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Desmarini D, Liu G, Jessen H, Bowring B, Connolly A, Crossett B, Djordjevic JT. Arg1 from Cryptococcus neoformans lacks PI3 kinase activity and conveys virulence roles via its IP 3-4 kinase activity. mBio 2024; 15:e0060824. [PMID: 38742909 PMCID: PMC11237472 DOI: 10.1128/mbio.00608-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 04/18/2024] [Indexed: 05/16/2024] Open
Abstract
Inositol tris/tetrakis phosphate kinases (IP3-4K) in the human fungal priority pathogens, Cryptococcus neoformans (CnArg1) and Candida albicans (CaIpk2), convey numerous virulence functions, yet it is not known whether the IP3-4K catalytic activity or a scaffolding role is responsible. We therefore generated a C. neoformans strain with a non-functional kinase, referred to as the dead-kinase (dk) CnArg1 strain (dkArg1). We verified that, although dkARG1 cDNA cloned from this strain produced a protein with the expected molecular weight, dkArg1 was catalytically inactive with no IP3-4K activity. Using recombinant CnArg1 and CaIpk2, we confirmed that, unlike the IP3-4K homologs in humans and Saccharomyces cerevisiae, CnArg1 and CaIpk2 do not phosphorylate the lipid-based substrate, phosphatidylinositol 4,5-bisphosphate, and therefore do not function as class I PI3Ks. Inositol polyphosphate profiling using capillary electrophoresis-electrospray ionization-mass spectrometry revealed that IP3 conversion is blocked in the dkArg1 and ARG1 deletion (Cnarg1Δ) strains and that 1-IP7 and a recently discovered isomer (4/6-IP7) are made by wild-type C. neoformans. Importantly, the dkArg1 and Cnarg1Δ strains had similar virulence defects, including suppressed growth at 37°C, melanization, capsule production, and phosphate starvation response, and were avirulent in an insect model, confirming that virulence is dependent on IP3-4K catalytic activity. Our data also implicate the dkArg1 scaffold in transcriptional regulation of arginine metabolism but via a different mechanism to S. cerevisiae since CnArg1 is dispensable for growth on different nitrogen sources. IP3-4K catalytic activity therefore plays a dominant role in fungal virulence, and IPK pathway function has diverged in fungal pathogens.IMPORTANCEThe World Health Organization has emphasized the urgent need for global action in tackling the high morbidity and mortality rates stemming from invasive fungal infections, which are exacerbated by the limited variety and compromised effectiveness of available drug classes. Fungal IP3-4K is a promising target for new therapy, as it is critical for promoting virulence of the human fungal priority pathogens, Cryptococcus neoformans and Candida albicans, and impacts numerous functions, including cell wall integrity. This contrasts to current therapies, which only target a single function. IP3-4K enzymes exert their effect through their inositol polyphosphate products or via the protein scaffold. Here, we confirm that the IP3-4K catalytic activity of CnArg1 promotes all virulence traits in C. neoformans that are attenuated by ARG1 deletion, reinforcing our ongoing efforts to find inositol polyphosphate effector proteins and to create inhibitors targeting the IP3-4K catalytic site, as a new antifungal drug class.
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Affiliation(s)
- Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, Australia
- Faculty of Medicine and Health, Sydney Institute for Infectious Diseases, University of Sydney, Sydney, Australia
| | - Guizhen Liu
- Institute of Organic Chemistry, University of Freiburg, Freiburg im Breisgau, Germany
- Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Henning Jessen
- Institute of Organic Chemistry, University of Freiburg, Freiburg im Breisgau, Germany
- Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Bethany Bowring
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, Australia
- Faculty of Medicine and Health, Sydney Institute for Infectious Diseases, University of Sydney, Sydney, Australia
| | - Angela Connolly
- Sydney Mass Spectrometry, University of Sydney, Sydney, Australia
| | - Ben Crossett
- Sydney Mass Spectrometry, University of Sydney, Sydney, Australia
| | - Julianne Teresa Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, Sydney, Australia
- Faculty of Medicine and Health, Sydney Institute for Infectious Diseases, University of Sydney, Sydney, Australia
- Westmead Hospital, Western Sydney Local Health District, Sydney, Australia
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2
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Sowd GA, Stivison EA, Chapagain P, Hale AT, Poland JC, Rameh LE, Blind RD. IPMK regulates HDAC3 activity and histone H4 acetylation in human cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.29.591660. [PMID: 38746349 PMCID: PMC11092501 DOI: 10.1101/2024.04.29.591660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Histone deacetylases (HDACs) repress transcription by catalyzing the removal of acetyl groups from histones. Class 1 HDACs are activated by inositol phosphate signaling molecules in vitro , but it is unclear if this regulation occurs in human cells. Inositol Polyphosphate Multikinase (IPMK) is required for production of inositol hexakisphosphate (IP6), pentakisphosphate (IP5) and certain tetrakisphosphate (IP4) species, all known activators of Class 1 HDACs in vitro . Here, we generated IPMK knockout (IKO) human U251 glioblastoma cells, which decreased cellular inositol phosphate levels and increased histone H4-acetylation by mass spectrometry. ChIP-seq showed IKO increased H4-acetylation at IKO-upregulated genes, but H4-acetylation was unchanged at IKO-downregulated genes, suggesting gene-specific responses to IPMK knockout. HDAC deacetylase enzyme activity was decreased in HDAC3 immunoprecipitates from IKO vs . wild-type cells, while deacetylase activity of other Class 1 HDACs had no detectable changes in activity. Wild-type IPMK expression in IKO cells fully rescued HDAC3 deacetylase activity, while kinase-dead IPMK expression had no effect. Further, the deficiency in HDAC3 activity in immunoprecipitates from IKO cells could be fully rescued by addition of synthesized IP4 (Ins(1,4,5,6)P4) to the enzyme assay, while control inositol had no effect. These data suggest that cellular IPMK-dependent inositol phosphates are required for full HDAC3 enzyme activity and proper histone H4-acetylation. Implications for targeting IPMK in HDAC3-dependent diseases are discussed.
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Pavlović N, Milošević Sopta N, Mitrović D, Zaklan D, Tomas Petrović A, Stilinović N, Vukmirović S. Principal Component Analysis (PCA) of Molecular Descriptors for Improving Permeation through the Blood-Brain Barrier of Quercetin Analogues. Int J Mol Sci 2023; 25:192. [PMID: 38203364 PMCID: PMC10778702 DOI: 10.3390/ijms25010192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/13/2023] [Accepted: 12/17/2023] [Indexed: 01/12/2024] Open
Abstract
Despite its beneficial pharmacological effects in the brain, partly by modulating inositol phosphate multikinase (IPMK) activity, the therapeutic use of quercetin is limited due to its poor solubility, low oral bioavailability, and low permeability through the blood-brain barrier (BBB). We aimed to identify quercetin analogues with improved BBB permeability and preserved binding affinities towards IPMK and to identify the molecular characteristics required for them to permeate the BBB. Binding affinities of quercetin analogues towards IPMK were determined by molecular docking. Principal component analysis (PCA) was applied to identify the molecular descriptors contributing to efficient permeation through the BBB. Among 34 quercetin analogues, 19 compounds were found to form more stable complexes with IPMK, and the vast majority were found to be more lipophilic than quercetin. Using two distinct in silico techniques, insufficient BBB permeation was determined for all quercetin analogues. However, using the PCA method, the descriptors related to intrinsic solubility and lipophilicity (logP) were identified as mainly responsible for clustering four quercetin analogues (trihydroxyflavones) with the highest BBB permeability. The application of PCA revealed that quercetin analogues could be classified with respect to their structural characteristics, which may be utilized in further analogue syntheses and lead optimization of BBB-penetrating IPMK modulators as neuroprotective agents.
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Affiliation(s)
- Nebojša Pavlović
- Department of Pharmacy, Faculty of Medicine, University of Novi Sad, Hajduk Veljkova 3, 21000 Novi Sad, Serbia; (D.M.); (D.Z.)
| | | | - Darko Mitrović
- Department of Pharmacy, Faculty of Medicine, University of Novi Sad, Hajduk Veljkova 3, 21000 Novi Sad, Serbia; (D.M.); (D.Z.)
- Accelsiors CRO, Háros Street 103, 1222 Budapest, Hungary;
| | - Dragana Zaklan
- Department of Pharmacy, Faculty of Medicine, University of Novi Sad, Hajduk Veljkova 3, 21000 Novi Sad, Serbia; (D.M.); (D.Z.)
| | - Ana Tomas Petrović
- Department of Pharmacology, Toxicology and Clinical Pharmacology, Faculty of Medicine, University of Novi Sad, Hajduk Veljkova 3, 21000 Novi Sad, Serbia; (A.T.P.); (N.S.); (S.V.)
| | - Nebojša Stilinović
- Department of Pharmacology, Toxicology and Clinical Pharmacology, Faculty of Medicine, University of Novi Sad, Hajduk Veljkova 3, 21000 Novi Sad, Serbia; (A.T.P.); (N.S.); (S.V.)
| | - Saša Vukmirović
- Department of Pharmacology, Toxicology and Clinical Pharmacology, Faculty of Medicine, University of Novi Sad, Hajduk Veljkova 3, 21000 Novi Sad, Serbia; (A.T.P.); (N.S.); (S.V.)
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Yu J, Leibiger B, Yang SN, Shears SB, Leibiger IB, Berggren PO, Barker CJ. Multiple Inositol Polyphosphate Phosphatase Compartmentalization Separates Inositol Phosphate Metabolism from Inositol Lipid Signaling. Biomolecules 2023; 13:885. [PMID: 37371464 DOI: 10.3390/biom13060885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 06/29/2023] Open
Abstract
Multiple inositol polyphosphate phosphatase (MINPP1) is an enigmatic enzyme that is responsible for the metabolism of inositol hexakisphosphate (InsP6) and inositol 1,3,4,5,6 pentakisphosphate (Ins(1,3,4,5,6)P5 in mammalian cells, despite being restricted to the confines of the ER. The reason for this compartmentalization is unclear. In our previous studies in the insulin-secreting HIT cell line, we expressed MINPP1 in the cytosol to artificially reduce the concentration of these higher inositol phosphates. Undocumented at the time, we noted cytosolic MINPP1 expression reduced cell growth. We were struck by the similarities in substrate preference between a number of different enzymes that are able to metabolize both inositol phosphates and lipids, notably IPMK and PTEN. MINPP1 was first characterized as a phosphatase that could remove the 3-phosphate from inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4). This molecule shares strong structural homology with the major product of the growth-promoting Phosphatidyl 3-kinase (PI3K), phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) and PTEN can degrade both this lipid and Ins(1,3,4,5)P4. Because of this similar substrate preference, we postulated that the cytosolic version of MINPP1 (cyt-MINPP1) may not only attack inositol polyphosphates but also PtdIns(3,4,5)P3, a key signal in mitogenesis. Our experiments show that expression of cyt-MINPP1 in HIT cells lowers the concentration of PtdIns(3,4,5)P3. We conclude this reflects a direct effect of MINPP1 upon the lipid because cyt-MINPP1 actively dephosphorylates synthetic, di(C4:0)PtdIns(3,4,5)P3 in vitro. These data illustrate the importance of MINPP1's confinement to the ER whereby important aspects of inositol phosphate metabolism and inositol lipid signaling can be separately regulated and give one important clarification for MINPP1's ER seclusion.
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Affiliation(s)
- Jia Yu
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Shao-Nian Yang
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Stephen B Shears
- Inositol Signaling Section, NIEHS, 111, Alexander Drive, Research Triangle Park, Durham, NC 27709, USA
| | - Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Christopher J Barker
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
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Tu CL, Chang W, Sosa JA, Koh J. Digital spatial profiling of human parathyroid tumors reveals cellular and molecular alterations linked to vitamin D deficiency. PNAS NEXUS 2023; 2:pgad073. [PMID: 36992820 PMCID: PMC10042281 DOI: 10.1093/pnasnexus/pgad073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 02/22/2023] [Accepted: 03/02/2023] [Indexed: 03/12/2023]
Abstract
Primary hyperparathyroidism (PHPT) is a common endocrine neoplastic disorder characterized by disrupted calcium homeostasis secondary to inappropriately elevated parathyroid hormone (PTH) secretion. Low levels of serum 25-hydroxyvitamin D (25OHD) are significantly more prevalent in PHPT patients than in the general population (1-3), but the basis for this association remains unclear. We employed a spatially defined in situ whole-transcriptomics and selective proteomics profiling approach to compare gene expression patterns and cellular composition in parathyroid adenomas from vitamin D-deficient or vitamin D-replete PHPT patients. A cross-sectional panel of eucalcemic cadaveric donor parathyroid glands was examined in parallel as normal tissue controls. Here, we report that parathyroid tumors from vitamin D-deficient PHPT patients (Def-Ts) are intrinsically different from those of vitamin D-replete patients (Rep-Ts) of similar age and preoperative clinical presentation. The parathyroid oxyphil cell content is markedly higher in Def-Ts (47.8%) relative to Rep-Ts (17.8%) and normal donor glands (7.7%). Vitamin D deficiency is associated with increased expression of electron transport chain and oxidative phosphorylation pathway components. Parathyroid oxyphil cells, while morphologically distinct, are comparable to chief cells at the transcriptional level, and vitamin D deficiency affects the transcriptional profiles of both cell types in a similar manner. These data suggest that oxyphil cells are derived from chief cells and imply that their increased abundance may be induced by low vitamin D status. Gene set enrichment analysis reveals that pathways altered in Def-Ts are distinct from Rep-Ts, suggesting alternative tumor etiologies in these groups. Increased oxyphil content may thus be a morphological indicator of tumor-predisposing cellular stress.
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Affiliation(s)
- Chia-Ling Tu
- Endocrine Research Unit, Department of Medicine, San Francisco Department of Veterans Affairs Medical Center, University of California San Francisco, San Francisco, CA 94158
| | - Wenhan Chang
- Endocrine Research Unit, Department of Medicine, San Francisco Department of Veterans Affairs Medical Center, University of California San Francisco, San Francisco, CA 94158
| | - Julie A Sosa
- Endocrine Neoplasia Laboratory, Department of Surgery, University of California San Francisco, San Francisco, CA 94143
| | - James Koh
- Endocrine Neoplasia Laboratory, Department of Surgery, University of California San Francisco, San Francisco, CA 94143
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miRNA-Induced Downregulation of IPMK in Macrophages Mediates Lipopolysaccharide-Triggered TLR4 Signaling. Biomolecules 2023; 13:biom13020332. [PMID: 36830701 PMCID: PMC9952907 DOI: 10.3390/biom13020332] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 01/27/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Inositol polyphosphate multikinase (IPMK) is a pleiotropic enzyme responsible for the production of inositol polyphosphates and phosphoinositide. IPMK in macrophages was identified as a key factor for the full activation of the Toll-like receptor 4 (TLR4) signaling pathway and inflammation by directly interacting with tumor necrosis factor receptor-associated factor 6 (TRAF6). Here, dynamic changes of IPMK levels in lipopolysaccharide (LPS)-stimulated macrophages and their functional significance were investigated. Both the mRNA and protein levels of IPMK were acutely decreased in mouse and human macrophages when cells were stimulated with LPS for between 1 and 6 h. Analysis of the 3' untranslated region (UTR) of mouse IPMK mRNA revealed a highly conserved binding site for miR-181c. Transfection of miR-181c mimics into RAW 264.7 macrophages led to decreased IPMK 3'UTR-luciferase reporter activity and lowered endogenous IPMK levels. When the genomic deletion of a 33-bp fragment containing a putative miR-181c-binding site was introduced within the IPMK 3'UTR of RAW 264.7 macrophages (264.7Δ3'UTR), LPS-triggered downregulation of IPMK levels was prevented. LPS treatment in 264.7Δ3'UTR macrophages decreased TLR4-induced signaling and the expression of proinflammatory cytokines. In response to LPS stimulation, K63-linked ubiquitination of TRAF6 was impaired in 264.7Δ3'UTR macrophages, suggesting an action of IPMK in the suppression of TRAF6 activation. Therefore, our findings reveal that LPS-mediated suppression of IPMK regulates the full activation of TLR4 signaling and inflammation in macrophages.
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7
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Gut Epithelial Inositol Polyphosphate Multikinase Alleviates Experimental Colitis via Governing Tuft Cell Homeostasis. Cell Mol Gastroenterol Hepatol 2022; 14:1235-1256. [PMID: 35988719 PMCID: PMC9579329 DOI: 10.1016/j.jcmgh.2022.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/11/2022] [Accepted: 08/11/2022] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Inositol polyphosphate multikinase (IPMK), an essential enzyme for inositol phosphate metabolism, has been known to mediate major biological events such as growth. Recent studies have identified single-nucleotide polymorphisms in the IPMK gene associated with inflammatory bowel disease predisposition. Therefore, we aimed to investigate the functional significance of IPMK in gut epithelium. METHODS We generated intestinal epithelial cell (IEC)-specific Ipmk knockout (IPMKΔIEC) mice, and assessed their vulnerability against dextran sulfate sodium-induced experimental colitis. Both bulk and single-cell RNA sequencing were performed to analyze IPMK-deficient colonic epithelial cells and colonic tuft cells. RESULTS Although IPMKΔIEC mice developed normally and showed no intestinal abnormalities during homeostasis, Ipmk deletion aggravated dextran sulfate sodium-induced colitis, with higher clinical colitis scores, and increased epithelial barrier permeability. Surprisingly, Ipmk deletion led to a significant decrease in the number of tuft cells without influencing other IECs. Single-cell RNA sequencing of mouse colonic tuft cells showed 3 distinct populations of tuft cells, and further showed that a transcriptionally inactive population was expanded markedly in IPMKΔIEC mice, while neuronal-related cells were relatively decreased. CONCLUSIONS Cholinergic output from tuft cells is known to be critical for the restoration of intestinal architecture upon damage, supporting that tuft cell-defective IPMKΔIEC mice are more prone to colitis. Thus, intestinal epithelial IPMK is a critical regulator of colonic integrity and tissue regeneration by determining tuft cell homeostasis and affecting cholinergic output.
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8
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Wang YH, Sheetz MP. When PIP2 Meets p53: Nuclear Phosphoinositide Signaling in the DNA Damage Response. Front Cell Dev Biol 2022; 10:903994. [PMID: 35646908 PMCID: PMC9136457 DOI: 10.3389/fcell.2022.903994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
The mechanisms that maintain genome stability are critical for preventing tumor progression. In the past decades, many strategies were developed for cancer treatment to disrupt the DNA repair machinery or alter repair pathway selection. Evidence indicates that alterations in nuclear phosphoinositide lipids occur rapidly in response to genotoxic stresses. This implies that nuclear phosphoinositides are an upstream element involved in DNA damage signaling. Phosphoinositides constitute a new signaling interface for DNA repair pathway selection and hence a new opportunity for developing cancer treatment strategies. However, our understanding of the underlying mechanisms by which nuclear phosphoinositides regulate DNA damage repair, and particularly the dynamics of those processes, is rather limited. This is partly because there are a limited number of techniques that can monitor changes in the location and/or abundance of nuclear phosphoinositide lipids in real time and in live cells. This review summarizes our current knowledge regarding the roles of nuclear phosphoinositides in DNA damage response with an emphasis on the dynamics of these processes. Based upon recent findings, there is a novel model for p53’s role with nuclear phosphoinositides in DNA damage response that provides new targets for synthetic lethality of tumors.
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Beon J, Han S, Yang H, Park SE, Hyun K, Lee SY, Rhee HW, Seo JK, Kim J, Kim S, Lee D. Inositol polyphosphate multikinase physically binds to the SWI/SNF complex and modulates BRG1 occupancy in mouse embryonic stem cells. eLife 2022; 11:73523. [PMID: 35551737 PMCID: PMC9098221 DOI: 10.7554/elife.73523] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Inositol polyphosphate multikinase (IPMK), a key enzyme in inositol polyphosphate (IP) metabolism, is a pleiotropic signaling factor involved in major biological events, including transcriptional control. In the yeast, IPMK and its IP products promote the activity of the chromatin remodeling complex SWI/SNF, which plays a critical role in gene expression by regulating chromatin accessibility. However, the direct link between IPMK and chromatin remodelers remains unclear, raising the question of how IPMK contributes to transcriptional regulation in mammals. By employing unbiased screening approaches and in vivo/in vitro immunoprecipitation, here we demonstrate that mammalian IPMK physically interacts with the SWI/SNF complex by directly binding to SMARCB1, BRG1, and SMARCC1. Furthermore, we identified the specific domains required for IPMK-SMARCB1 binding. Notably, using CUT&RUN and ATAC-seq assays, we discovered that IPMK co-localizes with BRG1 and regulates BRG1 localization as well as BRG1-mediated chromatin accessibility in a genome-wide manner in mouse embryonic stem cells. Together, these findings show that IPMK regulates the promoter targeting of the SWI/SNF complex, thereby contributing to SWI/SNF-meditated chromatin accessibility, transcription, and differentiation in mouse embryonic stem cells.
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Affiliation(s)
- Jiyoon Beon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Sungwook Han
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Hyeokjun Yang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Seung Eun Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Kwangbeom Hyun
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.,Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Song-Yi Lee
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Hyun-Woo Rhee
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Jeong Kon Seo
- UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Jaehoon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Seyun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.,KAIST Stem Cell Center, KAIST, Daejeon, Republic of Korea.,KAIST Institute for the BioCentury, KAIST, Daejeon, Republic of Korea
| | - Daeyoup Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
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Ricaña CL, Dick RA. Inositol Phosphates and Retroviral Assembly: A Cellular Perspective. Viruses 2021; 13:v13122516. [PMID: 34960784 PMCID: PMC8703376 DOI: 10.3390/v13122516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/09/2021] [Accepted: 12/11/2021] [Indexed: 12/13/2022] Open
Abstract
Understanding the molecular mechanisms of retroviral assembly has been a decades-long endeavor. With the recent discovery of inositol hexakisphosphate (IP6) acting as an assembly co-factor for human immunodeficiency virus (HIV), great strides have been made in retroviral research. In this review, the enzymatic pathways to synthesize and metabolize inositol phosphates (IPs) relevant to retroviral assembly are discussed. The functions of these enzymes and IPs are outlined in the context of the cellular biology important for retroviruses. Lastly, the recent advances in understanding the role of IPs in retroviral biology are surveyed.
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Lee B, Park SJ, Hong S, Kim K, Kim S. Inositol Polyphosphate Multikinase Signaling: Multifaceted Functions in Health and Disease. Mol Cells 2021; 44:187-194. [PMID: 33935040 PMCID: PMC8112168 DOI: 10.14348/molcells.2021.0045] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/14/2021] [Accepted: 04/15/2021] [Indexed: 12/19/2022] Open
Abstract
Inositol phosphates are water-soluble intracellular signaling molecules found in eukaryotes from yeasts to mammals, which are synthesized by a complex network of enzymes including inositol phosphate kinases. Among these, inositol polyphosphate multikinase (IPMK) is a promiscuous enzyme with broad substrate specificity, which phosphorylates multiple inositol phosphates, as well as phosphatidylinositol 4,5-bisphosphate. In addition to its catalytic actions, IPMK is known to non-catalytically control major signaling events via direct protein-protein interactions. In this review, we describe the general characteristics of IPMK, highlight its pleiotropic roles in various physiological and pathological conditions, and discuss future challenges in the field of IPMK signaling pathways.
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Affiliation(s)
- Boah Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Seung Ju Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Sehoon Hong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Kyunghan Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Seyun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
- KAIST Institute for the BioCentury, KAIST, Daejeon 34141, Korea
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Chen D, Wang Z, Zhao YG, Zheng H, Zhao H, Liu N, Zhang H. Inositol Polyphosphate Multikinase Inhibits Liquid-Liquid Phase Separation of TFEB to Negatively Regulate Autophagy Activity. Dev Cell 2021; 55:588-602.e7. [PMID: 33290695 DOI: 10.1016/j.devcel.2020.10.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 08/03/2020] [Accepted: 10/14/2020] [Indexed: 01/26/2023]
Abstract
Liquid-liquid phase separation (LLPS) compartmentalizes transcriptional condensates for gene expression, but little is known about how this process is controlled. Here, we showed that depletion of IPMK, encoding inositol polyphosphate multikinase, promotes autophagy and lysosomal function and biogenesis in a TFEB-dependent manner. Cytoplasmic-nuclear trafficking of TFEB, a well-characterized mechanism by which diverse signaling pathways regulate TFEB activity, is not evidently altered by IPMK depletion. We demonstrated that nuclear TFEB forms distinct puncta that colocalize with the Mediator complex and with mRNAs of target lysosomal genes. TFEB undergoes LLPS in vitro. IPMK directly interacts with and inhibits LLPS of TFEB and also dissolves TFEB condensates. Depletion of IPMK increases the number of nuclear TFEB puncta and the co-localization of TFEB with Mediator and mRNAs of target genes. Our study reveals that nuclear-localized IPMK acts as a chaperone to inhibit LLPS of TFEB to negatively control its transcriptional activity.
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Affiliation(s)
- Di Chen
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P.R. China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Zheng Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Yan G Zhao
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Hui Zheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Hongyu Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Nan Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P.R. China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, P.R. China.
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13
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Dato S, Crocco P, De Rango F, Iannone F, Maletta R, Bruni AC, Saiardi A, Rose G, Passarino G. IP6K3 and IPMK variations in LOAD and longevity: Evidence for a multifaceted signaling network at the crossroad between neurodegeneration and survival. Mech Ageing Dev 2021; 195:111439. [PMID: 33497757 DOI: 10.1016/j.mad.2021.111439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/23/2020] [Accepted: 01/18/2021] [Indexed: 12/18/2022]
Abstract
Several studies reported that genetic variants predisposing to neurodegeneration were at higher frequencies in centenarians than in younger controls, suggesting they might favor also longevity. IP6K3 and IPMK regulate many crucial biological functions by mediating synthesis of inositol poly- and pyrophosphates and by acting non-enzymatically via protein-protein interactions. Our previous studies suggested they affect Late Onset Alzheimer Disease (LOAD) and longevity, respectively. Here, in the same sample groups, we investigated whether variants of IP6K3 also affect longevity, and variants of IPMK also influence LOAD susceptibility. We found that: i) a SNP of IP6K3 previously associated with increased risk of LOAD increased the chance to become long-lived, ii) SNPs of IPMK, previously associated with decreased longevity, were protective factors for LOAD, as previously observed for UCP4. SNP-SNP interaction analysis, including our previous data, highlighted phenotype-specific interactions between sets of alleles. Moreover, linkage disequilibrium and eQTL data associated to analyzed variants suggested mitochondria as crossroad of interconnected pathways crucial for susceptibility to neurodegeneration and/or longevity. Overall, data support the view that in these traits interactions may be more important than single polymorphisms. This phenomenon may contribute to the non-additive heritability of neurodegeneration and longevity and be part of the missing heritability of these traits.
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Affiliation(s)
- Serena Dato
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy.
| | - Paolina Crocco
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy.
| | - Francesco De Rango
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy.
| | - Francesca Iannone
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy.
| | - Raffaele Maletta
- Regional Neurogenetic Centre, ASP Catanzaro, Lamezia Terme, Italy.
| | - Amalia C Bruni
- Regional Neurogenetic Centre, ASP Catanzaro, Lamezia Terme, Italy.
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK.
| | - Giuseppina Rose
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy.
| | - Giuseppe Passarino
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Rende, Italy.
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14
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Inositol phosphates promote HIV-1 assembly and maturation to facilitate viral spread in human CD4+ T cells. PLoS Pathog 2021; 17:e1009190. [PMID: 33476323 PMCID: PMC7853515 DOI: 10.1371/journal.ppat.1009190] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 02/02/2021] [Accepted: 11/26/2020] [Indexed: 11/19/2022] Open
Abstract
Gag polymerization with viral RNA at the plasma membrane initiates HIV-1 assembly. Assembly processes are inefficient in vitro but are stimulated by inositol (1,3,4,5,6) pentakisphosphate (IP5) and inositol hexakisphosphate (IP6) metabolites. Previous studies have shown that depletion of these inositol phosphate species from HEK293T cells reduced HIV-1 particle production but did not alter the infectivity of the resulting progeny virions. Moreover, HIV-1 substitutions bearing Gag/CA mutations ablating IP6 binding are noninfectious with destabilized viral cores. In this study, we analyzed the effects of cellular depletion of IP5 and IP6 on HIV-1 replication in T cells in which we disrupted the genes encoding the kinases required for IP6 generation, IP5 2-kinase (IPPK) and Inositol Polyphosphate Multikinase (IPMK). Knockout (KO) of IPPK from CEM and MT-4 cells depleted cellular IP6 in both T cell lines, and IPMK disruption reduced the levels of both IP5 and IP6. In the KO lines, HIV-1 spread was delayed relative to parental wild-type (WT) cells and was rescued by complementation. Virus release was decreased in all IPPK or IPMK KO lines relative to WT cells. Infected IPMK KO cells exhibited elevated levels of intracellular Gag protein, indicative of impaired particle assembly. IPMK KO compromised virus production to a greater extent than IPPK KO suggesting that IP5 promotes HIV-1 particle assembly in IPPK KO cells. HIV-1 particles released from infected IPPK or IPMK KO cells were less infectious than those from WT cells. These viruses exhibited partially cleaved Gag proteins, decreased virion-associated p24, and higher frequencies of aberrant particles, indicative of a maturation defect. Our data demonstrate that IP6 enhances the quantity and quality of virions produced from T cells, thereby preventing defects in HIV-1 replication.
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Damstra-Oddy JL, Warren EC, Perry CJ, Desfougères Y, Fitzpatrick JMK, Schaf J, Costelloe L, Hind W, Downer EJ, Saiardi A, Williams RSB. Phytocannabinoid-dependent mTORC1 regulation is dependent upon inositol polyphosphate multikinase activity. Br J Pharmacol 2021; 178:1149-1163. [PMID: 33347604 PMCID: PMC9328663 DOI: 10.1111/bph.15351] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Cannabidiol (CBD) has been shown to differentially regulate the mechanistic target of rapamycin complex 1 (mTORC1) in preclinical models of disease, where it reduces activity in models of epilepsies and cancer and increases it in models of multiple sclerosis (MS) and psychosis. Here, we investigate the effects of phytocannabinoids on mTORC1 and define a molecular mechanism. EXPERIMENTAL APPROACH A novel mechanism for phytocannabinoids was identified using the tractable model system, Dictyostelium discoideum. Using mouse embryonic fibroblasts, we further validate this new mechanism of action. We demonstrate clinical relevance using cells derived from healthy individuals and from people with MS (pwMS). KEY RESULTS Both CBD and the more abundant cannabigerol (CBG) enhance mTORC1 activity in D. discoideum. We identify a mechanism for this effect involving inositol polyphosphate multikinase (IPMK), where elevated IPMK expression reverses the response to phytocannabinoids, decreasing mTORC1 activity upon treatment, providing new insight on phytocannabinoids' actions. We further validated this mechanism using mouse embryonic fibroblasts. Clinical relevance of this effect was shown in primary human peripheral blood mononuclear cells, where CBD and CBG treatment increased mTORC1 activity in cells derived from healthy individuals and decreased mTORC1 activity in cells derived from pwMS. CONCLUSION AND IMPLICATIONS Our findings suggest that both CBD and the abundant CBG differentially regulate mTORC1 signalling through a mechanism dependent on the activity of the upstream IPMK signalling pathway, with potential relevance to the treatment of mTOR-related disorders, including MS.
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Affiliation(s)
- Joseph L Damstra-Oddy
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Eleanor C Warren
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Christopher J Perry
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Yann Desfougères
- Laboratory for Molecular Cell Biology, University College London, London, UK
| | - John-Mark K Fitzpatrick
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Judith Schaf
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
| | - Lisa Costelloe
- Department of Neurology, Beaumont Hospital, Dublin, Ireland
| | | | - Eric J Downer
- Discipline of Physiology, School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Adolfo Saiardi
- Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Robin S B Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
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16
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Yang ZL, Chen JN, Lu YY, Lu M, Wan QL, Wu GS, Luo HR. Inositol polyphosphate multikinase IPMK-1 regulates development through IP3/calcium signaling in Caenorhabditis elegans. Cell Calcium 2020; 93:102327. [PMID: 33316585 DOI: 10.1016/j.ceca.2020.102327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/25/2020] [Accepted: 11/27/2020] [Indexed: 01/17/2023]
Abstract
Inositol polyphosphate multikinase (IPMK) is a conserved protein that initiates the production of inositol phosphate intracellular messengers and is critical for regulating a variety of cellular processes. Here, we report that the C. elegans IPMK-1, which is homologous to the mammalian inositol polyphosphate multikinase, plays a crucial role in regulating rhythmic behavior and development. The deletion mutant ipmk-1(tm2687) displays a long defecation cycle period and retarded postembryonic growth. The expression of functional ipmk-1::GFP was detected in the pharyngeal muscles, amphid sheath cells, the intestine, excretory (canal) cells, proximal gonad, and spermatheca. The expression of IPMK-1 in the intestine was sufficient for the wild-type phenotype. The IP3-kinase activity of IPMK-1 is required for defecation rhythms and postembryonic development. The defective phenotypes of ipmk-1(tm2687) could be rescued by a loss-of-function mutation in type I inositol 5-phosphatase homolog (IPP-5) and improved by a supplemental Ca2+ in the medium. Our work demonstrates that IPMK-1 and the signaling molecule inositol triphosphate (IP3) pathway modulate rhythmic behaviors and development by dynamically regulating the concentration of intracellular Ca2+ in C. elegans. Advances in understanding the molecular regulation of Ca2+ homeostasis and regulation of organism development may lead to therapeutic strategies that modulate Ca2+ signaling to enhance function and counteract disease processes. Unraveling the physiological role of IPMK and the underlying functional mechanism in C. elegans would contribute to understanding the role of IPMK in other species, especially in mammals, and benefit further research on the involvement of IPMK in disease.
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Affiliation(s)
- Zhong-Lin Yang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Graduate University of the Chinese Academy of Science, Beijing, 100049, China
| | - Jian-Ning Chen
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Yu-Yang Lu
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Min Lu
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Qin-Li Wan
- The Center for Precision Medicine of First Affiliated Hospital, Biomedical Translational Research Institute, Jinan University, Guangzhou, Guangdong 510632, China
| | - Gui-Sheng Wu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
| | - Huai-Rong Luo
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Graduate University of the Chinese Academy of Science, Beijing, 100049, China; Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
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17
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Ricana CL, Lyddon TD, Dick RA, Johnson MC. Primate lentiviruses require Inositol hexakisphosphate (IP6) or inositol pentakisphosphate (IP5) for the production of viral particles. PLoS Pathog 2020; 16:e1008646. [PMID: 32776974 PMCID: PMC7446826 DOI: 10.1371/journal.ppat.1008646] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/20/2020] [Accepted: 06/26/2020] [Indexed: 11/18/2022] Open
Abstract
Inositol hexakisphosphate (IP6) potently stimulates HIV-1 particle assembly in vitro and infectious particle production in vivo. However, knockout cells lacking inositol-pentakisphosphate 2-kinase (IPPK-KO), the enzyme that produces IP6 by phosphorylation of inositol pentakisphosphate (IP5), were still able to produce infectious HIV-1 particles at a greatly reduced rate. HIV-1 in vitro assembly can also be stimulated to a lesser extent with IP5, but until recently, it was not known if IP5 could also function in promoting assembly in vivo. Here we addressed whether there is an absolute requirement for IP6 or IP5 in the production of infectious HIV-1 particles. IPPK-KO cells expressed no detectable IP6 but elevated IP5 levels and displayed a 20-100-fold reduction in infectious particle production, correlating with lost virus release. Transient transfection of an IPPK expression vector stimulated infectious particle production and release in IPPK-KO but not wildtype cells. Several attempts to make IP6/IP5 deficient stable cells were not successful, but transient expression of the enzyme multiple inositol polyphosphate phosphatase-1 (MINPP1) into IPPK-KOs resulted in near ablation of IP6 and IP5. Under these conditions, we found that HIV-1 infectious particle production and virus release were essentially abolished (1000-fold reduction) demonstrating an IP6/IP5 requirement. However, other retroviruses including a Gammaretrovirus, a Betaretrovirus, and two non-primate Lentiviruses displayed only a modest (3-fold) reduction in infectious particle production from IPPK-KOs and were not significantly altered by expression of IPPK or MINPP1. The only other retrovirus found to show a clear IP6/IP5 dependence was the primate (macaque) Lentivirus Simian Immunodeficiency Virus, which displayed similar sensitivity as HIV-1. We were not able to determine if producer cell IP6/IP5 is required at additional steps beyond assembly because viral particles devoid of both molecules could not be generated. Finally, we found that loss of IP6/IP5 in viral target cells had no effect on permissivity to HIV-1 infection.
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Affiliation(s)
- Clifton L Ricana
- Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Terri D Lyddon
- Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
| | - Robert A Dick
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Marc C Johnson
- Department of Molecular Microbiology and Immunology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America
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18
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Hwang SH, Bang S, Kim W, Chung J. Von Hippel-Lindau tumor suppressor (VHL) stimulates TOR signaling by interacting with phosphoinositide 3-kinase (PI3K). J Biol Chem 2020; 295:2336-2347. [PMID: 31959630 DOI: 10.1074/jbc.ra119.011596] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
Cell growth is positively controlled by the phosphoinositide 3-kinase (PI3K)-target of rapamycin (TOR) signaling pathway under conditions of abundant growth factors and nutrients. To discover additional mechanisms that regulate cell growth, here we performed RNAi-based mosaic analyses in the Drosophila fat body, the primary metabolic organ in the fly. Unexpectedly, the knockdown of the Drosophila von Hippel-Lindau (VHL) gene markedly decreased cell size and body size. These cell growth phenotypes induced by VHL loss of function were recovered by activation of TOR signaling in Drosophila Consistent with the genetic interactions between VHL and the signaling components of PI3K-TOR pathway in Drosophila, we observed that VHL loss of function in mammalian cells causes decreased phosphorylation of ribosomal protein S6 kinase and Akt, which represent the main activities of this pathway. We further demonstrate that VHL activates TOR signaling by directly interacting with the p110 catalytic subunit of PI3K. On the basis of the evolutionarily conserved regulation of PI3K-TOR signaling by VHL observed here, we propose that VHL plays an important role in the regulation and maintenance of proper cell growth in metazoans.
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Affiliation(s)
- Sun-Hong Hwang
- School of Biological Sciences, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea; Institute of Molecular Biology and Genetics, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Sunhoe Bang
- School of Biological Sciences, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea; Institute of Molecular Biology and Genetics, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Wonho Kim
- Institute of Molecular Biology and Genetics, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Jongkyeong Chung
- School of Biological Sciences, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea; Institute of Molecular Biology and Genetics, Seoul National University, Gwanak-Gu, Seoul 08826, Republic of Korea.
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Scott DD, Aguilar LC, Kramar M, Oeffinger M. It's Not the Destination, It's the Journey: Heterogeneity in mRNA Export Mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1203:33-81. [PMID: 31811630 DOI: 10.1007/978-3-030-31434-7_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The process of creating a translation-competent mRNA is highly complex and involves numerous steps including transcription, splicing, addition of modifications, and, finally, export to the cytoplasm. Historically, much of the research on regulation of gene expression at the level of the mRNA has been focused on either the regulation of mRNA synthesis (transcription and splicing) or metabolism (translation and degradation). However, in recent years, the advent of new experimental techniques has revealed the export of mRNA to be a major node in the regulation of gene expression, and numerous large-scale and specific mRNA export pathways have been defined. In this chapter, we will begin by outlining the mechanism by which most mRNAs are homeostatically exported ("bulk mRNA export"), involving the recruitment of the NXF1/TAP export receptor by the Aly/REF and THOC5 components of the TREX complex. We will then examine various mechanisms by which this pathway may be controlled, modified, or bypassed in order to promote the export of subset(s) of cellular mRNAs, which include the use of metazoan-specific orthologs of bulk mRNA export factors, specific cis RNA motifs which recruit mRNA export machinery via specific trans-acting-binding factors, posttranscriptional mRNA modifications that act as "inducible" export cis elements, the use of the atypical mRNA export receptor, CRM1, and the manipulation or bypass of the nuclear pore itself. Finally, we will discuss major outstanding questions in the field of mRNA export heterogeneity and outline how cutting-edge experimental techniques are providing new insights into and tools for investigating the intriguing field of mRNA export heterogeneity.
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Affiliation(s)
- Daniel D Scott
- Institut de recherches cliniques de Montréal, Montréal, QC, Canada.,Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | | | - Mathew Kramar
- Institut de recherches cliniques de Montréal, Montréal, QC, Canada.,Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | - Marlene Oeffinger
- Institut de recherches cliniques de Montréal, Montréal, QC, Canada. .,Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, QC, Canada. .,Faculté de Médecine, Département de Biochimie, Université de Montréal, Montréal, QC, Canada.
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20
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Structural analyses of inositol phosphate second messengers bound to signaling effector proteins. Adv Biol Regul 2019; 75:100667. [PMID: 31648945 DOI: 10.1016/j.jbior.2019.100667] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/17/2019] [Accepted: 09/30/2019] [Indexed: 01/02/2023]
Abstract
The higher-order inositol phosphate second messengers inositol tetrakisphosphate (IP4), inositol pentakisphosphate (IP5) and inositol hexakisphosphate (IP6) are important signaling molecules that regulate DNA-damage repair, cohesin dynamics, RNA-editing, retroviral assembly, nuclear transport, phosphorylation, acetylation, crotonylation, and ubiquitination. This functional diversity has made understanding how inositol polyphosphates regulate cellular processes challenging to dissect. However, some inositol phosphates have been unexpectedly found in X-ray crystal structures, occasionally revealing structural and mechanistic details of effector protein regulation before functional consequences have been described. This review highlights a sampling of crystal structures describing the interaction between inositol phosphates and protein effectors. This list includes the RNA editing enzyme "adenosine deaminase that acts on RNA 2" (ADAR2), the Pds5B regulator of cohesin dynamics, the class 1 histone deacetylases (HDACs) HDAC1 and HDAC3, and the PH domain of Bruton's tyrosine kinase (Btk). One of the most important enzymes responsible for higher-order inositol phosphate synthesis is inositol polyphosphate multikinase (IPMK), which plays dual roles in both inositol and phosphoinositide signaling. Structures of phosphoinositide lipid binding proteins have also revealed new aspects of protein effector regulation, as mediated by the nuclear receptors Steroidogenic Factor-1 (SF-1, NR5A2) and Liver Receptor Homolog-1 (LRH-1, NR5A2). Together, these studies underscore the structural diversity in binding interactions between effector proteins and inositol phosphate small signaling molecules, and further support that detailed structural studies can lead to new biological discovery.
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21
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Park J, Park SJ, Kim S. Inositol polyphosphate multikinase deficiency leads to aberrant induction of synaptotagmin-2 in the forebrain. Mol Brain 2019; 12:58. [PMID: 31221192 PMCID: PMC6584979 DOI: 10.1186/s13041-019-0480-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/13/2019] [Indexed: 12/30/2022] Open
Abstract
Inositol polyphosphate multikinase (IPMK), the key enzyme responsible for the synthesis of higher inositol polyphosphates and phosphatidylinositol 3, 4, 5-trisphosphate, is known to mediate various biological events, such as cellular growth and metabolism. Conditional deletion of IPMK in excitatory neurons of the mouse postnatal forebrain results in enhanced extinction of fear memory accompanied by activation of p85 S6 kinase 1 signaling in the amygdala; it also facilitates hippocampal long-term potentiation. However, the molecular changes triggered by IPMK deletion in the brain have not been fully elucidated. In the present study, we investigated gene expression changes in the hippocampal region of IPMK conditional knockout (cKO) mice by performing genome-wide transcriptome analyses. Here we show that expression of synaptotagmin 2 (Syt2), a synaptic vesicle protein essential for Ca2+-dependent neurotransmitter release, is robustly upregulated in the forebrain of IPMKcKO mice. Compared to wild-type mice, in which weak Syt2 expression was detected in the forebrain, IPMKcKO mice showed marked increases in both Syt2 mRNA and protein expression in the hippocampus as well as the amygdala. Collectively, our results suggest a physiological role for IPMK in regulating expression of Syt2, providing a potential underlying molecular mechanism to explain IPMK-mediated neural functions.
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Affiliation(s)
- Jina Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Seung Ju Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Seyun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea. .,KAIST Institute for the BioCentury, KAIST, Daejeon, 34141, South Korea.
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22
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Inositol polyphosphate multikinase mediates extinction of fear memory. Proc Natl Acad Sci U S A 2019; 116:2707-2712. [PMID: 30692248 DOI: 10.1073/pnas.1812771116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Inositol polyphosphate multikinase (IPMK), the key enzyme for the biosynthesis of higher inositol polyphosphates and phosphatidylinositol 3,4,5-trisphosphate, also acts as a versatile signaling player in regulating tissue growth and metabolism. To elucidate neurobehavioral functions of IPMK, we generated mice in which IPMK was deleted from the excitatory neurons of the postnatal forebrain. These mice showed no deficits in either novel object recognition or spatial memory. IPMK conditional knockout mice formed cued fear memory normally but displayed enhanced fear extinction. Signaling analyses revealed dysregulated expression of neural genes accompanied by selective activation of the mechanistic target of rapamycin (mTOR) regulatory enzyme p85 S6 kinase 1 (S6K1) in the amygdala following fear extinction. The IPMK mutants also manifested facilitated hippocampal long-term potentiation. These findings establish a signaling action of IPMK that mediates fear extinction.
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23
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Gu C, Stashko MA, Puhl-Rubio AC, Chakraborty M, Chakraborty A, Frye SV, Pearce KH, Wang X, Shears SB, Wang H. Inhibition of Inositol Polyphosphate Kinases by Quercetin and Related Flavonoids: A Structure-Activity Analysis. J Med Chem 2019; 62:1443-1454. [PMID: 30624931 DOI: 10.1021/acs.jmedchem.8b01593] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Dietary flavonoids inhibit certain protein kinases and phospholipid kinases by competing for their ATP-binding sites. These nucleotide pockets have structural elements that are well-conserved in two human small-molecule kinases, inositol hexakisphosphate kinase (IP6K) and inositol polyphosphate multikinase (IPMK), which synthesize multifunctional inositol phosphate cell signals. Herein, we demonstrate that both kinases are inhibited by quercetin and 16 related flavonoids; IP6K is the preferred target. Relative inhibitory activities were rationalized by X-ray analysis of kinase/flavonoid crystal structures; this detailed structure-activity analysis revealed hydrophobic and polar ligand/protein interactions, the degree of flexibility of key amino acid side chains, and the importance of water molecules. The seven most potent IP6K inhibitors were incubated with intact HCT116 cells at concentrations of 2.5 μM; diosmetin was the most selective and effective IP6K inhibitor (>70% reduction in activity). Our data can instruct on pharmacophore properties to assist the future development of inositol phosphate kinase inhibitors. Finally, we propose that dietary flavonoids may inhibit IP6K activity in cells that line the gastrointestinal tract.
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Affiliation(s)
- Chunfang Gu
- Inositol Signaling Group, Signal Transduction Laboratory , National Institute of Environmental Health Sciences , Research Triangle Park , North Carolina 27709 , United States
| | - Michael A Stashko
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Ana C Puhl-Rubio
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Molee Chakraborty
- Department of Pharmacology and Physiology , Saint Louis University School of Medicine , M370, Schwitalla Hall, 1402 South Grand Boulevard , Saint Louis , Missouri 63104 , United States
| | - Anutosh Chakraborty
- Department of Pharmacology and Physiology , Saint Louis University School of Medicine , M370, Schwitalla Hall, 1402 South Grand Boulevard , Saint Louis , Missouri 63104 , United States
| | - Stephen V Frye
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Kenneth H Pearce
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Xiaodong Wang
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Stephen B Shears
- Inositol Signaling Group, Signal Transduction Laboratory , National Institute of Environmental Health Sciences , Research Triangle Park , North Carolina 27709 , United States
| | - Huanchen Wang
- Inositol Signaling Group, Signal Transduction Laboratory , National Institute of Environmental Health Sciences , Research Triangle Park , North Carolina 27709 , United States
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Shears SB, Wang H. Inositol phosphate kinases: Expanding the biological significance of the universal core of the protein kinase fold. Adv Biol Regul 2019; 71:118-127. [PMID: 30392847 PMCID: PMC9364425 DOI: 10.1016/j.jbior.2018.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 10/23/2018] [Accepted: 10/26/2018] [Indexed: 05/06/2023]
Abstract
The protein kinase family is characterized by substantial conservation of architectural elements that are required for both ATP binding and phosphotransferase activity. Many of these structural features have also been identified in homologous enzymes that phosphorylate a variety of alternative, non-protein substrates. A comparative structural analysis of these different kinase sub-classes is a portal to a greater understanding of reaction mechanisms, enzyme regulation, inhibitor-development strategies, and superfamily-level evolutionary relationships. To serve such advances, we review structural elements of the protein kinase fold that are conserved in the subfamily of inositol phosphate kinases (InsPKs) that share a PxxxDxKxG catalytic signature: inositol 1,4,5-trisphosphate kinase (IP3K), inositol hexakisphosphate kinase (IP6K), and inositol polyphosphate multikinase (IPMK). We describe conservation of the fundamental two-lobe kinase architecture: an N-lobe constructed upon an anti-parallel β-strand scaffold, which is coupled to a largely helical C-lobe by a single, adenine-binding hinge. This equivalency also includes a G-loop that embraces the β/γ-phosphates of ATP, a transition-state stabilizing residue (Lys/His), and a Mg-positioning aspartate residue within a catalytic triad. Furthermore, we expand this list of conserved structural features to include some not previously identified in InsPKs: a 'gatekeeper' residue in the N-lobe, and an 'αF'-like helix in the C-lobe that anchors two structurally-stabilizing, hydrophobic spines, formed from non-consecutive residues that span the two lobes. We describe how this wide-ranging structural homology can be exploited to develop lead inhibitors of IP6K and IPMK, by using strategies similar to those that have generated ATP-competing inhibitors of protein-kinases. We provide several examples to illustrate how such an approach could benefit human health.
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Affiliation(s)
- Stephen B Shears
- Inositol Signaling Group, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.
| | - Huanchen Wang
- Inositol Signaling Group, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.
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25
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Carlson JC, Nidey NL, Butali A, Buxo CJ, Christensen K, Deleyiannis FWD, Hecht JT, Field LL, Moreno-Uribe LM, Orioli IM, Poletta FA, Padilla C, Vieira AR, Weinberg SM, Wehby GL, Feingold E, Murray JC, Marazita ML, Leslie EJ. Genome-wide interaction studies identify sex-specific risk alleles for nonsyndromic orofacial clefts. Genet Epidemiol 2018; 42:664-672. [PMID: 30277614 PMCID: PMC6185762 DOI: 10.1002/gepi.22158] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/17/2018] [Accepted: 07/28/2018] [Indexed: 01/11/2023]
Abstract
Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is the most common craniofacial birth defect in humans and is notable for its apparent sexual dimorphism where approximately twice as many males are affected as females. The sources of this disparity are largely unknown, but interactions between genetic and sex effects are likely contributors. We examined gene-by-sex (G × S) interactions in a worldwide sample of 2,142 NSCL/P cases and 1,700 controls recruited from 13 countries. First, we performed genome-wide joint tests of the genetic (G) and G × S effects genome-wide using logistic regression assuming an additive genetic model and adjusting for 18 principal components of ancestry. We further interrogated loci with suggestive results from the joint test ( p < 1.00 × 10 -5 ) by examining the G × S effects from the same model. Out of the 133 loci with suggestive results ( p < 1.00 × 10 -5 ) for the joint test, we observed one genome-wide significant G × S effect in the 10q21 locus (rs72804706; p = 6.69 × 10 -9 ; OR = 2.62 CI [1.89, 3.62]) and 16 suggestive G × S effects. At the intergenic 10q21 locus, the risk of NSCL/P is estimated to increase with additional copies of the minor allele for females, but the opposite effect for males. Our observation that the impact of genetic variants on NSCL/P risk differs for males and females may further our understanding of the genetic architecture of NSCL/P and the sex differences underlying clefts and other birth defects.
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Affiliation(s)
- Jenna C. Carlson
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
- Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Nichole L. Nidey
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, IA 52246
| | - Azeez Butali
- Department of Oral Pathology, Radiology and Medicine, Dows Institute for Dental Research, College of Dentistry, University of Iowa, Iowa City, IA, 52242, USA
| | - Carmen J. Buxo
- Dental and Craniofacial Genomics Core, School of Dental Medicine, University of Puerto Rico, San Juan, 00936, Puerto Rico
| | - Kaare Christensen
- Department of Epidemiology, Institute of Public Health, University of Southern Denmark, Odense, DK-5230, Denmark
| | - Frederic W-D Deleyiannis
- Department of Surgery, Plastic and Reconstructive Surgery, University of Colorado School of Medicine, Denver, CO, 80045, USA
| | - Jacqueline T. Hecht
- Department of Pediatrics, McGovern Medical School and School of Dentistry UT Health at Houston, Houston, TX, 77030, USA
| | - L. Leigh Field
- Department of Medical Genetics, University of British Columbia, Vancouver, V6H 3N1, Canada
| | - Lina M. Moreno-Uribe
- Department of Orthodontics, College of Dentistry, University of Iowa, Iowa City, IA, 52242, USA
| | - Ieda M. Orioli
- ECLAMC (Latin American Collaborative Study of Congenital Malformations) at INAGEMP (National Institute of Population Medical Genetics), Rio de Janeiro, Brazil
- Department of Genetics, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, 21941-617, Brazil
| | - Fernando A. Poletta
- ECLAMC (Latin American Collaborative Study of Congenital Malformations) at INAGEMP (National Institute of Population Medical Genetics), Rio de Janeiro, Brazil
- CEMIC-CONICET: Center for Medical Education and Clinical Research “Norberto Quirno”, Buenos Aires, 1431, Argentina
| | - Carmencita Padilla
- Department of Pediatrics, College of Medicine, University of the Philippines Manila, 1000 and the Philippine Genome Center, University of the Philippines System 1101, The Philippines
| | - Alexandre R. Vieira
- Center for Craniofacial and Dental Genetics, Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - Seth M. Weinberg
- Center for Craniofacial and Dental Genetics, Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - George L. Wehby
- Department of Health Management and Policy, College of Public Health, University of Iowa, Iowa City, IA, 52242, USA
| | - Eleanor Feingold
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
- Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Jeffrey C. Murray
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa,52242, USA
| | - Mary L. Marazita
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
- Center for Craniofacial and Dental Genetics, Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - Elizabeth J. Leslie
- Department of Human Genetics, Emory University School of Medicine, Emory University, Atlanta, GA, 30322, USA
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Fu P, Ebenezer DL, Ha AW, Suryadevara V, Harijith A, Natarajan V. Nuclear lipid mediators: Role of nuclear sphingolipids and sphingosine-1-phosphate signaling in epigenetic regulation of inflammation and gene expression. J Cell Biochem 2018; 119:6337-6353. [PMID: 29377310 DOI: 10.1002/jcb.26707] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/23/2018] [Indexed: 12/18/2022]
Abstract
Phospholipids, sphingolipids, and cholesterol are integral components of eukaryotic cell organelles, including the nucleus. Recent evidence shows characteristic features of nuclear lipid composition and signaling, which are distinct from that of the cytoplasm and plasma membrane. While the nuclear phosphoinositol lipid signaling in cell cycle regulation and differentiation has been well described, there is a paucity on the role of nuclear sphingolipids and sphingolipid signaling in different physiological and pathophysiological human conditions. In this prospective, we describe the role of sphingolipids and specifically focus on the sphingoid bases, such as sphingosine, ceramide, and sphingosine-1-phosphate (S1P) generation and catabolism in nuclear signaling and function. Particularly, S1P generated in the nucleus by phosphorylation of SPHK2 modulates HDAC activity either by direct binding or through activation of nuclear reactive oxygen species and regulates cell cycle and pro-inflammatory gene expression. Potential implication of association of SPHK2 with the co-repressor complexes and generation of S1P in the nucleus on chromatin remodeling under normal and pathological conditions is discussed. A better understanding of sphingolipid signaling in the nucleus will facilitate the design and development of new and novel therapeutic approaches to modulate expression of pro-inflammatory and cell cycle dependent genes in human pathologies such as cancer, bacterial lung infection, neurodegeneration, and cystic fibrosis.
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Affiliation(s)
- Panfeng Fu
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois
| | - David L Ebenezer
- Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois
| | - Alison W Ha
- Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois
| | | | - Anantha Harijith
- Department of Pediatrics, University of Illinois, Chicago, Illinois
| | - Viswanathan Natarajan
- Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois.,Department of Medicine, University of Illinois, Chicago, Illinois
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Pancreatic and renal function in streptozotocin-induced type 2 diabetic rats administered combined inositol hexakisphosphate and inositol supplement. Biomed Pharmacother 2017; 96:72-77. [PMID: 28965010 DOI: 10.1016/j.biopha.2017.09.126] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 09/23/2017] [Accepted: 09/24/2017] [Indexed: 11/23/2022] Open
Abstract
Diabetes mellitus, as a result of microvascular and macrovascular injury, causes organ dysfunction in a wide variety of tissues. The objective of this study was to investigate the effect of combined inositol hexakisphosphate and inositol supplement on renal and pancreatic integrity in type 2 diabetic rats. Thirty male Sprague-Dawley rats were divided into five groups (n=6 per group). Type 2 diabetes was induced in three groups using high-fat diet combined with a single dose of streptozotocin (35mg/kg body weight, intraperitoneally). Two of the diabetic groups were treated with combined IP6 and inositol or glibenclamide. Serum biochemical markers of kidney damage kidney, antioxidant status (superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) and lipid peroxidation were measured. Histomorphological and morphometric examinations of the H&E stained pancreas were also carried out. The administration of combined IP6 and inositol supplement resulted in 64% and 27% increase in CAT activities and GSH levels respectively and a 25% decrease in lipid peroxidation level compared to the diabetic control. Serum uric acid, creatinine and BUN levels in the combination treated group was comparable to the normal control. Examination of H&E stained pancreatic sections showed a significant increase (107%) in the number of islets in the combined IP6 and inositol treated group compared to the untreated diabetic group. Overall, the treatment of type 2 diabetic rats with combined IP6 and inositol supplement resulted in the improvement of renal and pancreatic function.
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