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Chitre K, Kairamkonda S, Dwivedi MK, Yadav S, Kumar V, Sikdar SK, Nongthomba U. Beadex, the Drosophila LIM only protein, is required for the growth of the larval neuromuscular junction. J Neurophysiol 2024; 132:418-432. [PMID: 38838299 DOI: 10.1152/jn.00064.2024] [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: 02/12/2024] [Revised: 05/31/2024] [Accepted: 06/05/2024] [Indexed: 06/07/2024] Open
Abstract
The appropriate growth of the neurons, accurate organization of their synapses, and successful neurotransmission are indispensable for sensorimotor activities. These processes are highly dynamic and tightly regulated. Extensive genetic, molecular, physiological, and behavioral studies have identified many molecular candidates and investigated their roles in various neuromuscular processes. In this article, we show that Beadex (Bx), the Drosophila LIM only (LMO) protein, is required for motor activities and neuromuscular growth of Drosophila. The larvae bearing Bx7, a null allele of Bx, and the RNAi-mediated neuronal-specific knockdown of Bx show drastically reduced crawling behavior, a diminished synaptic span of the neuromuscular junctions (NMJs) and an increased spontaneous neuronal firing with altered motor patterns in the central pattern generators (CPGs). Microarray studies identified multiple targets of Beadex that are involved in different cellular and molecular pathways, including those associated with the cytoskeleton and mitochondria that could be responsible for the observed neuromuscular defects. With genetic interaction studies, we further show that Highwire (Hiw), a negative regulator of synaptic growth at the NMJs, negatively regulates Bx, as the latter's deficiency was able to rescue the phenotype of the Hiw null mutant, HiwDN. Thus, our data indicate that Beadex functions downstream of Hiw to regulate the larval synaptic growth and physiology.NEW & NOTEWORTHY A novel role for Beadex (Bx) regulates the larval neuromuscular junction (NMJ) structure and function in a tissue-specific manner. Bx is expressed in a subset of Toll-6-expressing neurons and is involved in regulating synaptic span and physiology, possibly through its negative interaction with Highwire (Hiw). The findings of this study provide insights into the molecular mechanisms underlying NMJ development and function and warrant further investigation to understand the role of Bx in these processes fully.
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Affiliation(s)
- Kripa Chitre
- Department of Development Biology and Genetics (DBG), Indian Institute of Science (IISc), Bangalore, India
| | - Subhash Kairamkonda
- Department of Development Biology and Genetics (DBG), Indian Institute of Science (IISc), Bangalore, India
| | - Manish Kumar Dwivedi
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Saumitra Yadav
- Molecular Biophysics Unit (MBU), Indian Institute of Science (IISc), Bangalore, India
| | - Vimlesh Kumar
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Sujit K Sikdar
- Molecular Biophysics Unit (MBU), Indian Institute of Science (IISc), Bangalore, India
| | - Upendra Nongthomba
- Department of Development Biology and Genetics (DBG), Indian Institute of Science (IISc), Bangalore, India
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Palumbo RJ, Yang Y, Feigon J, Hanes SD. Catalytic activity of the Bin3/MePCE methyltransferase domain is dispensable for 7SK snRNP function in Drosophila melanogaster. Genetics 2024; 226:iyad203. [PMID: 37982586 PMCID: PMC10763541 DOI: 10.1093/genetics/iyad203] [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: 05/31/2023] [Revised: 10/27/2023] [Accepted: 11/13/2023] [Indexed: 11/21/2023] Open
Abstract
Methylphosphate Capping Enzyme (MePCE) monomethylates the gamma phosphate at the 5' end of the 7SK noncoding RNA, a modification thought to protect 7SK from degradation. 7SK serves as a scaffold for assembly of a snRNP complex that inhibits transcription by sequestering the positive elongation factor P-TEFb. While much is known about the biochemical activity of MePCE in vitro, little is known about its functions in vivo, or what roles-if any-there are for regions outside the conserved methyltransferase domain. Here, we investigated the role of Bin3, the Drosophila ortholog of MePCE, and its conserved functional domains in Drosophila development. We found that bin3 mutant females had strongly reduced rates of egg-laying, which was rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 promotes fecundity by repressing P-TEFb. bin3 mutants also exhibited neuromuscular defects, analogous to a patient with MePCE haploinsufficiency. These defects were also rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 and MePCE have conserved roles in promoting neuromuscular function by repressing P-TEFb. Unexpectedly, we found that a Bin3 catalytic mutant (Bin3Y795A) could still bind and stabilize 7SK and rescue all bin3 mutant phenotypes, indicating that Bin3 catalytic activity is dispensable for 7SK stability and snRNP function in vivo. Finally, we identified a metazoan-specific motif (MSM) outside of the methyltransferase domain and generated mutant flies lacking this motif (Bin3ΔMSM). Bin3ΔMSM mutant flies exhibited some-but not all-bin3 mutant phenotypes, suggesting that the MSM is required for a 7SK-independent, tissue-specific function of Bin3.
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Affiliation(s)
- Ryan J Palumbo
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Yuan Yang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Steven D Hanes
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
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Palumbo RJ, Hanes SD. Catalytic activity of the Bin3/MEPCE methyltransferase domain is dispensable for 7SK snRNP function in Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543302. [PMID: 37333392 PMCID: PMC10274667 DOI: 10.1101/2023.06.01.543302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Methylphosphate Capping Enzyme (MEPCE) monomethylates the gamma phosphate at the 5' end of the 7SK noncoding RNA, a modification thought to protect 7SK from degradation. 7SK serves as a scaffold for assembly of a snRNP complex that inhibits transcription by sequestering the positive elongation factor P-TEFb. While much is known about the biochemical activity of MEPCE in vitro, little is known about its functions in vivo, or what roles- if any-there are for regions outside the conserved methyltransferase domain. Here, we investigated the role of Bin3, the Drosophila ortholog of MEPCE, and its conserved functional domains in Drosophila development. We found that bin3 mutant females had strongly reduced rates of egg-laying, which was rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 promotes fecundity by repressing P-TEFb. bin3 mutants also exhibited neuromuscular defects, analogous to a patient with MEPCE haploinsufficiency. These defects were also rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 and MEPCE have conserved roles in promoting neuromuscular function by repressing P-TEFb. Unexpectedly, we found that a Bin3 catalytic mutant (Bin3Y795A) could still bind and stabilize 7SK and rescue all bin3 mutant phenotypes, indicating that Bin3 catalytic activity is dispensable for 7SK stability and snRNP function in vivo. Finally, we identified a metazoan-specific motif (MSM) outside of the methyltransferase domain and generated mutant flies lacking this motif (Bin3ΔMSM). Bin3ΔMSM mutant flies exhibited some-but not all-bin3 mutant phenotypes, suggesting that the MSM is required for a 7SK-independent, tissue-specific function of Bin3.
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Affiliation(s)
- Ryan J Palumbo
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University 750 East Adams Street, 4283 Weiskotten Hall, Syracuse, New York, 13210
| | - Steven D Hanes
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University 750 East Adams Street, 4283 Weiskotten Hall, Syracuse, New York, 13210
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Chatterjee A, Aavula K, Nongthomba U. Beadex, a homologue of the vertebrate LIM domain only protein, is a novel regulator of crystal cell development in Drosophila melanogaster. J Genet 2019; 98:107. [PMID: 31819023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Haematopoiesis is a complex process in which the regulatory mechanisms of several implicated transcription factors remain uncertain. Drosophila melanogaster is an excellent model to resolve the unanswered questions about the blood cell development. This study describes the role of Beadex, a Drosophila homologue of LIM domain only 2 (LMO2), in haematopoiesis. Mutants of Beadex were analysed for blood cell abnormalities. Crystal cells, a subset of haemocytes, were significantly more in Beadex hypermorphic flies. Similarly, Beadex misexpression in prohemocytes altered the crystal cell numbers. Stage-specific misexpression analyses demonstrated that Beadex functions after the prohemocytes enter the crystal cell lineage. We also discovered that Pannier-U-shaped complex is a negative regulator of the crystal cell differentiation and is possibly negatively regulated by Beadex through its interaction with Pannier. We, therefore, suggest the mechanism of two novel regulators of crystal cell specification-Beadex and Pannier-during Drosophila haematopoiesis.
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Affiliation(s)
- Arunita Chatterjee
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru 560 012, India.
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Hoedjes KM, van den Heuvel J, Kapun M, Keller L, Flatt T, Zwaan BJ. Distinct genomic signals of lifespan and life history evolution in response to postponed reproduction and larval diet in Drosophila. Evol Lett 2019; 3:598-609. [PMID: 31867121 PMCID: PMC6906992 DOI: 10.1002/evl3.143] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 09/08/2019] [Accepted: 09/11/2019] [Indexed: 12/14/2022] Open
Abstract
Reproduction and diet are two major factors controlling the physiology of aging and life history, but how they interact to affect the evolution of longevity is unknown. Moreover, although studies of large-effect mutants suggest an important role of nutrient sensing pathways in regulating aging, the genetic basis of evolutionary changes in lifespan remains poorly understood. To address these questions, we analyzed the genomes of experimentally evolved Drosophila melanogaster populations subjected to a factorial combination of two selection regimes: reproductive age (early versus postponed), and diet during the larval stage ("low," "control," "high"), resulting in six treatment combinations with four replicate populations each. Selection on reproductive age consistently affected lifespan, with flies from the postponed reproduction regime having evolved a longer lifespan. In contrast, larval diet affected lifespan only in early-reproducing populations: flies adapted to the "low" diet lived longer than those adapted to control diet. Here, we find genomic evidence for strong independent evolutionary responses to either selection regime, as well as loci that diverged in response to both regimes, thus representing genomic interactions between the two. Overall, we find that the genomic basis of longevity is largely independent of dietary adaptation. Differentiated loci were not enriched for "canonical" longevity genes, suggesting that naturally occurring genic targets of selection for longevity differ qualitatively from variants found in mutant screens. Comparing our candidate loci to those from other "evolve and resequence" studies of longevity demonstrated significant overlap among independent experiments. This suggests that the evolution of longevity, despite its presumed complex and polygenic nature, might be to some extent convergent and predictable.
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Affiliation(s)
- Katja M. Hoedjes
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
| | - Joost van den Heuvel
- Laboratory of Genetics, Plant Sciences GroupWageningen UniversityWageningenThe Netherlands
- Institute for Cell and Molecular BiosciencesNewcastle UniversityNewcastle Upon TyneUnited Kingdom
| | - Martin Kapun
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
- Department of BiologyUniversity of FribourgFribourgSwitzerland
- Current Address: Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Laurent Keller
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
| | - Thomas Flatt
- Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
- Department of BiologyUniversity of FribourgFribourgSwitzerland
| | - Bas J. Zwaan
- Laboratory of Genetics, Plant Sciences GroupWageningen UniversityWageningenThe Netherlands
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CHATTERJEE ARUNITA, AAVULA KUMAR, NONGTHOMBA UPENDRA. Beadex, a homologue of the vertebrate LIM domain only protein, is a novel regulator of crystal cell development in Drosophila melanogaster. J Genet 2019. [DOI: 10.1007/s12041-019-1154-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Guo P, Xu X, Wang F, Yuan X, Tu Y, Zhang B, Zheng H, Yu D, Ge W, Gong Z, Yang X, Xi Y. A Novel Neuroprotective Role of Phosphatase of Regenerating Liver-1 against CO 2 Stimulation in Drosophila. iScience 2019; 19:291-302. [PMID: 31404830 PMCID: PMC6700421 DOI: 10.1016/j.isci.2019.07.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/10/2019] [Accepted: 07/16/2019] [Indexed: 12/27/2022] Open
Abstract
Neuroprotection is essential for the maintenance of normal physiological functions in the nervous system. This is especially true under stress conditions. Here, we demonstrate a novel protective function of PRL-1 against CO2 stimulation in Drosophila. In the absence of PRL-1, flies exhibit a permanent held-up wing phenotype upon CO2 exposure. Knockdown of the CO2 olfactory receptor, Gr21a, suppresses the phenotype. Our genetic data indicate that the wing phenotype is due to a neural dysfunction. PRL-1 physically interacts with Uex and controls Uex expression levels. Knockdown of Uex alone leads to a similar wing held-up phenotype to that of PRL-1 mutants. Uex acts downstream of PRL-1. Elevated Uex levels in PRL-1 mutants prevent the CO2-induced phenotype. PRL-1 and Uex are required for a wide range of neurons to maintain neuroprotective functions. Expression of human homologs of PRL-1 could rescue the phenotype in Drosophila, suggesting a similar function in humans. PRL-1 functions to protect the nervous system against olfactory CO2 stimulation PRL-1 physically interacts with Uex and controls Uex expression levels PRLs may retain a similar neuroprotective function in humans
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Affiliation(s)
- Pengfei Guo
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China; College of Life Sciences, Zhejiang University, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Xiao Xu
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China; College of Life Sciences, Zhejiang University, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Fang Wang
- College of Life Sciences, Zhejiang University, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Xin Yuan
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Yinqi Tu
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China; College of Life Sciences, Zhejiang University, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Bei Zhang
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China; College of Life Sciences, Zhejiang University, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Huimei Zheng
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Danqing Yu
- The Second Affiliated Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Wanzhong Ge
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Zhefeng Gong
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China
| | - Xiaohang Yang
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China; Joint Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Zhejiang University, Hangzhou, Zhejiang Province 310058, China.
| | - Yongmei Xi
- Institute of Genetics and Department of Genetics, Division of Human Reproduction and Developmental Genetics of the Women's Hospital, Zhejiang University School of Medicine, Yuhangtang Road 866, Xihu District, Hangzhou, Zhejiang Province 310058, China.
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Kairamkonda S, Nongthomba U. Beadex, a Drosophila LIM domain only protein, function in follicle cells is essential for egg development and fertility. Exp Cell Res 2018; 367:97-103. [PMID: 29580687 DOI: 10.1016/j.yexcr.2018.03.029] [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: 02/07/2017] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 11/25/2022]
Abstract
LIM domain, constituted by two tandem C2H2 zinc finger motif, proteins regulate several biological processes. They are usually found associated with various functional domains like Homeodomain, kinase domain and other protein binding domains. LIM proteins that are devoid of other domains are called LIM only proteins (LMO). LMO proteins were first identified in humans and are implicated in development and oncogenesis. They regulate various cell specifications by regulating the activity of respective transcriptional complexes. The Drosophila LMO protein (dLMO), Beadex (Bx), regulates various developmental processes like wing margin development and bristle development. It also regulates Drosophila behavior in response to cocaine and ethanol. We have previously generated Bx null flies and shown its essential function in neurons for multiple aspects of female reproduction. However, it was not known whether Bx affects reproduction through its independent function in ovaries. In this paper we show that female flies null for Bx lay eggs with multiple defects. Further, through knock down studies we demonstrate that function of Bx in follicle cells is required for normal egg development. We also show that function of Bx is particularly required in border cells for Drosophila fertility.
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Affiliation(s)
- Subhash Kairamkonda
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India
| | - Upendra Nongthomba
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India.
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Stress-induced reproductive arrest in Drosophila occurs through ETH deficiency-mediated suppression of oogenesis and ovulation. BMC Biol 2018; 16:18. [PMID: 29382341 PMCID: PMC5791332 DOI: 10.1186/s12915-018-0484-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 01/08/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Environmental stressors induce changes in endocrine state, leading to energy re-allocation from reproduction to survival. Female Drosophila melanogaster respond to thermal and nutrient stressors by arresting egg production through elevation of the steroid hormone ecdysone. However, the mechanisms through which this reproductive arrest occurs are not well understood. RESULTS Here we report that stress-induced elevation of ecdysone is accompanied by decreased levels of ecdysis triggering hormone (ETH). Depressed levels of circulating ETH lead to attenuated activity of its targets, including juvenile hormone-producing corpus allatum and, as we describe here for the first time, octopaminergic neurons of the oviduct. Elevation of steroid thereby results in arrested oogenesis, reduced octopaminergic input to the reproductive tract, and consequent suppression of ovulation. ETH mitigates heat or nutritional stress-induced attenuation of fecundity, which suggests that its deficiency is critical to reproductive adaptability. CONCLUSIONS Our findings indicate that, as a dual regulator of octopamine and juvenile hormone release, ETH provides a link between stress-induced elevation of ecdysone levels and consequent reduction in fecundity.
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