1
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Guang X, Lan T, Wan QH, Huang Y, Li H, Zhang M, Li R, Zhang Z, Lei Y, Zhang L, Zhang H, Li D, Li X, Li H, Xu Y, Qiao M, Wu D, Tang K, Zhao P, Lin JQ, Kumar Sahu S, Liang Q, Jiang W, Zhang D, Xu X, Liu X, Lisby M, Yang H, Kristiansen K, Liu H, Fang SG. Chromosome-scale genomes provide new insights into subspecies divergence and evolutionary characteristics of the giant panda. Sci Bull (Beijing) 2021; 66:2002-2013. [PMID: 36654170 DOI: 10.1016/j.scib.2021.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 09/27/2020] [Accepted: 12/25/2020] [Indexed: 02/03/2023]
Abstract
Extant giant pandas are divided into Sichuan and Qinling subspecies. The giant panda has many species-specific characteristics, including comparatively small organs for body size, small genitalia of male individuals, and low reproduction. Here, we report the most contiguous, high-quality chromosome-level genomes of two extant giant panda subspecies to date, with the first genome assembly of the Qinling subspecies. Compared with the previously assembled giant panda genomes based on short reads, our two assembled genomes increased contiguity over 200-fold at the contig level. Additional sequencing of 25 individuals dated the divergence of the Sichuan and Qinling subspecies into two distinct clusters from 10,000 to 12,000 years ago. Comparative genomic analyses identified the loss of regulatory elements in the dachshund family transcription factor 2 (DACH2) gene and specific changes in the synaptotagmin 6 (SYT6) gene, which may be responsible for the reduced fertility of the giant panda. Positive selection analysis between the two subspecies indicated that the reproduction-associated IQ motif containing D (IQCD) gene may at least partly explain the different reproduction rates of the two subspecies. Furthermore, several genes in the Hippo pathway exhibited signs of rapid evolution with giant panda-specific variants and divergent regulatory elements, which may contribute to the reduced inner organ sizes of the giant panda.
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Affiliation(s)
- Xuanmin Guang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, China; State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China
| | - Tianming Lan
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China; Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Qiu-Hong Wan
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yan Huang
- Key Laboratory of State Forestry and Grassland Administration (State Park Administration) on Conservation Biology of Rare Animals in the Giant Panda National Park, China Conservation and Research Center for the Giant Panda, Dujiangyan 611830, China
| | - Hong Li
- Novogene Bioinformatics Institute, Beijing 100083, China
| | - Mingchun Zhang
- Key Laboratory of State Forestry and Grassland Administration (State Park Administration) on Conservation Biology of Rare Animals in the Giant Panda National Park, China Conservation and Research Center for the Giant Panda, Dujiangyan 611830, China
| | - Rengui Li
- Key Laboratory of State Forestry and Grassland Administration (State Park Administration) on Conservation Biology of Rare Animals in the Giant Panda National Park, China Conservation and Research Center for the Giant Panda, Dujiangyan 611830, China
| | - Zhizhong Zhang
- Key Laboratory of State Forestry and Grassland Administration (State Park Administration) on Conservation Biology of Rare Animals in the Giant Panda National Park, China Conservation and Research Center for the Giant Panda, Dujiangyan 611830, China
| | - Yinghu Lei
- Qinling Research Center of Giant Panda Breeding, Shaanxi Academy of Forestry, Xi'an 710082, China
| | - Ling Zhang
- China Wildlife Conservation Association, Beijing 100714, China
| | - Heming Zhang
- Key Laboratory of State Forestry and Grassland Administration (State Park Administration) on Conservation Biology of Rare Animals in the Giant Panda National Park, China Conservation and Research Center for the Giant Panda, Dujiangyan 611830, China
| | - Desheng Li
- Key Laboratory of State Forestry and Grassland Administration (State Park Administration) on Conservation Biology of Rare Animals in the Giant Panda National Park, China Conservation and Research Center for the Giant Panda, Dujiangyan 611830, China
| | - Xiaoping Li
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China; Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Haimeng Li
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China
| | - Yan Xu
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China
| | - Maiju Qiao
- Key Laboratory of State Forestry and Grassland Administration (State Park Administration) on Conservation Biology of Rare Animals in the Giant Panda National Park, China Conservation and Research Center for the Giant Panda, Dujiangyan 611830, China
| | - Daifu Wu
- Key Laboratory of State Forestry and Grassland Administration (State Park Administration) on Conservation Biology of Rare Animals in the Giant Panda National Park, China Conservation and Research Center for the Giant Panda, Dujiangyan 611830, China
| | - Keyi Tang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Pengpeng Zhao
- Qinling Research Center of Giant Panda Breeding, Shaanxi Academy of Forestry, Xi'an 710082, China
| | - Jian-Qing Lin
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Sunil Kumar Sahu
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China
| | - Qiqi Liang
- Novogene Bioinformatics Institute, Beijing 100083, China
| | - Wenkai Jiang
- Novogene Bioinformatics Institute, Beijing 100083, China
| | - Danhui Zhang
- Qinling Research Center of Giant Panda Breeding, Shaanxi Academy of Forestry, Xi'an 710082, China
| | - Xun Xu
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China; Guangdong Provincial Key Laboratory of Genome Read and Write, BGI-Shenzhen, Shenzhen 518120, China
| | - Xin Liu
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China
| | - Michael Lisby
- Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Huanming Yang
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China; Guangdong Provincial Academician Workstation of BGI Synthetic Genomics, BGI-Shenzhen, Shenzhen 518120, China
| | - Karsten Kristiansen
- Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark; Qingdao-Europe Advanced Institute for Life Sciences, Qingdao 266555, China.
| | - Huan Liu
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China; Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark.
| | - Sheng-Guo Fang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
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Matos B, Publicover SJ, Castro LFC, Esteves PJ, Fardilha M. Brain and testis: more alike than previously thought? Open Biol 2021; 11:200322. [PMID: 34062096 PMCID: PMC8169208 DOI: 10.1098/rsob.200322] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Several strands of evidence indicate the presence of marked similarities between human brain and testis. Understanding these similarities and their implications has become a topic of interest among the scientific community. Indeed, an association of intelligence with some semen quality parameters has been reported and a relation between dysfunctions of the human brain and testis has also been evident. Numerous common molecular features are evident when these tissues are compared, which is reflected in the huge number of common proteins. At the functional level, human neurons and sperm share a number of characteristics, including the importance of the exocytotic process and the presence of similar receptors and signalling pathways. The common proteins are mainly involved in exocytosis, tissue development and neuron/brain-associated biological processes. With this analysis, we conclude that human brain and testis share several biochemical characteristics which, in addition to their involvement in the speciation process, could, at least in part, be responsible for the expression of a huge number of common proteins. Nonetheless, this is an underexplored topic, and the connection between these tissues needs to be clarified, which could help to understand the dysfunctions affecting brain and testis, as well as to develop improved therapeutic strategies.
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Affiliation(s)
- Bárbara Matos
- Laboratory of Signal Transduction, Department of Medical Sciences, Institute of Biomedicine-iBiMED, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Stephen J Publicover
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Luis Filipe C Castro
- CIIMAR/CIMAR-Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal.,Department of Biology, FCUP-Faculty of Sciences, University of Porto, Porto, Portugal
| | - Pedro J Esteves
- Department of Biology, FCUP-Faculty of Sciences, University of Porto, Porto, Portugal.,CIBIO-InBIO, Research Centre in Biodiversity and Genetic Resources, Campus Agrico de Vairão, University of Porto, 4485-661 Vairão, Portugal
| | - Margarida Fardilha
- Laboratory of Signal Transduction, Department of Medical Sciences, Institute of Biomedicine-iBiMED, University of Aveiro, 3810-193 Aveiro, Portugal
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3
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Mayorga L, Altamirano K, Zanni Ruiz E, Pavarotti M. Human sperm capacitation is necessary for SNARE assembly in neurotoxin-resistant complexes. Andrology 2019; 8:442-449. [PMID: 31509646 DOI: 10.1111/andr.12706] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 08/20/2019] [Accepted: 09/02/2019] [Indexed: 11/28/2022]
Abstract
BACKGROUND Capacitation is not a well-defined process, required for the acrosome reaction triggered by physiological stimuli. In vitro, capacitation is achieved by sperm incubation in artificial media supplemented with HCO3 - , Ca2+ , and albumin. The role of capacitation in the membrane fusion machinery required for acrosomal exocytosis is not well-known. SNARE proteins are fundamental for intracellular membrane fusion and acrosomal exocytosis. We have previously shown that in capacitated spermatozoa, the fusion machinery is maintained in an inactive state until the acrosome reaction is initiated. In particular, SNARE proteins are assembled in neurotoxin-resistant complexes. OBJECTIVE This work aimed to study the dynamic changes of SNARE complexes during capacitation. MATERIALS AND METHODS The light chain of tetanus and botulinum neurotoxin has been widely used to study the configuration of SNARE proteins. For this purpose, we developed a recombinant light chain of tetanus neurotoxin linked to a polyarginine peptide. This membrane-permeant protein was able to cleave cytosolic VAMP2 (a SNARE protein required for acrosome reaction) when present in a monomeric configuration. RESULTS The results show that the VAMP2 is cleaved by the membrane-permeant tetanus neurotoxin in non-capacitated spermatozoa, indicating that, before capacitation, SNAREs are not assembled in stable toxin-resistant complexes. However, 2 h of incubation in a capacitation medium containing albumin was sufficient to render VAMP2 insensitive to the toxin. DISCUSSION We conclude that during capacitation, the SNARE proteins become engaged in stable fully assembled cis-SNARE complexes. This step is likely essential to prevent untimely activation of the membrane fusion machinery. CONCLUSION We propose that capacitation promotes the stabilization of the membrane fusion machinery required for acrosomal exocytosis in preparation for the stimulus-triggered acrosome reaction.
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Affiliation(s)
- L Mayorga
- Laboratorio de Fusión de Membranas y Exocitosis Acrosomal, Instituto de Histologia y Embriologia Mendoza Dr Mario H Burgos, Mendoza, Argentina.,Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.,Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina.,Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires, Argentina.,Laboratorio de Lípidos y Exocitosis Acrosomal, Instituto de Histologia y Embriologia Mendoza Dr Mario H Burgos, Mendoza, Argentina.,Universidad Nacional de Cuyo, Mendoza, Argentina
| | - K Altamirano
- Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires, Argentina.,Laboratorio de Lípidos y Exocitosis Acrosomal, Instituto de Histologia y Embriologia Mendoza Dr Mario H Burgos, Mendoza, Argentina.,Universidad Nacional de Cuyo, Mendoza, Argentina
| | - E Zanni Ruiz
- Laboratorio de Fusión de Membranas y Exocitosis Acrosomal, Instituto de Histologia y Embriologia Mendoza Dr Mario H Burgos, Mendoza, Argentina.,Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina.,Universidad Nacional de Cuyo, Mendoza, Argentina
| | - M Pavarotti
- Laboratorio de Fusión de Membranas y Exocitosis Acrosomal, Instituto de Histologia y Embriologia Mendoza Dr Mario H Burgos, Mendoza, Argentina.,Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires, Argentina.,Universidad Nacional de Cuyo, Mendoza, Argentina
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4
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Histological analysis and identification of spermatogenesis-related genes in 2-, 6-, and 12-month-old sheep testes. Naturwissenschaften 2017; 104:84. [DOI: 10.1007/s00114-017-1505-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 09/11/2017] [Accepted: 09/13/2017] [Indexed: 12/27/2022]
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5
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Quevedo MF, Lucchesi O, Bustos MA, Pocognoni CA, De la Iglesia PX, Tomes CN. The Rab3A-22A Chimera Prevents Sperm Exocytosis by Stabilizing Open Fusion Pores. J Biol Chem 2016; 291:23101-23111. [PMID: 27613869 DOI: 10.1074/jbc.m116.729954] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Indexed: 11/06/2022] Open
Abstract
At the final stage of exocytotis, a fusion pore opens between the plasma and a secretory vesicle membranes; typically, when the pore dilates the vesicle releases its cargo. Sperm contain a large dense-core secretory granule (the acrosome) whose contents are secreted by regulated exocytosis at fertilization. Minutes after the arrival of the triggering signal, the acrosomal and plasma membranes dock at multiple sites and fusion pores open at the contact points. It is believed that immediately afterward, fusion pores dilate spontaneously. Rab3A is an essential component of human sperm exocytotic machinery. Yet, recombinant, persistently active Rab3A halts calcium-triggered secretion when introduced after docking into streptolysin O-permeabilized cells; so does a Rab3A-22A chimera. Here, we applied functional assays, electron and confocal microscopy to show that the secretion blockage is due to the stabilization of open fusion pores. Other novel findings are that sperm SNAREs engage in α-SNAP/NSF-sensitive complexes at a post-fusion stage. Complexes are disentangled by these chaperons to achieve vesiculation and acrosomal contents release. Thus, post-fusion regulation of the pores determines their expansion and the success of the acrosome reaction.
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Affiliation(s)
- María F Quevedo
- From the IHEM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Médicas, CC56. 5500 Mendoza, Argentina
| | - Ornella Lucchesi
- From the IHEM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Médicas, CC56. 5500 Mendoza, Argentina
| | - Matías A Bustos
- From the IHEM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Médicas, CC56. 5500 Mendoza, Argentina
| | - Cristian A Pocognoni
- From the IHEM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Médicas, CC56. 5500 Mendoza, Argentina
| | - Paola X De la Iglesia
- From the IHEM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Médicas, CC56. 5500 Mendoza, Argentina
| | - Claudia N Tomes
- From the IHEM, Universidad Nacional de Cuyo, CONICET, Facultad de Ciencias Médicas, CC56. 5500 Mendoza, Argentina
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6
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Hirohashi N. Site of Mammalian Sperm Acrosome Reaction. ADVANCES IN ANATOMY EMBRYOLOGY AND CELL BIOLOGY 2016; 220:145-58. [DOI: 10.1007/978-3-319-30567-7_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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7
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Abi Nahed R, Martinez G, Escoffier J, Yassine S, Karaouzène T, Hograindleur JP, Turk J, Kokotos G, Ray PF, Bottari S, Lambeau G, Hennebicq S, Arnoult C. Progesterone-induced Acrosome Exocytosis Requires Sequential Involvement of Calcium-independent Phospholipase A2β (iPLA2β) and Group X Secreted Phospholipase A2 (sPLA2). J Biol Chem 2015; 291:3076-89. [PMID: 26655718 DOI: 10.1074/jbc.m115.677799] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Indexed: 11/06/2022] Open
Abstract
Phospholipase A2 (PLA2) activity has been shown to be involved in the sperm acrosome reaction (AR), but the molecular identity of PLA2 isoforms has remained elusive. Here, we have tested the role of two intracellular (iPLA2β and cytosolic PLA2α) and one secreted (group X) PLA2s in spontaneous and progesterone (P4)-induced AR by using a set of specific inhibitors and knock-out mice. iPLA2β is critical for spontaneous AR, whereas both iPLA2β and group X secreted PLA2 are involved in P4-induced AR. Cytosolic PLA2α is dispensable in both types of AR. P4-induced AR spreads over 30 min in the mouse, and kinetic analyses suggest the presence of different sperm subpopulations, using distinct PLA2 pathways to achieve AR. At low P4 concentration (2 μm), sperm undergoing early AR (0-5 min post-P4) rely on iPLA2β, whereas sperm undergoing late AR (20-30 min post-P4) rely on group X secreted PLA2. Moreover, the role of PLA2s in AR depends on P4 concentration, with the PLA2s being key actors at low physiological P4 concentrations (≤2 μm) but not at higher P4 concentrations (~10 μm).
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Affiliation(s)
- Roland Abi Nahed
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Guillaume Martinez
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Jessica Escoffier
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Sandra Yassine
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Thomas Karaouzène
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Jean-Pascal Hograindleur
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - John Turk
- the Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, St. Louis, Missouri 63110
| | - George Kokotos
- the Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771, Greece
| | - Pierre F Ray
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France, the Centre Hospitalier Universitaire de Grenoble, Unité Fonctionnelle de Biochimie et Génétique Moléculaire, Grenoble F-38000, France
| | - Serge Bottari
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France, the Centre Hospitalier Universitaire de Grenoble, Plate-forme de Radioanalyse, IBP, CS10217, Grenoble F-38000, France
| | - Gérard Lambeau
- the Université de Nice-Sophia Antipolis, Valbonne 06560, France, the Centre Hospitalier Universitaire de Grenoble, Centre d'AMP-CECOS, CS1021, Grenoble F-38000, France
| | - Sylviane Hennebicq
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France, the Centre Hospitalier Universitaire de Grenoble, Centre d'AMP-CECOS, CS1021, Grenoble F-38000, France
| | - Christophe Arnoult
- From the Université Grenoble Alpes, F-38000 Grenoble, France, the Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France,
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Davies KTJ, Bennett NC, Tsagkogeorga G, Rossiter SJ, Faulkes CG. Family Wide Molecular Adaptations to Underground Life in African Mole-Rats Revealed by Phylogenomic Analysis. Mol Biol Evol 2015; 32:3089-107. [PMID: 26318402 PMCID: PMC4652621 DOI: 10.1093/molbev/msv175] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During their evolutionary radiation, mammals have colonized diverse habitats. Arguably the subterranean niche is the most inhospitable of these, characterized by reduced oxygen, elevated carbon dioxide, absence of light, scarcity of food, and a substrate that is energetically costly to burrow through. Of all lineages to have transitioned to a subterranean niche, African mole-rats are one of the most successful. Much of their ecological success can be attributed to a diet of plant storage organs, which has allowed them to colonize climatically varied habitats across sub-Saharan Africa, and has probably contributed to the evolution of their diverse social systems. Yet despite their many remarkable phenotypic specializations, little is known about molecular adaptations underlying these traits. To address this, we sequenced the transcriptomes of seven mole-rat taxa, including three solitary species, and combined new sequences with existing genomic data sets. Alignments of more than 13,000 protein-coding genes encompassed, for the first time, all six genera and the full spectrum of ecological and social variation in the clade. We detected positive selection within the mole-rat clade and along ancestral branches in approximately 700 genes including loci associated with tumorigenesis, aging, morphological development, and sociality. By combining these results with gene ontology annotation and protein–protein networks, we identified several clusters of functionally related genes. This family wide analysis of molecular evolution in mole-rats has identified a suite of positively selected genes, deepening our understanding of the extreme phenotypic traits exhibited by this group.
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Affiliation(s)
- Kalina T J Davies
- School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Nigel C Bennett
- Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa
| | - Georgia Tsagkogeorga
- School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Stephen J Rossiter
- School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Christopher G Faulkes
- School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom
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9
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Romarowski A, Battistone MA, La Spina FA, Puga Molina LDC, Luque GM, Vitale AM, Cuasnicu PS, Visconti PE, Krapf D, Buffone MG. PKA-dependent phosphorylation of LIMK1 and Cofilin is essential for mouse sperm acrosomal exocytosis. Dev Biol 2015; 405:237-49. [PMID: 26169470 DOI: 10.1016/j.ydbio.2015.07.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 07/01/2015] [Accepted: 07/09/2015] [Indexed: 02/06/2023]
Abstract
Mammalian sperm must acquire their fertilizing ability after a series of biochemical modifications in the female reproductive tract collectively called capacitation to undergo acrosomal exocytosis, a process that is essential for fertilization. Actin dynamics play a central role in controlling the process of exocytosis in somatic cells as well as in sperm from several mammalian species. In somatic cells, small GTPases of the Rho family are widely known as master regulators of actin dynamics. However, the role of these proteins in sperm has not been studied in detail. In the present work we characterized the participation of small GTPases of the Rho family in the signaling pathway that leads to actin polymerization during mouse sperm capacitation. We observed that most of the proteins of this signaling cascade and their effector proteins are expressed in mouse sperm. The activation of the signaling pathways of cAMP/PKA, RhoA/C and Rac1 is essential for LIMK1 activation by phosphorylation on Threonine 508. Serine 3 of Cofilin is phosphorylated by LIMK1 during capacitation in a transiently manner. Inhibition of LIMK1 by specific inhibitors (BMS-3) resulted in lower levels of actin polymerization during capacitation and a dramatic decrease in the percentage of sperm that undergo acrosomal exocytosis. Thus, we demonstrated for the first time that the master regulators of actin dynamics in somatic cells are present and active in mouse sperm. Combining the results of our present study with other results from the literature, we have proposed a working model regarding how LIMK1 and Cofilin control acrosomal exocytosis in mouse sperm.
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Affiliation(s)
- Ana Romarowski
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - María A Battistone
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Florenza A La Spina
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Lis del C Puga Molina
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Guillermina M Luque
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Alejandra M Vitale
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Patricia S Cuasnicu
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Pablo E Visconti
- Department of Veterinary and Animal Science, Paige Labs, University of Massachusets, Amherst, MA 01003, USA
| | - Darío Krapf
- Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR), Rosario 2000 Argentina
| | - Mariano G Buffone
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
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10
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Abstract
Exocytosis is a highly regulated process that consists of multiple functionally, kinetically and/or morphologically definable stages such as recruitment, targeting, tethering and docking of secretory vesicles with the plasma membrane, priming of the fusion machinery and calcium-triggered membrane fusion. After fusion, the membrane around the secretory vesicle is incorporated into the plasma membrane and the granule releases its contents. The proteins involved in these processes belong to several highly conserved families: Rab GTPases, SNAREs (soluble NSF-attachment protein receptors), α-SNAP (α-NSF attachment protein), NSF (N-ethylmaleimide-sensitive factor), Munc13 and -18, complexins and synaptotagmins. In the present article, the molecules of exocytosis are reviewed, using human sperm as a model system. Sperm exocytosis is driven by isoforms of the same proteinaceous fusion machinery mentioned above, with their functions orchestrated in a hierarchically organized and unidirectional signalling cascade. In addition to the universal exocytosis regulator calcium, this cascade includes other second messengers such as diacylglycerol, inositol 1,4,5-trisphosphate and cAMP, as well as the enzymes that synthesize them and their target proteins. Of special interest is the cAMP-binding protein Epac (exchange protein directly activated by cAMP) due in part to its enzymatic activity towards Rap. The activation of Epac and Rap leads to a highly localized calcium signal which, together with assembly of the SNARE complex, governs the final stages of exocytosis. The source of this releasable calcium is the secretory granule itself.
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11
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Sosa CM, Pavarotti MA, Zanetti MN, Zoppino FCM, De Blas GA, Mayorga LS. Kinetics of human sperm acrosomal exocytosis. Mol Hum Reprod 2014; 21:244-54. [PMID: 25452326 DOI: 10.1093/molehr/gau110] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The acrosome reaction is a unique event in the lifespan of sperm characterized by the exocytosis of the acrosomal content and the release of hybrid vesicles formed by patches of the outer acrosomal membrane and the plasma membrane. This unique regulated exocytosis is mediated by essentially the same membrane fusion machinery present in neuroendocrine cells. However, whereas secretion in neuroendocrine cells occurs in less than a second, the acrosome reaction is normally assessed after several minutes of incubation with inducers. In this report, we measured the kinetics of human sperm exocytosis triggered by two stimuli (calcium ionophore and progesterone) by using electron microscopy and three different approaches based on the incorporation of fluorescent Pisum sativum agglutinin into the acrosome upon opening of fusion pores connecting the extracellular medium with the acrosomal lumen. The results with the different methods are consistent with a slow kinetics (t½ = 14 min). We also manipulated the system to measure different steps of the process. We observed that cytosolic calcium increased with a relatively fast kinetics (t½ = 0.1 min). In contrast, the swelling of the acrosomal granule that precedes exocytosis was a slow process (t½ = 13 min). When swelling was completed, the fusion pore opening was fast (t½ = 0.2 min). The results indicate that acrosomal swelling is the slowest step and it determines the kinetics of the acrosome reaction. After the swelling is completed, the efflux of calcium from intracellular stores triggers fusion pores opening and the release of hybrid vesicles in seconds.
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Affiliation(s)
- C M Sosa
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
| | - M A Pavarotti
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
| | - M N Zanetti
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina Present address: Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - F C M Zoppino
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina Present address: Laboratory of Oncology, Institute of Experimental Medicine and Biology of Cuyo (IMBECU - CONICET), 5500 Mendoza, Argentina
| | - G A De Blas
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
| | - L S Mayorga
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
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KIM YONA, GOO JUNSEO, KIM ILYONG, KIM JIEUN, KWAK MOONHWA, GO JUN, SHIM SUNBO, HONG JINTAE, HWANG DAEYOUN, SEONG JEKYUNG. Identification of the responsible proteins for increased selenium bioavailability in the brain of transgenic rats overexpressing selenoprotein M. Int J Mol Med 2014; 34:1688-98. [DOI: 10.3892/ijmm.2014.1945] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 09/09/2014] [Indexed: 11/06/2022] Open
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13
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Buffone MG, Hirohashi N, Gerton GL. Unresolved questions concerning mammalian sperm acrosomal exocytosis. Biol Reprod 2014; 90:112. [PMID: 24671881 DOI: 10.1095/biolreprod.114.117911] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In recent years, the study of mammalian acrosomal exocytosis has produced some major advances that challenge the long-held, general paradigms in the field. Principally, the idea that sperm must be acrosome-intact to bind to the zona pellucida of unfertilized eggs, based largely on in vitro fertilization studies of mouse oocytes denuded of the cumulus oophorus, has been overturned by experiments using state-of-the-art imaging of cumulus-intact oocytes and fertilization experiments where eggs were reinseminated by acrosome-reacted sperm recovered from the perivitelline space of zygotes. In light of these results, this minireview highlights a number of unresolved questions and emphasizes the fact that there is still much work to be done in this exciting field. Future experiments using recently advanced technologies should lead to a more complete and accurate understanding of the molecular mechanisms governing the fertilization process in mammals.
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Affiliation(s)
- Mariano G Buffone
- Instituto de Biologia y Medicina Experimental, National Research Council of Argentina (CONICET), Buenos Aires, Argentina
| | - Noritaka Hirohashi
- Oki Marine Biological Station, Education and Research Center for Biological Resources, Shimane University, Shimane, Japan
| | - George L Gerton
- Center for Research on Reproduction and Women's Health, Department of Obstetrics and Gynecology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
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Joshi CS, Khan SA, Khole VV. Regulation of acrosome reaction by Liprin α3, LAR and its ligands in mouse spermatozoa. Andrology 2013; 2:165-74. [PMID: 24327330 DOI: 10.1111/j.2047-2927.2013.00167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/01/2013] [Accepted: 11/04/2013] [Indexed: 11/30/2022]
Abstract
Zona pellucida-based induction of acrosome reaction (AR) is a popular and well-accepted hypothesis. However, this hypothesis is being challenged in recent years and it has been proposed that the cumulus cells might be the site of AR. In our previous study, we reported the presence of a synaptic protein Liprin α3 on sperm acrosome, and proposed its role in AR. This study was designed to understand the role of Liprin α3 and its interacting proteins in regulation of AR. It is observed that the presence of anti-Liprin α3 antibody inhibits the process of AR. Colocalization experiments demonstrate the coexistence of leucocyte antigen related (LAR) protein, Rab-interacting molecule (RIM) and Liprin α3 on sperm acrosome thereby completing the identification of all the members of RIM/MUNC/Rab3A/liprinα complex required for membrane fusion. This study demonstrates the effect of LAR ligands such as Syndecans, Nidogens and LAR wedge domain peptide on AR. We could see an increase in AR in presence of these ligands. On the basis of these data, we speculate that in presence of ligands or wedge peptide, LAR undergoes dimerization leading to inhibition of phosphatase activity and increase in AR. The presence of one of the ligands Syndecan-1 on cumulus cells led us to hypothesize that it is Syndecan which induces AR in vivo and thus another site of AR could lie in cumulus.
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Affiliation(s)
- C S Joshi
- Department of Gamete Immunobiology, National Institute for Research in Reproductive Health, Mumbai, India
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15
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MARCKS protein is phosphorylated and regulates calcium mobilization during human acrosomal exocytosis. PLoS One 2013; 8:e64551. [PMID: 23704996 PMCID: PMC3660367 DOI: 10.1371/journal.pone.0064551] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 04/17/2013] [Indexed: 12/01/2022] Open
Abstract
Acrosomal exocytosis is a calcium-regulated exocytosis that can be triggered by PKC activators. The involvement of PKC in acrosomal exocytosis has not been fully elucidated, and it is unknown if MARCKS, the major substrate for PKC, participates in this exocytosis. Here, we report that MARCKS is expressed in human spermatozoa and localizes to the sperm head and the tail. Calcium- and phorbol ester-triggered acrosomal exocytosis in permeabilized sperm was abrogated by different anti-MARCKS antibodies raised against two different domains, indicating that the protein participates in acrosomal exocytosis. Interestingly, an anti-phosphorylated MARCKS antibody was not able to inhibit secretion. Similar results were obtained using recombinant proteins and phospho-mutants of MARCKS effector domain (ED), indicating that phosphorylation regulates MARCKS function in acrosomal exocytosis. It is known that unphosphorylated MARCKS sequesters PIP2. This phospholipid is the precursor for IP3, which in turn triggers release of calcium from the acrosome during acrosomal exocytosis. We found that PIP2 and adenophostin, a potent IP3-receptor agonist, rescued MARCKS inhibition in permeabilized sperm, suggesting that MARCKS inhibits acrosomal exocytosis by sequestering PIP2 and, indirectly, MARCKS regulates the intracellular calcium mobilization. In non-permeabilized sperm, a permeable peptide of MARCKS ED also inhibited acrosomal exocytosis when stimulated by a natural agonist such as progesterone, and pharmacological inducers such as calcium ionophore and phorbol ester. The preincubation of human sperm with the permeable MARCKS ED abolished the increase in calcium levels caused by progesterone, demonstrating that MARCKS regulates calcium mobilization. In addition, the phosphorylation of MARCKS increased during acrosomal exocytosis stimulated by the same activators. Altogether, these results show that MARCKS is a negative modulator of the acrosomal exocytosis, probably by sequestering PIP2, and that it is phosphorylated during acrosomal exocytosis.
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Rodríguez F, Zanetti MN, Mayorga LS, Tomes CN. Munc18-1 controls SNARE protein complex assembly during human sperm acrosomal exocytosis. J Biol Chem 2012; 287:43825-39. [PMID: 23091057 DOI: 10.1074/jbc.m112.409649] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The spermatozoon is a very specialized cell capable of carrying out a limited set of functions with high efficiency. Sperm are then excellent model cells to dissect fundamental processes such as regulated exocytosis. The secretion of the single dense-core granule of mammalian spermatozoa relies on the same highly conserved molecules and goes through the same stages as exocytosis in other types of cells. In this study, we describe the presence of Munc18-1 in human sperm and show that this protein has an essential role in acrosomal exocytosis. We observed that inactivation of endogenous Munc18-1 with a specific antibody precluded the stabilization of trans-SNARE complexes and inhibited acrosomal exocytosis. Addition of recombinant Munc18-1 blocked secretion by sequestering monomeric syntaxin, an effect that was rescued by α-soluble NSF attachment protein. By electron microscopy, we observed that both the anti-Munc18-1 antibody and recombinant Munc18-1 inhibited the docking of the acrosome to the plasma membrane. In conclusion, our results indicate that Munc18-1 plays a key role in the dynamics of trans-SNARE complex assembly and/or stabilization, a process that is necessary for the docking of the outer acrosomal membrane to the plasma membrane and subsequent fusion pore opening.
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Affiliation(s)
- Facundo Rodríguez
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología-Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
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17
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Stouffs K, Vandermaelen D, Massart A, Menten B, Vergult S, Tournaye H, Lissens W. Array comparative genomic hybridization in male infertility. Hum Reprod 2012; 27:921-9. [DOI: 10.1093/humrep/der440] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Falkowski MA, Thomas DDH, Messenger SW, Martin TF, Groblewski GE. Expression, localization, and functional role for synaptotagmins in pancreatic acinar cells. Am J Physiol Gastrointest Liver Physiol 2011; 301:G306-16. [PMID: 21636530 PMCID: PMC3154608 DOI: 10.1152/ajpgi.00108.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 06/01/2011] [Indexed: 01/31/2023]
Abstract
Secretagogue-induced changes in intracellular Ca(2+) play a pivotal role in secretion in pancreatic acini yet the molecules that respond to Ca(2+) are uncertain. Zymogen granule (ZG) exocytosis is regulated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes. In nerve and endocrine cells, Ca(2+)-stimulated exocytosis is regulated by the SNARE-associated family of proteins termed synaptotagmins. This study examined a potential role for synaptotagmins in acinar secretion. RT-PCR revealed that synaptotagmin isoforms 1, 3, 6, and 7 are present in isolated acini. Immunoblotting and immunofluorescence using three different antibodies demonstrated synaptotagmin 1 immunoreactivity in apical cytoplasm and ZG fractions of acini, where it colocalized with vesicle-associated membrane protein 2. Synaptotagmin 3 immunoreactivity was detected in membrane fractions and colocalized with an endolysosomal marker. A potential functional role for synaptotagmin 1 in secretion was indicated by results that introduction of synaptotagmin 1 C2AB domain into permeabilized acini inhibited Ca(2+)-dependent exocytosis by 35%. In contrast, constructs of synaptotagmin 3 had no effect. Confirmation of these findings was achieved by incubating intact acini with an antibody specific to the intraluminal domain of synaptotagmin 1, which is externalized following exocytosis. Externalized synaptotagmin 1 was detected exclusively along the apical membrane. Treatment with CCK-8 (100 pM, 5 min) enhanced immunoreactivity by fourfold, demonstrating that synaptotagmin is inserted into the apical membrane during ZG fusion. Collectively, these data indicate that acini express synaptotagmin 1 and support that it plays a functional role in secretion whereas synaptotagmin 3 has an alternative role in endolysosomal membrane trafficking.
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Synaptotagmin IV Acts as a Multi-Functional Regulator of Ca2+-Dependent Exocytosis. Neurochem Res 2010; 36:1222-7. [DOI: 10.1007/s11064-010-0352-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 11/26/2010] [Indexed: 02/06/2023]
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20
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Xue M, Craig TK, Shin OH, Li L, Brautigam CA, Tomchick DR, Südhof TC, Rosenmund C, Rizo J. Structural and mutational analysis of functional differentiation between synaptotagmins-1 and -7. PLoS One 2010; 5. [PMID: 20824061 PMCID: PMC2932738 DOI: 10.1371/journal.pone.0012544] [Citation(s) in RCA: 25] [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: 06/14/2010] [Accepted: 08/09/2010] [Indexed: 01/16/2023] Open
Abstract
Synaptotagmins are known to mediate diverse forms of Ca2+-triggered exocytosis through their C2 domains, but the principles underlying functional differentiation among them are unclear. Synaptotagmin-1 functions as a Ca2+ sensor in neurotransmitter release at central nervous system synapses, but synaptotagmin-7 does not, and yet both isoforms act as Ca2+ sensors in chromaffin cells. To shed light into this apparent paradox, we have performed rescue experiments in neurons from synaptotagmin-1 knockout mice using a chimera that contains the synaptotagmin-1 sequence with its C2B domain replaced by the synaptotagmin-7 C2B domain (Syt1/7). Rescue was not achieved either with the WT Syt1/7 chimera or with nine mutants where residues that are distinct in synaptotagmin-7 were restored to those present in synaptotagmin-1. To investigate whether these results arise because of unique conformational features of the synaptotagmin-7 C2B domain, we determined its crystal structure at 1.44 Å resolution. The synaptotagmin-7 C2B domain structure is very similar to that of the synaptotagmin-1 C2B domain and contains three Ca2+-binding sites. Two of the Ca2+-binding sites of the synaptotagmin-7 C2B domain are also present in the synaptotagmin-1 C2B domain and have analogous ligands to those determined for the latter by NMR spectroscopy, suggesting that a discrepancy observed in a crystal structure of the synaptotagmin-1 C2B domain arose from crystal contacts. Overall, our results suggest that functional differentiation in synaptotagmins arises in part from subtle sequence changes that yield dramatic functional differences.
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Affiliation(s)
- Mingshan Xue
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Timothy K. Craig
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Ok-Ho Shin
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Liyi Li
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Chad A. Brautigam
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Diana R. Tomchick
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Thomas C. Südhof
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Molecular and Cellular Physiology, Stanford University, Palo Alto, California, United States of America
- Howard Hughes Medical Institute, Stanford University, Palo Alto, California, United States of America
| | - Christian Rosenmund
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Neuroscience Research Center, Charite-Universitätsmedizin Berlin, Berlin, Germany
- Cluster of Excellence NeuroCure, Charite-Universitätsmedizin Berlin, Berlin, Germany
- * E-mail: (CR); (JR)
| | - Josep Rizo
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (CR); (JR)
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Castillo Bennett J, Roggero CM, Mancifesta FE, Mayorga LS. Calcineurin-mediated dephosphorylation of synaptotagmin VI is necessary for acrosomal exocytosis. J Biol Chem 2010; 285:26269-78. [PMID: 20551332 DOI: 10.1074/jbc.m109.095752] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Regulated secretion is a fundamental process underlying the function of many cell types. In particular, acrosomal exocytosis in mammalian sperm is essential for egg fertilization. In general, exocytosis is initiated by a cytosolic calcium increase. In this report we show that calcium affects several factors during human sperm acrosomal exocytosis. By using an antibody that specifically recognizes synaptotagmin VI phosphorylated at the polybasic region of the C2B domain, we showed that a calcium-dependent dephosphorylation of this protein occurred at early stages of the acrosomal exocytosis in streptolysin O-permeabilized sperm. We identified the phosphatase as calcineurin and showed that the activity of this enzyme is absolutely required during the early steps of the secretory process. When added to sperm, an inhibitor-insensitive, catalytically active domain of calcineurin was able to rescue the effect of the specific calcineurin inhibitor cyclosporin A. This same domain dephosphorylated recombinant synaptotagmin VI C2B domain, validating this protein as a new substrate for calcineurin. When sperm were treated with catalytically active calcineurin before stimulation, exocytosis was inhibited, an effect that was rescued by the phosphomimetic synaptotagmin VI C2B-T418E,T419E mutant domain. These observations indicate that synaptotagmin must be dephosphorylated at a specific window of time and suggest that phosphorylated synaptotagmin has an active role at early stages of the acrosomal exocytosis.
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Affiliation(s)
- Jimena Castillo Bennett
- Instituto de Histología y Embriología, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza 5500, Argentina
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Yamazaki T, Takata N, Uemura M, Kawamura Y. Arabidopsis synaptotagmin SYT1, a type I signal-anchor protein, requires tandem C2 domains for delivery to the plasma membrane. J Biol Chem 2010; 285:23165-76. [PMID: 20498364 DOI: 10.1074/jbc.m109.084046] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The correct localization of integral membrane proteins to subcellular compartments is important for their functions. Synaptotagmin contains a single transmembrane domain that functions as a type I signal-anchor sequence in its N terminus and two calcium-binding domains (C(2)A and C(2)B) in its C terminus. Here, we demonstrate that the localization of an Arabidopsis synaptotagmin homolog, SYT1, to the plasma membrane (PM) is modulated by tandem C2 domains. An analysis of the roots of a transformant-expressing green fluorescent protein-tagged SYT1 driven by native SYT1 promoter suggested that SYT1 is synthesized in the endoplasmic reticulum, and then delivered to the PM via the exocytotic pathway. We transiently expressed a series of truncated proteins in protoplasts, and determined that tandem C(2)A-C(2)B domains were necessary for the localization of SYT1 to the PM. The PM localization of SYT1 was greatly reduced following mutation of the calcium-binding motifs of the C(2)B domain, based on sequence comparisons with other homologs, such as endomembrane-localized SYT5. The localization of SYT1 to the PM may have been required for the functional divergence that occurred in the molecular evolution of plant synaptotagmins.
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Affiliation(s)
- Tomokazu Yamazaki
- 21st Century Center of Excellence Program, Iwate University, Morioka, Iwate 020-8550, Japan
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23
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Musch MW, Arvans DL, Wang Y, Nakagawa Y, Solomaha E, Chang EB. Cyclic AMP-mediated endocytosis of intestinal epithelial NHE3 requires binding to synaptotagmin 1. Am J Physiol Gastrointest Liver Physiol 2010; 298:G203-11. [PMID: 19926819 PMCID: PMC2822502 DOI: 10.1152/ajpgi.00379.2009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The apical membrane Na(+)-H(+) exchanger (NHE)3 is regulated by cAMP-dependent phosphorylation, which inhibits its activity through membrane endocytosis. The clathrin complex adaptor protein synaptotagmin 1 (Syt 1) appears to be essential to this process, but little is known about its expression in intestinal epithelial cells or interaction with NHE3. The intestinal epithelial expression and apical location of Syt 1 were determined by Syt 1 mRNA profiling and immunolocalization. Tandem mass spectrometry was used for protein identification. Bis(sulfosuccinimidyl) suberate (BS(3)) cross linking suggested that NHE3 and Syt 1 were in a membrane complex following cAMP stimulation of Caco2BBE (Brush Border Expressions) cells. To investigate the regulation of NHE3 appearance in a Syt 1-containing membrane compartment, doxycycline-inducible hemaglutinin (HA)-tagged NHE3 was expressed in Caco2BBE cells. HA-NHE3 correctly targeted to the apical membrane, where, upon cAMP stimulation, it was internalized with a Syt 1-containing compartment. Site-directed mutagenesis of NHE3 showed that serine 605 (S605) was pivotal to NHE3 and Syt 1 association and internalization. Direct Syt 1 interaction with NHE3 was suggested by fluorescence resonance energy transfer (FRET) analysis. The physiological role of S552 was less clear. By FRET, this serine residue appeared to be involved in cAMP-induced Syt 1 binding of NHE3. However, when HA-tagged NHE3 S552A was expressed in Caco2 cells, the mutated construct was not inserted into the apical membrane. We conclude that intestinal epithelial Syt 1 plays an important role in cAMP-stimulated endocytosis of apical NHE3 through cAMP-dependent phosphorylation of S605 that is required for NHE3 and Syt 1 association.
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Affiliation(s)
| | | | - Yunwei Wang
- 1Martin Boyer Laboratories, Department of Medicine;
| | | | - Elena Solomaha
- 2Biophysical Research Core Facility, Divisions of Biological and Physical Sciences, University of Chicago, Chicago, Illinois
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Zanetti N, Mayorga LS. Acrosomal Swelling and Membrane Docking Are Required for Hybrid Vesicle Formation During the Human Sperm Acrosome Reaction1. Biol Reprod 2009; 81:396-405. [DOI: 10.1095/biolreprod.109.076166] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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25
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Li S, Qiao Y, Di Q, Le X, Zhang L, Zhang X, Zhang C, Cheng J, Zong S, Koide SS, Miao S, Wang L. Interaction of SH3P13 and DYDC1 protein: a germ cell component that regulates acrosome biogenesis during spermiogenesis. Eur J Cell Biol 2009; 88:509-20. [PMID: 19545932 DOI: 10.1016/j.ejcb.2009.05.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 04/19/2009] [Accepted: 05/05/2009] [Indexed: 01/15/2023] Open
Abstract
The N-terminal BAR domain of endophilin has unique functions, such as affecting the curvature of the lipid membrane through its lysophosphatidic acid acyltransferase activity, binding of ATP and GTP and participating in tubulating activity. We recently demonstrated that SH3P13, a BAR domain-containing protein, assists in regulating clathrin-coated vesicle traffic that is crucial for acrosome biogenesis during spermatogenesis. DYDC1 was identified in a yeast two-hybrid screen from a human testis library by using the SH3P13 BAR domain as the bait. Consistent with the expression pattern of SH3P13, DYDC1 is exclusively expressed in the brain and testis and accumulates in the acrosome area during late stage of spermiogenesis. Here, we report that DYDC1 plays a crucial role during acrosome biogenesis. This relationship has been verified by a novel approach that involves germ cell transplantation and RNA interference. We found that knockdown of endogenous Dydc1 interfered with the formation of acrosomes, and thus spermatid differentiation during mouse spermiogenesis. These data provide important insight into the crucial process of acrosome biogenesis. In addition, our approach can also be applied to study functions of other genes related to spermatogenesis in vivo.
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Affiliation(s)
- Shuchun Li
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, Tsinghua University, Beijing, China
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Oikonomopoulou I, Patel H, Watson PF, Chantler PD. Relocation of myosin and actin, kinesin and tubulin in the acrosome reaction of bovine spermatozoa. Reprod Fertil Dev 2009; 21:364-77. [PMID: 19210928 DOI: 10.1071/rd08166] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 09/22/2008] [Indexed: 01/24/2023] Open
Abstract
The mammalian acrosome reaction is a specialised exocytotic event. Although molecular motors are known to be involved in exocytosis in many cell types, their potential involvement in the acrosome reaction has remained unknown. Here, it has been shown that actin is localised within the equatorial segment and in the marginal acrosomal ridge of the heads of unreacted bull spermatozoa. Myosins IIA and IIB are found within the anterior acrosomal margins of virtually all sperm cells and, less prominently, within the equatorial segment. Tubulin was detected in the equatorial segment and around the periphery of the acrosome while kinesin was prominent in the equatorial segment. After induction of the acrosome reaction by means of the calcium ionophore A23187, the number of cells exhibiting actin fluorescence intensity in the anterior acrosomal margin decreased four-fold and those displaying equatorial segment fluorescence decreased 3.5-fold; myosin IIA immunofluorescence decreased in intensity with most spermatozoa losing equatorial staining, whereas there was little change in the distribution or intensity of myosin IIB immunofluorescence, except for approximately 20% decrease in the number of cells exhibiting acrosomal staining. Tubulin became largely undetectable within the head and kinesin staining spread rostrally over the main acrosome region. A possible sequence of events that ties in these observations of molecular motor involvement with the known participation of SNARE proteins is provided.
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Mittelsteadt T, Seifert G, Alvárez-Barón E, Steinhäuser C, Becker AJ, Schoch S. Differential mRNA expression patterns of the synaptotagmin gene family in the rodent brain. J Comp Neurol 2009; 512:514-28. [DOI: 10.1002/cne.21908] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Zhao H, Ito Y, Chappel J, Andrews NW, Teitelbaum SL, Ross FP. Synaptotagmin VII regulates bone remodeling by modulating osteoclast and osteoblast secretion. Dev Cell 2008; 14:914-25. [PMID: 18539119 DOI: 10.1016/j.devcel.2008.03.022] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Revised: 02/13/2008] [Accepted: 03/31/2008] [Indexed: 01/23/2023]
Abstract
Maintenance of bone mass and integrity requires a tight balance between resorption by osteoclasts and formation by osteoblasts. Exocytosis of functional proteins is a prerequisite for the activity of both cells. In the present study, we show that synaptotagmin VII, a calcium sensor protein that regulates exocytosis, is associated with lysosomes in osteoclasts and bone matrix protein-containing vesicles in osteoblasts. Absence of synaptotagmin VII inhibits cathepsin K secretion and formation of the ruffled border in osteoclasts and bone matrix protein deposition in osteoblasts, without affecting the differentiation of either cell. Reflecting these in vitro findings, synaptotagmin VII-deficient mice are osteopenic due to impaired bone resorption and formation. Therefore, synaptotagmin VII plays an important role in bone remodeling and homeostasis by modulating secretory pathways functionally important in osteoclasts and osteoblasts.
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Affiliation(s)
- Haibo Zhao
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Martens S, McMahon HT. Mechanisms of membrane fusion: disparate players and common principles. Nat Rev Mol Cell Biol 2008; 9:543-56. [DOI: 10.1038/nrm2417] [Citation(s) in RCA: 524] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Connell E, Giniatullina A, Lai-Kee-Him J, Tavare R, Ferrari E, Roseman A, Cojoc D, Brisson AR, Davletov B. Cross-linking of phospholipid membranes is a conserved property of calcium-sensitive synaptotagmins. J Mol Biol 2008; 380:42-50. [PMID: 18508081 PMCID: PMC2726287 DOI: 10.1016/j.jmb.2008.01.084] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 01/18/2008] [Accepted: 01/28/2008] [Indexed: 12/01/2022]
Abstract
Synaptotagmins are vesicular proteins implicated in many membrane trafficking events. They are highly conserved in evolution and the mammalian family contains 16 isoforms. We now show that the tandem C2 domains of several calcium-sensitive synaptotagmin isoforms tested, including Drosophila synaptotagmin, rapidly cross-link phospholipid membranes. In contrast to the tandem structure, individual C2 domains failed to trigger membrane cross-linking in several novel assays. Large-scale liposomal aggregation driven by tandem C2 domains in response to calcium was confirmed by the following techniques: turbidity assay, dynamic light-scattering and both confocal and negative stain electron microscopy. Firm cross-linking of membranes was evident from laser trap experiments. High-resolution cryo-electron microscopy revealed that membrane cross-linking by tandem C2 domains results in a constant distance of approximately 9 nm between the apposed membranes. Our findings show the conserved nature of this important property of synaptotagmin, demonstrate the significance of the tandem C2 domain structure and provide a plausible explanation for the accelerating effect of synaptotagmins on membrane fusion.
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Affiliation(s)
- Emma Connell
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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31
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Xu J, Mashimo T, Südhof TC. Synaptotagmin-1, -2, and -9: Ca2+ Sensors for Fast Release that Specify Distinct Presynaptic Properties in Subsets of Neurons. Neuron 2007; 54:567-81. [PMID: 17521570 DOI: 10.1016/j.neuron.2007.05.004] [Citation(s) in RCA: 207] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 04/05/2007] [Accepted: 05/07/2007] [Indexed: 10/23/2022]
Abstract
Synaptotagmin-1 and -2 are known Ca(2+) sensors for fast synchronous neurotransmitter release, but the potential Ca(2+)-sensor functions of other synaptotagmins in release remain uncharacterized. We now show that besides synaptotagmin-1 and -2, only synaptotagmin-9 (also called synaptotagmin-5) mediates fast Ca(2+) triggering of release. Release induced by the three different synaptotagmin Ca(2+) sensors exhibits distinct kinetics and apparent Ca(2+) sensitivities, suggesting that the synaptotagmin isoform expressed by a neuron determines the release properties of its synapses. Conditional knockout mice producing GFP-tagged synaptotagmin-9 revealed that synaptotagmin-9 is primarily expressed in the limbic system and striatum. Acute deletion of synaptotagmin-9 in striatal neurons severely impaired fast synchronous release without changing the size of the readily-releasable vesicle pool. These data show that in mammalian brain, only synaptotagmin-1, -2, and -9 function as Ca(2+) sensors for fast release, and that these synaptotagmins are differentially expressed to confer distinct release properties onto synapses formed by defined subsets of neurons.
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Affiliation(s)
- Jun Xu
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas TX 75390, USA
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Masztalerz A, Zeelenberg IS, Wijnands YM, de Bruijn R, Drager AM, Janssen H, Roos E. Synaptotagmin 3 deficiency in T cells impairs recycling of the chemokine receptor CXCR4 and thereby inhibits CXCL12 chemokine-induced migration. J Cell Sci 2007; 120:219-28. [PMID: 17179206 DOI: 10.1242/jcs.03328] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Synaptotagmins regulate vesicle trafficking and fusion of vesicles with membranes – processes that have been implicated in cell migration. We therefore hypothesized that synaptotagmins play a role in T-cell migration. Amongst synaptotagmins 1-11, we found synaptotagmin 3 (SYT3) to be the only one that is expressed in T cells. CXCR4-triggered migration was inhibited by antisense synaptotagmin 3 mRNA and by the isolated C2B domain, known to impair oligomerization of all synaptotagmins, but not by a C2B mutant that binds Ca2+ but does not block oligomerization. The C2B domain also blocked CXCR4-triggered actin polymerization and invasion. However, CXCR4-dependent adhesion in flow was not affected. Surprisingly, we found that little or no SYT3 is present near the plasma membrane but that it is mainly localized in multivesicular bodies, which also contained much of the CXCR4. Impaired SYT3 function blocked CXCR4 recycling and thus led to reduced surface levels of CXCR4. Migration was restored by overexpression of CXCR4. We conclude that STT3 is essential for CXCR4 recycling in T cells and thereby for the maintenance of high CXCR4 surface levels required for migration.
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Affiliation(s)
- Agnieszka Masztalerz
- Division of Cell Biology, The Netherlands Cancer Institute, 121 Plesmanlaan, 1066CX Amsterdam, The Netherlands
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Ducibella T, Matson S. Secretory mechanisms and Ca2+ signaling in gametes: similarities to regulated neuroendocrine secretion in somatic cells and involvement in emerging pathologies. Endocr Pathol 2007; 18:191-203. [PMID: 18247164 DOI: 10.1007/s12022-007-0015-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Recent studies demonstrate that regulated secretion in probably all mammalian cells, from gonadotropes to gametes, utilizes similar signaling systems, intracellular Ca(2+) regulation, Ca(2+)-dependent proteins, cytoskeletal participation, and SNARE-mediated fusion. Thus, highly specialized cells, like sperm and eggs, should no longer be considered to have evolved a cell-type specific secretory mechanism. In gametes, Ca(2+)-dependent proteins and enzymes transduce elevations of intracellular Ca(2+) into secretory events, i.e., exocytosis of the acrosome in sperm and cortical granules in the egg. Just as secretory deficiencies have clinical consequences in endocrine and exocrine cells, failure of secretion of cortical granules or the acrosome can result in failure of normal fertilization or fertilization followed by abnormal development. With the advent of human in vitro fertilization, such gamete pathologies have been recently identified and have led to new clinical procedures to achieve normal fertilization and pregnancies. A better understanding of the common Ca(2+)-dependent secretory pathways in both gametes and somatic cells should be beneficial to investigating mis-regulation in either cell type.
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Affiliation(s)
- Tom Ducibella
- Sackler School of Biomedical Sciences, Program in Cell, Molecular, and Developmental Biology, Tufts University School of Medicine, Boston, MA, 0211, USA.
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Leguia M, Conner S, Berg L, Wessel GM. Synaptotagmin I is involved in the regulation of cortical granule exocytosis in the sea urchin. Mol Reprod Dev 2006; 73:895-905. [PMID: 16572466 DOI: 10.1002/mrd.20454] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cortical granules are stimulus-dependent secretory vesicles found in the egg cortex of most vertebrates and many invertebrates. Upon fertilization, an increase in intracellular calcium levels triggers cortical granules to exocytose enzymes and structural proteins that permanently modify the extracellular surface of the egg to prevent polyspermy. Synaptotagmin is postulated to be a calcium sensor important for stimulus-dependent secretion and to test this hypothesis for cortical granule exocytosis, we identified the ortholog in two sea urchin species that is present selectively on cortical granules. Characterization by RT-PCR, in-situ RNA hybridization, Western blot and immunolocalization shows that synaptotagmin I is expressed in a manner consistent with it having a role during cortical granule secretion. We specifically tested synaptotagmin function during cortical granule exocytosis using a microinjected antibody raised against the entire cytoplasmic domain of sea urchin synaptotagmin I. The results show that synaptotagmin I is essential for normal cortical granule dynamics at fertilization in the sea urchin egg. Identification of this same protein in other developmental stages also shown here will be important for interpreting stimulus-dependent secretory events for signaling throughout embryogenesis.
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Affiliation(s)
- Mariana Leguia
- Department of Molecular and Cellular Biology & Biochemistry, Brown University, Providence, Rhode Island 02912, USA
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35
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Roggero CM, Tomes CN, De Blas GA, Castillo J, Michaut MA, Fukuda M, Mayorga LS. Protein kinase C-mediated phosphorylation of the two polybasic regions of synaptotagmin VI regulates their function in acrosomal exocytosis. Dev Biol 2006; 285:422-35. [PMID: 16111671 DOI: 10.1016/j.ydbio.2005.07.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 07/09/2005] [Accepted: 07/11/2005] [Indexed: 11/22/2022]
Abstract
We have previously reported that synaptotagmin VI is present in human sperm cells and that a recombinant protein containing the C2A and C2B domains abrogates acrosomal exocytosis in permeabilized spermatozoa, an effect that was regulated by phosphorylation. In this report, we show that each individual C2 domain blocks acrosomal exocytosis. The inhibitory effect was completely abrogated by phosphorylation of the domains with purified PKCbetaII. We found by site-directed mutagenesis that Thr418 and/or Thr419 in the polybasic region (KKKTTIK) of the C2B domain--a key region for the function of synaptotagmins--are the PKC target that regulates its inhibitory effect on acrosomal exocytosis. Similarly, we showed that Thr284 in the polybasic region of C2A (KCKLQTR) is the target for PKC-mediated phosphorylation in this domain. An antibody that specifically binds to the phosphorylated polybasic region of the C2B domain recognized endogenous phosphorylated synaptotagmin in the sperm acrosomal region. The antibody was inhibitory only at early stages of exocytosis in sperm acrosome reaction assays, and the immunolabeling decreased upon sperm stimulation, indicating that the protein is dephosphorylated during acrosomal exocytosis. Our results indicate that acrosomal exocytosis is regulated through the PKC-mediated phosphorylation of conserved threonines in the polybasic regions of synaptotagmin VI.
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Affiliation(s)
- Carlos M Roggero
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Casilla de Correo 56, 5500 Mendoza, Argentina
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36
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Branham MT, Mayorga LS, Tomes CN. Calcium-induced acrosomal exocytosis requires cAMP acting through a protein kinase A-independent, Epac-mediated pathway. J Biol Chem 2006; 281:8656-66. [PMID: 16407249 DOI: 10.1074/jbc.m508854200] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Epac, a guanine nucleotide exchange factor for the small GTPase Rap, binds to and is activated by the second messenger cAMP. In sperm, there are a number of signaling pathways required to achieve egg-fertilizing ability that depend upon an intracellular rise of cAMP. Most of these processes were thought to be mediated by cAMP-dependent protein kinases. Here we report a new dependence for the cAMP-induced acrosome reaction involving Epac. The acrosome reaction is a specialized type of regulated exocytosis leading to a massive fusion between the outer acrosomal and the plasma membranes of sperm cells. Ca2+ is the archetypical trigger of regulated exocytosis, and we show here that its effects on acrosomal release are fully mediated by cAMP. Ca2+ failed to trigger acrosomal exocytosis when intracellular cAMP was depleted by an exogenously added phosphodiesterase or when Epac was sequestered by specific blocking antibodies. The nondiscriminating dibutyryl-cAMP and the Epac-selective 8-(p-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate analogues triggered the acrosome reaction in the effective absence of extracellular Ca2+. This indicates that cAMP, via Epac activation, has the ability to drive the whole cascade of events necessary to bring exocytosis to completion, including tethering and docking of the acrosome to the plasma membrane, priming of the fusion machinery, mobilization of intravesicular Ca2+, and ultimately, bilayer mixing and fusion. cAMP-elicited exocytosis was sensitive to anti-alpha-SNAP, anti-NSF, and anti-Rab3A antibodies, to intra-acrosomal Ca2+ chelators, and to botulinum toxins but was resistant to cAMP-dependent protein kinase blockers. These experiments thus identify Epac in human sperm and evince its indispensable role downstream of Ca2+ in exocytosis.
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Affiliation(s)
- María T Branham
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología (IHEM)-Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, CC 56, Universidad Nacional de Cuyo, Mendoza 5500, Argentina
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Blas GAD, Roggero CM, Tomes CN, Mayorga LS. Dynamics of SNARE assembly and disassembly during sperm acrosomal exocytosis. PLoS Biol 2005; 3:e323. [PMID: 16131227 PMCID: PMC1197286 DOI: 10.1371/journal.pbio.0030323] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Accepted: 07/14/2005] [Indexed: 11/19/2022] Open
Abstract
The dynamics of SNARE assembly and disassembly during membrane recognition and fusion is a central issue in intracellular trafficking and regulated secretion. Exocytosis of sperm's single vesicle—the acrosome—is a synchronized, all-or-nothing process that happens only once in the life of the cell and depends on activation of both the GTP-binding protein Rab3 and of neurotoxin-sensitive SNAREs. These characteristics make acrosomal exocytosis a unique mammalian model for the study of the different phases of the membrane fusion cascade. By using a functional assay and immunofluorescence techniques in combination with neurotoxins and a photosensitive Ca2+ chelator we show that, in unactivated sperm, SNAREs are locked in heterotrimeric cis complexes. Upon Ca2+ entry into the cytoplasm, Rab3 is activated and triggers NSF/α-SNAP-dependent disassembly of cis SNARE complexes. Monomeric SNAREs in the plasma membrane and the outer acrosomal membrane are then free to reassemble in loose trans complexes that are resistant to NSF/α-SNAP and differentially sensitive to cleavage by two vesicle-associated membrane protein (VAMP)–specific neurotoxins. Ca2+ must be released from inside the acrosome to trigger the final steps of membrane fusion that require fully assembled trans SNARE complexes and synaptotagmin. Our results indicate that the unidirectional and sequential disassembly and assembly of SNARE complexes drive acrosomal exocytosis. Unidirectional and sequential disassembly and assembly of SNARE complexes drive sperm acrosomal exocytosis.
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Affiliation(s)
- Gerardo A. De Blas
- 1Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Carlos M Roggero
- 1Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Claudia N Tomes
- 1Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Luis S Mayorga
- 1Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
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Belmonte SA, López CI, Roggero CM, De Blas GA, Tomes CN, Mayorga LS. Cholesterol content regulates acrosomal exocytosis by enhancing Rab3A plasma membrane association. Dev Biol 2005; 285:393-408. [PMID: 16099449 DOI: 10.1016/j.ydbio.2005.07.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Revised: 06/08/2005] [Accepted: 07/06/2005] [Indexed: 02/01/2023]
Abstract
The acrosome is an exocytic granule that overlies the spermatozoan nucleus. In response to different stimuli, it undergoes calcium-regulated exocytosis. Freshly ejaculated mammalian sperm are not immediately capable of undergoing acrosome reaction. The acquisition of this ability is called capacitation and involves a series of still not well-characterized changes in the sperm physiology. Plasma membrane cholesterol removal is one of the sperm modifications that are associated with capacitation. However, how sterols affect acrosomal exocytosis is unknown. Here, we show that short incubations with cyclodextrin, a cholesterol removal agent, just before stimulation promote acrosomal exocytosis. Moreover, the effect was also observed in permeabilized cells stimulated with calcium, indicating that cholesterol plays a direct role in the calcium-dependent exocytosis associated with acrosome reaction. Using a photo-inhibitable calcium chelator, we show that cholesterol affects an early event of the exocytic cascade rather than the lipid bilayers mixing. Functional data indicate that one target for the cholesterol effect is Rab3A. The sterol content does not affect the Rab3A activation-deactivation cycle but regulates its membrane anchoring. Western blot analysis and immunoelectron microscopy confirmed that cholesterol efflux facilitates Rab3A association to sperm plasma membrane. Our data indicate that the cholesterol efflux occurring during capacitation optimizes the conditions for the productive assembly of the fusion machinery required for acrosome reaction.
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Affiliation(s)
- S A Belmonte
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Casilla de Correo 56, 5500 Mendoza, Argentina
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Gamboa S, Ramalho-Santos J. SNARE proteins and caveolin-1 in stallion spermatozoa: possible implications for fertility. Theriogenology 2005; 64:275-91. [PMID: 15955353 DOI: 10.1016/j.theriogenology.2004.11.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Revised: 11/25/2004] [Accepted: 11/30/2004] [Indexed: 10/25/2022]
Abstract
Proteins implicated in the "SNARE hypothesis" for membrane fusion have been characterized in the acrosome of several mammalian species, and a functional role for these proteins during the acrosome reaction has been proposed. We have investigated the presence of SNAREs in equine sperm, using semen samples obtained from stallions with varying fertility. Immunocytochemical analysis revealed that members of different SNARE families can be detected on the acrosome of equine sperm, notably in the acrosomal cap and equatorial segment. These proteins include the t-SNARE syntaxin, the v-SNARE synaptobrevin/VAMP, the calcium sensor synaptotagmin, and the ATPase NSF. Also present is caveolin-1, a component of lipid rafts. Stallions with fertility problems presented the worst quality of sperm and acrosomal membrane, and had less sperm cells stained positively for SNAREs and caveolin-1, than sperm from fertile donors (p < 0.001). Ubiquitin surface staining was also performed and it seemed to inversely correlate with stallion fertility, supporting data obtained with the negative staining technique. A male-related problem was confirmed when mares that had failed to impregnate with samples from an infertile stallion were successfully inseminated with sperm from a fertile donor. Furthermore NSF, synaptotagmin and caveolin-1 staining seemed to be useful in predicting stallion fertility, i.e. significantly more sperm cells stained positively for these proteins in samples from fertile males. Although these results need to be expanded on a larger scale, they suggest that acrosomal and surface staining of equine sperm with novel probes may constitute useful tools in predicting stallion fertility.
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Affiliation(s)
- Sandra Gamboa
- Department of Zootechnic Sciences, Agricultural School, Polytechnic Institute of Coimbra, Bencanta, 3040-316 Coimbra, Portugal
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40
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Meizel S. The sperm, a neuron with a tail: 'neuronal' receptors in mammalian sperm. Biol Rev Camb Philos Soc 2005; 79:713-32. [PMID: 15682867 DOI: 10.1017/s1464793103006407] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
A number of plasma membrane receptor types originally thought to be specific to neurons have been found in other somatic cells. More surprisingly, the mammalian sperm and neuron appear to share many of these 'neuronal' receptors. The morphology, chromosome number, genomic activity, and functions of those two cell types are as unlike as any two cells in the body, but they both achieve their highly disparate goals with the aid of a number of the same receptors. Exocytosis in neurons and sperm is essential to the functions of these cells and is strongly influenced by similar receptors. 'Neuronal' receptor types in sperm may also play a role in the control of sperm motility (a function of course not shared by neurons). This review will consider the evidence for the presence of sperm plasma membrane 'neuronal' receptors and for their significance to mammalian sperm function. The persuasiveness of the evidence varies depending on the receptor being considered, but there is strong experimental support for the presence and importance of a number of 'neuronal' receptors in sperm.
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Affiliation(s)
- Stanley Meizel
- Department of Cell Biology and Human Anatomy, University of California, Davis School of Medicine, Davis, California, USA.
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Hutt DM, Baltz JM, Ngsee JK. Synaptotagmin VI and VIII and Syntaxin 2 Are Essential for the Mouse Sperm Acrosome Reaction. J Biol Chem 2005; 280:20197-203. [PMID: 15774481 DOI: 10.1074/jbc.m412920200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sperm acrosome is a large secretory granule that undergoes calcium-stimulated exocytosis by a mechanism analogous to neuronal secretion. In neurons the core SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex, composed of syntaxin (Stx), SNAP-25, and VAMP2, mediates vesicle fusion, whereas calcium regulation is thought to be accomplished by the synaptotagmin (Syt) family, some of which exhibit calcium-dependent binding to syntaxin and SNAP-25. Sperm express Syt VI and VIII and Stx2, which are co-localized to the acrosomal compartment where they might mediate exocytosis in response to calcium influx. Therefore, we examined the calcium dependence and isoform-specific interaction of Syt and Stx. We found that Stx2 binds to Syt I, VI, and VIII in a calcium-dependent manner with EC(50) values of 175, 233, and 96 mum calcium, respectively. We also determined that the EC(50) for calcium of the acrosome reaction in streptolysin O-permeabilized sperm is 87 mum, which closely coincides with the calcium sensitivity of Stx2 and Syt VIII interaction. Consistent with this is the greater potency of recombinant Syt VIII, VI, and Stx2 compared with other isoforms in inhibiting the acrosome reaction in streptolysin O-permeabilized sperm. Similarly, introduction of Syt VIII-specific antibodies was equally effective in inhibiting the acrosome fusion. Taken together, our data suggest a critical role for Syt VIII and Stx2 in membrane fusion and acrosome reaction in the sperm.
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Affiliation(s)
- Darren M Hutt
- Ottawa Health Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1Y 4E9, Canada
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42
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Mayorga LS. More on sperm acrosomal exocytosis. Bioessays 2005; 27:232; author reply 232-3. [PMID: 15666343 DOI: 10.1002/bies.20190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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43
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Darszon A, Nishigaki T, Wood C, Treviño CL, Felix R, Beltrán C. Calcium Channels and Ca2+ Fluctuations in Sperm Physiology. INTERNATIONAL REVIEW OF CYTOLOGY 2005; 243:79-172. [PMID: 15797459 DOI: 10.1016/s0074-7696(05)43002-8] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Generating new life in animals by sexual reproduction depends on adequate communication between mature and competent male and female gametes. Ion channels are instrumental in the dialogue between sperm, its environment, and the egg. The ability of sperm to swim to the egg and fertilize it is modulated by ion permeability changes induced by environmental cues and components of the egg outer layer. Ca(2+) is probably the key messenger in this information exchange. It is therefore not surprising that different Ca(2+)-permeable channels are distinctly localized in these tiny specialized cells. New approaches to measure sperm currents, intracellular Ca(2+), membrane potential, and intracellular pH with fluorescent probes, patch-clamp recordings, sequence information, and heterologous expression are revealing how sperm channels participate in fertilization. Certain sperm ion channels are turning out to be unique, making them attractive targets for contraception and for the discovery of novel signaling complexes.
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Affiliation(s)
- Alberto Darszon
- Department of Developmental Genetics and Molecular Physiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico 62210
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Fukuda M, Kanno E, Satoh M, Saegusa C, Yamamoto A. Synaptotagmin VII Is Targeted to Dense-core Vesicles and Regulates Their Ca2+-dependent Exocytosis in PC12 Cells. J Biol Chem 2004; 279:52677-84. [PMID: 15456748 DOI: 10.1074/jbc.m409241200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It has recently been proposed that synaptotagmin (Syt) VII functions as a plasma membrane Ca2+ sensor for dense-core vesicle exocytosis in PC12 cells based on the results of transient overexpression studies using green fluorescent protein (GFP)-tagged Syt VII; however, the precise subcellular localization of Syt VII is still a matter of controversy (plasma membrane versus secretory granules). In this study we established a PC12 cell line "stably expressing" the Syt VII-GFP molecule and demonstrated by immunocytochemical and immunoelectron microscopic analyses that the Syt VII-GFP protein is localized on dense-core vesicles as well as in other intracellular membranous structures, such as the trans-Golgi network and lysosomes. Syt VII-GFP forms a complex with endogenous Syts I and IX, but not with Syt IV, and it colocalize well with Syts I and IX in the cellular processes (where dense-core vesicles are accumulated) in the PC12 cell line. We further demonstrated by an N-terminal antibody-uptake experiment that Syt VII-GFP-containing dense-core vesicles undergo Ca2+ -dependent exocytosis, the same as endogenous Syt IX-containing vesicles. Moreover, silencing of Syt VII-GFP with specific small interfering RNA dramatically reduced high KCl-dependent neuropeptide Y secretion from the stable PC12 cell line (approximately 60% of the control cells), whereas the same small interfering RNA had little effect on neuropeptide Y secretion from the wild-type PC12 cells (approximately 85-90% of the control cells), indicating that the level of endogenous expression of Syt VII molecules must be low. Our results indicate that the targeting of Syt VII-GFP molecules to specific membrane compartment(s) is affected by the transfection method (transient expression versus stable expression) and suggested that Syt VII molecule on dense-core vesicles functions as a vesicular Ca2+ sensor for exocytosis in endocrine cells.
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Affiliation(s)
- Mitsunori Fukuda
- Fukuda Initiative Research Unit, RIKEN (the Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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Tomes CN, De Blas GA, Michaut MA, Farré EV, Cherhitin O, Visconti PE, Mayorga LS. alpha-SNAP and NSF are required in a priming step during the human sperm acrosome reaction. Mol Hum Reprod 2004; 11:43-51. [PMID: 15542541 DOI: 10.1093/molehr/gah126] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The acrosome is a membrane-limited granule that overlies the nucleus of the mature spermatozoon. In response to physiological or pharmacological stimuli it undergoes a special type of Ca2+-dependent exocytosis termed the acrosome reaction (AR), which is an absolute prerequisite for fertilization. Aided by a streptolysin-O permeabilization protocol developed in our laboratory, we have previously demonstrated requirements for Rab3A, N-ethylmaleimide-sensitive factor (NSF), several soluble NSF-attachment protein receptor (SNARE) proteins, and synaptotagmin VI in the human sperm AR. Here, we show that alpha-soluble NSF-attachment protein (alpha-SNAP), a protein essential for most fusion events through its interaction with NSF and the SNARE complex, exhibits a direct role in the AR. First, the presence of alpha-SNAP is demonstrated by the Western blot of human sperm protein extracts. Immunostaining experiments reveal an acrosomal localization for this protein. Second, the Ca2+ and Rab3A-triggered ARs are inhibited by anti-alpha-SNAP antibodies. Third, bacterially expressed alpha-SNAP abolishes exocytosis in a fashion that depends on its interaction with NSF. Fourth, we show a requirement for alpha-SNAP/NSF in a prefusion step early in the exocytotic pathway, after the tethering of the acrosome to the plasma membrane and before the efflux of intra-acrosomal Ca2+. These results suggest a key role for alpha-SNAP/NSF in the AR, and strengthen our understanding of the molecular players involved in the vesicle-to-plasma membrane fusion taking place during exocytosis.
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Affiliation(s)
- C N Tomes
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología (IHEM-CONICET), Facultad de Ciencias Médicas, CC 56, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina.
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Tomes CN, Roggero CM, De Blas G, Saling PM, Mayorga LS. Requirement of protein tyrosine kinase and phosphatase activities for human sperm exocytosis. Dev Biol 2004; 265:399-415. [PMID: 14732401 DOI: 10.1016/j.ydbio.2003.09.032] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The acrosome is a membrane-limited granule that overlies the nucleus of the mature spermatozoon. In response to physiological or pharmacological stimuli, sperm undergo calcium-dependent exocytosis termed the acrosome reaction, which is an absolute prerequisite for fertilization. Protein tyrosine phosphorylation and dephosphorylation are a mechanisms by which multiple cellular events are regulated. Here we report that calcium induces tyrosine phosphorylation in streptolysin O (SLO)-permeabilized human sperm. As expected, pretreatment with tyrphostin A47-a tyrosine kinase inhibitor-abolishes the calcium effect. Interestingly, the calcium-induced increase in tyrosine phosphorylation has a functional correlate in sperm exocytosis. Masking of phosphotyrosyl groups with a specific antibody or inhibition of tyrosine kinases with genistein, tyrphostin A47, and tyrphostin A51 prevent the acrosome reaction. By reversibly sequestering intra-acrosomal calcium with a photo-inhibitable chelator, we show a requirement for protein tyrosine phosphorylation late in the exocytotic pathway, after the efflux of intra-acrosomal calcium. Both mouse and human sperm contain highly active tyrosine phosphatases. Importantly, this activity declines when sperm are incubated under capacitating conditions. Inhibition of tyrosine phosphatases with pervanadate, bis(N,N-dimethylhydroxoamido)hydroxovanadate, ethyl-3,4-dephostatin, and phenylarsine oxide prevents the acrosome reaction. Our results show that both tyrosine kinases and phosphatases play a central role in sperm exocytosis.
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Affiliation(s)
- C N Tomes
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología (IHEM-CONICET), Facultad de Ciencias Médicas, CC56, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina.
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Kitamura K, Tanaka H, Nishimune Y. Haprin, a novel haploid germ cell-specific RING finger protein involved in the acrosome reaction. J Biol Chem 2003; 278:44417-23. [PMID: 12917430 DOI: 10.1074/jbc.m304306200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The acrosome reaction (i.e. the exocytosis of the sperm vesicle) is a prerequisite for fertilization, but its molecular mechanism is largely unknown. We have identified a cDNA clone for a gene named haprin, which encodes a haploid germ cell-specific RING finger protein. This protein is a novel member of the RBCC (RING finger, B-box type zinc finger, and coiled-coil domain) motif family that has roles in several cellular processes, such as exocytosis. It is transcribed exclusively in testicular germ cells after meiotic division. Western blot and immunohistochemical analyses showed the molecular weight of Haprin protein to be Mr approximately 82,000. It was localized in the acrosomal region of elongated spermatids and mature sperm and was not present in acrosome-reacted sperm. The specific antibody against the RING finger domain of Haprin inhibited the acrosome reaction in permeabilized sperm. These results indicated that the novel RBCC protein Haprin plays a key role in the acrosome reaction and fertilization.
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Affiliation(s)
- Kouichi Kitamura
- Department of Science for Laboratory Animal Experimentation, Research Institute for Microbial Disease, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Fukuda M. Molecular cloning and characterization of human, rat, and mouse synaptotagmin XV. Biochem Biophys Res Commun 2003; 306:64-71. [PMID: 12788067 DOI: 10.1016/s0006-291x(03)00911-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Synaptotagmin (Syt) constitutes a large family of putative membrane trafficking proteins that share a short extracellular domain, a single N-terminal transmembrane domain, and C-terminal tandem C2 domains. In this study, I identified and characterized a novel member of the Syt family (named Syt XV-a) in the mouse, the rat, and humans. Although Syt XV-a protein has a short hydrophobic region at the very end of the N terminus (i.e., lacks a putative extracellular domain), biochemical and cellular analyses have indicated that the short hydrophobic region (amino acids 5-22) is sufficient for producing type I membrane topology in cultured cells, the same as in other Syt family proteins. Unlike other Syt isoforms, however, the mouse and human Syt XV have an alternative splicing isoform that lacks the C-terminal portion of the C2B domain (named Syt XV-b). Since the expression of Syt XV-a/b mRNA was mainly found in non-neuronal tissues (e.g., lung and testis) and Syt XV-a C2 domains lack Ca(2+)-dependent phospholipid binding activity, Syt XV-a is classified as a non-neuronal, Ca(2+)-independent Syt.
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Affiliation(s)
- Mitsunori Fukuda
- Fukuda Initiative Research Unit, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, 351-0198, Saitama, Japan.
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Redecker P, Kreutz MR, Bockmann J, Gundelfinger ED, Boeckers TM. Brain synaptic junctional proteins at the acrosome of rat testicular germ cells. J Histochem Cytochem 2003; 51:809-19. [PMID: 12754292 DOI: 10.1177/002215540305100612] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Proteins of the presynaptic exocytic machinery have been found associated with the acrosome of male germ cells, suggesting that the sperm acrosome reaction and neurotransmission at chemical synapses may share some common mechanisms. To substantiate this hypothesis, we studied the expression and ultrastructural localization of prominent pre- and postsynaptic protein components in rat testis. The presynaptic membrane trafficking proteins SV2 and complexin, the vesicular amino acid transporters VGLUT and VIAAT, the postsynaptic scaffolding protein ProSAP/Shank, and the postsynaptic calcium-sensor protein caldendrin, could be identified in germ line cells. Immunogold electron microscopy revealed an association of these proteins with the acrosome. In addition, evidence was obtained for the expression of the plasmalemmal glutamate transporters GLT1 and GLAST in rat sperm. The novel finding that not only presynaptic proteins, which are believed to be involved in membrane fusion processes, but also postsynaptic elements are present at the acrosome sheds new light on its structural organization. Moreover, our data point to a possible role for neuroactive amino acids in reproductive physiology.
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Affiliation(s)
- Peter Redecker
- Department of Anatomy 1, Medical School of Hannover, Hannover, Germany.
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Ramalho-Santos J, Schatten G, Moreno RD. Control of membrane fusion during spermiogenesis and the acrosome reaction. Biol Reprod 2003; 67:1043-51. [PMID: 12297516 DOI: 10.1095/biolreprod67.4.1043] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Membrane fusion is important to reproduction because it occurs in several steps during the process of fertilization. Many events of intracellular trafficking occur during both spermiogenesis and oogenesis. The acrosome reaction, a key feature during mammalian fertilization, is a secretory event involving the specific fusion of the outer acrosomal membrane and the sperm plasma membrane overlaying the principal piece of the acrosome. Once the sperm has crossed the zona pellucida, the gametes fuse, but in the case of the sperm this process takes place through a specific membrane domain in the head, the equatorial segment. The cortical reaction, a process that prevents polyspermy, involves the exocytosis of the cortical granules to the extracellular milieu. In lower vertebrates, the formation of the zygotic nucleus involves the fusion (syngamia) of the male pronucleus with the female pronucleus. Other undiscovered membrane trafficking processes may also be relevant for the formation of the zygotic centrosome or other zygotic structures. In this review, we focus on the recent discovery of molecular machinery components involved in intracellular trafficking during mammalian spermiogenesis, notably related to acrosome biogenesis. We also extend our discussion to the molecular mechanism of membrane fusion during the acrosome reaction. The data available so far suggest that proteins participating in the intracellular trafficking events leading to the formation of the acrosome during mammalian spermiogenesis are also involved in controlling the acrosome reaction during fertilization.
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Affiliation(s)
- João Ramalho-Santos
- Unit of Reproduction and Development, Physiology Department, Pontifical Catholic University of Chile, 340-213 Santiago, Chile
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