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González YR, Kamkar F, Jafar-Nejad P, Wang S, Qu D, Alvarez LS, Hawari D, Sonnenfeld M, Slack RS, Albert PR, Park DS, Joselin A. PFTK1 kinase regulates axogenesis during development via RhoA activation. BMC Biol 2023; 21:240. [PMID: 37907898 PMCID: PMC10617079 DOI: 10.1186/s12915-023-01732-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 10/11/2023] [Indexed: 11/02/2023] Open
Abstract
BACKGROUND PFTK1/Eip63E is a member of the cyclin-dependent kinases (CDKs) family and plays an important role in normal cell cycle progression. Eip63E expresses primarily in postnatal and adult nervous system in Drosophila melanogaster but its role in CNS development remains unknown. We sought to understand the function of Eip63E in the CNS by studying the fly ventral nerve cord during development. RESULTS Our results demonstrate that Eip63E regulates axogenesis in neurons and its deficiency leads to neuronal defects. Functional interaction studies performed using the same system identify an interaction between Eip63E and the small GTPase Rho1. Furthermore, deficiency of Eip63E homolog in mice, PFTK1, in a newly generated PFTK1 knockout mice results in increased axonal outgrowth confirming that the developmental defects observed in the fly model are due to defects in axogenesis. Importantly, RhoA phosphorylation and activity are affected by PFTK1 in primary neuronal cultures. We report that GDP-bound inactive RhoA is a substrate of PFTK1 and PFTK1 phosphorylation is required for RhoA activity. CONCLUSIONS In conclusion, our work establishes an unreported neuronal role of PFTK1 in axon development mediated by phosphorylation and activation of GDP-bound RhoA. The results presented add to our understanding of the role of Cdks in the maintenance of RhoA-mediated axon growth and its impact on CNS development and axonal regeneration.
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Affiliation(s)
| | - Fatemeh Kamkar
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Paymaan Jafar-Nejad
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
- Present Address: Ionis Pharmaceuticals Inc., Carlsbad, CA, 92010, USA
| | - Suzi Wang
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Dianbo Qu
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Leticia Sanchez Alvarez
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Dina Hawari
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Margaret Sonnenfeld
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Ruth S Slack
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Paul R Albert
- Ottawa Hospital Research Institute and Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - David S Park
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada.
| | - Alvin Joselin
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada.
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2
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Zhang X, Wu X, Peng J, Sun A, Guo Y, Fu P, Gao G. Cis- and trans-regulation by histone H4 basic patch R17/R19 in metazoan development. Open Biol 2022; 12:220066. [PMID: 36382370 PMCID: PMC9667139 DOI: 10.1098/rsob.220066] [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: 06/23/2022] [Accepted: 10/25/2022] [Indexed: 11/18/2022] Open
Abstract
The histone H4 basic patch is critical for chromatin structure and regulation of the chromatin machinery. However, the biological roles of these positively charged residues and the mechanisms by which they regulate gene expression remain unclear. In this study, we used histone mutagenesis to investigate the physiological function and downstream regulatory genes of H4 residues R17 and R19 in Drosophila. We found all histone mutations including R17A/E/H and R19A/E/H (R17 and R19 of H4 are substituted by A, E and H respectively) result in a range of growth defects and abnormalities in chromosomal high-order structures, whereas R17E mutation is embryonic lethal. RNA-seq demonstrates that downregulated genes in both R17A and R19A show significant overlap and are enriched in development-related pathways. In addition, Western and cytological analyses showed that the R17A mutation resulted in a significant reduction in H4K16 acetylation and male offspring, implying that the R17 may be involved in male dosage compensation mechanisms. R19 mutation on the other hand strongly affect Gpp (Dot1 homologue in flies)-mediated H3K79 methylation, possibly through histone crosstalk. Together these results provide insights into the differential impacts of positive charges of H4 basic patch R17/R19 on regulation of gene transcription during developmental processes.
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Affiliation(s)
- Xuedi Zhang
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, People's Republic of China
| | - Xiangyu Wu
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, People's Republic of China
| | - Ju Peng
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, People's Republic of China
| | - Angyang Sun
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, People's Republic of China
| | - Yan Guo
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, People's Republic of China
| | - Pengchong Fu
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, People's Republic of China
| | - Guanjun Gao
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, People's Republic of China
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3
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DeAngelis MW, Coolon JD, Johnson RI. Comparative transcriptome analyses of the Drosophila pupal eye. G3-GENES GENOMES GENETICS 2021; 11:5995320. [PMID: 33561221 PMCID: PMC8043229 DOI: 10.1093/g3journal/jkaa003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/08/2020] [Indexed: 12/04/2022]
Abstract
Tissue function is dependent on correct cellular organization and behavior. As a result, the identification and study of genes that contribute to tissue morphogenesis is of paramount importance to the fields of cell and developmental biology. Many of the genes required for tissue patterning and organization are highly conserved between phyla. This has led to the emergence of several model organisms and developmental systems that are used to study tissue morphogenesis. One such model is the Drosophila melanogaster pupal eye that has a highly stereotyped arrangement of cells. In addition, the pupal eye is postmitotic that allows for the study of tissue morphogenesis independent from any effects of proliferation. While the changes in cell morphology and organization that occur throughout pupal eye development are well documented, less is known about the corresponding transcriptional changes that choreograph these processes. To identify these transcriptional changes, we dissected wild-type Canton S pupal eyes and performed RNA-sequencing. Our analyses identified differential expression of many loci that are documented regulators of pupal eye morphogenesis and contribute to multiple biological processes including signaling, axon projection, adhesion, and cell survival. We also identified differential expression of genes not previously implicated in pupal eye morphogenesis such as components of the Toll pathway, several non-classical cadherins, and components of the muscle sarcomere, which could suggest these loci function as novel patterning factors.
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Affiliation(s)
- Miles W DeAngelis
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Joseph D Coolon
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Ruth I Johnson
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
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4
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Rasmussen ML, Ortolano NA, Romero-Morales AI, Gama V. Wnt Signaling and Its Impact on Mitochondrial and Cell Cycle Dynamics in Pluripotent Stem Cells. Genes (Basel) 2018; 9:genes9020109. [PMID: 29463061 PMCID: PMC5852605 DOI: 10.3390/genes9020109] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/13/2018] [Accepted: 02/14/2018] [Indexed: 12/17/2022] Open
Abstract
The core transcriptional network regulating stem cell self-renewal and pluripotency remains an intense area of research. Increasing evidence indicates that modified regulation of basic cellular processes such as mitochondrial dynamics, apoptosis, and cell cycle are also essential for pluripotent stem cell identity and fate decisions. Here, we review evidence for Wnt regulation of pluripotency and self-renewal, and its connections to emerging features of pluripotent stem cells, including (1) increased mitochondrial fragmentation, (2) increased sensitivity to cell death, and (3) shortened cell cycle. We provide a general overview of the stem cell–specific mechanisms involved in the maintenance of these uncharacterized hallmarks of pluripotency and highlight potential links to the Wnt signaling pathway. Given the physiological importance of stem cells and their enormous potential for regenerative medicine, understanding fundamental mechanisms mediating the crosstalk between Wnt, organelle-dynamics, apoptosis, and cell cycle will be crucial to gain insight into the regulation of stemness.
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Affiliation(s)
- Megan L Rasmussen
- Department of Cell and Developmental Biology; Vanderbilt University, Nashville, TN37232, United States.
| | - Natalya A Ortolano
- Department of Cell and Developmental Biology; Vanderbilt University, Nashville, TN37232, United States.
| | | | - Vivian Gama
- Department of Cell and Developmental Biology; Vanderbilt University, Nashville, TN37232, United States.
- Vanderbilt Center for Stem Cell Biology; Vanderbilt University, Nashville, TN37232, United States.
- Vanderbilt Ingram Cancer Center; Vanderbilt University, Nashville, TN37232, United States.
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5
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Wang X, Jia Y, Fei C, Song X, Li L. Activation/Proliferation-associated Protein 2 (Caprin-2) Positively Regulates CDK14/Cyclin Y-mediated Lipoprotein Receptor-related Protein 5 and 6 (LRP5/6) Constitutive Phosphorylation. J Biol Chem 2016; 291:26427-26434. [PMID: 27821587 DOI: 10.1074/jbc.m116.744607] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 11/03/2016] [Indexed: 01/13/2023] Open
Abstract
Low-density lipoprotein receptor-related proteins 5 and 6 (LRP5/6) are co-receptors for Wnt ligands. Upon ligand binding, LRP5/6 undergo glycogen synthase kinase 3 (GSK3)/casein kinase I (CKI)-mediated phosphorylation at multiple PPP(S/T)P motifs in the intracellular domain, which is essential for canonical Wnt signal transduction. On the other hand, in the Wnt-off state, the mitosis-specific CDK14-Cyclin Y kinase complex phosphorylates Ser-1490 of LRP5/6 at G2/M, thereby priming the receptor for Wnt-induced phosphorylation. However, it remains unclear how CDK14/Cyclin Y is recruited to LRP5/6 and whether there are other cofactors involved in this process. Previously, we identified Caprin-2 as a positive regulator of canonical Wnt signaling by promoting GSK3-depedent LRP5/6 phosphorylation upon Wnt stimulation. Here we uncovered that Caprin-2 positively regulates constitutive LRP5/6 Ser-1490 phosphorylation by complexing with CDK14/Cyclin Y. Caprin-2-mediated LRP5/6 phosphorylation is cell cycle-dependent in a pattern similar to that of CDK14/Cyclin Y-dependent LRP5/6 phosphorylation. Moreover, knockdown of Caprin-2 disrupts not only the interaction between CDK14 and Cyclin Y but also the interaction between CDK14/Cyclin Y and LRP6. Overall, our findings revealed an unrecognized role of Caprin-2 in facilitating LRP5/6 constitutive phosphorylation at G2/M through forming a quaternary complex with CDK14, Cyclin Y, and LRP5/6.
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Affiliation(s)
- Xin Wang
- From the State Key Laboratory of Molecular Biology, Chinese Academy of Sciences Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yingying Jia
- From the State Key Laboratory of Molecular Biology, Chinese Academy of Sciences Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Cong Fei
- From the State Key Laboratory of Molecular Biology, Chinese Academy of Sciences Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiaomin Song
- From the State Key Laboratory of Molecular Biology, Chinese Academy of Sciences Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Lin Li
- From the State Key Laboratory of Molecular Biology, Chinese Academy of Sciences Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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6
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Jukam D, Viets K, Anderson C, Zhou C, DeFord P, Yan J, Cao J, Johnston RJ. The insulator protein BEAF-32 is required for Hippo pathway activity in the terminal differentiation of neuronal subtypes. Development 2016; 143:2389-97. [PMID: 27226322 DOI: 10.1242/dev.134700] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 05/11/2016] [Indexed: 01/07/2023]
Abstract
The Hippo pathway is crucial for not only normal growth and apoptosis but also cell fate specification during development. What controls Hippo pathway activity during cell fate specification is incompletely understood. In this article, we identify the insulator protein BEAF-32 as a regulator of Hippo pathway activity in Drosophila photoreceptor differentiation. Though morphologically uniform, the fly eye is composed of two subtypes of R8 photoreceptor neurons defined by expression of light-detecting Rhodopsin proteins. In one R8 subtype, active Hippo signaling induces Rhodopsin 6 (Rh6) and represses Rhodopsin 5 (Rh5), whereas in the other subtype, inactive Hippo signaling induces Rh5 and represses Rh6. The activity state of the Hippo pathway in R8 cells is determined by the expression of warts, a core pathway kinase, which interacts with the growth regulator melted in a double-negative feedback loop. We show that BEAF-32 is required for expression of warts and repression of melted Furthermore, BEAF-32 plays a second role downstream of Warts to induce Rh6 and prevent Rh5 fate. BEAF-32 is dispensable for Warts feedback, indicating that BEAF-32 differentially regulates warts and Rhodopsins. Loss of BEAF-32 does not noticeably impair the functions of the Hippo pathway in eye growth regulation. Our study identifies a context-specific regulator of Hippo pathway activity in post-mitotic neuronal fate, and reveals a developmentally specific role for a broadly expressed insulator protein.
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Affiliation(s)
- David Jukam
- Center for Developmental Genetics, Department of Biology, New York University, 100 Washington Square East, New York, NY 10003-6688, USA
| | - Kayla Viets
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2685, USA
| | - Caitlin Anderson
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2685, USA
| | - Cyrus Zhou
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2685, USA
| | - Peter DeFord
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2685, USA
| | - Jenny Yan
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2685, USA
| | - Jinshuai Cao
- Center for Developmental Genetics, Department of Biology, New York University, 100 Washington Square East, New York, NY 10003-6688, USA
| | - Robert J Johnston
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218-2685, USA
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7
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Foulk MS, Waggener JM, Johnson JM, Yamamoto Y, Liew GM, Urnov FD, Young Y, Lee G, Smith HS, Gerbi SA. Isolation and characterization of the ecdysone receptor and its heterodimeric partner ultraspiracle through development in Sciara coprophila. Chromosoma 2013; 122:103-19. [PMID: 23321980 DOI: 10.1007/s00412-012-0395-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 12/09/2012] [Accepted: 12/18/2012] [Indexed: 01/08/2023]
Abstract
Regulation of DNA replication is critical, and loss of control can lead to DNA amplification. Naturally occurring, developmentally regulated DNA amplification occurs in the DNA puffs of the late larval salivary gland giant polytene chromosomes in the fungus fly, Sciara coprophila. The steroid hormone ecdysone induces DNA amplification in Sciara, and the amplification origin of DNA puff II/9A contains a putative binding site for the ecdysone receptor (EcR). We report here the isolation, cloning, and characterizing of two ecdysone receptor isoforms in Sciara (ScEcR-A and ScEcR-B) and the heterodimeric partner, ultraspiracle (ScUSP). ScEcR-A is the predominant isoform in larval tissues and ScEcR-B in adult tissues, contrary to the pattern in Drosophila. Moreover, ScEcR-A is produced at amplification but is absent just prior. We discuss these results in relation to the model of ecdysone regulation of DNA amplification.
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Affiliation(s)
- Michael S Foulk
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, 02912, USA
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8
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Mikolcevic P, Rainer J, Geley S. Orphan kinases turn eccentric: a new class of cyclin Y-activated, membrane-targeted CDKs. Cell Cycle 2012; 11:3758-68. [PMID: 22895054 DOI: 10.4161/cc.21592] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PCTAIRE kinases (PCTK) are a highly conserved, but poorly characterized, subgroup of cyclin-dependent kinases (CDK). They are characterized by a conserved catalytic domain flanked by N- and C-terminal extensions that are involved in cyclin binding. Vertebrate genomes contain three highly similar PCTAIRE kinases (PCTK1,2,3, a.k.a., CDK16,17,18), which are most abundant in post-mitotic cells in brain and testis. Consistent with this restricted expression pattern, PCTK1 (CDK16) has recently been shown to be essential for spermatogenesis. PCTAIREs are activated by cyclin Y (CCNY), a highly conserved single cyclin fold protein. By binding to N-myristoylated CCNY, CDK16 is targeted to the plasma membrane. Unlike conventional cyclin-CDK interactions, binding of CCNY to CDK16 not only requires the catalytic domain, but also domains within the N-terminal extension. Interestingly, phosphorylation within this domain blocks CCNY binding, providing a novel means of cyclin-CDK regulation. By using these functional characteristics, we analyzed "PCTAIRE" sequence containing protein kinase genes in genomes of various organisms and found that CCNY and CCNY-dependent kinases are restricted to eumetazoa and possibly evolved along with development of a central nervous system. Here, we focus on the structure and regulation of PCTAIREs and discuss their established functions.
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Affiliation(s)
- Petra Mikolcevic
- Division of Molecular Pathophysiology, Biocenter, Innsbruck Medical University, Innsbruck, Austria
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9
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Cyclin-dependent kinase 16/PCTAIRE kinase 1 is activated by cyclin Y and is essential for spermatogenesis. Mol Cell Biol 2011; 32:868-79. [PMID: 22184064 DOI: 10.1128/mcb.06261-11] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cyclin-dependent kinase 16 (CDK16, PCTK1) is a poorly characterized protein kinase, highly expressed in the testis and the brain. Here, we report that CDK16 is activated by membrane-associated cyclin Y (CCNY). Treatment of transfected human cells with the protein kinase A (PKA) activator forskolin blocked, while kinase inhibition promoted, CCNY-dependent targeting of CDK16-green fluorescent protein (GFP) to the cell membrane. CCNY binding to CDK16 required a region upstream of the kinase domain and was found to be inhibited by phosphorylation of serine 153, a potential PKA phosphorylation site. Thus, in contrast to other CDKs, CDK16 is regulated by phosphorylation-controlled cyclin binding. CDK16 isolated from murine testis was unphosphorylated, interacted with CCNY, and exhibited kinase activity. To investigate the function of CDK16 in vivo, we established a conditional knockout allele. Mice lacking CDK16 developed normally, but male mice were infertile. Spermatozoa isolated from their epididymis displayed thinning and elongation of the annulus region, adopted a bent shape, and showed impaired motility. Moreover, CDK16-deficient spermatozoa had malformed heads and excess residual cytoplasm, suggesting a role of CDK16 in spermiation. Thus, CDK16 is a membrane-targeted CDK essential for spermatogenesis.
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10
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Turner TL, Stewart AD, Fields AT, Rice WR, Tarone AM. Population-based resequencing of experimentally evolved populations reveals the genetic basis of body size variation in Drosophila melanogaster. PLoS Genet 2011; 7:e1001336. [PMID: 21437274 PMCID: PMC3060078 DOI: 10.1371/journal.pgen.1001336] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 02/14/2011] [Indexed: 01/08/2023] Open
Abstract
Body size is a classic quantitative trait with evolutionarily significant variation within many species. Locating the alleles responsible for this variation would help understand the maintenance of variation in body size in particular, as well as quantitative traits in general. However, successful genome-wide association of genotype and phenotype may require very large sample sizes if alleles have low population frequencies or modest effects. As a complementary approach, we propose that population-based resequencing of experimentally evolved populations allows for considerable power to map functional variation. Here, we use this technique to investigate the genetic basis of natural variation in body size in Drosophila melanogaster. Significant differentiation of hundreds of loci in replicate selection populations supports the hypothesis that the genetic basis of body size variation is very polygenic in D. melanogaster. Significantly differentiated variants are limited to single genes at some loci, allowing precise hypotheses to be formed regarding causal polymorphisms, while other significant regions are large and contain many genes. By using significantly associated polymorphisms as a priori candidates in follow-up studies, these data are expected to provide considerable power to determine the genetic basis of natural variation in body size. Understanding the causes and consequences of natural genetic variation is crucial to the characterization of biological evolution. Moreover, natural genetic variation is comprised of millions of perturbations, which are partially randomized across genotypes such that a small number of individuals can be used to combinatorially analyze a large number of differences, facilitating mechanistic understanding of biological systems. Here we demonstrate a powerful technique to parse genomic variation using artificial selection. By selecting replicate populations of Drosophila flies to become bigger and smaller, and then determining the evolutionary response at the genomic level, we have mapped hundreds of genes that respond to selection on body size. As our approach is powerful and cost-effective compared to existing approaches, we expect it to be a major component of diverse future efforts.
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Affiliation(s)
- Thomas L Turner
- Ecology, Evolution, and Marine Biology Department, University of California Santa Barbara, Santa Barbara, California, USA.
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11
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Yao Q, Zhang D, Tang B, Chen J, Chen J, Lu L, Zhang W. Identification of 20-hydroxyecdysone late-response genes in the chitin biosynthesis pathway. PLoS One 2010; 5:e14058. [PMID: 21124981 PMCID: PMC2987807 DOI: 10.1371/journal.pone.0014058] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 10/28/2010] [Indexed: 12/04/2022] Open
Abstract
Background 20-hydroxyecdysone (20E) and its receptor complex ecdysone receptor (EcR) and ultraspiracle (USP) play a crucial role in controlling development, metamorphosis, reproduction and diapause. The ligand-receptor complex 20E-EcR/USP directly activates a small set of early-response genes and a much larger set of late-response genes. However, ecdysone-responsive genes have not been previously characterized in the context of insect chitin biosynthesis. Principal Findings Here, we show that injection-based RNA interference (RNAi) directed towards a common region of the two isoforms of SeEcR in a lepidopteron insect Spodoptera exigua was effective, with phenotypes including a high mortality prior to pupation and developmental defects. After gene specific RNAi, chitin contents in the cuticle of an abnormal larva significantly decreased. The expression levels of five genes in the chitin biosynthesis pathway, SeTre-1, SeG6PI, SeUAP, SeCHSA and SeCHSB, were significantly reduced, while there was no difference in the expression of SeTre-2 prior to 72 hr after injection of EcR dsRNA. Meanwhile, injection of 20E in vivo induced the expression of the five genes mentioned above. Moreover, the SeTre-1, SeG6PI, SeUAP and SeCHSB genes showed late responses to the hormone and the induction of SeTre-1, SeG6PI, SeUAP and SeCHSB genes by 20E were able to be inhibited by the protein synthesis inhibitor cycloheximide in vitro indicating these genes are 20E late-response genes. Conclusions We conclude that SeTre-1, SeG6PI, SeUAP and SeCHSB in the chitin biosynthesis pathway are 20E late-response genes and 20E and its specific receptors plays a key role in the regulation of chitin biosynthesis via inducing their expression.
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Affiliation(s)
- Qiong Yao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Daowei Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Bin Tang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- Hangzhou Key Laboratory of Animal Adaptation and Evolution, Hangzhou Normal University, Hangzhou, China
| | - Jie Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jing Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Liang Lu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wenqing Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- * E-mail:
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12
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Liu D, Guest S, Finley RL. Why cyclin Y? A highly conserved cyclin with essential functions. Fly (Austin) 2010; 4:278-82. [PMID: 20699655 DOI: 10.4161/fly.4.4.12881] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cyclin Y is one of the most highly conserved members of the cyclin superfamily of proteins, which are famous for their crucial roles in regulating the cell cycle and transcription. Despite this high degree of conservation, very little was known about Cyclin Y function prior to a handful of studies published in this past year. Cyclins typically function by activating cyclin-dependent kinases (Cdks) and one insight has come from the identification of a Cdk that is activated by Cyclin Y. Yeast two-hybrid data first linked Cyclin Y with Cdk14, known as Eip63E in Drosophila or PFTAIRE1 in vertebrates. In Drosophila, both Cyclin Y and Eip63E are essential at many stages of development, from embryogenesis to metamorphosis and null mutants show a similar spectrum of developmental defects. In cultured cells, Cyclin Y and Eip63E were shown to phosphorylate the Wg/Wnt co-receptor Arrow/LRP6 in a ligand-independent manner. Eip63E is recruited to LRP6 at the plasma membrane by interacting with Cyclin Y, which is tethered to the membrane through an N-terminal myristoylation. Cyclin Y-dependent LRP6 phosphorylation appears to prime the receptor for subsequent ligand-dependent phosphorylation and activation of the canonical Wnt signaling pathway. Interestingly, Wnt receptor phosphorylation and signaling is maximal in G₂/M when Cyclin Y is at its highest levels, suggesting that Cyclin Y may serve to entrain Wnt signaling to the cell cycle. Given the wide range of roles for Wnt signaling during development, these studies may help explain why Cyclin Y is required at several developmental stages and in turn why these proteins are so well conserved in metazoans.
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Affiliation(s)
- Dongmei Liu
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA
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Niehrs C, Shen J. Regulation of Lrp6 phosphorylation. Cell Mol Life Sci 2010; 67:2551-62. [PMID: 20229235 PMCID: PMC11115861 DOI: 10.1007/s00018-010-0329-3] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 02/08/2010] [Accepted: 02/19/2010] [Indexed: 12/14/2022]
Abstract
The Wnt/beta-catenin signaling pathway plays important roles in embryonic development and tissue homeostasis, and is implicated in human disease. Wnts transduce signals via transmembrane receptors of the Frizzled (Fzd/Fz) family and the low density lipoprotein receptor-related protein 5/6 (Lrp5/6). A key mechanism in their signal transduction is that Wnts induce Lrp6 signalosomes, which become phosphorylated at multiple conserved sites, notably at PPSPXS motifs. Lrp6 phosphorylation is crucial to beta-catenin stabilization and pathway activation by promoting Axin and Gsk3 recruitment to phosphorylated sites. Here, we summarize how proline-directed kinases (Gsk3, PKA, Pftk1, Grk5/6) and non-proline-directed kinases (CK1 family) act upon Lrp6, how the phosphorylation is regulated by ligand binding and mitosis, and how Lrp6 phosphorylation leads to beta-catenin stabilization.
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Affiliation(s)
- Christof Niehrs
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 581, Heidelberg, Germany.
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14
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Davidson G, Niehrs C. Emerging links between CDK cell cycle regulators and Wnt signaling. Trends Cell Biol 2010; 20:453-60. [PMID: 20627573 DOI: 10.1016/j.tcb.2010.05.002] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 05/03/2010] [Accepted: 05/04/2010] [Indexed: 01/09/2023]
Abstract
Wnt/beta-catenin signaling controls many aspects of cell behavior throughout development and in adults. One of its best-known and cancer-relevant functions is to stimulate cell proliferation. Recent work has implicated Wnt components in regulating mitotic events, suggesting that the cell cycle and Wnt signaling are directly linked. This concept has now been substantially strengthened with the finding that the mitotic CDK14/cyclin Y complex promotes Wnt signaling through phosphorylation of the LRP6 co-receptor, a key regulatory nexus in the Wnt/beta-catenin pathway. Thus, an unexpectedly tight collaboration between the mitotic cell cycle machinery and Wnt signaling is emerging, suggesting that this pathway might orchestrate mitotic processes.
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Affiliation(s)
- Gary Davidson
- Karlsruhe Institute of Technology (KIT), Institute of Toxicology and Genetics, H. v. Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
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15
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Davidson G, Shen J, Huang YL, Su Y, Karaulanov E, Bartscherer K, Hassler C, Stannek P, Boutros M, Niehrs C. Cell cycle control of wnt receptor activation. Dev Cell 2010; 17:788-99. [PMID: 20059949 DOI: 10.1016/j.devcel.2009.11.006] [Citation(s) in RCA: 204] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 11/02/2009] [Accepted: 11/23/2009] [Indexed: 10/20/2022]
Abstract
Low-density lipoprotein receptor related proteins 5 and 6 (LRP5/6) are transmembrane receptors that initiate Wnt/beta-catenin signaling. Phosphorylation of PPPSP motifs in the LRP6 cytoplasmic domain is crucial for signal transduction. Using a kinome-wide RNAi screen, we show that PPPSP phosphorylation requires the Drosophila Cyclin-dependent kinase (CDK) L63. L63 and its vertebrate homolog PFTK are regulated by the membrane tethered G2/M Cyclin, Cyclin Y, which mediates binding to and phosphorylation of LRP6. As a consequence, LRP6 phosphorylation and Wnt/beta-catenin signaling are under cell cycle control and peak at G2/M phase; knockdown of the mitotic regulator CDC25/string, which results in G2/M arrest, enhances Wnt signaling in a Cyclin Y-dependent manner. In Xenopus embryos, Cyclin Y is required in vivo for LRP6 phosphorylation, maternal Wnt signaling, and Wnt-dependent anteroposterior embryonic patterning. G2/M priming of LRP6 by a Cyclin/CDK complex introduces an unexpected new layer of regulation of Wnt signaling.
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Affiliation(s)
- Gary Davidson
- Division of Molecular Embryology, Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, Hermann von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
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16
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Abstract
The Drosophila gene CG14939 encodes a member of a highly conserved family of cyclins, the Y-type cyclins, which have not been functionally characterized in any organism. Here we report the generation and phenotypic characterization of a null mutant of CG14939, which we rename Cyclin Y (CycY). We show that the null mutant, CycY(E8), is homozygous lethal with most mutant animals arresting during pupal development. The mutant exhibits delayed larval growth and major developmental defects during metamorphosis, including impaired gas bubble translocation, head eversion, leg elongation, and adult tissue growth. Heat-shock-induced expression of CycY at different times during development resulted in variable levels of rescue, the timing of which suggests a key function for zygotic CycY during the transition from third instar larvae to prepupae. CycY also plays an essential role during embryogenesis since zygotic null embryos from null mothers fail to hatch into first instar larvae. We provide evidence that the CycY protein (CycY) interacts with Eip63E, a cyclin-dependent kinase (Cdk) for which no cyclin partner had previously been identified. Like CycY, the Eip63E gene has essential functions during embryogenesis, larval development, and metamorphosis. Our data suggest that CycY/Eip63E form a cyclin/Cdk complex that is essential for several developmental processes.
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17
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Shu F, Lv S, Qin Y, Ma X, Wang X, Peng X, Luo Y, Xu BE, Sun X, Wu J. Functional characterization of human PFTK1 as a cyclin-dependent kinase. Proc Natl Acad Sci U S A 2007; 104:9248-53. [PMID: 17517622 PMCID: PMC1890480 DOI: 10.1073/pnas.0703327104] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Cyclin-dependent kinases (CDKs) are crucial regulators of the eukaryotic cell cycle whose activities are controlled by associated cyclins. PFTK1 shares limited homology to CDKs, but its ability to associate with any cyclins and its biological functions remain largely unknown. Here, we report the functional characterization of human PFTK1 as a CDK. PFTK1 specifically interacted with cyclin D3 (CCND3) and formed a ternary complex with the cell cycle inhibitor p21(Cip1) in mammalian cells. We demonstrated that the kinase activity of PFTK1 depended on CCND3 and was negatively regulated by p21(Cip1). Moreover, we identified the tumor suppressor Rb as a potential downstream substrate for the PFTK1/CCND3 complex. Importantly, knocking down PFTK1 expression by using siRNA caused cell cycle arrest at G(1), whereas ectopic expression of PFTK1 promoted cell proliferation. Taken together, our data strongly suggest that PFTK1 acts as a CDK that regulates cell cycle progression and cell proliferation.
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Affiliation(s)
| | | | | | | | - Xin Wang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, National Human Genome Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China; and
| | - Xiaozhong Peng
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, National Human Genome Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China; and
| | - Ying Luo
- *Shanghai Genomics, Inc
- Chinese National Human Genome Center, Shanghai, Zhangjiang Hi-Tech Park, Shanghai 201203, China
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, National Human Genome Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China; and
- GNI, Ltd., 4-2-12 Toranomon, Tokyo 1050001, Japan
| | | | - Xiaoqing Sun
- *Shanghai Genomics, Inc
- Chinese National Human Genome Center, Shanghai, Zhangjiang Hi-Tech Park, Shanghai 201203, China
| | - Jun Wu
- *Shanghai Genomics, Inc
- Chinese National Human Genome Center, Shanghai, Zhangjiang Hi-Tech Park, Shanghai 201203, China
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, National Human Genome Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China; and
- GNI, Ltd., 4-2-12 Toranomon, Tokyo 1050001, Japan
- To whom correspondence should be addressed. E-mail:
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18
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Hueber SD, Bezdan D, Henz SR, Blank M, Wu H, Lohmann I. Comparative analysis of Hox downstream genes in Drosophila. Development 2006; 134:381-92. [PMID: 17166915 DOI: 10.1242/dev.02746] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Functional diversification of body parts is dependent on the formation of specialized structures along the various body axes. In animals, region-specific morphogenesis along the anteroposterior axis is controlled by a group of conserved transcription factors encoded by the Hox genes. Although it has long been assumed that Hox proteins carry out their function by regulating distinct sets of downstream genes, only a small number of such genes have been found, with very few having direct roles in controlling cellular behavior. We have quantitatively identified hundreds of Hox downstream genes in Drosophila by microarray analysis, and validated many of them by in situ hybridizations on loss- and gain-of-function mutants. One important finding is that Hox proteins, despite their similar DNA-binding properties in vitro, have highly specific effects on the transcriptome in vivo, because expression of many downstream genes respond primarily to a single Hox protein. In addition, a large fraction of downstream genes encodes realizator functions, which directly affect morphogenetic processes, such as orientation and rate of cell divisions, cell-cell adhesion and communication, cell shape and migration, or cell death. Focusing on these realizators, we provide a framework for the morphogenesis of the maxillary segment. As the genomic organization of Hox genes and the interaction of Hox proteins with specific co-factors are conserved in vertebrates and invertebrates, and similar classes of downstream genes are regulated by Hox proteins across the metazoan phylogeny, our findings represent a first step toward a mechanistic understanding of morphological diversification within a species as well as between species.
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Affiliation(s)
- Stefanie D Hueber
- Max Planck Institute for Developmental Biology, Spemanstrasse 37-39, D-72076 Tübingen, Germany
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19
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Godfrey AC, Kupsco JM, Burch BD, Zimmerman RM, Dominski Z, Marzluff WF, Duronio RJ. U7 snRNA mutations in Drosophila block histone pre-mRNA processing and disrupt oogenesis. RNA (NEW YORK, N.Y.) 2006; 12:396-409. [PMID: 16495235 PMCID: PMC1383579 DOI: 10.1261/rna.2270406] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Metazoan replication-dependent histone mRNAs are not polyadenylated, and instead terminate in a conserved stem-loop structure generated by an endonucleolytic cleavage involving the U7 snRNP, which interacts with histone pre-mRNAs through base-pairing between U7 snRNA and a purine-rich sequence in the pre-mRNA located downstream of the cleavage site. Here we generate null mutations of the single Drosophila U7 gene and demonstrate that U7 snRNA is required in vivo for processing all replication-associated histone pre-mRNAs. Mutation of U7 results in the production of poly A+ histone mRNA in both proliferating and endocycling cells because of read-through to cryptic polyadenylation sites found downstream of each Drosophila histone gene. A similar molecular phenotype also results from mutation of Slbp, which encodes the protein that binds the histone mRNA 3' stem-loop. U7 null mutants develop into sterile males and females, and these females display defects during oogenesis similar to germ line clones of Slbp null cells. In contrast to U7 mutants, Slbp null mutations cause lethality. This may reflect a later onset of the histone pre-mRNA processing defect in U7 mutants compared to Slbp mutants, due to maternal stores of U7 snRNA. A double mutant combination of a viable, hypomorphic Slbp allele and a viable U7 null allele is lethal, and these double mutants express polyadenylated histone mRNAs earlier in development than either single mutant. These data suggest that SLBP and U7 snRNP cooperate in the production of histone mRNA in vivo, and that disruption of histone pre-mRNA processing is detrimental to development.
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Affiliation(s)
- Ashley C Godfrey
- Department of Biology, CB#3280, University of North Carolina, Chapel Hill, NC 27599, USA
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20
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Beckstead RB, Lam G, Thummel CS. The genomic response to 20-hydroxyecdysone at the onset of Drosophila metamorphosis. Genome Biol 2005; 6:R99. [PMID: 16356271 PMCID: PMC1414087 DOI: 10.1186/gb-2005-6-12-r99] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Revised: 08/05/2005] [Accepted: 10/20/2005] [Indexed: 05/05/2023] Open
Abstract
The genome-wide transcriptional response to 20-hydroxyecdisone at the onset of Drosophila metamorphosis, as well as its dependency on one of the ecdysone receptors is described. Background The steroid hormone 20-hydroxyecdysone (20E) triggers the major developmental transitions in Drosophila, including molting and metamorphosis, and provides a model system for defining the developmental and molecular mechanisms of steroid signaling. 20E acts via a heterodimer of two nuclear receptors, the ecdysone receptor (EcR) and Ultraspiracle, to directly regulate target gene transcription. Results Here we identify the genomic transcriptional response to 20E as well as those genes that are dependent on EcR for their proper regulation. We show that genes regulated by 20E, and dependent on EcR, account for many transcripts that are significantly up- or downregulated at puparium formation. We provide evidence that 20E and EcR participate in the regulation of genes involved in metabolism, stress, and immunity at the onset of metamorphosis. We also present an initial characterization of a 20E primary-response regulatory gene identified in this study, brain tumor (brat), showing that brat mutations lead to defects during metamorphosis and changes in the expression of key 20E-regulated genes. Conclusion This study provides a genome-wide basis for understanding how 20E and its receptor control metamorphosis, as well as a foundation for functional genomic analysis of key regulatory genes in the 20E signaling pathway during insect development.
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MESH Headings
- Animals
- Cells, Cultured
- DNA-Binding Proteins/genetics
- Drosophila Proteins/genetics
- Drosophila melanogaster/drug effects
- Drosophila melanogaster/genetics
- Drosophila melanogaster/growth & development
- Ecdysterone/pharmacology
- Gene Expression Regulation, Developmental/drug effects
- Genes, Insect/genetics
- Genes, Regulator/genetics
- Genome, Insect/drug effects
- Genome, Insect/genetics
- Immunity/genetics
- Larva/drug effects
- Larva/genetics
- Metamorphosis, Biological/drug effects
- Microarray Analysis
- Mutation/genetics
- Pupa/drug effects
- Pupa/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Steroid/genetics
- Reproducibility of Results
- Starvation/genetics
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Affiliation(s)
- Robert B Beckstead
- Department of Human Genetics, Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112-5331, USA
| | - Geanette Lam
- Department of Human Genetics, Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112-5331, USA
| | - Carl S Thummel
- Department of Human Genetics, Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112-5331, USA
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21
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Rascle A, Stowers RS, Garza D, Lepesant JA, Hogness DS. L63, the Drosophila PFTAIRE, interacts with two novel proteins unrelated to cyclins. Mech Dev 2003; 120:617-28. [PMID: 12782278 DOI: 10.1016/s0925-4773(03)00019-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
L63 encodes a CDK-like protein homologous to the mammalian PFTAIRE. We showed previously that L63 provides a CDK-related function critical to development (Dev. Biol. 221 (2000) 23). We present here the first biochemical characterization of L63 kinase. In addition, we describe two novel Drosophila proteins, PIF-1 and PIF-2 (for PFTAIRE Interacting Factor-1 and -2), identified in a two-hybrid screen for their ability to interact with the amino-terminal region of L63. The full-length PIF-1 cDNA shows an unusual dicistronic organization. PIF-1A and PIF-1B (the L63 interactor) predicted proteins are expressed in vivo, and show a distinct expression profile during development. Interaction between L63 and PIF-1B was confirmed in vitro and in vivo. The role of this interaction remains to be demonstrated, but our data suggest that PIF-1B might serve as a regulator of L63.
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Affiliation(s)
- Anne Rascle
- Departments of Biochemistry and Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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22
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Abstract
The Ashburner model for the hormonal control of polytene chromosome puffing has provided a strong foundation for understanding the basic mechanisms of steroid-regulated gene expression (Cold Spring Harbor Symp. Quant. Biol. 38 (1974) 655). According to this model, the steroid hormone 20-hydroxyecdysone (referred here as ecdysone) directly induces the expression of a small set of early regulatory genes. These genes, in turn, induce a much larger set of late target genes that play a more direct role in controlling the biological responses to the hormone. The recent characterization of two early puff genes, E63-1 and E23, and three late puff genes, D-spinophilin, L63, and L82, provide further confirmation of the Ashburner model. In addition, these studies provide exciting new directions for our understanding of ecdysone signaling. Overexpression studies of E63-1 implicate this gene in directing calcium-dependent salivary gland glue secretion. In contrast, overexpression of E23 indicates that this ABC transporter family member may negatively regulate ecdysone signaling by actively transporting the hormone out of target cells. Finally, genetic studies of the L63 and L82 late genes reveal unexpected possible functions for ecdysone in controlling developmental timing and growth. This review surveys the recent characterization of these ecdysone-inducible genes and provides an overview of how they expand our understanding of ecdysone functions during development.
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Affiliation(s)
- C S Thummel
- Department of Human Genetics, Howard Hughes Medical Institute, University of Utah, Room 5100, 15 North 2030 East, Salt Lake City, UT 84112-5331, USA.
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23
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Basso LR, Vasconcelos C, Fontes AM, Hartfelder K, Silva JA, Coelho PSR, Monesi N, Paçó-Larson ML. The induction of DNA puff BhC4-1 gene is a late response to the increase in 20-hydroxyecdysone titers in last instar dipteran larvae. Mech Dev 2002; 110:15-26. [PMID: 11744365 DOI: 10.1016/s0925-4773(01)00589-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The characterization of DNA puff BhC4-1 expression was extended and its response to 20-hydroxyecdysone investigated in Bradysia hygida and in transgenic Drosophila carrying the BhC4-1 gene. In both organisms the activation of BhC4-1 in salivary glands occurs at the end of the larval stage coinciding with the peak in ecdysone titers which induces metamorphosis. Injections of 20-hydroxyecdysone into mid-fourth instar larvae of B. hygida show that the induction of BhC4-1 expression, as well as amplification and puff C4 expansion, are late events induced by the hormone. This late response of BhC4-1 expression was also observed in transgenic salivary glands cultivated in the presence of 20-hydroxyecdysone. In vitro studies using transgenic Drosophila indicate that both repressor and activator factors regulate the timing of BhC4-1 expression in salivary glands.
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Affiliation(s)
- L R Basso
- Departamento de Biologia Celular, Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3.900, Ribeirão Preto 14049-900, SP, Brazil
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