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Challa NL, Sarkar A, Kapettu S, Phanithi PB, Chakrabarti P, Parsa KVL, Misra P. TGS1/PIMT regulates pro-inflammatory macrophage mediated paracrine insulin resistance: Crosstalk between macrophages and skeletal muscle cells. Biochim Biophys Acta Mol Basis Dis 2024; 1870:166878. [PMID: 37673359 DOI: 10.1016/j.bbadis.2023.166878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 08/30/2023] [Accepted: 09/01/2023] [Indexed: 09/08/2023]
Abstract
Macrophage-driven chronic low-grade inflammatory response is intimately associated with pathogenesis of insulin resistance and type 2 diabetes (T2D). However, the molecular basis for skewing of pro-inflammatory macrophage is still elusive. Here, we describe the mechanism and significance of TGS1/PIMT (PRIP-Interacting protein with Methyl Transferase domain) in regulating macrophage activation and polarization and its impact on the development of insulin resistance in skeletal muscle cells. We show altered expression of TGS1 in M1 polarized cultured macrophages, bone marrow-derived (BMDM) and adipose tissue macrophages. Moreover, in High Fat Diet (HFD)-fed mice enhanced TGS1 expression is predominantly localized to the nucleus of adipose tissue macrophages suggesting its potential functional role. Gain and loss of TGS1 expression in macrophage further established its role in the secretion of pro-inflammatory mediators. Mechanistically, TGS1 controls the transcription of numerous genes linked to inflammation by forming a complex with Histone Acetyl Transferase (HAT)-containing transcriptional co-activators CBP and p300. Functionally, TGS1 mediated macrophage inflammatory response induces the development of insulin resistance in skeletal muscle cells and adipocytes. Our findings thus demonstrate an unexpected contribution of TGS1 in the regulation of macrophage mediated inflammation and insulin resistance highlighting that TGS1 antagonism could be a promising therapeutic target for the management of inflammation and insulin resistance in T2D.
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Affiliation(s)
- Naga Lakshmi Challa
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life sciences, University of Hyderabad Campus, Hyderabad 500046, Telangana, India; Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, Karnataka, India; Registered as a PhD student with MAHE, Manipal, India
| | - Ankita Sarkar
- Division of Cell Biology and Physiology, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, West Bengal, India
| | - Satyamoorthy Kapettu
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, Karnataka, India
| | - Prakash Babu Phanithi
- Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad 500046, Telangana, India
| | - Partha Chakrabarti
- Division of Cell Biology and Physiology, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, West Bengal, India.
| | - Kishore V L Parsa
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life sciences, University of Hyderabad Campus, Hyderabad 500046, Telangana, India.
| | - Parimal Misra
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life sciences, University of Hyderabad Campus, Hyderabad 500046, Telangana, India.
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2
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Edwin RK, Acharya LP, Maity SK, Chakrabarti P, Tantia O, Joshi MB, Satyamoorthy K, Parsa KVL, Misra P. TGS1/PIMT knockdown reduces lipid accumulation in adipocytes, limits body weight gain and promotes insulin sensitivity in mice. Biochim Biophys Acta Mol Basis Dis 2024; 1870:166896. [PMID: 37751782 DOI: 10.1016/j.bbadis.2023.166896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 09/16/2023] [Accepted: 09/20/2023] [Indexed: 09/28/2023]
Abstract
PRIP Interacting protein with Methyl Transferase domain (PIMT/TGS1) is an integral upstream coactivator in the peroxisome proliferator-activated receptor gamma (PPARγ) transcriptional apparatus. PPARγ activation alleviates insulin resistance but promotes weight gain. Herein, we show how PIMT regulates body weight while promoting insulin sensitivity in diet induced obese mice. In vitro, we observed enhanced PIMT levels during adipogenesis. Knockdown of PIMT in 3T3-L1 results in reduced lipid accumulation and alters PPARγ regulated gene expression. Intraperitoneal injection of shPIMT lentivirus in high fat diet (HFD)-fed mice caused reduced adipose tissue size and decreased expression of lipid markers. This was accompanied by significantly lower levels of inflammation, hypertrophy and hyperplasia in the different adipose depots (eWAT and iWAT). Notably, PIMT depletion limits body weight gain in HFD-fed mice along with improved impaired oral glucose clearance. It also enhanced insulin sensitivity revealed by assessment of important insulin resistance markers and increased adiponectin levels. In addition, reduced PIMT levels did not alter the serum free fatty acid and TNFα levels. Finally, the relevance of our studies to human obesity is suggested by our finding that PIMT was upregulated in adipose tissue of obese patients along with crucial fat marker genes. We speculate that PIMT may be a potential target in maintaining energy metabolism, thus regulating obesity.
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Affiliation(s)
- Rebecca Kristina Edwin
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad 500046, India; Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104, India
| | - Lavanya Prakash Acharya
- Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104, India
| | - Sujay K Maity
- Indian Institute of Chemical Biology (CSIR-IICB), 4, Raja Subodh Chandra Mallick Rd, Poddar Nagar, Jadavpur, Kolkata, West Bengal 700032, India
| | - Partha Chakrabarti
- Indian Institute of Chemical Biology (CSIR-IICB), 4, Raja Subodh Chandra Mallick Rd, Poddar Nagar, Jadavpur, Kolkata, West Bengal 700032, India
| | - Om Tantia
- Institute of Laparoscopic Surgery Group of Hospitals, DD - 6, Sector I, Salt Lake City, Kolkata 700064, West Bengal, India
| | - Manjunath B Joshi
- Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104, India
| | - Kapaettu Satyamoorthy
- Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka 576104, India; SDM College of Medical Sciences and Hospital, Shri Dharmasthala Manjunatheshwara (SDM) University, Manjushree Nagar, Sattur, Dharwad, Karnataka 580009, India.
| | - Kishore V L Parsa
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad 500046, India.
| | - Parimal Misra
- Centre for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad 500046, India.
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3
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Siena LA, Michaud C, Selles B, Vega JM, Pessino SC, Ingouff M, Ortiz JPA, Leblanc O. TRIMETHYLGUANOSINE SYNTHASE1 mutations decanalize female germline development in Arabidopsis. THE NEW PHYTOLOGIST 2023; 240:597-612. [PMID: 37548040 DOI: 10.1111/nph.19179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 07/14/2023] [Indexed: 08/08/2023]
Abstract
Here, we report the characterization of a plant RNA methyltransferase, orthologous to yeast trimethylguanosine synthase1 (Tgs1p) and whose downregulation was associated with apomixis in Paspalum grasses. Using phylogenetic analyses and yeast complementation, we determined that land plant genomes all encode a conserved, specific TGS1 protein. Next, we studied the role of TGS1 in female reproduction using reporter lines and loss-of-function mutants in Arabidopsis thaliana. pAtTGS1:AtTGS1 reporters showed a dynamic expression pattern. They were highly active in the placenta and ovule primordia at emergence but, subsequently, showed weak signals in the nucellus. Although expressed throughout gametophyte development, activity became restricted to the female gamete and was also detected after fertilization during embryogenesis. TGS1 depletion altered the specification of the precursor cells that give rise to the female gametophytic generation and to the sporophyte, resulting in the formation of a functional aposporous-like lineage. Our results indicate that TGS1 participates in the mechanisms restricting cell fate acquisition to a single cell at critical transitions throughout the female reproductive lineage and, thus, expand our current knowledge of the mechanisms governing female reproductive fate in plants.
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Affiliation(s)
- Lorena A Siena
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | | | - Benjamin Selles
- DIADE, Univ Montpellier, IRD, CIRAD, 34394, Montpellier, France
| | - Juan Manuel Vega
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Silvina C Pessino
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Mathieu Ingouff
- DIADE, Univ Montpellier, IRD, CIRAD, 34394, Montpellier, France
| | - Juan Pablo A Ortiz
- Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina
| | - Olivier Leblanc
- DIADE, Univ Montpellier, IRD, CIRAD, 34394, Montpellier, France
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4
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Kapadia B, Behera S, Kumar ST, Shah T, Edwin RK, Babu PP, Chakrabarti P, Parsa KV, Misra P. PIMT regulates hepatic gluconeogenesis in mice. iScience 2023; 26:106120. [PMID: 36866247 PMCID: PMC9972567 DOI: 10.1016/j.isci.2023.106120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/29/2022] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
The physiological and metabolic functions of PIMT/TGS1, a third-generation transcriptional apparatus protein, in glucose homeostasis sustenance are unclear. Here, we observed that the expression of PIMT was upregulated in the livers of short-term fasted and obese mice. Lentiviruses expressing Tgs1-specific shRNA or cDNA were injected into wild-type mice. Gene expression, hepatic glucose output, glucose tolerance, and insulin sensitivity were evaluated in mice and primary hepatocytes. Genetic modulation of PIMT exerted a direct positive impact on the gluconeogenic gene expression program and hepatic glucose output. Molecular studies utilizing cultured cells, in vivo models, genetic manipulation, and PKA pharmacological inhibition establish that PKA regulates PIMT at post-transcriptional/translational and post-translational levels. PKA enhanced 3'UTR-mediated translation of TGS1 mRNA and phosphorylated PIMT at Ser656, increasing Ep300-mediated gluconeogenic transcriptional activity. The PKA-PIMT-Ep300 signaling module and associated PIMT regulation may serve as a key driver of gluconeogenesis, positioning PIMT as a critical hepatic glucose sensor.
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Affiliation(s)
- Bandish Kapadia
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India
| | - Soma Behera
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India
| | - Sireesh T. Kumar
- Department of Biotechnology, University of Hyderabad, Hyderabad 500046, India
| | - Tapan Shah
- Department of Biochemistry, Saurashtra University, Rajkot 360005, India
| | - Rebecca Kristina Edwin
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India
| | | | | | - Kishore V.L. Parsa
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India,Corresponding author
| | - Parimal Misra
- Center for Innovation in Molecular and Pharmaceutical Sciences, Dr. Reddy’s Institute of Life Sciences (DRILS), University of Hyderabad Campus, Hyderabad, TG 500046, India,Corresponding author
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5
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Spotting the Targets of the Apospory Controller TGS1 in Paspalum notatum. PLANTS 2022; 11:plants11151929. [PMID: 35893633 PMCID: PMC9332697 DOI: 10.3390/plants11151929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/27/2022] [Accepted: 06/30/2022] [Indexed: 11/17/2022]
Abstract
Sexuality and apomixis are interconnected plant reproductive routes possibly behaving as polyphenic traits under the influence of the environment. In the subtropical grass Paspalum notatum, one of the controllers of apospory, a main component of gametophytic apomixis reproduction, is TRIMETHYLGUANOSINE SYNTHASE 1 (TGS1), a multifunctional gene previously associated with RNA cleavage regulation (including mRNA splicing as well as rRNA and miRNA processing), transcriptional modulation and the establishment of heterochromatin. In particular, the downregulation of TGS1 induces a sexuality decline and the emergence of aposporous-like embryo sacs. The present work was aimed at identifying TGS1 target RNAs expressed during reproductive development of Paspalum notatum. First, we mined available RNA databases originated from spikelets of sexual and apomictic plants, which naturally display a contrasting TGS1 representation, to identify differentially expressed mRNA splice variants and miRNAs. Then, the role of TGS1 in the generation of these particular molecules was investigated in antisense tgs1 sexual lines. We found that CHLOROPHYLL A-B BINDING PROTEIN 1B-21 (LHC Ib-21, a component of the chloroplast light harvesting complex), QUI-GON JINN (QGJ, encoding a MAP3K previously associated with apomixis) and miR2275 (a meiotic 24-nt phasi-RNAs producer) are directly or indirectly targeted by TGS1. Our results point to a coordinated control exercised by signal transduction and siRNA machineries to induce the transition from sexuality to apomixis.
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6
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PIMT/TGS1: an evolving metabolic molecular switch with conserved methyl transferase activity. Drug Discov Today 2022; 27:2386-2393. [DOI: 10.1016/j.drudis.2022.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 03/01/2022] [Accepted: 04/14/2022] [Indexed: 11/18/2022]
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7
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Trimethylguanosine synthase 1 is a novel regulator of pancreatic beta-cell mass and function. J Biol Chem 2022; 298:101592. [PMID: 35041827 PMCID: PMC8861161 DOI: 10.1016/j.jbc.2022.101592] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/06/2022] [Accepted: 01/08/2022] [Indexed: 01/23/2023] Open
Abstract
Type 2 diabetes is a metabolic disorder associated with abnormal glucose homeostasis and is characterized by intrinsic defects in β-cell function and mass. Trimethylguanosine synthase 1 (TGS1) is an evolutionarily conserved enzyme that methylates small nuclear and nucleolar RNAs and that is involved in pre-mRNA splicing, transcription, and ribosome production. However, the role of TGS1 in β-cells and glucose homeostasis had not been explored. Here, we show that TGS1 is upregulated by insulin and upregulated in islets of Langerhans from mice exposed to a high-fat diet and in human β-cells from type 2 diabetes donors. Using mice with conditional (βTGS1KO) and inducible (MIP-CreERT-TGS1KO) TGS1 deletion, we determined that TGS1 regulates β-cell mass and function. Using unbiased approaches, we identified a link between TGS1 and endoplasmic reticulum stress and cell cycle arrest, as well as and how TGS1 regulates β-cell apoptosis. We also found that deletion of TGS1 results in an increase in the unfolded protein response by increasing XBP-1, ATF-4, and the phosphorylation of eIF2α, in addition to promoting several changes in cell cycle inhibitors and activators such as p27 and Cyclin D2. This study establishes TGS1 as a key player regulating β-cell mass and function. We propose that these observations can be used as a stepping-stone for the design of novel strategies focused on TGS1 as a therapeutic target for the treatment of diabetes.
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8
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Johnson KR, Mallon BS, Fann YC, Chen KG. Multivariate meta-analysis reveals global transcriptomic signatures underlying distinct human naive-like pluripotent states. PLoS One 2021; 16:e0251461. [PMID: 33984026 PMCID: PMC8118304 DOI: 10.1371/journal.pone.0251461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 04/27/2021] [Indexed: 11/19/2022] Open
Abstract
The ground or naive pluripotent state of human pluripotent stem cells (hPSCs), which was initially established in mouse embryonic stem cells (mESCs), is an emerging and tentative concept. To verify this vital concept in hPSCs, we performed a multivariate meta-analysis of major hPSC datasets via the combined analytic powers of percentile normalization, principal component analysis (PCA), t-distributed stochastic neighbor embedding (t-SNE), and SC3 consensus clustering. This robust bioinformatics approach has significantly improved the predictive values of our meta-analysis. Accordingly, we revealed various similarities or dissimilarities between some naive-like hPSCs (NLPs) generated from different laboratories. Our analysis confirms some previous studies and provides new evidence concerning the existence of three distinct naive-like pluripotent states. Moreover, our study offers global transcriptomic markers that define diverse pluripotent states under various hPSC growth protocols.
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Affiliation(s)
- Kory R. Johnson
- Intramural IT and Bioinformatics Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (KRJ); (KGC)
| | - Barbara S. Mallon
- NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yang C. Fann
- Intramural IT and Bioinformatics Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kevin G. Chen
- NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (KRJ); (KGC)
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9
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Cheng L, Zhang Y, Zhang Y, Chen T, Xu YZ, Rong YS. Loss of the RNA trimethylguanosine cap is compatible with nuclear accumulation of spliceosomal snRNAs but not pre-mRNA splicing or snRNA processing during animal development. PLoS Genet 2020; 16:e1009098. [PMID: 33085660 PMCID: PMC7605716 DOI: 10.1371/journal.pgen.1009098] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 11/02/2020] [Accepted: 09/07/2020] [Indexed: 12/31/2022] Open
Abstract
The 2,2,7-trimethylguanosine (TMG) cap is one of the first identified modifications on eukaryotic RNAs. TMG, synthesized by the conserved Tgs1 enzyme, is abundantly present on snRNAs essential for pre-mRNA splicing. Results from ex vivo experiments in vertebrate cells suggested that TMG ensures nuclear localization of snRNAs. Functional studies of TMG using tgs1 mutations in unicellular organisms yield results inconsistent with TMG being indispensable for either nuclear import or splicing. Utilizing a hypomorphic tgs1 mutation in Drosophila, we show that TMG reduction impairs germline development by disrupting the processing, particularly of introns with smaller sizes and weaker splice sites. Unexpectedly, loss of TMG does not disrupt snRNAs localization to the nucleus, disputing an essential role of TMG in snRNA transport. Tgs1 loss also leads to defective 3' processing of snRNAs. Remarkably, stronger tgs1 mutations cause lethality without severely disrupting splicing, likely due to the preponderance of TMG-capped snRNPs. Tgs1, a predominantly nucleolar protein in Drosophila, likely carries out splicing-independent functions indispensable for animal development. Taken together, our results suggest that nuclear import is not a conserved function of TMG. As a distinctive structure on RNA, particularly non-coding RNA, we suggest that TMG prevents spurious interactions detrimental to the function of RNAs that it modifies.
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Affiliation(s)
- Lin Cheng
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- Hengyang College of Medicine, University of South China, Hengyang, China
| | - Yu Zhang
- Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Yi Zhang
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States of America
| | - Tao Chen
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- Hengyang College of Medicine, University of South China, Hengyang, China
| | - Yong-Zhen Xu
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Yikang S. Rong
- Hengyang College of Medicine, University of South China, Hengyang, China
- * E-mail:
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10
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Maccallini P, Bavasso F, Scatolini L, Bucciarelli E, Noviello G, Lisi V, Palumbo V, D'Angeli S, Cacchione S, Cenci G, Ciapponi L, Wakefield JG, Gatti M, Raffa GD. Intimate functional interactions between TGS1 and the Smn complex revealed by an analysis of the Drosophila eye development. PLoS Genet 2020; 16:e1008815. [PMID: 32453722 PMCID: PMC7289441 DOI: 10.1371/journal.pgen.1008815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/11/2020] [Accepted: 04/30/2020] [Indexed: 11/27/2022] Open
Abstract
Trimethylguanosine synthase 1 (TGS1) is a conserved enzyme that mediates formation of the trimethylguanosine cap on several RNAs, including snRNAs and telomerase RNA. Previous studies have shown that TGS1 binds the Survival Motor Neuron (SMN) protein, whose deficiency causes spinal muscular atrophy (SMA). Here, we analyzed the roles of the Drosophila orthologs of the human TGS1 and SMN genes. We show that the Drosophila TGS1 protein (dTgs1) physically interacts with all subunits of the Drosophila Smn complex (Smn, Gem2, Gem3, Gem4 and Gem5), and that a human TGS1 transgene rescues the mutant phenotype caused by dTgs1 loss. We demonstrate that both dTgs1 and Smn are required for viability of retinal progenitor cells and that downregulation of these genes leads to a reduced eye size. Importantly, overexpression of dTgs1 partially rescues the eye defects caused by Smn depletion, and vice versa. These results suggest that the Drosophila eye model can be exploited for screens aimed at the identification of genes and drugs that modify the phenotypes elicited by Tgs1 and Smn deficiency. These modifiers could help to understand the molecular mechanisms underlying SMA pathogenesis and devise new therapies for this genetic disease. We explored the functional relationships between TGS1 and SMN using Drosophila as model organism. TGS1 is an enzyme that modifies the structure of the 5’-end of several RNAs, including telomerase RNA and the small nuclear RNAs (snRNAs) that are required for messenger RNA maturation. The SMN protein regulates snRNAs biogenesis and mutations in human SMN cause Spinal Muscular Atrophy (SMA), a devastating disorder characterized by neurodegeneration, progressive paralysis and death. We show that mutations in the Drosophila TGS1 (dTgs1) gene cause lethality, which is rescued by a human TGS1 transgene. We also show that the dTgs1 protein physically interacts with all subunits of the Smn complex, and that downregulation of either dTgs1 or Smn leads to a reduced Drosophila eye size. Notably, overexpression of dTgs1 partially rescues the eye defects caused by Smn knockdown, and vice versa, indicating that these genes cooperate in eye development. These results suggest that the eye model can be exploited for screens aimed at detection of chemical and genetic modifiers of the eye mutant phenotype elicited by dTgs1 and Smn deficiency, providing new clues about SMA pathogenesis and potential therapies.
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Affiliation(s)
- Paolo Maccallini
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Livia Scatolini
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | | | - Gemma Noviello
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Veronica Lisi
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Valeria Palumbo
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Simone D'Angeli
- Dipartimento di Biologia Ambientale, Sapienza University of Rome, Rome, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Giovanni Cenci
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- Fondazione Cenci Bolognetti, Istituto Pasteur, Rome, Italy
| | - Laura Ciapponi
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - James G. Wakefield
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, United Kingdom
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Rome, Italy
- * E-mail: (MG); (GDR)
| | - Grazia Daniela Raffa
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- * E-mail: (MG); (GDR)
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11
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Jia Y, Liu N, Viswakarma N, Sun R, Schipma MJ, Shang M, Thorp EB, Kanwar YS, Thimmapaya B, Reddy JK. PIMT/NCOA6IP Deletion in the Mouse Heart Causes Delayed Cardiomyopathy Attributable to Perturbation in Energy Metabolism. Int J Mol Sci 2018; 19:ijms19051485. [PMID: 29772707 PMCID: PMC5983783 DOI: 10.3390/ijms19051485] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 05/03/2018] [Accepted: 05/09/2018] [Indexed: 01/09/2023] Open
Abstract
PIMT/NCOA6IP, a transcriptional coactivator PRIP/NCOA6 binding protein, enhances nuclear receptor transcriptional activity. Germline disruption of PIMT results in early embryonic lethality due to impairment of development around blastocyst and uterine implantation stages. We now generated mice with Cre-mediated cardiac-specific deletion of PIMT (csPIMT−/−) in adult mice. These mice manifest enlargement of heart, with nearly 100% mortality by 7.5 months of age due to dilated cardiomyopathy. Significant reductions in the expression of genes (i) pertaining to mitochondrial respiratory chain complexes I to IV; (ii) calcium cycling cardiac muscle contraction (Atp2a1, Atp2a2, Ryr2); and (iii) nuclear receptor PPAR- regulated genes involved in glucose and fatty acid energy metabolism were found in csPIMT−/− mouse heart. Elevated levels of Nppa and Nppb mRNAs were noted in csPIMT−/− heart indicative of myocardial damage. These hearts revealed increased reparative fibrosis associated with enhanced expression of Tgfβ2 and Ctgf. Furthermore, cardiac-specific deletion of PIMT in adult mice, using tamoxifen-inducible Cre-approach (TmcsPIMT−/−), results in the development of cardiomyopathy. Thus, cumulative evidence suggests that PIMT functions in cardiac energy metabolism by interacting with nuclear receptor coactivators and this property could be useful in the management of heart failure.
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Affiliation(s)
- Yuzhi Jia
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Ning Liu
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Navin Viswakarma
- Department of Surgery, Division of Surgical Oncology, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Ruya Sun
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Mathew J Schipma
- Next Generation Sequencing Core Facility, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Meng Shang
- Feinberg Cardiovascular Research Institute and Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Edward B Thorp
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Yashpal S Kanwar
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Bayar Thimmapaya
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Janardan K Reddy
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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12
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Gao J, Wallis JG, Jewell JB, Browse J. Trimethylguanosine Synthase1 (TGS1) Is Essential for Chilling Tolerance. PLANT PHYSIOLOGY 2017; 174:1713-1727. [PMID: 28495891 PMCID: PMC5490903 DOI: 10.1104/pp.17.00340] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/09/2017] [Indexed: 05/20/2023]
Abstract
Chilling stress is a major factor limiting plant development and crop productivity. Because the plant response to chilling is so complex, we are far from understanding the genes important in the response to chilling. To identify new genes important in chilling tolerance, we conducted a novel mutant screen, combining a confirmed SALK T-DNA insertion collection with traditional forward genetics. We screened a pool of more than 3700 confirmed homozygous SALK T-DNA insertion lines for visible defects under prolonged growth at 5°C. Of the chilling-sensitive mutants we observed, mutations at one locus were characterized in detail. This gene, At1g45231, encodes an Arabidopsis (Arabidopsis thaliana) trimethylguanosine synthase (TGS1), previously uncharacterized in the plant kingdom. We confirmed that Arabidopsis TGS1 is a functional ortholog of other trimethylguanosine synthases based both on its in vitro methyltransferase activity and on its ability to rescue the cold-growth inhibition of a Saccharomyces cerevisiae tgs1Δ mutant in vivo. While tgs1 mutant plants grew normally at 22°C, their vegetative and reproductive growth was severely compromised under chilling conditions. When we transgenically expressed TGS1 in the mutant plants, the chilling-sensitive phenotype was relieved, demonstrating that TGS1 is required for chilling tolerance.
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Affiliation(s)
- Jinpeng Gao
- Institute of Biological Chemistry, Clark Hall, Washington State University, Pullman, Washington 99164-6340
| | - James G Wallis
- Institute of Biological Chemistry, Clark Hall, Washington State University, Pullman, Washington 99164-6340
| | - Jeremy B Jewell
- Institute of Biological Chemistry, Clark Hall, Washington State University, Pullman, Washington 99164-6340
| | - John Browse
- Institute of Biological Chemistry, Clark Hall, Washington State University, Pullman, Washington 99164-6340
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13
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Martinez I, Hayes KE, Barr JA, Harold AD, Xie M, Bukhari SIA, Vasudevan S, Steitz JA, DiMaio D. An Exportin-1-dependent microRNA biogenesis pathway during human cell quiescence. Proc Natl Acad Sci U S A 2017; 114:E4961-E4970. [PMID: 28584122 PMCID: PMC5488920 DOI: 10.1073/pnas.1618732114] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The reversible state of proliferative arrest known as "cellular quiescence" plays an important role in tissue homeostasis and stem cell biology. By analyzing the expression of miRNAs and miRNA-processing factors during quiescence in primary human fibroblasts, we identified a group of miRNAs that are induced during quiescence despite markedly reduced expression of Exportin-5, a protein required for canonical miRNA biogenesis. The biogenesis of these quiescence-induced miRNAs is independent of Exportin-5 and depends instead on Exportin-1. Moreover, these quiescence-induced primary miRNAs (pri-miRNAs) are modified with a 2,2,7-trimethylguanosine (TMG)-cap, which is known to bind Exportin-1, and knockdown of Exportin-1 or trimethylguanosine synthase 1, responsible for (TMG)-capping, inhibits their biogenesis. Surprisingly, in quiescent cells Exportin-1-dependent pri-miR-34a is present in the cytoplasm together with a small isoform of Drosha, implying the existence of a different miRNA processing pathway in these cells. Our findings suggest that during quiescence the canonical miRNA biogenesis pathway is down-regulated and specific miRNAs are generated by an alternative pathway to regulate genes involved in cellular growth arrest.
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Affiliation(s)
- Ivan Martinez
- Department of Microbiology, West Virginia University Cancer Institute, West Virginia University, Morgantown, WV 26506;
| | - Karen E Hayes
- Department of Microbiology, West Virginia University Cancer Institute, West Virginia University, Morgantown, WV 26506
| | - Jamie A Barr
- Department of Microbiology, West Virginia University Cancer Institute, West Virginia University, Morgantown, WV 26506
| | - Abby D Harold
- Department of Microbiology, West Virginia University Cancer Institute, West Virginia University, Morgantown, WV 26506
| | - Mingyi Xie
- Department of Biochemistry and Molecular Biology, University of Florida Health Cancer Center, University of Florida, Gainesville, FL 32610
| | - Syed I A Bukhari
- Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
| | - Shobha Vasudevan
- Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
| | - Joan A Steitz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06536;
- Howard Hughes Medical Institute, Yale University, New Haven, CT 06536
- Yale Cancer Center, New Haven, CT 06520
| | - Daniel DiMaio
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06536
- Yale Cancer Center, New Haven, CT 06520
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT 06510
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14
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An insertion in the methyltransferase domain of P. falciparum trimethylguanosine synthase harbors a classical nuclear localization signal. Mol Biochem Parasitol 2016; 210:58-70. [PMID: 27619053 DOI: 10.1016/j.molbiopara.2016.08.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 08/12/2016] [Accepted: 08/31/2016] [Indexed: 01/27/2023]
Abstract
Many Plasmodium falciparum proteins do not share homology with, and are generally longer than their respective orthologs. This, to some extent, can be attributed to insertions. Here, we studied a P. falciparum RNA hypermethylase, trimethylguanosine synthase (PfTGS1) that harbors a 76 amino acid insertion in its methyltransferase domain. Bioinformatics analysis revealed that this insertion was present in TGS1 orthologs from other Plasmodium species as well. Interestingly, a classical nuclear localization signal (NLS) was predicted in the insertions of primate parasite TGS1 proteins. To check whether these predicted NLS are functional, we developed an in vivo heterologous system using S. cerevisiae. The predicted NLS when fused to dimeric GFP were able to localize the fusion protein to the nucleus in yeast indicating that it is indeed recognized by the yeast nuclear import machinery. We further showed that the PfTGS1 NLS binds to P. falciparum importin-α in vitro, confirming that the NLS is also recognized by the P. falciparum classical nuclear import machinery. Thus, in this study we report a novel function of the insertion in PfTGS1.
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15
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Borg RM, Fenech Salerno B, Vassallo N, Bordonne R, Cauchi RJ. Disruption of snRNP biogenesis factors Tgs1 and pICln induces phenotypes that mirror aspects of SMN-Gemins complex perturbation in Drosophila, providing new insights into spinal muscular atrophy. Neurobiol Dis 2016; 94:245-58. [PMID: 27388936 DOI: 10.1016/j.nbd.2016.06.015] [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: 10/26/2015] [Revised: 06/20/2016] [Accepted: 06/27/2016] [Indexed: 01/27/2023] Open
Abstract
The neuromuscular disorder, spinal muscular atrophy (SMA), results from insufficient levels of the survival motor neuron (SMN) protein. Together with Gemins 2-8 and Unrip, SMN forms the large macromolecular SMN-Gemins complex, which is known to be indispensable for chaperoning the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). It remains unclear whether disruption of this function is responsible for the selective neuromuscular degeneration in SMA. In the present study, we first show that loss of wmd, the Drosophila Unrip orthologue, has a negative impact on the motor system. However, due to lack of a functional relationship between wmd/Unrip and Gemin3, it is likely that Unrip joined the SMN-Gemins complex only recently in evolution. Second, we uncover that disruption of either Tgs1 or pICln, two cardinal players in snRNP biogenesis, results in viability and motor phenotypes that closely resemble those previously uncovered on loss of the constituent members of the SMN-Gemins complex. Interestingly, overexpression of both factors leads to motor dysfunction in Drosophila, a situation analogous to that of Gemin2. Toxicity is conserved in the yeast S. pombe where pICln overexpression induces a surplus of Sm proteins in the cytoplasm, indicating that a block in snRNP biogenesis is partly responsible for this phenotype. Importantly, we show a strong functional relationship and a physical interaction between Gemin3 and either Tgs1 or pICln. We propose that snRNP biogenesis is the pathway connecting the SMN-Gemins complex to a functional neuromuscular system, and its disturbance most likely leads to the motor dysfunction that is typical in SMA.
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Affiliation(s)
- Rebecca M Borg
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta; Institut de Génétique Moléculaire de Montpellier, CNRS-UMR5535, Université Montpellier 1 and 2, Montpellier, France
| | - Benji Fenech Salerno
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Neville Vassallo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta
| | - Rémy Bordonne
- Institut de Génétique Moléculaire de Montpellier, CNRS-UMR5535, Université Montpellier 1 and 2, Montpellier, France
| | - Ruben J Cauchi
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Centre for Molecular Medicine and Biobanking, Biomedical Sciences Building, University of Malta, Msida, Malta.
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Obeid JP, Zafar N, El Hokayem J. Steroid Hormone Receptor Coregulators in Endocrine Cancers. IUBMB Life 2016; 68:504-15. [PMID: 27240871 DOI: 10.1002/iub.1517] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/11/2016] [Accepted: 05/11/2016] [Indexed: 01/14/2023]
Abstract
Coregulators span a broad and extensive domain in modulating cellular transcriptional activity. Studies have established a dynamic role for such coregulators in various endocrine cancers. Steroid hormone receptors (SHRs) play a pivotal role in such endocrine cancers, and interact abundantly with transcriptional coregulators in altering gene expression. Several families of coregulators have implications in propagating the development, progression and invasion of breast, prostate, and other hormone-responsive cancers. This mini-review aims to discuss different classes of coregulators involved in endocrine cancers and highlight unique information regarding each family with relevance to mechanism, intervention, and novel directions being investigated. © 2016 IUBMB Life, 68(7):504-515, 2016.
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Affiliation(s)
- Jean-Pierre Obeid
- Department of Biochemistry and Molecular Biology, University of Miami, FL, USA
| | - Nawal Zafar
- Department of Biochemistry and Molecular Biology, University of Miami, FL, USA
| | - Jimmy El Hokayem
- Department of Biochemistry and Molecular Biology, University of Miami, FL, USA
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17
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Youssef J, Badr M. Peroxisome Proliferator-Activated Receptors Features, Functions, and Future. NUCLEAR RECEPTOR RESEARCH 2015. [DOI: 10.11131/2015/101188] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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18
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Co-activator binding protein PIMT mediates TNF-α induced insulin resistance in skeletal muscle via the transcriptional down-regulation of MEF2A and GLUT4. Sci Rep 2015; 5:15197. [PMID: 26468734 PMCID: PMC4606566 DOI: 10.1038/srep15197] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 09/21/2015] [Indexed: 12/18/2022] Open
Abstract
The mechanisms underlying inflammation induced insulin resistance are poorly understood. Here, we report that the expression of PIMT, a transcriptional co-activator binding protein, was up-regulated in the soleus muscle of high sucrose diet (HSD) induced insulin resistant rats and TNF-α exposed cultured myoblasts. Moreover, TNF-α induced phosphorylation of PIMT at the ERK1/2 target site Ser298. Wild type (WT) PIMT or phospho-mimic Ser298Asp mutant but not phospho-deficient Ser298Ala PIMT mutant abrogated insulin stimulated glucose uptake by L6 myotubes and neonatal rat skeletal myoblasts. Whereas, PIMT knock down relieved TNF-α inhibited insulin signaling. Mechanistic analysis revealed that PIMT differentially regulated the expression of GLUT4, MEF2A, PGC-1α and HDAC5 in cultured cells and skeletal muscle of Wistar rats. Further characterization showed that PIMT was recruited to GLUT4, MEF2A and HDAC5 promoters and overexpression of PIMT abolished the activity of WT but not MEF2A binding defective mutant GLUT4 promoter. Collectively, we conclude that PIMT mediates TNF-α induced insulin resistance at the skeletal muscle via the transcriptional modulation of GLUT4, MEF2A, PGC-1α and HDAC5 genes.
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19
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Boon KL, Pearson MD, Koš M. Self-association of Trimethylguanosine Synthase Tgs1 is required for efficient snRNA/snoRNA trimethylation and pre-rRNA processing. Sci Rep 2015; 5:11282. [PMID: 26074133 PMCID: PMC4466884 DOI: 10.1038/srep11282] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/21/2015] [Indexed: 12/23/2022] Open
Abstract
Trimethylguanosine Synthase catalyses transfer of two methyl groups to the m7G cap of RNA polymerase II transcribed snRNAs, snoRNAs, and telomerase RNA TLC1 to form a 2,2,7-trimethylguanosine cap. While in vitro studies indicate that Tgs1 functions as a monomer and the dimethylation of m7G caps is not a processive reaction, partially methylated sn(o)RNAs are typically not detected in living cells. Here we show that both yeast and human Tgs1p possess a conserved self-association property located at the N-terminus. A disruption of Tgs1 self-association led to a strong reduction of sn(o)RNA trimethylation as well as reduced nucleolar enrichment of Tgs1. Self-association of Tgs1p and its catalytic activity were also prerequisite to bypass the requirement for its accessory factor Swm2p for efficient pre-rRNA processing and snRNA trimethylation. The ability to self-associate might enable Tgs1 to efficiently dimethylate the caps of the targeted RNAs in vivo.
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Affiliation(s)
- Kum-Loong Boon
- 1] Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany [2] Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Michael David Pearson
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Martin Koš
- Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
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20
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Siena LA, Ortiz JPA, Leblanc O, Pessino S. PnTgs1-like expression during reproductive development supports a role for RNA methyltransferases in the aposporous pathway. BMC PLANT BIOLOGY 2014; 14:297. [PMID: 25404464 PMCID: PMC4243328 DOI: 10.1186/s12870-014-0297-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Accepted: 10/20/2014] [Indexed: 05/19/2023]
Abstract
BACKGROUND In flowering plants, apomixis (asexual reproduction via seeds) is widely believed to result from failure of key regulators of the sexual female reproductive pathway. In the past few years, both differential display and RNA-seq comparative approaches involving reproductive organs of sexual plants and their apomictic counterparts have yielded extensive lists of candidate genes. Nevertheless, only a limited number of these genes have been functionally characterized, with few clues consequently available for understanding the molecular control of apomixis. We have previously identified several cDNA fragments with high similarity to genes involved in RNA biology and with differential amplification between sexual and apomictic Paspalum notatum plants. Here, we report the characterization of one of these candidates, namely, N69 encoding a protein of the S-adenosyl-L-methionine-dependent methyltransferases superfamily. The purpose of this work was to extend the N69 cDNA sequence and to characterize its expression at different developmental stages in both sexual and apomictic individuals. RESULTS Molecular characterization of the N69 cDNA revealed homology with genes encoding proteins similar to yeast and mammalian trimethylguanosine synthase/PRIP-interacting proteins. These proteins play a dual role as ERK2-controlled transcriptional coactivators and mediators of sn(o)RNA and telomerase RNA cap trimethylation, and participate in mammals and yeast development. The N69-extended sequence was consequently renamed PnTgs1-like. Expression of PnTgs1-like during reproductive development was significantly higher in floral organs of sexual genotypes compared with apomicts. This difference was not detected in vegetative tissues. In addition, expression levels in reproductive tissues of several genotypes were negatively correlated with facultative apomixis rates. Moreover, in situ hybridization observations revealed that PnTgs1-like expression is relatively higher in ovules of sexual plants throughout development, from premeiosis to maturity. Tissues where differential expression is detected include nucellar cells, the site of aposporous initials differentiation in apomictic genotypes. CONCLUSIONS Our results indicate that PnTgs1-like (formerly N69) encodes a trimethylguanosine synthase-like protein whose function in mammals and yeast is critical for development, including reproduction. Our findings also suggest a pivotal role for this candidate gene in nucellar cell fate, as its diminished expression is correlated with initiation of the apomictic pathway in plants.
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Affiliation(s)
- Lorena A Siena
- />Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Parque Villarino, (S2125ZAA) Zavalla, Santa Fe, Argentina
| | - Juan Pablo A Ortiz
- />Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Parque Villarino, (S2125ZAA) Zavalla, Santa Fe, Argentina
- />Instituto de Botánica del Nordeste -IBONE- (UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Sargento Cabral 2131, 3400 Corrientes, Argentina
| | - Olivier Leblanc
- />Institut de Recherche pour le Développement, ERL 5300 IRD/CNRS, UMR 232 IRD/Université de Montpellier 2, 911 Avenue Agropolis, Montpellier, France
| | - Silvina Pessino
- />Laboratorio de Biología Molecular, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Parque Villarino, (S2125ZAA) Zavalla, Santa Fe, Argentina
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21
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Kapadia B, Viswakarma N, Parsa KVL, Kain V, Behera S, Suraj SK, Babu PP, Kar A, Panda S, Zhu YJ, Jia Y, Thimmapaya B, Reddy JK, Misra P. ERK2-mediated phosphorylation of transcriptional coactivator binding protein PIMT/NCoA6IP at Ser298 augments hepatic gluconeogenesis. PLoS One 2013; 8:e83787. [PMID: 24358311 PMCID: PMC3866170 DOI: 10.1371/journal.pone.0083787] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 11/08/2013] [Indexed: 12/22/2022] Open
Abstract
PRIP-Interacting protein with methyl transferase domain (PIMT) serves as a molecular bridge between CREB-binding protein (CBP)/ E1A binding protein p300 (Ep300) -anchored histone acetyl transferase and the Mediator complex sub-unit1 (Med1) and modulates nuclear receptor transcription. Here, we report that ERK2 phosphorylates PIMT at Ser(298) and enhances its ability to activate PEPCK promoter. We observed that PIMT is recruited to PEPCK promoter and adenoviral-mediated over-expression of PIMT in rat primary hepatocytes up-regulated expression of gluconeogenic genes including PEPCK. Reporter experiments with phosphomimetic PIMT mutant (PIMT(S298D)) suggested that conformational change may play an important role in PIMT-dependent PEPCK promoter activity. Overexpression of PIMT and Med1 together augmented hepatic glucose output in an additive manner. Importantly, expression of gluconeogenic genes and hepatic glucose output were suppressed in isolated liver specific PIMT knockout mouse hepatocytes. Furthermore, consistent with reporter experiments, PIMT(S298D) but not PIMT(S298A) augmented hepatic glucose output via up-regulating the expression of gluconeogenic genes. Pharmacological blockade of MAPK/ERK pathway using U0126, abolished PIMT/Med1-dependent gluconeogenic program leading to reduced hepatic glucose output. Further, systemic administration of T4 hormone to rats activated ERK1/2 resulting in enhanced PIMT ser(298) phosphorylation. Phosphorylation of PIMT led to its increased binding to the PEPCK promoter, increased PEPCK expression and induction of gluconeogenesis in liver. Thus, ERK2-mediated phosphorylation of PIMT at Ser(298) is essential in hepatic gluconeogenesis, demonstrating an important role of PIMT in the pathogenesis of hyperglycemia.
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Affiliation(s)
- Bandish Kapadia
- Department of Biology, Dr Reddy’s Institute of Life Sciences, An Associate Institute of University of Hyderabad, Hyderabad, Andhra Pradesh, India
| | - Navin Viswakarma
- Department of Biology, Dr Reddy’s Institute of Life Sciences, An Associate Institute of University of Hyderabad, Hyderabad, Andhra Pradesh, India
| | - Kishore V. L. Parsa
- Department of Biology, Dr Reddy’s Institute of Life Sciences, An Associate Institute of University of Hyderabad, Hyderabad, Andhra Pradesh, India
| | - Vasundhara Kain
- Department of Biology, Dr Reddy’s Institute of Life Sciences, An Associate Institute of University of Hyderabad, Hyderabad, Andhra Pradesh, India
| | - Soma Behera
- Department of Biology, Dr Reddy’s Institute of Life Sciences, An Associate Institute of University of Hyderabad, Hyderabad, Andhra Pradesh, India
| | - Sashidhara Kaimal Suraj
- Department of Biotechnology, School of Life Sciences, University of Hyderabad, Hyderabad, Andhra Pradesh, India
| | - Phanithi Prakash Babu
- Department of Biotechnology, School of Life Sciences, University of Hyderabad, Hyderabad, Andhra Pradesh, India
| | - Anand Kar
- Department of Life Sciences, Devi Ahilya University, Indore, Madhya Pradesh, India
| | - Sunanda Panda
- Department of Life Sciences, Devi Ahilya University, Indore, Madhya Pradesh, India
| | - Yi-jun Zhu
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Yuzhi Jia
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Bayar Thimmapaya
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Janardan K. Reddy
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail: (PM); (JKR)
| | - Parimal Misra
- Department of Biology, Dr Reddy’s Institute of Life Sciences, An Associate Institute of University of Hyderabad, Hyderabad, Andhra Pradesh, India
- * E-mail: (PM); (JKR)
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22
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Putting an 'End' to HIV mRNAs: capping and polyadenylation as potential therapeutic targets. AIDS Res Ther 2013; 10:31. [PMID: 24330569 PMCID: PMC3874655 DOI: 10.1186/1742-6405-10-31] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 11/26/2013] [Indexed: 01/27/2023] Open
Abstract
Like most cellular mRNAs, the 5′ end of HIV mRNAs is capped and the 3′ end matured by the process of polyadenylation. There are, however, several rather unique and interesting aspects of these post-transcriptional processes on HIV transcripts. Capping of the highly structured 5′ end of HIV mRNAs is influenced by the viral TAT protein and a population of HIV mRNAs contains a trimethyl-G cap reminiscent of U snRNAs involved in splicing. HIV polyadenylation involves active repression of a promoter-proximal polyadenylation signal, auxiliary upstream regulatory elements and moonlighting polyadenylation factors that have additional impacts on HIV biology outside of the constraints of classical mRNA 3’ end formation. This review describes these post-transcriptional novelties of HIV gene expression as well as their implications in viral biology and as possible targets for therapeutic intervention.
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23
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Misra P, Viswakarma N, Reddy JK. Peroxisome proliferator-activated receptor-α signaling in hepatocarcinogenesis. Subcell Biochem 2013; 69:77-99. [PMID: 23821144 DOI: 10.1007/978-94-007-6889-5_5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Peroxisomes are subcellular organelles that are found in the cytoplasm of most animal cells. They perform diverse metabolic functions, including H2O2-derived respiration, β-oxidation of fatty acids, and cholesterol metabolism. Peroxisome proliferators are a large class of structurally dissimilar industrial and pharmaceutical chemicals that were originally identified as inducers of both the size and the number of peroxisomes in rat and mouse livers or hepatocytes in vitro. Exposure to peroxisome proliferators leads to a stereotypical orchestration of adaptations consisting of hepatocellular hypertrophy and hyperplasia, and transcriptional induction of fatty acid metabolizing enzymes regulated in parallel with peroxisome proliferation. Chronic exposure to peroxisome proliferators causes liver tumors in both male and female mice and rats. Evidence indicates a pivotal role for a subset of nuclear receptor superfamily members, called peroxisome proliferator-activated receptors (PPARs), in mediating energy metabolism. Upon activation, PPARs regulate the expression of genes involved in lipid metabolism and peroxisome proliferation, as well as genes involved in cell growth. In this review, we describe the molecular mode of action of PPAR transcription factors, including ligand binding, interaction with specific DNA response elements, transcriptional activation, and cross talk with other signaling pathways. We discuss the evidence that suggests that PPARα and transcriptional coactivator Med1/PBP, a key subunit of the Mediator complex play a central role in mediating hepatic steatosis to hepatocarcinogenesis. Disproportionate increases in H2O2-generating enzymes generates excess reactive oxygen species resulting in sustained oxidative stress and progressive endoplasmic reticulum (ER) stress with activation of unfolded protein response signaling. Thus, these major contributors coupled with hepatocellular proliferation are the key players of peroxisome proliferators-induced hepatocarcinogenesis.
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Affiliation(s)
- Parimal Misra
- Department of Biology, Dr. Reddy's Institute of Life Sciences, An Associate Institute of University of Hyderabad, Gachibowli, Hyderabad, 500046, India,
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24
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Pyper SR, Viswakarma N, Yu S, Reddy JK. PPARalpha: energy combustion, hypolipidemia, inflammation and cancer. NUCLEAR RECEPTOR SIGNALING 2010; 8:e002. [PMID: 20414453 PMCID: PMC2858266 DOI: 10.1621/nrs.08002] [Citation(s) in RCA: 293] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Accepted: 03/04/2010] [Indexed: 12/11/2022]
Abstract
The peroxisome proliferator-activated receptor alpha (PPARalpha, or NR1C1) is a nuclear hormone receptor activated by a structurally diverse array of synthetic chemicals known as peroxisome proliferators. Endogenous activation of PPARalpha in liver has also been observed in certain gene knockout mouse models of lipid metabolism, implying the existence of enzymes that either generate (synthesize) or degrade endogenous PPARalpha agonists. For example, substrates involved in fatty acid oxidation can function as PPARalpha ligands. PPARalpha serves as a xenobiotic and lipid sensor to regulate energy combustion, hepatic steatosis, lipoprotein synthesis, inflammation and liver cancer. Mainly, PPARalpha modulates the activities of all three fatty acid oxidation systems, namely mitochondrial and peroxisomal beta-oxidation and microsomal omega-oxidation, and thus plays a key role in energy expenditure. Sustained activation of PPARalpha by either exogenous or endogenous agonists leads to the development of hepatocellular carcinoma resulting from sustained oxidative and possibly endoplasmic reticulum stress and liver cell proliferation. PPARalpha requires transcription coactivator PPAR-binding protein (PBP)/mediator subunit 1(MED1) for its transcriptional activity.
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Affiliation(s)
| | | | | | - Janardan K. Reddy
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
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