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Anil AT, Pandian R, Mishra SK. Introns with branchpoint-distant 3' splice sites: Splicing mechanism and regulatory roles. Biophys Chem 2024; 314:107307. [PMID: 39173313 DOI: 10.1016/j.bpc.2024.107307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 07/26/2024] [Accepted: 08/07/2024] [Indexed: 08/24/2024]
Abstract
The two transesterification reactions of pre-mRNA splicing require highly complex yet well-controlled rearrangements of small nuclear RNAs and proteins (snRNP) in the spliceosome. The efficiency and accuracy of these reactions are critical for gene expression, as almost all human genes pass through pre-mRNA splicing. Key parameters that determine the splicing outcome are the length of the intron, the strengths of its splicing signals and gaps between them, and the presence of splicing controlling elements. In particular, the gap between the branchpoint (BP) and the 3' splice site (ss) of introns is a major determinant of the splicing efficiency. This distance falls within a small range across the introns of an organism. The constraints exist possibly because BP and 3'ss are recognized by BP-binding proteins, U2 snRNP and U2 accessory factors (U2AF) in a coordinated manner. Furthermore, varying distances between the two signals may also affect the second transesterification reaction since the intervening RNA needs to be accurately positioned within the complex RNP machinery. Splicing such pre-mRNAs requires cis-acting elements in the RNA and many trans-acting splicing regulators. Regulated pre-mRNA splicing with BP-distant 3'ss adds another layer of control to gene expression and promotes alternative splicing.
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Affiliation(s)
- Anupa T Anil
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306, Punjab, India
| | - Rakesh Pandian
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306, Punjab, India
| | - Shravan Kumar Mishra
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306, Punjab, India.
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Balachandra S, Amodeo AA. Bellymount-Pulsed Tracking: A Novel Approach for Real-Time In vivo Imaging of Drosophila Abdominal Tissues. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.31.587498. [PMID: 38617254 PMCID: PMC11014545 DOI: 10.1101/2024.03.31.587498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Quantitative live imaging is a valuable tool that offers insights into cellular dynamics. However, many fundamental biological processes are incompatible with current live imaging modalities. Drosophila oogenesis is a well-studied system that has provided molecular insights into a range of cellular and developmental processes. The length of the oogenesis coupled with the requirement for inputs from multiple tissues has made long-term culture challenging. Here, we have developed Bellymount-Pulsed Tracking (Bellymount-PT), which allows continuous, non-invasive live imaging of Drosophila oogenesis inside the female abdomen for up to 16 hours. Bellymount-PT improves upon the existing Bellymount technique by adding pulsed anesthesia with periods of feeding that support the long-term survival of flies during imaging. Using Bellymount-PT we measure key events of oogenesis including egg chamber growth, yolk uptake, and transfer of specific proteins to the oocyte during nurse cell dumping with high spatiotemporal precision within the abdomen of a live female.
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Affiliation(s)
- Shruthi Balachandra
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Amanda A Amodeo
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
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Vincow ES, Thomas RE, Milstein G, Pareek G, Bammler T, MacDonald J, Pallanck L. Glucocerebrosidase deficiency leads to neuropathology via cellular immune activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571406. [PMID: 38168223 PMCID: PMC10760128 DOI: 10.1101/2023.12.13.571406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Mutations in GBA (glucosylceramidase beta), which encodes the lysosomal enzyme glucocerebrosidase (GCase), are the strongest genetic risk factor for the neurodegenerative disorders Parkinson's disease (PD) and Lewy body dementia. Recent work has suggested that neuroinflammation may be an important factor in the risk conferred by GBA mutations. We therefore systematically tested the contributions of immune-related genes to neuropathology in a Drosophila model of GCase deficiency. We identified target immune factors via RNA-Seq and proteomics on heads from GCase-deficient flies, which revealed both increased abundance of humoral factors and increased macrophage activation. We then manipulated the identified immune factors and measured their effect on head protein aggregates, a hallmark of neurodegenerative disease. Genetic ablation of humoral (secreted) immune factors did not suppress the development of protein aggregation. By contrast, re-expressing Gba1b in activated macrophages suppressed head protein aggregation in Gba1b mutants and rescued their lifespan and behavioral deficits. Moreover, reducing the GCase substrate glucosylceramide in activated macrophages also ameliorated Gba1b mutant phenotypes. Taken together, our findings show that glucosylceramide accumulation due to GCase deficiency leads to macrophage activation, which in turn promotes the development of neuropathology.
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Affiliation(s)
- Evelyn S. Vincow
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Ruth E. Thomas
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Gillian Milstein
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Gautam Pareek
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Theo Bammler
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America
| | - James MacDonald
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, United States of America
| | - Leo Pallanck
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
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Gabbert AM, Campanale JP, Mondo JA, Mitchell NP, Myers A, Streichan SJ, Miolane N, Montell DJ. Septins regulate border cell surface geometry, shape, and motility downstream of Rho in Drosophila. Dev Cell 2023; 58:1399-1413.e5. [PMID: 37329886 PMCID: PMC10519140 DOI: 10.1016/j.devcel.2023.05.017] [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: 09/18/2022] [Revised: 04/14/2023] [Accepted: 05/25/2023] [Indexed: 06/19/2023]
Abstract
Septins self-assemble into polymers that bind and deform membranes in vitro and regulate diverse cell behaviors in vivo. How their in vitro properties relate to their in vivo functions is under active investigation. Here, we uncover requirements for septins in detachment and motility of border cell clusters in the Drosophila ovary. Septins and myosin colocalize dynamically at the cluster periphery and share phenotypes but, surprisingly, do not impact each other. Instead, Rho independently regulates myosin activity and septin localization. Active Rho recruits septins to membranes, whereas inactive Rho sequesters septins in the cytoplasm. Mathematical analyses identify how manipulating septin expression levels alters cluster surface texture and shape. This study shows that the level of septin expression differentially regulates surface properties at different scales. This work suggests that downstream of Rho, septins tune surface deformability while myosin controls contractility, the combination of which governs cluster shape and movement.
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Affiliation(s)
- Allison M Gabbert
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Joseph P Campanale
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - James A Mondo
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Noah P Mitchell
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Physics Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Adele Myers
- Electrical and Computer Engineering Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Sebastian J Streichan
- Physics Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Nina Miolane
- Electrical and Computer Engineering Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Denise J Montell
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
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