1
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Ha HJ, Park HH. Molecular basis of apoptotic DNA fragmentation by DFF40. Cell Death Dis 2022; 13:198. [PMID: 35236824 PMCID: PMC8891305 DOI: 10.1038/s41419-022-04662-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 02/03/2022] [Accepted: 02/16/2022] [Indexed: 11/09/2022]
Abstract
AbstractAlthough the functions of CIDE domain-containing proteins, including DFF40, DFF45, CIDE-A, CIDE-B, and FSP27, in apoptotic DNA fragmentation and lipid homeostasis have been studied extensively in mammals, the functions of four CIDE domain-containing proteins identified in the fly, namely DREP1, 2, 3, and 4, have not been explored much. Recent structural study of DREP4, a fly orthologue of mammalian DFF40 (an endonuclease involved in apoptotic DNA fragmentation), showed that the CIDE domain of DREP4 (and DFF40) forms filament-like assembly, which is critical for the corresponding function. The current study aimed to investigate the mechanism of filament formation of DREP4 CIDE and to characterize the same. DREP4 CIDE was shown to specifically bind to histones H1 and H2, an event important for the nuclease activity of DREP4. Based on the current experimental results, we proposed the mechanism underlying the process of apoptotic DNA fragmentation.
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2
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Lee SY, Kwon S, Ha HJ, Lee SH, Park HH. Helical filament structure of the DREP3 CIDE domain reveals a unified mechanism of CIDE-domain assembly. Acta Crystallogr D Struct Biol 2021; 77:1543-1553. [PMID: 34866610 PMCID: PMC8647176 DOI: 10.1107/s2059798321010767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 10/18/2021] [Indexed: 12/04/2022] Open
Abstract
The cell-death-inducing DFF45-like effector (CIDE) domain is a protein-interaction module comprising ∼80 amino acids and was initially identified in several apoptotic nucleases and their regulators. CIDE-domain-containing proteins were subsequently identified among proteins involved in lipid metabolism. Given the involvement of CIDE-domain-containing proteins in cell death and lipid homeostasis, their structure and function have been intensively studied. Here, the head-to-tail helical filament structure of the CIDE domain of DNA fragmentation factor-related protein 3 (DREP3) is presented. The helical filament structure was formed by opposing positively and negatively charged interfaces of the domain and was assembled depending on protein and salt concentrations. Although conserved filament structures are observed in CIDE family members, the structure elucidated in this study and its comparison with previous structures indicated that the size and the number of molecules used in one turn vary. These findings suggest that this charged-surface-based head-to-tail helical filament structure represents a unified mechanism of CIDE-domain assembly and provides insight into the function of various forms of the filament structure of the CIDE domain in higher-order assembly for apoptotic DNA fragmentation and control of lipid-droplet size.
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Affiliation(s)
- So Yeon Lee
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
| | - Sunghark Kwon
- Department of Biotechnology, Konkuk University, Chungju, Chungbuk 27478, Republic of Korea
| | - Hyun Ji Ha
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
| | - Sung Hoon Lee
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Hyun Ho Park
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
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3
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Assembly of platforms for signal transduction in the new era: dimerization, helical filament assembly, and beyond. Exp Mol Med 2020; 52:356-366. [PMID: 32139779 PMCID: PMC7156525 DOI: 10.1038/s12276-020-0391-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Accepted: 01/31/2020] [Indexed: 11/08/2022] Open
Abstract
Supramolecular organizing center (SMOC)-mediated signal transduction is an emerging concept in the field of signal transduction that is ushering in a new era. The formation of location-specific, higher-order SMOCs is particularly important for cell death and innate immune signaling processes. Several protein interaction domains, including the death domain (DD) superfamily and the CIDE domain, are representative mediators of SMOC assembly in cell death and innate immune signaling pathways. DD superfamily- and CIDE domain-containing proteins form SMOCs that activate various caspases and provide signaling scaffold platforms. These assemblies can lead to signal transduction and amplification during signaling events. In this review, we summarize recent findings on the molecular basis of DD superfamily- and CIDE domain-mediated SMOC formation. Improved understanding of large molecular signaling complexes that form during innate (nonspecific) immune responses could help develop treatments for multiple diseases including cancer. Correct cell signaling requires precise protein interactions and binding, which are mediated by specific sites on the surface of the protein molecules involved. Innate immune responses and cell death mechanisms rely on such protein interactions, and defects can cause signaling abnormalities and trigger disease. Hyun Ho Park and co-workers at Chung-Ang University in Seoul, South Korea, reviewed recent insights into the presence of supramolecular organizing centers (SMOCs), localized complexes of signaling proteins that form during immune responses. The researchers highlight existing understanding of SMOC assembly processes. A better understanding of SMOCs will help to explain enzyme activation, signal amplification and cell signaling control mechanisms.
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4
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Crystal structure and mutation analysis revealed that DREP2 CIDE forms a filament-like structure with features differing from those of DREP4 CIDE. Sci Rep 2018; 8:17810. [PMID: 30546036 PMCID: PMC6292858 DOI: 10.1038/s41598-018-36253-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/16/2018] [Indexed: 11/26/2022] Open
Abstract
Cell death-inducing DFF45-like effect (CIDE) domain-containing proteins, DFF40, DFF45, CIDE-A, CIDE-B, and FSP27, play important roles in apoptotic DNA fragmentation and lipid homeostasis. The function of DFF40/45 in apoptotic DNA fragmentation is mediated by CIDE domain filament formation. Although our recent structural study of DREP4 CIDE revealed the first filament-like structure of the CIDE domain and its functional importance, the filament structure of DREP2 CIDE is unclear because this structure was not helical in the asymmetric unit. In this study, we present the crystal structure and mutagenesis analysis of the DREP2 CIDE mutant, which confirmed that DREP2 CIDE also forms a filament-like structure with features differing from those of DREP4 CIDE.
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5
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Wang J, Yan C, Xu C, Chua BT, Li P, Chen FJ. Polybasic RKKR motif in the linker region of lipid droplet (LD)-associated protein CIDEC inhibits LD fusion activity by interacting with acidic phospholipids. J Biol Chem 2018; 293:19330-19343. [PMID: 30361435 DOI: 10.1074/jbc.ra118.004892] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 10/24/2018] [Indexed: 12/17/2022] Open
Abstract
Lipid droplets (LDs) are intracellular organelles and a central site for lipid synthesis, storage, and mobilization. The size of LDs reflects the dynamic regulation of lipid metabolism in cells. Previously, we found that cell death-inducing DFFA-like effector C (CIDEC) mediates LD fusion and growth by lipid transfer through LD-LD contact sites in adipocytes and hepatocytes. The CIDE-N domains of CIDEC molecules form homodimers, whereas the CIDE-C domain plays an important role in LD targeting and enrichment. Here, using targeted protein deletions and GFP expression coupled with fluorescence microscopy, we identified a polybasic RKKR motif in the linker region that connects the CIDE-N and CIDE-C domains of CIDEC and functions as a regulatory motif for LD fusion. We found that deletion of the linker region or mutation of the RKKR motif increases the formation of supersized LDs compared with LD formation in cells with WT CIDEC. This enhanced LD fusion activity required the interaction between CIDE-N domains. Mechanistically, we found that the RKKR motif interacts with acidic phospholipids via electrostatic attraction. Loss of this motif disrupted the protein-lipid interaction, resulting in enhanced lipid droplet fusion activity and thus formation of larger LDs. In summary, we have uncovered a CIDEC domain that regulates LD fusion activity, a finding that provides insights into the inhibitory regulation of LD fusion through CIDEC-lipid interactions.
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Affiliation(s)
- Jia Wang
- From the State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084
| | - Chengsong Yan
- the State Key Laboratory of Molecular Biology, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, and
| | - Chenqi Xu
- the State Key Laboratory of Molecular Biology, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, and
| | - Boon Tin Chua
- the Institute of Metabolism and Integrative Biology, Fudan University, Shanghai 200438, China
| | - Peng Li
- From the State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084,
| | - Feng-Jung Chen
- From the State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, .,the Institute of Metabolism and Integrative Biology, Fudan University, Shanghai 200438, China
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6
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Fan JB, Liu W, Zhu XH, Yi H, Cui SY, Zhao JN, Cui ZM. microRNA-25 targets PKCζ and protects osteoblastic cells from dexamethasone via activating AMPK signaling. Oncotarget 2018; 8:3226-3236. [PMID: 27911275 PMCID: PMC5356877 DOI: 10.18632/oncotarget.13698] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/14/2016] [Indexed: 12/21/2022] Open
Abstract
AMP-activated protein kinase (AMPK) activation could protect osteoblasts from dexamethasone (Dex). This study aims to provoke AMPK activation via microRNA downregulation of its negative regulator protein kinase C ζ (PKCζ). Results show that microRNA-25-5p (miR-25-5p) targets PKCζ's 3’ untranslated regions (UTRs). Forced-expression of miR-25 downregulated PKCζ and activated AMPK in human osteoblastic cells (OB-6 and hFOB1.19 lines), which thereafter protected cells from Dex. Reversely, expression of antagomiR-25, the miR-25 inhibitor, upregulated PKCζ and inhibited AMPK activation, exacerbating Dex damages. Notably, PKCζ shRNA knockdown similarly activated AMPK and protected osteoblastic cells from Dex. AMPK activation was required for miR-25-induced osteoblastic cell protection. AMPKα shRNA or dominant negative mutation almost completely blocked miR-25-induced cytoprotection against Dex. Further studies showed that miR-25 expression increased NADPH activity and suppressed Dex-induced oxidative stress in osteoblastic cells. Such effects by miR-25 were abolished with AMPKα knockdown or mutation. Significantly, miR-25-5p level was increased in patients’ necrotic femoral head tissues, which was correlated with PKCζ downregulation and AMPK hyper-activation. These results suggest that miR-25-5p targets PKCζ and protects osteoblastic cells from Dex possibly via activating AMPK signaling.
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Affiliation(s)
- Jian-Bo Fan
- Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China.,Department of Orthopaedics, Jinling Hospital, Nanjing Medical University, Nanjing 210008, Jiangsu, PR China
| | - Wei Liu
- Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China
| | - Xin-Hui Zhu
- Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China
| | - Hong Yi
- Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China
| | - Sheng-Yu Cui
- Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China
| | - Jian-Ning Zhao
- Department of Orthopaedics, Jinling Hospital, Nanjing Medical University, Nanjing 210008, Jiangsu, PR China
| | - Zhi-Ming Cui
- Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China
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7
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Kim CM, Jeon SH, Choi JH, Lee JH, Park HH. Interaction mode of CIDE family proteins in fly: DREP1 and DREP3 acidic surfaces interact with DREP2 and DREP4 basic surfaces. PLoS One 2017; 12:e0189819. [PMID: 29240809 PMCID: PMC5730196 DOI: 10.1371/journal.pone.0189819] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 12/01/2017] [Indexed: 11/19/2022] Open
Abstract
Cell death-inducing DNA fragmentation factor 45 (DFF45)-like effector (CIDE) domains were initially identified as protein interaction modules in apoptotic nucleases and are now known to form a highly conserved family with diverse functions that range from cell death to lipid homeostasis. In the fly, four CIDE domain-containing proteins (DFF-related protein [DREP]-1–4) and their functions, including interaction relationships, have been identified. In this study, we introduced and investigated acidic side-disrupted mutants of DREP1, DREP2, and DREP3. We discovered that the acidic surface patches of DREP1 and DREP3 are critical for the homo-dimerization. In addition, we found that the acidic surface sides of DREP1 and DREP3 interact with the basic surface sides of DREP2 and DREP4. Our current study provides clear evidence demonstrating the mechanism of the interactions between four DREP proteins in the fly.
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Affiliation(s)
- Chang Min Kim
- School of Natural Science, Department of Chemistry and Biochemistry and Graduate School of Biochemistry, Yeungnam University, Gyeongsan, Republic of Korea
| | - Sun Hee Jeon
- School of Natural Science, Department of Chemistry and Biochemistry and Graduate School of Biochemistry, Yeungnam University, Gyeongsan, Republic of Korea
| | - Jun-Hyuk Choi
- Department of Metrology for Quality of Life, Center for Bioanalysis, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea
| | - Jun Hyuck Lee
- Unit of Polar Genomics, Korea Polar Research Institute, Inchon, Republic of Korea
| | - Hyun Ho Park
- School of Natural Science, Department of Chemistry and Biochemistry and Graduate School of Biochemistry, Yeungnam University, Gyeongsan, Republic of Korea
- * E-mail:
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8
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Gao G, Chen FJ, Zhou L, Su L, Xu D, Xu L, Li P. Control of lipid droplet fusion and growth by CIDE family proteins. Biochim Biophys Acta Mol Cell Biol Lipids 2017. [DOI: 10.1016/j.bbalip.2017.06.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Engin A. Fat Cell and Fatty Acid Turnover in Obesity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 960:135-160. [PMID: 28585198 DOI: 10.1007/978-3-319-48382-5_6] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. Inhibition of adipose triglyceride lipase leads to an accumulation of triglyceride, whereas inhibition of hormone-sensitive lipase leads to the accumulation of diacylglycerol. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride turnover. Excess triacylglycerols (TAGs), sterols and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets. Following the release of lipid droplets from endoplasmic reticulum, cytoplasmic lipid droplets increase their volume either by local TAG synthesis or by homotypic fusion. The number and the size of lipid droplet distribution is correlated with obesity. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. NOD-like receptors family pyrin domain containing 3 (NLRP3) inflammasome-dependent caspase-1 activation in hypertrophic adipocytes induces obese adipocyte death by pyroptosis. Actually adipocyte death may be a prerequisite for the transition from hypertrophic to hyperplastic obesity. Major transcriptional factors, CCAAT/enhancer-binding proteins beta and delta, play a central role in the subsequent induction of critical regulators, peroxisome-proliferator-activated receptor gamma, CCAAT/enhancer-binding protein alpha and sterol regulatory element-binding protein 1, in the transcriptional control of adipogenesis in obesity.Collectively, in this chapter the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of lipid droplet interactions with the other cellular organelles are reviewed. Furthermore, in addition to lipid droplet growth, the functional link between the adipocyte-specific lipid droplet-associated protein and fatty acid turn-over is also debated.
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Affiliation(s)
- Atilla Engin
- Faculty of Medicine, Department of General Surgery, Gazi University, Besevler, Ankara, Turkey. .,, Mustafa Kemal Mah. 2137. Sok. 8/14, 06520, Cankaya, Ankara, Turkey.
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10
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CIDE domains form functionally important higher-order assemblies for DNA fragmentation. Proc Natl Acad Sci U S A 2017; 114:7361-7366. [PMID: 28652364 DOI: 10.1073/pnas.1705949114] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cell death-inducing DFF45-like effector (CIDE) domains, initially identified in apoptotic nucleases, form a family with diverse functions ranging from cell death to lipid homeostasis. Here we show that the CIDE domains of Drosophila and human apoptotic nucleases Drep2, Drep4, and DFF40 all form head-to-tail helical filaments. Opposing positively and negatively charged interfaces mediate the helical structures, and mutations on these surfaces abolish nuclease activation for apoptotic DNA fragmentation. Conserved filamentous structures are observed in CIDE family members involved in lipid homeostasis, and mutations on the charged interfaces compromise lipid droplet fusion, suggesting that CIDE domains represent a scaffold for higher-order assembly in DNA fragmentation and other biological processes such as lipid homeostasis.
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11
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Nishimoto Y, Nakajima S, Tateya S, Saito M, Ogawa W, Tamori Y. Cell death-inducing DNA fragmentation factor A-like effector A and fat-specific protein 27β coordinately control lipid droplet size in brown adipocytes. J Biol Chem 2017; 292:10824-10834. [PMID: 28490632 DOI: 10.1074/jbc.m116.768820] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 05/09/2017] [Indexed: 12/13/2022] Open
Abstract
Adipose tissue stores neutral lipids and is a major metabolic organ involved in regulating whole-body energy homeostasis. Triacylglycerol is stored as unilocular large lipid droplets (LDs) in white adipocytes and as multilocular small LDs in brown adipocytes. Proteins of the cell death-inducing DNA fragmentation factor A-like effector (Cide) family include CideA, CideB, and fat-specific protein of 27 (FSP27). Of these, FSP27 has been shown to play a crucial role in the formation of unilocular large LDs in white adipocytes. However, the mechanisms by which brown adipocytes store small and multilocular LDs remain unclear. An FSP27 isoform, FSP27β, was recently identified. We herein report that CideA and FSP27β are mainly expressed in brown adipose tissue and that FSP27β overexpression inhibits CideA-induced LD enlargements in a dose-dependent manner in COS cells. Furthermore, RNAi-mediated FSP27β depletion resulted in enlarged LDs in HB2 adipocytes, which possess the characteristics of brown adipocytes. Brown adipocytes in FSP27-knock-out mice that express CideA, but not FSP27β, had larger and fewer LDs. Moreover, we confirmed that FSP27β and CideA form a complex in brown adipose tissue. Our results suggest that FSP27β negatively regulates CideA-promoted enlargement of LD size in brown adipocytes. FSP27β appears to be responsible for the formation of small and multilocular LDs in brown adipose tissue, a morphology facilitating free fatty acid transport to mitochondria adjacent to LDs for oxidation in brown adipocytes.
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Affiliation(s)
- Yuki Nishimoto
- From the Department of Internal Medicine, Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Shinsuke Nakajima
- From the Department of Internal Medicine, Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Sanshiro Tateya
- From the Department of Internal Medicine, Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.,Department of Internal Medicine, Division of Diabetes, Kakogawa Central City Hospital, Kakogawa 675-8611, Japan
| | - Masayuki Saito
- Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan, and
| | - Wataru Ogawa
- From the Department of Internal Medicine, Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Yoshikazu Tamori
- From the Department of Internal Medicine, Division of Diabetes and Endocrinology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan, .,Department of Internal Medicine, Division of Diabetes and Endocrinology, Chibune General Hospital, Osaka 555-0001, Japan
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12
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Tamori Y, Tateya S, Ijuin T, Nishimoto Y, Nakajima S, Ogawa W. Negatively-charged residues in the polar carboxy-terminal region in FSP27 are indispensable for expanding lipid droplets. FEBS Lett 2016; 590:750-9. [PMID: 26921608 DOI: 10.1002/1873-3468.12114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 02/03/2016] [Accepted: 02/23/2016] [Indexed: 12/13/2022]
Abstract
FSP27 has an important role in large lipid droplet (LD) formation because it exchanges lipids at the contact site between LDs. In the present study, we clarify that the amino-terminal domain of FSP27 (amino acids 1-130) is dispensable for LD enlargement, although it accelerates LD growth. LD expansion depends on the carboxy-terminal domain of FSP27 (amino acids 131-239). Especially, the negative charge of the acidic residues (D215, E218, E219 and E220) in the polar carboxy-terminal region (amino acids 202-239) is essential for the enlargement of LD. We propose that the carboxy-terminal domain of FSP27 has a crucial role in LD expansion, whereas the amino-terminal domain only has a supportive role.
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Affiliation(s)
- Yoshikazu Tamori
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Chibune General Hospital, Osaka, Japan.,Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Sanshiro Tateya
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan.,Division of Diabetes, Department of Internal Medicine, Kakogawa West City Hospital, Japan
| | - Takeshi Ijuin
- Division of Biochemistry, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Japan
| | - Yuki Nishimoto
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Shinsuke Nakajima
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Wataru Ogawa
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
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13
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Barneda D, Planas-Iglesias J, Gaspar ML, Mohammadyani D, Prasannan S, Dormann D, Han GS, Jesch SA, Carman GM, Kagan V, Parker MG, Ktistakis NT, Klein-Seetharaman J, Dixon AM, Henry SA, Christian M. The brown adipocyte protein CIDEA promotes lipid droplet fusion via a phosphatidic acid-binding amphipathic helix. eLife 2015; 4:e07485. [PMID: 26609809 PMCID: PMC4755750 DOI: 10.7554/elife.07485] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 11/25/2015] [Indexed: 12/22/2022] Open
Abstract
Maintenance of energy homeostasis depends on the highly regulated storage and release of triacylglycerol primarily in adipose tissue, and excessive storage is a feature of common metabolic disorders. CIDEA is a lipid droplet (LD)-protein enriched in brown adipocytes promoting the enlargement of LDs, which are dynamic, ubiquitous organelles specialized for storing neutral lipids. We demonstrate an essential role in this process for an amphipathic helix in CIDEA, which facilitates embedding in the LD phospholipid monolayer and binds phosphatidic acid (PA). LD pairs are docked by CIDEA trans-complexes through contributions of the N-terminal domain and a C-terminal dimerization region. These complexes, enriched at the LD–LD contact site, interact with the cone-shaped phospholipid PA and likely increase phospholipid barrier permeability, promoting LD fusion by transference of lipids. This physiological process is essential in adipocyte differentiation as well as serving to facilitate the tight coupling of lipolysis and lipogenesis in activated brown fat. DOI:http://dx.doi.org/10.7554/eLife.07485.001 If other energy sources become unavailable, cells fall back on stores of fatty molecules called lipids. These are held in membrane-enclosed compartments in the cell called lipid droplets, which in mammals are particularly abundant in fat cells called adipocytes. There are two main types of adipocytes: white adipocytes have a single giant lipid droplet, whereas brown adipocytes contain many smaller droplets. Proteins embedded in the membrane that surrounds a lipid droplet help to control the droplet’s growth and when it releases lipids. For example, a protein called CIDEA, which is only found in brown adipocytes, helps lipid droplets to grow by enabling one droplet to transfer its contents to another droplet. However, little is known about how this occurs. By combining cell biology, biophysical and computer modelling approaches, Barneda et al. investigated how normal and mutant forms of CIDEA affect the growth of lipid droplets. These experiments identified a helix in the structure of CIDEA that embeds it in the membrane, from where it can then interact with CIDEA proteins on other lipid droplets to hold the droplets together. In addition, the helix interacts with a molecule in the lipid droplet membrane called phosphatidic acid. Barneda et al. suggest that this interaction helps to transfer the contents of one droplet to another by making it easier for lipids to move through the droplets’ membranes. The next challenge is to characterize the mechanisms that control CIDEA activity to influence the formation of the multiple lipid droplets that distinguish brown and BRITE (brown-in-white) adipocytes from white adipocytes. The lipid droplets in brown adipocytes are an important target for research to combat obesity, due to the 'burning' rather than storing of lipids that occurs in these cells. DOI:http://dx.doi.org/10.7554/eLife.07485.002
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Affiliation(s)
- David Barneda
- Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom
| | | | - Maria L Gaspar
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Dariush Mohammadyani
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, United States
| | - Sunil Prasannan
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
| | - Dirk Dormann
- Microscopy Facility, MRC Clinical Sciences Centre, Imperial College London, London, United Kingdom
| | - Gil-Soo Han
- Department of Food Science, Rutgers Center for Lipid Research, Rutgers University, New Brunswick, United States
| | - Stephen A Jesch
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - George M Carman
- Department of Food Science, Rutgers Center for Lipid Research, Rutgers University, New Brunswick, United States
| | - Valerian Kagan
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, United States
| | - Malcolm G Parker
- Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom
| | | | - Judith Klein-Seetharaman
- Warwick Medical School, University of Warwick, Coventry, United Kingdom.,Department of Bioengineering, University of Pittsburgh, Pittsburgh, United States
| | - Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
| | - Susan A Henry
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Mark Christian
- Institute of Reproductive and Developmental Biology, Imperial College London, London, United Kingdom.,Warwick Medical School, University of Warwick, Coventry, United Kingdom
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14
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