Department of Clinical Sciences Malmö, Lund University, Diabetes Centre, Lund University, Malmö, Sweden
| | - Mototsugu Nagao
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden.,Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Markus E Andersson
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden
| | - Vishal A Salunkhe
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden.,Institute of Neuroscience and Physiology, Department of Physiology, Metabolism research unit, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Enming Zhang
- Islet Pathophysiology, Department of Clinical Sciences Malmö, Lund University, Diabetes Centre, Lund University, Malmö, Sweden
| | - Anna Wendt
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden
| | - Lena Eliasson
- Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden
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Tarquis-Medina M, Scheibner K, González-García I, Bastidas-Ponce A, Sterr M, Jaki J, Schirge S, García-Cáceres C, Lickert H, Bakhti M. Synaptotagmin-13 Is a Neuroendocrine Marker in Brain, Intestine and Pancreas. Int J Mol Sci 2021; 22:ijms222212526. [PMID: 34830411 PMCID: PMC8620464 DOI: 10.3390/ijms222212526] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 11/16/2022] Open
Abstract
Synaptotagmin-13 (Syt13) is an atypical member of the vesicle trafficking synaptotagmin protein family. The expression pattern and the biological function of this Ca2+-independent protein are not well resolved. Here, we have generated a novel Syt13-Venus fusion (Syt13-VF) fluorescence reporter allele to track and isolate tissues and cells expressing Syt13 protein. The reporter allele is regulated by endogenous cis-regulatory elements of Syt13 and the fusion protein follows an identical expression pattern of the endogenous Syt13 protein. The homozygous reporter mice are viable and fertile. We identify the expression of the Syt13-VF reporter in different regions of the brain with high expression in tyrosine hydroxylase (TH)-expressing and oxytocin-producing neuroendocrine cells. Moreover, Syt13-VF is highly restricted to all enteroendocrine cells in the adult intestine that can be traced in live imaging. Finally, Syt13-VF protein is expressed in the pancreatic endocrine lineage, allowing their specific isolation by flow sorting. These findings demonstrate high expression levels of Syt13 in the endocrine lineages in three major organs harboring these secretory cells. Collectively, the Syt13-VF reporter mouse line provides a unique and reliable tool to dissect the spatio-temporal expression pattern of Syt13 and enables isolation of Syt13-expressing cells that will aid in deciphering the molecular functions of this protein in the neuroendocrine system.
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Affiliation(s)
- Marta Tarquis-Medina
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; (M.T.-M.); (K.S.); (A.B.-P.); (M.S.); (J.J.); (S.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
- School of Medicine, Technische Universität München, 81675 München, Germany
| | - Katharina Scheibner
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; (M.T.-M.); (K.S.); (A.B.-P.); (M.S.); (J.J.); (S.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
| | - Ismael González-García
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Aimée Bastidas-Ponce
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; (M.T.-M.); (K.S.); (A.B.-P.); (M.S.); (J.J.); (S.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
| | - Michael Sterr
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; (M.T.-M.); (K.S.); (A.B.-P.); (M.S.); (J.J.); (S.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
| | - Jessica Jaki
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; (M.T.-M.); (K.S.); (A.B.-P.); (M.S.); (J.J.); (S.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
| | - Silvia Schirge
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; (M.T.-M.); (K.S.); (A.B.-P.); (M.S.); (J.J.); (S.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
| | - Cristina García-Cáceres
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, 85764 Neuherberg, Germany
- Medizinische Klinik and Poliklinik IV, Klinikum der Universität, Ludwig-Maximilians-Universität München, 80336 Munich, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; (M.T.-M.); (K.S.); (A.B.-P.); (M.S.); (J.J.); (S.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
- School of Medicine, Technische Universität München, 81675 München, Germany
- Correspondence: (H.L.); (M.B.)
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany; (M.T.-M.); (K.S.); (A.B.-P.); (M.S.); (J.J.); (S.S.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; (I.G.-G.); (C.G.-C.)
- Correspondence: (H.L.); (M.B.)
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10
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Yang MF, Long XX, Hu HS, Bin YL, Chen XM, Wu BH, Peng QZ, Wang LS, Yao J, Li DF. Comprehensive analysis on the expression profile and prognostic values of Synaptotagmins (SYTs) family members and their methylation levels in gastric cancer. Bioengineered 2021; 12:3550-3565. [PMID: 34229539 PMCID: PMC8806422 DOI: 10.1080/21655979.2021.1951059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Synaptotagmins (SYTs), constitute a family of 17 membrane-trafficking protein, palying crucial roles in the development and progression of human cancers. However, only very few studies have investigated the expression profile and prognostic values of SYTs family members in gastric cancer (GC). Therefore, we comprehensively evaluated the expression, methylation, prognosis and immune significance of SYTs family members through bioinformatics analysis from the online databases in GC. The expressions of SYT4, SYT9, and SYT14 were up-regulated, and negatively associated with their methylation levels in GC. Both the over-expression of SYT4, SYT9 and SYT14 and their hypomethylation levels contributed to an unsatisfactory overall survival (OS) and progression-free survival (PFS) in GC. Moreover, the low expressions of several methylation cg sites (cg02795029, cg07581146, cg15149095, cg19922137, cg25371503, cg26158959, cg02269161, cg03226737, cg08185661, cg16437728, cg22723056 and cg24678137) were significantly correlated with an unfavorable OS and PFS in GC. Furthermore, the expression of SYT4, SYT9 and SYT14 played a pivotal role in immune cells infiltration in GC. Collectively, our current finding suggested that SYT4, SYT9 and SYT14 might be potent prognostic indictors and promising immunotherapeutic targets for GC patients.
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Affiliation(s)
- Mei-Feng Yang
- Department of Hematology, Yantian District People's Hospital, Shenzhen, Guangdong, China
| | - Xing-Xing Long
- Department of Hematology, The First Affiliated Hospital of South China of University, South China of University, Hengyang, Hunan, China
| | - Hong-Sai Hu
- Department of Gastroenterology, The Affiliated Zhuzhou Hospital of Xiangya Medical College, Zhuzhou, Hunan, China
| | - Yu-Ling Bin
- Department of Gastroenterology, The Affiliated Zhuzhou Hospital of Xiangya Medical College, Zhuzhou, Hunan, China
| | - Xuan-Ming Chen
- Department of Gastroenterology, The First Affiliated Hospital of South China of University, South China of University, Hengyang, Hunan, China
| | - Ben-Hua Wu
- Department of Gastroenterology, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, China
| | - Quan-Zhou Peng
- Department of Pathology, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, China
| | - Li-Sheng Wang
- Department of Gastroenterology, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, China
| | - Jun Yao
- Department of Gastroenterology, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, China
| | - De-Feng Li
- Department of Gastroenterology, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, China
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11
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Function of Drosophila Synaptotagmins in membrane trafficking at synapses. Cell Mol Life Sci 2021; 78:4335-4364. [PMID: 33619613 PMCID: PMC8164606 DOI: 10.1007/s00018-021-03788-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/29/2021] [Accepted: 02/09/2021] [Indexed: 12/13/2022]
Abstract
The Synaptotagmin (SYT) family of proteins play key roles in regulating membrane trafficking at neuronal synapses. Using both Ca2+-dependent and Ca2+-independent interactions, several SYT isoforms participate in synchronous and asynchronous fusion of synaptic vesicles (SVs) while preventing spontaneous release that occurs in the absence of stimulation. Changes in the function or abundance of the SYT1 and SYT7 isoforms alter the number and route by which SVs fuse at nerve terminals. Several SYT family members also regulate trafficking of other subcellular organelles at synapses, including dense core vesicles (DCV), exosomes, and postsynaptic vesicles. Although SYTs are linked to trafficking of multiple classes of synaptic membrane compartments, how and when they interact with lipids, the SNARE machinery and other release effectors are still being elucidated. Given mutations in the SYT family cause disorders in both the central and peripheral nervous system in humans, ongoing efforts are defining how these proteins regulate vesicle trafficking within distinct neuronal compartments. Here, we review the Drosophila SYT family and examine their role in synaptic communication. Studies in this invertebrate model have revealed key similarities and several differences with the predicted activity of their mammalian counterparts. In addition, we highlight the remaining areas of uncertainty in the field and describe outstanding questions on how the SYT family regulates membrane trafficking at nerve terminals.
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12
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Sur A, Meyer NP. Resolving Transcriptional States and Predicting Lineages in the Annelid Capitella teleta Using Single-Cell RNAseq. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2020.618007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Evolution and diversification of cell types has contributed to animal evolution. However, gene regulatory mechanisms underlying cell fate acquisition during development remains largely uncharacterized in spiralians. Here we use a whole-organism, single-cell transcriptomic approach to map larval cell types in the annelid Capitella teleta at 24- and 48-h post gastrulation (stages 4 and 5). We identified eight unique cell clusters (undifferentiated precursors, ectoderm, muscle, ciliary-band, gut, neurons, neurosecretory cells, and protonephridia), thus helping to identify uncharacterized molecular signatures such as previously unknown neurosecretory cell markers in C. teleta. Analysis of coregulatory programs in individual clusters revealed gene interactions that can be used for comparisons of cell types across taxa. We examined the neural and neurosecretory clusters more deeply and characterized a differentiation trajectory starting from dividing precursors to neurons using Monocle3 and velocyto. Pseudotime analysis along this trajectory identified temporally-distinct cell states undergoing progressive gene expression changes over time. Our data revealed two potentially distinct neural differentiation trajectories including an early trajectory for brain neurosecretory cells. This work provides a valuable resource for future functional investigations to better understanding neurogenesis and the transitions from neural precursors to neurons in an annelid.
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13
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Li T, Hu J, Wang S, Zhang H. Super-variants identification for brain connectivity. Hum Brain Mapp 2020; 42:1304-1312. [PMID: 33236465 PMCID: PMC7927294 DOI: 10.1002/hbm.25294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/25/2020] [Accepted: 11/12/2020] [Indexed: 12/17/2022] Open
Abstract
Identifying genetic biomarkers for brain connectivity helps us understand genetic effects on brain function. The unique and important challenge in detecting associations between brain connectivity and genetic variants is that the phenotype is a matrix rather than a scalar. We study a new concept of super‐variant for genetic association detection. Similar to but different from the classic concept of gene, a super‐variant is a combination of alleles in multiple loci but contributing loci can be anywhere in the genome. We hypothesize that the super‐variants are easier to detect and more reliable to reproduce in their associations with brain connectivity. By applying a novel ranking and aggregation method to the UK Biobank databases, we discovered and verified several replicable super‐variants. Specifically, we investigate a discovery set with 16,421 subjects and a verification set with 2,882 subjects, where they are formed according to release date, and the verification set is used to validate the genetic associations from the discovery phase. We identified 12 replicable super‐variants on Chromosomes 1, 3, 7, 8, 9, 10, 12, 15, 16, 18, and 19. These verified super‐variants contain single nucleotide polymorphisms that locate in 14 genes which have been reported to have association with brain structure and function, and/or neurodevelopmental and neurodegenerative disorders in the literature. We also identified novel loci in genes RSPO2 and TMEM74 which may be upregulated in brain issues. These findings demonstrate the validity of the super‐variants and its capability of unifying existing results as well as discovering novel and replicable results.
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Affiliation(s)
- Ting Li
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
| | - Jianchang Hu
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
| | - Shiying Wang
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
| | - Heping Zhang
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
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14
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Guan Z, Quiñones-Frías MC, Akbergenova Y, Littleton JT. Drosophila Synaptotagmin 7 negatively regulates synaptic vesicle release and replenishment in a dosage-dependent manner. eLife 2020; 9:e55443. [PMID: 32343229 PMCID: PMC7224696 DOI: 10.7554/elife.55443] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 04/28/2020] [Indexed: 01/03/2023] Open
Abstract
Synchronous neurotransmitter release is triggered by Ca2+ binding to the synaptic vesicle protein Synaptotagmin 1, while asynchronous fusion and short-term facilitation is hypothesized to be mediated by plasma membrane-localized Synaptotagmin 7 (SYT7). We generated mutations in Drosophila Syt7 to determine if it plays a conserved role as the Ca2+ sensor for these processes. Electrophysiology and quantal imaging revealed evoked release was elevated 2-fold. Syt7 mutants also had a larger pool of readily-releasable vesicles, faster recovery following stimulation, and intact facilitation. Syt1/Syt7 double mutants displayed more release than Syt1 mutants alone, indicating SYT7 does not mediate the residual asynchronous release remaining in the absence of SYT1. SYT7 localizes to an internal membrane tubular network within the peri-active zone, but does not enrich at active zones. These findings indicate the two Ca2+ sensor model of SYT1 and SYT7 mediating all phases of neurotransmitter release and facilitation is not applicable at Drosophila synapses.
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Affiliation(s)
- Zhuo Guan
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Monica C Quiñones-Frías
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Yulia Akbergenova
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
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15
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Taiz L, Alkon D, Draguhn A, Murphy A, Blatt M, Thiel G, Robinson DG. Reply to Trewavas et al. and Calvo and Trewavas. TRENDS IN PLANT SCIENCE 2020; 25:218-220. [PMID: 31926764 DOI: 10.1016/j.tplants.2019.12.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 12/16/2019] [Indexed: 05/07/2023]
Affiliation(s)
- Lincoln Taiz
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
| | - Daniel Alkon
- Neurotrope, Inc., 1185 Avenue of the Americas, 3rd Floor, New York, NY 10036, USA
| | - Andreas Draguhn
- Institut für Physiologie und Pathophysiologie, Medizinische Fakultät Heidelberg, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany
| | - Angus Murphy
- Department of Plant Science and Landscape Architecture, 2104 Plant Sciences Building, College Park, MD 20742, USA
| | - Michael Blatt
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Gerhard Thiel
- Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 3, 64287 Darmstadt, Germany
| | - David G Robinson
- Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
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16
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Varga K, Jiang ZJ, Gong LW. Phosphatidylserine is critical for vesicle fission during clathrin-mediated endocytosis. J Neurochem 2019; 152:48-60. [PMID: 31587282 DOI: 10.1111/jnc.14886] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/25/2019] [Accepted: 10/01/2019] [Indexed: 12/11/2022]
Abstract
Phosphatidylserine (PS), a negatively charged phospholipid present predominantly at the inner leaflet of the plasma membrane, has been widely implicated in many cellular processes including membrane trafficking. Along this line, PS has been demonstrated to be important for endocytosis, however, the involved mechanisms remain uncertain. By monitoring clathrin-mediated endocytosis (CME) of single vesicles in mouse chromaffin cells using cell-attached capacitance measurements that offer millisecond time resolution, we demonstrate in the present study that the fission-pore duration is reduced by PS addition, indicating a stimulatory role of PS in regulating the dynamics of vesicle fission during CME. Furthermore, our results show that the PS-mediated effect on the fission-pore duration is Ca2+ -dependent and abolished in the absence of synaptotagmin 1 (Syt1), implying that Syt1 is necessary for the stimulatory role of PS in vesicle fission during CME. Consistently, a Syt1 mutant with a defective PS-Syt1 interaction increases the fission-pore duration. Taken together, our study suggests that PS-Syt1 interaction may be critical in regulating fission dynamics during CME.
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Affiliation(s)
- Kelly Varga
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.,Department of Biological Sciences, University of North Texas at Dallas, Dallas, Texas, USA
| | - Zhong-Jiao Jiang
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Liang-Wei Gong
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
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17
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König D, Dagenais P, Senk A, Djonov V, Aegerter CM, Jaźwińska A. Distribution and Restoration of Serotonin-Immunoreactive Paraneuronal Cells During Caudal Fin Regeneration in Zebrafish. Front Mol Neurosci 2019; 12:227. [PMID: 31616250 PMCID: PMC6763699 DOI: 10.3389/fnmol.2019.00227] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 09/04/2019] [Indexed: 12/22/2022] Open
Abstract
Aquatic vertebrates possess diverse types of sensory cells in their skin to detect stimuli in the water. In the adult zebrafish, a common model organism, the presence of such cells in fins has only rarely been studied. Here, we identified scattered serotonin (5-HT)-positive cells in the epidermis of the caudal fin. These cells were distinct from keratinocytes as revealed by their low immunoreactivity for cytokeratin and desmosome markers. Instead, they were detected by Calretinin (Calbindin-2) and Synaptic vesicle glycoprotein 2 (SV2) antibodies, indicating a calcium-regulated neurosecretory activity. Consistently, electron microscopy revealed abundant secretory organelles in desmosome-negative cells in the fin epidermis. Based on the markers, 5-HT, Calretinin and SV2, we referred to these cells as HCS-cells. We found that HCS-cells were spread throughout the entire caudal fin at an average density of 140 cells per mm2 on each fin surface. These cells were strongly enriched at ray bifurcations in wild type fins, as well as in elongated fins of another longfin mutant fish. To determine whether hydrodynamics play a role in the distribution of HCS-cells, we used an interdisciplinary approach and performed kinematic analysis. Measurements of particle velocity with a fin model revealed differences in fluid velocities between bifurcated rods and adjacent non-bifurcated regions. Therefore the accumulation of HCS-cells near bone bifurcations may be a biological adaptation for sensing of water parameters. The significance of this HCS-cell pattern is reinforced by the fact, that it is reestablished in the regenerated fin after amputation. Regeneration of HCS-cells was not impaired by the chemical inhibition of serotonin synthesis, suggesting that this neurotransmitter is not essential for the restorative process. In conclusion, our study identified a specific population of solitary paraneurons in the zebrafish fin, whose distribution correlates with fluid dynamics.
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Affiliation(s)
- Désirée König
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Paule Dagenais
- Physik-Institut, University of Zurich, Zurich, Switzerland
| | - Anita Senk
- Institute of Anatomy, University of Bern, Bern, Switzerland
| | | | | | - Anna Jaźwińska
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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18
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Rozov A, Bolshakov AP, Valiullina-Rakhmatullina F. The Ever-Growing Puzzle of Asynchronous Release. Front Cell Neurosci 2019; 13:28. [PMID: 30809127 PMCID: PMC6379310 DOI: 10.3389/fncel.2019.00028] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 01/22/2019] [Indexed: 11/13/2022] Open
Abstract
Invasion of an action potential (AP) to presynaptic terminals triggers calcium dependent vesicle fusion in a relatively short time window, about a millisecond, after the onset of the AP. This allows fast and precise information transfer from neuron to neuron by means of synaptic transmission and phasic mediator release. However, at some synapses a single AP or a short burst of APs can generate delayed or asynchronous synaptic release lasting for tens or hundreds of milliseconds. Understanding the mechanisms underlying asynchronous release (AR) is important, since AR can better recruit extrasynaptic metabotropic receptors and maintain a high level of neurotransmitter in the extracellular space for a substantially longer period of time after presynaptic activity. Over the last decade substantial work has been done to identify the presynaptic calcium sensor that may be involved in AR. Several models have been suggested which may explain the long lasting presynaptic calcium elevation a prerequisite for prolonged delayed release. However, the presynaptic mechanisms underlying asynchronous vesicle release are still not well understood. In this review article, we provide an overview of the current state of knowledge on the molecular components involved in delayed vesicle fusion and in the maintenance of sufficient calcium concentration to trigger AR. In addition, we discuss possible alternative models that may explain intraterminal calcium dynamics underlying AR.
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Affiliation(s)
- Andrei Rozov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia.,Department of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Alexey P Bolshakov
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences (RAS), Moscow, Russia.,Laboratory of Electrophysiology, Pirogov Russian National Research Medical University, Moscow, Russia
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19
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Tran HT, Anderson LH, Knight JD. Membrane-Binding Cooperativity and Coinsertion by C2AB Tandem Domains of Synaptotagmins 1 and 7. Biophys J 2019; 116:1025-1036. [PMID: 30795874 DOI: 10.1016/j.bpj.2019.01.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 12/21/2018] [Accepted: 01/30/2019] [Indexed: 02/04/2023] Open
Abstract
Synaptotagmin-1 (Syt-1) and synaptotagmin-7 (Syt-7) contain analogous tandem C2 domains, C2A and C2B, which together sense Ca2+ to bind membranes and promote the stabilization of exocytotic fusion pores. Syt-1 triggers fast release of neurotransmitters, whereas Syt-7 functions in processes that involve lower Ca2+ concentrations such as hormone secretion. Syt-1 C2 domains are reported to bind membranes cooperatively, based on the observation that they penetrate farther into membranes as the C2AB tandem than as individual C2 domains. In contrast, we previously suggested that the two C2 domains of Syt-7 bind membranes independently, based in part on measurements of their liposome dissociation kinetics. Here, we investigated C2A-C2B interdomain cooperativity with Syt-1 and Syt-7 using directly comparable measurements. Equilibrium Ca2+ titrations demonstrate that the Syt-7 C2AB tandem binds liposomes lacking phosphatidylinositol-4,5-bisphosphate (PIP2) with greater Ca2+ sensitivity than either of its individual domains and binds to membranes containing PIP2 even in the absence of Ca2+. Stopped-flow kinetic measurements show differences in cooperativity between Syt-1 and Syt-7: Syt-1 C2AB dissociates from PIP2-free liposomes much more slowly than either of its individual C2 domains, indicating cooperativity, whereas the major population of Syt-7 C2AB has a dissociation rate comparable to its C2A domain, suggesting a lack of cooperativity. A minor subpopulation of Syt-7 C2AB dissociates at a slower rate, which could be due to a small cooperative component and/or liposome clustering. Measurements using an environment-sensitive fluorescent probe indicate that the Syt-7 C2B domain inserts deeply into membranes as part of the C2AB tandem, similar to the coinsertion previously reported for Syt-1. Overall, coinsertion of C2A and C2B domains is coupled to cooperative energetic effects in Syt-1 to a much greater extent than in Syt-7. The difference can be understood in terms of the relative contributions of C2A and C2B domains toward membrane binding in the two proteins.
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Affiliation(s)
- Hai T Tran
- Department of Chemistry, University of Colorado Denver, Denver, Colorado
| | - Lauren H Anderson
- Department of Chemistry, University of Colorado Denver, Denver, Colorado
| | - Jefferson D Knight
- Department of Chemistry, University of Colorado Denver, Denver, Colorado.
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20
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Genetic dissection of neuropeptide cell biology at high and low activity in a defined sensory neuron. Proc Natl Acad Sci U S A 2018; 115:E6890-E6899. [PMID: 29959203 PMCID: PMC6055185 DOI: 10.1073/pnas.1714610115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neuropeptides are ubiquitous modulators of behavior and physiology. They are packaged in specialized secretory organelles called dense core vesicles (DCVs) that are released upon neural stimulation. Whereas local recycling of synaptic vesicles has been investigated intensively, there are few studies on recycling of DCV proteins. We set up a paradigm to study DCVs in a neuron whose activity we can control. We validate our model by confirming many previous observations on DCV cell biology. We identify a set of genes involved in recycling of DCV proteins. We also find evidence that different mechanisms of DCV priming and exocytosis may operate at high and low neural activity. Neuropeptides are ubiquitous modulators of behavior and physiology. They are packaged in specialized secretory organelles called dense core vesicles (DCVs) that are released upon neural stimulation. Unlike synaptic vesicles, which can be recycled and refilled close to release sites, DCVs must be replenished by de novo synthesis in the cell body. Here, we dissect DCV cell biology in vivo in a Caenorhabditis elegans sensory neuron whose tonic activity we can control using a natural stimulus. We express fluorescently tagged neuropeptides in the neuron and define parameters that describe their subcellular distribution. We measure these parameters at high and low neural activity in 187 mutants defective in proteins implicated in membrane traffic, neuroendocrine secretion, and neuronal or synaptic activity. Using unsupervised hierarchical clustering methods, we analyze these data and identify 62 groups of genes with similar mutant phenotypes. We explore the function of a subset of these groups. We recapitulate many previous findings, validating our paradigm. We uncover a large battery of proteins involved in recycling DCV membrane proteins, something hitherto poorly explored. We show that the unfolded protein response promotes DCV production, which may contribute to intertissue communication of stress. We also find evidence that different mechanisms of priming and exocytosis may operate at high and low neural activity. Our work provides a defined framework to study DCV biology at different neural activity levels.
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MacDougall DD, Lin Z, Chon NL, Jackman SL, Lin H, Knight JD, Anantharam A. The high-affinity calcium sensor synaptotagmin-7 serves multiple roles in regulated exocytosis. J Gen Physiol 2018; 150:783-807. [PMID: 29794152 PMCID: PMC5987875 DOI: 10.1085/jgp.201711944] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 05/07/2018] [Indexed: 12/19/2022] Open
Abstract
MacDougall et al. review the structure and function of the calcium sensor synaptotagmin-7 in exocytosis. Synaptotagmin (Syt) proteins comprise a 17-member family, many of which trigger exocytosis in response to calcium. Historically, most studies have focused on the isoform Syt-1, which serves as the primary calcium sensor in synchronous neurotransmitter release. Recently, Syt-7 has become a topic of broad interest because of its extreme calcium sensitivity and diversity of roles in a wide range of cell types. Here, we review the known and emerging roles of Syt-7 in various contexts and stress the importance of its actions. Unique functions of Syt-7 are discussed in light of recent imaging, electrophysiological, and computational studies. Particular emphasis is placed on Syt-7–dependent regulation of synaptic transmission and neuroendocrine cell secretion. Finally, based on biochemical and structural data, we propose a mechanism to link Syt-7’s role in membrane fusion with its role in subsequent fusion pore expansion via strong calcium-dependent phospholipid binding.
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Affiliation(s)
| | - Zesen Lin
- Department of Pharmacology, University of Michigan, Ann Arbor, MI
| | - Nara L Chon
- Department of Chemistry, University of Colorado, Denver, CO
| | - Skyler L Jackman
- Vollum Institute, Oregon Health & Science University, Portland, OR
| | - Hai Lin
- Department of Chemistry, University of Colorado, Denver, CO
| | | | - Arun Anantharam
- Department of Pharmacology, University of Michigan, Ann Arbor, MI
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22
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Achim K, Eling N, Vergara HM, Bertucci PY, Musser J, Vopalensky P, Brunet T, Collier P, Benes V, Marioni JC, Arendt D. Whole-Body Single-Cell Sequencing Reveals Transcriptional Domains in the Annelid Larval Body. Mol Biol Evol 2018; 35:1047-1062. [PMID: 29373712 PMCID: PMC5913682 DOI: 10.1093/molbev/msx336] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Animal bodies comprise diverse arrays of cells. To characterize cellular identities across an entire body, we have compared the transcriptomes of single cells randomly picked from dissociated whole larvae of the marine annelid Platynereis dumerilii. We identify five transcriptionally distinct groups of differentiated cells, each expressing a unique set of transcription factors and effector genes that implement cellular phenotypes. Spatial mapping of cells into a cellular expression atlas, and wholemount in situ hybridization of group-specific genes reveals spatially coherent transcriptional domains in the larval body, comprising, for example, apical sensory-neurosecretory cells versus neural/epidermal surface cells. These domains represent new, basic subdivisions of the annelid body based entirely on differential gene expression, and are composed of multiple, transcriptionally similar cell types. They do not represent clonal domains, as revealed by developmental lineage analysis. We propose that the transcriptional domains that subdivide the annelid larval body represent families of related cell types that have arisen by evolutionary diversification. Their possible evolutionary conservation makes them a promising tool for evo-devo research.
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Affiliation(s)
- Kaia Achim
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Nils Eling
- EMBL-European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, United Kingdom
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
| | | | - Paola Yanina Bertucci
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jacob Musser
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Pavel Vopalensky
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Thibaut Brunet
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Paul Collier
- Genomics Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Vladimir Benes
- Genomics Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - John C Marioni
- EMBL-European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, United Kingdom
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
| | - Detlev Arendt
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
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23
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Bendahmane M, Bohannon KP, Bradberry MM, Rao TC, Schmidtke MW, Abbineni PS, Chon NL, Tran S, Lin H, Chapman ER, Knight JD, Anantharam A. The synaptotagmin C2B domain calcium-binding loops modulate the rate of fusion pore expansion. Mol Biol Cell 2018; 29:834-845. [PMID: 29444959 PMCID: PMC5905296 DOI: 10.1091/mbc.e17-11-0623] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/22/2018] [Accepted: 02/07/2018] [Indexed: 01/19/2023] Open
Abstract
In chromaffin cells, the kinetics of fusion pore expansion vary depending on which synaptotagmin isoform (Syt-1 or Syt-7) drives release. Our recent studies have shown that fusion pores of granules harboring Syt-1 expand more rapidly than those harboring Syt-7. Here we sought to define the structural specificity of synaptotagmin action at the fusion pore by manipulating the Ca2+-binding C2B module. We generated a chimeric Syt-1 in which its C2B Ca2+-binding loops had been exchanged for those of Syt-7. Fusion pores of granules harboring a Syt-1 C2B chimera with all three Ca2+-binding loops of Syt-7 (Syt-1:7C2B123) exhibited slower rates of fusion pore expansion and neuropeptide cargo release relative to WT Syt-1. After fusion, this chimera also dispersed more slowly from fusion sites than WT protein. We speculate that the Syt-1:7 C2B123 and WT Syt-1 are likely to differ in their interactions with Ca2+ and membranes. Subsequent in vitro and in silico data demonstrated that the chimera exhibits a higher affinity for phospholipids than WT Syt-1. We conclude that the affinity of synaptotagmin for the plasma membrane, and the rate at which it releases the membrane, contribute in important ways to the rate of fusion pore expansion.
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Affiliation(s)
- Mounir Bendahmane
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109
| | - Kevin P. Bohannon
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109
| | - Mazdak M. Bradberry
- Department of Neuroscience, Howard Hughes Medical Institute. University of Wisconsin–Madison, Madison, WI 53705
| | - Tejeshwar C. Rao
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109
| | | | | | - Nara L. Chon
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217
| | - Sherleen Tran
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217
| | - Hai Lin
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217
| | - Edwin R. Chapman
- Department of Neuroscience, Howard Hughes Medical Institute. University of Wisconsin–Madison, Madison, WI 53705
| | | | - Arun Anantharam
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109
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24
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Rorsman P, Ashcroft FM. Pancreatic β-Cell Electrical Activity and Insulin Secretion: Of Mice and Men. Physiol Rev 2018; 98:117-214. [PMID: 29212789 PMCID: PMC5866358 DOI: 10.1152/physrev.00008.2017] [Citation(s) in RCA: 430] [Impact Index Per Article: 71.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/30/2017] [Accepted: 06/18/2017] [Indexed: 12/14/2022] Open
Abstract
The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity, and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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25
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Paul A, Crow M, Raudales R, He M, Gillis J, Huang ZJ. Transcriptional Architecture of Synaptic Communication Delineates GABAergic Neuron Identity. Cell 2017; 171:522-539.e20. [PMID: 28942923 DOI: 10.1016/j.cell.2017.08.032] [Citation(s) in RCA: 277] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 05/04/2017] [Accepted: 08/16/2017] [Indexed: 01/07/2023]
Abstract
Understanding the organizational logic of neural circuits requires deciphering the biological basis of neuronal diversity and identity, but there is no consensus on how neuron types should be defined. We analyzed single-cell transcriptomes of a set of anatomically and physiologically characterized cortical GABAergic neurons and conducted a computational genomic screen for transcriptional profiles that distinguish them from one another. We discovered that cardinal GABAergic neuron types are delineated by a transcriptional architecture that encodes their synaptic communication patterns. This architecture comprises 6 categories of ∼40 gene families, including cell-adhesion molecules, transmitter-modulator receptors, ion channels, signaling proteins, neuropeptides and vesicular release components, and transcription factors. Combinatorial expression of select members across families shapes a multi-layered molecular scaffold along the cell membrane that may customize synaptic connectivity patterns and input-output signaling properties. This molecular genetic framework of neuronal identity integrates cell phenotypes along multiple axes and provides a foundation for discovering and classifying neuron types.
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Affiliation(s)
- Anirban Paul
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Megan Crow
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Ricardo Raudales
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Program in Neuroscience, Stony Brook University, Stony Brook, NY 11790, USA
| | - Miao He
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Jesse Gillis
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Z Josh Huang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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26
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Jackson MB. Chemistry in a vesicle. J Gen Physiol 2017; 149:893-896. [PMID: 28899933 PMCID: PMC5694936 DOI: 10.1085/jgp.201711894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Slow fusion pore expansion could retain molecules within vesicles, enabling a chemical reaction that modifies secreted products.
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Affiliation(s)
- Meyer B Jackson
- Department of Neuroscience, University of Wisconsin, Madison, WI
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27
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van der Stijl R, Withoff S, Verbeek DS. Spinocerebellar ataxia: miRNAs expose biological pathways underlying pervasive Purkinje cell degeneration. Neurobiol Dis 2017; 108:148-158. [PMID: 28823930 DOI: 10.1016/j.nbd.2017.08.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 07/21/2017] [Accepted: 08/16/2017] [Indexed: 01/09/2023] Open
Abstract
Recent work has demonstrated the importance of miRNAs in the pathogenesis of various brain disorders including the neurodegenerative disorder spinocerebellar ataxia (SCA). This review focuses on the role of miRNAs in the shared pathogenesis of the different SCA types. We examine the novel findings of a recent cell-type-specific RNA-sequencing study in mouse brain and discuss how the identification of Purkinje-cell-enriched miRNAs highlights biological pathways that expose the mechanisms behind pervasive Purkinje cell degeneration in SCA. These key pathways are likely to contain targets for therapeutic development and represent potential candidate genes for genetically unsolved SCAs.
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Affiliation(s)
- Rogier van der Stijl
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Sebo Withoff
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Dineke S Verbeek
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands.
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28
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Kabayama H, Tokushige N, Takeuchi M, Kabayama M, Fukuda M, Mikoshiba K. Parkin promotes proteasomal degradation of synaptotagmin IV by accelerating polyubiquitination. Mol Cell Neurosci 2017; 80:89-99. [PMID: 28254618 DOI: 10.1016/j.mcn.2017.02.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/02/2017] [Accepted: 02/15/2017] [Indexed: 12/25/2022] Open
Abstract
Parkin is an E3 ubiquitin ligase whose mutations cause autosomal recessive juvenile Parkinson's disease (PD). Unlike the human phenotype, parkin knockout (KO) mice show no apparent dopamine neuron degeneration, although they demonstrate reduced expression and activity of striatal mitochondrial proteins believed to be necessary for neuronal survival. Instead, parkin-KO mice show reduced striatal evoked dopamine release, abnormal synaptic plasticity, and non-motor symptoms, all of which appear to mimic the preclinical features of Parkinson's disease. Extensive studies have screened candidate synaptic proteins responsible for reduced evoked dopamine release, and synaptotagmin XI (Syt XI), an isoform of Syt family regulating membrane trafficking, has been identified as a substrate of parkin in humans. However, its expression level is unaltered in the striatum of parkin-KO mice. Thus, the target(s) of parkin and the molecular mechanisms underlying the impaired dopamine release in parkin-KO mice remain unknown. In this study, we focused on Syt IV because of its highly homology to Syt XI, and because they share an evolutionarily conserved lack of Ca2+-binding capacity; thus, Syt IV plays an inhibitory role in Ca2+-dependent neurotransmitter release in PC12 cells and neurons in various brain regions. We found that a proteasome inhibitor increased Syt IV protein, but not Syt XI protein, in neuron-like, differentiated PC12 cells, and that parkin interacted with and polyubiquitinated Syt IV, thereby accelerating its protein turnover. Parkin overexpression selectively degraded Syt IV protein, but not Syt I protein (indispensable for Ca2+-dependent exocytosis), thus enhancing depolarization-dependent exocytosis. Furthermore, in parkin-KO mice, the level of striatal Syt IV protein was increased. Our data indicate a crucial role for parkin in the proteasomal degradation of Syt IV, and provide a potential mechanism of parkin-regulated, evoked neurotransmitter release.
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Affiliation(s)
- Hiroyuki Kabayama
- Laboratory for Developmental Neurobiology, Brain Science Institute, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Naoko Tokushige
- Laboratory for Developmental Neurobiology, Brain Science Institute, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Makoto Takeuchi
- Laboratory for Developmental Neurobiology, Brain Science Institute, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Miyuki Kabayama
- Division of Functional Morphology, Department of Basic Veterinary Medicine, School of Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonantyo, Musashino, Tokyo 180-8602, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, Brain Science Institute, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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29
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Duvoor C, Dendi VS, Marco A, Shekhawat NS, Chada A, Ravilla R, Musham CK, Mirza W, Chaudhury A. Commentary: ATP: The crucial component of secretory vesicles: Accelerated ATP/insulin exocytosis and prediabetes. Front Physiol 2017; 8:53. [PMID: 28210227 PMCID: PMC5288386 DOI: 10.3389/fphys.2017.00053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 01/19/2017] [Indexed: 02/03/2023] Open
Affiliation(s)
- Chitharanjan Duvoor
- Department of Endocrinology and Internal Medicine, University of Arkansas for Medical SciencesLittle Rock, AR, USA; GIM FoundationLittle Rock, AR, USA
| | - Vijaya S Dendi
- GIM FoundationLittle Rock, AR, USA; Department of Internal Medicine and Hospital Medicine, Christus Trinity Mother Frances HospitalTyler, TX, USA
| | - Asween Marco
- GIM FoundationLittle Rock, AR, USA; Department of Policy, University of Arkansas for Little RockLittle Rock, AR, USA
| | - Nawal S Shekhawat
- GIM FoundationLittle Rock, AR, USA; Tutwiler ClinicTutwiler, MS, USA
| | - Aditya Chada
- GIM FoundationLittle Rock, AR, USA; Department of Pulmonary and Critical Care Medicine, University of Arkansas for Medical SciencesLittle Rock, AR, USA
| | - Rahul Ravilla
- GIM FoundationLittle Rock, AR, USA; Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical SciencesLittle Rock, AR, USA
| | - Chaitanya K Musham
- GIM FoundationLittle Rock, AR, USA; St. Vincent Infirmary (Catholic Health Initiative)Little Rock, AR, USA
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30
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Pinheiro PS, Houy S, Sørensen JB. C2-domain containing calcium sensors in neuroendocrine secretion. J Neurochem 2016; 139:943-958. [DOI: 10.1111/jnc.13865] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 09/17/2016] [Accepted: 10/05/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Paulo S. Pinheiro
- Center for Neuroscience and Cell Biology; University of Coimbra; Coimbra Portugal
| | - Sébastien Houy
- Department of Neuroscience and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Jakob B. Sørensen
- Department of Neuroscience and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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31
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Siao W, Wang P, Voigt B, Hussey PJ, Baluska F. Arabidopsis SYT1 maintains stability of cortical endoplasmic reticulum networks and VAP27-1-enriched endoplasmic reticulum-plasma membrane contact sites. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:6161-6171. [PMID: 27811083 PMCID: PMC5100027 DOI: 10.1093/jxb/erw381] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Arabidopsis synaptotagmin 1 (SYT1) is localized on the endoplasmic reticulum-plasma membrane (ER-PM) contact sites in leaf and root cells. The ER-PM localization of Arabidopsis SYT1 resembles that of the extended synaptotagmins (E-SYTs) in animal cells. In mammals, E-SYTs have been shown to regulate calcium signaling, lipid transfer, and endocytosis. Arabidopsis SYT1 was reported to be essential for maintaining cell integrity and virus movement. This study provides detailed insight into the subcellular localization of SYT1 and VAP27-1, another ER-PM-tethering protein. SYT1 and VAP27-1 were shown to be localized on distinct ER-PM contact sites. The VAP27-1-enriched ER-PM contact sites (V-EPCSs) were always in contact with the SYT1-enriched ER-PM contact sites (S-EPCSs). The V-EPCSs still existed in the leaf epidermal cells of the SYT1 null mutant; however, they were less stable than those in the wild type. The polygonal networks of cortical ER disassembled and the mobility of VAP27-1 protein on the ER-PM contact sites increased in leaf cells of the SYT1 null mutant. These results suggest that SYT1 is responsible for stabilizing the ER network and V-EPCSs.
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Affiliation(s)
- Wei Siao
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany
| | - Pengwei Wang
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Boris Voigt
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany
| | - Patrick J Hussey
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Frantisek Baluska
- Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany
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32
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Identification of Synaptotagmin 10 as Effector of NPAS4-Mediated Protection from Excitotoxic Neurodegeneration. J Neurosci 2016; 36:2561-70. [PMID: 26936998 DOI: 10.1523/jneurosci.2027-15.2016] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED Neuronal degeneration represents a pathogenetic hallmark after different brain insults, such as ischemia and status epilepticus (SE). Excessive release of glutamate triggered by pathophysiologic synaptic activity has been put forward as key mechanism in this context. In response to pathophysiologic synaptic activity, multiple signaling cascades are activated that ultimately initiate expression of specific sets of genes, which may decide between neuronal survival versus death. Recently, a core set of genes ["activity-regulated inhibitor of death" (AID) genes] including the transcription factor (TF) NPAS4 (neuronal PAS domain protein 4) has been found to provide activity-induced protection against neuronal death caused by excitotoxic stimulation. However, the downstream targets of AID action mediating neuroprotection remained so far unknown. Here, we have identified synaptotagmin 10 (Syt10), a vesicular Ca(2+) sensor, as the first neuroprotective effector protein downstream of the TF NPAS4. The expression of Syt10 is strongly upregulated by pathophysiologic synaptic activity after kainic acid (KA) exposure and its absence renders mouse hippocampal neurons highly susceptible to excitotoxic insults. We found NPAS4 as critical for the increase in Syt10 levels and in turn the ability of NPAS4 to confer neuroprotection against KA-induced excitotoxicity to be severely diminished in Syt10 knock-out neurons. In summary, our results point to an important role for signaling of the NPAS4-Syt10 pathway in the neuronal response to strong synaptic activity as a consequence of excitotoxic insults. SIGNIFICANCE STATEMENT Aberrant synaptic activity is observed in many neurological disorders and has been suggested as an important factor contributing to the pathophysiology. Intriguingly, pathophysiologic activity can also trigger signaling cascades mediating potentially compensatory neuroprotection against excitotoxic insult. Here, we identify a new neuroprotective signaling cascade involving the activity-induced transcriptional regulator NPAS4 and the vesicular Ca(2+)-sensor protein synaptotagmin 10 (Syt10). Syt10 is required for NPAS4 to protect hippocampal neurons against excitotoxic cell death. NPAS4 in turn controls the activity of the Syt10 gene, which is strongly induced by pathophysiologic activity. Our results uncover an entirely unexpected, novel function of Syt10 underlying the response of neurons to pathophysiologic activity and provide new therapeutic perspectives for neurological disorders.
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33
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Cárdenas AM, Marengo FD. How the stimulus defines the dynamics of vesicle pool recruitment, fusion mode, and vesicle recycling in neuroendocrine cells. J Neurochem 2016; 137:867-79. [DOI: 10.1111/jnc.13565] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 01/05/2016] [Accepted: 01/25/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Ana María Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso; Universidad de Valparaíso; Valparaíso Chile
| | - Fernando D. Marengo
- Laboratorio de Fisiología y Biología Molecular; Instituto de Fisiología; Biología Molecular y Neurociencias (CONICET); Departamento de Fisiología y Biología Molecular y Celular; Facultad de Ciencias Exactas y Naturales; Universidad de Buenos Aires; Buenos Aires Argentina
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34
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Kekeeva T, Tanas A, Kanygina A, Alexeev D, Shikeeva A, Zavalishina L, Andreeva Y, Frank GA, Zaletaev D. Novel fusion transcripts in bladder cancer identified by RNA-seq. Cancer Lett 2016; 374:224-8. [PMID: 26898937 DOI: 10.1016/j.canlet.2016.02.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/29/2016] [Accepted: 02/05/2016] [Indexed: 10/25/2022]
Abstract
Urothelial carcinoma (UC) is the most common type of bladder cancer and is the second most frequently diagnosed genitourinary tumor. The identification of fusion genes in bladder cancer might provide new perspectives for its classification and significance. In this study, we present a thorough search on three UC samples for novel fusion transcripts in bladder cancer using high-throughput RNA sequencing. We used stringent requirements for 819 fusion candidates and nominated 10 candidate fusion transcripts. Among them four novel fusion genes SEPT9/CYHR, IGF1R/TTC23, SYT8/TNNI2 and CASZ1/DFFA were validated and characterized in 48 formalin-fixed paraffin-embedded (FFPE) specimens of bladder cancer. Chromosomal rearrangements of regions 17q25, 15q26.3 and 1p36.22 resulting in the fusion transcripts SEPT9/CYHR, IGF1R/TTC23 and CASZ1/DFFA, appeared to be rare or unique events because they were not detected in the 48 UC samples. In contrast, the SYT8/TNNI2 fusion transcript resulting from transcription-induced chimerism by read-through mechanisms was a rather common and tumor-specific event occurring in 37.5% (18/48) of the UC specimens. Further investigation of functional and clinical relevance of novel fusion genes remains to be elucidated to reveal their role in bladder carcinogenesis.
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Affiliation(s)
- T Kekeeva
- Laboratory of Epigenetics, Research Centre for Medical Genetics, Moskvorechie st., 1, Moscow, 115478, Russian Federation; Pathology Department, Russian Medical Academy of Postgraduate Education, Polikarpov st., 12, Moscow, 125284, Russian Federation.
| | - A Tanas
- Laboratory of Epigenetics, Research Centre for Medical Genetics, Moskvorechie st., 1, Moscow, 115478, Russian Federation
| | - A Kanygina
- Department of Molecular Biophysics, Moscow Institute of Physics and Technology, Institutskii Per. 9, Moscow Region, Dolgoprudny, 141700, Russian Federation
| | - D Alexeev
- Medical and Rehabilitation Center of Ministry of Healthcare of Russian Federation, Ivankovskoye, 3, Moscow, 125367, Russian Federation; Department of Molecular Biophysics, Moscow Institute of Physics and Technology, Institutskii Per. 9, Moscow Region, Dolgoprudny, 141700, Russian Federation
| | - A Shikeeva
- Laboratory of Epigenetics, Research Centre for Medical Genetics, Moskvorechie st., 1, Moscow, 115478, Russian Federation; Pathology Department, Russian Medical Academy of Postgraduate Education, Polikarpov st., 12, Moscow, 125284, Russian Federation
| | - L Zavalishina
- Pathology Department, Russian Medical Academy of Postgraduate Education, Polikarpov st., 12, Moscow, 125284, Russian Federation
| | - Y Andreeva
- Pathology Department, Russian Medical Academy of Postgraduate Education, Polikarpov st., 12, Moscow, 125284, Russian Federation
| | - G A Frank
- Pathology Department, Russian Medical Academy of Postgraduate Education, Polikarpov st., 12, Moscow, 125284, Russian Federation
| | - D Zaletaev
- Laboratory of Epigenetics, Research Centre for Medical Genetics, Moskvorechie st., 1, Moscow, 115478, Russian Federation; Laboratory of Human Molecular Genetics, I. M. Sechenov First Moscow State Medical University, Trubetskaya Str., 8, Moscow 119991, Russian Federation
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35
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Hopping Pits Catch Fusing Granules. Dev Cell 2016; 35:10-1. [PMID: 26460943 DOI: 10.1016/j.devcel.2015.09.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In excitable cells, regulated exocytosis is coupled to endocytic membrane retrieval. Yuan et al. (2015) in this issue of Developmental Cell report a possible mechanism for such exo-endocytic coupling that is based on stimulation-induced hopping of clathrin-containing endocytic structures to nascent sites of insulin granule fusion.
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Sex-specific regulation of follicle-stimulating hormone secretion by synaptotagmin 9. Nat Commun 2015; 6:8645. [PMID: 26482442 PMCID: PMC4620939 DOI: 10.1038/ncomms9645] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 09/11/2015] [Indexed: 12/24/2022] Open
Abstract
The anterior pituitary releases six different hormones that control virtually all aspects of vertebrate physiology, yet the molecular mechanisms underlying their Ca(2+)-triggered release remain unknown. A subset of the synaptotagmin (syt) family of proteins serve as Ca(2+) sensors for exocytosis in neurons and neuroendocrine cells, and are thus likely to regulate pituitary hormone secretion. Here we show that numerous syt isoforms are highly expressed in the pituitary gland in a lobe, and sex-specific manner. We further investigated a Ca(2+)-activated isoform, syt-9, and found that it is expressed in a subpopulation of anterior pituitary cells, the gonadotropes. Follicle-stimulating hormone (FSH) and syt-9 are highly co-localized in female, but not male, mice. Loss of syt-9 results in diminished basal and stimulated FSH secretion only in females, resulting in alterations in the oestrus cycle. This work uncovers a new function for syt-9 and reveals a novel sex difference in reproductive hormone secretion.
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37
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Levy A, Zheng JY, Lazarowitz SG. Synaptotagmin SYTA forms ER-plasma membrane junctions that are recruited to plasmodesmata for plant virus movement. Curr Biol 2015; 25:2018-25. [PMID: 26166780 DOI: 10.1016/j.cub.2015.06.015] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 05/28/2015] [Accepted: 06/05/2015] [Indexed: 11/20/2022]
Abstract
Metazoan synaptotagmins are Ca(2+) sensors that regulate exocytosis and endocytosis in various cell types, notably in nerve and neuroendocrine cells [1, 2]. Recently, the structurally related extended synaptotagmins were shown to tether the cortical ER to the plasma membrane in human and yeast cells to maintain ER morphology and stabilize ER-plasma membrane (ER-PM) contact sites for intracellular lipid and Ca(2+) signaling [3, 4]. The Arabidopsis synaptotagmin SYTA regulates endocytosis and the ability of plant virus movement proteins (MPs) to alter plasmodesmata to promote virus cell-to-cell transport [5, 6]. Yet how MPs modify plasmodesmata, the cellular functions of SYTA and how these aid MP activity, and the proteins essential to form plant cell ER-PM contact sites remain unknown. We addressed these questions using an Arabidopsis SYTA knockdown line syta-1 and a Tobamovirus movement protein MP(TVCV) [5, 7]. We report here that SYTA localized to ER-PM contact sites. These sites were depleted and the ER network collapsed in syta-1, and both reformed upon rescue with SYTA. MP(TVCV) accumulation in plasmodesmata, but not secretory trafficking, was also inhibited in syta-1. During infection, MP(TVCV) recruited SYTA to plasmodesmata, and SYTA and the cortical ER were subsequently remodeled to form viral replication sites adjacent to plasmodesmata in which MP(TVCV) and SYTA directly interacted caged within ER membrane. SYTA also accumulated in plasmodesmata active in MP(TVCV) transport. Our findings show that SYTA is essential to form ER-PM contact sites and suggest that MPs interact with SYTA to recruit these sites to alter plasmodesmata for virus cell-to-cell movement.
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Affiliation(s)
- Amit Levy
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Judy Y Zheng
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Sondra G Lazarowitz
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA.
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Hui ST, Parks BW, Org E, Norheim F, Che N, Pan C, Castellani LW, Charugundla S, Dirks DL, Psychogios N, Neuhaus I, Gerszten RE, Kirchgessner T, Gargalovic PS, Lusis AJ. The genetic architecture of NAFLD among inbred strains of mice. eLife 2015; 4:e05607. [PMID: 26067236 PMCID: PMC4493743 DOI: 10.7554/elife.05607] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 06/11/2015] [Indexed: 02/06/2023] Open
Abstract
To identify genetic and environmental factors contributing to the pathogenesis of non-alcoholic fatty liver disease, we examined liver steatosis and related clinical and molecular traits in more than 100 unique inbred mouse strains, which were fed a diet rich in fat and carbohydrates. A >30-fold variation in hepatic TG accumulation was observed among the strains. Genome-wide association studies revealed three loci associated with hepatic TG accumulation. Utilizing transcriptomic data from the liver and adipose tissue, we identified several high-confidence candidate genes for hepatic steatosis, including Gde1, a glycerophosphodiester phosphodiesterase not previously implicated in triglyceride metabolism. We confirmed the role of Gde1 by in vivo hepatic over-expression and shRNA knockdown studies. We hypothesize that Gde1 expression increases TG production by contributing to the production of glycerol-3-phosphate. Our multi-level data, including transcript levels, metabolite levels, and gut microbiota composition, provide a framework for understanding genetic and environmental interactions underlying hepatic steatosis.
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Affiliation(s)
- Simon T Hui
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Brian W Parks
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Elin Org
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Frode Norheim
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Nam Che
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Calvin Pan
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Lawrence W Castellani
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Sarada Charugundla
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Darwin L Dirks
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Nikolaos Psychogios
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Isaac Neuhaus
- Department of Computational Genomics, Bristol-Myers Squibb, Princeton, United States
| | - Robert E Gerszten
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Todd Kirchgessner
- Department of Cardiovascular Drug Discovery, Bristol-Myers Squibb, Princeton, United States
| | - Peter S Gargalovic
- Department of Computational Genomics, Bristol-Myers Squibb, Princeton, United States
| | - Aldons J Lusis
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
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The synaptotagmin juxtamembrane domain is involved in neuroexocytosis. FEBS Open Bio 2015; 5:388-96. [PMID: 25973365 PMCID: PMC4427626 DOI: 10.1016/j.fob.2015.04.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 04/21/2015] [Accepted: 04/23/2015] [Indexed: 12/21/2022] Open
Abstract
The highly cationic juxtamembrane segment of synaptotagmin juxtamembrane domain was synthesized. This peptide inhibits neurotransmitter release at the neuromuscular junction of mice and Drosophila. This peptide localizes mainly on the presynaptic membrane. The synaptotagmin juxtamembrane peptide binds monophosphoinositides in a Ca2+-independent manner. The juxtamembrane segment of synaptotagmin may contribute to the formation of the hemifusion intermediate.
Synaptotagmin is a synaptic vesicle membrane protein which changes conformation upon Ca2+ binding and triggers the fast neuroexocytosis that takes place at synapses. We have synthesized a series of peptides corresponding to the sequence of the cytosolic juxtamembrane domain of synaptotagmin, which is highly conserved among different isoforms and animal species, with or without either a hexyl hydrophobic chain or the hexyl group plus a fluorescein moiety. We show that these peptides inhibit neurotransmitter release, that they localize on the presynaptic membrane of the motor axon terminal at the neuromuscular junction and that they bind monophosphoinositides in a Ca2+-independent manner. Based on these findings, we propose that the juxtamembrane cytosolic domain of synaptotagmin binds the cytosolic layer of the presynaptic membrane at rest. This binding brings synaptic vesicles and plasma membrane in a very close apposition, favouring the formation of hemifusion intermediates that enable rapid vesicle fusion.
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Key Words
- Anionic phospholipids
- JMS, juxtamembrane segment
- Juxtamembrane domain
- NMJ, neuromuscular junction
- Neuroexocytosis
- Neuromuscular junction
- PM, presynaptic membrane
- SV, synaptic vesicles
- Synaptotagmin
- Syt, synaptotagmin
- TM, transmembrane
- h-FJMS, hexyl fluorescent juxtamembrane segment
- h-JMS, hexyl juxtamembrane segment
- h-sJMS, hexyl scrambled juxtamembrane segment
- α-BTX, alpha-bungarotoxin
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Tremblay MG, Herdman C, Guillou F, Mishra PK, Baril J, Bellenfant S, Moss T. Extended Synaptotagmin Interaction with the Fibroblast Growth Factor Receptor Depends on Receptor Conformation, Not Catalytic Activity. J Biol Chem 2015; 290:16142-56. [PMID: 25922075 DOI: 10.1074/jbc.m115.656918] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Indexed: 11/06/2022] Open
Abstract
We previously demonstrated that ESyt2 interacts specifically with the activated FGF receptor and is required for a rapid phase of receptor internalization and for functional signaling via the ERK pathway in early Xenopus embryos. ESyt2 is one of the three-member family of Extended Synaptotagmins that were recently shown to be implicated in the formation of endoplasmic reticulum (ER)-plasma membrane (PM) junctions and in the Ca(2+) dependent regulation of these junctions. Here we show that ESyt2 is directed to the ER by its putative transmembrane domain, that the ESyts hetero- and homodimerize, and that ESyt2 homodimerization in vivo requires a TM adjacent sequence but not the SMP domain. ESyt2 and ESyt3, but not ESyt1, selectively interact in vivo with activated FGFR1. In the case of ESyt2, this interaction requires a short TM adjacent sequence and is independent of receptor autophosphorylation, but dependent on receptor conformation. The data show that ESyt2 recognizes a site in the upper kinase lobe of FGFR1 that is revealed by displacement of the kinase domain activation loop during receptor activation.
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Affiliation(s)
- Michel G Tremblay
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Chelsea Herdman
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - François Guillou
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Prakash K Mishra
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Joëlle Baril
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Sabrina Bellenfant
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
| | - Tom Moss
- From the Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Québec University Hospital Research Centre, and Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Edifice St Patrick, 9 rue McMahon, Québec, Québec G1R 3S3, Canada
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McAdams RM, McPherson RJ, Beyer RP, Bammler TK, Farin FM, Juul SE. Dose-dependent effects of morphine exposure on mRNA and microRNA (miR) expression in hippocampus of stressed neonatal mice. PLoS One 2015; 10:e0123047. [PMID: 25844808 PMCID: PMC4386824 DOI: 10.1371/journal.pone.0123047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 02/18/2015] [Indexed: 12/02/2022] Open
Abstract
Morphine is used to sedate critically ill infants to treat painful or stressful conditions associated with intensive care. Whether neonatal morphine exposure affects microRNA (miR) expression and thereby alters mRNA regulation is unknown. We tested the hypothesis that repeated morphine treatment in stress-exposed neonatal mice alters hippocampal mRNA and miR expression. C57BL/6 male mice were treated from postnatal day (P) 5 to P9 with morphine sulfate at 2 or 5 mg/kg ip twice daily and then exposed to stress consisting of hypoxia (100% N2 1 min and 100% O2 5 min) followed by 2h maternal separation. Control mice were untreated and dam-reared. mRNA and miR expression profiling was performed on hippocampal tissues at P9. Overall, 2 and 5 mg/kg morphine treatment altered expression of a total of 150 transcripts (>1.5 fold change, P<0.05) from which 100 unique mRNAs were recognized (21 genes were up- and 79 genes were down-regulated), and 5 mg/kg morphine affected 63 mRNAs exclusively. The most upregulated mRNAs were fidgetin, arginine vasopressin, and resistin-like alpha, and the most down-regulated were defensin beta 11, aquaporin 1, calmodulin-like 4, chloride intracellular channel 6, and claudin 2. Gene Set Enrichment Analysis revealed that morphine treatment affected pathways related to cell cycle, membrane function, signaling, metabolism, cell death, transcriptional regulation, and immune response. Morphine decreased expression of miR-204-5p, miR-455-3p, miR-448-5p, and miR-574-3p. Nine morphine-responsive mRNAs that are involved in neurodevelopment, neurotransmission, and inflammation are predicted targets of the aforementioned differentially expressed miRs. These data establish that morphine produces dose-dependent changes in both hippocampal mRNA and miR expression in stressed neonatal mice. If permanent, morphine–mediated neuroepigenetic effects may affect long-term hippocampal function, and this provides a mechanism for the neonatal morphine-related impairment of adult learning.
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Affiliation(s)
- Ryan M. McAdams
- Department of Pediatrics, Division of Neonatology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| | - Ronald J. McPherson
- Department of Pediatrics, Division of Neonatology, University of Washington, Seattle, Washington, United States of America
| | - Richard P. Beyer
- Dept of Environmental & Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America
| | - Theo K. Bammler
- Dept of Environmental & Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America
| | - Frederico M. Farin
- Dept of Environmental & Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America
| | - Sandra E. Juul
- Department of Pediatrics, Division of Neonatology, University of Washington, Seattle, Washington, United States of America
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42
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Cioli C, Abdi H, Beaton D, Burnod Y, Mesmoudi S. Differences in human cortical gene expression match the temporal properties of large-scale functional networks. PLoS One 2014; 9:e115913. [PMID: 25546015 PMCID: PMC4278769 DOI: 10.1371/journal.pone.0115913] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 11/28/2014] [Indexed: 12/12/2022] Open
Abstract
We explore the relationships between the cortex functional organization and genetic expression (as provided by the Allen Human Brain Atlas). Previous work suggests that functional cortical networks (resting state and task based) are organized as two large networks (differentiated by their preferred information processing mode) shaped like two rings. The first ring–Visual-Sensorimotor-Auditory (VSA)–comprises visual, auditory, somatosensory, and motor cortices that process real time world interactions. The second ring–Parieto-Temporo-Frontal (PTF)–comprises parietal, temporal, and frontal regions with networks dedicated to cognitive functions, emotions, biological needs, and internally driven rhythms. We found–with correspondence analysis–that the patterns of expression of the 938 genes most differentially expressed across the cortex organized the cortex into two sets of regions that match the two rings. We confirmed this result using discriminant correspondence analysis by showing that the genetic profiles of cortical regions can reliably predict to what ring these regions belong. We found that several of the proteins–coded by genes that most differentiate the rings–were involved in neuronal information processing such as ionic channels and neurotransmitter release. The systematic study of families of genes revealed specific proteins within families preferentially expressed in each ring. The results showed strong congruence between the preferential expression of subsets of genes, temporal properties of the proteins they code, and the preferred processing modes of the rings. Ionic channels and release-related proteins more expressed in the VSA ring favor temporal precision of fast evoked neural transmission (Sodium channels SCNA1, SCNB1 potassium channel KCNA1, calcium channel CACNA2D2, Synaptotagmin SYT2, Complexin CPLX1, Synaptobrevin VAMP1). Conversely, genes expressed in the PTF ring favor slower, sustained, or rhythmic activation (Sodium channels SCNA3, SCNB3, SCN9A potassium channels KCNF1, KCNG1) and facilitate spontaneous transmitter release (calcium channel CACNA1H, Synaptotagmins SYT5, Complexin CPLX3, and synaptobrevin VAMP2).
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Affiliation(s)
- Claudia Cioli
- Laboratoire d’Imagerie Biomédicale. UMR 7371/UMR S 1146, Sorbonne Universités, UPMC Université Paris 06, Paris, France
- ISC-PIF (Institut des Systèmes Complexes de Paris-Île-de-France), Paris, France
- * E-mail:
| | - Hervé Abdi
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, United States of America
| | - Derek Beaton
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, United States of America
| | - Yves Burnod
- Laboratoire d’Imagerie Biomédicale. UMR 7371/UMR S 1146, Sorbonne Universités, UPMC Université Paris 06, Paris, France
- ISC-PIF (Institut des Systèmes Complexes de Paris-Île-de-France), Paris, France
| | - Salma Mesmoudi
- ISC-PIF (Institut des Systèmes Complexes de Paris-Île-de-France), Paris, France
- Sorbonne Universités, Paris-1 Université, Equipement d’Excellence MATRICE, Paris, France
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43
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Neuland K, Sharma N, Frick M. Synaptotagmin-7 links fusion-activated Ca²⁺ entry and fusion pore dilation. J Cell Sci 2014; 127:5218-27. [PMID: 25344253 PMCID: PMC4265738 DOI: 10.1242/jcs.153742] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Ca(2+)-dependent regulation of fusion pore dilation and closure is a key mechanism determining the output of cellular secretion. We have recently described 'fusion-activated' Ca(2+) entry (FACE) following exocytosis of lamellar bodies in alveolar type II cells. FACE regulates fusion pore expansion and facilitates secretion. However, the mechanisms linking this locally restricted Ca(2+) signal and fusion pore expansion were still elusive. Here, we demonstrate that synaptotagmin-7 (Syt7) is expressed on lamellar bodies and links FACE and fusion pore dilation. We directly assessed dynamic changes in fusion pore diameters by analysing diffusion of fluorophores across fusion pores. Expressing wild-type Syt7 or a mutant Syt7 with impaired Ca(2+)-binding to the C2 domains revealed that binding of Ca(2+) to the C2A domain facilitates FACE-induced pore dilation, probably by inhibiting translocation of complexin-2 to fused vesicles. However, the C2A domain hampered Ca(2+)-dependent exocytosis of lamellar bodies. These findings support the hypothesis that Syt7 modulates fusion pore expansion in large secretory organelles and extend our picture that lamellar bodies contain the necessary molecular inventory to facilitate secretion during the exocytic post-fusion phase. Moreover, regulating Syt7 levels on lamellar bodies appears to be essential in order that exocytosis is not impeded during the pre-fusion phase.
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Affiliation(s)
- Kathrin Neuland
- Institute of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Neeti Sharma
- Institute of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
| | - Manfred Frick
- Institute of General Physiology, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm, Germany
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Luan X, Luo L, Cao Z, Li R, Liu D, Gao M, Liu M, Wang L. Molecular cloning and expression analysis of the synaptotagmin-1 gene in the hypothalamus and pituitary of Huoyan goose during different stages of the egg-laying cycle. Reprod Biol Endocrinol 2014; 12:83. [PMID: 25146222 PMCID: PMC4147189 DOI: 10.1186/1477-7827-12-83] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 08/16/2014] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Synaptotagmin-1 (Syt1) is an abundant, evolutionarily conserved integral membrane protein that plays essential roles in neurotransmitter release and hormone secretion. Neurotransmitters secreted by hypothalamic neurons can alter GnRH (gonadotropin-releasing hormones) neuronal activity by binding to and activating specific membrane receptors in pituitary cells and, in turn, control the release of gonadotropin hormones from the pituitary gland. To reveal the influence of Syt1 on the process of goose egg-laying, we cloned and characterized the cDNA of goose Syt1 originating from hypothalamus and pituitary tissues of Huoyan goose and investigated the mRNA expression profiles during different stages of the egg-laying cycle. METHODS Hypothalamus and pituitary tissues were obtained from 36 Huoyan geese in the pre-laying period, early laying period, peak-laying period, and ceased period. The cDNA sequences of goose Syt1 were cloned and characterized from Huoyan goose tissues using 5'-RACE and 3'-RACE methods. Multiple alignments and phylogenetic analyses of the deduced Syt1 amino acid sequence were conducted using bioinformatics tools. The expression profiles of the Syt1 mRNA in the hypothalamus and pituitary during pre-laying, early laying, peak-laying and ceased period were examined using real-time PCR (qRT-PCR). RESULTS The cDNA of Syt1 consisted of a 274 bp 5' UTR, a 1266 bp open reading frame (ORF) encoding 421 amino acids, and a 519 bp 3' UTR. The deduced amino acid sequence of goose Syt1 is highly conserved with the sequence from other species, especially with birds (more than 98%), and contains two protein kinase C2 conserved regions (C2 domain) from amino acids residue 157 to 259 and 288 to 402. The results of qRT-PCR demonstrated that the expression of Syt1 mRNA increased from the pre-laying period to the peak-laying period, reached its peak in the peak-laying period, and then decreased in the ceased period. CONCLUSIONS To the best of our knowledge, this study is the first to obtain full-length cDNA sequences of the goose Syt1 gene, and the results of Syt1 mRNA expression profiling in the hypothalamus and pituitary tissues suggested that Syt1 may play an important role in regulating the secretion of hormones relevant to the reproduction and egg-laying of female geese.
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Affiliation(s)
- Xinhong Luan
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866 China
| | - Lina Luo
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866 China
| | - Zhongzan Cao
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866 China
| | - Rongrong Li
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866 China
| | - Dawei Liu
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866 China
| | - Ming Gao
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866 China
| | - Mei Liu
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, 110866 China
| | - Laiyou Wang
- Liaoning Province Livestock and Poultry Genetic Resources Conservation and Utilization Center, Liaoyang, 111000 China
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Rao TC, Passmore DR, Peleman AR, Das M, Chapman ER, Anantharam A. Distinct fusion properties of synaptotagmin-1 and synaptotagmin-7 bearing dense core granules. Mol Biol Cell 2014; 25:2416-27. [PMID: 24943843 PMCID: PMC4142614 DOI: 10.1091/mbc.e14-02-0702] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Adrenal chromaffin cells express two synaptotagmin isoforms, Syt-1 and Syt-7. Isoforms are usually sorted to separate secretory granules, are differentially activated by depolarizing stimuli, and favor discrete modes of exocytosis. It is proposed that stimulus/Ca+-dependent secretion in the chromaffin cell relies on selective Syt isoform activation. Adrenal chromaffin cells release hormones and neuropeptides that are essential for physiological homeostasis. During this process, secretory granules fuse with the plasma membrane and deliver their cargo to the extracellular space. It was once believed that fusion was the final regulated step in exocytosis, resulting in uniform and total release of granule cargo. Recent evidence argues for nonuniform outcomes after fusion, in which cargo is released with variable kinetics and selectivity. The goal of this study was to identify factors that contribute to the different outcomes, with a focus on the Ca2+-sensing synaptotagmin (Syt) proteins. Two Syt isoforms are expressed in chromaffin cells: Syt-1 and Syt-7. We find that overexpressed and endogenous Syt isoforms are usually sorted to separate secretory granules and are differentially activated by depolarizing stimuli. In addition, overexpressed Syt-1 and Syt-7 impose distinct effects on fusion pore expansion and granule cargo release. Syt-7 pores usually fail to expand (or reseal), slowing the dispersal of lumenal cargo proteins and granule membrane proteins. On the other hand, Syt-1 diffuses from fusion sites and promotes the release of lumenal cargo proteins. These findings suggest one way in which chromaffin cells may regulate cargo release is via differential activation of synaptotagmin isoforms.
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Affiliation(s)
- Tejeshwar C Rao
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Daniel R Passmore
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Andrew R Peleman
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Madhurima Das
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
| | - Edwin R Chapman
- Howard Hughes Medical Institute, Department of Neuroscience, University of Wisconsin, Madison, WI 53705
| | - Arun Anantharam
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202
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Messenger SW, Falkowski MA, Groblewski GE. Ca²⁺-regulated secretory granule exocytosis in pancreatic and parotid acinar cells. Cell Calcium 2014; 55:369-75. [PMID: 24742357 DOI: 10.1016/j.ceca.2014.03.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/04/2014] [Accepted: 03/09/2014] [Indexed: 01/09/2023]
Abstract
Protein secretion from acinar cells of the pancreas and parotid glands is controlled by G-protein coupled receptor activation and generation of the cellular messengers Ca(2+), diacylglycerol and cAMP. Secretory granule (SG) exocytosis shares some common characteristics with nerve, neuroendocrine and endocrine cells which are regulated mainly by elevated cell Ca(2+). However, in addition to diverse signaling pathways, acinar cells have large ∼1 μm diameter SGs (∼30 fold larger diameter than synaptic vesicles), respond to stimulation at slower rates (seconds versus milliseconds), demonstrate significant constitutive secretion, and in isolated acini, undergo sequential compound SG-SG exocytosis at the apical membrane. Exocytosis proceeds as an initial rapid phase that peaks and declines over 3 min followed by a prolonged phase that decays to near basal levels over 20-30 min. Studies indicate the early phase is triggered by Ca(2+) and involves the SG proteins VAMP2 (vesicle associated membrane protein2), Ca(2+)-sensing protein synatotagmin 1 (syt1) and the accessory protein complexin 2. The molecular details for regulation of VAMP8-mediated SG exocytosis and the prolonged phase of secretion are still emerging. Here we review the known regulatory molecules that impact the sequential exocytic process of SG tethering, docking, priming and fusion in acinar cells.
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Affiliation(s)
- Scott W Messenger
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States
| | - Michelle A Falkowski
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States
| | - Guy E Groblewski
- Department of Nutritional Sciences, Graduate Program in Biochemical and Molecular Nutrition, University of Wisconsin, Madison, WI 53706, United States.
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Uchiyama A, Shimada-Beltran H, Levy A, Zheng JY, Javia PA, Lazarowitz SG. The Arabidopsis synaptotagmin SYTA regulates the cell-to-cell movement of diverse plant viruses. FRONTIERS IN PLANT SCIENCE 2014; 5:584. [PMID: 25414709 PMCID: PMC4222171 DOI: 10.3389/fpls.2014.00584] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 10/09/2014] [Indexed: 05/20/2023]
Abstract
Synaptotagmins are a large gene family in animals that have been extensively characterized due to their role as calcium sensors to regulate synaptic vesicle exocytosis and endocytosis in neurons, and dense core vesicle exocytosis for hormone secretion from neuroendocrine cells. Thought to be exclusive to animals, synaptotagmins have recently been characterized in Arabidopsis thaliana, in which they comprise a five gene family. Using infectivity and leaf-based functional assays, we have shown that Arabidopsis SYTA regulates endocytosis and marks an endosomal vesicle recycling pathway to regulate movement protein-mediated trafficking of the Begomovirus Cabbage leaf curl virus (CaLCuV) and the Tobamovirus Tobacco mosaic virus (TMV) through plasmodesmata (Lewis and Lazarowitz, 2010). To determine whether SYTA has a central role in regulating the cell-to-cell trafficking of a wider range of diverse plant viruses, we extended our studies here to examine the role of SYTA in the cell-to-cell movement of additional plant viruses that employ different modes of movement, namely the Potyvirus Turnip mosaic virus (TuMV), the Caulimovirus Cauliflower mosaic virus (CaMV) and the Tobamovirus Turnip vein clearing virus (TVCV), which in contrast to TMV does efficiently infect Arabidopsis. We found that both TuMV and TVCV systemic infection, and the cell-to-cell trafficking of the their movement proteins, were delayed in the Arabidopsis Col-0 syta-1 knockdown mutant. In contrast, CaMV systemic infection was not inhibited in syta-1. Our studies show that SYTA is a key regulator of plant virus intercellular movement, being necessary for the ability of diverse cell-to-cell movement proteins encoded by Begomoviruses (CaLCuV MP), Tobamoviruses (TVCV and TMV 30K protein) and Potyviruses (TuMV P3N-PIPO) to alter PD and thereby mediate virus cell-to-cell spread.
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Affiliation(s)
| | | | | | | | | | - Sondra G. Lazarowitz
- *Correspondence: Sondra G. Lazarowitz, Department of Plant Pathology and Plant-Microbe Biology, Cornell University, 334 Plant Science Bldg., Ithaca, NY 14853, USA e-mail:
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48
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Vazquez-Martinez R, Gasman S. The regulated secretory pathway in neuroendocrine cells. Front Endocrinol (Lausanne) 2014; 5:48. [PMID: 24782828 PMCID: PMC3986512 DOI: 10.3389/fendo.2014.00048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 03/24/2014] [Indexed: 12/25/2022] Open
Affiliation(s)
- Rafael Vazquez-Martinez
- Department of Cell Biology, Physiology and Immunology, Instituto Maimónides de Investigaciones Biomédicas de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Córdoba, Spain
- *Correspondence: ;
| | - Stéphane Gasman
- Centre National de la Recherche Scientifique (CNRS UPR 3212), Institut des Neurosciences Cellulaires et Intégratives (INCI), Université de Strasbourg, Strasbourg, France
- *Correspondence: ;
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