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Sandhu A, Lyu X, Wan X, Meng X, Tang NH, Gonzalez G, Syed IN, Chen L, Jin Y, Chisholm AD. The microtubule regulator EFA-6 forms spatially restricted cortical foci dependent on its intrinsically disordered region and interactions with tubulins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.14.588158. [PMID: 38645057 PMCID: PMC11030407 DOI: 10.1101/2024.04.14.588158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Microtubules (MTs) are dynamic components of the cytoskeleton and play essential roles in morphogenesis and maintenance of tissue and cell integrity. Despite recent advances in understanding MT ultrastructure, organization, and growth control, how cells regulate MT organization at the cell cortex remains poorly understood. The EFA-6/EFA6 proteins are recently identified membrane-associated proteins that inhibit cortical MT dynamics. Here, combining visualization of endogenously tagged C. elegans EFA-6 with genetic screening, we uncovered tubulin-dependent regulation of EFA-6 patterning. In the mature epidermal epithelium, EFA-6 forms punctate foci in specific regions of the apical cortex, dependent on its intrinsically disordered region (IDR). We further show the EFA-6 IDR is sufficient to form biomolecular condensates in vitro. In screens for mutants with altered GFP::EFA-6 localization, we identified a novel gain-of-function (gf) mutation in an α-tubulin tba-1 that induces ectopic EFA-6 foci in multiple cell types. tba-1(gf) animals exhibit temperature-sensitive embryonic lethality, which is partially suppressed by efa-6(lf), indicating the interaction between tubulins and EFA-6 is important for normal development. TBA-1(gf) shows reduced incorporation into filamentous MTs but has otherwise mild effects on cellular MT organization. The ability of TBA-1(gf) to trigger ectopic EFA-6 foci formation requires β-tubulin TBB-2 and the chaperon EVL-20/Arl2. The tba-1(gf)-induced EFA-6 foci display slower turnover, contain the MT-associated protein TAC-1/TACC, and require the EFA-6 MTED. Our results reveal a novel crosstalk between cellular tubulins and cortical MT regulators in vivo.
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Affiliation(s)
- Anjali Sandhu
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, CA 92093 USA
| | - Xiaohui Lyu
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, CA 92093 USA
| | - Xinghaoyun Wan
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, CA 92093 USA
| | - Xuefeng Meng
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, CA 92093 USA
| | - Ngang Heok Tang
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, CA 92093 USA
| | - Gilberto Gonzalez
- Barshop Institute for Longevity and Aging Studies, Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Ishana N. Syed
- Barshop Institute for Longevity and Aging Studies, Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Lizhen Chen
- Barshop Institute for Longevity and Aging Studies, Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Yishi Jin
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, CA 92093 USA
| | - Andrew D. Chisholm
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, CA 92093 USA
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, CA 92093 USA
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Li X, Li C, Zhang W, Wang Y, Qian P, Huang H. Inflammation and aging: signaling pathways and intervention therapies. Signal Transduct Target Ther 2023; 8:239. [PMID: 37291105 PMCID: PMC10248351 DOI: 10.1038/s41392-023-01502-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 89.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 04/26/2023] [Accepted: 05/15/2023] [Indexed: 06/10/2023] Open
Abstract
Aging is characterized by systemic chronic inflammation, which is accompanied by cellular senescence, immunosenescence, organ dysfunction, and age-related diseases. Given the multidimensional complexity of aging, there is an urgent need for a systematic organization of inflammaging through dimensionality reduction. Factors secreted by senescent cells, known as the senescence-associated secretory phenotype (SASP), promote chronic inflammation and can induce senescence in normal cells. At the same time, chronic inflammation accelerates the senescence of immune cells, resulting in weakened immune function and an inability to clear senescent cells and inflammatory factors, which creates a vicious cycle of inflammation and senescence. Persistently elevated inflammation levels in organs such as the bone marrow, liver, and lungs cannot be eliminated in time, leading to organ damage and aging-related diseases. Therefore, inflammation has been recognized as an endogenous factor in aging, and the elimination of inflammation could be a potential strategy for anti-aging. Here we discuss inflammaging at the molecular, cellular, organ, and disease levels, and review current aging models, the implications of cutting-edge single cell technologies, as well as anti-aging strategies. Since preventing and alleviating aging-related diseases and improving the overall quality of life are the ultimate goals of aging research, our review highlights the critical features and potential mechanisms of inflammation and aging, along with the latest developments and future directions in aging research, providing a theoretical foundation for novel and practical anti-aging strategies.
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Affiliation(s)
- Xia Li
- Bone Marrow Transplantation Center, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- Liangzhu Laboratory, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, 311121, China
- Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, 310058, China
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, 310058, China
| | - Chentao Li
- Liangzhu Laboratory, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, 311121, China
- Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Zhejiang University, Haining, China
| | - Wanying Zhang
- Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Zhejiang University, Haining, China
| | - Yanan Wang
- Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Zhejiang University, Haining, China
| | - Pengxu Qian
- Liangzhu Laboratory, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, 311121, China.
- Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, 310058, China.
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, 310058, China.
- Center for Stem Cell and Regenerative Medicine and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China.
| | - He Huang
- Bone Marrow Transplantation Center, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China.
- Liangzhu Laboratory, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, 311121, China.
- Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, 310058, China.
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, 310058, China.
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Steers NJ, Gupta Y, D’Agati VD, Lim TY, DeMaria N, Mo A, Liang J, Stevens KO, Ahram DF, Lam WY, Gagea M, Nagarajan L, Sanna-Cherchi S, Gharavi AG. GWAS in Mice Maps Susceptibility to HIV-Associated Nephropathy to the Ssbp2 Locus. J Am Soc Nephrol 2022; 33:108-120. [PMID: 34893534 PMCID: PMC8763192 DOI: 10.1681/asn.2021040543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 09/27/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND To gain insight into the pathogenesis of collapsing glomerulopathy, a rare form of FSGS that often arises in the setting of viral infections, we performed a genome-wide association study (GWAS) among inbred mouse strains using a murine model of HIV-1 associated nephropathy (HIVAN). METHODS We first generated F1 hybrids between HIV-1 transgenic mice on the FVB/NJ background and 20 inbred laboratory strains. Analysis of histology, BUN, and urinary NGAL demonstrated marked phenotypic variation among the transgenic F1 hybrids, providing strong evidence for host genetic factors in the predisposition to nephropathy. A GWAS in 365 transgenic F1 hybrids generated from these 20 inbred strains was performed. RESULTS We identified a genome-wide significant locus on chromosome 13-C3 and multiple additional suggestive loci. Crossannotation of the Chr. 13 locus, including single-cell transcriptomic analysis of wildtype and HIV-1 transgenic mouse kidneys, nominated Ssbp2 as the most likely candidate gene. Ssbp2 is highly expressed in podocytes, encodes a transcriptional cofactor that interacts with LDB1 and LMX1B, which are both previously implicated in FSGS. Consistent with these data, older Ssbp2 null mice spontaneously develop glomerulosclerosis, tubular casts, interstitial fibrosis, and inflammation, similar to the HIVAN mouse model. CONCLUSIONS These findings demonstrate the utility of GWAS in mice to uncover host genetic factors for rare kidney traits and suggest Ssbp2 as susceptibility gene for HIVAN, potentially acting via the LDB1-LMX1B transcriptional network.
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Affiliation(s)
- Nicholas J. Steers
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Yask Gupta
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Vivette D. D’Agati
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, New York
| | - Tze Y. Lim
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Natalia DeMaria
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Anna Mo
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Judy Liang
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Kelsey O. Stevens
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Dina F. Ahram
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Wan Yee Lam
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Mihai Gagea
- Department of Veterinary Medicine and Surgery, University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Lalitha Nagarajan
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Simone Sanna-Cherchi
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Ali G. Gharavi
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
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PIM-Related Kinases Selectively Regulate Olfactory Sensations in Caenorhabditis elegans. eNeuro 2019; 6:ENEURO.0003-19.2019. [PMID: 31387876 PMCID: PMC6709224 DOI: 10.1523/eneuro.0003-19.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 07/12/2019] [Accepted: 07/18/2019] [Indexed: 11/21/2022] Open
Abstract
The mammalian PIM family of serine/threonine kinases regulate several cellular functions, such as cell survival and motility. Because PIM expression is observed in sensory organs, such as olfactory epithelium, we now wanted to explore the physiological roles of PIM kinases there. As our model organism, we used the Caenorhabditis elegans nematodes, which express two PIM-related kinases, PRK-1 and PRK-2. We demonstrated PRKs to be true PIM orthologs with similar substrate specificity as well as sensitivity to PIM-inhibitory compounds. When we analyzed the effects of pan-PIM inhibitors on C. elegans sensory functions, we observed that PRK activity is selectively required to support olfactory sensations to volatile repellents and attractants sensed by AWB and AWCON neurons, respectively, but is dispensable for gustatory sensations. Analyses of prk-deficient mutant strains confirmed these findings and suggested that PRK-1, but not PRK-2 is responsible for the observed effects on olfaction. This regulatory role of PRK-1 is further supported by its observed expression in the head and tail neurons, including AWB and AWC neurons. Based on the evolutionary conservation of PIM-related kinases, our data may have implications in regulation of also mammalian olfaction.
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Crawley O, Giles AC, Desbois M, Kashyap S, Birnbaum R, Grill B. A MIG-15/JNK-1 MAP kinase cascade opposes RPM-1 signaling in synapse formation and learning. PLoS Genet 2017; 13:e1007095. [PMID: 29228003 PMCID: PMC5754208 DOI: 10.1371/journal.pgen.1007095] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 01/04/2018] [Accepted: 11/01/2017] [Indexed: 12/18/2022] Open
Abstract
The Pam/Highwire/RPM-1 (PHR) proteins are conserved intracellular signaling hubs that regulate synapse formation and axon termination. The C. elegans PHR protein, called RPM-1, acts as a ubiquitin ligase to inhibit the DLK-1 and MLK-1 MAP kinase pathways. We have identified several kinases that are likely to form a new MAP kinase pathway that suppresses synapse formation defects, but not axon termination defects, in the mechanosensory neurons of rpm-1 mutants. This pathway includes: MIG-15 (MAP4K), NSY-1 (MAP3K), JKK-1 (MAP2K) and JNK-1 (MAPK). Transgenic overexpression of kinases in the MIG-15/JNK-1 pathway is sufficient to impair synapse formation in wild-type animals. The MIG-15/JNK-1 pathway functions cell autonomously in the mechanosensory neurons, and these kinases localize to presynaptic terminals providing further evidence of a role in synapse development. Loss of MIG-15/JNK-1 signaling also suppresses defects in habituation to repeated mechanical stimuli in rpm-1 mutants, a behavioral deficit that is likely to arise from impaired glutamatergic synapse formation. Interestingly, habituation results are consistent with the MIG-15/JNK-1 pathway functioning as a parallel opposing pathway to RPM-1. These findings indicate the MIG-15/JNK-1 pathway can restrict both glutamatergic synapse formation and short-term learning.
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Affiliation(s)
- Oliver Crawley
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, United States of America
| | - Andrew C. Giles
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, United States of America
| | - Muriel Desbois
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, United States of America
| | - Sudhanva Kashyap
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, United States of America
| | - Rayna Birnbaum
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL, United States of America
| | - Brock Grill
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, United States of America
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6
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Phosphatidylserine save-me signals drive functional recovery of severed axons in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2017; 114:E10196-E10205. [PMID: 29109263 PMCID: PMC5703272 DOI: 10.1073/pnas.1703807114] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Nervous system injury can cause lifelong disability, because repair rarely leads to reconnection with the target tissue. In the nematode Caenorhabditis elegans and in several other species, regeneration can proceed through a mechanism of axonal fusion, whereby regrowing axons reconnect and fuse with their own separated fragments, rapidly and efficiently restoring the original axonal tract. We have found that the process of axonal fusion restores full function to damaged neurons. In addition, we show that injury-induced changes to the axonal membrane that result in exposure of lipid “save-me” signals mediate the level of axonal fusion. Thus, our results establish axonal fusion as a complete regenerative mechanism that can be modulated by changing the level of save-me signals exposed after injury. Functional regeneration after axonal injury requires transected axons to regrow and reestablish connection with their original target tissue. The spontaneous regenerative mechanism known as axonal fusion provides a highly efficient means of achieving targeted reconnection, as a regrowing axon is able to recognize and fuse with its own detached axon segment, thereby rapidly reestablishing the original axonal tract. Here, we use behavioral assays and fluorescent reporters to show that axonal fusion enables full recovery of function after axotomy of Caenorhabditis elegans mechanosensory neurons. Furthermore, we reveal that the phospholipid phosphatidylserine, which becomes exposed on the damaged axon to function as a “save-me” signal, defines the level of axonal fusion. We also show that successful axonal fusion correlates with the regrowth potential and branching of the proximal fragment and with the retraction length and degeneration of the separated segment. Finally, we identify discrete axonal domains that vary in their propensity to regrow through fusion and show that the level of axonal fusion can be genetically modulated. Taken together, our results reveal that axonal fusion restores full function to injured neurons, is dependent on exposure of phospholipid signals, and is achieved through the balance between regenerative potential and level of degeneration.
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7
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Hsu JM, Chen CH, Chen YC, McDonald KL, Gurling M, Lee A, Garriga G, Pan CL. Genetic analysis of a novel tubulin mutation that redirects synaptic vesicle targeting and causes neurite degeneration in C. elegans. PLoS Genet 2014; 10:e1004715. [PMID: 25392990 PMCID: PMC4230729 DOI: 10.1371/journal.pgen.1004715] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 08/27/2014] [Indexed: 11/24/2022] Open
Abstract
Neuronal cargos are differentially targeted to either axons or dendrites, and this polarized cargo targeting critically depends on the interaction between microtubules and molecular motors. From a forward mutagenesis screen, we identified a gain-of-function mutation in the C. elegans α-tubulin gene mec-12 that triggered synaptic vesicle mistargeting, neurite swelling and neurodegeneration in the touch receptor neurons. This missense mutation replaced an absolutely conserved glycine in the H12 helix with glutamic acid, resulting in increased negative charges at the C-terminus of α-tubulin. Synaptic vesicle mistargeting in the mutant neurons was suppressed by reducing dynein function, suggesting that aberrantly high dynein activity mistargeted synaptic vesicles. We demonstrated that dynein showed preference towards binding mutant microtubules over wild-type in microtubule sedimentation assay. By contrast, neurite swelling and neurodegeneration were independent of dynein and could be ameliorated by genetic paralysis of the animal. This suggests that mutant microtubules render the neurons susceptible to recurrent mechanical stress induced by muscle activity, which is consistent with the observation that microtubule network was disorganized under electron microscopy. Our work provides insights into how microtubule-dynein interaction instructs synaptic vesicle targeting and the importance of microtubule in the maintenance of neuronal structures against constant mechanical stress. Axons and dendrites are two classes of neuronal process that differ in their functions and molecular compositions. Proteins important for synaptic functions are mostly synthesized in the cell body and sorted differentially into the axon or dendrites. Microtubules in the axon and dendrite maintain their structural integrity and regulate polarized protein transport into these compartments. We identified a novel α-tubulin mutation in C. elegans that caused mistargeting of synaptic vesicles and induced progressive neurite swelling, which resulted in late-onset neurodegeneration. We showed that this tubulin mutation weakened microtubule network and abnormally increased microtubule affinity for dynein, a motor protein responsible for cargo sorting to the dendrite. This enhanced microtubule-dynein affinity is due to augmented negative charge at the carboxyl terminus of α-tubulin. Neurite swelling and neurodegeneration could be ameliorated by reduced physical activity, suggesting that recurrent mechanical strain from muscle contraction jeopardized neurite integrity in the long run. Mutations in α- and β-tubulins are found in human neurological diseases; our findings therefore contribute to understanding the pathogenic mechanism of human neurological diseases associated with tubulin mutations.
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Affiliation(s)
- Jiun-Min Hsu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chun-Hao Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yen-Chih Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kent L. McDonald
- Electron Microscope Laboratory, University of California, Berkeley, Berkeley, California, United States of America
| | - Mark Gurling
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Albert Lee
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Gian Garriga
- Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Chun-Liang Pan
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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8
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Li J, Kurasawa Y, Wang Y, Clise-Dwyer K, Klumpp SA, Liang H, Tailor RC, Raymond AC, Estrov Z, Brandt SJ, Davis RE, Zweidler-McKay P, Amin HM, Nagarajan L. Requirement for ssbp2 in hematopoietic stem cell maintenance and stress response. THE JOURNAL OF IMMUNOLOGY 2014; 193:4654-62. [PMID: 25238756 DOI: 10.4049/jimmunol.1300337] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Transcriptional mechanisms governing hematopoietic stem cell (HSC) quiescence, self-renewal, and differentiation are not fully understood. Sequence-specific ssDNA-binding protein 2 (SSBP2) is a candidate acute myelogenous leukemia (AML) suppressor gene located at chromosome 5q14. SSBP2 binds the transcriptional adaptor protein Lim domain-binding protein 1 (LDB1) and enhances LDB1 stability to regulate gene expression. Notably, Ldb1 is essential for HSC specification during early development and maintenance in adults. We previously reported shortened lifespan and greater susceptibility to B cell lymphomas and carcinomas in Ssbp2(-/-) mice. However, whether Ssbp2 plays a regulatory role in normal HSC function and leukemogenesis is unknown. In this study, we provide several lines of evidence to demonstrate a requirement for Ssbp2 in the function and transcriptional program of hematopoietic stem and progenitor cells (HSPCs) in vivo. We found that hematopoietic tissues were hypoplastic in Ssbp2(-/-) mice, and the frequency of lymphoid-primed multipotent progenitor cells in bone marrow was reduced. Other significant features of these mice were delayed recovery from 5-fluorouracil treatment and diminished multilineage reconstitution in lethally irradiated bone marrow recipients. Dramatic reduction of Notch1 transcripts and increased expression of transcripts encoding the transcription factor E2a and its downstream target Cdkn1a also distinguished Ssbp2(-/-) HSPCs from wild-type HSPCs. Finally, a tendency toward coordinated expression of SSBP2 and the AML suppressor NOTCH1 in a subset of the Cancer Genome Atlas AML cases suggested a role for SSBP2 in AML pathogenesis. Collectively, our results uncovered a critical regulatory function for SSBP2 in HSPC gene expression and function.
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Affiliation(s)
- June Li
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Yasuhiro Kurasawa
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Yang Wang
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Karen Clise-Dwyer
- Department of Stem Cell Transplantation, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Sherry A Klumpp
- Department of Veterinary Medicine and Surgery, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Hong Liang
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Ramesh C Tailor
- Department of Radiation Physics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Aaron C Raymond
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030; Graduate Program in Genes and Development, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Zeev Estrov
- Department of Leukemia, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Stephen J Brandt
- Department of Medicine, Vanderbilt University, Nashville, TN 37232; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232; Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232; Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, TN 37232
| | - Richard E Davis
- Department of Lymphoma and Myeloma, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Patrick Zweidler-McKay
- Division of Pediatrics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
| | - Hesham M Amin
- Department of Hematopathology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030; and
| | - Lalitha Nagarajan
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030; Graduate Program in Genes and Development, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030; Department of Leukemia, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030; Graduate Program in Human Molecular Genetics, Center for Stem Cell and Developmental Biology, and Center for Cancer Genetics and Genomics, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030
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9
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Marcette JD, Chen JJ, Nonet ML. The Caenorhabditis elegans microtubule minus-end binding homolog PTRN-1 stabilizes synapses and neurites. eLife 2014; 3:e01637. [PMID: 24569480 PMCID: PMC3930908 DOI: 10.7554/elife.01637] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/17/2014] [Indexed: 12/17/2022] Open
Abstract
Microtubule dynamics facilitate neurite growth and establish morphology, but the role of minus-end binding proteins in these processes is largely unexplored. CAMSAP homologs associate with microtubule minus-ends, and are important for the stability of epithelial cell adhesions. In this study, we report morphological defects in neurons and neuromuscular defects in mutants of the C. elegans CAMSAP, ptrn-1. Mechanosensory neurons initially extend wild-type neurites, and subsequently remodel by overextending neurites and retracting synaptic branches and presynaptic varicosities. This neuronal remodeling can be activated by mutations known to alter microtubules, and depends on a functioning DLK-1 MAP kinase pathway. We found that PTRN-1 localizes to both neurites and synapses, and our results suggest that alterations of microtubule structures caused by loss of PTRN-1 function activates a remodeling program leading to changes in neurite morphology. We propose a model whereby minus-end microtubule stabilization mediated by a functional PTRN-1 is necessary for morphological maintenance of neurons. DOI: http://dx.doi.org/10.7554/eLife.01637.001.
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Affiliation(s)
- Jana Dorfman Marcette
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, United States
| | - Jessica Jie Chen
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, United States
| | - Michael L Nonet
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, United States
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10
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Bellanger JM, Cueva JG, Baran R, Tang G, Goodman MB, Debant A. The doublecortin-related gene zyg-8 is a microtubule organizer in Caenorhabditis elegans neurons. J Cell Sci 2012; 125:5417-27. [PMID: 22956537 DOI: 10.1242/jcs.108381] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Doublecortin-domain containing (DCDC) genes play key roles in the normal and pathological development of the human brain cortex. The origin of the cellular specialisation and the functional redundancy of these microtubule (MT)-associated proteins (MAPs), especially those of Doublecortin (DCX) and Doublecortin-like kinase (DCLKs) genes, is still unclear. The DCX domain has the ability to control MT architecture and bundling. However, the physiological significance of such properties is not fully understood. To address these issues, we sought post-mitotic roles for zyg-8, the sole representative of the DCX-DCLK subfamily of genes in C. elegans. Previously, zyg-8 has been shown to control anaphase-spindle positioning in one-cell stage embryos, but functions of the gene later in development have not been investigated. Here we show that wild-type zyg-8 is required beyond early embryonic divisions for proper development, spontaneous locomotion and touch sensitivity of adult worms. Consistently, we find zyg-8 expression in the six touch receptor neurons (TRNs), as well as in a subset of other neuronal and non-neuronal cells. In TRNs and motoneurons, zyg-8 controls cell body shape/polarity and process outgrowth and morphology. Ultrastructural analysis of mutant animals reveals that zyg-8 promotes structural integrity, length and number of individual MTs, as well as their bundled organisation in TRNs, with no impact on MT architecture.
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Affiliation(s)
- Jean-Michel Bellanger
- CRBM-CNRS, Université Montpellier 2, 1919, route de Mende, 34293 Montpellier, France.
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Yan D, Noma K, Jin Y. Expanding views of presynaptic terminals: new findings from Caenorhabditis elegans. Curr Opin Neurobiol 2011; 22:431-7. [PMID: 22036768 DOI: 10.1016/j.conb.2011.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 09/27/2011] [Accepted: 10/06/2011] [Indexed: 11/26/2022]
Abstract
The unique ability of chemical synapses to transmit information relies on the structural organization of presynaptic terminals. Empowered by forward genetics, research using Caenorhabditis elegans has continued to make pivotal contributions to discover conserved regulators and pathways for presynaptic development. Recent advances in microscopy have begun to pave the path for linking molecular dynamics with subsynaptic structures. Studies using diverse reporters for synapses further broaden the landscape of regulatory mechanisms underlying presynaptic differentiation. The identification of novel regulators at transcriptional and post-transcriptional levels raises new questions for understanding synapse formation at the genomic scale.
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Affiliation(s)
- Dong Yan
- Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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Burdina AO, Klosterman SM, Shtessel L, Ahmed S, Richmond JE. In vivo analysis of conserved C. elegans tomosyn domains. PLoS One 2011; 6:e26185. [PMID: 22022557 PMCID: PMC3195084 DOI: 10.1371/journal.pone.0026185] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 09/22/2011] [Indexed: 12/05/2022] Open
Abstract
Neurosecretion is critically dependent on the assembly of a macromolecular complex between the SNARE proteins syntaxin, SNAP-25 and synaptobrevin. Evidence indicates that the binding of tomosyn to syntaxin and SNAP-25 interferes with this assembly, thereby negatively regulating both synaptic transmission and peptide release. Tomosyn has two conserved domains: an N-terminal encompassing multiple WD40 repeats predicted to form two β-propeller structures and a C-terminal SNARE-binding motif. To assess the function of each domain, we performed an in vivo analysis of the N- and C- terminal domains of C. elegans tomosyn (TOM-1) in a tom-1 mutant background. We verified that both truncated TOM-1 constructs were transcribed at levels comparable to rescuing full-length TOM-1, were of the predicted size, and localized to synapses. Unlike full-length TOM-1, expression of the N- or C-terminal domains alone was unable to restore inhibitory control of synaptic transmission in tom-1 mutants. Similarly, co-expression of both domains failed to restore TOM-1 function. In addition, neither the N- nor C-terminal domain inhibited release when expressed in a wild-type background. Based on these results, we conclude that the ability of tomosyn to regulate neurotransmitter release in vivo depends on the physical integrity of the protein, indicating that both N- and C-terminal domains are necessary but not sufficient for effective inhibition of release in vivo.
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Affiliation(s)
- Anna O. Burdina
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Susan M. Klosterman
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Ludmila Shtessel
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Shawn Ahmed
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Janet E. Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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