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Campos M, Albrecht LV. Hitting the Sweet Spot: How Glucose Metabolism Is Orchestrated in Space and Time by Phosphofructokinase-1. Cancers (Basel) 2023; 16:16. [PMID: 38201444 PMCID: PMC10778546 DOI: 10.3390/cancers16010016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/12/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
Glycolysis is the central metabolic pathway across all kingdoms of life. Intensive research efforts have been devoted to understanding the tightly orchestrated processes of converting glucose into energy in health and disease. Our review highlights the advances in knowledge of how metabolic and gene networks are integrated through the precise spatiotemporal compartmentalization of rate-limiting enzymes. We provide an overview of technically innovative approaches that have been applied to study phosphofructokinase-1 (PFK1), which represents the fate-determining step of oxidative glucose metabolism. Specifically, we discuss fast-acting chemical biology and optogenetic tools that have delineated new links between metabolite fluxes and transcriptional reprogramming, which operate together to enact tissue-specific processes. Finally, we discuss how recent paradigm-shifting insights into the fundamental basis of glycolytic regulatory control have shed light on the mechanisms of tumorigenesis and could provide insight into new therapeutic vulnerabilities in cancer.
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Affiliation(s)
- Melissa Campos
- Department of Developmental and Cell Biology, School of Biological Sciences, University of California, Irvine, CA 92697, USA;
| | - Lauren V. Albrecht
- Department of Developmental and Cell Biology, School of Biological Sciences, University of California, Irvine, CA 92697, USA;
- Department of Pharmaceutical Sciences, School of Pharmacy & Pharmaceutical Sciences, University of California, Irvine, CA 92697, USA
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2
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A Role for Caveolin-3 in the Pathogenesis of Muscular Dystrophies. Int J Mol Sci 2020; 21:ijms21228736. [PMID: 33228026 PMCID: PMC7699313 DOI: 10.3390/ijms21228736] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 12/14/2022] Open
Abstract
Caveolae are the cholesterol-rich small invaginations of the plasma membrane present in many cell types including adipocytes, endothelial cells, epithelial cells, fibroblasts, smooth muscles, skeletal muscles and cardiac muscles. They serve as specialized platforms for many signaling molecules and regulate important cellular processes like energy metabolism, lipid metabolism, mitochondria homeostasis, and mechano-transduction. Caveolae can be internalized together with associated cargo. The caveolae-dependent endocytic pathway plays a role in the withdrawal of many plasma membrane components that can be sent for degradation or recycled back to the cell surface. Caveolae are formed by oligomerization of caveolin proteins. Caveolin-3 is a muscle-specific isoform, whose malfunction is associated with several diseases including diabetes, cancer, atherosclerosis, and cardiovascular diseases. Mutations in Caveolin-3 are known to cause muscular dystrophies that are collectively called caveolinopathies. Altered expression of Caveolin-3 is also observed in Duchenne’s muscular dystrophy, which is likely a part of the pathological process leading to muscle weakness. This review summarizes the major functions of Caveolin-3 in skeletal muscles and discusses its involvement in the pathology of muscular dystrophies.
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Dudãu M, Codrici E, Tanase C, Gherghiceanu M, Enciu AM, Hinescu ME. Caveolae as Potential Hijackable Gates in Cell Communication. Front Cell Dev Biol 2020; 8:581732. [PMID: 33195223 PMCID: PMC7652756 DOI: 10.3389/fcell.2020.581732] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/08/2020] [Indexed: 12/16/2022] Open
Abstract
Caveolae are membrane microdomains described in many cell types involved in endocytocis, transcytosis, cell signaling, mechanotransduction, and aging. They are found at the interface with the extracellular environment and are structured by caveolin and cavin proteins. Caveolae and caveolins mediate transduction of chemical messages via signaling pathways, as well as non-chemical messages, such as stretching or shear stress. Various pathogens or signals can hijack these gates, leading to infectious, oncogenic and even caveolin-related diseases named caveolinopathies. By contrast, preclinical and clinical research have fallen behind in their attempts to hijack caveolae and caveolins for therapeutic purposes. Caveolae involvement in human disease is not yet fully explored or understood and, of all their scaffold proteins, only caveolin-1 is being considered in clinical trials as a possible biomarker of disease. This review briefly summarizes current knowledge about caveolae cell signaling and raises the hypothesis whether these microdomains could serve as hijackable “gatekeepers” or “gateways” in cell communication. Furthermore, because cell signaling is one of the most dynamic domains in translating data from basic to clinical research, we pay special attention to translation of caveolae, caveolin, and cavin research into clinical practice.
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Affiliation(s)
- Maria Dudãu
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Cell Biology and Histology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Elena Codrici
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania
| | - Cristiana Tanase
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Clinical Biochemistry Department, Faculty of Medicine, Titu Maiorescu University, Bucharest, Romania
| | - Mihaela Gherghiceanu
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Cell Biology and Histology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Ana-Maria Enciu
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Cell Biology and Histology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Mihail E Hinescu
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Cell Biology and Histology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
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Zhang Y, Fan W, Wu J, Dong J, Cui Z. Association of caveolin-1 protein expression with hepatocellular carcinoma: a meta-analysis and literature review. Cancer Manag Res 2019; 11:5113-5122. [PMID: 31239768 PMCID: PMC6553953 DOI: 10.2147/cmar.s194033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 03/07/2019] [Indexed: 01/08/2023] Open
Abstract
Background: Aberrant expression of caveolin-1 (CAV-1) is involved in the pathogenesis of hepatocellular carcinoma (HCC); however, the results have been inconsistent due to the small size of sample in the individual study. Methods: We performed a meta-analysis and evaluated the association of CAV-1 protein overexpression and clinicopathological significance by using Review Manager 5.2. Pooled ORs and HR with corresponding CIs were calculated. Results: Nine studies were included in the meta-analysis with 810 HCC and 172 cirrhosis patients. CAV-1 protein overexpression was correlated with the risk of cirrhosis; OR was 3.25, p=0.01. Furthermore, the rate of CAV-1 protein overexpression was significantly higher in HCC with cirrhosis than HCC without cirrhosis, suggesting that the CAV-1 protein overexpression likely initiated carcinogenesis in liver with cirrhosis and subsequently contributed to the progression of HCC. In addition, CAV-1 protein overexpression was strongly associated with poor differentiated HCC and invasion; ORs were 2.61 and 2.71, respectively. CAV-1 protein overexpression was strongly correlated with poor overall survival in patients with HCC; HR was 0.4, p=0.03. Conclusions: In summary, CAV-1 protein overexpression is at risk for liver cirrhosis and HCC derived from cirrhosis, and CAV-1 is also a promising prognostic predictor in HCC.
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Affiliation(s)
- Yan Zhang
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng 475000, People's Republic of China
| | - Wenjuan Fan
- Medical Bioengineering Key Laboratory, Luohe Medical College, Luohe 462002, People's Republic of China
| | - Jiang Wu
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng 475000, People's Republic of China
| | - Jinglong Dong
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng 475000, People's Republic of China
| | - Zhanjun Cui
- School of Basic Medical Sciences, Henan University, Kaifeng 475004, People's Republic of China
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5
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Lee JJA, Maruyama R, Duddy W, Sakurai H, Yokota T. Identification of Novel Antisense-Mediated Exon Skipping Targets in DYSF for Therapeutic Treatment of Dysferlinopathy. MOLECULAR THERAPY. NUCLEIC ACIDS 2018; 13:596-604. [PMID: 30439648 PMCID: PMC6234522 DOI: 10.1016/j.omtn.2018.10.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/05/2018] [Accepted: 10/05/2018] [Indexed: 12/20/2022]
Abstract
Dysferlinopathy is a progressive myopathy caused by mutations in the dysferlin (DYSF) gene. Dysferlin protein plays a major role in plasma-membrane resealing. Some patients with DYSF deletion mutations exhibit mild symptoms, suggesting some regions of DYSF can be removed without significantly impacting protein function. Antisense-mediated exon-skipping therapy uses synthetic molecules called antisense oligonucleotides to modulate splicing, allowing exons harboring or near genetic mutations to be removed and the open reading frame corrected. Previous studies have focused on DYSF exon 32 skipping as a potential therapeutic approach, based on the association of a mild phenotype with the in-frame deletion of exon 32. To date, no other DYSF exon-skipping targets have been identified, and the relationship between DYSF exon deletion pattern and protein function remains largely uncharacterized. In this study, we utilized a membrane-wounding assay to evaluate the ability of plasmid constructs carrying mutant DYSF, as well as antisense oligonucleotides, to rescue membrane resealing in patient cells. We report that multi-exon skipping of DYSF exons 26–27 and 28–29 rescues plasma-membrane resealing. Successful translation of these findings into the development of clinical antisense drugs would establish new therapeutic approaches that would be applicable to ∼5%–7% (exons 26–27 skipping) and ∼8% (exons 28–29 skipping) of dysferlinopathy patients worldwide.
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Affiliation(s)
- Joshua J A Lee
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
| | - Rika Maruyama
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
| | - William Duddy
- Northern Ireland Centre for Stratified Medicine, Altnagelvin Hospital Campus, Ulster University, Londonderry, United Kingdom
| | - Hidetoshi Sakurai
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Toshifumi Yokota
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada; The Friends of Garrett Cumming Research & Muscular Dystrophy Canada HM Toupin Neurological Science Research Chair, Edmonton, AB T6G 2H7, Canada.
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6
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Shang L, Chen T, Deng Y, Huang Y, Huang Y, Xian J, Lu W, Yang L, Huang Q. Caveolin-3 promotes glycometabolism, growth and proliferation in muscle cells. PLoS One 2017; 12:e0189004. [PMID: 29206848 PMCID: PMC5716543 DOI: 10.1371/journal.pone.0189004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/16/2017] [Indexed: 11/18/2022] Open
Abstract
Objective Caveolin-3 (CAV3) protein is known to be expressed specifically in various myocytes, but its physiological function remains unclear. CAV3, located at the cell membrane, may promote the sensitivity of the Akt signaling pathway, which is closely related to glucose metabolism and to cell growth and proliferation. Methods The CAV3 gene was stably transfected into C2C12 muscle cells, and the effects were evaluated by biochemical assays, WB and confocal microscopy for the observation of cellular glucose metabolism, growth and proliferation, and the effect of CAV3 on the Akt signaling pathway with no insulin stimulation. Results After C2C12 cells were transfected with the mouse CAV3 gene, which increased CAV3 expression, the abundance of the CAV3 and GLUT4 proteins on the cell membrane increased, but the total GLUT4 protein content of the cell was unchanged. Glucose uptake was increased, and this did not affect the glycogen synthesis, but the cell surface area and cell proliferation increased. While there were significant increases in p-Akt and p-p70s6K, which is a downstream component of Akt signaling, the level of GSK3β protein, another component of Akt signaling did not change. Conclusions The muscle, CAV3 protein can activate Akt signaling, increase GLUT4 protein localization in the cell membrane, increase glucose uptake, and promote myocyte growth and proliferation. CAV3 protein has a physiological role in glycometabolism, growth and proliferation, independent of insulin stimulation.
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Affiliation(s)
- Lina Shang
- Department of Physiology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, Guangxi, China
| | - Tingting Chen
- Department of Physiology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, Guangxi, China
| | - Yufeng Deng
- Department of Physiology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, Guangxi, China
| | - Yiyuan Huang
- Department of Physiology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, Guangxi, China
| | - Yuanheng Huang
- Department of Physiology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, Guangxi, China
| | - Jing Xian
- Department of Endocrinology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
| | - Wensheng Lu
- Department of Endocrinology, The People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
| | - Lihui Yang
- Department of Physiology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, Guangxi, China
| | - Qin Huang
- Department of Physiology, School of Basic Medical Sciences, Guangxi Medical University, Nanning, Guangxi, China
- * E-mail:
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Sanon VP, Sawaki D, Mjaatvedt CH, Jourdan‐Le Saux C. Myocardial Tissue Caveolae. Compr Physiol 2015; 5:871-86. [DOI: 10.1002/cphy.c140050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Khodabukus A, Baar K. Glucose Concentration and Streptomycin Alter In Vitro Muscle Function and Metabolism. J Cell Physiol 2015; 230:1226-34. [DOI: 10.1002/jcp.24857] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 10/24/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Alastair Khodabukus
- Division of Neurobiology; Physiology and Behavior; University of California Davis; Davis California
| | - Keith Baar
- Division of Neurobiology; Physiology and Behavior; University of California Davis; Davis California
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9
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Wang J, Qin L, Feng Y, Zheng R, Deng C, Xiong Y, Zuo B. Molecular Characterization, Expression Profile, and Association Study with Meat Quality Traits of Porcine PFKM Gene. Appl Biochem Biotechnol 2014; 173:1640-51. [DOI: 10.1007/s12010-014-0952-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 04/30/2014] [Indexed: 11/24/2022]
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10
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Abstract
Caveolins serve as a platform in plasma membrane associated caveolae to orchestrate various signaling molecules to effectively communicate extracellular signals into the interior of cell. All three types of caveolin, Cav-1, Cav-2 and Cav-3 are expressed throughout the cardiovascular system especially by the major cell types involved including endothelial cells, cardiac myocytes, smooth muscle cells and fibroblasts. The functional significance of caveolins in the cardiovascular system is evidenced by the fact that caveolin loss leads to the development of severe cardiac pathology. Caveolin gene mutations are associated with altered expression of caveolin protein and inherited arrhythmias. Altered levels of caveolins and related downstream signaling molecules in cardiomyopathies validate the integral participation of caveolin in normal cardiac physiology. This chapter will provide an overview of the role caveolins play in cardiovascular disease. Furthering our understanding of the role for caveolins in cardiovascular pathophysiology has the potential to lead to the manipulation of caveolins as novel therapeutic targets.
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11
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Sheriff DS, Ali EF. Perspective on plasma membrane cholesterol efflux and spermatozoal function. J Hum Reprod Sci 2011; 3:68-75. [PMID: 21209749 PMCID: PMC2970794 DOI: 10.4103/0974-1208.69337] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 07/29/2010] [Accepted: 08/05/2010] [Indexed: 01/05/2023] Open
Abstract
The process of sperm maturation, capacitation, and fertilization occur in different molecular milieu provided by epididymis and female reproductive tract including oviduct. The different tissue environment with different oxygen tension and temperature may still influence the process of sperm maturation and capacitation. Reactive oxygen species (ROS) is reported to be an initial switch that may activate the molecular process of capacitation. Therefore, the generation of reactive oxygen species and its possible physiological role depends upon a balance between its formation and degradation in an open environment provided by female reproductive tract. The sensitivity of the spermatozoa to the action of ROS may be due to its exposure for the first time to an oxygen rich external milieu compared to its internal milieu in the male reproductive tract. Reduced temperature in testicular environment coupled with reduced oxygen tension may be the right molecular environment for the process of spermatogenesis and spermiogenesis. The morphologically mature spermatozoa then may attain its motility in an environment provided by the caput epididymis wherein, the dyenin motor can become active. This ability to move forward will make the spermatozoa physiologically fit to undertake its sojourn in the competitive race of fertilization in a new oxygen rich female reproductive tract. The first encounter may be oxygen trigger or preconditioning of the spermatozoa with reactive oxygen species that may alter the spermatozoal function. Infertility is still one of the major global health problems that need medical attention. Apart from the development of artificial methods of reproduction and development of newer techniques in the field of andrology focuses attention on spermatozoal structure and metabolism. Therefore, understanding the molecular mechanisms involved in fertilization in general and that of sperm capacitation in particular may help lead to new and better techniques for enhancing fertility, identifying and treating certain forms of male infertility, and preventing conception. One remarkable insight is the importance of membrane cholesterol efflux in initiating transmembrane signaling events that confer fertilization competence. The identity of the physiologically relevant cholesterol acceptors and modulators of cholesterol efflux is therefore of great interest. Still, it is clear that cholesterol efflux represents only a part of this story. The involvement of phospholipid translocation in mediating dynamic changes in the membrane, rendering it conducive to transmembrane signaling, and the modulation of membrane components of signal transduction cascades by cholesterol or phospholipids will yield important insights into the links between environmental sensing and transmembrane signaling in the sperm. Understanding the membrane molecular events will ultimately provide new and exciting areas of investigation for the future
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12
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Jenkins CM, Yang J, Sims HF, Gross RW. Reversible high affinity inhibition of phosphofructokinase-1 by acyl-CoA: a mechanism integrating glycolytic flux with lipid metabolism. J Biol Chem 2011; 286:11937-50. [PMID: 21258134 DOI: 10.1074/jbc.m110.203661] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The enzyme phosphofructokinase-1 (PFK-1) catalyzes the first committed step of glycolysis and is regulated by a complex array of allosteric effectors that integrate glycolytic flux with cellular bioenergetics. Here, we demonstrate the direct, potent, and reversible inhibition of purified rabbit muscle PFK-1 by low micromolar concentrations of long chain fatty acyl-CoAs (apparent Ki∼1 μM). In sharp contrast, short chain acyl-CoAs, palmitoylcarnitine, and palmitic acid in the presence of CoASH were without effect. Remarkably, MgAMP and MgADP but not MgATP protected PFK-1 against inhibition by palmitoyl-CoA indicating that acyl-CoAs regulate PFK-1 activity in concert with cellular high energy phosphate status. Furthermore, incubation of PFK-1 with [1-(14)C]palmitoyl-CoA resulted in robust acylation of the enzyme that was reversible by incubation with acyl-protein thioesterase-1 (APT1). Importantly, APT1 reversed palmitoyl-CoA-mediated inhibition of PFK-1 activity. Mass spectrometric analyses of palmitoylated PFK-1 revealed four sites of acylation, including Cys-114, Cys-170, Cys-351, and Cys-577. PFK-1 in both skeletal muscle extracts and in purified form was inhibited by S-hexadecyl-CoA, a nonhydrolyzable palmitoyl-CoA analog, demonstrating that covalent acylation of PFK-1 was not required for inhibition. Tryptic footprinting suggested that S-hexadecyl-CoA induced a conformational change in PFK-1. Both palmitoyl-CoA and S-hexadecyl-CoA increased the association of PFK-1 with Ca2+/calmodulin, which attenuated the binding of palmitoylated PFK-1 to membrane vesicles. Collectively, these results demonstrate that fatty acyl-CoA modulates phosphofructokinase activity through both covalent and noncovalent interactions to regulate glycolytic flux and enzyme membrane localization via the branch point metabolic node that mediates lipid flux through anabolic and catabolic pathways.
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Affiliation(s)
- Christopher M Jenkins
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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Couchoux H, Bichraoui H, Chouabe C, Altafaj X, Bonvallet R, Allard B, Ronjat M, Berthier C. Caveolin-3 is a direct molecular partner of the Cav1.1 subunit of the skeletal muscle L-type calcium channel. Int J Biochem Cell Biol 2011; 43:713-20. [PMID: 21262376 DOI: 10.1016/j.biocel.2011.01.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 12/18/2010] [Accepted: 01/17/2011] [Indexed: 12/14/2022]
Abstract
Caveolin-3 is the striated muscle specific isoform of the scaffolding protein family of caveolins and has been shown to interact with a variety of proteins, including ion channels. Mutations in the human CAV3 gene have been associated with several muscle disorders called caveolinopathies and among these, the P104L mutation (Cav-3(P104L)) leads to limb girdle muscular dystrophy of type 1C characterized by the loss of sarcolemmal caveolin. There is still no clear-cut explanation as to specifically how caveolin-3 mutations lead to skeletal muscle wasting. Previous results argued in favor of a role for caveolin-3 in dihydropyridine receptor (DHPR) functional regulation and/or T-tubular membrane localization. It appeared worth closely examining such a functional link and investigating if it could result from the direct physical interaction of the two proteins. Transient expression of Cav-3(P104L) or caveolin-3 specific siRNAs in C2C12 myotubes both led to a significant decrease of the L-type Ca(2+) channel maximal conductance. Immunolabeling analysis of adult skeletal muscle fibers revealed the colocalization of a pool of caveolin-3 with the DHPR within the T-tubular membrane. Caveolin-3 was also shown to be present in DHPR-containing triadic membrane preparations from which both proteins co-immunoprecipitated. Using GST-fusion proteins, the I-II loop of Ca(v)1.1 was identified as the domain interacting with caveolin-3, with an apparent affinity of 60nM. The present study thus revealed a direct molecular interaction between caveolin-3 and the DHPR which is likely to underlie their functional link and whose loss might therefore be involved in pathophysiological mechanisms associated to muscle caveolinopathies.
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Affiliation(s)
- Harold Couchoux
- Physiologie Intégrative Cellulaire et Moléculaire, Université Lyon 1, UMR CNRS 5123, Université de Lyon, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne, France
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14
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Kruszynska YT, Ciaraldi TP, Henry RR. Regulation of Glucose Metabolism in Skeletal Muscle. Compr Physiol 2011. [DOI: 10.1002/cphy.cp070218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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15
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Catteruccia M, Sanna T, Santorelli FM, Tessa A, Di Giacopo R, Sauchelli D, Verbo A, Lo Monaco M, Servidei S. Rippling muscle disease and cardiomyopathy associated with a mutation in the CAV3 gene. Neuromuscul Disord 2009; 19:779-83. [PMID: 19773168 DOI: 10.1016/j.nmd.2009.08.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 08/08/2009] [Accepted: 08/27/2009] [Indexed: 10/20/2022]
Abstract
Caveolin-3, the myocyte-specific isoform of caveolins, is preferentially expressed in skeletal, cardiac and smooth muscles. Mutations in the CAV3 gene cause clinically heterogeneous neuromuscular disorders, including rippling muscle disease, or cardiopathies. The same mutation may lead to different phenotypes, but cardiac and muscle involvement rarely coexists suggesting that the molecular network acting with caveolin-3 in skeletal muscle and heart may differ. Here we describe an Italian family (a father and his two sons) with clinical and neurophysiological features of rippling muscle disease and heart involvement characterized by atrio-ventricular conduction defects and dilated cardiomyopathy. Muscle biopsy showed loss of caveolin-3 immunosignal. Molecular studies identified the p.A46V mutation in CAV3 previously reported in a German family with autosomal dominant rippling muscle disease and sudden death in few individuals. We suggest that cardiac dysfunction in myopathic patients with CAV3 mutations may be underestimated and recommend a more thorough evaluation for the presence of cardiomyopathy and potentially lethal arrhythmias.
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Affiliation(s)
- Michela Catteruccia
- Department of Neuroscience, Institute of Neurology, Catholic University, Largo Agostino Gemelli 8, 00168 Rome, Italy
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Abstract
In muscle tissue the protein caveolin-3 forms caveolae--flask-shaped invaginations localized on the cytoplasmic surface of the sarcolemmal membrane. Caveolae have a key role in the maintenance of plasma membrane integrity and in the processes of vesicular trafficking and signal transduction. Mutations in the caveolin-3 gene lead to skeletal muscle pathology through multiple pathogenetic mechanisms. Indeed, caveolin-3 deficiency is associated to sarcolemmal membrane alterations, disorganization of skeletal muscle T-tubule network and disruption of distinct cell-signaling pathways. To date, there have been 30 caveolin-3 mutations identified in the human population. Caveolin-3 defects lead to four distinct skeletal muscle disease phenotypes: limb girdle muscular dystrophy, rippling muscle disease, distal myopathy, and hyperCKemia. In addition, one caveolin-3 mutant has been described in a case of hypertrophic cardiomyopathy. Many patients show an overlap of these symptoms and the same mutation can be linked to different clinical phenotypes. This variability can be related to additional genetic or environmental factors. This review will address caveolin-3 biological functions in muscle cells and will describe the muscle and heart disease phenotypes associated with caveolin-3 mutations.
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17
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Lee HJ, Park CH, Lee SJ, Park JW, Choi JH, Ryu GH, Kwon BS. Expression of caveolin-3 immunoreactivities in the developing sciatic nerve of the rat. Muscle Nerve 2008; 38:1021-6. [PMID: 18720574 DOI: 10.1002/mus.20973] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Caveolae are formed by the caveolin (CAV) family of proteins, CAV-1, -2, and -3. CAV-1 and -2 are co expressed in many cell types, whereas CAV-3 is muscle-specific and mutation of the CAV-3 gene causes muscular dystrophy. CAV-3 has also been detected in brain astroglial cells and in peripheral nerves along with CAV-1. Therefore, we sought to determine whether CAV-3 protein is expressed in developing peripheral nerves by using immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). We found that CAV-3 immunoreactivities (IRs) were Localized in the myelin sheath during peripheral nerve development. CAV-3 IRs were intense during the early postnatal stage, but decreased as the peripheral nerves matured at postnatal weeks 3-5. CAV-3 mRNA expression was also markedly decreased during postnatal development. Because the expression pattern of CAV-3 IRs was opposite that of CAV-1 IRs. CAV-1 and -3 might be involved in different phases of peripheral nerve myelination and play complementary roles in myelin maturation and peripheral nerve development.
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Affiliation(s)
- Ho J Lee
- Department of Rehabilitation Medicine, Dongguk University College of Medicine, Gyeongju, Korea
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Aboumousa A, Hoogendijk J, Charlton R, Barresi R, Herrmann R, Voit T, Hudson J, Roberts M, Hilton-Jones D, Eagle M, Bushby K, Straub V. Caveolinopathy--new mutations and additional symptoms. Neuromuscul Disord 2008; 18:572-8. [PMID: 18583131 DOI: 10.1016/j.nmd.2008.05.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 05/01/2008] [Accepted: 05/06/2008] [Indexed: 11/30/2022]
Abstract
Mutations in the caveolin-3 gene (CAV3) can lead to a broad spectrum of clinical phenotypes. Phenotypes that have so far been associated with primary caveolin-3 deficiency include limb girdle muscular dystrophy, rippling muscle disease, distal myopathy and hyperCKaemia. This is the first report describing the clinical, pathological and genetic features of patients with caveolinopathy from the UK. Ten patients (six families) were identified via the National Commissioning Group (NCG) service for patients with limb girdle muscle dystrophy in Newcastle. Myalgia was the most prominent symptom in our cohort of patients and for 50% it was the reason for referral. Muscle weakness was only found in 60% of the patients, whereas rippling muscle movement was present in 80%. One of the patients reported episodes of myoglobinuria and another one episodes of hypoglycaemia. Five different mutations were identified, two of which were novel and three that had previously been described. Caveolinopathy needs to be considered as a differential diagnosis in a range of clinical situations, including in patients who do not have any weakness. Indeed, rippling muscles are a more frequent symptom than weakness, and can be detected in childhood. Presentation with myalgia is common and management of it as well as of myoglobinuria and hypoglycaemia may have a major impact on the patients' quality of life.
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Affiliation(s)
- Ahmed Aboumousa
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK
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19
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Weiss N, Couchoux H, Legrand C, Berthier C, Allard B, Jacquemond V. Expression of the muscular dystrophy-associated caveolin-3(P104L) mutant in adult mouse skeletal muscle specifically alters the Ca(2+) channel function of the dihydropyridine receptor. Pflugers Arch 2008; 457:361-75. [PMID: 18509671 DOI: 10.1007/s00424-008-0528-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Revised: 04/30/2008] [Accepted: 05/07/2008] [Indexed: 12/11/2022]
Abstract
Caveolins are plasma-membrane-associated proteins potentially involved in a variety of signalling pathways. Different mutations in CAV3, the gene encoding for the muscle-specific isoform caveolin-3 (Cav-3), lead to muscle diseases, but the underlying molecular mechanisms remain largely unknown. Here, we explored the functional consequences of a Cav-3 mutation (P104L) inducing the 1C type limb-girdle muscular dystrophy (LGMD 1C) in human on intracellular Ca(2+) regulation of adult skeletal muscle fibres. A YFP-tagged human Cav-3(P104L) mutant was expressed in vivo in muscle fibres from mouse. Western blot analysis revealed that expression of this mutant led to an approximately 80% drop of the level of endogenous Cav-3. The L-type Ca(2+) current density was found largely reduced in fibres expressing the Cav-3(P104L) mutant, with no change in the voltage dependence of activation and inactivation. Interestingly, the maximal density of intramembrane charge movement was unaltered in the Cav-3(P104L)-expressing fibres, suggesting no change in the total amount of functional voltage-sensing dihydropyridine receptors (DHPRs). Also, there was no obvious alteration in the properties of voltage-activated Ca(2+) transients in the Cav-3(P104L)-expressing fibres. Although the actual role of the Ca(2+) channel function of the DHPR is not clearly established in adult skeletal muscle, its specific alteration by the Cav-3(P104L) mutant suggests that it may be involved in the physiopathology of LGMD 1C.
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Affiliation(s)
- Norbert Weiss
- Physiologie Intégrative Cellulaire et Moléculaire, Université Claude Bernard-Lyon 1,Villeurbanne Cedex, France
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20
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Fanzani A, Musarò A, Stoppani E, Giuliani R, Colombo F, Preti A, Marchesini S. Hypertrophy and atrophy inversely regulate Caveolin-3 expression in myoblasts. Biochem Biophys Res Commun 2007; 357:314-8. [PMID: 17418092 DOI: 10.1016/j.bbrc.2007.03.148] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Accepted: 03/24/2007] [Indexed: 11/23/2022]
Abstract
Caveolin-3 (Cav-3) is a muscle-specific membrane protein crucial for myoblast differentiation, as loss of the protein due to mutations within the gene causes an autosomal dominant form of limb girdle muscular dystrophy 1-c. Here we show that along with p38 activity the PI3-kinase/AKT/mTOR pathway is required for proper Cav-3 up-regulation during muscle differentiation and hypertrophy, as confirmed by the marked increase of Cav-3 expression in hypertrophied C2C12 cells transfected with an activated form of AKT. Accordingly, Cav-3 expression was further increased during hypertrophy of L6C5 myoblasts treated with Arg(8)-vasopressin and in hypertrophic muscles of MLC/mIGF-1 transgenic mice. In contrast, Cav-3 expression was down-regulated in C2C12 myotubes exposed to atrophic stimuli such as starvation or treatment with dexamethasone. This study clearly suggests that Cav-3 expression is causally linked to the maturation of muscle phenotype and it is tightly regulated by hypertrophic and atrophic stimuli.
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Affiliation(s)
- Alessandro Fanzani
- Department of Biomedical Sciences and Biotechnology, Unit of Biochemistry, University of Brescia, Italy.
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21
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Couchoux H, Allard B, Legrand C, Jacquemond V, Berthier C. Loss of caveolin-3 induced by the dystrophy-associated P104L mutation impairs L-type calcium channel function in mouse skeletal muscle cells. J Physiol 2007; 580:745-54. [PMID: 17317753 PMCID: PMC2075458 DOI: 10.1113/jphysiol.2006.124198] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Caveolins are membrane scaffolding proteins that associate with and regulate a variety of signalling proteins, including ion channels. A deficiency in caveolin-3 (Cav-3), the major striated muscle isoform, is responsible for skeletal muscle disorders, such as limb-girdle muscular dystrophy 1C (LGMD 1C). The molecular mechanisms leading to the muscle wasting that characterizes this pathology are poorly understood. Here we show that a loss of Cav-3 induced by the expression of the LGMD 1C-associated mutant P104L (Cav-3(P104L)) provokes a reduction by half of the maximal conductance of the voltage-dependent L-type Ca(2+) channel in mouse primary cultured myotubes and fetal skeletal muscle fibres. Confocal immunomiscrocopy indicated a colocalization of Cav-3 and Ca(v)1.1, the pore-forming subunit of the L-type Ca(2+) channel, at the surface membrane and in the developing T-tubule network in control myotubes and fetal fibres. In myotubes expressing Cav-3(P104L), the loss of Cav-3 was accompanied by a 66% reduction in Ca(v)1.1 mean labelling intensity. Our results suggest that Cav-3 is involved in L-type Ca(2+) channel membrane function and localization in skeletal muscle cells and that an alteration of L-type Ca(2+) channels could be involved in the physiopathological mechanisms of caveolinopathies.
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Affiliation(s)
- Harold Couchoux
- University Lyon 1, CNRS, Laboratory of Integrative, Cellular and Molecular Physiology, Villeurbanne, F-69622, France
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22
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Davies KE, Nowak KJ. Molecular mechanisms of muscular dystrophies: old and new players. Nat Rev Mol Cell Biol 2006; 7:762-73. [PMID: 16971897 DOI: 10.1038/nrm2024] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The study of the muscle cell in the muscular dystrophies (MDs) has shown that mutant proteins result in perturbations of many cellular components. MDs have been associated with mutations in structural proteins, signalling molecules and enzymes as well as mutations that result in aberrant processing of mRNA or alterations in post-translational modifications of proteins. These findings have not only revealed important insights for cell biologists, but have also provided unexpected and exciting new approaches for therapy.
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Affiliation(s)
- Kay E Davies
- Department of Physiology, Anatomy and Genetics, MRC Functional Genetics Unit, South Parks Road, Oxford OX1 3QX, UK.
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23
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Raikar LS, Vallejo J, Lloyd PG, Hardin CD. Overexpression of caveolin-1 results in increased plasma membrane targeting of glycolytic enzymes: The structural basis for a membrane associated metabolic compartment. J Cell Biochem 2006; 98:861-71. [PMID: 16453288 DOI: 10.1002/jcb.20732] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Although membrane-associated glycolysis has been observed in a variety of cell types, the mechanism of localization of glycolytic enzymes to the plasma membrane is not known. We hypothesized that caveolin-1 (CAV-1) serves as a scaffolding protein for glycolytic enzymes and may play a role in the organization of cell metabolism. To test this hypothesis, we over-expressed CAV-1 in cultured A7r5 (rat aorta vascular smooth muscle; VSM) cells. Confocal immunofluorescence microscopy was used to study the distribution of phosphofructokinase (PFK) and CAV-1 in the transfected cells. Areas of interest (AOI) were analyzed in a central Z-plane across the cell transversing the perinuclear region. To quantify any shift in PFK localization resulting from CAV-1 over-expression, we calculated a periphery to center (PC) index by taking the average of the two outer AOIs from each membrane region and dividing by the central one or two AOIs. We found the PC index to be 1.92 +/- 0.57 (mean +/- SEM, N = 8) for transfected cells and 0.59 +/- 0.05 (mean +/- SEM, N = 11) for control cells. Colocalization analysis demonstrated that the percentage of PFK associated with CAV-1 increased in transfected cells compared to control cells. The localization of aldolase (ALD) was also shifted towards the plasma membrane (and colocalized with PFK) in CAV-1 over-expressing cells. These results demonstrate that CAV-1 creates binding sites for PFK and ALD that may be of higher affinity than those binding sites localized in the cytoplasm. We conclude that CAV-1 functions as a scaffolding protein for PFK, ALD and perhaps other glycolytic enzymes, either through direct interaction or accessory proteins, thus contributing to compartmented metabolism in vascular smooth muscle.
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Affiliation(s)
- Leena S Raikar
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri 65212, USA
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24
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Abraham SN, Duncan MJ, Li G, Zaas D. Bacterial penetration of the mucosal barrier by targeting lipid rafts. J Investig Med 2005; 53:318-21. [PMID: 16207470 DOI: 10.2310/6650.2005.53609] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Several traditionally extracellular pathogens not known to possess invasive capacity have been shown to invade various mucosal epithelial cells. The mucosal epithelium performs an important barrier function and is not typically amenable to bacterial invasion. Valuable clues to the underlying basis for bacterial invasion have emerged from recent studies examining the invasion of bladder epithelial cells by uropathogenic Escherichia coli and alveolar epithelial cells by Pseudomonas aeruginosa. In both cases, bacterial invasion is achieved through targeting of molecules specifically found within distinct glycosphingolipid- and cholesterol-enriched microdomains called lipid rafts. The importance of lipid rafts in promoting bacterial invasion was shown as disruptors of lipid rafts blocked cellular invasion by both E. coli and P. aeruginosa. In addition, molecular components of lipid rafts were found to be highly enriched in membranes encasing these intracellular bacteria. Furthermore, caveolin proteins, which serve to stabilize and organize lipid raft components, are necessary for bacterial entry. Taken together, targeting of lipid rafts appears to be an effective but poorly recognized mechanism used by pathogenic bacteria to circumvent the mucosal barriers of the host.
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Affiliation(s)
- Soman N Abraham
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA.
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25
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Nixon SJ, Wegner J, Ferguson C, Méry PF, Hancock JF, Currie PD, Key B, Westerfield M, Parton RG. Zebrafish as a model for caveolin-associated muscle disease; caveolin-3 is required for myofibril organization and muscle cell patterning. Hum Mol Genet 2005; 14:1727-43. [PMID: 15888488 DOI: 10.1093/hmg/ddi179] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Caveolae are an abundant feature of many animal cells. However, the exact function of caveolae remains unclear. We have used the zebrafish, Danio rerio, as a system to understand caveolae function focusing on the muscle-specific caveolar protein, caveolin-3 (Cav3). We have identified caveolin-1 (alpha and beta), caveolin-2 and Cav3 in the zebrafish. Zebrafish Cav3 has 72% identity to human CAV3, and the amino acids altered in human muscle diseases are conserved in the zebrafish protein. During embryonic development, cav3 expression is apparent by early segmentation stages in the first differentiating muscle precursors, the adaxial cells and slightly later in the notochord. cav3 expression appears in the somites during mid-segmentation stages and then later in the pectoral fins and facial muscles. Cav3 and caveolae are located along the entire sarcolemma of late stage embryonic muscle fibers, whereas beta-dystroglycan is restricted to the muscle fiber ends. Down-regulation of Cav3 expression causes gross muscle abnormalities and uncoordinated movement. Ultrastructural analysis of isolated muscle fibers reveals defects in myoblast fusion and disorganized myofibril and membrane systems. Expression of the zebrafish equivalent to a human muscular dystrophy mutant, CAV3P104L, causes severe disruption of muscle differentiation. In addition, knockdown of Cav3 resulted in a dramatic up-regulation of eng1a expression resulting in an increase in the number of muscle pioneer-like cells adjacent to the notochord. These studies provide new insights into the role of Cav3 in muscle development and demonstrate its requirement for correct intracellular organization and myoblast fusion.
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Affiliation(s)
- Susan J Nixon
- Institute for Molecular Bioscience, Universitky of Queensland, Brisbane 4072, Australia
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26
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Iyengar P, Espina V, Williams TW, Lin Y, Berry D, Jelicks LA, Lee H, Temple K, Graves R, Pollard J, Chopra N, Russell RG, Sasisekharan R, Trock BJ, Lippman M, Calvert VS, Petricoin EF, Liotta L, Dadachova E, Pestell RG, Lisanti MP, Bonaldo P, Scherer PE. Adipocyte-derived collagen VI affects early mammary tumor progression in vivo, demonstrating a critical interaction in the tumor/stroma microenvironment. J Clin Invest 2005; 115:1163-76. [PMID: 15841211 PMCID: PMC1077173 DOI: 10.1172/jci23424] [Citation(s) in RCA: 293] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2004] [Accepted: 03/01/2005] [Indexed: 12/24/2022] Open
Abstract
The interactions of transformed cells with the surrounding stromal cells are of importance for tumor progression and metastasis. The relevance of adipocyte-derived factors to breast cancer cell survival and growth is well established. However, it remains unknown which specific adipocyte-derived factors are most critical in this process. Collagen VI is abundantly expressed in adipocytes. Collagen(-/-) mice in the background of the mouse mammary tumor virus/polyoma virus middle T oncogene (MMTV-PyMT) mammary cancer model demonstrate dramatically reduced rates of early hyperplasia and primary tumor growth. Collagen VI promotes its growth-stimulatory and pro-survival effects in part by signaling through the NG2/chondroitin sulfate proteoglycan receptor expressed on the surface of malignant ductal epithelial cells to sequentially activate Akt and beta-catenin and stabilize cyclin D1. Levels of the carboxyterminal domain of collagen VIalpha3, a proteolytic product of the full-length molecule, are dramatically upregulated in murine and human breast cancer lesions. The same fragment exerts potent growth-stimulatory effects on MCF-7 cells in vitro. Therefore, adipocytes play a vital role in defining the ECM environment for normal and tumor-derived ductal epithelial cells and contribute significantly to tumor growth at early stages through secretion and processing of collagen VI.
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Affiliation(s)
- Puneeth Iyengar
- Department of Cell Biology, Albert Einstein Cancer Center, Albert Einstein College of Medicine, New York, New York 10461, USA
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27
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Sotgia F, Bonuccelli G, Minetti C, Woodman SE, Capozza F, Kemp RG, Scherer PE, Lisanti MP. Phosphofructokinase muscle-specific isoform requires caveolin-3 expression for plasma membrane recruitment and caveolar targeting: implications for the pathogenesis of caveolin-related muscle diseases. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 163:2619-34. [PMID: 14633633 PMCID: PMC1892361 DOI: 10.1016/s0002-9440(10)63616-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous co-immunoprecipitation studies have shown that endogenous PFK-M (phosphofructokinase, muscle-specific isoform) associates with caveolin (Cav)-3 under certain metabolic conditions. However, it remains unknown whether Cav-3 expression is required for the plasma membrane recruitment and caveolar targeting of PFK-M. Here, we demonstrate that recombinant expression of Cav-3 dramatically affects the subcellular localization of PFK-M, by targeting PFK-M to the plasma membrane, and by trans-locating PFK-M to caveolae-enriched membrane domains. In addition, we show that the membrane recruitment and caveolar targeting of PFK-M appears to be strictly dependent on the concentration of extracellular glucose. Interestingly, recombinant expression of PFK-M with three Cav-3 mutants [DeltaTFT (63 to 65), P104L, and R26Q], which harbor the same mutations as seen in the human patients with Cav-3-related muscle diseases, causes a substantial reduction in PFK-M expression levels, and impedes the membrane recruitment of PFK-M. Analysis of skeletal muscle tissue samples from Cav-3(-/-) mice directly demonstrates that Cav-3 expression regulates the phenotypic behavior of PFK-M. More specifically, in Cav-3-null mice, PFK-M is no longer targeted to the plasma membrane, and is excluded from caveolar membrane domains. As such, our current results may be important in understanding the pathogenesis of Cav-3-related muscle diseases, such as limb-girdle muscular dystrophy-1C, distal myopathy, and rippling muscle disease, that are caused by mutations within the human Cav-3 gene.
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Affiliation(s)
- Federica Sotgia
- Departments of Molecular Pharmacology and Cell Biology, and The Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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28
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Vallejo J, Hardin CD. Metabolic organization in vascular smooth muscle: distribution and localization of caveolin-1 and phosphofructokinase. Am J Physiol Cell Physiol 2004; 286:C43-54. [PMID: 12944325 DOI: 10.1152/ajpcell.00483.2002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have shown that a compartmentation of glycolysis and gluconeogenesis exists in vascular smooth muscle (VSM) and that an intact plasma membrane is essential for compartmentation. Previously, we observed that disruption of the caveolae inhibited glycolysis but stimulated gluconeogenesis, suggesting a link between caveolae and glycolysis. We hypothesized that glycolytic enzymes specifically localize to caveolae. We used confocal microscopy to determine the localization of caveolin-1 (CAV-1) and phosphofructokinase (PFK) in freshly isolated VSM cells and cultured A7r5 cells. Freshly isolated cells exhibited a peripheral (membrane) localization of CAV-1 with 85.3% overlap with PFK. However, only 59.9% of PFK was localized with CAV-1, indicating a wider distribution of PFK than CAV-1. A7r5 cells exhibited compartmentation of glycolysis and gluconeogenesis and displayed two apparent phenotypes distinguishable by shape (spindle and ovoid shaped). In both phenotypes, CAV-1 fluorescence overlapped with PFK fluorescence (83.1 and 81.5%, respectively). However, the overlap of PFK with CAV-1 was lower in the ovoid-shaped (35.9%) than the spindle-shaped cells (53.7%). There was also a progressive shift in pattern of colocalization from primarily the membrane in spindle-shaped cells (both freshly isolated and cultured cells) to primarily the cytoplasm in ovoid-shaped cells. Overall, cellular colocalization of PFK with CAV-1 was significant in all cell types (0.68 > or = R2 < or = 0.77). Coimmunoprecipitation of PFK with CAV-1 further validated the possible interaction between the proteins. We conclude that a similar distribution of one pool of PFK with CAV-1 contributes to the compartmentation of glycolysis from gluconeogenesis.
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Affiliation(s)
- Johana Vallejo
- Department of Medical Pharmacology and Physiology, MA 415 Medical Sciences Bldg., University of Missouri, Columbia, MO 65212, USA
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29
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Travis AJ, Kopf GS. The role of cholesterol efflux in regulating the fertilization potential of mammalian spermatozoa. J Clin Invest 2002. [DOI: 10.1172/jci0216392] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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30
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Travis AJ, Kopf GS. The role of cholesterol efflux in regulating the fertilization potential of mammalian spermatozoa. J Clin Invest 2002; 110:731-6. [PMID: 12235100 PMCID: PMC151136 DOI: 10.1172/jci16392] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Alexander J Travis
- Center for Research on Reproduction and Women's Health, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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31
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Sola-Penna M, dos Santos AC, Alves GG, El-Bacha T, Faber-Barata J, Pereira MF, Serejo FC, Da Poian AT, Sorenson M. A radioassay for phosphofructokinase-1 activity in cell extracts and purified enzyme. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2002; 50:129-40. [PMID: 11741702 DOI: 10.1016/s0165-022x(01)00180-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phosphofructokinase-1 plays a key role in the regulation of carbohydrate metabolism. Its activity can be used as an indicator of the glycolytic flux in a tissue sample. The method most commonly employed to determine phosphofructokinase-1 activity is based on oxidation of NADH by the use of aldolase, triosephosphate isomerase, and alpha-glycerophosphate dehydrogenase. This method suffers from several disadvantages, including interactions of the auxiliary enzymes with phosphofructokinase-1. Other methods that have been used also require auxiliary enzymes or are less sensitive than a coupled assay. Here, we propose a direct method to determine phosphofructokinase-1 activity, without the use of auxiliary enzymes. This method employs fructose-6-phosphate and ATP labeled with 32P in the gamma position ([gamma-32P]ATP), and leads to the formation of ADP and fructose-1,6-bisphosphate labeled with 32P ([1-32P]fructose-1,6-bisphosphate). Activated charcoal is used to adsorb unreacted [gamma-32P]ATP, and the radioactive product in the supernatant, [1-32P]fructose-1,6-bisphosphate, is analyzed on a liquid scintillation counter. The proposed method is precise and relatively inexpensive, and can be applied to determine phosphofructokinase-1 activity in cellular extracts as well as in the purified enzyme.
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Affiliation(s)
- Mauro Sola-Penna
- Laboratório de Enzimologia e Controle do Metabolismo (LabECoM), Departamento de Fármacos, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, RJ 21944-910, Brazil.
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32
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Travis AJ, Merdiushev T, Vargas LA, Jones BH, Purdon MA, Nipper RW, Galatioto J, Moss SB, Hunnicutt GR, Kopf GS. Expression and localization of caveolin-1, and the presence of membrane rafts, in mouse and Guinea pig spermatozoa. Dev Biol 2001; 240:599-610. [PMID: 11784086 DOI: 10.1006/dbio.2001.0475] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In somatic cells, caveolin-1 plays several roles in membrane dynamics, including organization of detergent-insoluble lipid rafts, trafficking of cholesterol, and anchoring of signaling molecules. Events in sperm capacitation and fertilization require similar cellular functions, suggesting a possible role for caveolin-1 in spermatozoa. Immunoblot analysis demonstrated that caveolin-1 was indeed present in developing mouse male germ cells and both mouse and guinea pig spermatozoa. In mature spermatozoa, caveolin-1 was enriched in a Triton X-100-insoluble membrane fraction, as well as in membrane subdomains separable by means of their light buoyant densities through sucrose density gradient centrifugation. These data indicated the presence of membrane rafts enriched in caveolin-1 in spermatozoa. Indirect immunofluorescence analysis revealed caveolin-1 in the regions of the acrosome and flagellum in sperm of both species. Confocal immunofluorescence analysis of developing mouse male germ cells demonstrated partial co-localization with a marker for the acrosome. Furthermore, syntaxin-2, a protein involved in acrosomal exocytosis, was present in both raft and nonraft fractions in mature sperm. Together, these data indicated that sperm membranes possess distinct raft subdomains, and that caveolin-1 localized to regions appropriate for involvement with acrosomal biogenesis and exocytosis, as well as signaling pathways regulating such processes as capacitation and flagellar motility.
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Affiliation(s)
- A J Travis
- Center for Research on Reproduction and Women's Health, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6142, USA
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33
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Lloyd PG, Hardin CD. Caveolae and the organization of carbohydrate metabolism in vascular smooth muscle. J Cell Biochem 2001; 82:399-408. [PMID: 11500916 DOI: 10.1002/jcb.1170] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We have previously found that glycolysis and gluconeogenesis occur in separate "compartments" of the VSM cell. These compartments may result from spatial separation of glycolytic and gluconeogenic enzymes (Lloyd and Hardin [1999] Am J Physiol Cell Physiol. 277:C1250-C1262). We have also found that an intact plasma membrane is essential for compartmentation to exist (Lloyd and Hardin [2000] Am J Physiol Cell Physiol. 278:C803-C811), suggesting that glycolysis and gluconeogenesis may be associated with distinct plasma membrane microdomains. Caveolae are one such microdomain, in which proteins of related function colocalize. Thus, we hypothesized that membrane-associated glycolysis occurs in association with caveolae, while gluconeogenesis is localized to non-caveolae domains. To test this hypothesis, we disrupted caveolae in vascular smooth muscle (VSM) of pig cerebral microvessels (PCMV) with beta methyl-cyclodextrin (CD) and examined the metabolism of [2-(13)C]glucose (a glycolytic substrate) and [1-(13)C]fructose 1,6-bisphosphate (FBP, a gluconeogenic substrate in PCMV) using (13)C nuclear magnetic resonance spectroscopy. Caveolar disruption reduced flux of [2-(13)C]glucose to [2-(13)C]lactate, suggesting that caveolar disruption partially disrupted the glycolytic pathway. Caveolae disruption may also have resulted in a breakdown of compartmentation, since conversion of [1-(13)C]FBP to [3-(13)C]lactate was increased by CD treatment. Alternatively, the increased [3-(13)C]lactate production may reflect changes in FBP uptake, since conversion of [1-(13)C]FBP to [3-(13)C]glucose was also elevated in CD-treated cells. Thus, a link between caveolar organization and metabolic organization may exist.
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Affiliation(s)
- P G Lloyd
- Department of Physiology, University of Missouri, Columbia, Missouri 65212, USA
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34
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Abstract
Caveolae are vesicular invaginations of the plasma membrane, and function as 'message centers' for regulating signal transduction events. Caveolin-3, a muscle-specific caveolin-related protein, is the principal structural protein of caveolar membrane domains in skeletal muscle and in the heart. Several mutations within the coding sequence of the human caveolin-3 gene (located at 3p25) have been identified. Mutations that lead to a loss of approximately 95% of caveolin-3 protein expression are responsible for a novel autosomal dominant form of limb-girdle muscular dystrophy (LGMD-1C) in humans. By contrast, upregulation of the caveolin-3 protein is associated with Duchenne muscular dystrophy (DMD). Thus, tight regulation of caveolin-3 appears essential for maintaining normal muscle health and homeostasis.
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Affiliation(s)
- F Galbiati
- Department of Pharmacology, University of Pittsburgh School of Medicine, Biomedical Science Tower (BST), Rm E1356, Pittsburgh, PA 15261, USA
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35
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Abstract
Muscular dystrophies represent a heterogeneous group of disorders, which have been largely classified by clinical phenotype. In the last 10 years, identification of novel skeletal muscle genes including extracellular matrix, sarcolemmal, cytoskeletal, cytosolic, and nuclear membrane proteins has changed the phenotype-based classification and shed new light on the molecular pathogenesis of these disorders. A large number of genes involved in muscular dystrophy encode components of the dystrophin-glycoprotein complex (DGC) which normally links the intracellular cytoskeleton to the extracellular matrix. Mutations in components of this complex are thought to lead to loss of sarcolemmal integrity and render muscle fibers more susceptible to damage. Recent evidence suggests the involvement of vascular smooth muscle DGC in skeletal and cardiac muscle pathology in some forms of sarcoglycan-deficient limb-girdle muscular dystrophy. Intriguingly, two other forms of limb-girdle muscular dystrophy are possibly caused by perturbation of sarcolemma repair mechanisms. The complete clarification of these various pathways will lead to further insights into the pathogenesis of this heterogeneous group of muscle disorders.
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Affiliation(s)
- R D Cohn
- Howard Hughes Medical Institute, Department of Physiology and Biophysics and of Neurology, University of Iowa College of Medicine, 400 EMRB, Iowa City, Iowa 52242, USA
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36
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Meacci E, Donati C, Cencetti F, Romiti E, Farnararo M, Bruni P. Receptor-activated phospholipase D is present in caveolin-3-enriched light membranes of C2C12 myotubes. FEBS Lett 2000; 473:10-4. [PMID: 10802049 DOI: 10.1016/s0014-5793(00)01486-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Caveolin-3 (cav-3) is a key structural component of caveolar membrane in skeletal muscle. Cav-3-enriched light membrane (CELM) fractions obtained from C2C12 myotubes contain phospholipase D1 (PLD1) and its major regulators, RhoA and protein kinase Calpha (PKCalpha). All these proteins were found bound to cav-3. An in vivo assay of PLD activity, which allows to localize the reaction product in CELMs, indicated that the enzyme associated to this membrane microdomain was active. Moreover, bradykinin (BK), thrombin and phorbol 12-myristate 13-acetate induced rapid stimulation of PLD activity in CELMs. The cav-3-PLD1 complex was not affected by BK treatment, whereas the agonist induced a marked increase of RhoA association with cav-3. Furthermore, BK-induced PLD activation in CELMs was dependent, at least in part, on PKCalpha.
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Affiliation(s)
- E Meacci
- Dipartimento di Scienze Biochimiche, Università di Firenze, Viale G. B. Morgagni 50, 50134, Firenze, Italy.
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37
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Pilon A, Briand O, Lestavel S, Copin C, Majd Z, Fruchart JC, Castro G, Clavey V. Apolipoprotein AII enrichment of HDL enhances their affinity for class B type I scavenger receptor but inhibits specific cholesteryl ester uptake. Arterioscler Thromb Vasc Biol 2000; 20:1074-81. [PMID: 10764676 DOI: 10.1161/01.atv.20.4.1074] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Apolipoproteins of high density lipoprotein (HDL) and especially apolipoprotein (apo)AI and apoAII have been demonstrated as binding directly to the class B type I scavenger receptor (SR-BI), the HDL receptor that mediates selective cholesteryl ester uptake. However, the functional relevance of the binding capacity of each apolipoprotein is still unknown. The human adrenal cell line, NCI-H295R, spontaneously expresses a high level of SR-BI, the major apoAI binding protein in these cells. As previously described for murine SR-BI, free apoAI, palmitoyl-oleoyl-phosphatidylcholine (POPC)-AI, and HDL are good ligands for human SR-BI. In vitro displacement of apoAI by apoAII in HDLs or in Lp AI purified from HDL by immunoaffinity enhances their ability to compete with POPC-AI to bind to SR-BI and also enhances their direct binding capacity. The next step was to determine whether the higher affinity of apoAII for SR-BI correlated with the specific uptake of cholesteryl esters from these HDLs. Free apoAII and, to a lesser extent, free apoAI that were added to the cell medium during uptake experiments inhibited the specific uptake of [(3)H]cholesteryl esters from HDL, indicating that binding sites on cells were the same as cholesteryl ester uptake sites. In direct experiments, the uptake of [(3)H]cholesteryl esters from apoAII-enriched HDL was highly reduced compared with the uptake from native HDL. These results demonstrate that in the human adrenal cell line expressing SR-BI as the major HDL binding protein, efficient apoAII binding has an inhibitory effect on the delivery of cholesteryl esters to cells.
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Affiliation(s)
- A Pilon
- INSERM U325, Institut Pasteur de Lille et Université Lille 2, Lille, France
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38
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Lloyd PG, Hardin CD. Sorting of metabolic pathway flux by the plasma membrane in cerebrovascular smooth muscle cells. Am J Physiol Cell Physiol 2000; 278:C803-11. [PMID: 10751328 DOI: 10.1152/ajpcell.2000.278.4.c803] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We used beta-escin-permeabilized pig cerebral microvessels (PCMV) to study the organization of carbohydrate metabolism in the cytoplasm of vascular smooth muscle (VSM) cells. We have previously demonstrated (Lloyd PG and Hardin CD. Am J Physiol Cell Physiol 277: C1250-C1262, 1999) that intact PCMV metabolize the glycolytic intermediate [1-(13)C]fructose 1,6-bisphosphate (FBP) to [1-(13)C]glucose with negligible production of [3-(13)C]lactate, while simultaneously metabolizing [2-(13)C]glucose to [2-(13)C]lactate. Thus gluconeogenic and glycolytic intermediates do not mix freely in intact VSM cells (compartmentation). Permeabilized PCMV retained the ability to metabolize [2-(13)C]glucose to [2-(13)C]lactate and to metabolize [1-(13)C]FBP to [1-(13)C]glucose. The continued existence of glycolytic and gluconeogenic activity in permeabilized cells suggests that the intermediates of these pathways are channeled (directly transferred) between enzymes. Both glycolytic and gluconeogenic flux in permeabilized PCMV were sensitive to the presence of exogenous ATP and NAD. It was most interesting that a major product of [1-(13)C]FBP metabolism in permeabilized PCMV was [3-(13)C]lactate, in direct contrast to our previous findings in intact PCMV. Thus disruption of the plasma membrane altered the distribution of substrates between the glycolytic and gluconeogenic pathways. These data suggest that organization of the plasma membrane into distinct microdomains plays an important role in sorting intermediates between the glycolytic and gluconeogenic pathways in intact cells.
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Affiliation(s)
- P G Lloyd
- Department of Physiology, University of Missouri-Columbia, Columbia, Missouri 65212, USA
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39
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Smart EJ, Graf GA, McNiven MA, Sessa WC, Engelman JA, Scherer PE, Okamoto T, Lisanti MP. Caveolins, liquid-ordered domains, and signal transduction. Mol Cell Biol 1999; 19:7289-304. [PMID: 10523618 PMCID: PMC84723 DOI: 10.1128/mcb.19.11.7289] [Citation(s) in RCA: 782] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- E J Smart
- University of Kentucky, Department of Physiology, Lexington, Kentucky 40536, USA
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40
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Galbiati F, Volonte D, Engelman JA, Scherer PE, Lisanti MP. Targeted down-regulation of caveolin-3 is sufficient to inhibit myotube formation in differentiating C2C12 myoblasts. Transient activation of p38 mitogen-activated protein kinase is required for induction of caveolin-3 expression and subsequent myotube formation. J Biol Chem 1999; 274:30315-21. [PMID: 10514527 DOI: 10.1074/jbc.274.42.30315] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Caveolin-3 is the principal structural protein of caveolae membrane domains in striated muscle cells. Caveolin-3 mRNA and protein expression are dramatically induced during the differentiation of C2C12 skeletal myoblasts, coincident with myoblast fusion. In these myotubes, caveolin-3 localizes to the sarcolemma (muscle cell plasma membrane), where it associates with the dystrophin-glycoprotein complex. However, it remains unknown what role caveolin-3 plays in myoblast differentiation and myotube formation. Here, we employ an antisense approach to derive stable C2C12 myoblasts that fail to express the caveolin-3 protein. We show that C2C12 cells harboring caveolin-3 antisense undergo differentiation and express normal amounts of four muscle-specific marker proteins. However, C2C12 cells harboring caveolin-3 antisense fail to undergo myoblast fusion and, therefore, do not form myotubes. Interestingly, treatment with specific p38 mitogen-activated protein kinase inhibitors blocks both myotube formation and caveolin-3 expression, but does not affect the expression of other muscle-specific proteins. In addition, we find that three human rhabdomyosarcoma cell lines do not express caveolin-3 and fail to undergo myoblast fusion. Taken together, these results support the idea that caveolin-3 expression is required for myoblast fusion and myotube formation, and suggest that p38 is an upstream regulator of caveolin-3 expression.
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Affiliation(s)
- F Galbiati
- Department of Molecular Pharmacology, Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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41
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Abstract
Identification of new genes involved in muscle disorders has dramatically changed the traditional clinical classification of the large and heterogeneous group of the muscular dystrophies. Results obtained in recent years by positional candidate cloning have demonstrated the role of the sarcolemma and of the nuclear envelope in normal muscle function and have elucidated molecular pathways perturbed by mutations that lead to muscular dystrophy.
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Affiliation(s)
- D Toniolo
- Institute of Genetics Biochemistry and Evolution - Consiglio Nazionale Ricerche Via Abbiategrasso 207, 27100, Pavia, Italy.
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42
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Engelman JA, Zhang X, Galbiati F, Volonte D, Sotgia F, Pestell RG, Minetti C, Scherer PE, Okamoto T, Lisanti MP. Molecular genetics of the caveolin gene family: implications for human cancers, diabetes, Alzheimer disease, and muscular dystrophy. Am J Hum Genet 1998; 63:1578-87. [PMID: 9837809 PMCID: PMC1377628 DOI: 10.1086/302172] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- J A Engelman
- Department of Molecular Pharmacology, Albert Einstein Cancer Center, Bronx, NY 10461, USA
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43
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Abumrad N, Harmon C, Ibrahimi A. Membrane transport of long-chain fatty acids: evidence for a facilitated process. J Lipid Res 1998. [DOI: 10.1016/s0022-2275(20)33310-1] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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44
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Yamamoto M, Toya Y, Schwencke C, Lisanti MP, Myers MG, Ishikawa Y. Caveolin is an activator of insulin receptor signaling. J Biol Chem 1998; 273:26962-8. [PMID: 9756945 DOI: 10.1074/jbc.273.41.26962] [Citation(s) in RCA: 231] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Recent data have demonstrated that caveolin, a major structural protein of caveolae, negatively regulates signaling molecules localized to caveolae. The interaction of caveolin with several caveolae-associated signaling proteins is mediated by the binding of the scaffolding region of caveolin to a hydrophobic amino acid-containing region within the regulated proteins. The presence of a similar motif within the insulin receptor kinase prompted us to investigate the caveolar localization and regulation of the insulin receptor by caveolin. We found that overexpression of caveolin-3 augmented insulin-stimulated phosphorylation of insulin receptor substrate-1 in 293T cells but not the phosphorylation of insulin receptor. Peptides corresponding to the scaffolding domain of caveolin potently stimulated insulin receptor kinase activity toward insulin receptor substrate-1 or a Src-derived peptide in vitro and in a caveolin subtype-dependent fashion. Peptides from caveolin-2 exhibited no effect, whereas caveolin-1 and -3 stimulated activity 10- and 17-fold, respectively. Peptides which increased insulin receptor kinase activity did so without affecting insulin receptor auto-phosphorylation. Furthermore, the insulin receptor bound to immobilized caveolin peptides, and this binding was inhibited in the presence of free caveolin-3 peptides. Thus, we have identified a novel mechanism by which the insulin receptor is bound and activated by specific caveolin subtypes. Furthermore, these data define a new role for caveolin as an activator of signaling.
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Affiliation(s)
- M Yamamoto
- Cardiovascular and Pulmonary Research Institute, Allegheny University of the Health Sciences, Pittsburgh, Pennsylvania 15212, USA
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45
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Abstract
The density of skeletal muscle caveolae is increased in Duchenne muscular dystrophy and its genetic homologue, the mdx mouse. This structural change is significant as it may indicate muscle regeneration. We identified in mdx mouse tibialis anterior muscles significantly increased levels of caveolin-3, the chief protein in muscle caveolae, and reduced levels of neuronal nitric oxide synthase, an enzyme regulated by caveolin-3. Similar changes occurred in the corresponding mRNA levels. These data suggest that induction of caveolin-3 occurs and this may at least partly be responsible for increased number of caveolae, altered nNOS-caveolin cycle, and regeneration of dystrophic muscles.
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Affiliation(s)
- P L Vaghy
- Department of Medical Biochemistry, College of Medicine, The Ohio State University, Columbus 43210, USA.
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46
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Okamoto T, Schlegel A, Scherer PE, Lisanti MP. Caveolins, a family of scaffolding proteins for organizing "preassembled signaling complexes" at the plasma membrane. J Biol Chem 1998; 273:5419-22. [PMID: 9488658 DOI: 10.1074/jbc.273.10.5419] [Citation(s) in RCA: 1172] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- T Okamoto
- Department of Neurosciences, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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