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Haseeb MA, Bernys AC, Dickert EE, Bickel SE. An RNAi screen to identify proteins required for cohesion rejuvenation during meiotic prophase in Drosophila oocytes. G3 (BETHESDA, MD.) 2024; 14:jkae123. [PMID: 38849129 PMCID: PMC11304968 DOI: 10.1093/g3journal/jkae123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 05/23/2024] [Accepted: 05/30/2024] [Indexed: 06/09/2024]
Abstract
Accurate chromosome segregation during meiosis requires the maintenance of sister chromatid cohesion, initially established during premeiotic S phase. In human oocytes, DNA replication and cohesion establishment occur decades before chromosome segregation and deterioration of meiotic cohesion is one factor that leads to increased segregation errors as women age. Our previous work led us to propose that a cohesion rejuvenation program operates to establish new cohesive linkages during meiotic prophase in Drosophila oocytes and depends on the cohesin loader Nipped-B and the cohesion establishment factor Eco. In support of this model, we recently demonstrated that chromosome-associated cohesin turns over extensively during meiotic prophase and failure to load cohesin onto chromosomes after premeiotic S phase results in arm cohesion defects in Drosophila oocytes. To identify proteins required for prophase cohesion rejuvenation but not S phase establishment, we conducted a Gal4-UAS inducible RNAi screen that utilized two distinct germline drivers. Using this strategy, we identified 29 gene products for which hairpin expression during meiotic prophase, but not premeiotic S phase, significantly increased segregation errors. Prophase knockdown of Brahma or Pumilio, two positives with functional links to the cohesin loader, caused a significant elevation in the missegregation of recombinant homologs, a phenotype consistent with premature loss of arm cohesion. Moreover, fluorescence in situ hybridization confirmed that Brahma, Pumilio, and Nipped-B are required during meiotic prophase for the maintenance of arm cohesion. Our data support the model that Brahma and Pumilio regulate Nipped-B-dependent cohesin loading during rejuvenation. Future analyses will better define the mechanism(s) that govern meiotic cohesion rejuvenation and whether additional prophase-specific positives function in this process.
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Affiliation(s)
- Muhammad A Haseeb
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA 03755
| | - Alana C Bernys
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA 03755
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA 08544
| | - Erin E Dickert
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA 03755
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA 27710
| | - Sharon E Bickel
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA 03755
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van der Graaf K, Srivastav S, Nishad R, Stern M, McNew JA. The Drosophila Nesprin-1 homolog MSP300 is required for muscle autophagy and proteostasis. J Cell Sci 2024; 137:jcs262096. [PMID: 38757366 PMCID: PMC11213522 DOI: 10.1242/jcs.262096] [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: 03/06/2024] [Accepted: 05/13/2024] [Indexed: 05/18/2024] Open
Abstract
Nesprin proteins, which are components of the linker of nucleoskeleton and cytoskeleton (LINC) complex, are located within the nuclear envelope and play prominent roles in nuclear architecture. For example, LINC complex proteins interact with both chromatin and the cytoskeleton. Here, we report that the Drosophila Nesprin MSP300 has an additional function in autophagy within larval body wall muscles. RNAi-mediated MSP300 knockdown in larval body wall muscles resulted in defects in the contractile apparatus, muscle degeneration and defective autophagy. In particular, MSP300 knockdown caused accumulation of cytoplasmic aggregates that contained poly-ubiquitylated cargo, as well as the autophagy receptor ref(2)P (the fly homolog of p62 or SQSTM) and Atg8a. Furthermore, MSP300 knockdown larvae expressing an mCherry-GFP-tagged Atg8a transgene exhibited aberrant persistence of the GFP signal within these aggregates, indicating failure of autophagosome maturation. These autophagy deficits were similar to those exhibited by loss of the endoplasmic reticulum (ER) fusion protein Atlastin (Atl), raising the possibility that Atl and MSP300 might function in the same pathway. In support of this possibility, we found that a GFP-tagged MSP300 protein trap exhibited extensive localization to the ER. Alteration of ER-directed MSP300 might abrogate important cytoskeletal contacts necessary for autophagosome completion.
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Affiliation(s)
| | | | - Rajkishor Nishad
- Department of BioSciences, Rice University, Houston, TX 77005, USA
| | - Michael Stern
- Department of BioSciences, Rice University, Houston, TX 77005, USA
| | - James A. McNew
- Department of BioSciences, Rice University, Houston, TX 77005, USA
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Srivastav S, van der Graaf K, Jonnalagadda PC, Thawani M, McNew JA, Stern M. Motor neuron activity enhances the proteomic stress caused by autophagy defects in the target muscle. PLoS One 2024; 19:e0291477. [PMID: 38166124 PMCID: PMC10760831 DOI: 10.1371/journal.pone.0291477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 12/12/2023] [Indexed: 01/04/2024] Open
Abstract
Several lines of evidence demonstrate that increased neuronal excitability can enhance proteomic stress. For example, epilepsy can enhance the proteomic stress caused by the expression of certain aggregation-prone proteins implicated in neurodegeneration. However, unanswered questions remain concerning the mechanisms by which increased neuronal excitability accomplishes this enhancement. Here we test whether increasing neuronal excitability at a particular identified glutamatergic synapse, the Drosophila larval neuromuscular junction, can enhance the proteomic stress caused by mutations in the ER fusion/GTPase gene atlastin (atl). It was previously shown that larval muscle from the atl2 null mutant is defective in autophagy and accumulates protein aggregates containing ubiquitin (poly-UB aggregates). To determine if increased neuronal excitability might enhance the increased proteomic stress caused by atl2, we activated the TrpA1-encoded excitability channel within neurons. We found that TrpA1 activation had no effect on poly-UB aggregate accumulation in wildtype muscle, but significantly increased poly-UB aggregate number in atl2 muscle. Previous work has shown that atl loss from either neuron or muscle increases muscle poly-UB aggregate number. We found that neuronal TrpA1 activation enhanced poly-UB aggregate number when atl was removed from muscle, but not from neuron. Neuronal TrpA1 activation enhanced other phenotypes conferred by muscle atl loss, such as decreased pupal size and decreased viability. Taken together, these results indicate that the proteomic stress caused by muscle atl loss is enhanced by increasing neuronal excitability.
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Affiliation(s)
- Saurabh Srivastav
- Department of BioSciences, Rice University, Houston, TX, United States of America
| | - Kevin van der Graaf
- Department of BioSciences, Rice University, Houston, TX, United States of America
| | | | - Maanvi Thawani
- Department of BioSciences, Rice University, Houston, TX, United States of America
| | - James A. McNew
- Department of BioSciences, Rice University, Houston, TX, United States of America
| | - Michael Stern
- Department of BioSciences, Rice University, Houston, TX, United States of America
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4
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Srivastav S, van der Graaf K, Singh P, Utama AB, Meyer MD, McNew JA, Stern M. Atl (atlastin) regulates mTor signaling and autophagy in Drosophila muscle through alteration of the lysosomal network. Autophagy 2024; 20:131-150. [PMID: 37649246 PMCID: PMC10761077 DOI: 10.1080/15548627.2023.2249794] [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: 03/06/2023] [Revised: 08/08/2023] [Accepted: 08/11/2023] [Indexed: 09/01/2023] Open
Abstract
ABBREVIATIONS atl atlastin; ALR autophagic lysosome reformation; ER endoplasmic reticulum; GFP green fluorescent protein; HSP hereditary spastic paraplegia; Lamp1 lysosomal associated membrane protein 1 PolyUB polyubiquitin; RFP red fluorescent protein; spin spinster; mTor mechanistic Target of rapamycin; VCP valosin containing protein.
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Affiliation(s)
| | | | - Pratibha Singh
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, USA
| | | | - Matthew D. Meyer
- Shared Equipment Authority, Rice University, Houston, Texas, USA
| | - James A. McNew
- Department of BioSciences, Rice University, Houston, Texas, USA
| | - Michael Stern
- Department of BioSciences, Rice University, Houston, Texas, USA
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Sorkaç A, Moșneanu RA, Crown AM, Savaş D, Okoro AM, Memiş E, Talay M, Barnea G. retro-Tango enables versatile retrograde circuit tracing in Drosophila. eLife 2023; 12:e85041. [PMID: 37166114 PMCID: PMC10208638 DOI: 10.7554/elife.85041] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 05/11/2023] [Indexed: 05/12/2023] Open
Abstract
Transsynaptic tracing methods are crucial tools in studying neural circuits. Although a couple of anterograde tracing methods and a targeted retrograde tool have been developed in Drosophila melanogaster, there is still need for an unbiased, user-friendly, and flexible retrograde tracing system. Here, we describe retro-Tango, a method for transsynaptic, retrograde circuit tracing and manipulation in Drosophila. In this genetically encoded system, a ligand-receptor interaction at the synapse triggers an intracellular signaling cascade that results in reporter gene expression in presynaptic neurons. Importantly, panneuronal expression of the elements of the cascade renders this method versatile, enabling its use not only to test hypotheses but also to generate them. We validate retro-Tango in various circuits and benchmark it by comparing our findings with the electron microscopy reconstruction of the Drosophila hemibrain. Our experiments establish retro-Tango as a key method for circuit tracing in neuroscience research.
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Affiliation(s)
- Altar Sorkaç
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
| | - Rareș A Moșneanu
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
| | - Anthony M Crown
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
| | - Doruk Savaş
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
| | - Angel M Okoro
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
| | - Ezgi Memiş
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
| | - Mustafa Talay
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
| | - Gilad Barnea
- Department of Neuroscience, Brown UniversityProvidenceUnited States
- Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
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Duan Q, Estrella R, Carson A, Chen Y, Volkan PC. The effect of Drosophila attP40 background on the glomerular organization of Or47b olfactory receptor neurons. G3 (BETHESDA, MD.) 2023; 13:jkad022. [PMID: 36695023 PMCID: PMC10085800 DOI: 10.1093/g3journal/jkad022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 01/26/2023]
Abstract
Bacteriophage integrase-directed insertion of transgenic constructs into specific genomic loci has been widely used by Drosophila community. The attP40 landing site located on the second chromosome gained popularity because of its high inducible transgene expression levels. Here, unexpectedly, we found that homozygous attP40 chromosome disrupts normal glomerular organization of Or47b olfactory receptor neuron (ORN) class in Drosophila. This effect is not likely to be caused by the loss of function of Msp300, where the attP40 docking site is inserted. Moreover, the attP40 background seems to genetically interact with the second chromosome Or47b-GAL4 driver, which results in a similar glomerular defect. Whether the ORN phenotype is caused by the neighbouring genes around Msp300 locus in the presence of attP40-based insertions or a second unknown mutation in the attP40 background remains elusive. Our findings tell a cautionary tale about using this popular transgenic landing site, highlighting the importance of rigorous controls to rule out the attP40 landing site-associated background effects.
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Affiliation(s)
- Qichen Duan
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Rachel Estrella
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Allison Carson
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Yang Chen
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Pelin C Volkan
- Department of Biology, Duke University, Durham, NC 27708, USA
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