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Tsarouhas V, Liu D, Tsikala G, Engström Y, Strigini M, Samakovlis C. A surfactant lipid layer of endosomal membranes facilitates airway gas filling in Drosophila. Curr Biol 2023; 33:5132-5146.e5. [PMID: 37992718 DOI: 10.1016/j.cub.2023.10.058] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 09/14/2023] [Accepted: 10/26/2023] [Indexed: 11/24/2023]
Abstract
The mechanisms underlying the construction of an air-liquid interface in respiratory organs remain elusive. Here, we use live imaging and genetic analysis to describe the morphogenetic events generating an extracellular lipid lining of the Drosophila airways required for their gas filing and animal survival. We show that sequential Rab39/Syx1A/Syt1-mediated secretion of lysosomal acid sphingomyelinase (Drosophila ASM [dASM]) and Rab11/35/Syx1A/Rop-dependent exosomal secretion provides distinct components for lipid film assembly. Tracheal inactivation of Rab11 or Rab35 or loss of Rop results in intracellular accumulation of exosomal, multi-vesicular body (MVB)-derived vesicles. On the other hand, loss of dASM or Rab39 causes luminal bubble-like accumulations of exosomal membranes and liquid retention in the airways. Inactivation of the exosomal secretion in dASM mutants counteracts this phenotype, arguing that the exosomal secretion provides the lipid vesicles and that secreted lysosomal dASM organizes them into a continuous film. Our results reveal the coordinated functions of extracellular vesicle and lysosomal secretions in generating a lipid layer crucial for airway gas filling and survival.
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Affiliation(s)
- Vasilios Tsarouhas
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden; Science for Life Laboratory, SciLifeLab, 171 65 Stockholm, Sweden.
| | - Dan Liu
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden
| | - Georgia Tsikala
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden; IMBB, 70013 Heraklion, Crete, Greece
| | - Ylva Engström
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden
| | | | - Christos Samakovlis
- Stockholm University, Department of Molecular Biosciences, The Wenner-Gren Institute, 10691 Stockholm, Sweden; Science for Life Laboratory, SciLifeLab, 171 65 Stockholm, Sweden; ECCPS, Justus Liebig University of Giessen, 35390 Giessen, Germany.
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2
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Pinheiro AS, Tsarouhas V, Senti KA, Arefin B, Samakovlis C. Scavenger receptor endocytosis controls apical membrane morphogenesis in the Drosophila airways. eLife 2023; 12:e84974. [PMID: 37706489 PMCID: PMC10564452 DOI: 10.7554/elife.84974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 09/13/2023] [Indexed: 09/15/2023] Open
Abstract
The acquisition of distinct branch sizes and shapes is a central aspect in tubular organ morphogenesis and function. In the Drosophila airway tree, the interplay of apical extracellular matrix (ECM) components with the underlying membrane and cytoskeleton controls tube elongation, but the link between ECM composition with apical membrane morphogenesis and tube size regulation is elusive. Here, we characterized Emp (epithelial membrane protein), a Drosophila CD36 homolog belonging to the scavenger receptor class B protein family. emp mutant embryos fail to internalize the luminal chitin deacetylases Serp and Verm at the final stages of airway maturation and die at hatching with liquid filled airways. Emp localizes in apical epithelial membranes and shows cargo selectivity for LDLr-domain containing proteins. emp mutants also display over elongated tracheal tubes with increased levels of the apical proteins Crb, DE-cad, and phosphorylated Src (p-Src). We show that Emp associates with and organizes the βH-Spectrin cytoskeleton and is itself confined by apical F-actin bundles. Overexpression or loss of its cargo protein Serp lead to abnormal apical accumulations of Emp and perturbations in p-Src levels. We propose that during morphogenesis, Emp senses and responds to luminal cargo levels by initiating apical membrane endocytosis along the longitudinal tube axis and thereby restricts airway elongation.
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Affiliation(s)
- Ana Sofia Pinheiro
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholmSweden
| | - Vasilios Tsarouhas
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholmSweden
| | - Kirsten André Senti
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholmSweden
- IMBA – Institute of Molecular Biotechnology, Austrian Academy of SciencesViennaAustria
| | - Badrul Arefin
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholmSweden
- Sahlgrenska Academy, Gothenburg UniversityGothenburgSweden
| | - Christos Samakovlis
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholmSweden
- Cardiopulmonary Institute, Justus Liebig University of GiessenGiessenGermany
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Zou W, Li G, Jian L, Qian J, Liu Y, Zhao J. Arabidopsis SMC6A and SMC6B have redundant function in seed and gametophyte development. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:4871-4887. [PMID: 33909904 DOI: 10.1093/jxb/erab181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 04/25/2021] [Indexed: 05/21/2023]
Abstract
Reproductive development is a crucial process during plant growth. The structural maintenance of chromosome (SMC) 5/6 complex has been studied in various species. However, there are few studies on the biological function of SMC6 in plant development, especially during reproduction. In this study, knocking out of both AtSMC6A and AtSMC6B led to severe defects in Arabidopsis seed development, and expression of AtSMC6A or AtSMC6B could completely restore seed abortion in the smc6a-/-smc6b-/-double mutant. Knocking down AtSMC6A in the smc6b-/- mutant led to defects in female and male development and decreased fertility. The double mutation also resulted in loss of cell viability, and caused embryo and endosperm cell death through vacuolar cell death and necrosis. Furthermore, the expression of genes involved in embryo patterning, endosperm cellularisation, DNA damage repair, cell cycle regulation, and DNA replication were significantly changed in the albino seeds of the double mutant. Moreover, we found that the SMC5/6 complex may participate in the SOG1 (SUPPRESSOR OF GAMMA RESPONSE1)-dependent DNA damage repair pathway. These findings suggest that both AtSMC6A and AtSMC6B are functionally redundant and play important roles in seed and gametophyte development through maintaining chromosome stability in Arabidopsis.
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Affiliation(s)
- Wenxuan Zou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Gang Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Liufang Jian
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jie Qian
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yantong Liu
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jie Zhao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
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Atkins A, Xu MJ, Li M, Rogers NP, Pryzhkova MV, Jordan PW. SMC5/6 is required for replication fork stability and faithful chromosome segregation during neurogenesis. eLife 2020; 9:e61171. [PMID: 33200984 PMCID: PMC7723410 DOI: 10.7554/elife.61171] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 11/16/2020] [Indexed: 12/21/2022] Open
Abstract
Mutations of SMC5/6 components cause developmental defects, including primary microcephaly. To model neurodevelopmental defects, we engineered a mouse wherein Smc5 is conditionally knocked out (cKO) in the developing neocortex. Smc5 cKO mice exhibited neurodevelopmental defects due to neural progenitor cell (NPC) apoptosis, which led to reduction in cortical layer neurons. Smc5 cKO NPCs formed DNA bridges during mitosis and underwent chromosome missegregation. SMC5/6 depletion triggers a CHEK2-p53 DNA damage response, as concomitant deletion of the Trp53 tumor suppressor or Chek2 DNA damage checkpoint kinase rescued Smc5 cKO neurodevelopmental defects. Further assessment using Smc5 cKO and auxin-inducible degron systems demonstrated that absence of SMC5/6 leads to DNA replication stress at late-replicating regions such as pericentromeric heterochromatin. In summary, SMC5/6 is important for completion of DNA replication prior to entering mitosis, which ensures accurate chromosome segregation. Thus, SMC5/6 functions are critical in highly proliferative stem cells during organism development.
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Affiliation(s)
- Alisa Atkins
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Michelle J Xu
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Maggie Li
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Nathaniel P Rogers
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Marina V Pryzhkova
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
| | - Philip W Jordan
- Biochemistry and Molecular Biology Department, Johns Hopkins University Bloomberg School of Public HealthBaltimoreUnited States
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Li G, Zou W, Jian L, Qian J, Zhao J. AtNSE1 and AtNSE3 are required for embryo pattern formation and maintenance of cell viability during Arabidopsis embryogenesis. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:6229-6244. [PMID: 31408172 PMCID: PMC6859727 DOI: 10.1093/jxb/erz373] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 08/06/2019] [Indexed: 05/30/2023]
Abstract
Embryogenesis is an essential process during seed development in higher plants. It has previously been shown that mutation of the Arabidopsis non-SMC element genes AtNSE1 or AtNSE3 leads to early embryo abortion, and their proteins can interact with each other directly. However, the crucial regions of these proteins in this interaction and how the proteins are cytologically involved in Arabidopsis embryo development are unknown. In this study, we found that the C-terminal including the Ring-like motif of AtNSE1 can interact with the N-terminal of AtNSE3, and only the Ring-like motif is essential for binding with three α motifs of AtNSE2 (homologous to AtMMS21). Using genetic assays and by analysing molecular markers of cell fate decisions (STM, WOX5, and WOX8) in mutant nse1 and nse3 embryos, we found that AtNSE1 and AtNSE3 work non-redundantly in early embryo development, and that differentiation of the apical meristem and the hypophysis fails in the mutants, which have disrupted auxin transportation and responses. However, the upper cells of the suspensor in the mutants seem to have proper embryo cell identity. Cytological examination showed that cell death occurred from the early embryo stage, and that vacuolar programmed cell death and necrosis in the nse1 and nse3 mutant embryos led to ovule abortion. Thus, AtNSE1 and AtNSE3 are essential for maintaining cell viability and growth during early embryogenesis. Our results improve our understanding of the functions of SMC5/6 complex in early embryogenesis in Arabidopsis.
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Affiliation(s)
- Gang Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Wenxuan Zou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Liufang Jian
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jie Qian
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jie Zhao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
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Bogolyubov DS. Karyosphere (Karyosome): A Peculiar Structure of the Oocyte Nucleus. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 337:1-48. [PMID: 29551157 DOI: 10.1016/bs.ircmb.2017.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The karyosphere, aka the karyosome, is a meiosis-specific structure that represents a "knot" of condensed chromosomes joined together in a limited volume of the oocyte nucleus. The karyosphere is an evolutionarily conserved but morphologically rather "multifaceted" structure. It forms at the diplotene stage of meiotic prophase in many animals, from hydra and Drosophila to human. Karyosphere formation is generally linked with transcriptional silencing of the genome. It is believed that karyosphere/karyosome is a prerequisite for proper completion of meiotic divisions and further development. Here, a brief review on the karyosphere features in some invertebrates and vertebrates is provided. Special emphasis is made on terminology, since current discrepancies in this field may lead to confusions. In particular, it is proposed to distinguish the karyosphere with a capsule and the karyosome (a karyosphere devoid of a capsule). The "inverted" karyospheres are also considered, in which the chromosomes situate externally to an extrachromosomal structure (e.g., in human oocytes).
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Affiliation(s)
- Dmitry S Bogolyubov
- Institute of Cytology of the Russian Academy of Science, St. Petersburg, Russia.
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Hwang G, Sun F, O'Brien M, Eppig JJ, Handel MA, Jordan PW. SMC5/6 is required for the formation of segregation-competent bivalent chromosomes during meiosis I in mouse oocytes. Development 2017; 144:1648-1660. [PMID: 28302748 PMCID: PMC5450844 DOI: 10.1242/dev.145607] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 03/07/2017] [Indexed: 01/11/2023]
Abstract
SMC complexes include three major classes: cohesin, condensin and SMC5/6. However, the localization pattern and genetic requirements for the SMC5/6 complex during mammalian oogenesis have not previously been examined. In mouse oocytes, the SMC5/6 complex is enriched at the pericentromeric heterochromatin, and also localizes along chromosome arms during meiosis. The infertility phenotypes of females with a Zp3-Cre-driven conditional knockout (cKO) of Smc5 demonstrated that maternally expressed SMC5 protein is essential for early embryogenesis. Interestingly, protein levels of SMC5/6 complex components in oocytes decline as wild-type females age. When SMC5/6 complexes were completely absent in oocytes during meiotic resumption, homologous chromosomes failed to segregate accurately during meiosis I. Despite what appears to be an inability to resolve concatenation between chromosomes during meiosis, localization of topoisomerase IIα to bivalents was not affected; however, localization of condensin along the chromosome axes was perturbed. Taken together, these data demonstrate that the SMC5/6 complex is essential for the formation of segregation-competent bivalents during meiosis I, and findings suggest that age-dependent depletion of the SMC5/6 complex in oocytes could contribute to increased incidence of oocyte aneuploidy and spontaneous abortion in aging females.
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Affiliation(s)
- Grace Hwang
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Fengyun Sun
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | | | - John J Eppig
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | | | - Philip W Jordan
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
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