1
|
Tan QH, Otgonbaatar A, Kaur P, Ga AF, Harmston NP, Tolwinski NS. The Wnt Co-Receptor PTK7/Otk and Its Homolog Otk-2 in Neurogenesis and Patterning. Cells 2024; 13:365. [PMID: 38474329 PMCID: PMC10930971 DOI: 10.3390/cells13050365] [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: 11/20/2023] [Revised: 02/09/2024] [Accepted: 02/16/2024] [Indexed: 03/14/2024] Open
Abstract
Wnt signaling is a highly conserved metazoan pathway that plays a crucial role in cell fate determination and morphogenesis during development. Wnt ligands can induce disparate cellular responses. The exact mechanism behind these different outcomes is not fully understood but may be due to interactions with different receptors on the cell membrane. PTK7/Otk is a transmembrane receptor that is implicated in various developmental and physiological processes including cell polarity, cell migration, and invasion. Here, we examine two roles of Otk-1 and Otk-2 in patterning and neurogenesis. We find that Otk-1 is a positive regulator of signaling and Otk-2 functions as its inhibitor. We propose that PTK7/Otk functions in signaling, cell migration, and polarity contributing to the diversity of cellular responses seen in Wnt-mediated processes.
Collapse
Affiliation(s)
- Qian Hui Tan
- Division of Science, Yale-NUS College, Singapore 138527, Singapore (A.O.); (P.K.); (A.F.G.); (N.P.H.)
| | - Agimaa Otgonbaatar
- Division of Science, Yale-NUS College, Singapore 138527, Singapore (A.O.); (P.K.); (A.F.G.); (N.P.H.)
| | - Prameet Kaur
- Division of Science, Yale-NUS College, Singapore 138527, Singapore (A.O.); (P.K.); (A.F.G.); (N.P.H.)
| | - Angelica Faye Ga
- Division of Science, Yale-NUS College, Singapore 138527, Singapore (A.O.); (P.K.); (A.F.G.); (N.P.H.)
| | - Nathan P. Harmston
- Division of Science, Yale-NUS College, Singapore 138527, Singapore (A.O.); (P.K.); (A.F.G.); (N.P.H.)
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore 169857, Singapore
- Molecular Biosciences Division, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - Nicholas S. Tolwinski
- Division of Science, Yale-NUS College, Singapore 138527, Singapore (A.O.); (P.K.); (A.F.G.); (N.P.H.)
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore 169857, Singapore
| |
Collapse
|
2
|
Ghosh S, Chakraborti S, Devi D, Sahu R, Mandal S, Mandal L. A conserved nutrient responsive axis mediates autophagic degradation of miRNA-mRNA hybrids in blood cell progenitors. Nucleic Acids Res 2024; 52:385-403. [PMID: 37994707 PMCID: PMC10783512 DOI: 10.1093/nar/gkad1047] [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: 01/30/2023] [Revised: 09/05/2023] [Accepted: 10/24/2023] [Indexed: 11/24/2023] Open
Abstract
In animals, microRNAs are amongst the primary non-coding RNAs involved in regulating the gene expression of a cell. Most mRNAs in a cell are targeted by one or many miRNAs. Although several mechanisms can be attributed to the degradation of miRNA and mRNA within a cell, but the involvement of autophagy in the clearance of miRNA and its target mRNA is not known. We discover a leucine-responsive axis in blood cell progenitors that can mediate an autophagy-directed degradation of miRNA-bound mRNA in Drosophila melanogaster and Homo sapiens. This previously unknown miRNA clearance axis is activated upon amino acid deprivation that can traffic miRNA-mRNA-loaded Argonaute for autophagic degradation in a p62-dependent manner. Thus, our research not only reports a novel axis that can address the turnover of a catalytically active miRISC but also elucidates a slicer-independent mechanism through which autophagy can selectively initiate the clearance of target mRNA.
Collapse
Affiliation(s)
- Sushmit Ghosh
- Developmental Genetic Laboratory, 140306 Punjab, India
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), SAS Nagar, Knowledge City, Sector 81, Manauli P.O., 140306 Punjab, India
| | - Sreemoyee Chakraborti
- Developmental Genetic Laboratory, 140306 Punjab, India
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), SAS Nagar, Knowledge City, Sector 81, Manauli P.O., 140306 Punjab, India
| | - Devki Devi
- Developmental Genetic Laboratory, 140306 Punjab, India
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), SAS Nagar, Knowledge City, Sector 81, Manauli P.O., 140306 Punjab, India
| | - Rajesh Sahu
- Developmental Genetic Laboratory, 140306 Punjab, India
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), SAS Nagar, Knowledge City, Sector 81, Manauli P.O., 140306 Punjab, India
| | - Sudip Mandal
- Molecular, Cell and Developmental Biology Laboratory,140306 Punjab, India
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), SAS Nagar, Knowledge City, Sector 81, Manauli P.O., 140306 Punjab, India
| | - Lolitika Mandal
- Developmental Genetic Laboratory, 140306 Punjab, India
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), SAS Nagar, Knowledge City, Sector 81, Manauli P.O., 140306 Punjab, India
| |
Collapse
|
3
|
Richardson K, Sengupta M, Sujkowski A, Libohova K, Harris AC, Wessells R, Merry DE, Todi SV. A phenotypically robust model of spinal and bulbar muscular atrophy in Drosophila. J Neurosci Res 2024; 102:e25278. [PMID: 38284836 DOI: 10.1002/jnr.25278] [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: 07/19/2023] [Revised: 10/14/2023] [Accepted: 11/05/2023] [Indexed: 01/30/2024]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is an X-linked disorder that affects males who inherit the androgen receptor (AR) gene with an abnormal CAG triplet repeat expansion. The resulting protein contains an elongated polyglutamine (polyQ) tract and causes motor neuron degeneration in an androgen-dependent manner. The precise molecular sequelae of SBMA are unclear. To assist with its investigation and the identification of therapeutic options, we report here a new model of SBMA in Drosophila melanogaster. We generated transgenic flies that express the full-length, human AR with a wild-type or pathogenic polyQ repeat. Each transgene is inserted into the same safe harbor site on the third chromosome of the fly as a single copy and in the same orientation. Expression of pathogenic AR, but not of its wild-type variant, in neurons or muscles leads to consistent, progressive defects in longevity and motility that are concomitant with polyQ-expanded AR protein aggregation and reduced complexity in neuromuscular junctions. Additional assays show adult fly eye abnormalities associated with the pathogenic AR species. The detrimental effects of pathogenic AR are accentuated by feeding flies the androgen, dihydrotestosterone. This new, robust SBMA model can be a valuable tool toward future investigations of this incurable disease.
Collapse
Affiliation(s)
- Kristin Richardson
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Medha Sengupta
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania, USA
| | - Alyson Sujkowski
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Autumn C Harris
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
- Maximizing Access to Science Careers Program, Wayne State University, Detroit, Michigan, USA
| | - Robert Wessells
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Diane E Merry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
- Maximizing Access to Science Careers Program, Wayne State University, Detroit, Michigan, USA
- Department of Neurology, Wayne State University School of Medicine, Detroit, Michigan, USA
| |
Collapse
|
4
|
Hilgers V. Regulation of neuronal RNA signatures by ELAV/Hu proteins. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1733. [PMID: 35429136 DOI: 10.1002/wrna.1733] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/18/2022] [Accepted: 03/23/2022] [Indexed: 12/30/2022]
Abstract
The RNA-binding proteins encoded by the highly conserved elav/Hu gene family, found in all metazoans, regulate the expression of a wide range of genes, at both the co-transcriptional and posttranscriptional level. Nervous-system-specific ELAV/Hu proteins are prominent for their essential role in neuron differentiation, and mutations have been associated with human neurodevelopmental and neurodegenerative diseases. Drosophila ELAV, the founding member of the protein family, mediates the synthesis of neuronal RNA signatures by promoting alternative splicing and alternative polyadenylation of hundreds of genes. The recent identification of ELAV's direct RNA targets revealed the protein's central role in shaping the neuronal transcriptome, and highlighted the importance of neuronal transcript signatures for neuron maintenance and organism survival. Animals have evolved multiple cellular mechanisms to ensure robustness of ELAV/Hu function. In Drosophila, elav autoregulates in a 3'UTR-dependent manner to maintain optimal protein levels. A complete absence of ELAV causes the activation and nuclear localization of the normally cytoplasmic paralogue FNE, in a process termed EXon-Activated functional Rescue (EXAR). Other species, including mammals, seem to utilize different strategies, such as protein redundancy, to maintain ELAV protein function and effectively safeguard the identity of the neuronal transcriptome. This article is categorized under: RNA Processing > 3' End Processing RNA in Disease and Development > RNA in Development RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
Collapse
Affiliation(s)
- Valérie Hilgers
- Max-Planck-Institute of Immunobiology and Epigenetics, Freiburg, Germany
| |
Collapse
|
5
|
Carrasco J, Mateos F, Hilgers V. A critical developmental window for ELAV/Hu-dependent mRNA signatures at the onset of neuronal differentiation. Cell Rep 2022; 41:111542. [PMID: 36288718 PMCID: PMC9631114 DOI: 10.1016/j.celrep.2022.111542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/16/2022] [Accepted: 09/30/2022] [Indexed: 12/01/2022] Open
Abstract
Cell-type-specific gene regulatory programs are essential for cell differentiation and function. In animal neurons, the highly conserved ELAV/Hu family of proteins promotes alternative splicing and polyadenylation of mRNA precursors to create unique neuronal transcript isoforms. Here, we assess transcriptome profiles and neurogenesis success in Drosophila models engineered to express differing levels of ELAV activity in the course of development. We show that the ELAV-mediated establishment of a subset of neuronal mRNA isoforms at the onset of neuron differentiation constitutes a developmental bottleneck that cannot be overcome later by the nuclear activation of the paralog found in neurons (FNE). Loss of ELAV function outside of that critical time window results in neurological defects. We find that FNE, when activated early enough, can restore ELAV-dependent neuronal mRNA isoforms and fully rescue development. Our findings demonstrate the essential role of robust cellular strategies to maintain ELAV activity and intact neuronal signatures in neurogenesis and neuronal function.
Collapse
Affiliation(s)
- Judit Carrasco
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Faculty of Biology, Albert Ludwig University, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology (IMPRS-MCB), 79108 Freiburg, Germany
| | - Fernando Mateos
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Valérie Hilgers
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany.
| |
Collapse
|
6
|
Johnson SL, Prifti MV, Sujkowski A, Libohova K, Blount JR, Hong L, Tsou WL, Todi SV. Drosophila as a Model of Unconventional Translation in Spinocerebellar Ataxia Type 3. Cells 2022; 11:cells11071223. [PMID: 35406787 PMCID: PMC8997593 DOI: 10.3390/cells11071223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 03/29/2022] [Accepted: 03/31/2022] [Indexed: 12/21/2022] Open
Abstract
RNA toxicity contributes to diseases caused by anomalous nucleotide repeat expansions. Recent work demonstrated RNA-based toxicity from repeat-associated, non-AUG-initiated translation (RAN translation). RAN translation occurs around long nucleotide repeats that form hairpin loops, allowing for translation initiation in the absence of a start codon that results in potentially toxic, poly-amino acid repeat-containing proteins. Discovered in Spinocerebellar Ataxia Type (SCA) 8, RAN translation has been documented in several repeat-expansion diseases, including in the CAG repeat-dependent polyglutamine (polyQ) disorders. The ATXN3 gene, which causes SCA3, also known as Machado–Joseph Disease (MJD), contains a CAG repeat that is expanded in disease. ATXN3 mRNA possesses features linked to RAN translation. In this paper, we examined the potential contribution of RAN translation to SCA3/MJD in Drosophila by using isogenic lines that contain homomeric or interrupted CAG repeats. We did not observe unconventional translation in fly neurons or glia. However, our investigations indicate differential toxicity from ATXN3 protein-encoding mRNA that contains pure versus interrupted CAG repeats. Additional work suggests that this difference may be due in part to toxicity from homomeric CAG mRNA. We conclude that Drosophila is not suitable to model RAN translation for SCA3/MJD, but offers clues into the potential pathogenesis stemming from CAG repeat-containing mRNA in this disorder.
Collapse
Affiliation(s)
- Sean L. Johnson
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Matthew V. Prifti
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Alyson Sujkowski
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Jessica R. Blount
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Luke Hong
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Sokol V. Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Correspondence:
| |
Collapse
|
7
|
Wei L, Lai EC. Regulation of the Alternative Neural Transcriptome by ELAV/Hu RNA Binding Proteins. Front Genet 2022; 13:848626. [PMID: 35281806 PMCID: PMC8904962 DOI: 10.3389/fgene.2022.848626] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 02/01/2022] [Indexed: 11/30/2022] Open
Abstract
The process of alternative polyadenylation (APA) generates multiple 3' UTR isoforms for a given locus, which can alter regulatory capacity and on occasion change coding potential. APA was initially characterized for a few genes, but in the past decade, has been found to be the rule for metazoan genes. While numerous differences in APA profiles have been catalogued across genetic conditions, perturbations, and diseases, our knowledge of APA mechanisms and biology is far from complete. In this review, we highlight recent findings regarding the role of the conserved ELAV/Hu family of RNA binding proteins (RBPs) in generating the broad landscape of lengthened 3' UTRs that is characteristic of neurons. We relate this to their established roles in alternative splicing, and summarize ongoing directions that will further elucidate the molecular strategies for neural APA, the in vivo functions of ELAV/Hu RBPs, and the phenotypic consequences of these regulatory paradigms in neurons.
Collapse
Affiliation(s)
- Lu Wei
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Eric C. Lai
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, United States
| |
Collapse
|
8
|
Hildebrandt K, Kolb D, Klöppel C, Kaspar P, Wittling F, Hartwig O, Federspiel J, Findji I, Walldorf U. Regulatory modules mediating the complex neural expression patterns of the homeobrain gene during Drosophila brain development. Hereditas 2022; 159:2. [PMID: 34983686 PMCID: PMC8728971 DOI: 10.1186/s41065-021-00218-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 12/10/2021] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND The homeobox gene homeobrain (hbn) is located in the 57B region together with two other homeobox genes, Drosophila Retinal homeobox (DRx) and orthopedia (otp). All three genes encode transcription factors with important functions in brain development. Hbn mutants are embryonic lethal and characterized by a reduction in the anterior protocerebrum, including the mushroom bodies, and a loss of the supraoesophageal brain commissure. RESULTS In this study we conducted a detailed expression analysis of Hbn in later developmental stages. In the larval brain, Hbn is expressed in all type II lineages and the optic lobes, including the medulla and lobula plug. The gene is expressed in the cortex of the medulla and the lobula rim in the adult brain. We generated a new hbnKOGal4 enhancer trap strain by reintegrating Gal4 in the hbn locus through gene targeting, which reflects the complete hbn expression during development. Eight different enhancer-Gal4 strains covering 12 kb upstream of hbn, the two large introns and 5 kb downstream of the gene, were established and hbn expression was investigated. We characterized several enhancers that drive expression in specific areas of the brain throughout development, from embryo to the adulthood. Finally, we generated deletions of four of these enhancer regions through gene targeting and analysed their effects on the expression and function of hbn. CONCLUSION The complex expression of Hbn in the developing brain is regulated by several specific enhancers within the hbn locus. Each enhancer fragment drives hbn expression in several specific cell lineages, and with largely overlapping patterns, suggesting the presence of shadow enhancers and enhancer redundancy. Specific enhancer deletion strains generated by gene targeting display developmental defects in the brain. This analysis opens an avenue for a deeper analysis of hbn regulatory elements in the future.
Collapse
Affiliation(s)
- Kirsten Hildebrandt
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Dieter Kolb
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Christine Klöppel
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Petra Kaspar
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
- Present address: COS Heidelberg, University of Heidelberg, Im Neuenheimer Feld 230, 69120, Heidelberg, Germany
| | - Fabienne Wittling
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
- Present address: Hemholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarland University, Building E8.1, 66123, Saarbrücken, Germany
| | - Olga Hartwig
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
- Present address: Hemholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarland University, Building E8.1, 66123, Saarbrücken, Germany
| | - Jannic Federspiel
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - India Findji
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Uwe Walldorf
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany.
| |
Collapse
|
9
|
Klöppel C, Hildebrandt K, Kolb D, Fürst N, Bley I, Karlowatz RJ, Walldorf U. Functional analysis of enhancer elements regulating the expression of the Drosophila homeodomain transcription factor DRx by gene targeting. Hereditas 2021; 158:42. [PMID: 34736520 PMCID: PMC8569992 DOI: 10.1186/s41065-021-00210-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/18/2021] [Indexed: 11/17/2022] Open
Abstract
Background The Drosophila brain is an ideal model system to study stem cells, here called neuroblasts, and the generation of neural lineages. Many transcriptional activators are involved in formation of the brain during the development of Drosophila melanogaster. The transcription factor Drosophila Retinal homeobox (DRx), a member of the 57B homeobox gene cluster, is also one of these factors for brain development. Results In this study a detailed expression analysis of DRx in different developmental stages was conducted. We show that DRx is expressed in the embryonic brain in the protocerebrum, in the larval brain in the DM and DL lineages, the medulla and the lobula complex and in the central complex of the adult brain. We generated a DRx enhancer trap strain by gene targeting and reintegration of Gal4, which mimics the endogenous expression of DRx. With the help of eight existing enhancer-Gal4 strains and one made by our group, we mapped various enhancers necessary for the expression of DRx during all stages of brain development from the embryo to the adult. We made an analysis of some larger enhancer regions by gene targeting. Deletion of three of these enhancers showing the most prominent expression patterns in the brain resulted in specific temporal and spatial loss of DRx expression in defined brain structures. Conclusion Our data show that DRx is expressed in specific neuroblasts and defined neural lineages and suggest that DRx is another important factor for Drosophila brain development. Supplementary Information The online version contains supplementary material available at 10.1186/s41065-021-00210-z.
Collapse
Affiliation(s)
- Christine Klöppel
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Kirsten Hildebrandt
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Dieter Kolb
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany
| | - Nora Fürst
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany.,Present address: Genetics/Epigenetics, Saarland University, Building A2.4, 66123, Saarbrücken, Germany
| | - Isabelle Bley
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany.,Present address: Research Institute Children's Cancer Center Hamburg, Building N63, Martinistr. 52, 20251, Hamburg, Germany
| | | | - Uwe Walldorf
- Developmental Biology, Saarland University, Building 61, 66421, Homburg/Saar, Germany.
| |
Collapse
|
10
|
Pham K, Masoudi N, Leyva-Díaz E, Hobert O. A nervous system-specific subnuclear organelle in Caenorhabditis elegans. Genetics 2021; 217:1-17. [PMID: 33683371 DOI: 10.1093/genetics/iyaa016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 11/12/2020] [Indexed: 12/26/2022] Open
Abstract
We describe here phase-separated subnuclear organelles in the nematode Caenorhabditis elegans, which we term NUN (NUclear Nervous system-specific) bodies. Unlike other previously described subnuclear organelles, NUN bodies are highly cell type specific. In fully mature animals, 4-10 NUN bodies are observed exclusively in the nucleus of neuronal, glial and neuron-like cells, but not in other somatic cell types. Based on co-localization and genetic loss of function studies, NUN bodies are not related to other previously described subnuclear organelles, such as nucleoli, splicing speckles, paraspeckles, Polycomb bodies, promyelocytic leukemia bodies, gems, stress-induced nuclear bodies, or clastosomes. NUN bodies form immediately after cell cycle exit, before other signs of overt neuronal differentiation and are unaffected by the genetic elimination of transcription factors that control many other aspects of neuronal identity. In one unusual neuron class, the canal-associated neurons, NUN bodies remodel during larval development, and this remodeling depends on the Prd-type homeobox gene ceh-10. In conclusion, we have characterized here a novel subnuclear organelle whose cell type specificity poses the intriguing question of what biochemical process in the nucleus makes all nervous system-associated cells different from cells outside the nervous system.
Collapse
Affiliation(s)
- Kenneth Pham
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA
| | - Neda Masoudi
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA
| | - Eduardo Leyva-Díaz
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA
| |
Collapse
|
11
|
Fujii T, Sakurai A, Littleton JT, Yoshihara M. Synaptotagmin 7 switches short-term synaptic plasticity from depression to facilitation by suppressing synaptic transmission. Sci Rep 2021; 11:4059. [PMID: 33603074 PMCID: PMC7892890 DOI: 10.1038/s41598-021-83397-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 01/22/2021] [Indexed: 01/25/2023] Open
Abstract
Short-term synaptic plasticity is a fast and robust modification in neuronal presynaptic output that can enhance release strength to drive facilitation or diminish it to promote depression. The mechanisms that determine whether neurons display short-term facilitation or depression are still unclear. Here we show that the Ca2+-binding protein Synaptotagmin 7 (Syt7) determines the sign of short-term synaptic plasticity by controlling the initial probability of synaptic vesicle (SV) fusion. Electrophysiological analysis of Syt7 null mutants at Drosophila embryonic neuromuscular junctions demonstrate loss of the protein converts the normally observed synaptic facilitation response during repetitive stimulation into synaptic depression. In contrast, overexpression of Syt7 dramatically enhanced the magnitude of short-term facilitation. These changes in short-term plasticity were mirrored by corresponding alterations in the initial evoked response, with SV release probability enhanced in Syt7 mutants and suppressed following Syt7 overexpression. Indeed, Syt7 mutants were able to display facilitation in lower [Ca2+] where release was reduced. These data suggest Syt7 does not act by directly sensing residual Ca2+ and argues for the existence of a distinct Ca2+ sensor beyond Syt7 that mediates facilitation. Instead, Syt7 normally suppresses synaptic transmission to maintain an output range where facilitation is available to the neuron.
Collapse
Affiliation(s)
- Takaaki Fujii
- Memory Neurobiology Project, National Institute of Information and Communications Technology, Kobe, Japan
| | - Akira Sakurai
- Memory Neurobiology Project, National Institute of Information and Communications Technology, Kobe, Japan
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Biology, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Motojiro Yoshihara
- Memory Neurobiology Project, National Institute of Information and Communications Technology, Kobe, Japan.
| |
Collapse
|
12
|
Kolb D, Kaspar P, Klöppel C, Walldorf U. The Drosophila homeodomain transcription factor Homeobrain is involved in the formation of the embryonic protocerebrum and the supraesophageal brain commissure. Cells Dev 2021; 165:203657. [PMID: 33993980 DOI: 10.1016/j.cdev.2021.203657] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 12/06/2020] [Accepted: 12/09/2020] [Indexed: 11/28/2022]
Abstract
During the embryonic development of Drosophila melanogaster many transcriptional activators are involved in the formation of the embryonic brain. In our study we show that the transcription factor Homeobrain (Hbn), a member of the 57B homeobox gene cluster, is an additional factor involved in the formation of the embryonic Drosophila brain. Using a Hbn antibody and specific cell type markers a detailed expression analysis during embryonic brain development was conducted. We show that Hbn is expressed in several regions in the protocerebrum, including fibre tract founder cells closely associated with the supraesophageal brain commissure and also in the mushroom bodies. During the formation of the supraesophageal commissure, Hbn and FasII-positive founder cells build an interhemispheric bridge priming the commissure and thereby linking both brain hemispheres. The Hbn expression is restricted to neural but not glial cells in the embryonic brain. In a mutagenesis screen we generated two mutant hbn alleles that both show embryonic lethality. The phenotype of the hbn mutant alleles is characterized by a reduction of the protocerebrum, a loss of the supraesophageal commissure and mushroom body progenitors and also by a dislocation of the optic lobes. Extensive apoptosis correlates with the impaired formation of the embryonic protocerebrum and the supraesophageal commissure. Our results show that Hbn is another important factor for embryonic brain development in Drosophila melanogaster.
Collapse
Affiliation(s)
- Dieter Kolb
- Developmental Biology, Saarland University, Building 61, 66421 Homburg/Saar, Germany
| | - Petra Kaspar
- Developmental Biology, Saarland University, Building 61, 66421 Homburg/Saar, Germany
| | - Christine Klöppel
- Developmental Biology, Saarland University, Building 61, 66421 Homburg/Saar, Germany
| | - Uwe Walldorf
- Developmental Biology, Saarland University, Building 61, 66421 Homburg/Saar, Germany.
| |
Collapse
|
13
|
Carrasco J, Rauer M, Hummel B, Grzejda D, Alfonso-Gonzalez C, Lee Y, Wang Q, Puchalska M, Mittler G, Hilgers V. ELAV and FNE Determine Neuronal Transcript Signatures through EXon-Activated Rescue. Mol Cell 2020; 80:156-163.e6. [PMID: 33007255 DOI: 10.1016/j.molcel.2020.09.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/03/2020] [Accepted: 08/12/2020] [Indexed: 12/22/2022]
Abstract
The production of alternative RNA variants contributes to the tissue-specific regulation of gene expression. In the animal nervous system, a systematic shift toward distal sites of transcription termination produces transcript signatures that are crucial for neuron development and function. Here, we report that, in Drosophila, the highly conserved protein ELAV globally regulates all sites of neuronal 3' end processing and directly binds to proximal polyadenylation sites of target mRNAs in vivo. We uncover an endogenous strategy of functional gene rescue that safeguards neuronal RNA signatures in an ELAV loss-of-function context. When not directly repressed by ELAV, the transcript encoding the ELAV paralog FNE acquires a mini-exon, generating a new protein able to translocate to the nucleus and rescue ELAV-mediated alternative polyadenylation and alternative splicing. We propose that exon-activated functional rescue is a more widespread mechanism that ensures robustness of processes regulated by a hierarchy, rather than redundancy, of effectors.
Collapse
Affiliation(s)
- Judit Carrasco
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Faculty of Biology, Albert Ludwig University, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology (IMPRS-MCB), 79108 Freiburg, Germany
| | - Michael Rauer
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Barbara Hummel
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Dominika Grzejda
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Faculty of Biology, Albert Ludwig University, 79104 Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology (IMPRS-MCB), 79108 Freiburg, Germany
| | - Carlos Alfonso-Gonzalez
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; Faculty of Biology, Albert Ludwig University, 79104 Freiburg, Germany; International Max Planck Research School for Immunology, Epigenetics and Metabolism (IMPRS-IEM), 79108 Freiburg, Germany
| | - Yeon Lee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Qingqing Wang
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Monika Puchalska
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Gerhard Mittler
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Valérie Hilgers
- Max-Planck-Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany.
| |
Collapse
|
14
|
Kinetochore protein Spindly controls microtubule polarity in Drosophila axons. Proc Natl Acad Sci U S A 2020; 117:12155-12163. [PMID: 32430325 DOI: 10.1073/pnas.2005394117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Microtubule polarity in axons and dendrites defines the direction of intracellular transport in neurons. Axons contain arrays of uniformly polarized microtubules with plus-ends facing the tips of the processes (plus-end-out), while dendrites contain microtubules with a minus-end-out orientation. It has been shown that cytoplasmic dynein, targeted to cortical actin, removes minus-end-out microtubules from axons. Here we have identified Spindly, a protein known for recruitment of dynein to kinetochores in mitosis, as a key factor required for dynein-dependent microtubule sorting in axons of Drosophila neurons. Depletion of Spindly affects polarity of axonal microtubules in vivo and in primary neuronal cultures. In addition to these defects, depletion of Spindly in neurons causes major collapse of axonal patterning in the third-instar larval brain as well as severe coordination impairment in adult flies. These defects can be fully rescued by full-length Spindly, but not by variants with mutations in its dynein-binding site. Biochemical analysis demonstrated that Spindly binds F-actin, suggesting that Spindly serves as a link between dynein and cortical actin in axons. Therefore, Spindly plays a critical role during neurodevelopment by mediating dynein-driven sorting of axonal microtubules.
Collapse
|
15
|
Waddell EA, Viveiros JM, Robinson EL, Sharoni MA, Latcheva NK, Marenda DR. Extramacrochaetae promotes branch and bouton number via the sequestration of daughterless in the cytoplasm of neurons. Dev Neurobiol 2019; 79:805-818. [PMID: 31581354 DOI: 10.1002/dneu.22720] [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: 07/10/2019] [Revised: 09/18/2019] [Accepted: 09/28/2019] [Indexed: 11/09/2022]
Abstract
The Class I basic helix-loop-helix (bHLH) proteins are highly conserved transcription factors that are ubiquitously expressed. A wealth of literature on Class I bHLH proteins has shown that these proteins must homodimerize or heterodimerize with tissue-specific HLH proteins in order to bind DNA at E-box consensus sequences to control tissue-specific transcription. Due to its ubiquitous expression, Class I bHLH proteins are also extensively regulated posttranslationally, mostly through dimerization. Previously, we reported that in addition to its role in promoting neurogenesis, the Class I bHLH protein daughterless also functions in mature neurons to restrict axon branching and synapse number. Here, we show that part of the molecular logic that specifies how daughterless functions in neurogenesis is also conserved in neurons. We show that the Type V HLH protein extramacrochaetae (Emc) binds to and represses daughterless function by sequestering daughterless to the cytoplasm. This work provides initial insights into the mechanisms underlying the function of daughterless and Emc in neurons while providing a novel understanding of how Emc functions to restrict daughterless activity within the cell.
Collapse
Affiliation(s)
- Edward A Waddell
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | | | - Erin L Robinson
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Michal A Sharoni
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Nina K Latcheva
- Department of Biology, Drexel University, Philadelphia, Pennsylvania
| | - Daniel R Marenda
- Department of Biology, Drexel University, Philadelphia, Pennsylvania.,Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| |
Collapse
|
16
|
del Castillo U, Gnazzo MM, Turpin CGS, Nguyen KCQ, Semaya E, Lam Y, de Cruz MA, Bembenek JN, Hall DH, Riggs B, Gelfand VI, Skop AR. Conserved role for Ataxin-2 in mediating endoplasmic reticulum dynamics. Traffic 2019; 20:436-447. [PMID: 30989774 PMCID: PMC6553494 DOI: 10.1111/tra.12647] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 12/17/2022]
Abstract
Ataxin-2, a conserved RNA-binding protein, is implicated in the late-onset neurodegenerative disease Spinocerebellar ataxia type-2 (SCA2). SCA2 is characterized by shrunken dendritic arbors and torpedo-like axons within the Purkinje neurons of the cerebellum. Torpedo-like axons have been described to contain displaced endoplasmic reticulum (ER) in the periphery of the cell; however, the role of Ataxin-2 in mediating ER function in SCA2 is unclear. We utilized the Caenorhabditis elegans and Drosophila homologs of Ataxin-2 (ATX-2 and DAtx2, respectively) to determine the role of Ataxin-2 in ER function and dynamics in embryos and neurons. Loss of ATX-2 and DAtx2 resulted in collapse of the ER in dividing embryonic cells and germline, and ultrastructure analysis revealed unique spherical stacks of ER in mature oocytes and fragmented and truncated ER tubules in the embryo. ATX-2 and DAtx2 reside in puncta adjacent to the ER in both C. elegans and Drosophila embryos. Lastly, depletion of DAtx2 in cultured Drosophila neurons recapitulated the shrunken dendritic arbor phenotype of SCA2. ER morphology and dynamics were severely disrupted in these neurons. Taken together, we provide evidence that Ataxin-2 plays an evolutionary conserved role in ER dynamics and morphology in C. elegans and Drosophila embryos during development and in fly neurons, suggesting a possible SCA2 disease mechanism.
Collapse
Affiliation(s)
- Urko del Castillo
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611
| | - Megan M. Gnazzo
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706
| | - Christopher G. Sorensen Turpin
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee 37996
| | - Ken C. Q. Nguyen
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Emily Semaya
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Yuwan Lam
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Matthew A. de Cruz
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Joshua N. Bembenek
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee 37996
| | - David H. Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Blake Riggs
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Vladimir I. Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611
| | - Ahna R. Skop
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706
| |
Collapse
|
17
|
Guo X, Zhang S, Lu S, Zheng B, Xie P, Chen J, Li G, Liu C, Wu Q, Cheng H, Sang N. Perfluorododecanoic acid exposure induced developmental neurotoxicity in zebrafish embryos. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 241:1018-1026. [PMID: 30029309 DOI: 10.1016/j.envpol.2018.06.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 06/04/2018] [Accepted: 06/04/2018] [Indexed: 06/08/2023]
Abstract
Perfluorododecanoic acid (PFDoA), an artificial perfluorochemical, has been widely distributed in different ambient media and has been reported to have the potential to cause developmental neurotoxicity. However, the specific mechanism is largely unknown. In the current study, zebrafish embryos were treated with 0, 0.24, 1.2, and 6 mg/L PFDoA for 120 h. Exposure to PFDoA causes serious decreases in hatching delay, body length, as well as decreased locomotor speed in zebrafish larvae. Additionally, the acetylcholine (ACh) content as well as acetylcholinesterase (AChE) activity were determined to be significantly downregulated in PFDoA treatment groups. The level of dopamine was upregulated significantly after treating with 1.2 and 6 mg/L of PFDoA. Gene expressions related to the nervous system development were also analyzed, with the exception of the gene mesencephalic astrocyte-derived neurotrophic factor (manf), which is upregulated in the 6 mg/L treatment group. All other genes were significantly downregulated in larvae in the PFDoA group in different degrees. In general, the results demonstrated that PFDoA exposure could result in the disruption of the cholinergic system, dopaminergic signaling, and the central nervous system.
Collapse
Affiliation(s)
- Xiaochun Guo
- State Environmental Protection Scientific Observation and Research Station for Lake Dongtinghu (SEPSORSLD), National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
| | - Shengnan Zhang
- State Environmental Protection Scientific Observation and Research Station for Lake Dongtinghu (SEPSORSLD), National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; College of Environment and Resource, Shanxi University, Taiyuan, 030006, China
| | - Shaoyong Lu
- State Environmental Protection Scientific Observation and Research Station for Lake Dongtinghu (SEPSORSLD), National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
| | - Binghui Zheng
- State Environmental Protection Scientific Observation and Research Station for Lake Dongtinghu (SEPSORSLD), National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Ping Xie
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Jun Chen
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Guangyu Li
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Chunsheng Liu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qin Wu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Houcheng Cheng
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Nan Sang
- College of Environment and Resource, Shanxi University, Taiyuan, 030006, China
| |
Collapse
|
18
|
Abstract
Several lineages of symbiotic bacteria in insects selfishly manipulate host reproduction to spread in a population 1 , often by distorting host sex ratios. Spiroplasma poulsonii2,3 is a helical and motile, Gram-positive symbiotic bacterium that resides in a wide range of Drosophila species 4 . A notable feature of S. poulsonii is male killing, whereby the sons of infected female hosts are selectively killed during development1,2. Although male killing caused by S. poulsonii has been studied since the 1950s, its underlying mechanism is unknown. Here we identify an S. poulsonii protein, designated Spaid, whose expression induces male killing. Overexpression of Spaid in D. melanogaster kills males but not females, and induces massive apoptosis and neural defects, recapitulating the pathology observed in S. poulsonii-infected male embryos5-11. Our data suggest that Spaid targets the dosage compensation machinery on the male X chromosome to mediate its effects. Spaid contains ankyrin repeats and a deubiquitinase domain, which are required for its subcellular localization and activity. Moreover, we found a laboratory mutant strain of S. poulsonii with reduced male-killing ability and a large deletion in the spaid locus. Our study has uncovered a bacterial protein that affects host cellular machinery in a sex-specific way, which is likely to be the long-searched-for factor responsible for S. poulsonii-induced male killing.
Collapse
|
19
|
Ye Y, Li M, Gu L, Chen X, Shi J, Zhang X, Jiang C. Chromatin remodeling during in vivo neural stem cells differentiating to neurons in early Drosophila embryos. Cell Death Differ 2016; 24:409-420. [PMID: 27858939 PMCID: PMC5344203 DOI: 10.1038/cdd.2016.135] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 10/06/2016] [Accepted: 10/18/2016] [Indexed: 12/25/2022] Open
Abstract
Neurons are a key component of the nervous system and differentiate from multipotent neural stem cells (NSCs). Chromatin remodeling has a critical role in the differentiation process. However, its in vivo epigenetic regulatory role remains unknown. We show here that nucleosome depletion regions (NDRs) form in both proximal promoters and distal enhancers during NSCs differentiating into neurons in the early Drosophila embryonic development. NDR formation in the regulatory regions involves nucleosome shift and eviction. Nucleosome occupancy in promoter NDRs is inversely proportional to the gene activity. Genes with promoter NDR formation during differentiation are enriched for functions related to neuron development and maturation. Active histone-modification signals (H3K4me3 and H3K9ac) in promoters are gained in neurons in two modes: de novo establishment to high levels or increase from the existing levels in NSCs. The gene sets corresponding to the two modes have different neuron-related functions. Dynamic changes of H3K27ac and H3K9ac signals in enhancers and promoters synergistically repress genes associated with neural stem or progenitor cell-related pluripotency and upregulate genes associated with neuron projection morphogenesis, neuron differentiation, and so on. Our results offer new insights into chromatin remodeling during in vivo neuron development and lay a foundation for its epigenetic regulatory mechanism study of other lineage specification.
Collapse
Affiliation(s)
- Youqiong Ye
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai Key Laboratory of Signaling and Disease Research, The School of Life Sciences and Technology, The Collaborative Innovation Center for Brain Science, Tongji University, Shanghai 200092, China
| | - Min Li
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai Key Laboratory of Signaling and Disease Research, The School of Life Sciences and Technology, The Collaborative Innovation Center for Brain Science, Tongji University, Shanghai 200092, China
| | - Liang Gu
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai Key Laboratory of Signaling and Disease Research, The School of Life Sciences and Technology, The Collaborative Innovation Center for Brain Science, Tongji University, Shanghai 200092, China
| | - Xiaolong Chen
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai Key Laboratory of Signaling and Disease Research, The School of Life Sciences and Technology, The Collaborative Innovation Center for Brain Science, Tongji University, Shanghai 200092, China
| | - Jiejun Shi
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai Key Laboratory of Signaling and Disease Research, The School of Life Sciences and Technology, The Collaborative Innovation Center for Brain Science, Tongji University, Shanghai 200092, China
| | - Xiaobai Zhang
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai Key Laboratory of Signaling and Disease Research, The School of Life Sciences and Technology, The Collaborative Innovation Center for Brain Science, Tongji University, Shanghai 200092, China
| | - Cizhong Jiang
- Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai Key Laboratory of Signaling and Disease Research, The School of Life Sciences and Technology, The Collaborative Innovation Center for Brain Science, Tongji University, Shanghai 200092, China
| |
Collapse
|
20
|
Sanfilippo P, Smibert P, Duan H, Lai EC. Neural specificity of the RNA-binding protein Elav is achieved by post-transcriptional repression in non-neural tissues. Development 2016; 143:4474-4485. [PMID: 27802174 DOI: 10.1242/dev.141978] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 10/12/2016] [Indexed: 12/22/2022]
Abstract
Drosophila Elav is the founding member of the conserved family of Hu RNA-binding proteins (RBPs), which play crucial and diverse roles in post-transcriptional regulation. Elav has long served as the canonical neuronal marker. Surprisingly, although Elav has a well-characterized neural cis-regulatory module, we find endogenous Elav is also ubiquitously transcribed and post-transcriptionally repressed in non-neural settings. Mutant clones of multiple miRNA pathway components derepress ubiquitous Elav protein. Our re-annotation of the elav transcription unit shows not only that it generates extended 3' UTR isoforms, but also that its universal 3' UTR isoform is much longer than previously believed. This longer common 3' UTR includes multiple conserved, high-affinity sites for the miR-279/996 family. Of several miRNA mutants tested, endogenous Elav and a transgenic elav 3' UTR sensor are derepressed in mutant clones of mir-279/996 We also observe cross-repression of Elav by Mei-P26, another RBP derepressed in non-neural miRNA pathway clones. Ubiquitous Elav has regulatory capacity, since derepressed Elav can stabilize an Elav-responsive sensor. Repression of Elav in non-neural territories is crucial as misexpression here has profoundly adverse consequences. Altogether, we define unexpected post-transcriptional mechanisms that direct appropriate cell type-specific expression of a conserved neural RBP.
Collapse
Affiliation(s)
- Piero Sanfilippo
- Sloan-Kettering Institute, Department of Developmental Biology, 1275 York Ave, Box 252, New York, NY 10065, USA.,Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Peter Smibert
- Sloan-Kettering Institute, Department of Developmental Biology, 1275 York Ave, Box 252, New York, NY 10065, USA
| | - Hong Duan
- Sloan-Kettering Institute, Department of Developmental Biology, 1275 York Ave, Box 252, New York, NY 10065, USA
| | - Eric C Lai
- Sloan-Kettering Institute, Department of Developmental Biology, 1275 York Ave, Box 252, New York, NY 10065, USA .,Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| |
Collapse
|
21
|
Role of kinesin-1-based microtubule sliding in Drosophila nervous system development. Proc Natl Acad Sci U S A 2016; 113:E4985-94. [PMID: 27512046 DOI: 10.1073/pnas.1522416113] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The plus-end microtubule (MT) motor kinesin-1 is essential for normal development, with key roles in the nervous system. Kinesin-1 drives axonal transport of membrane cargoes to fulfill the metabolic needs of neurons and maintain synapses. We have previously demonstrated that kinesin-1, in addition to its well-established role in organelle transport, can drive MT-MT sliding by transporting "cargo" MTs along "track" MTs, resulting in dramatic cell shape changes. The mechanism and physiological relevance of this MT sliding are unclear. In addition to its motor domain, kinesin-1 contains a second MT-binding site, located at the C terminus of the heavy chain. Here, we mutated this C-terminal MT-binding site such that the ability of kinesin-1 to slide MTs is significantly compromised, whereas cargo transport is unaffected. We introduced this mutation into the genomic locus of kinesin-1 heavy chain (KHC), generating the Khc(mutA) allele. Khc(mutA) neurons displayed significant MT sliding defects while maintaining normal transport of many cargoes. Using this mutant, we demonstrated that MT sliding is required for axon and dendrite outgrowth in vivo. Consistent with these results, Khc(mutA) flies displayed severe locomotion and viability defects. To test the role of MT sliding further, we engineered a chimeric motor that actively slides MTs but cannot transport organelles. Activation of MT sliding in Khc(mutA) neurons using this chimeric motor rescued axon outgrowth in cultured neurons and in vivo, firmly establishing the role of sliding in axon outgrowth. These results demonstrate that MT sliding by kinesin-1 is an essential biological phenomenon required for neuronal morphogenesis and normal nervous system development.
Collapse
|
22
|
Bandyopadhyay M, Bishop CP, Bidwai AP. The Conserved MAPK Site in E(spl)-M8, an Effector of Drosophila Notch Signaling, Controls Repressor Activity during Eye Development. PLoS One 2016; 11:e0159508. [PMID: 27428327 PMCID: PMC4948772 DOI: 10.1371/journal.pone.0159508] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/05/2016] [Indexed: 12/12/2022] Open
Abstract
The specification of patterned R8 photoreceptors at the onset of eye development depends on timely inhibition of Atonal (Ato) by the Enhancer of split (E(spl) repressors. Repression of Ato by E(spl)-M8 requires the kinase CK2 and is inhibited by the phosphatase PP2A. The region targeted by CK2 harbors additional conserved Ser residues, raising the prospect of regulation via multi-site phosphorylation. Here we investigate one such motif that meets the consensus for modification by MAPK, a well-known effector of Epidermal Growth Factor Receptor (EGFR) signaling. Our studies reveal an important role for the predicted MAPK site of M8 during R8 birth. Ala/Asp mutations reveal that the CK2 and MAPK sites ensure that M8 repression of Ato and the R8 fate occurs in a timely manner and at a specific stage (stage-2/3) of the morphogenetic furrow (MF). M8 repression of Ato is mitigated by halved EGFR dosage, and this effect requires an intact MAPK site. Accordingly, variants with a phosphomimetic Asp at the MAPK site exhibit earlier (inappropriate) activity against Ato even at stage-1 of the MF, where a positive feedback-loop is necessary to raise Ato levels to a threshold sufficient for the R8 fate. Analysis of deletion variants reveals that both kinase sites (CK2 and MAPK) contribute to ‘cis’-inhibition of M8. This key regulation by CK2 and MAPK is bypassed by the E(spl)D mutation encoding the truncated protein M8*, which potently inhibits Ato at stage-1 of R8 birth. We also provide evidence that PP2A likely targets the MAPK site. Thus multi-site phosphorylation controls timely onset of M8 repressor activity in the eye, a regulation that appears to be dispensable in the bristle. The high conservation of the CK2 and MAPK sites in the insect E(spl) proteins M7, M5 and Mγ, and their mammalian homologue HES6, suggest that this mode of regulation may enable E(spl)/HES proteins to orchestrate repression by distinct tissue-specific mechanisms, and is likely to have broader applicability than has been previously recognized.
Collapse
Affiliation(s)
- Mohna Bandyopadhyay
- Department of Biology, West Virginia University, Morgantown, West Virginia, United States of America
| | - Clifton P. Bishop
- Department of Biology, West Virginia University, Morgantown, West Virginia, United States of America
| | - Ashok P. Bidwai
- Department of Biology, West Virginia University, Morgantown, West Virginia, United States of America
- * E-mail:
| |
Collapse
|
23
|
Regulation of Stem Cell Self-Renewal and Oncogenesis by RNA-Binding Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 907:153-88. [PMID: 27256386 DOI: 10.1007/978-3-319-29073-7_7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Throughout their life span, multicellular organisms rely on stem cell systems. During development pluripotent embryonic stem cells give rise to all cell types that make up the organism. After birth, tissue stem cells maintain properly functioning tissues and organs under homeostasis as well as promote regeneration after tissue damage or injury. Stem cells are capable of self-renewal, which is the ability to divide indefinitely while retaining the potential of differentiation into multiple cell types. The ability to self-renew, however, is a double-edged sword; the molecular mechanisms of self-renewal can be a target of malignant transformation driving tumor development and progression. Growing lines of evidence have shown that RNA-binding proteins (RBPs) play pivotal roles in the regulation of self-renewal by modulating metabolism of coding and non-coding RNAs both in normal tissues and in cancers. In this review, we discuss our current understanding of tissue stem cell systems and how RBPs regulate stem cell fates as well as how the regulatory functions of RBPs contribute to oncogenesis.
Collapse
|
24
|
Leo L, Yu W, D'Rozario M, Waddell EA, Marenda DR, Baird MA, Davidson MW, Zhou B, Wu B, Baker L, Sharp DJ, Baas PW. Vertebrate Fidgetin Restrains Axonal Growth by Severing Labile Domains of Microtubules. Cell Rep 2015; 12:1723-30. [PMID: 26344772 PMCID: PMC4837332 DOI: 10.1016/j.celrep.2015.08.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/17/2015] [Accepted: 08/05/2015] [Indexed: 12/27/2022] Open
Abstract
Individual microtubules (MTs) in the axon consist of a stable domain that is highly acetylated and a labile domain that is not. Traditional MT-severing proteins preferentially cut the MT in the stable domain. In Drosophila, fidgetin behaves in this fashion, with targeted knockdown resulting in neurons with a higher fraction of acetylated (stable) MT mass in their axons. Conversely, in a fidgetin knockout mouse, the fraction of MT mass that is acetylated is lower than in the control animal. When fidgetin is depleted from cultured rodent neurons, there is a 62% increase in axonal MT mass, all of which is labile. Concomitantly, there are more minor processes and a longer axon. Together with experimental data showing that vertebrate fidgetin targets unacetylated tubulin, these results indicate that vertebrate fidgetin (unlike its fly ortholog) regulates neuronal development by tamping back the expansion of the labile domains of MTs.
Collapse
Affiliation(s)
- Lanfranco Leo
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Wenqian Yu
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | | | - Edward A Waddell
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Daniel R Marenda
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA; Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Michelle A Baird
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, FL 32310, USA
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, FL 32310, USA
| | - Bin Zhou
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Bingro Wu
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Lisa Baker
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - David J Sharp
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
| |
Collapse
|
25
|
Mosher J, Zhang W, Blumhagen RZ, D'Alessandro A, Nemkov T, Hansen KC, Hesselberth JR, Reis T. Coordination between Drosophila Arc1 and a specific population of brain neurons regulates organismal fat. Dev Biol 2015. [PMID: 26209258 DOI: 10.1016/j.ydbio.2015.07.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The brain plays a critical yet incompletely understood role in regulating organismal fat. We performed a neuronal silencing screen in Drosophila larvae to identify brain regions required to maintain proper levels of organismal fat. When used to modulate synaptic activity in specific brain regions, the enhancer-trap driver line E347 elevated fat upon neuronal silencing, and decreased fat upon neuronal activation. Unbiased sequencing revealed that Arc1 mRNA levels increase upon E347 activation. We had previously identified Arc1 mutations in a high-fat screen. Here we reveal metabolic changes in Arc1 mutants consistent with a high-fat phenotype and an overall shift toward energy storage. We find that Arc1-expressing cells neighbor E347 neurons, and manipulating E347 synaptic activity alters Arc1 expression patterns. Elevating Arc1 expression in these cells decreased fat, a phenocopy of E347 activation. Finally, loss of Arc1 prevented the lean phenotype caused by E347 activation, suggesting that Arc1 activity is required for E347 control of body fat. Importantly, neither E347 nor Arc1 manipulation altered energy-related behaviors. Our results support a model wherein E347 neurons induce Arc1 in specific neighboring cells to prevent excess fat accumulation.
Collapse
Affiliation(s)
- Jeremy Mosher
- Department of Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Colorado Medical School, Aurora, CO 80045, United States
| | - Wei Zhang
- Department of Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Colorado Medical School, Aurora, CO 80045, United States
| | - Rachel Z Blumhagen
- Department of Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Colorado Medical School, Aurora, CO 80045, United States
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado Medical School, Aurora, CO 80045, United States
| | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, University of Colorado Medical School, Aurora, CO 80045, United States
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado Medical School, Aurora, CO 80045, United States
| | - Jay R Hesselberth
- Department of Biochemistry and Molecular Genetics, University of Colorado Medical School, Aurora, CO 80045, United States
| | - Tânia Reis
- Department of Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Colorado Medical School, Aurora, CO 80045, United States.
| |
Collapse
|
26
|
Lu W, Lakonishok M, Gelfand VI. Kinesin-1-powered microtubule sliding initiates axonal regeneration in Drosophila cultured neurons. Mol Biol Cell 2015; 26:1296-307. [PMID: 25657321 PMCID: PMC4454177 DOI: 10.1091/mbc.e14-10-1423] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Microtubule sliding drives initial axon regeneration in Drosophila neurons. Axotomy leads to fast calcium influx and subsequent microtubule reorganization. Kinesin-1 heavy chain drives the sliding of antiparallel microtubules to power axonal regrowth, and the JNK pathway promotes axonal regeneration by enhancing microtubule sliding. Understanding the mechanism underlying axon regeneration is of great practical importance for developing therapeutic treatment for traumatic brain and spinal cord injuries. Dramatic cytoskeleton reorganization occurs at the injury site, and microtubules have been implicated in the regeneration process. Previously we demonstrated that microtubule sliding by conventional kinesin (kinesin-1) is required for initiation of neurite outgrowth in Drosophila embryonic neurons and that sliding is developmentally down-regulated when neurite outgrowth is completed. Here we report that mechanical axotomy of Drosophila neurons in culture triggers axonal regeneration and regrowth. Regenerating neurons contain actively sliding microtubules; this sliding, like sliding during initial neurite outgrowth, is driven by kinesin-1 and is required for axonal regeneration. The injury induces a fast spike of calcium, depolymerization of microtubules near the injury site, and subsequent formation of local new microtubule arrays with mixed polarity. These events are required for reactivation of microtubule sliding at the initial stages of regeneration. Furthermore, the c-Jun N-terminal kinase pathway promotes regeneration by enhancing microtubule sliding in injured mature neurons.
Collapse
Affiliation(s)
- Wen Lu
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Margot Lakonishok
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| |
Collapse
|
27
|
Freeman AA, Dai H, Sanyal S. Use of Drosophila to Study Restless Legs Syndrome. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00078-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
|
28
|
Del Castillo U, Lu W, Winding M, Lakonishok M, Gelfand VI. Pavarotti/MKLP1 regulates microtubule sliding and neurite outgrowth in Drosophila neurons. Curr Biol 2014; 25:200-205. [PMID: 25557664 DOI: 10.1016/j.cub.2014.11.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 10/03/2014] [Accepted: 11/04/2014] [Indexed: 11/16/2022]
Abstract
Recently, we demonstrated that kinesin-1 can slide microtubules against each other, providing the mechanical force required for initial neurite extension in Drosophila neurons. This sliding is only observed in young neurons actively forming neurites and is dramatically downregulated in older neurons. The downregulation is not caused by the global shutdown of kinesin-1, as the ability of kinesin-1 to transport membrane organelles is not diminished in mature neurons, suggesting that microtubule sliding is regulated by a dedicated mechanism. Here, we have identified the "mitotic" kinesin-6 Pavarotti (Pav-KLP) as an inhibitor of kinesin-1-driven microtubule sliding. Depletion of Pav-KLP in neurons strongly stimulated the sliding of long microtubules and neurite outgrowth, while its ectopic overexpression in the cytoplasm blocked both of these processes. Furthermore, postmitotic depletion of Pav-KLP in Drosophila neurons in vivo reduced embryonic and larval viability, with only a few animals surviving to the third instar larval stage. A detailed examination of motor neurons in the surviving larvae revealed the overextension of axons and mistargeting of neuromuscular junctions, resulting in uncoordinated locomotion. Taken together, our results identify a new role for Pav-KLP as a negative regulator of kinesin-1-driven neurite formation. These data suggest an important parallel between long microtubule-microtubule sliding in anaphase B and sliding of interphase microtubules during neurite formation.
Collapse
Affiliation(s)
- Urko Del Castillo
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Avenue, Chicago, IL 60611, USA; IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Spain
| | - Wen Lu
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Avenue, Chicago, IL 60611, USA
| | - Michael Winding
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Avenue, Chicago, IL 60611, USA
| | - Margot Lakonishok
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Avenue, Chicago, IL 60611, USA
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Avenue, Chicago, IL 60611, USA.
| |
Collapse
|
29
|
DeSalvo MK, Hindle SJ, Rusan ZM, Orng S, Eddison M, Halliwill K, Bainton RJ. The Drosophila surface glia transcriptome: evolutionary conserved blood-brain barrier processes. Front Neurosci 2014; 8:346. [PMID: 25426014 PMCID: PMC4224204 DOI: 10.3389/fnins.2014.00346] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/10/2014] [Indexed: 12/29/2022] Open
Abstract
Central nervous system (CNS) function is dependent on the stringent regulation of metabolites, drugs, cells, and pathogens exposed to the CNS space. Cellular blood-brain barrier (BBB) structures are highly specific checkpoints governing entry and exit of all small molecules to and from the brain interstitial space, but the precise mechanisms that regulate the BBB are not well understood. In addition, the BBB has long been a challenging obstacle to the pharmacologic treatment of CNS diseases; thus model systems that can parse the functions of the BBB are highly desirable. In this study, we sought to define the transcriptome of the adult Drosophila melanogaster BBB by isolating the BBB surface glia with fluorescence activated cell sorting (FACS) and profiling their gene expression with microarrays. By comparing the transcriptome of these surface glia to that of all brain glia, brain neurons, and whole brains, we present a catalog of transcripts that are selectively enriched at the Drosophila BBB. We found that the fly surface glia show high expression of many ATP-binding cassette (ABC) and solute carrier (SLC) transporters, cell adhesion molecules, metabolic enzymes, signaling molecules, and components of xenobiotic metabolism pathways. Using gene sequence-based alignments, we compare the Drosophila and Murine BBB transcriptomes and discover many shared chemoprotective and small molecule control pathways, thus affirming the relevance of invertebrate models for studying evolutionary conserved BBB properties. The Drosophila BBB transcriptome is valuable to vertebrate and insect biologists alike as a resource for studying proteins underlying diffusion barrier development and maintenance, glial biology, and regulation of drug transport at tissue barriers.
Collapse
Affiliation(s)
- Michael K DeSalvo
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| | - Samantha J Hindle
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| | - Zeid M Rusan
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| | - Souvinh Orng
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| | - Mark Eddison
- Janelia Farm Research Campus, The Howard Hughes Medical Institute Ashburn, VA, USA
| | - Kyle Halliwill
- Pharmaceutical Sciences and Pharmacogenomics, University of California San Francisco San Francisco, CA, USA
| | - Roland J Bainton
- Department of Anesthesia and Perioperative Care, University of California San Francisco San Francisco, CA, USA
| |
Collapse
|
30
|
Park KS, Kim SH, Jeon SH. A study of Drosophila spinster expression and its functions during embryogenesis. Genes Genomics 2014. [DOI: 10.1007/s13258-014-0219-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
31
|
The Ser/Thr phosphatase PP2A regulatory subunit widerborst inhibits notch signaling. PLoS One 2014; 9:e101884. [PMID: 25006677 PMCID: PMC4090204 DOI: 10.1371/journal.pone.0101884] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 06/12/2014] [Indexed: 01/23/2023] Open
Abstract
Drosophila Enhancer of split M8, an effector of Notch signaling, is regulated by protein kinase CK2. The phosphatase PP2A is thought to play an opposing (inhibitory) role, but the identity of the regulatory subunit was unknown. The studies described here reveal a role for the PP2A regulatory subunit widerborst (wdb) in three developmental contexts; the bristle, wing and the R8 photoreceptors of the eye. wdb overexpression elicits bristle and wing defects akin to reduced Notch signaling, whereas hypomorphic mutations in this PP2A subunit elicit opposite effects. We have also evaluated wdb functions using mutations in Notch and E(spl) that affect the eye. We find that the eye and R8 defects of the well-known Nspl mutation are enhanced by a hypomorphic allele of wdb, whereas they are strongly rescued by wdb overexpression. Similarly, ectopic wdb rescues the eye and R8 defects of the E(spl)D mutation, which affects the m8 gene. In addition, wdb overexpression also rescues the bristle defects of ectopically expressed M8, or the eye and R8 defects of its CK2 phosphomimetic variant M8-S159D. The latter finding suggests that PP2A may target M8 at highly conserved residues in the vicinity of the CK2 site, whose phosphorylation controls repression of Atonal and the R8 fate. Together, the studies identify PP2A-Wdb as a participant in Notch signaling, and suggest that M8 activity is controlled by phosphorylation and dephosphorylation. The conservation of the phosphorylation sites between Drosophila E(spl) and the HES/HER proteins from mammals, reptiles, amphibians, birds and fish raises the prospect that this mode of regulation is widespread.
Collapse
|
32
|
Direct Observation of ON and OFF Pathways in the Drosophila Visual System. Curr Biol 2014; 24:976-83. [DOI: 10.1016/j.cub.2014.03.017] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 02/28/2014] [Accepted: 03/06/2014] [Indexed: 01/14/2023]
|
33
|
Buresi A, Croll RP, Tiozzo S, Bonnaud L, Baratte S. Emergence of sensory structures in the developing epidermis in sepia officinalis and other coleoid cephalopods. J Comp Neurol 2014; 522:3004-19. [PMID: 24549606 DOI: 10.1002/cne.23562] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Revised: 02/10/2014] [Accepted: 02/10/2014] [Indexed: 11/11/2022]
Abstract
Embryonic cuttlefish can first respond to a variety of sensory stimuli during early development in the egg capsule. To examine the neural basis of this ability, we investigated the emergence of sensory structures within the developing epidermis. We show that the skin facing the outer environment (not the skin lining the mantle cavity, for example) is derived from embryonic domains expressing the Sepia officinalis ortholog of pax3/7, a gene involved in epidermis specification in vertebrates. On the head, they are confined to discrete brachial regions referred to as "arm pillars" that expand and cover Sof-pax3/7-negative head ectodermal tissues. As revealed by the expression of the S. officinalis ortholog of elav1, an early marker of neural differentiation, the olfactory organs first differentiate at about stage 16 within Sof-pax3/7-negative ectodermal regions before they are covered by the definitive Sof-pax3/7-positive outer epithelium. In contrast, the eight mechanosensory lateral lines running over the head surface and the numerous other putative sensory cells in the epidermis, differentiate in the Sof-pax3/7-positive tissues at stages ∼24-25, after they have extended over the entire outer surfaces of the head and arms. Locations and morphologies of the various sensory cells in the olfactory organs and skin were examined using antibodies against acetylated tubulin during the development of S. officinalis and were compared with those in hatchlings of two other cephalopod species. The early differentiation of olfactory structures and the peculiar development of the epidermis with its sensory cells provide new perspectives for comparisons of developmental processes among molluscs.
Collapse
Affiliation(s)
- Auxane Buresi
- Museum National d'Histoire Naturelle (MNHN), DMPA, UMR Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN CNRS 7208, IRD 207, UPMC, CP51 75005, Paris, France; Université Pierre et Marie Curie-Paris, Paris, 6, France
| | | | | | | | | |
Collapse
|
34
|
Watanabe T, Aonuma H. Tissue-specific promoter usage and diverse splicing variants of found in neurons, an ancestral Hu/ELAV-like RNA-binding protein gene of insects, in the direct-developing insect Gryllus bimaculatus. INSECT MOLECULAR BIOLOGY 2014; 23:26-41. [PMID: 24382152 DOI: 10.1111/imb.12057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Hu/ELAV-like RNA-binding proteins (RBPs) are involved in the post-transcriptional regulation of RNA metabolism including splicing, transport, translational control and turnover. The Hu/ELAV-like RBP genes are predominantly expressed in neurons, and are therefore used as common neuronal markers in many animals. Although the expression patterns and functions of the Hu/ELAV-like RBP genes have been extensively studied in the model insect Drosophila melanogaster, little is known in basal direct-developing insects. In the present study, we performed an identification and expression analysis of the found in neurons (fne) gene, an ancestral insect Hu/ELAV-like RBP gene, in the cricket Gryllus bimaculatus. Contrary to expectation that the Gryllus fne transcript would be predominantly expressed in the nervous system, expression analysis revealed that the Gryllus fne gene is expressed broadly. In addition, we discovered that alternative promoter usage directs tissue-specific and embryonic stage-dependent regulation of fne expression, and that alternative splicing contributes to the generation of diverse sets of fne transcripts. Our data provide novel insights into the evolutionary diversification of the Hu/ELAV-like RBP gene family in insects.
Collapse
Affiliation(s)
- T Watanabe
- Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan
| | | |
Collapse
|
35
|
Buresi A, Canali E, Bonnaud L, Baratte S. Delayed and asynchronous ganglionic maturation during cephalopod neurogenesis as evidenced by Sof-elav1 expression in embryos of Sepia officinalis (Mollusca, Cephalopoda). J Comp Neurol 2013; 521:1482-96. [PMID: 23047428 DOI: 10.1002/cne.23231] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/27/2012] [Accepted: 10/02/2012] [Indexed: 01/05/2023]
Abstract
Among the Lophotrochozoa, centralization of the nervous system reaches an exceptional level of complexity in cephalopods, where the typical molluscan ganglia become highly developed and fuse into hierarchized lobes. It is known that ganglionic primordia initially emerge early and simultaneously during cephalopod embryogenesis but no data exist on the process of neuron differentiation in this group. We searched for members of the elav/hu family in the cuttlefish Sepia officinalis, since they are one of the first genetic markers of postmitotic neural cells. Two paralogs were identified and the expression of the most neural-specific gene, Sof-elav1, was characterized during embryogenesis. Sof-elav1 is expressed in all ganglia at one time of development, which provides the first genetic map of neurogenesis in a cephalopod. Our results unexpectedly revealed that Sof-elav1 expression is not similar and not coordinated in all the prospective ganglia. Both palliovisceral ganglia show extensive Sof-elav1 expression soon after emergence, showing that most of their cells differentiate into neurons at an early stage. On the contrary, other ganglia, and especially both cerebral ganglia that contribute to the main parts of the brain learning centers, show a late extensive Sof-elav1 expression. These delayed expressions in ganglia suggest that most ganglionic cells retain their proliferative capacities and postpone differentiation. In other molluscs, where a larval nervous system predates the development of the definitive adult nervous system, cerebral ganglia are among the first to mature. Thus, such a difference may constitute a cue in understanding the peculiar brain evolution in cephalopods.
Collapse
Affiliation(s)
- Auxane Buresi
- Muséum National d'Histoire Naturelle (MNHN), DMPA, UMR Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN CNRS 7208, IRD 207, UPMC, 75005 Paris, France.
| | | | | | | |
Collapse
|
36
|
Schulte C, Leboulle G, Otte M, Grünewald B, Gehne N, Beye M. Honey bee promoter sequences for targeted gene expression. INSECT MOLECULAR BIOLOGY 2013; 22:399-410. [PMID: 23668189 DOI: 10.1111/imb.12031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The honey bee, Apis mellifera, displays a rich behavioural repertoire, social organization and caste differentiation, and has an interesting mode of sex determination, but we still know little about its underlying genetic programs. We lack stable transgenic tools in honey bees that would allow genetic control of gene activity in stable transgenic lines. As an initial step towards a transgenic method, we identified promoter sequences in the honey bee that can drive constitutive, tissue-specific and cold shock-induced gene expression. We identified the promoter sequences of Am-actin5c, elp2l, Am-hsp83 and Am-hsp70 and showed that, except for the elp2l sequence, the identified sequences were able to drive reporter gene expression in Sf21 cells. We further demonstrated through electroporation experiments that the putative neuron-specific elp2l promoter sequence can direct gene expression in the honey bee brain. The identification of these promoter sequences is an important initial step in studying the function of genes with transgenic experiments in the honey bee, an organism with a rich set of interesting phenotypes.
Collapse
Affiliation(s)
- C Schulte
- Institute of Evolutionary Genetics, Heinrich Heine University Duesseldorf, Duesseldorf, Germany.
| | | | | | | | | | | |
Collapse
|
37
|
Post-transcriptional regulatory elements and spatiotemporal specification of neocortical stem cells and projection neurons. Neuroscience 2013; 248:499-528. [PMID: 23727006 DOI: 10.1016/j.neuroscience.2013.05.042] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 05/15/2013] [Accepted: 05/21/2013] [Indexed: 11/22/2022]
Abstract
The mature neocortex is a unique six-layered mammalian brain region. It is composed of morphologically and functionally distinct subpopulations of primary projection neurons that form complex circuits across the central nervous system. The precisely-timed generation of projection neurons from neural stem cells governs their differentiation, postmitotic specification, and signaling, and is critical for cognitive and sensorimotor ability. Developmental perturbations to the birthdate, location, and connectivity of neocortical neurons are observed in neurological and psychiatric disorders. These facts are highlighting the importance of the precise spatiotemporal development of the neocortex regulated by intricate transcriptional, but also complex post-transcriptional events. Indeed, mRNA transcripts undergo many post-transcriptional regulatory steps before the production of functional proteins, which specify neocortical neural stem cells and subpopulations of neocortical neurons. Therefore, particular attention is paid to the differential post-transcriptional regulation of key transcripts by RNA-binding proteins, including splicing, localization, stability, and translation. We also present a transcriptome screen of candidate molecules associated with post-transcriptional mRNA processing that are differentially expressed at key developmental time points across neocortical prenatal neurogenesis.
Collapse
|
38
|
Abstract
Neurons have their own systems for regulating RNA. Several multigene families encode RNA binding proteins (RNABPs) that are uniquely expressed in neurons, including the well-known neuron-specific markers ELAV and NeuN and the disease antigen NOVA. New technologies have emerged in recent years to assess the function of these proteins in vivo, and the answers are yielding insights into how and why neurons may regulate RNA in special ways-to increase cellular complexity, to localize messenger RNA (mRNA) spatially, and to regulate their expression in response to synaptic stimuli. The functions of such restricted neuronal proteins are likely to be complemented by more widely expressed RNABPs that may themselves have developed specialized functions in neurons, including Argonaute/microRNAs (miRNAs). Here we review what is known about such RNABPs and explore the potential biologic and neurologic significance of neuronal RNA regulatory systems.
Collapse
Affiliation(s)
- Robert B Darnell
- Department of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
| |
Collapse
|
39
|
Weake VM, Dyer JO, Seidel C, Box A, Swanson SK, Peak A, Florens L, Washburn MP, Abmayr SM, Workman JL. Post-transcription initiation function of the ubiquitous SAGA complex in tissue-specific gene activation. Genes Dev 2011; 25:1499-509. [PMID: 21764853 DOI: 10.1101/gad.2046211] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The Spt-Ada-Gcn5-acetyltransferase (SAGA) complex was discovered from Saccharomyces cerevisiae and has been well characterized as an important transcriptional coactivator that interacts both with sequence-specific transcription factors and the TATA-binding protein TBP. SAGA contains a histone acetyltransferase and a ubiquitin protease. In metazoans, SAGA is essential for development, yet little is known about the function of SAGA in differentiating tissue. We analyzed the composition, interacting proteins, and genomic distribution of SAGA in muscle and neuronal tissue of late stage Drosophila melanogaster embryos. The subunit composition of SAGA was the same in each tissue; however, SAGA was associated with considerably more transcription factors in muscle compared with neurons. Consistent with this finding, SAGA was found to occupy more genes specifically in muscle than in neurons. Strikingly, SAGA occupancy was not limited to enhancers and promoters but primarily colocalized with RNA polymerase II within transcribed sequences. SAGA binding peaks at the site of RNA polymerase pausing at the 5' end of transcribed sequences. In addition, many tissue-specific SAGA-bound genes required its ubiquitin protease activity for full expression. These data indicate that in metazoans SAGA plays a prominent post-transcription initiation role in tissue-specific gene expression.
Collapse
Affiliation(s)
- Vikki M Weake
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Callan MA, Zarnescu DC. Heads-up: new roles for the fragile X mental retardation protein in neural stem and progenitor cells. Genesis 2011; 49:424-40. [PMID: 21404421 DOI: 10.1002/dvg.20745] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 02/23/2011] [Accepted: 02/27/2011] [Indexed: 11/12/2022]
Abstract
Fragile X syndrome (FXS) is the most common form of inherited mental retardation and is caused by the loss of function for Fragile X Mental Retardation Protein (FMRP), a selective RNA-binding protein with a demonstrated role in the localized translation of target mRNAs at synapses. Several recent studies provide compelling evidence for a new role of FMRP in the development of the nervous system, during neurogenesis. Using a multi-faceted approach and a variety of model systems ranging from cultured neurospheres and progenitor cells to in vivo Drosophila and mouse models these reports indicate that FMRP is required for neural stem and progenitor cell proliferation, differentiation, survival, as well as regulation of gene expression. Here we compare and contrast these recent reports and discuss the implications of FMRP's new role in embryonic and adult neurogenesis, including the development of novel therapeutic approaches to FXS and related neurological disorders such as autism.
Collapse
Affiliation(s)
- Matthew A Callan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, USA
| | | |
Collapse
|
41
|
Differential regulation of synchronous versus asynchronous neurotransmitter release by the C2 domains of synaptotagmin 1. Proc Natl Acad Sci U S A 2010; 107:14869-74. [PMID: 20679236 DOI: 10.1073/pnas.1000606107] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Synaptic vesicle fusion at many synapses has been kinetically separated into two distinct Ca(2+)-dependent temporal components consisting of a rapid synchronous phase followed by a slower asynchronous component. Mutations in the synaptic vesicle Ca(2+) sensor Synaptotagmin 1 (Syt 1) reduce synchronous neurotransmission while enhancing the slower asynchronous phase of release. Syt 1 regulation of vesicle fusion requires interactions mediated by its tandem cytoplasmic C2 domains (C2A and C2B). Although Ca(2+) binding by Syt 1 is predicted to drive synchronous release, it is unknown if Ca(2+) interactions with either C2 domain is required for suppression of asynchronous release. To determine if Ca(2+) binding by Syt 1 regulates these two phases of release independently, we performed electrophysiological analysis of transgenically expressed Syt 1 mutated at Ca(2+) binding sites in C2A or C2B in the background of Drosophila Syt 1-null mutants. Transgenic animals expressing mutations that disrupt Ca(2+) binding to C2A fully restored the synchronous phase of neurotransmitter release, whereas the asynchronous component was not suppressed. In contrast, rescue with Ca(2+)-binding mutants in C2B displayed little rescue of the synchronous release component, but reduced asynchronous release. These results suggest that the tandem C2 domains of Syt 1 play independent roles in neurotransmission, as Ca(2+) binding to C2A suppresses asynchronous release, whereas Ca(2+) binding to C2B mediates synchronous fusion.
Collapse
|
42
|
Toba G, Yamamoto D, White K. Life-span phenotypes of elav and Rbp9 in Drosophila suggest functional cooperation of the two ELAV-family protein genes. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2010; 74:261-265. [PMID: 20589912 DOI: 10.1002/arch.20377] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The ELAV family of RNA-binding proteins is involved in various aspects of the post-transcriptional regulation of gene expression, from alternative splicing to translation. The members of this family have been shown to interact with each other and have been suggested to function as homo- and/or hetero-multimers. However, the functional interactions among them have not been demonstrated in vivo. In this study, we examined the genetic interaction between elav and Rbp9, two of the three genes encoding ELAV-family proteins in Drosophila. Mutants of both elav and Rbp9 showed shorter life spans than the control, with elav showing a shorter life span than Rbp9. The survival curve of elav-Rbp9 double-mutant flies was indistinguishable from that of elav single-mutant flies, suggesting that both mutations affect longevity through the same pathway. Considering the fact that both genes are co-expressed in adult neurons, we hypothesize that ELAV and Rbp9 cooperate to maintain the functional integrity of the adult nervous system.
Collapse
Affiliation(s)
- Gakuta Toba
- Department of Biology and Volen National Center for Complex Systems, MS008, Brandeis University, Waltham, Massachusetts, USA
| | | | | |
Collapse
|
43
|
Walker WB, Smith EM, Jan T, Zwiebel L. A functional role for Anopheles gambiae Arrestin1 in olfactory signal transduction. JOURNAL OF INSECT PHYSIOLOGY 2008; 54:680-690. [PMID: 18328499 PMCID: PMC2408752 DOI: 10.1016/j.jinsphys.2008.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/22/2008] [Accepted: 01/23/2008] [Indexed: 05/26/2023]
Abstract
Insect sensory arrestins act to desensitize visual and olfactory signal transduction pathways, as evidenced by the phenotypic effects of mutations in the genes encoding both Arr1 and Arr2 in Drosophila melanogaster. To assess whether such arrestins play similar roles in other, more medically relevant dipterans, we examined the ability of Anopheles gambiae sensory arrestin homologs AgArr1 and AgArr2 to rescue phenotypes associated with an olfactory deficit observed in D. melanogaster arrestin mutants. Of these, only AgArr1 facilitated significant phenotypic rescue of the corresponding Drosophila arr mutant olfactory phenotype, consistent with the view that functional orthology is shared by these Arr1 homologs. These results represent the first step in the functional characterization of AgArr1, which is highly expressed in olfactory appendages of An. gambiae in which it is likely to play an essential role in olfactory signal transduction. In addition to providing insight into the common elements of the peripheral olfactory system of dipterans, this work validates the importance of AgArr1 as a potential target for novel anti-malaria strategies that focus on olfactory-based behaviors in An. gambiae.
Collapse
Affiliation(s)
- William B. Walker
- Department of Biological Sciences, Centers for Molecular Neuroscience and Global Health and Programs in Development, Genetics Vanderbilt University, Nashville, Tennessee, 37232
- Neuroscience Graduate Program, Vanderbilt University, Nashville, Tennessee 37232
| | - Elaine M. Smith
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
| | - Taha Jan
- Stanford University School of Medicine, Stanford, California, 94305
| | - L.J. Zwiebel
- Department of Biological Sciences, Centers for Molecular Neuroscience and Global Health and Programs in Development, Genetics Vanderbilt University, Nashville, Tennessee, 37232
- Neuroscience Graduate Program, Vanderbilt University, Nashville, Tennessee 37232
| |
Collapse
|
44
|
Long persistence of importin-β explains extended survival of cells and zygotes that lack the encoding gene. Mech Dev 2008; 125:196-206. [DOI: 10.1016/j.mod.2007.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Accepted: 12/05/2007] [Indexed: 11/23/2022]
|
45
|
Mondal K, Dastidar AG, Singh G, Madhusudhanan S, Gande SL, VijayRaghavan K, Varadarajan R. Design and isolation of temperature-sensitive mutants of Gal4 in yeast and Drosophila. J Mol Biol 2007; 370:939-50. [PMID: 17553522 DOI: 10.1016/j.jmb.2007.05.035] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2007] [Revised: 05/08/2007] [Accepted: 05/10/2007] [Indexed: 11/18/2022]
Abstract
Little is known about mechanisms responsible for the temperature-sensitive (ts) phenotype, or of the transferability of ts mutants of a specific gene between organisms. Using a structure-based approach, nine ts mutants of Gal4 were generated in yeast by mutating four DNA binding residues. Two of these nine yeast ts mutants were cloned into P element vectors under control of the Elav and GMR promoters and transgenic Drosophila lines were generated. These were crossed to UAS reporter lines and progeny were characterized for reporter gene expression as a function of temperature. Both of these yeast ts mutants show a ts phenotype in Drosophila and result in rapid induction of reporter gene expression upon shifting to the permissive temperature. Exposed, functional residues involved in protein-ligand or protein-protein interactions appear to be attractive candidate sites for generating ts mutants that are transferable between organisms.
Collapse
Affiliation(s)
- Kajari Mondal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | | | | | | | | | | | | |
Collapse
|
46
|
Chen HH, Xu J, Safarpour F, Stewart AFR. LMO4 mRNA stability is regulated by extracellular ATP in F11 cells. Biochem Biophys Res Commun 2007; 357:56-61. [PMID: 17418808 DOI: 10.1016/j.bbrc.2007.03.113] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2007] [Accepted: 03/12/2007] [Indexed: 10/23/2022]
Abstract
LIM only domain protein 4 (LMO4) interacts with many signaling and transcription factors to regulate cellular proliferation, differentiation and plasticity. In Drosophila, mutations in the 3' untranslated region (UTR) of the homologue dLMO cause a gain of function by increasing mRNA stability. LMO4 3'UTR contains several AU-rich elements (ARE) and is highly conserved among vertebrates, suggesting that RNA destabilizing mechanisms are evolutionarily conserved. Here, we found that extracellular ATP stabilized LMO4 mRNA in F11 cells. The LMO4 3'UTR added to a luciferase reporter markedly reduced reporter activity under basal conditions, but increased activity with ATP treatment. Two ARE motifs were characterized in the LMO4 3'UTR. ATP increased binding of HuD protein to ARE1. ARE1 conferred ATP and HuD-dependent mRNA stabilization. In contrast, sequences flanking ARE2 bound CUGBP1 and ATP destabilized this complex. Thus, our results suggest that ATP modulates recruitment of RNA-binding proteins to the 3'UTR to stabilize LMO4 mRNA.
Collapse
Affiliation(s)
- Hsiao-Huei Chen
- Ottawa Health Research Institute, Neuroscience, Centre for Stroke Recovery, 451 Smyth Road, Ottawa, Ont., Canada K1H 8M5.
| | | | | | | |
Collapse
|
47
|
Slevin MK, Gourronc F, Hartley RS. ElrA binding to the 3'UTR of cyclin E1 mRNA requires polyadenylation elements. Nucleic Acids Res 2007; 35:2167-76. [PMID: 17355986 PMCID: PMC1874641 DOI: 10.1093/nar/gkm084] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2006] [Revised: 01/29/2007] [Accepted: 01/30/2007] [Indexed: 01/02/2023] Open
Abstract
The early cell divisions of Xenopus laevis and other metazoan embryos occur in the presence of constitutively high levels of the cell cycle regulator cyclin E1. Upon completion of the 12th cell division, a time at which many maternal proteins are downregulated by deadenylation and destabilization of their encoding mRNAs, maternal cyclin E1 protein is downregulated while its mRNA is polyadenylated and stable. We report here that stable polyadenylation of cyclin E1 mRNA requires three cis-acting elements in the 3' untranslated region; the nuclear polyadenylation sequence, a contiguous cytoplasmic polyadenylation element and an upstream AU-rich element. ElrA, the Xenopus homolog of HuR and a member of the ELAV gene family binds the cyclin E1 3'UTR with high affinity. Deletion of these elements dramatically reduces the affinity of ElrA for the cyclin E1 3'UTR, abolishes polyadenylation and destabilizes the mRNA. Together, these findings provide compelling evidence that ElrA functions in polyadenylation and stabilization of cyclin E1 mRNA via binding these elements.
Collapse
Affiliation(s)
- Michael K. Slevin
- Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA 52242, USA Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Francoise Gourronc
- Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA 52242, USA Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Rebecca S. Hartley
- Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA 52242, USA Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM 87131, USA
| |
Collapse
|
48
|
Merrill CE, Sherertz TM, Walker WB, Zwiebel LJ. Odorant-specific requirements for arrestin function in Drosophila olfaction. ACTA ACUST UNITED AC 2005; 63:15-28. [PMID: 15627264 DOI: 10.1002/neu.20113] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability to modulate olfactory sensitivity is necessary to detect chemical gradients and discriminate among a multitude of odor stimuli. Desensitization of odorant receptors has been postulated to occur when arrestins prevent the activation of downstream second messengers. A paucity of in vivo data on olfactory desensitization prompts use of Drosophila melanogaster genetics to investigate arrestins' role in regulating olfactory signaling pathways. Physiological analysis of peripheral olfactory sensitivity reveals decreased responsiveness to a host of chemically distinct odorants in flies deficient for arrestin1 (arr1), arrestin2 (arr2), or both. These phenotypes are manifest in odorant- and dose- dependent fashions. Additionally, mutants display altered adaptive properties under a prolonged exposure paradigm. Behaviorally, arr1 mutants are impaired in olfactory-based orientation towards attractive odor sources. As the olfactory deficits vary according to chemical identity and concentration, they indicate that a spectrum of arrestin activity is essential for odor processing depending upon the particular olfactory pathway involved. Arrestin mutant phenotypes are hypothesized to be a consequence of down-regulation of olfactory signaling to avoid cellular excitotoxicity. Importantly, phenotypic rescue of olfactory defects in arr1(1) mutants is achieved through transgenic expression of wild-type arr1. Taken together, these data clearly indicate that arrestins are required in a stimulus-specific manner for wild type olfactory function and add another level of complexity to peripheral odor coding mechanisms that ultimately impact olfactory behavior.
Collapse
Affiliation(s)
- C Elaine Merrill
- Department of Biological Sciences, Vanderbilt University, 465 21st Avenue South, Nashville, Tennessee 37232, USA
| | | | | | | |
Collapse
|
49
|
Karandikar UC, Trott RL, Yin J, Bishop CP, Bidwai AP. Drosophila CK2 regulates eye morphogenesis via phosphorylation of E(spl)M8. Mech Dev 2004; 121:273-86. [PMID: 15003630 DOI: 10.1016/j.mod.2004.01.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2003] [Revised: 12/19/2003] [Accepted: 01/06/2004] [Indexed: 10/26/2022]
Abstract
The Notch effector E(spl)M8 is phosphorylated at Ser159 by CK2, a highly conserved Ser/Thr protein kinase. We have used the Gal4-UAS system to assess the role of M8 phosphorylation during bristle and eye morphogenesis by employing a non-phosphorylatable variant (M8SA) or one predicted to mimic the 'constitutively' phosphorylated protein (M8SD). We find that phosphorylation of M8 does not appear to be critical during bristle morphogenesis. In contrast, only M8SD elicits a severe 'reduced eye' phenotype when it is expressed in the morphogenetic furrow of the eye disc. M8SD elicits neural hypoplasia in eye discs, elicits loss of phase-shifted Atonal-positive cells, i.e. the 'founding' R8 photoreceptors, and consequently leads to apoptosis. The ommatidial phenotype of M8SD is similar to that in Nspl/Y; E(spl)D/+ flies. E(spl)D, an allele of m8, encodes a truncated protein known as M8*, which, unlike wild type M8, displays exacerbated antagonism of Atonal via direct protein-protein interactions. In line with this, we find that the M8SD-Atonal interaction appears indistinguishable from that of M8*-Atonal, whereas interaction of M8 or M8SA appears marginal, at best. These results raise the possibility that phosphorylation of M8 (at Ser159) might be required for its ability to mediate 'lateral inhibition' within proneural clusters in the developing retina. This is the first identification of a dominant allele encoding a phosphorylation-site variant of an E(spl) protein. Our studies uncover a novel functional domain that is conserved amongst a subset of E(spl)/Hes repressors in Drosophila and mammals, and suggests a potential role for CK2 during retinal patterning.
Collapse
Affiliation(s)
- Umesh C Karandikar
- Department of Biology, Life Sciences Building, P.O. Box 6057, West Virginia University, Morgantown, WV 26506, USA
| | | | | | | | | |
Collapse
|
50
|
Paquet-Durand F, Bicker G. Hypoxic/ischaemic cell damage in cultured human NT-2 neurons. Brain Res 2004; 1011:33-47. [PMID: 15140642 DOI: 10.1016/j.brainres.2004.02.060] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2004] [Indexed: 10/26/2022]
Abstract
Postmitotic neurons were generated from the human NT-2 teratocarcinoma cell line in a novel rapid differentiation procedure. These neurons were used to establish an in vitro assay system that allows the investigation of hypoxic/ischaemic cell damage and the development of neuroprotective strategies. In experiments of simulated ischaemia, the neurons were subjected to anoxia and hypoglycaemia. The viability of NT-2 neuronal cells was significantly reduced by anoxia especially in the presence of glutamate, reflecting the cellular vulnerability to excitotoxic conditions. The addition of the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 reduced glutamate-induced neuronal damage. Calcium imaging showed that NT-2 neurons increased cytosolic calcium levels in response to stimulation with glutamate or NMDA, an effect that was abolished in calcium free medium and at low pH values. The NMDA receptor antagonists MK-801, AP 5 and ketamine reduced the NMDA-induced response, suggesting the presence of functional NMDA receptors in the human neuronal cells. The mitochondrial potential of neurons was estimated using the fluorescent dye rhodamine 123 (R123). The fluorescence imaging experiments indicated an energetic collapse of mitochondrial functions during anoxia, suggesting that the human NT-2 neurons can be used to investigate subcellular processes during the excitotoxic cascade.
Collapse
Affiliation(s)
- François Paquet-Durand
- School of Veterinary Medicine Hannover, Cell Biology, Bischofsholer Damm 15/102, D-30173 Hannover, Germany
| | | |
Collapse
|