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Fu L, Zhang J, Wang Y, Wu H, Xu X, Li C, Li J, Liu J, Wang H, Jiang X, Li Z, He Y, Liu P, Wu Y, Zou X, Liang B. LET-767 determines lipid droplet protein targeting and lipid homeostasis. J Cell Biol 2024; 223:e202311024. [PMID: 38551495 PMCID: PMC10982117 DOI: 10.1083/jcb.202311024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 02/22/2024] [Accepted: 03/12/2024] [Indexed: 04/02/2024] Open
Abstract
Lipid droplets (LDs) are composed of a core of neutral lipids wrapped by a phospholipid (PL) monolayer containing several hundred proteins that vary between different cells or organisms. How LD proteins target to LDs is still largely unknown. Here, we show that RNAi knockdown or gene mutation of let-767, encoding a member of hydroxysteroid dehydrogenase (HSD), displaced the LD localization of three well-known LD proteins: DHS-3 (dehydrogenase/reductase), PLIN-1 (perilipin), and DGAT-2 (diacylglycerol O-acyltransferase 2), and also prevented LD growth in Caenorhabditis elegans. LET-767 interacts with ARF-1 (ADP-ribosylation factor 1) to prevent ARF-1 LD translocation for appropriate LD protein targeting and lipid homeostasis. Deficiency of LET-767 leads to the release of ARF-1, which further recruits and promotes translocation of ATGL-1 (adipose triglyceride lipase) to LDs for lipolysis. The displacement of LD proteins caused by LET-767 deficiency could be reversed by inhibition of either ARF-1 or ATGL-1. Our work uncovers a unique LET-767 for determining LD protein targeting and maintaining lipid homeostasis.
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Affiliation(s)
- Lin Fu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Jingjing Zhang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Yanli Wang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Huiyin Wu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Xiumei Xu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Chunxia Li
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Jirong Li
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Jing Liu
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Haizhen Wang
- College of Veterinary Medicine, Yunnan Agricultural University, Kunming, China
| | - Xue Jiang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan province, Kunming Institute of Zoology, Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, China
| | - Zhihao Li
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Yaomei He
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yingjie Wu
- School of Laboratory Animal and Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
- Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Liaoning Provence Key Lab of Genome Engineered Animal Models Dalian Medical University, Dalian, China
| | - Xiaoju Zou
- College of Chinese Materia Medica and Yunnan Key Laboratory of Southern Medicinal Utilization, Yunnan University of Chinese Medicine, Kunming, China
| | - Bin Liang
- Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, School of Life Sciences, Yunnan University, Kunming, China
- Southwest United Graduate School, Kunming, China
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Shah DS, Nisr RB, Krasteva‐Christ G, Hundal HS. Caveolin-3 loss linked with the P104L LGMD-1C mutation modulates skeletal muscle mTORC1 signalling and cholesterol homeostasis. J Cachexia Sarcopenia Muscle 2023; 14:2310-2326. [PMID: 37671684 PMCID: PMC10570080 DOI: 10.1002/jcsm.13317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 07/20/2023] [Accepted: 07/31/2023] [Indexed: 09/07/2023] Open
Abstract
BACKGROUND Caveolins are the principal structural components of plasma membrane caveolae. Dominant pathogenic mutations in the muscle-specific caveolin-3 (Cav3) gene isoform, such as the limb girdle muscular dystrophy type 1C (LGMD-1C) P104L mutation, result in dramatic loss of the Cav3 protein and pathophysiological muscle weakness/wasting. We hypothesize that such muscle degeneration may be linked to disturbances in signalling events that impact protein turnover. Herein, we report studies assessing the effects of Cav3 deficiency on mammalian or mechanistic target of rapamycin complex 1 (mTORC1) signalling in skeletal muscle cells. METHODS L6 myoblasts were stably transfected with Cav3P104L or expression of native Cav3 was abolished by CRISPR/Cas9 genome editing (Cav3 knockout [Cav3KO]) prior to performing subcellular fractionation and immunoblotting, analysis of real-time mitochondrial respiration or fixed cell immunocytochemistry. Skeletal muscle from wild-type and Cav3-/- mice was processed for immunoblot analysis of downstream mTORC1 substrate phosphorylation. RESULTS Cav3 was detected in lysosomal-enriched membranes isolated from L6 myoblasts and observed by confocal microscopy to co-localize with lysosomal-specific markers. Cav3P104L expression, which results in significant (~95%) loss of native Cav3, or CRISPR/Cas9-mediated Cav3KO, reduced amino acid-dependent mTORC1 activation. The decline in mTORC1-directed signalling was detected by immunoblot analysis of L6 muscle cells and gastrocnemius Cav3-/- mouse muscle as judged by reduced phosphorylation of mTORC1 substrates that play key roles in the initiation of protein synthesis (4EBP1S65 and S6K1T389 ). S6K1T389 and 4EBP1S65 phosphorylation reduced by over 75% and 80% in Cav3KO muscle cells and by over 90% and 30% in Cav3-/- mouse skeletal muscle, respectively. The reduction in protein synthetic capacity in L6 muscle cells was confirmed by analysis of puromycylated peptides using the SUnSET assay. Cav3 loss was also associated with a 26% increase in lysosomal cholesterol, and pharmacological manipulation of lysosomal cholesterol was effective in replicating the reduction in mTORC1 activity observed in Cav3KO cells. Notably, re-expression of Cav3 in Cav3KO myoblasts normalized lysosomal cholesterol content, which coincided with a recovery in protein translation and an associated increase in mTORC1-directed phosphorylation of downstream targets. CONCLUSIONS Our findings indicate that Cav3 can localize on lysosomal membranes and is a novel regulator of mTORC1 signalling in muscle. Cav3 deficiency associated with the Cav3P104L mutation impairs mTORC1 activation and protein synthetic capacity in skeletal muscle cells, which may be linked to disturbances in lysosomal cholesterol trafficking and contribute to the pathology of LGMD-1C.
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Affiliation(s)
- Dinesh S. Shah
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life SciencesUniversity of DundeeDundeeDD1 5EHUK
| | - Raid B. Nisr
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life SciencesUniversity of DundeeDundeeDD1 5EHUK
| | | | - Harinder S. Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life SciencesUniversity of DundeeDundeeDD1 5EHUK
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Morales-Paytuví F, Fajardo A, Ruiz-Mirapeix C, Rae J, Tebar F, Bosch M, Enrich C, Collins BM, Parton RG, Pol A. Early proteostasis of caveolins synchronizes trafficking, degradation, and oligomerization to prevent toxic aggregation. J Cell Biol 2023; 222:e202204020. [PMID: 37526691 PMCID: PMC10394380 DOI: 10.1083/jcb.202204020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 04/05/2023] [Accepted: 06/09/2023] [Indexed: 08/02/2023] Open
Abstract
Caveolin-1 (CAV1) and CAV3 are membrane-sculpting proteins driving the formation of the plasma membrane (PM) caveolae. Within the PM mosaic environment, caveola assembly is unique as it requires progressive oligomerization of newly synthesized caveolins while trafficking through the biosynthetic-secretory pathway. Here, we have investigated these early events by combining structural, biochemical, and microscopy studies. We uncover striking trafficking differences between caveolins, with CAV1 rapidly exported to the Golgi and PM while CAV3 is initially retained in the endoplasmic reticulum and laterally moves into lipid droplets. The levels of caveolins in the endoplasmic reticulum are controlled by proteasomal degradation, and only monomeric/low oligomeric caveolins are exported into the cis-Golgi with higher-order oligomers assembling beyond this compartment. When any of those early proteostatic mechanisms are compromised, chemically or genetically, caveolins tend to accumulate along the secretory pathway forming non-functional aggregates, causing organelle damage and triggering cellular stress. Accordingly, we propose a model in which disrupted proteostasis of newly synthesized caveolins contributes to pathogenesis.
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Affiliation(s)
- Frederic Morales-Paytuví
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Alba Fajardo
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Carles Ruiz-Mirapeix
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - James Rae
- Institute for Molecular Bioscience (IMB), The University of Queensland (UQ) , Brisbane, Australia
| | - Francesc Tebar
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain
| | - Marta Bosch
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain
| | - Carlos Enrich
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain
| | - Brett M Collins
- Institute for Molecular Bioscience (IMB), The University of Queensland (UQ) , Brisbane, Australia
| | - Robert G Parton
- Institute for Molecular Bioscience (IMB), The University of Queensland (UQ) , Brisbane, Australia
- Centre for Microscopy and Microanalysis (CMM), The University of Queensland (UQ), Brisbane, Australia
| | - Albert Pol
- Lipid Trafficking and Disease Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA) , Barcelona, Spain
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Biochemical and Biophysical Characterization of the Caveolin-2 Interaction with Membranes and Analysis of the Protein Structural Alteration by the Presence of Cholesterol. Int J Mol Sci 2022; 23:ijms232315203. [PMID: 35216403 PMCID: PMC9736327 DOI: 10.3390/ijms232315203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/22/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
Caveolin-2 is a protein suitable for the study of interactions of caveolins with other proteins and lipids present in caveolar lipid rafts. Caveolin-2 has a lower tendency to associate with high molecular weight oligomers than caveolin-1, facilitating the study of its structural modulation upon association with other proteins or lipids. In this paper, we have successfully expressed and purified recombinant human caveolin-2 using E. coli. The structural changes of caveolin-2 upon interaction with a lipid bilayer of liposomes were characterized using bioinformatic prediction models, circular dichroism, differential scanning calorimetry, and fluorescence techniques. Our data support that caveolin-2 binds and alters cholesterol-rich domains in the membranes through a CARC domain, a type of cholesterol-interacting domain in its sequence. The far UV-CD spectra support that the purified protein keeps its folding properties but undergoes a change in its secondary structure in the presence of lipids that correlates with the acquisition of a more stable conformation, as shown by differential scanning calorimetry experiments. Fluorescence experiments using egg yolk lecithin large unilamellar vesicles loaded with 1,6-diphenylhexatriene confirmed that caveolin-2 adsorbs to the membrane but only penetrates the core of the phospholipid bilayer if vesicles are supplemented with 30% of cholesterol. Our study sheds light on the caveolin-2 interaction with lipids. In addition, we propose that purified recombinant caveolin-2 can provide a new tool to study protein-lipid interactions within caveolae.
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Abstract
Several studies have reported a significant association between the metabolic syndrome (MetS) and mortality around the world. Caveolin-1 (CAV-1) has been widely studied in dyslipidaemia, and several studies have indicated that CAV-1 genetic variations may correlate with dietary intake of fatty acids. This study aimed to investigate the interaction of CAV-1 rs3807992 with types of dietary fatty acid in the MetS risk. This cross-sectional study was carried out on 404 overweight and obese females. Dietary intake was obtained from a 147-item FFQ. The CAV-1 genotype was measured using the PCR-restriction fragment length polymorphism method. Anthropometric values and serum levels (TC, LDL, HDL, TAG and FBS) were measured by standard methods. It was observed that the (AA + AG) group had significantly higher BMI, waist circumference and DBP (P = 0·02, P = 0·02, and P = 0·01, respectively) and lower serum LDL, HDL and TC (P < 0·05) than the GG group. It was found that A allele carriers were at higher odds of the MetS (P = 0·01), abdominal obesity (P = 0·06), increased TAG concentration (P = 0·01), elevated blood pressure (BP) (P = 0·01), increased glucose concentration (P = 0·45) and decreased HDL-cholesterol concentration (P = 0·03). Moreover, the interaction of CAV-1 and SFA intake was significant in terms of the MetS (P = 0·03), LDL (P = 0·03) and BP (P = 0·01). Additionally, the (AA + AG) group was significantly related to PUFA intake in terms of the MetS (P = 0·04), TAG (P = 0·02), glucose (P = 0·02) and homoeostasis model assessment insulin resistance (P = 0·01). Higher PUFA consumption might attenuate the CAV-1 rs3807992 associations with the MetS, and individuals with greater genetic predisposition appeared to have a higher risk of the MetS, associated with higher SFA consumption.
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Hello from the other side: Membrane contact of lipid droplets with other organelles and subsequent functional implications. Prog Lipid Res 2021; 85:101141. [PMID: 34793861 DOI: 10.1016/j.plipres.2021.101141] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/10/2021] [Accepted: 11/10/2021] [Indexed: 02/06/2023]
Abstract
Lipid droplets (LDs) are ubiquitous organelles that play crucial roles in response to physiological and environmental cues. The identification of several neutral lipid synthesizing and regulatory protein complexes have propelled significant advance on the mechanisms of LD biogenesis in the endoplasmic reticulum (ER). Increasing evidence suggests that distinct proteins and regulatory factors, which localize to membrane contact sites (MCS), are involved not only in interorganellar lipid exchange and transport, but also function in other important cellular processes, including autophagy, mitochondrial dynamics and inheritance, ion signaling and inter-regulation of these MCS. More and more tethers and molecular determinants are associated to MCS and to a diversity of cellular and pathophysiological processes, demonstrating the dynamics and importance of these junctions in health and disease. The conjugation of lipids with proteins in supramolecular complexes is known to be paramount for many biological processes, namely membrane biosynthesis, cell homeostasis, regulation of organelle division and biogenesis, and cell growth. Ultimately, this physical organization allows the contact sites to function as crucial metabolic hubs that control the occurrence of chemical reactions. This leads to biochemical and metabolite compartmentalization for the purposes of energetic efficiency and cellular homeostasis. In this review, we will focus on the structural and functional aspects of LD-organelle interactions and how they ensure signaling exchange and metabolites transfer between organelles.
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Khatibi N, Mirzababaei A, Shiraseb F, Abaj F, Koohdani F, Mirzaei K. Interactions between caveolin 1 polymorphism and the Mediterranean and Mediterranean-DASH Intervention for Neurodegenerative Delay diet (MIND) diet on metabolic dyslipidemia in overweight and obese adult women: a cross-sectional study. BMC Res Notes 2021; 14:364. [PMID: 34544501 PMCID: PMC8454002 DOI: 10.1186/s13104-021-05777-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 09/07/2021] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE The increased prevalence of metabolic dyslipidemia (MD) and its association with a variety of disorders raised a lot of attention to its management. Caveolin 1 (CAV1) the key protein in the caval structure of plasma membranes is many cell types that play an important role in its function. (CAV1) is a known gene associated with obesity. Today, a novel diet recognized as the Mediterranean and Mediterranean-DASH Intervention for Neurodegenerative Delay diet (MIND) is reported to have a positive effect on overall health. Hence, we aimed to investigate the interactions between CAV1 polymorphism and MIND diet on the MD in overweight and obese patients. RESULTS Remarkably, there was a significant interaction between the MIND diet and CAV1 rs3807992 for dyslipidemia (β = - 0.25 ± 132, P = 0.05) in the crude model. Whereby, subjects with dominant alleles had a lower risk of dyslipidemia and risk allele carriers with higher adherence to the MIND diet may exhibit the lower dyslipidemia. This study presented the CAV1 gene as a possible genetic marker in recognizing people at higher risks for metabolic diseases. It also indicated that using the MIND diet may help in improving dyslipidemia through providing a probable interaction with CAV1 rs3807992 polymorphism.
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Affiliation(s)
- Nasim Khatibi
- Shahid Sadoughi University of Medical Science, Yazd, Iran
- Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences (TUMS), P.O. Box: 14155-6117, Tehran, Iran
| | - Atieh Mirzababaei
- Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences (TUMS), P.O. Box: 14155-6117, Tehran, Iran
| | - Farideh Shiraseb
- Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences (TUMS), P.O. Box: 14155-6117, Tehran, Iran
| | - Faezeh Abaj
- Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences (TUMS), P.O. Box: 14155-6117, Tehran, Iran
| | - Fariba Koohdani
- Department of Cellular, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences (TUMS), Molecular Nutrition, Tehran, Iran
| | - Khadijeh Mirzaei
- Department of Community Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences (TUMS), P.O. Box: 14155-6117, Tehran, Iran.
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Ma APY, Yeung CLS, Tey SK, Mao X, Wong SWK, Ng TH, Ko FCF, Kwong EML, Tang AHN, Ng IOL, Cai SH, Yun JP, Yam JWP. Suppression of ACADM-Mediated Fatty Acid Oxidation Promotes Hepatocellular Carcinoma via Aberrant CAV1/SREBP1 Signaling. Cancer Res 2021; 81:3679-3692. [PMID: 33975883 DOI: 10.1158/0008-5472.can-20-3944] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/24/2021] [Accepted: 04/27/2021] [Indexed: 12/24/2022]
Abstract
Lipid accumulation exacerbates tumor development, as it fuels the proliferative growth of cancer cells. The role of medium-chain acyl-CoA dehydrogenase (ACADM), an enzyme that catalyzes the first step of mitochondrial fatty acid oxidation, in tumor biology remains elusive. Therefore, investigating its mode of dysregulation can shed light on metabolic dependencies in cancer development. In hepatocellular carcinoma (HCC), ACADM was significantly underexpressed, correlating with several aggressive clinicopathologic features observed in patients. Functionally, suppression of ACADM promoted HCC cell motility with elevated triglyceride, phospholipid, and cellular lipid droplet levels, indicating the tumor suppressive ability of ACADM in HCC. Sterol regulatory element-binding protein-1 (SREBP1) was identified as a negative transcriptional regulator of ACADM. Subsequently, high levels of caveolin-1 (CAV1) were observed to inhibit fatty acid oxidation, which revealed its role in regulating lipid metabolism. CAV1 expression negatively correlated with ACADM and its upregulation enhanced nuclear accumulation of SREBP1, resulting in suppressed ACADM activity and contributing to increased HCC cell aggressiveness. Administration of an SREBP1 inhibitor in combination with sorafenib elicited a synergistic antitumor effect and significantly reduced HCC tumor growth in vivo. These findings indicate that deregulation of fatty acid oxidation mediated by the CAV1/SREBP1/ACADM axis results in HCC progression, which implicates targeting fatty acid metabolism to improve HCC treatment. SIGNIFICANCE: This study identifies tumor suppressive effects of ACADM in hepatocellular carcinoma and suggests promotion of β-oxidation to diminish fatty acid availability to cancer cells could be used as a therapeutic strategy.
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Affiliation(s)
- Angel P Y Ma
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Cherlie L S Yeung
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Sze Keong Tey
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Xiaowen Mao
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Samuel W K Wong
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Tung Him Ng
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Frankie C F Ko
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Ernest M L Kwong
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Alexander H N Tang
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Irene Oi-Lin Ng
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong, China
| | - Shao Hang Cai
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jing Ping Yun
- Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Judy W P Yam
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China. .,State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong, China
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Matthaeus C, Taraska JW. Energy and Dynamics of Caveolae Trafficking. Front Cell Dev Biol 2021; 8:614472. [PMID: 33692993 PMCID: PMC7939723 DOI: 10.3389/fcell.2020.614472] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/21/2020] [Indexed: 12/19/2022] Open
Abstract
Caveolae are 70–100 nm diameter plasma membrane invaginations found in abundance in adipocytes, endothelial cells, myocytes, and fibroblasts. Their bulb-shaped membrane domain is characterized and formed by specific lipid binding proteins including Caveolins, Cavins, Pacsin2, and EHD2. Likewise, an enrichment of cholesterol and other lipids makes caveolae a distinct membrane environment that supports proteins involved in cell-type specific signaling pathways. Their ability to detach from the plasma membrane and move through the cytosol has been shown to be important for lipid trafficking and metabolism. Here, we review recent concepts in caveolae trafficking and dynamics. Second, we discuss how ATP and GTP-regulated proteins including dynamin and EHD2 control caveolae behavior. Throughout, we summarize the potential physiological and cell biological roles of caveolae internalization and trafficking and highlight open questions in the field and future directions for study.
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Affiliation(s)
- Claudia Matthaeus
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
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Ramírez CM, Torrecilla-Parra M, Pardo-Marqués V, de-Frutos MF, Pérez-García A, Tabraue C, de la Rosa JV, Martín-Rodriguez P, Díaz-Sarmiento M, Nuñez U, Orizaola MC, Través PG, Camps M, Boscá L, Castrillo A. Crosstalk Between LXR and Caveolin-1 Signaling Supports Cholesterol Efflux and Anti-Inflammatory Pathways in Macrophages. Front Endocrinol (Lausanne) 2021; 12:635923. [PMID: 34122329 PMCID: PMC8190384 DOI: 10.3389/fendo.2021.635923] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/24/2021] [Indexed: 02/05/2023] Open
Abstract
Macrophages are immune cells that play crucial roles in host defense against pathogens by triggering their exceptional phagocytic and inflammatory functions. Macrophages that reside in healthy tissues also accomplish important tasks to preserve organ homeostasis, including lipid uptake/efflux or apoptotic-cell clearance. Both homeostatic and inflammatory functions of macrophages require the precise stability of lipid-rich microdomains located at the cell membrane for the initiation of downstream signaling cascades. Caveolin-1 (Cav-1) is the main protein responsible for the biogenesis of caveolae and plays an important role in vascular inflammation and atherosclerosis. The Liver X receptors (LXRs) are key transcription factors for cholesterol efflux and inflammatory gene responses in macrophages. Although the role of Cav-1 in cellular cholesterol homeostasis and vascular inflammation has been reported, the connection between LXR transcriptional activity and Cav-1 expression and function in macrophages has not been investigated. Here, using gain and loss of function approaches, we demonstrate that LXR-dependent transcriptional pathways modulate Cav-1 expression and compartmentation within the membrane during macrophage activation. As a result, Cav-1 participates in LXR-dependent cholesterol efflux and the control of inflammatory responses. Together, our data show modulation of the LXR-Cav-1 axis could be exploited to control exacerbated inflammation and cholesterol overload in the macrophage during the pathogenesis of lipid and immune disorders, such as atherosclerosis.
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Affiliation(s)
- Cristina M. Ramírez
- Instituto Madrileño de Estudios Avanzados (IMDEA) Research Institute of Food and Health Sciences, Madrid, Spain
- *Correspondence: Antonio Castrillo, ; Cristina M. Ramírez,
| | - Marta Torrecilla-Parra
- Instituto Madrileño de Estudios Avanzados (IMDEA) Research Institute of Food and Health Sciences, Madrid, Spain
| | - Virginia Pardo-Marqués
- Instituto Madrileño de Estudios Avanzados (IMDEA) Research Institute of Food and Health Sciences, Madrid, Spain
| | - Mario Fernández de-Frutos
- Instituto Madrileño de Estudios Avanzados (IMDEA) Research Institute of Food and Health Sciences, Madrid, Spain
| | - Ana Pérez-García
- Instituto Madrileño de Estudios Avanzados (IMDEA) Research Institute of Food and Health Sciences, Madrid, Spain
| | - Carlos Tabraue
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
- Departamento de Morfología, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Juan Vladimir de la Rosa
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Patricia Martín-Rodriguez
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Mercedes Díaz-Sarmiento
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Uxue Nuñez
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Marta C. Orizaola
- Instituto de Investigaciones Biomédicas “Alberto Sols”, Consejo Superior de Investigaciones Científicas CSIC-Universidad Autónoma de Madrid, Madrid, Spain
| | - Paqui G. Través
- Instituto de Investigaciones Biomédicas “Alberto Sols”, Consejo Superior de Investigaciones Científicas CSIC-Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta Camps
- Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Lisardo Boscá
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
- Instituto de Investigaciones Biomédicas “Alberto Sols”, Consejo Superior de Investigaciones Científicas CSIC-Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación en Red sobre Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Antonio Castrillo
- Unidad de Biomedicina (Unidad Asociada al CSIC), Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS) de la Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain
- Instituto de Investigaciones Biomédicas “Alberto Sols”, Consejo Superior de Investigaciones Científicas CSIC-Universidad Autónoma de Madrid, Madrid, Spain
- *Correspondence: Antonio Castrillo, ; Cristina M. Ramírez,
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11
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Buwa N, Mazumdar D, Balasubramanian N. Caveolin1 Tyrosine-14 Phosphorylation: Role in Cellular Responsiveness to Mechanical Cues. J Membr Biol 2020; 253:509-534. [PMID: 33089394 DOI: 10.1007/s00232-020-00143-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/05/2020] [Indexed: 02/07/2023]
Abstract
The plasma membrane is a dynamic lipid bilayer that engages with the extracellular microenvironment and intracellular cytoskeleton. Caveolae are distinct plasma membrane invaginations lined by integral membrane proteins Caveolin1, 2, and 3. Caveolae formation and stability is further supported by additional proteins including Cavin1, EHD2, Pacsin2 and ROR1. The lipid composition of caveolar membranes, rich in cholesterol and phosphatidylserine, actively contributes to caveolae formation and function. Post-translational modifications of Cav1, including its phosphorylation of the tyrosine-14 residue (pY14Cav1) are vital to its function in and out of caveolae. Cells that experience significant mechanical stress are seen to have abundant caveolae. They play a vital role in regulating cellular signaling and endocytosis, which could further affect the abundance and distribution of caveolae at the PM, contributing to sensing and/or buffering mechanical stress. Changes in membrane tension in cells responding to multiple mechanical stimuli affects the organization and function of caveolae. These mechanical cues regulate pY14Cav1 levels and function in caveolae and focal adhesions. This review, along with looking at the mechanosensitive nature of caveolae, focuses on the role of pY14Cav1 in regulating cellular mechanotransduction.
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Affiliation(s)
- Natasha Buwa
- Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Debasmita Mazumdar
- Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Nagaraj Balasubramanian
- Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.
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12
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Triacylglycerols sequester monotopic membrane proteins to lipid droplets. Nat Commun 2020; 11:3944. [PMID: 32769983 PMCID: PMC7414839 DOI: 10.1038/s41467-020-17585-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 07/08/2020] [Indexed: 01/05/2023] Open
Abstract
Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into organelles called lipid droplets (LDs). LDs are covered by a single phospholipid monolayer contiguous with the ER bilayer. This connection is used by several monotopic integral membrane proteins, with hydrophobic membrane association domains (HDs), to diffuse between the organelles. However, how proteins partition between ER and LDs is not understood. Here, we employed synthetic model systems and found that HD-containing proteins strongly prefer monolayers and returning to the bilayer is unfavorable. This preference for monolayers is due to a higher affinity of HDs for TG over membrane phospholipids. Protein distribution is regulated by PC/PE ratio via alterations in monolayer packing and HD-TG interaction. Thus, HD-containing proteins appear to non-specifically accumulate to the LD surface. In cells, protein editing mechanisms at the ER membrane would be necessary to prevent unspecific relocation of HD-containing proteins to LDs. Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into monolayer lipid droplets (LDs), but how proteins partition between ER and LDs is poorly understood. Here authors use synthetic model systems and find that proteins containing hydrophobic membrane association domains strongly prefer monolayers and that returning to the bilayer is unfavorable.
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13
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Chattopadhyay A, Singh R, Mitra M, Das AK, Maiti MK. Identification and functional characterization of a lipid droplet protein CtLDP1 from an oleaginous yeast Candida tropicalis SY005. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158725. [DOI: 10.1016/j.bbalip.2020.158725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 03/25/2020] [Accepted: 04/15/2020] [Indexed: 11/24/2022]
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14
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Affiliation(s)
- Robin W Klemm
- Department of Physiology, Anatomy and Genetics, University of Oxford, United Kingdom.
| | - Elina Ikonen
- Stem Cells and Metabolism Research Program and Dept. of Anatomy, Faculty of Medicine, University of Helsinki, Finland; Minerva Foundation Institute for Medical Research, Helsinki, Finland
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15
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Coleman RA. The "discovery" of lipid droplets: A brief history of organelles hidden in plain sight. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158762. [PMID: 32622088 DOI: 10.1016/j.bbalip.2020.158762] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 06/24/2020] [Accepted: 06/29/2020] [Indexed: 12/14/2022]
Abstract
Mammalian lipid droplets (LDs), first described as early as the 1880s, were virtually ignored for more than 100 years. Between 1991 and the early 2000s, however, a series of discoveries and conceptual breakthroughs led to a resurgent interest in obesity as a disease, in the metabolism of intracellular triacylglycerol (TAG), and in the physical locations of LDs as cellular structures with their associated proteins. Insights included the recognition that obesity underlies major chronic diseases, that appetite is hormonally controlled, that hepatic steatosis is not a benign finding, and that diabetes might fundamentally be a disorder of lipid metabolism. In this brief review, I describe the metamorphosis of LDs from overlooked globs of stored fat to dynamic organelles that control insulin resistance, mitochondrial oxidation, and viral replication.
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Affiliation(s)
- Rosalind A Coleman
- Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States of America.
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16
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Shah DS, Nisr RB, Stretton C, Krasteva-Christ G, Hundal HS. Caveolin-3 deficiency associated with the dystrophy P104L mutation impairs skeletal muscle mitochondrial form and function. J Cachexia Sarcopenia Muscle 2020; 11:838-858. [PMID: 32090499 PMCID: PMC7296273 DOI: 10.1002/jcsm.12541] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 11/22/2019] [Accepted: 01/07/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Caveolin-3 (Cav3) is the principal structural component of caveolae in skeletal muscle. Dominant pathogenic mutations in the Cav3 gene, such as the Limb Girdle Muscular Dystrophy-1C (LGMD1C) P104L mutation, result in substantial loss of Cav3 and myopathic changes characterized by muscle weakness and wasting. We hypothesize such myopathy may also be associated with disturbances in mitochondrial biology. Herein, we report studies assessing the effects of Cav3 deficiency on mitochondrial form and function in skeletal muscle cells. METHODS L6 myoblasts were stably transfected with Cav3P104L or expression of native Cav3 repressed by shRNA or CRISPR/Cas9 genome editing prior to performing fixed/live cell imaging of mitochondrial morphology, subcellular fractionation and immunoblotting, or analysis of real time mitochondrial respiration. Skeletal muscle from wild-type and Cav3-/- mice was processed for analysis of mitochondrial proteins by immunoblotting. RESULTS Caveolin-3 was detected in mitochondrial-enriched membranes isolated from mouse gastrocnemius muscle and L6 myoblasts. Expression of Cav3P104L in L6 myoblasts led to its targeting to the Golgi and loss of native Cav3 (>95%), including that associated with mitochondrial membranes. Cav3P104L reduced mitochondrial mass and induced fragmentation of the mitochondrial network that was associated with significant loss of proteins involved in mitochondrial biogenesis, respiration, morphology, and redox function [i.e. PGC1α, succinate dehyrdogenase (SDHA), ANT1, MFN2, OPA1, and MnSOD). Furthermore, Cav3P104L myoblasts exhibited increased mitochondrial cholesterol and loss of cardiolipin. Consistent with these changes, Cav3P104L expression reduced mitochondrial respiratory capacity and increased myocellular superoxide production. These morphological, biochemical, and functional mitochondrial changes were phenocopied in myoblasts in which Cav3 had been silenced/knocked-out using shRNA or CRISPR. Reduced mitochondrial mass, PGC1α, SDHA, ANT1, and MnSOD were also demonstrable in Cav3-/- mouse gastrocnemius. Strikingly, Cav3 re-expression in Cav3KO myoblasts restored its mitochondrial association and facilitated reformation of a tubular mitochondrial network. Significantly, re-expression also mitigated changes in mitochondrial superoxide, cholesterol, and cardiolipin content and recovered cellular respiratory capacity. CONCLUSIONS Our results identify Cav3 as an important regulator of mitochondrial homeostasis and reveal that Cav3 deficiency in muscle cells associated with the Cav3P104L mutation invokes major disturbances in mitochondrial respiration and energy status that may contribute to the pathology of LGMD1C.
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Affiliation(s)
- Dinesh S Shah
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK
| | - Raid B Nisr
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK
| | - Clare Stretton
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK
| | - Gabriela Krasteva-Christ
- Institute of Anatomy and Cell Biology, School of Medicine, Saarland University, Homburg, Germany
| | - Harinder S Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee, UK
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17
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Pol A, Morales-Paytuví F, Bosch M, Parton RG. Non-caveolar caveolins – duties outside the caves. J Cell Sci 2020; 133:133/9/jcs241562. [DOI: 10.1242/jcs.241562] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
ABSTRACT
Caveolae are invaginations of the plasma membrane that are remarkably abundant in adipocytes, endothelial cells and muscle. Caveolae provide cells with resources for mechanoprotection, can undergo fission from the plasma membrane and can regulate a variety of signaling pathways. Caveolins are fundamental components of caveolae, but many cells, such as hepatocytes and many neurons, express caveolins without forming distinguishable caveolae. Thus, the function of caveolins goes beyond their roles as caveolar components. The membrane-organizing and -sculpting capacities of caveolins, in combination with their complex intracellular trafficking, might contribute to these additional roles. Furthermore, non-caveolar caveolins can potentially interact with proteins normally excluded from caveolae. Here, we revisit the non-canonical roles of caveolins in a variety of cellular contexts including liver, brain, lymphocytes, cilia and cancer cells, as well as consider insights from invertebrate systems. Non-caveolar caveolins can determine the intracellular fluxes of active lipids, including cholesterol and sphingolipids. Accordingly, caveolins directly or remotely control a plethora of lipid-dependent processes such as the endocytosis of specific cargoes, sorting and transport in endocytic compartments, or different signaling pathways. Indeed, loss-of-function of non-caveolar caveolins might contribute to the common phenotypes and pathologies of caveolin-deficient cells and animals.
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Affiliation(s)
- Albert Pol
- Cell Compartments and Signaling Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, 08036, Barcelona, Spain
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, 08036, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010, Barcelona, Spain
| | - Frederic Morales-Paytuví
- Cell Compartments and Signaling Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, 08036, Barcelona, Spain
| | - Marta Bosch
- Cell Compartments and Signaling Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, 08036, Barcelona, Spain
- Department of Biomedical Sciences, Faculty of Medicine, Universitat de Barcelona, 08036, Barcelona, Spain
| | - Robert G. Parton
- Institute for Molecular Bioscience (IMB), The University of Queensland (UQ), Brisbane, Queensland 4072, Australia
- Centre for Microscopy and Microanalysis (CMM) IMB, The University of Queensland (UQ), Brisbane, Queensland 4072, Australia
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18
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Raudenska M, Gumulec J, Balvan J, Masarik M. Caveolin-1 in oncogenic metabolic symbiosis. Int J Cancer 2020; 147:1793-1807. [PMID: 32196654 DOI: 10.1002/ijc.32987] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/28/2020] [Accepted: 03/16/2020] [Indexed: 12/18/2022]
Abstract
Metabolic phenotypes of cancer cells are heterogeneous and flexible as a tumor mass is a hurriedly evolving system capable of constant adaptation to oxygen and nutrient availability. The exact type of cancer metabolism arises from the combined effects of factors intrinsic to the cancer cells and factors proposed by the tumor microenvironment. As a result, a condition termed oncogenic metabolic symbiosis in which components of the tumor microenvironment (TME) promote tumor growth often occurs. Understanding how oncogenic metabolic symbiosis emerges and evolves is crucial for perceiving tumorigenesis. The process by which tumor cells reprogram their TME involves many mechanisms, including changes in intercellular communication, alterations in metabolic phenotypes of TME cells, and rearrangement of the extracellular matrix. It is possible that one molecule with a pleiotropic effect such as Caveolin-1 may affect many of these pathways. Here, we discuss the significance of Caveolin-1 in establishing metabolic symbiosis in TME.
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Affiliation(s)
- Martina Raudenska
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Jaromir Gumulec
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Chemistry and Biochemistry, Mendel University in Brno, Brno, Czech Republic
| | - Jan Balvan
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Chemistry and Biochemistry, Mendel University in Brno, Brno, Czech Republic
| | - Michal Masarik
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,BIOCEV, First Faculty of Medicine, Charles University, Vestec, Czech Republic
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19
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Dumková J, Smutná T, Vrlíková L, Kotasová H, Dočekal B, Čapka L, Tvrdoňová M, Jakešová V, Pelková V, Křůmal K, Coufalík P, Mikuška P, Večeřa Z, Vaculovič T, Husáková Z, Kanický V, Hampl A, Buchtová M. Variability in the Clearance of Lead Oxide Nanoparticles Is Associated with Alteration of Specific Membrane Transporters. ACS NANO 2020; 14:3096-3120. [PMID: 32105447 DOI: 10.1021/acsnano.9b08143] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lead oxide nanoparticles (PbONPs), upon their entry into the lungs via inhalation, induce structural changes in primary and secondary target organs. The fate and ultrastructural localization of PbONPs in organs is known to be dependent on the specific organ. Here, we focused on the differences in the ability to clear the inhaled PbONPs from secondary target organs and on molecular and cellular mechanisms contributing to nanoparticle removal. Mice were exposed to PbONPs in whole-body inhalation chambers. Clearance of ionic lead and PbONPs (Pb/PbONPs) from the lungs and liver was very effective, with the lead being almost completely eliminated from the lungs and the physiological state of the lung tissue conspicuously restored. Kidneys exposed to nanoparticles did not exhibit serious signs of damage; however, LA-ICP-MS uncovered a certain amount of lead located preferentially in the kidney cortex even after a clearance period. The concentration of lead in femurs, as representatives of the axial skeleton, was the highest among studied organs at all designated time points after PbONP exposure, and the clearance ability of lead from the femurs was very low in contrast to other organs. The organ-specific increase of ABC transporters expression (ABCG2 in lungs and ABCC3 in the liver) was observed in exposed animals, suggesting their involvement in removing Pb/PbONPs from tissues. Moreover, the expression of caveolins and clathrin displayed a tissue-specific response to lead exposure. Our results uncovered high variability among the organs in their ability to clear Pb/PbONPs and in the transporters involved in this process.
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Affiliation(s)
- Jana Dumková
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno 625 00, Czech Republic
| | - Tereza Smutná
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno 625 00, Czech Republic
- Laboratory of Molecular Morphogenesis, Institute of Animal Physiology and Genetics, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Lucie Vrlíková
- Laboratory of Molecular Morphogenesis, Institute of Animal Physiology and Genetics, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Hana Kotasová
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno 625 00, Czech Republic
| | - Bohumil Dočekal
- Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Lukáš Čapka
- Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Michaela Tvrdoňová
- Department of Chemistry, Faculty of Science, Masaryk University, Brno 625 00, Czech Republic
| | - Veronika Jakešová
- Laboratory of Molecular Morphogenesis, Institute of Animal Physiology and Genetics, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Vendula Pelková
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno 625 00, Czech Republic
| | - Kamil Křůmal
- Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Pavel Coufalík
- Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Pavel Mikuška
- Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Zbyněk Večeřa
- Institute of Analytical Chemistry, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
| | - Tomáš Vaculovič
- Department of Chemistry, Faculty of Science, Masaryk University, Brno 625 00, Czech Republic
| | - Zuzana Husáková
- Department of Chemistry, Faculty of Science, Masaryk University, Brno 625 00, Czech Republic
| | - Viktor Kanický
- Department of Chemistry, Faculty of Science, Masaryk University, Brno 625 00, Czech Republic
| | - Aleš Hampl
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno 625 00, Czech Republic
| | - Marcela Buchtová
- Laboratory of Molecular Morphogenesis, Institute of Animal Physiology and Genetics, v.v.i., Czech Academy of Sciences, Brno 602 00, Czech Republic
- Section of Animal Physiology and Immunology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno 625 00, Czech Republic
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20
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Nguyen LP, Tran SC, Suetsugu S, Lim YS, Hwang SB. PACSIN2 Interacts with Nonstructural Protein 5A and Regulates Hepatitis C Virus Assembly. J Virol 2020; 94:e01531-19. [PMID: 31801866 PMCID: PMC7022371 DOI: 10.1128/jvi.01531-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 11/26/2019] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) is a major etiologic agent of chronic liver diseases. HCV is highly dependent on cellular machinery for viral propagation. Using protein microarray analysis, we previously identified 90 cellular proteins as nonstructural 5A (NS5A) interacting partners. Of these, protein kinase C and casein kinase substrate in neurons protein 2 (PACSIN2) was selected for further study. PACSIN2 belongs to the PACSIN family, which is involved in the formation of caveolae. Protein interaction between NS5A and PACSIN2 was confirmed by pulldown assay and further verified by both coimmunoprecipitation and immunofluorescence assays. We showed that PACSIN2 interacted with domain I of NS5A and the Fer-CIP4 homology (FCH)-Bin/amphiphysin/Rvs (F-BAR) region of PACSIN2. Interestingly, NS5A specifically attenuated protein kinase C alpha (PKCα)-mediated phosphorylation of PACSIN2 at serine 313 by interrupting PACSIN2 and PKCα interaction. In fact, mutation of the serine 313 to alanine (S313A) of PACSIN2 increased protein interaction with NS5A. Silencing of PACSIN2 decreased both viral RNA and protein expression levels of HCV. Ectopic expression of the small interfering RNA (siRNA)-resistant PACSIN2 recovered the viral infectivity, suggesting that PACSIN2 was specifically required for HCV propagation. PACSIN2 was involved in viral assembly without affecting other steps of the HCV life cycle. Indeed, overexpression of PACSIN2 promoted NS5A and core protein (core) interaction. We further showed that inhibition of PKCα increased NS5A and core interaction, suggesting that phosphorylation of PACSIN2 might influence HCV assembly. Moreover, PACSIN2 was required for lipid droplet formation via modulating extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Taken together, these data indicate that HCV modulates PACSIN2 via NS5A to promote virion assembly.IMPORTANCE PACSIN2 is a lipid-binding protein that triggers the tubulation of the phosphatidic acid-containing membranes. The functional involvement of PACSIN2 in the virus life cycle has not yet been demonstrated. We showed that phosphorylation of PACSIN2 displayed a negative effect on NS5A and core interaction. The most significant finding is that NS5A prevents PKCα from binding to PACSIN2. Therefore, the phosphorylation level of PACSIN2 is decreased in HCV-infected cells. We showed that HCV NS5A interrupted PKCα-mediated PACSIN2 phosphorylation at serine 313, thereby promoting NS5A-PACSIN2 interaction. We further demonstrated that PACSIN2 modulated lipid droplet formation through ERK1/2 phosphorylation. These data provide evidence that PACSIN2 is a proviral cellular factor required for viral propagation.
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Affiliation(s)
- Lap P Nguyen
- Laboratory of RNA Viral Diseases, Korea Zoonosis Research Institute, Chonbuk National University, Iksan, South Korea
- National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea
| | - Si C Tran
- National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea
| | - Shiro Suetsugu
- Laboratory of Molecular Medicine and Cell Biology, Graduate School of Biosciences, Nara Institute of Science and Technology, Ikoma, Japan
| | - Yun-Sook Lim
- Laboratory of RNA Viral Diseases, Korea Zoonosis Research Institute, Chonbuk National University, Iksan, South Korea
- National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea
| | - Soon B Hwang
- Laboratory of RNA Viral Diseases, Korea Zoonosis Research Institute, Chonbuk National University, Iksan, South Korea
- National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea
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21
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Filipović N, Bočina I, Restović I, Grobe M, Kretzschmar G, Kević N, Mašek T, Vitlov Uljević M, Jurić M, Vukojević K, Saraga-Babić M, Vuica A. Ultrastructural characterization of vitamin D receptors and metabolizing enzymes in the lipid droplets of the fatty liver in rat. Acta Histochem 2020; 122:151502. [PMID: 31932064 DOI: 10.1016/j.acthis.2020.151502] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 11/11/2019] [Accepted: 11/11/2019] [Indexed: 01/10/2023]
Abstract
Vitamin D is a steroid hormone with numerous actions in the organism. There are strong evidences that relate vitamin D deficiency with liver lipid metabolism disturbances, but the mechanism of this action is still unknown. In our previous work we postulated the localization and accumulation of vitamin D receptor (VDR) in membrane of the lipid droplets (LDs) in hepatocytes. In this study, we applied the transmission electron microscopy (TEM) to confirm this hypothesis by using a long-term (6 months) high sucrose intake rat model that was previously found to be appropriate for research of the hepatic lipid accumulation. In addition to the VDR, we also found key vitamin D metabolizing enzymes, 1α-hydroxylase and CYP 24 associated with the membrane of the LDs. A light-microscopy data revealed significant increase in expression of VDR and CYP 24 in liver of high-sucrose treated rats, in comparison to controlones. According to the best of our knowledge, this is a first study confirming the presence of the VDR in the membrane of the LDs in general and also in particular in LDs of the hepatocytes that were accumulated as a consequence of the prolonged high sucrose intake. Moreover, we found association of main vitamin D metabolizing enzymes with LD membrane. These results provide a new insight in the possible relation of vitamin D signalling system with LD morphology and function and with the lipid metabolism in general.
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22
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Egger AN, Rajabi‐Estarabadi A, Williams NM, Resnik SR, Fox JD, Wong LL, Jozic I. The importance of caveolins and caveolae to dermatology: Lessons from the caves and beyond. Exp Dermatol 2020; 29:136-148. [PMID: 31845391 PMCID: PMC7028117 DOI: 10.1111/exd.14068] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/25/2019] [Accepted: 11/28/2019] [Indexed: 12/15/2022]
Abstract
Caveolae are flask-shaped invaginations of the cell membrane rich in cholesterol and sphingomyelin, with caveolin proteins acting as their primary structural components that allow compartmentalization and orchestration of various signalling molecules. In this review, we discuss how pleiotropic functions of caveolin-1 (Cav1) and its intricate roles in numerous cellular functions including lipid trafficking, signalling, cell migration and proliferation, as well as cellular senescence, infection and inflammation, are integral for normal development and functioning of skin and its appendages. We then examine how disruption of the homeostatic levels of Cav1 can lead to development of various cutaneous pathophysiologies including skin cancers, cutaneous fibroses, psoriasis, alopecia, age-related changes in skin and aberrant wound healing and propose how levels of Cav1 may have theragnostic value in skin physiology/pathophysiology.
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Affiliation(s)
- Andjela N. Egger
- Wound Healing and Regenerative Medicine Research ProgramDr. Phillip Frost Department of Dermatology and Cutaneous SurgeryUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Ali Rajabi‐Estarabadi
- Wound Healing and Regenerative Medicine Research ProgramDr. Phillip Frost Department of Dermatology and Cutaneous SurgeryUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Natalie M. Williams
- Wound Healing and Regenerative Medicine Research ProgramDr. Phillip Frost Department of Dermatology and Cutaneous SurgeryUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Sydney R. Resnik
- Wound Healing and Regenerative Medicine Research ProgramDr. Phillip Frost Department of Dermatology and Cutaneous SurgeryUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Joshua D. Fox
- Wound Healing and Regenerative Medicine Research ProgramDr. Phillip Frost Department of Dermatology and Cutaneous SurgeryUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Lulu L. Wong
- Wound Healing and Regenerative Medicine Research ProgramDr. Phillip Frost Department of Dermatology and Cutaneous SurgeryUniversity of Miami Miller School of MedicineMiamiFLUSA
| | - Ivan Jozic
- Wound Healing and Regenerative Medicine Research ProgramDr. Phillip Frost Department of Dermatology and Cutaneous SurgeryUniversity of Miami Miller School of MedicineMiamiFLUSA
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23
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Zoni V, Nieto V, Endter LJ, Risselada HJ, Monticelli L, Vanni S. To Bud or Not to Bud: A Perspective on Molecular Simulations of Lipid Droplet Budding. Front Mol Biosci 2019; 6:124. [PMID: 31799255 PMCID: PMC6863888 DOI: 10.3389/fmolb.2019.00124] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/24/2019] [Indexed: 12/20/2022] Open
Affiliation(s)
- Valeria Zoni
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Vincent Nieto
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS, Universitè de Lyon, Lyon, France
| | - Laura J Endter
- Department of Theoretical Physics, Georg-August University Göttingen, Göttingen, Germany
| | - Herre J Risselada
- Department of Theoretical Physics, Georg-August University Göttingen, Göttingen, Germany
| | - Luca Monticelli
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS, Universitè de Lyon, Lyon, France
| | - Stefano Vanni
- Department of Biology, University of Fribourg, Fribourg, Switzerland.,CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Université Côte d'Azur, Valbonne, France
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24
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Chen Y, Frost S, Khushi M, Cantrill LC, Yu H, Arthur JW, Bright RK, Groblewski GE, Byrne JA. Delayed recruiting of TPD52 to lipid droplets - evidence for a "second wave" of lipid droplet-associated proteins that respond to altered lipid storage induced by Brefeldin A treatment. Sci Rep 2019; 9:9790. [PMID: 31278300 PMCID: PMC6611826 DOI: 10.1038/s41598-019-46156-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 06/18/2019] [Indexed: 12/27/2022] Open
Abstract
Tumor protein D52 (TPD52) is amplified and overexpressed in breast and prostate cancers which are frequently characterised by dysregulated lipid storage and metabolism. TPD52 expression increases lipid storage in mouse 3T3 fibroblasts, and co-distributes with the Golgi marker GM130 and lipid droplets (LDs). We examined the effects of Brefeldin A (BFA), a fungal metabolite known to disrupt the Golgi structure, in TPD52-expressing 3T3 cells, and in human AU565 and HMC-1-8 breast cancer cells that endogenously express TPD52. Five-hour BFA treatment reduced median LD numbers, but increased LD sizes. TPD52 knockdown decreased both LD sizes and numbers, and blunted BFA's effects on LD numbers. Following BFA treatment for 1-3 hours, TPD52 co-localised with the trans-Golgi network protein syntaxin 6, but after 5 hours BFA treatment, TPD52 showed increased co-localisation with LDs, which was disrupted by microtubule depolymerising agent nocodazole. BFA treatment also increased perilipin (PLIN) family protein PLIN3 but reduced PLIN2 detection at LDs in TPD52-expressing 3T3 cells, with PLIN3 recruitment to LDs preceding that of TPD52. An N-terminally deleted HA-TPD52 mutant (residues 40-184) almost exclusively targeted to LDs in both vehicle and BFA treated cells. In summary, delayed recruitment of TPD52 to LDs suggests that TPD52 participates in a temporal hierarchy of LD-associated proteins that responds to altered LD packaging requirements induced by BFA treatment.
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Affiliation(s)
- Yuyan Chen
- Molecular Oncology Laboratory, Children's Cancer Research Unit, Kids Research, The Children's Hospital at Westmead, Westmead, NSW, 2145, Australia.
- The University of Sydney Discipline of Child and Adolescent Health, The Children's Hospital at Westmead, Westmead, NSW, 2145, Australia.
| | - Sarah Frost
- Molecular Oncology Laboratory, Children's Cancer Research Unit, Kids Research, The Children's Hospital at Westmead, Westmead, NSW, 2145, Australia
- The University of Sydney Discipline of Child and Adolescent Health, The Children's Hospital at Westmead, Westmead, NSW, 2145, Australia
| | - Matloob Khushi
- Bioinformatics Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
- The University of Sydney School of Information Technologies, Darlington, NSW, 2008, Australia
| | - Laurence C Cantrill
- The University of Sydney Discipline of Child and Adolescent Health, The Children's Hospital at Westmead, Westmead, NSW, 2145, Australia
- Kids Research Microscope Facility, The Children's Hospital at Westmead, Westmead, NSW, 2145, Australia
| | - Hong Yu
- Cell Imaging Facility, Westmead Institute for Medical Research, Westmead, NSW, 2145, Australia
| | - Jonathan W Arthur
- Bioinformatics Unit, Children's Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
| | - Robert K Bright
- Department of Immunology and Molecular Microbiology and TTUHSC Cancer Center, Texas Tech University Health Sciences Center, Lubbock, Texas, 79430, USA
| | - Guy E Groblewski
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA
| | - Jennifer A Byrne
- Molecular Oncology Laboratory, Children's Cancer Research Unit, Kids Research, The Children's Hospital at Westmead, Westmead, NSW, 2145, Australia.
- The University of Sydney Discipline of Child and Adolescent Health, The Children's Hospital at Westmead, Westmead, NSW, 2145, Australia.
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25
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Chorlay A, Monticelli L, Veríssimo Ferreira J, Ben M'barek K, Ajjaji D, Wang S, Johnson E, Beck R, Omrane M, Beller M, Carvalho P, Rachid Thiam A. Membrane Asymmetry Imposes Directionality on Lipid Droplet Emergence from the ER. Dev Cell 2019; 50:25-42.e7. [PMID: 31155466 DOI: 10.1016/j.devcel.2019.05.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 01/11/2019] [Accepted: 05/02/2019] [Indexed: 01/18/2023]
Abstract
During energy bursts, neutral lipids fabricated within the ER bilayer demix to form lipid droplets (LDs). LDs bud off mainly in the cytosol where they regulate metabolism and multiple biological processes. They indeed become accessible to most enzymes and can interact with other organelles. How such directional emergence is achieved remains elusive. Here, we found that this directionality is controlled by an asymmetry in monolayer surface coverage. Model LDs emerge on the membrane leaflet of higher coverage, which is improved by the insertion of proteins and phospholipids. In cells, continuous LD emergence on the cytosol would require a constant refill of phospholipids to the ER cytosolic leaflet. Consistent with this model, cells deficient in phospholipids present an increased number of LDs exposed to the ER lumen and compensate by remodeling ER shape. Our results reveal an active cooperation between phospholipids and proteins to extract LDs from ER.
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Affiliation(s)
- Aymeric Chorlay
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Luca Monticelli
- Laboratory of Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS and University of Lyon, Lyon 69367, France
| | | | - Kalthoum Ben M'barek
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Dalila Ajjaji
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Sihui Wang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Errin Johnson
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Rainer Beck
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Mathias Beller
- Institute for Mathematical Modeling of Biological Systems, Systems Biology of Lipid Metabolism, Heinrich Heine University, Düsseldorf, Germany
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRSSorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.
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26
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Yokomori H, Ando W, Oda M. Caveolin-1 is related to lipid droplet formation in hepatic stellate cells in human liver. Acta Histochem 2019; 121:113-118. [PMID: 30446170 DOI: 10.1016/j.acthis.2018.10.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 10/19/2018] [Accepted: 10/19/2018] [Indexed: 11/30/2022]
Abstract
Caveolins (CAVs) regulate intracellular cholesterol transport by a complex process involving caveolae, endoplasmic reticulum (ER), and the Golgi network. Hepatic stellate cells (HSCs) are the central site for retinoid storage in the liver and indeed the entire body. Herein, we attempted to elucidate the ultrastructural localization and expression of caveolin-1 (CAV-1) in human HSCs during the progression of liver cirrhosis (LC). Normal and hepatitis C-related cirrhotic liver samples were prepared using a modified perfusion-fixation method to fix organelle structures and molecules in their in vivo positions, and examined using immunoelectron microscopy. In control liver specimens, CAV-1 was minimally associated with low electron density lipid droplets (LDs) segregated around zones 1-2, and specifically associated with membranes surrounding LDs. CAV-1 was segregated in high-density LDs, consistent with the formation of membrane-enclosed lipid-rich vesicular structures, as well as caveolae on plasma membranes around zones 2-3. In cirrhotic liver specimens, CAV-1 molecules were inserted into the cytoplasmic leaflets of ER membranes for transportation to LDs. Thus, CAV-1 transport to LDs might represent an intracellular pathway from the ER in cirrhotic liver tissue.
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Affiliation(s)
- Hiroaki Yokomori
- Department of Internal Medicine, Kitasato University Medical Center, Saitama, Japan.
| | - Wataru Ando
- Department of Clinical Pharmacy, School of Pharmacy, Kitasato University, Tokyo, Japan
| | - Masaya Oda
- Organized Center of Clinical Medicine, Sanno Medical Center, International University of Health and Welfare, Tokyo, Japan
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27
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Burke LC, Ezeribe HO, Kwon AY, Dockery D, Lyons PJ. Carboxypeptidase O is a lipid droplet-associated enzyme able to cleave both acidic and polar C-terminal amino acids. PLoS One 2018; 13:e0206824. [PMID: 30388170 PMCID: PMC6214572 DOI: 10.1371/journal.pone.0206824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 10/19/2018] [Indexed: 11/18/2022] Open
Abstract
Carboxypeptidase O (CPO) is a member of the M14 family of metallocarboxypeptidases with a preference for the cleavage of C-terminal acidic amino acids. CPO is largely expressed in the small intestine, although it has been detected in other tissues such as the brain and ovaries. CPO does not contain a prodomain, nor is it strongly regulated by pH, and hence appears to exist as a constitutively active enzyme. The goal of this study was to investigate the intracellular distribution and activity of CPO in order to predict physiological substrates and function. The distribution of CPO, when expressed in MDCK cells, was analyzed by immunofluorescence microscopy. Soon after addition of nutrient-rich media, CPO was found to associate with lipid droplets, causing an increase in lipid droplet quantity. As media became depleted, CPO moved to a broader ER distribution, no longer impacting lipid droplet numbers. Membrane cholesterol levels played a role in the distribution and in vitro enzymatic activity of CPO, with cholesterol enrichment leading to decreased lipid droplet association and enzymatic activity. The ability of CPO to cleave C-terminal amino acids within the early secretory pathway (in vivo) was examined using Gaussia luciferase as a substrate, C-terminally tagged with variants of an ER retention signal. While no effect of cholesterol was observed, these data show that CPO does function as an active enzyme within the ER where it removes C-terminal glutamates and aspartates, as well as a number of polar amino acids.
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Affiliation(s)
- Linnea C. Burke
- Department of Biology, Andrews University, Berrien Springs, Michigan, United States of America
| | - Hazel O. Ezeribe
- Department of Biology, Andrews University, Berrien Springs, Michigan, United States of America
| | - Anna Y. Kwon
- Department of Biology, Andrews University, Berrien Springs, Michigan, United States of America
| | - Donnel Dockery
- Department of Biology, Andrews University, Berrien Springs, Michigan, United States of America
| | - Peter J. Lyons
- Department of Biology, Andrews University, Berrien Springs, Michigan, United States of America
- * E-mail:
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28
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Affiliation(s)
- Saverio Cinti
- Professor of Human Anatomy, Director, Center of Obesity, University of Ancona (Politecnica delle Marche), Ancona, Italy
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29
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Pezeshkian W, Chevrot G, Khandelia H. The role of caveolin-1 in lipid droplets and their biogenesis. Chem Phys Lipids 2018; 211:93-99. [DOI: 10.1016/j.chemphyslip.2017.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 10/03/2017] [Accepted: 11/09/2017] [Indexed: 12/21/2022]
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30
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Abu-Taha IH, Heijman J, Feng Y, Vettel C, Dobrev D, Wieland T. Regulation of heterotrimeric G-protein signaling by NDPK/NME proteins and caveolins: an update. J Transl Med 2018; 98:190-197. [PMID: 29035382 DOI: 10.1038/labinvest.2017.103] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 07/17/2017] [Accepted: 07/31/2017] [Indexed: 12/14/2022] Open
Abstract
Heterotrimeric G proteins are pivotal mediators of cellular signal transduction in eukaryotic cells and abnormal G-protein signaling plays an important role in numerous diseases. During the last two decades it has become evident that the activation status of heterotrimeric G proteins is both highly localized and strongly regulated by a number of factors, including a receptor-independent activation pathway of heterotrimeric G proteins that does not involve the classical GDP/GTP exchange and relies on nucleoside diphosphate kinases (NDPKs). NDPKs are NTP/NDP transphosphorylases encoded by the nme/nm23 genes that are involved in a variety of cellular events such as proliferation, migration, and apoptosis. They therefore contribute, for example, to tumor metastasis, angiogenesis, retinopathy, and heart failure. Interestingly, NDPKs are translocated and/or upregulated in human heart failure. Here we describe recent advances in the current understanding of NDPK functions and how they have an impact on local regulation of G-protein signaling.
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Affiliation(s)
- Issam H Abu-Taha
- Institute of Pharmacology, West-German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Jordi Heijman
- Department of Cardiology, CARIM School for Cardiovascular Disease, Maastricht University, Maastricht, The Netherlands
| | - Yuxi Feng
- Institute of Experimental and Clinical Pharmacology and Toxicology, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany
| | - Christiane Vettel
- Institute of Experimental and Clinical Pharmacology and Toxicology, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, West-German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Thomas Wieland
- Institute of Experimental and Clinical Pharmacology and Toxicology, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, Germany
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31
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Abu-Taha IH, Heijman J, Feng Y, Vettel C, Dobrev D, Wieland T. Regulation of heterotrimeric G-protein signaling by NDPK/NME proteins and caveolins: an update. J Transl Med 2018. [PMID: 29035382 DOI: 10.38/labinvest.2017.103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023] Open
Abstract
Heterotrimeric G proteins are pivotal mediators of cellular signal transduction in eukaryotic cells and abnormal G-protein signaling plays an important role in numerous diseases. During the last two decades it has become evident that the activation status of heterotrimeric G proteins is both highly localized and strongly regulated by a number of factors, including a receptor-independent activation pathway of heterotrimeric G proteins that does not involve the classical GDP/GTP exchange and relies on nucleoside diphosphate kinases (NDPKs). NDPKs are NTP/NDP transphosphorylases encoded by the nme/nm23 genes that are involved in a variety of cellular events such as proliferation, migration, and apoptosis. They therefore contribute, for example, to tumor metastasis, angiogenesis, retinopathy, and heart failure. Interestingly, NDPKs are translocated and/or upregulated in human heart failure. Here we describe recent advances in the current understanding of NDPK functions and how they have an impact on local regulation of G-protein signaling.
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Affiliation(s)
- Issam H Abu-Taha
- Institute of Pharmacology, West-German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Jordi Heijman
- Department of Cardiology, CARIM School for Cardiovascular Disease, Maastricht University, Maastricht, The Netherlands
| | - Yuxi Feng
- Institute of Experimental and Clinical Pharmacology and Toxicology, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany
| | - Christiane Vettel
- Institute of Experimental and Clinical Pharmacology and Toxicology, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, West-German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Thomas Wieland
- Institute of Experimental and Clinical Pharmacology and Toxicology, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site, Heidelberg-Mannheim, Germany
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32
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Kuo A, Lee MY, Yang K, Gross RW, Sessa WC. Caveolin-1 regulates lipid droplet metabolism in endothelial cells via autocrine prostacyclin-stimulated, cAMP-mediated lipolysis. J Biol Chem 2017; 293:973-983. [PMID: 29203526 DOI: 10.1074/jbc.ra117.000980] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 11/28/2017] [Indexed: 11/06/2022] Open
Abstract
Lipid droplets (LD) are dynamic organelles involved in intracellular lipid metabolism in almost all eukaryotic cells, and LD-associated proteins tightly regulate their dynamics. One LD coat protein is caveolin-1 (Cav-1), an essential component for caveola assembly in highly differentiated cells, including adipocytes, smooth muscle cells, and endothelial cells (EC). However, the role of Cav-1 in LD dynamics is unclear. Here we report that EC lacking Cav-1 exhibit impaired LD formation. The decreased LD formation is due to enhanced lipolysis and not caused by reduced triglyceride synthesis or fatty acid uptake. Mechanistically, the absence of Cav-1 increased cAMP/PKA signaling in EC, as indicated by elevated phosphorylation of hormone-sensitive lipase and increased lipolysis. Unexpectedly, we also observed enhanced autocrine production of prostaglandin I2 (PGI2, also called prostacyclin) in Cav-1 KO EC, and this PGI2 increase appeared to stimulate cAMP/PKA pathways, contributing to the enhanced lipolysis in Cav-1 KO cells. Our results reveal an unanticipated role of Cav-1 in regulating lipolysis in non-adipose tissue, indicating that Cav-1 is required for LD metabolism in EC and that it regulates cAMP-dependent lipolysis in part via the autocrine production of PGI2.
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Affiliation(s)
- Andrew Kuo
- From the Vascular Biology and Therapeutics Program and.,Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510
| | - Monica Y Lee
- From the Vascular Biology and Therapeutics Program and.,Departments of Pharmacology and
| | - Kui Yang
- the Department of Medicine and Developmental Biology, Division of Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, and.,the Department of Chemistry, Washington University, St. Louis, Missouri 63130
| | - Richard W Gross
- the Department of Medicine and Developmental Biology, Division of Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, and.,the Department of Chemistry, Washington University, St. Louis, Missouri 63130
| | - William C Sessa
- From the Vascular Biology and Therapeutics Program and .,Departments of Pharmacology and
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33
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Copeland CA, Han B, Tiwari A, Austin ED, Loyd JE, West JD, Kenworthy AK. A disease-associated frameshift mutation in caveolin-1 disrupts caveolae formation and function through introduction of a de novo ER retention signal. Mol Biol Cell 2017; 28:3095-3111. [PMID: 28904206 PMCID: PMC5662265 DOI: 10.1091/mbc.e17-06-0421] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/30/2017] [Accepted: 09/06/2017] [Indexed: 02/07/2023] Open
Abstract
Heterozygous mutations in caveolin-1 (CAV1) have been linked to pulmonary arterial hypertension (PAH), but their impact on caveolae is unclear. We show that a PAH-associated frameshift mutation introduces an endoplasmic reticulum retention signal in CAV1 that partially disrupts caveolae assembly and interferes with their ability to serve as membrane buffers. Caveolin-1 (CAV1) is an essential component of caveolae and is implicated in numerous physiological processes. Recent studies have identified heterozygous mutations in the CAV1 gene in patients with pulmonary arterial hypertension (PAH), but the mechanisms by which these mutations impact caveolae assembly and contribute to disease remain unclear. To address this question, we examined the consequences of a familial PAH-associated frameshift mutation in CAV1, P158PfsX22, on caveolae assembly and function. We show that C-terminus of the CAV1 P158 protein contains a functional ER-retention signal that inhibits ER exit and caveolae formation and accelerates CAV1 turnover in Cav1–/– MEFs. Moreover, when coexpressed with wild-type (WT) CAV1 in Cav1–/– MEFs, CAV1-P158 functions as a dominant negative by partially disrupting WT CAV1 trafficking. In patient skin fibroblasts, CAV1 and caveolar accessory protein levels are reduced, fewer caveolae are observed, and CAV1 complexes exhibit biochemical abnormalities. Patient fibroblasts also exhibit decreased resistance to a hypo-osmotic challenge, suggesting the function of caveolae as membrane reservoir is compromised. We conclude that the P158PfsX22 frameshift introduces a gain of function that gives rise to a dominant negative form of CAV1, defining a new mechanism by which disease-associated mutations in CAV1 impair caveolae assembly.
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Affiliation(s)
- Courtney A. Copeland
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Bing Han
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Ajit Tiwari
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Eric D. Austin
- Department of Pediatrics, Vanderbilt University, Nashville, TN 37232
| | - James E. Loyd
- Department of Medicine, Vanderbilt University, Nashville, TN 37232
| | - James D. West
- Department of Medicine, Vanderbilt University, Nashville, TN 37232
| | - Anne K. Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
- Epithelial Biology Program, Vanderbilt University School of Medicine, Nashville, TN 37232
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN 37232
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34
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Schnitzler JG, Bernelot Moens SJ, Tiessens F, Bakker GJ, Dallinga-Thie GM, Groen AK, Nieuwdorp M, Stroes ESG, Kroon J. Nile Red Quantifier: a novel and quantitative tool to study lipid accumulation in patient-derived circulating monocytes using confocal microscopy. J Lipid Res 2017; 58:2210-2219. [PMID: 28972117 PMCID: PMC5665660 DOI: 10.1194/jlr.d073197] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 09/07/2017] [Indexed: 01/19/2023] Open
Abstract
The inflammatory profile of circulating monocytes is an important biomarker for atherosclerotic plaque vulnerability. Recent research revealed that peripheral lipid uptake by monocytes alters their phenotype toward an inflammatory state and this coincides with an increased lipid droplet (LD) content. Determination of lipid content of circulating monocytes is, however, not very well established. Based on Nile Red (NR) neutral LD imaging, using confocal microscopy and computational analysis, we developed NR Quantifier (NRQ), a novel quantification method to assess LD content in monocytes. Circulating monocytes were isolated from blood and used for the NR staining procedure. In monocytes stained with NR, we clearly distinguished, based on 3D imaging, phospholipids and exclusively intracellular neutral lipids. Next, we developed and validated NRQ, a semi-automated quantification program that detects alterations in lipid accumulation. NRQ was able to detect LD alterations after ex vivo exposure of isolated monocytes to freshly isolated LDL in a time- and dose-dependent fashion. Finally, we validated NRQ in patients with familial hypercholesterolemia and obese subjects in pre- and postprandial state. In conclusion, NRQ is a suitable tool to detect even small differences in neutral LD content in circulating monocytes using NR staining.
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Affiliation(s)
- Johan G Schnitzler
- Departments of Vascular Medicine University of Amsterdam, Amsterdam, The Netherlands
| | | | - Feiko Tiessens
- Departments of Vascular Medicine University of Amsterdam, Amsterdam, The Netherlands
| | - Guido J Bakker
- Departments of Vascular Medicine University of Amsterdam, Amsterdam, The Netherlands
| | - Geesje M Dallinga-Thie
- Departments of Vascular Medicine University of Amsterdam, Amsterdam, The Netherlands.,Experimental Vascular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Albert K Groen
- Departments of Vascular Medicine University of Amsterdam, Amsterdam, The Netherlands.,Department of Pediatrics, Laboratory of Metabolic Diseases, University of Groningen, University Medical Center Groningen (UMCG), Groningen, The Netherlands
| | - Max Nieuwdorp
- Departments of Vascular Medicine University of Amsterdam, Amsterdam, The Netherlands.,Wallenberg Laboratory, University of Gothenberg, Gothenberg, Sweden.,Department of Internal Medicine, Diabetes Center, Vrije Universiteit (VU) University Medical Center, Amsterdam, The Netherlands.,Institute for Cardiovascular Research, Vrije Universiteit (VU) University Medical Center, Amsterdam, The Netherlands
| | - Erik S G Stroes
- Departments of Vascular Medicine University of Amsterdam, Amsterdam, The Netherlands
| | - Jeffrey Kroon
- Departments of Vascular Medicine University of Amsterdam, Amsterdam, The Netherlands
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35
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Mohammadi S, Zakeri-Milani P, Golkar N, Farkhani SM, Shirani A, Shahbazi Mojarrad J, Nokhodchi A, Valizadeh H. Synthesis and cellular characterization of various nano-assemblies of cell penetrating peptide-epirubicin-polyglutamate conjugates for the enhancement of antitumor activity. ARTIFICIAL CELLS NANOMEDICINE AND BIOTECHNOLOGY 2017; 46:1572-1585. [PMID: 28933182 DOI: 10.1080/21691401.2017.1379016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A new class of cell penetrating peptides (CPPs) named peptide amphiphile was designed to improve the intracellular uptake and the antitumor activity of epirubicin (EPR). Various amphiphilic CPPs were synthesized by solid phase peptide synthesis method and were chemically conjugated to EPR. Their corresponding nanoparticles (CPPs-E4 and CPPs-E8) were prepared via non-covalent binding of the peptides and polyanions. Cytotoxicity and anti-proliferative activity were evaluated by MTT assay. Cellular uptake was examined by flow cytometry and fluorescence microscopy. The CPPs exhibited slight cytotoxicity. Binding of polyglutamate to CPPs (CPPs-E4 and CPPs-E8 nanoparticles) decreased their cytotoxicity. CPPs-E8 nanoparticles showed lower cytotoxicity than CPPs-E4 nanoparticles. Cellular uptake of K3W4K3-E8, K2W4K2-E8 and W3K4W3-E8 reached 100% with no difference between each of the mentioned CPPs and its nanoparticles at 50 µM. The anti-proliferative activity of EPR was enhanced following conjugation to peptides and nanoparticles at 25 µM. CPPs-EPR-E4 and CPPs-E8-EPR nanoparticles displayed higher anti-proliferative activity than CPPs-EPR at 25 µM. CPPs-E8-EPR nanoparticles showed higher anti-proliferative activity than CPPs-E4-EPR. K3W4K3-E8-EPR nanoparticles exhibited the highest anti-proliferative activity at 25 µM. The synthesized peptide nanoparticles are proposed as suitable carriers for improving the intracellular delivery of EPR into tumor cells with low cytotoxicity and high antitumor activity.
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Affiliation(s)
- Samaneh Mohammadi
- a Biotechnology Research Center and Faculty of Advanced Medical Sciences , Tabriz University of Medical Sciences , Tabriz , Iran
| | - Parvin Zakeri-Milani
- b Liver and Gastrointestinal Diseases Research Center and Faculty of Pharmacy , Tabriz University of Medical Sciences , Tabriz , Iran
| | - Nasim Golkar
- c Pharmaceutics Department, School of Pharmacy , Shiraz University of Medical Sciences , Shiraz , Iran
| | - Samad Mussa Farkhani
- a Biotechnology Research Center and Faculty of Advanced Medical Sciences , Tabriz University of Medical Sciences , Tabriz , Iran.,d Student Research Committee , Tabriz University of Medical Sciences , Tabriz , Iran
| | - Ali Shirani
- a Biotechnology Research Center and Faculty of Advanced Medical Sciences , Tabriz University of Medical Sciences , Tabriz , Iran.,d Student Research Committee , Tabriz University of Medical Sciences , Tabriz , Iran
| | - Javid Shahbazi Mojarrad
- b Liver and Gastrointestinal Diseases Research Center and Faculty of Pharmacy , Tabriz University of Medical Sciences , Tabriz , Iran
| | - Ali Nokhodchi
- e Pharmaceutics Research Laboratory, School of Life Sciences , University of Sussex , Brighton , UK
| | - Hadi Valizadeh
- f Drug Applied Research Center and Faculty of Pharmacy , Tabriz University of Medical Sciences , Tabriz , Iran
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Kimmel AR, Sztalryd C. The Perilipins: Major Cytosolic Lipid Droplet-Associated Proteins and Their Roles in Cellular Lipid Storage, Mobilization, and Systemic Homeostasis. Annu Rev Nutr 2017; 36:471-509. [PMID: 27431369 DOI: 10.1146/annurev-nutr-071813-105410] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The discovery by Dr. Constantine Londos of perilipin 1, the major scaffold protein at the surface of cytosolic lipid droplets in adipocytes, marked a fundamental conceptual change in the understanding of lipolytic regulation. Focus then shifted from the enzymatic activation of lipases to substrate accessibility, mediated by perilipin-dependent protein sequestration and recruitment. Consequently, the lipid droplet became recognized as a unique, metabolically active cellular organelle and its surface as the active site for novel protein-protein interactions. A new area of investigation emerged, centered on lipid droplets' biology and their role in energy homeostasis. The perilipin family is of ancient origin and has expanded to include five mammalian genes and a growing list of evolutionarily conserved members. Universally, the perilipins modulate cellular lipid storage. This review provides a summary that connects the perilipins to both cellular and whole-body homeostasis.
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Affiliation(s)
- Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, Maryland 20892;
| | - Carole Sztalryd
- The Geriatric Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, Baltimore, Maryland 21201.,Division of Endocrinology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland 21201;
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Alawin OA, Ahmed RA, Dronamraju V, Briski KP, Sylvester PW. γ-Tocotrienol-induced disruption of lipid rafts in human breast cancer cells is associated with a reduction in exosome heregulin content. J Nutr Biochem 2017; 48:83-93. [PMID: 28797930 DOI: 10.1016/j.jnutbio.2017.06.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 05/09/2017] [Accepted: 06/22/2017] [Indexed: 12/27/2022]
Abstract
Overexpression of heregulin, a potent ligand that activates HER3 and HER4 receptors, plays a significant role in the development of chemotherapy resistance in breast cancer patients. Exosomes released from cancer cells are small vesicles originating from the outward budding of lipid rafts that carry various mitogenic proteins that then act locally in an autocrine/paracrine manner to stimulate cancer cell growth. Since the anticancer activity of γ-tocotrienol has been shown to be mediated in part through the disruption of lipid rafts, studies were conducted to determine the effect of γ-tocotrienol on exosomes mitogenic biopotency. Exosomes isolated from the media of cultured T47D breast cancer cells were found to stimulate T47D cell growth in a dose-dependent manner. These growth stimulating effects were due to the high levels of heregulin contained in the exosomes that act to stimulate HER3 and HER4 activation, heterodimerization and mitogenic signaling. Exposure to 5 μM γ-tocotrienol resulted in the selective accumulation and disruption in the integrity of the lipid raft microdomain and a corresponding decrease in exosome heregulin content and mitogenic biopotency. These findings provide strong evidence indicating that the anticancer effects of γ-tocotrienol are mediated, at least in part, by directly disrupting HER dimerization and signaling within the lipid rafts and indirectly by reducing exosome heregulin content and subsequent autocrine/paracrine mitogenic stimulation.
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Affiliation(s)
- Osama A Alawin
- School of Pharmacy, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA
| | - Rayan A Ahmed
- School of Pharmacy, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA
| | | | - Karen P Briski
- School of Pharmacy, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA
| | - Paul W Sylvester
- School of Pharmacy, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA.
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Busija AR, Patel HH, Insel PA. Caveolins and cavins in the trafficking, maturation, and degradation of caveolae: implications for cell physiology. Am J Physiol Cell Physiol 2017; 312:C459-C477. [PMID: 28122734 DOI: 10.1152/ajpcell.00355.2016] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 01/09/2023]
Abstract
Caveolins (Cavs) are ~20 kDa scaffolding proteins that assemble as oligomeric complexes in lipid raft domains to form caveolae, flask-shaped plasma membrane (PM) invaginations. Caveolae ("little caves") require lipid-lipid, protein-lipid, and protein-protein interactions that can modulate the localization, conformational stability, ligand affinity, effector specificity, and other functions of proteins that are partners of Cavs. Cavs are assembled into small oligomers in the endoplasmic reticulum (ER), transported to the Golgi for assembly with cholesterol and other oligomers, and then exported to the PM as an intact coat complex. At the PM, cavins, ~50 kDa adapter proteins, oligomerize into an outer coat complex that remodels the membrane into caveolae. The structure of caveolae protects their contents (i.e., lipids and proteins) from degradation. Cellular changes, including signal transduction effects, can destabilize caveolae and produce cavin dissociation, restructuring of Cav oligomers, ubiquitination, internalization, and degradation. In this review, we provide a perspective of the life cycle (biogenesis, degradation), composition, and physiologic roles of Cavs and caveolae and identify unanswered questions regarding the roles of Cavs and cavins in caveolae and in regulating cell physiology.1.
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Affiliation(s)
- Anna R Busija
- Department of Anesthesiology, University of California, San Diego, La Jolla, California.,Department of Pharmacology, University of California, San Diego, La Jolla, California
| | - Hemal H Patel
- Department of Anesthesiology, University of California, San Diego, La Jolla, California
| | - Paul A Insel
- Department of Medicine, University of California, San Diego, La Jolla, California; and .,Department of Pharmacology, University of California, San Diego, La Jolla, California
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Listenberger LL, Studer AM, Brown DA, Wolins NE. Fluorescent Detection of Lipid Droplets and Associated Proteins. ACTA ACUST UNITED AC 2016; 71:4.31.1-4.31.14. [PMID: 27245427 DOI: 10.1002/cpcb.7] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Excess lipid is stored in intracellular organelles known as lipid droplets. This unit discusses techniques for the visualization of lipid droplets and associated proteins in cultured mammalian cells. Protocols for the detection of lipid droplets in fixed or live cells with BODIPY 493/503 are included. The best method for combining visualization of intracellular lipid droplets with indirect immunofluorescent detection of lipid droplet-associated proteins is described. Techniques for sample fixation and permeabilization must be chosen carefully to avoid alterations to lipid droplet morphology. Immunofluorescent detection of perilipin 2, a broadly expressed, lipid droplet-associated protein, widely used as a marker for lipid droplet accumulation, is presented as an example. Finally, a simple protocol for enhancing lipid droplet accumulation through supplementation with excess fatty acid is included. © 2016 by John Wiley & Sons, Inc.
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Affiliation(s)
| | - Andrea M Studer
- Departments of Biology and Chemistry, St. Olaf College, Northfield, Minnesota
| | - Deborah A Brown
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York
| | - Nathan E Wolins
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri
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The HSP70 co-chaperone DNAJC14 targets misfolded pendrin for unconventional protein secretion. Nat Commun 2016; 7:11386. [PMID: 27109633 PMCID: PMC4848490 DOI: 10.1038/ncomms11386] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 03/18/2016] [Indexed: 12/19/2022] Open
Abstract
Mutations in SLC26A4, which encodes pendrin, are responsible for hearing loss with an enlarged vestibular aqueduct and Pendred syndrome. The most prevalent mutation in East Asia is p.H723R (His723Arg), which leads to defects in protein folding and cell-surface expression. Here we show that H723R-pendrin can be rescued to the cell surface by an HSP70 co-chaperone DNAJC14-dependent unconventional trafficking pathway. Blockade of ER-to-Golgi transport or activation of ER stress signals induced Golgi-independent cell-surface expression of H723R-pendrin and restored its cell-surface Cl−/HCO3− exchange activity. Proteomic and short interfering RNA screenings with subsequent molecular analyses showed that Hsc70 and DNAJC14 are required for the unconventional trafficking of H723R-pendrin. Moreover, DNAJC14 upregulation was able to induce the unconventional cell-surface expression of H723R-pendrin. These results indicate that Hsc70 and DNAJC14 play central roles in ER stress-associated unconventional protein secretion and are potential therapeutic targets for diseases such as Pendred syndrome, which arise from transport defects of misfolded proteins. Mutations in pendrin, a plasma membrane transporter, lead to Pendred syndrome, which is associated with hearing loss. Here, Jung et al. show that cell-surface expression of a mutated form of pendrin can be restored by blocking ER-to-Golgi traffic and triggering a DNAJC14 dependent unconventional secretion pathway.
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Reinier F, Zoledziewska M, Hanna D, Smith JD, Valentini M, Zara I, Berutti R, Sanna S, Oppo M, Cusano R, Satta R, Montesu MA, Jones C, Cerimele D, Nickerson DA, Angius A, Cucca F, Cottoni F, Crisponi L. Mandibular hypoplasia, deafness, progeroid features and lipodystrophy (MDPL) syndrome in the context of inherited lipodystrophies. Metabolism 2015; 64:1530-40. [PMID: 26350127 DOI: 10.1016/j.metabol.2015.07.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 07/10/2015] [Accepted: 07/23/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND Lipodystrophies are a large heterogeneous group of genetic or acquired disorders characterized by generalized or partial fat loss, usually associated with metabolic complications such as diabetes mellitus, hypertriglyceridemia and hepatic steatosis. Many efforts have been made in the last years in identifying the genetic etiologies of several lipodystrophy forms, although some remain to be elucidated. METHODS We report here the clinical description of a woman with a rare severe lipodystrophic and progeroid syndrome associated with hypertriglyceridemia and diabetes whose genetic bases have been clarified through whole-exome sequencing (WES) analysis. RESULTS This article reports the 5th MDPL (Mandibular hypoplasia, deafness, progeroid features, and lipodystrophy syndrome) patient with the same de novo p.S605del mutation in POLD1. We provided further genetic evidence that this is a disease-causing mutation along with a plausible molecular mechanism responsible for this recurring event. Moreover we overviewed the current classification of the inherited forms of lipodystrophy, along with their underlying molecular basis. CONCLUSIONS Progress in the identification of lipodystrophy genes will help in better understanding the role of the pathways involved in the complex physiology of fat. This will lead to new targets towards develop innovative therapeutic strategies for treating the disorder and its metabolic complications, as well as more common forms of adipose tissue redistribution as observed in the metabolic syndrome and type 2 diabetes.
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Affiliation(s)
- Frederic Reinier
- Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy; Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Magdalena Zoledziewska
- Istituto di Ricerca Genetica e Biomedica (IRGB), Consiglio Nazionale delle Ricerche (CNR), Monserrato, Italy
| | - David Hanna
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Josh D Smith
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Maria Valentini
- Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy
| | - Ilenia Zara
- Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy
| | - Riccardo Berutti
- Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy
| | - Serena Sanna
- Istituto di Ricerca Genetica e Biomedica (IRGB), Consiglio Nazionale delle Ricerche (CNR), Monserrato, Italy
| | - Manuela Oppo
- Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy; Dipartimento di Scienze Biomediche, Università di Sassari, Sassari, Italy
| | - Roberto Cusano
- Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy
| | - Rosanna Satta
- Dipartimento di Scienze Chirurgiche, Microchirurgiche e Mediche-Dermatologia-Università di Sassari, Italy
| | - Maria Antonietta Montesu
- Dipartimento di Scienze Chirurgiche, Microchirurgiche e Mediche-Dermatologia-Università di Sassari, Italy
| | - Chris Jones
- Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy
| | - Decio Cerimele
- Dipartimento di Scienze Chirurgiche, Microchirurgiche e Mediche-Dermatologia-Università di Sassari, Italy
| | | | - Andrea Angius
- Centre for Advanced Studies, Research and Development in Sardinia (CRS4), Pula, Italy; Istituto di Ricerca Genetica e Biomedica (IRGB), Consiglio Nazionale delle Ricerche (CNR), Monserrato, Italy
| | - Francesco Cucca
- Istituto di Ricerca Genetica e Biomedica (IRGB), Consiglio Nazionale delle Ricerche (CNR), Monserrato, Italy; Dipartimento di Scienze Biomediche, Università di Sassari, Sassari, Italy
| | - Francesca Cottoni
- Dipartimento di Scienze Chirurgiche, Microchirurgiche e Mediche-Dermatologia-Università di Sassari, Italy
| | - Laura Crisponi
- Istituto di Ricerca Genetica e Biomedica (IRGB), Consiglio Nazionale delle Ricerche (CNR), Monserrato, Italy.
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Wang CW. Lipid droplet dynamics in budding yeast. Cell Mol Life Sci 2015; 72:2677-95. [PMID: 25894691 PMCID: PMC11113813 DOI: 10.1007/s00018-015-1903-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/01/2015] [Accepted: 04/07/2015] [Indexed: 10/23/2022]
Abstract
Eukaryotic cells store excess fatty acids as neutral lipids, predominantly triacylglycerols and sterol esters, in organelles termed lipid droplets (LDs) that bulge out from the endoplasmic reticulum. LDs are highly dynamic and contribute to diverse cellular functions. The catabolism of the storage lipids within LDs is channeled to multiple metabolic pathways, providing molecules for energy production, membrane building blocks, and lipid signaling. LDs have been implicated in a number of protein degradation and pathogen infection processes. LDs may be linked to prevalent human metabolic diseases and have marked potential for biofuel production. The knowledge accumulated on LDs in recent years provides a foundation for diverse, and even unexpected, future research. This review focuses on recent advances in LD research, emphasizing the diverse physiological roles of LDs in the model system of budding yeast.
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Affiliation(s)
- Chao-Wen Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan,
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Mest and Sfrp5 are biomarkers for healthy adipose tissue. Biochimie 2015; 124:124-133. [PMID: 26001362 DOI: 10.1016/j.biochi.2015.05.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/09/2015] [Indexed: 01/17/2023]
Abstract
Obesity depends on a close interplay between genetic and environmental factors. However, it is unknown how these factors interact to cause changes in the obese condition during the progression of obesity from the neonatal to the aged individual. We have utilized Mest and Sfrp5 genes, two genes highly correlated with adipose tissue expansion in diet-induced obesity, to characterize the obese condition during development of 2 genetic models of obesity. A model for the early onset of obesity was presented by leptin-deficient mice (ob/ob), whereas late onset of obesity was induced with high-fat diet (HFD) consumption in C57BL/6J mice with inherent risk of obesity (DIO). We correlated obese and diabetic phenotypes with Mest and Sfrp5 gene expression profiles in subcutaneous fat during pre-weaning, pre-adulthood and adulthood. A rapid development of obesity began in ob/ob mice immediately after weaning at 21 days of age, whereas the obesity of DIO mice was not evident until after 2 months of age. Even after 5 months of HFD treatment, the adiposity index of DIO mice was lower than in ob/ob mice at 2 months of age. In both obesity models, the expression of Mest and Sfrp5 genes increased in parallel with fat mass expansion; however, gene expression proceeded to decrease when the adiposity reached a plateau. The reduction in the expression of genes of caveolae structure and glucose metabolism were also suppressed in the aging adipose tissue. The analysis of fat mass and adipocyte size suggests that reduction in Mest and Sfrp5 is more sensitive to the age of the fat than its morphology. The balance of factors controlling fat deposition can be evaluated in part by the differential expression profiles of Mest and Sfrp5 genes with functions linked to fat deposition as long as there is an active accumulation of fat mass.
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Mulumba M, Granata R, Marleau S, Ong H. QRFP-43 inhibits lipolysis by preventing ligand-induced complex formation between perilipin A, caveolin-1, the catalytic subunit of protein kinase and hormone-sensitive lipase in 3T3-L1 adipocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:657-66. [PMID: 25677823 DOI: 10.1016/j.bbalip.2015.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 01/21/2015] [Accepted: 02/02/2015] [Indexed: 11/30/2022]
Abstract
QRFP (RFamide) peptides are neuropeptides involved in food intake and adiposity regulation in rodents. We have previously shown that QRFP-43 (43RFa) and QRFP-26 (26RFa) inhibited isoproterenol (ISO)-induced lipolysis in adipocytes. However, the antilipolytic signaling pathways activated by QRFP peptides have not been investigated. In the present study, 3T3-L1 adipocytes were used to identify the main pathways involved in QRFP-43 decreasing ISO-induced lipolysis. Our results show that QRFP-43 reduced ISO-induced phosphorylation of perilipin A (PLIN) and hormone-sensitive lipase (HSL) on Ser660 by 43 and 25%, respectively, but increased Akt phosphorylation by 44%. However, the inhibition of phosphodiesterase 3B (PDE3B), a regulator of lipolysis activated by Akt, did not reverse the antilipolytic effect of QRFP-43. PDE3B inhibition reversed the decrease of Ser660 HSL phosphorylation associated with QRFP-43 antilipolytic effect. QRFP-43 also prevented PKC activation and ISO-induced Src kinases activation leading to the inhibition of the caveolin-1 (CAV-1) translocation on lipid droplets. Indeed, QRFP-43 attenuated phorbol 12-myristate 13-acetate-induced lipolysis and ISO-induced extracellular signal-regulated and Src kinases by 28, 37 and 48%, respectively. The attenuation of ISO-induced lipolysis by QRFP-43 was associated with a decrease of phosphorylated Ser660 HSL, PKA-catalytic (PKA-c) subunit and CAV-1 translocation on lipid droplets by 37, 50 and 46%, respectively. The decrease in ISO-induced CAV-1 and PKA-c translocation was associated with a reduction of PLIN phosphorylation by 44% in QRFP-43-treated adipocytes. These results suggest that QRFP-43 attenuated ISO-induced lipolysis by preventing the formation of an active complex on lipid droplets and the activation of Src kinases and PKC.
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Affiliation(s)
- Mukandila Mulumba
- Faculty of Pharmacy, Université de Montréal C.P. 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada
| | - Riccarda Granata
- Laboratory of Molecular and Cellular Endocrinology, Department of Medical Sciences, University of Turin, Corso Dogliotti 14, Turin 10126, Italy
| | - Sylvie Marleau
- Faculty of Pharmacy, Université de Montréal C.P. 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada
| | - Huy Ong
- Faculty of Pharmacy, Université de Montréal C.P. 6128, Succursale Centre-Ville, Montréal, Québec H3C 3J7, Canada.
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46
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Aksanov O, Green P, Birk RZ. BBS4 directly affects proliferation and differentiation of adipocytes. Cell Mol Life Sci 2014; 71:3381-92. [PMID: 24500759 PMCID: PMC11113930 DOI: 10.1007/s00018-014-1571-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 01/17/2014] [Accepted: 01/20/2014] [Indexed: 12/23/2022]
Abstract
BBS4 is one of several proteins whose defects cause Bardet-Biedl syndrome (BBS), a multi-systemic disorder, manifesting with marked obesity. BBS4 polymorphisms have been associated with common non-syndromic morbid obesity. BBS4 obesity molecular mechanisms, and the role of the BBS4 gene in adipocyte differentiation and function are not entirely known. We now show that Bbs4 plays a direct and essential role in proliferation and adipogenesis: silencing of Bbs4 in 3T3F442A preadipocytes induced accelerated cell division and aberrant differentiation, evident through morphologic studies (light, scanning and transmission electron microscopy), metabolic analyses (fat accumulation, fatty acid profile and lipolysis) and adipogenic markers transcripts (Cebpα, Pparγ, aP2, ADRP, Perilipin). Throughout adipogenesis and when challenged with fat load, Bbs4 silenced cells accumulate significantly more triglycerides than control adipocytes, albeit in smaller (yet greater in number) droplets containing modified fatty acid profiles. Thus, greater fat accumulation in the silenced cells is a consequence of both a higher rate of adipocyte proliferation and of aberrant differentiation leading to augmented aberrant accumulation of fat per cell. Our findings suggest that the BBS obesity might be partly due to a direct role of BBS4 in physiological and pathophysiological mechanisms that underlie adipose tissue formation relevant to obesity.
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Affiliation(s)
- Olga Aksanov
- National Institute for Biotechnology in the Negev, Ben Gurion University, Beer-Sheva, Israel
| | - Pnina Green
- Laboratory for the Study of Fatty Acids, Felsenstein Medical Research Center, Beilinson Campus, Petah Tikva, the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ruth Z. Birk
- Department of Nutrition, Faculty of Health Science, Ariel University, Ariel, Israel
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Fridolfsson HN, Roth DM, Insel PA, Patel HH. Regulation of intracellular signaling and function by caveolin. FASEB J 2014; 28:3823-31. [PMID: 24858278 DOI: 10.1096/fj.14-252320] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 05/12/2014] [Indexed: 12/28/2022]
Abstract
Caveolae, flask-like invaginations of the plasma membrane, were discovered nearly 60 years ago. Originally regarded as fixation artifacts of electron microscopy, the functional role for these structures has taken decades to unravel. The discovery of the caveolin protein in 1992 (by the late Richard G.W. Anderson) accelerated progress in defining the contribution of caveolae to cellular physiology and pathophysiology. The three isoforms of caveolin (caveolin-1, -2, and -3) are caveolae-resident structural and scaffolding proteins that are critical for the formation of caveolae and their localization of signaling entities. A PubMed search for "caveolae" reveals ∼280 publications from their discovery in the 1950s to the early 1990s, whereas a search for "caveolae or caveolin" after 1990, identifies ∼7000 entries. Most work on the regulation of biological responses by caveolae and caveolin since 1990 has focused on caveolae as plasma membrane microdomains and the function of caveolin proteins at the plasma membrane. By contrast, our recent work and that of others has explored the localization of caveolins in multiple cellular membrane compartments and in the regulation of intracellular signaling. Cellular organelles that contain caveolin include mitochondria, nuclei and the endoplasmic reticulum. Such intracellular localization allows for a complexity of responses to extracellular stimuli by caveolin and the possibility of novel organelle-targeted therapeutics. This review focuses on the impact of intracellular localization of caveolin on signal transduction and cell regulation.
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Affiliation(s)
- Heidi N Fridolfsson
- VA San Diego Healthcare System, San Diego, California and the Departments of Anesthesiology
| | - David M Roth
- VA San Diego Healthcare System, San Diego, California and the Departments of Anesthesiology
| | - Paul A Insel
- Medicine, and Pharmacology, University of California San Diego, La Jolla, California
| | - Hemal H Patel
- VA San Diego Healthcare System, San Diego, California and the Departments of Anesthesiology,
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Minakshi R, Padhan K. The YXXΦ motif within the severe acute respiratory syndrome coronavirus (SARS-CoV) 3a protein is crucial for its intracellular transport. Virol J 2014; 11:75. [PMID: 24762043 PMCID: PMC4004515 DOI: 10.1186/1743-422x-11-75] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 04/04/2014] [Indexed: 12/04/2022] Open
Abstract
Background The SARS coronavirus (SARS-CoV) 3a protein functions as an ion channel, induces apoptosis and is important for viral pathogenesis. It is expressed on the cell surface and contains a tyrosine-based sorting motif and a di-acidic motif, which may be crucial for its intracellular trafficking. However the role of these motifs is not fully understood in the case of 3a protein. Methods The subcellular distribution of the 3a protein was studied by immunofluorescence staining of cells transfected with wild type and mutant constructs along with markers for different intracellular compartments. Semi-quantitative RT-PCR was performed to estimate the mRNA where as western blotting was carried out to detect protein levels of wild type and mutant 3a proteins. In vitro transcription- translation was performed to estimate cell free protein synthesis. Results While the wild type 3a protein is efficiently transported to the plasma membrane, the protein with mutations in the tyrosine and valine residues within the YXXV motif (ΔYXXΦ) accumulated in the Golgi compartment. However the 3a protein with mutations within the EXD di-acidic motif (ΔEXD) showed an intracellular distribution similar to the wild type protein. Increased retention of the ΔYXXΦ protein in the Golgi compartment also increased its association with lipid droplets. The ΔYXXΦ protein also expressed at significantly lower levels compared to the wild type 3a protein, which was reversed with Brefeldin A and Aprotinin. Conclusions The data suggest that the YXXΦ motif of the SARS-CoV 3a protein is necessary for Golgi to plasma membrane transport, in the absence of which the protein is targeted to lysosomal degradation compartment via lipid droplets.
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Affiliation(s)
| | - Kartika Padhan
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
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Paul LK, Rinne PLH, van der Schoot C. Refurbishing the plasmodesmal chamber: a role for lipid bodies? FRONTIERS IN PLANT SCIENCE 2014; 5:40. [PMID: 24605115 PMCID: PMC3932414 DOI: 10.3389/fpls.2014.00040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 01/28/2014] [Indexed: 05/04/2023]
Abstract
Lipid bodies (LBs) are universal constituents of both animal and plant cells. They are produced by specialized membrane domains at the tubular endoplasmic reticulum (ER), and consist of a core of neutral lipids and a surrounding monolayer of phospholipid with embedded amphipathic proteins. Although originally regarded as simple depots for lipids, they have recently emerged as organelles that interact with other cellular constituents, exchanging lipids, proteins and signaling molecules, and shuttling them between various intracellular destinations, including the plasmamembrane (PM). Recent data showed that in plants LBs can deliver a subset of 1,3-β-glucanases to the plasmodesmal (PD) channel. We hypothesize that this may represent a more general mechanism, which complements the delivery of glycosylphosphatidylinositol (GPI)-anchored proteins to the PD exterior via the secretory pathway. We propose that LBs may contribute to the maintenance of the PD chamber and the delivery of regulatory molecules as well as proteins destined for transport to adjacent cells. In addition, we speculate that LBs deliver their cargo through interaction with membrane domains in the cytofacial side of the PM.
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Affiliation(s)
| | | | - Christiaan van der Schoot
- *Correspondence: Christiaan van der Schoot, Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 1432, Ås, Norway e-mail:
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Vatier C, Bidault G, Briand N, Guénantin AC, Teyssières L, Lascols O, Capeau J, Vigouroux C. What the genetics of lipodystrophy can teach us about insulin resistance and diabetes. Curr Diab Rep 2013; 13:757-67. [PMID: 24026869 DOI: 10.1007/s11892-013-0431-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Genetic lipodystrophic syndromes are rare diseases characterized by generalized or partial fat atrophy (lipoatrophy) associated with severe metabolic complications such as insulin resistance (IR), diabetes, dyslipidemia, nonalcoholic fatty liver disease, and ovarian hyperandrogenism. During the last 15 years, mutations in several genes have been shown to be responsible for monogenic forms of lipodystrophic syndromes, of autosomal dominant or recessive transmission. Although the molecular basis of lipodystrophies is heterogeneous, most mutated genes lead to impaired adipogenesis, adipocyte lipid storage, and/or formation or maintenance of the adipocyte lipid droplet (LD), showing that primary alterations of adipose tissue (AT) can result in severe systemic metabolic and endocrine consequences. The reduced expandability of AT alters its ability to buffer excess caloric intake, leading to ectopic lipid storage that impairs insulin signaling and other cellular functions ("lipotoxicity"). Genetic studies have also pointed out the close relationships between ageing, inflammatory processes, lipodystrophy, and IR.
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Affiliation(s)
- Camille Vatier
- INSERM UMR_S938, Centre de Recherche Saint-Antoine, 75012, Paris, France
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