1
|
Doncheva AI, Li Y, Khanal P, Hjorth M, Kolset SO, Norheim FA, Kimmel AR, Dalen KT. Altered hepatic lipid droplet morphology and lipid metabolism in fasted Plin2-null mice. J Lipid Res 2023; 64:100461. [PMID: 37844775 PMCID: PMC10716011 DOI: 10.1016/j.jlr.2023.100461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/04/2023] [Accepted: 10/05/2023] [Indexed: 10/18/2023] Open
Abstract
Perilipin 2 (Plin2) binds to the surface of hepatic lipid droplets (LDs) with expression levels that correlate with triacylglyceride (TAG) content. We investigated if Plin2 is important for hepatic LD storage in fasted or high-fat diet-induced obese Plin2+/+ and Plin2-/- mice. Plin2-/- mice had comparable body weights, metabolic phenotype, glucose tolerance, and circulating TAG and total cholesterol levels compared with Plin2+/+ mice, regardless of the dietary regime. Both fasted and high-fat fed Plin2-/- mice stored reduced levels of hepatic TAG compared with Plin2+/+ mice. Fasted Plin2-/- mice stored fewer but larger hepatic LDs compared with Plin2+/+ mice. Detailed hepatic lipid analysis showed substantial reductions in accumulated TAG species in fasted Plin2-/- mice compared with Plin2+/+ mice, whereas cholesteryl esters and phosphatidylcholines were increased. RNA-Seq revealed minor differences in hepatic gene expression between fed Plin2+/+ and Plin2-/- mice, in contrast to marked differences in gene expression between fasted Plin2+/+ and Plin2-/- mice. Our findings demonstrate that Plin2 is required to regulate hepatic LD size and storage of neutral lipid species in the fasted state, while its role in obesity-induced steatosis is less clear.
Collapse
Affiliation(s)
- Atanaska I Doncheva
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Yuchuan Li
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway; Department of Hepato-Pancreato-Biliary Surgery, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Prabhat Khanal
- Faculty of Biosciences and Aquaculture, Nord University, Steinkjer, Norway
| | - Marit Hjorth
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Svein O Kolset
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Frode A Norheim
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD, USA
| | - Knut Tomas Dalen
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway; The Norwegian Transgenic Center, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
| |
Collapse
|
2
|
Intra- and Interspecies RNA-Seq Based Variants in the Lactation Process of Ruminants. Animals (Basel) 2022; 12:ani12243592. [PMID: 36552512 PMCID: PMC9774614 DOI: 10.3390/ani12243592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 11/07/2022] [Accepted: 12/16/2022] [Indexed: 12/23/2022] Open
Abstract
The RNA-Seq data provides new opportunities for the detection of transcriptome variants' single nucleotide polymorphisms (SNPs) in various species and tissues. Herein, milk samples from two sheep breeds and two cow breeds were utilized to characterize the genetic variation in the coding regions in three stages (before-peak (BP), peak (P), and after-peak (AP)) of the lactation process. In sheep breeds Assaf and Churra, 100,462 and 97,768, 65,996 and 62,161, and 78,656 and 39,245 variants were observed for BP, P, and AP lactation stages, respectively. The number of specific variants was 59,798 and 76,419, 11,483 and 49,210, and 104,033 and 320,817 in cow breeds Jersy and Kashmiri, respectively, for BP, P, and AP stages. Via the transcriptome analysis of variation in regions containing QTL for fat, protein percentages, and milk yield, we detected a number of pathways and genes harboring mutations that could influence milk production attributes. Many SNPs detected here can be regarded as appropriate markers for custom SNP arrays or genotyping platforms to conduct association analyses among commercial populations. The results of this study offer new insights into milk production genetic mechanisms in cow and sheep breeds, which can contribute to designing suitable breeding systems for optimal milk production.
Collapse
|
3
|
Schratter M, Lass A, Radner FPW. ABHD5-A Regulator of Lipid Metabolism Essential for Diverse Cellular Functions. Metabolites 2022; 12:1015. [PMID: 36355098 PMCID: PMC9694394 DOI: 10.3390/metabo12111015] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/19/2022] [Accepted: 10/23/2022] [Indexed: 11/12/2023] Open
Abstract
The α/β-Hydrolase domain-containing protein 5 (ABHD5; also known as comparative gene identification-58, or CGI-58) is the causative gene of the Chanarin-Dorfman syndrome (CDS), a disorder mainly characterized by systemic triacylglycerol accumulation and a severe defect in skin barrier function. The clinical phenotype of CDS patients and the characterization of global and tissue-specific ABHD5-deficient mouse strains have demonstrated that ABHD5 is a crucial regulator of lipid and energy homeostasis in various tissues. Although ABHD5 lacks intrinsic hydrolase activity, it functions as a co-activating enzyme of the patatin-like phospholipase domain-containing (PNPLA) protein family that is involved in triacylglycerol and glycerophospholipid, as well as sphingolipid and retinyl ester metabolism. Moreover, ABHD5 interacts with perilipins (PLINs) and fatty acid-binding proteins (FABPs), which are important regulators of lipid homeostasis in adipose and non-adipose tissues. This review focuses on the multifaceted role of ABHD5 in modulating the function of key enzymes in lipid metabolism.
Collapse
Affiliation(s)
- Margarita Schratter
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Achim Lass
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, 8010 Graz, Austria
| | - Franz P. W. Radner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| |
Collapse
|
4
|
Leitner N, Hlavatý J, Ertl R, Gabner S, Fuchs-Baumgartinger A, Walter I. Lipid droplets and perilipins in canine osteosarcoma. Investigations on tumor tissue, 2D and 3D cell culture models. Vet Res Commun 2022; 46:1175-1193. [PMID: 35834072 DOI: 10.1007/s11259-022-09975-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/08/2022] [Indexed: 10/17/2022]
Abstract
Lipid droplets were identified as important players in biological processes of various tumor types. With emphasis on lipid droplet-coating proteins (perilipins, PLINs), this study intended to shed light on the presence and formation of lipid droplets in canine osteosarcoma. For this purpose, canine osteosarcoma tissue samples (n = 11) were analyzed via immunohistochemistry and electron microscopy for lipid droplets and lipid droplet-coating proteins (PLINs). Additionally, we used the canine osteosarcoma cell lines D-17 and COS4288 in 2D monolayer and 3D spheroid (cultivated for 7, 14, and 21 days) in vitro models, and further analyzed the samples by means of histochemistry, immunofluorescence, molecular biological techniques (RT-qPCR, Western Blot) and electron microscopical imaging. Lipid droplets, PLIN2, and PLIN3 were detected in osteosarcoma tissue samples as well as in 2D and 3D cultivated D-17 and COS4288 cells. In spheroids, specific distribution patterns of lipid droplets and perilipins were identified, taking into consideration cell line specific zonal apportionment. Upon external lipid supplementation (oleic acid), a rise of lipid droplet amount accompanied with an increase of PLIN2 expression was observed. Detailed electron microscopical analyzes revealed that lipid droplet sizes in tumor tissue were comparable to that of 3D spheroid models. Moreover, the biggest lipid droplets were found in the central zone of the spheroids at all sampling time-points, reaching their maximum size at 21 days. Thus, the 3D spheroids can be considered as a relevant in vitro model for further studies focusing on lipid droplets biology and function in osteosarcoma.
Collapse
Affiliation(s)
- N Leitner
- Institute of Morphology, Working Group Histology, University of Veterinary Medicine, Veterinaerplatz 1, A-1210, Vienna, Austria
| | - J Hlavatý
- Institute of Morphology, Working Group Histology, University of Veterinary Medicine, Veterinaerplatz 1, A-1210, Vienna, Austria
| | - R Ertl
- VetCore Facility for Research, University of Veterinary Medicine, Veterinaerplatz 1, A-1210, Vienna, Austria
| | - S Gabner
- Institute of Morphology, Working Group Histology, University of Veterinary Medicine, Veterinaerplatz 1, A-1210, Vienna, Austria
| | - A Fuchs-Baumgartinger
- Institute of Pathology, University of Veterinary Medicine, Veterinaerplatz 1, A-1210, Vienna, Austria
| | - Ingrid Walter
- Institute of Morphology, Working Group Histology, University of Veterinary Medicine, Veterinaerplatz 1, A-1210, Vienna, Austria. .,VetCore Facility for Research, University of Veterinary Medicine, Veterinaerplatz 1, A-1210, Vienna, Austria.
| |
Collapse
|
5
|
Dai W, White R, Liu J, Liu H. Organelles coordinate milk production and secretion during lactation: Insights into mammary pathologies. Prog Lipid Res 2022; 86:101159. [PMID: 35276245 DOI: 10.1016/j.plipres.2022.101159] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 02/21/2022] [Accepted: 03/03/2022] [Indexed: 12/15/2022]
Abstract
The mammary gland undergoes a spectacular series of changes during its development and maintains a remarkable capacity to remodel and regenerate during progression through the lactation cycle. This flexibility of the mammary gland requires coordination of multiple processes including cell proliferation, differentiation, regeneration, stress response, immune activity, and metabolic changes under the control of diverse cellular and hormonal signaling pathways. The lactating mammary epithelium orchestrates synthesis and apical secretion of macromolecules including milk lipids, milk proteins, and lactose as well as other minor nutrients that constitute milk. Knowledge about the subcellular compartmentalization of these metabolic and signaling events, as they relate to milk production and secretion during lactation, is expanding. Here we review how major organelles (endoplasmic reticulum, Golgi apparatus, mitochondrion, lysosome, and exosome) within mammary epithelial cells collaborate to initiate, mediate, and maintain lactation, and how study of these organelles provides insight into options to maintain mammary/breast health.
Collapse
Affiliation(s)
- Wenting Dai
- College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Robin White
- Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24060, USA
| | - Jianxin Liu
- College of Animal Sciences, Zhejiang University, Hangzhou, China
| | - Hongyun Liu
- College of Animal Sciences, Zhejiang University, Hangzhou, China.
| |
Collapse
|
6
|
Lu Y, Zhou T, Xu C, Wang R, Feng D, Li J, Wang X, Kong Y, Hu G, Kong X, Lu P. Occludin is a target of Src kinase and promotes lipid secretion by binding to BTN1a1 and XOR. PLoS Biol 2022; 20:e3001518. [PMID: 35041644 PMCID: PMC8797263 DOI: 10.1371/journal.pbio.3001518] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 01/28/2022] [Accepted: 12/19/2021] [Indexed: 11/29/2022] Open
Abstract
Lipid droplets (LDs) have increasingly been recognized as an essential organelle for eukaryotes. Although the biochemistry of lipid synthesis and degradation is well characterized, the regulation of LD dynamics, including its formation, maintenance, and secretion, is poorly understood. Here, we report that mice lacking Occludin (Ocln) show defective lipid metabolism. We show that LDs were larger than normal along its biogenesis and secretion pathway in Ocln null mammary cells. This defect in LD size control did not result from abnormal lipid synthesis or degradation; rather, it was because of secretion failure during the lactation stage. We found that OCLN was located on the LD membrane and was bound to essential regulators of lipid secretion, including BTN1a1 and XOR, in a C-terminus–dependent manner. Finally, OCLN was a phosphorylation target of Src kinase, whose loss causes lactation failure. Together, we demonstrate that Ocln is a downstream target of Src kinase and promotes LD secretion by binding to BTN1a1 and XOR. Lipid droplets are an essential eukaryotic organelle, but how they are secreted has remained unclear. This study shows that the tight junction protein Occludin is a phosphorylation target of Src kinase; Occludin binds to BTN1A1 and XOR to facilitate lipid droplet secretion in mammary epithelial cells.
Collapse
Affiliation(s)
- Yunzhe Lu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Tao Zhou
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chongshen Xu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Rui Wang
- Molecular Imaging Core Facility, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Deyi Feng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jiyong Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xu Wang
- Institute of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Yu Kong
- Institute of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Guohong Hu
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xiangyin Kong
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Pengfei Lu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- * E-mail:
| |
Collapse
|
7
|
Analysis of Whole Genome Resequencing Datasets from a Worldwide Sample of Sheep Breeds to Identify Potential Causal Mutations Influencing Milk Composition Traits. Animals (Basel) 2020; 10:ani10091542. [PMID: 32882861 PMCID: PMC7552124 DOI: 10.3390/ani10091542] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/21/2020] [Accepted: 08/28/2020] [Indexed: 01/30/2023] Open
Abstract
Different studies have shown that polymorphisms in the sequence of genes coding for the milk proteins and milk fatty acids are associated with milk composition traits as well as with cheese-making traits. However, the lack of coincident results across sheep populations has prevented the use of this information in sheep breeding programs. The main objective of this study was to exploit the information derived from a total of 175 whole genome resequencing (WGR) datasets from 43 domestic sheep breeds and three wild sheep to evaluate the genetic diversity of 24 candidate genes for milk composition and identify genetic variants with a potential phenotypic effect. The functional annotation of the identified variants highlighted five single nucleotide polymorphisms (SNPs) predicted to have a high impact on the protein function and 42 missense SNPs with a putative deleterious effect. When comparing the allelic frequencies at these 47 polymorphisms with relevant functional effects between the genomes of Assaf and Churra sheep breeds, two missense deleterious variants were identified as potential markers associated to the milk composition differences found between the Churra and Assaf: XDH:92215727C>T and LALBA:137390760T>C. Future research is required to confirm the effect of the potential functionally relevant variants identified in the present study on milk composition and cheese-making traits.
Collapse
|
8
|
Marina H, Reverter A, Gutiérrez-Gil B, Alexandre PA, Porto-Neto LR, Suárez-Vega A, Li Y, Esteban-Blanco C, Arranz JJ. Gene Networks Driving Genetic Variation in Milk and Cheese-Making Traits of Spanish Assaf Sheep. Genes (Basel) 2020; 11:genes11070715. [PMID: 32605032 PMCID: PMC7397207 DOI: 10.3390/genes11070715] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 06/22/2020] [Accepted: 06/25/2020] [Indexed: 02/04/2023] Open
Abstract
Most of the milk produced by sheep is used for the production of high-quality cheese. Consequently, traits related to milk coagulation properties and cheese yield are economically important to the Spanish dairy industry. The present study aims to identify candidate genes and their regulators related to 14 milk and cheese-making traits and to develop a low-density panel of markers that could be used to predict an individual's genetic potential for cheese-making efficiency. In this study, we performed a combination of the classical genome-wide association study (GWAS) with a stepwise regression method and a pleiotropy analysis to determine the best combination of the variants located within the confidence intervals of the potential candidate genes that may explain the greatest genetic variance for milk and cheese-making traits. Two gene networks related to milk and cheese-making traits were created using the genomic relationship matrices built through a stepwise multiple regression approach. Several co-associated genes in these networks are involved in biological processes previously found to be associated with milk synthesis and cheese-making efficiency. The methodology applied in this study enabled the selection of a co-association network comprised of 374 variants located in the surrounding of genes showing a potential influence on milk synthesis and cheese-making efficiency.
Collapse
Affiliation(s)
- Héctor Marina
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain; (H.M.); (B.G.-G.); (A.S.-V.); (C.E.-B.)
| | - Antonio Reverter
- CSIRO Agriculture and Food, Queensland Bioscience Precinct, 306 Carmody Rd., St Lucia, Brisbane, Queensland 4067, Australia; (A.R.); (P.A.A.); (L.R.P.-N.); (Y.L.)
| | - Beatriz Gutiérrez-Gil
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain; (H.M.); (B.G.-G.); (A.S.-V.); (C.E.-B.)
| | - Pâmela Almeida Alexandre
- CSIRO Agriculture and Food, Queensland Bioscience Precinct, 306 Carmody Rd., St Lucia, Brisbane, Queensland 4067, Australia; (A.R.); (P.A.A.); (L.R.P.-N.); (Y.L.)
| | - Laercio R. Porto-Neto
- CSIRO Agriculture and Food, Queensland Bioscience Precinct, 306 Carmody Rd., St Lucia, Brisbane, Queensland 4067, Australia; (A.R.); (P.A.A.); (L.R.P.-N.); (Y.L.)
| | - Aroa Suárez-Vega
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain; (H.M.); (B.G.-G.); (A.S.-V.); (C.E.-B.)
| | - Yutao Li
- CSIRO Agriculture and Food, Queensland Bioscience Precinct, 306 Carmody Rd., St Lucia, Brisbane, Queensland 4067, Australia; (A.R.); (P.A.A.); (L.R.P.-N.); (Y.L.)
| | - Cristina Esteban-Blanco
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain; (H.M.); (B.G.-G.); (A.S.-V.); (C.E.-B.)
| | - Juan-José Arranz
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain; (H.M.); (B.G.-G.); (A.S.-V.); (C.E.-B.)
- Correspondence: ; Tel.: +34-987-291-470
| |
Collapse
|
9
|
Yang M, Deng W, Cao X, Wang L, Yu N, Zheng Y, Wu J, Wu R, Yue X. Quantitative Phosphoproteomics of Milk Fat Globule Membrane in Human Colostrum and Mature Milk: New Insights into Changes in Protein Phosphorylation during Lactation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:4546-4556. [PMID: 32208690 DOI: 10.1021/acs.jafc.9b06850] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Phosphorylation is a widespread posttranslational protein modification and is important in various biological processes. However, milk fat globule membrane (MFGM) phosphoproteins have not been explored systematically in human milk. Here, we used quantitative phosphoproteomics to analyze phosphorylation sites in human MFGM proteins and their differences at different stages of lactation; 305 phosphorylation sites on 170 proteins and 269 phosphorylation sites on 170 proteins were identified in colostrum and mature MFGM, respectively. Among these, 71 phosphorylation sites on 48 proteins were differentially expressed between the different stages of lactation. Osteopontin in human MFGM was the most heavily phosphorylated protein, with a total of 39 identified phosphorylation sites. Our results shed light on phosphorylation sites, composition, and biological functions of MFGM phosphoproteins in human colostrum and mature milk, and provide novel insights into the crucial roles of protein phosphorylation during infant development.
Collapse
Affiliation(s)
- Mei Yang
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China
| | - Wei Deng
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China
| | - Xueyan Cao
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China
| | - Lijie Wang
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China
| | - Na Yu
- Liaoning General Fair Testing Company, Ltd, Shenyang 110026, China
| | - Yan Zheng
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China
| | - Junrui Wu
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China
| | - Rina Wu
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China
| | - Xiqing Yue
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China
| |
Collapse
|
10
|
Adipophilin and perilipin 3 positively correlate with total lipid content in human breast milk. Sci Rep 2020; 10:360. [PMID: 31941931 PMCID: PMC6962152 DOI: 10.1038/s41598-019-57241-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 12/20/2019] [Indexed: 02/06/2023] Open
Abstract
Lipids are secreted into milk as bilayer-coated structures: milk fat globules (MFGs). Adipophilin (ADRP) and perilipin 3 (TIP47) are associated with MFGs in human breast milk; however, the role of these proteins in milk lipid secretion is not fully understood. The study aimed to investigate levels of ADRP, TIP47 and total lipid content in human breast milk, their mutual correlations, and dynamics during lactation. Milk samples from 22 healthy lactating women (Caucasian, Central European) were collected at five time points during lactation (1–3, 12–14, 29–30, 88–90 and 178–180 days postpartum). Mass spectrometry-based method was used for quantification of ADRP and TIP47 in the samples. The gravimetric method was used to determine milk total lipid content. We observed distinctive trends in ADRP, TIP47 levels and lipid content in human breast milk during the first six months of lactation. We also found a significant association between lipid content and ADRP, lipid content and TIP47, and ADRP and TIP47 concentrations in breast milk at all sampling points. A mass spectrometry-based method was developed for quantifying ADRP and TIP47 in human breast milk. Strong mutual correlations were found between ADRP, TIP47 and total lipid content in human breast milk.
Collapse
|
11
|
|
12
|
Redwan EM, Alkarim SA, El-Hanafy AA, Saad YM, Almehdar HA, Uversky VN. Disorder in milk proteins: adipophilin and TIP47, important constituents of the milk fat globule membrane. J Biomol Struct Dyn 2019; 38:1214-1229. [PMID: 30896308 DOI: 10.1080/07391102.2019.1592027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Milk fat globules (MFGs), which are secreted by the epithelial cells of the lactating mammary glands, account for the most of the nutritional value of milk. They are enveloped by the milk fat globule membrane (MFGM), a complex structure consisting of three phospholipid membrane monolayers and containing various lipids. Depending on the origin of milk, specific proteins accounts for 5-70% of the MFGM mass. Proteome of MFGMs includes hundreds of proteins, with nine major components being adipophilin, butyrophilin, cluster of differentiation 36, fatty acid binding protein, lactadherin, mucin 1, mucin 15, tail-interacting protein 47 (TIP47), and xanthine oxidoreductase. Two of the MFGM components, adipophilin and TIP47, belong to the five-member perilipin family of lipid droplet proteins. Adipophilin is involved in the formation of cytoplasmic lipid droplets and secretion of MFGs. This protein is also related to the formation of other lipid droplets that exist in most cell types, playing an important role in the transport of lipids from ER to the surface of lipid droplets. TIP47 acts as a cytoplasmic sorting factor for mannose 6-phosphate receptors and is recruited to the MFGM. Therefore, both adipophilin and TIP47 are moonlighting proteins, each possessing several unrelated functions. This review focuses on the main functions and specific structural features of adipophilin and TIP47, analyzes similarities and differences of these proteins among different species, and describes these proteins in the context of other members of the perilipin family.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Elrashdy M Redwan
- Biological Sciences Department, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.,Protein Research Department, Therapeutic and Protective Proteins Laboratory, Genetic Engineering and Biotechnology Research Institute, City for Scientific Research and Technology Applications, Alexandria, Egypt
| | - Saleh A Alkarim
- Biological Sciences Department, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Amr A El-Hanafy
- Biological Sciences Department, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Nucleic Acid Research, Genetic Engineering and Biotechnology Research Institute, City for Scientific Research & Technology Applications, Borg EL-Arab, Alexandria, Egypt
| | - Yasser M Saad
- Biological Sciences Department, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.,Genetics Laboratory, National Institute of Oceanography and Fisheries, Cairo, Egypt
| | - Hussein A Almehdar
- Biological Sciences Department, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Vladimir N Uversky
- Biological Sciences Department, Faculty of Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.,Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Russia Moscow Region.,Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| |
Collapse
|
13
|
Yang D, Huynh H, Wan Y. Milk lipid regulation at the maternal-offspring interface. Semin Cell Dev Biol 2018; 81:141-148. [PMID: 29051053 PMCID: PMC5916746 DOI: 10.1016/j.semcdb.2017.10.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 10/12/2017] [Indexed: 12/19/2022]
Abstract
Milk lipids provide a large proportion of energy, nutrients, essential fatty acids, and signaling molecules for the newborns, the synthesis of which is a tightly controlled process. Dysregulated milk lipid production and composition may be detrimental to the growth, development, health and survival of the newborns. Many genetically modified animal models have contributed to our understanding of milk lipid regulation in the lactating mammary gland. In this review, we discuss recent advances in our knowledge of the mechanisms that control milk lipid biosynthesis and secretion during lactation, and how maternal genetic and dietary defects impact milk lipid composition and consequently offspring traits.
Collapse
Affiliation(s)
- Dengbao Yang
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - HoangDinh Huynh
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yihong Wan
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| |
Collapse
|
14
|
Sztalryd C, Brasaemle DL. The perilipin family of lipid droplet proteins: Gatekeepers of intracellular lipolysis. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1221-1232. [PMID: 28754637 DOI: 10.1016/j.bbalip.2017.07.009] [Citation(s) in RCA: 319] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 12/21/2022]
Abstract
Lipid droplets in chordates are decorated by two or more members of the perilipin family of lipid droplet surface proteins. The perilipins sequester lipids by protecting lipid droplets from lipase action. Their relative expression and protective nature is adapted to the balance of lipid storage and utilization in specific cells. Most cells of the body have tiny lipid droplets with perilipins 2 and 3 at the surfaces, whereas specialized fat-storing cells with larger lipid droplets also express perilipins 1, 4, and/or 5. Perilipins 1, 2, and 5 modulate lipolysis by controlling the access of lipases and co-factors of lipases to substrate lipids stored within lipid droplets. Although perilipin 2 is relatively permissive to lipolysis, perilipins 1 and 5 have distinct control mechanisms that are altered by phosphorylation. Here we evaluate recent progress toward understanding functions of the perilipins with a focus on their role in regulating lipolysis and autophagy. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
Collapse
Affiliation(s)
- Carole Sztalryd
- Department of Medicine, Division of Endocrinology, School of Medicine, University of Maryland, Baltimore, MD, USA; Geriatric Research, Education, and Clinical Center, Baltimore Veterans Affairs Health Care Center, Baltimore, MD, USA.
| | - Dawn L Brasaemle
- Department of Nutritional Sciences and Center for Lipid Research, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA.
| |
Collapse
|
15
|
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: 168] [Impact Index Per Article: 24.0] [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.
Collapse
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;
| |
Collapse
|
16
|
Suárez-Vega A, Gutiérrez-Gil B, Klopp C, Tosser-Klopp G, Arranz JJ. Variant discovery in the sheep milk transcriptome using RNA sequencing. BMC Genomics 2017; 18:170. [PMID: 28202015 PMCID: PMC5312585 DOI: 10.1186/s12864-017-3581-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 02/10/2017] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The identification of genetic variation underlying desired phenotypes is one of the main challenges of current livestock genetic research. High-throughput transcriptome sequencing (RNA-Seq) offers new opportunities for the detection of transcriptome variants (SNPs and short indels) in different tissues and species. In this study, we used RNA-Seq on Milk Sheep Somatic Cells (MSCs) with the goal of characterizing the genetic variation within the coding regions of the milk transcriptome in Churra and Assaf sheep, two common dairy sheep breeds farmed in Spain. RESULTS A total of 216,637 variants were detected in the MSCs transcriptome of the eight ewes analyzed. Among them, a total of 57,795 variants were detected in the regions harboring Quantitative Trait Loci (QTL) for milk yield, protein percentage and fat percentage, of which 21.44% were novel variants. Among the total variants detected, 561 (2.52%) and 1,649 (7.42%) were predicted to produce high or moderate impact changes in the corresponding transcriptional unit, respectively. In the functional enrichment analysis of the genes positioned within selected QTL regions harboring novel relevant functional variants (high and moderate impact), the KEGG pathway with the highest enrichment was "protein processing in endoplasmic reticulum". Additionally, a total of 504 and 1,063 variants were identified in the genes encoding principal milk proteins and molecules involved in the lipid metabolism, respectively. Of these variants, 20 mutations were found to have putative relevant effects on the encoded proteins. CONCLUSIONS We present herein the first transcriptomic approach aimed at identifying genetic variants of the genes expressed in the lactating mammary gland of sheep. Through the transcriptome analysis of variability within regions harboring QTL for milk yield, protein percentage and fat percentage, we have found several pathways and genes that harbor mutations that could affect dairy production traits. Moreover, remarkable variants were also found in candidate genes coding for major milk proteins and proteins related to milk fat metabolism. Several of the SNPs found in this study could be included as suitable markers in genotyping platforms or custom SNP arrays to perform association analyses in commercial populations and apply genomic selection protocols in the dairy production industry.
Collapse
Affiliation(s)
- Aroa Suárez-Vega
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, León, 24071, Spain
| | - Beatriz Gutiérrez-Gil
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, León, 24071, Spain
| | - Christophe Klopp
- INRA, Plateforme bioinformatique Toulouse Midi-Pyrénées, UR875 Biométrie et Intelligence Artificielle, BP 52627, 31326, Castanet-Tolosan Cedex, France
| | | | - Juan José Arranz
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, León, 24071, Spain.
| |
Collapse
|
17
|
Libby AE, Bales E, Orlicky DJ, McManaman JL. Perilipin-2 Deletion Impairs Hepatic Lipid Accumulation by Interfering with Sterol Regulatory Element-binding Protein (SREBP) Activation and Altering the Hepatic Lipidome. J Biol Chem 2016; 291:24231-24246. [PMID: 27679530 DOI: 10.1074/jbc.m116.759795] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Indexed: 12/16/2022] Open
Abstract
Perilipin-2 (PLIN2) is a constitutively associated cytoplasmic lipid droplet coat protein that has been implicated in fatty liver formation in non-alcoholic fatty liver disease. Mice with or without whole-body deletion of perilipin-2 (Plin2-null) were fed either Western or control diets for 30 weeks. Perilipin-2 deletion prevents obesity and insulin resistance in Western diet-fed mice and dramatically reduces hepatic triglyceride and cholesterol levels in mice fed Western or control diets. Gene and protein expression studies reveal that PLIN2 deletion suppressed SREBP-1 and SREBP-2 target genes involved in de novo lipogenesis and cholesterol biosynthetic pathways in livers of mice on either diet. GC-MS lipidomics demonstrate that this reduction correlated with profound alterations in the hepatic lipidome with significant reductions in both desaturation and elongation of hepatic neutral lipid species. To examine the possibility that lipidomic actions of PLIN2 deletion contribute to suppression of SREBP activation, we isolated endoplasmic reticulum membrane fractions from long-term Western diet-fed wild type (WT) and Plin2-null mice. Lipidomic analyses reveal that endoplasmic reticulum membranes from Plin2-null mice are markedly enriched in ω-3 and ω-6 long-chain polyunsaturated fatty acids, which others have shown inhibit SREBP activation and de novo lipogenesis. Our results identify PLIN2 as a determinant of global changes in the hepatic lipidome and suggest the hypothesis that these actions contribute to SREBP-regulated de novo lipogenesis involved in non-alcoholic fatty liver disease.
Collapse
Affiliation(s)
- Andrew E Libby
- From the Integrated Physiology Graduate Program.,Division of Reproductive Sciences, and
| | | | - David J Orlicky
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - James L McManaman
- From the Integrated Physiology Graduate Program, .,Division of Reproductive Sciences, and
| |
Collapse
|
18
|
Liu X, Yao Z. Chronic over-nutrition and dysregulation of GSK3 in diseases. Nutr Metab (Lond) 2016; 13:49. [PMID: 27493677 PMCID: PMC4972972 DOI: 10.1186/s12986-016-0108-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 07/21/2016] [Indexed: 12/16/2022] Open
Abstract
Loss of cellular response to hormonal regulation in maintaining metabolic homeostasis is common in the process of aging. Chronic over-nutrition may render cells insensitive to such a hormonal regulation owing to overstimulation of certain signaling pathways, thus accelerating aging and causing diseases. The glycogen synthase kinase 3 (GSK3) plays a pivotal role in relaying various extracellular and intracellular regulatory signals critical to cell growth, survival, regeneration, or death. The main signaling pathway regulating GSK3 activity through serine-phosphorylation is the phosphoinositide 3-kinase (PI3K)/phosphoinositide-dependent kinase-1 (PDK1)/Akt relay that catalyzes serine-phosphorylation and thus inactivation of GSK3. In addition, perilipin 2 (PLIN2) has recently been shown to regulate GSK3 activation through direct association with GSK3. This review summarizes current understanding on environmental and nutritional factors contributing to GSK3 regulation (or dysregulation) through the PI3K/PDK1/Akt/GSK3 axis, and highlights the newly discovered role that PLIN2 plays in regulating GSK3 activity and GSK3 downstream pathways.
Collapse
Affiliation(s)
- Xunxian Liu
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5 Canada
| | - Zemin Yao
- Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5 Canada
| |
Collapse
|
19
|
Lv Y, Guan W, Qiao H, Wang C, Chen F, Zhang Y, Liao Z. Veterinary Medicine and Omics (Veterinomics): Metabolic Transition of Milk Triacylglycerol Synthesis in Sows from Late Pregnancy to Lactation. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2016; 19:602-16. [PMID: 26484979 DOI: 10.1089/omi.2015.0102] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Mammalian milk is a key source of lipids, providing not only important calories but also essential fatty acids. Veterinary medicine and omics systems sciences intersection, termed as "veterinomics" here, has received little attention to date but stands to offer much promise for building bridges between human and animal health. We determined the changes in porcine mammary genes and proteomics expression associated with milk triacylglycerol (TAG) synthesis and secretion from late pregnancy to lactation. TAG content and fatty acid (FA) composition were determined in porcine colostrum (the 1st day of lactation) and milk (the 17th day of lactation). The mammary transcriptome for 70 genes and 13 proteins involved in TAG synthesis and secretion from six sows, each at d -17(late pregnancy), d 1(early lactation), and d 17 (peak lactation) relative to parturition were analyzed using quantitative real-time PCR and Western blot analyses. The TAG content and the concentrations of de novo synthesized FAs, saturated FAs, and monounsaturated FAs were higher in milk than in colostrum (p<0.05). Robust upregulation with high relative mRNA abundance was evident during lactation for genes associated with FA uptake (VLDLR, LPL, CD36), FA activation (ACSS2, ACSL3), and intracellar transport (FABP3), de novo FA synthesis (ACACA, FASN), FA elongation (ELOVL1), FA desaturation (SCD, FADS1), TAG synthesis (GPAM, AGPAT1, LPIN1, DGAT1), lipid droplet formation (BTN2A1, XDH, PLIN2), and transcription factors and nuclear receptors (SREBP1, SCAP, INSIG1/2). In conclusion, a wide variety of lipogenic genes and proteins regulate the channeling of FAs towards milk TAG synthesis and secretion in porcine mammary gland tissue. These findings inform future omics strategies to increase milk fat production and lipid profile and attest to the rise of both veterinomics and lipidomics in postgenomics life sciences.
Collapse
Affiliation(s)
- Yantao Lv
- 1 College of Animal Science, South China Agricultural University , Guangzhou, People's Republic of China
| | - Wutai Guan
- 1 College of Animal Science, South China Agricultural University , Guangzhou, People's Republic of China .,2 National Engineering Research Center for Breeding Swine Industry , Guangzhou, People's Republic of China
| | - Hanzhen Qiao
- 1 College of Animal Science, South China Agricultural University , Guangzhou, People's Republic of China
| | - Chaoxian Wang
- 1 College of Animal Science, South China Agricultural University , Guangzhou, People's Republic of China
| | - Fang Chen
- 1 College of Animal Science, South China Agricultural University , Guangzhou, People's Republic of China
| | - Yinzhi Zhang
- 1 College of Animal Science, South China Agricultural University , Guangzhou, People's Republic of China
| | - Zhichao Liao
- 1 College of Animal Science, South China Agricultural University , Guangzhou, People's Republic of China
| |
Collapse
|
20
|
Abstract
Spaceflight affects numerous organ systems in the body, leading to metabolic dysfunction that may have long-term consequences. Microgravity-induced alterations in liver metabolism, particularly with respect to lipids, remain largely unexplored. Here we utilize a novel systems biology approach, combining metabolomics and transcriptomics with advanced Raman microscopy, to investigate altered hepatic lipid metabolism in mice following short duration spaceflight. Mice flown aboard Space Transportation System -135, the last Shuttle mission, lose weight but redistribute lipids, particularly to the liver. Intriguingly, spaceflight mice lose retinol from lipid droplets. Both mRNA and metabolite changes suggest the retinol loss is linked to activation of PPARα-mediated pathways and potentially to hepatic stellate cell activation, both of which may be coincident with increased bile acids and early signs of liver injury. Although the 13-day flight duration is too short for frank fibrosis to develop, the retinol loss plus changes in markers of extracellular matrix remodeling raise the concern that longer duration exposure to the space environment may result in progressive liver damage, increasing the risk for nonalcoholic fatty liver disease.
Collapse
|
21
|
Zambonelli P, Gaffo E, Zappaterra M, Bortoluzzi S, Davoli R. Transcriptional profiling of subcutaneous adipose tissue in Italian Large White pigs divergent for backfat thickness. Anim Genet 2016; 47:306-23. [PMID: 26931818 DOI: 10.1111/age.12413] [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] [Accepted: 12/08/2015] [Indexed: 12/30/2022]
Abstract
Fat deposition is a widely studied trait in pigs because of its implications with animal growth efficiency, technological and nutritional characteristics of meat products, but the global framework of the biological and molecular processes regulating fat deposition in pigs is still incomplete. This study describes the backfat tissue transcription profile in Italian Large White pigs and reports genes differentially expressed between fat and lean animals according to RNA-seq data. The backfat transcription profile was characterised by the expression of 23 483 genes, of which 54.1% were represented by known genes. Of 63 418 expressed transcripts, about 80% were non-previously annotated isoforms. By comparing the expression level of fat vs. lean pigs, we detected 86 robust differentially expressed transcripts, 72 more highly expressed (e.g. ACP5, BCL2A1, CCR1, CD163, CD1A, EGR2, ENPP1, GPNMB, INHBB, LYZ, MSR1, OLR1, PIK3AP1, PLIN2, SPP1, SLC11A1, STC1) and 14 lower expressed (e.g. ADSSL1, CDO1, DNAJB1, HSPA1A, HSPA1B, HSPA2, HSPB8, IGFBP5, OLFML3) in fat pigs. The main functional categories enriched in differentially expressed genes were immune system process, response to stimulus, cell activation and skeletal system development, for the overexpressed genes, and unfolded protein binding and stress response, for the underexpressed genes, which included five heat shock proteins. Adipose tissue alterations and impaired stress response are linked to inflammation and, in turn, to adipose tissue secretory activity, similar to what is observed in human obesity. Our results provide the opportunity to identify biomarkers of carcass fat traits to improve the pig production chain and to identify genetic factors that regulate the observed differential expression.
Collapse
Affiliation(s)
- P Zambonelli
- Department of Agricultural and-Food Sciences (DISTAL), Bologna University, Via Fratelli Rosselli 107, 42123, Reggio Emilia, Italy
| | - E Gaffo
- Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35121, Padova, Italy
| | - M Zappaterra
- Department of Agricultural and-Food Sciences (DISTAL), Bologna University, Via Fratelli Rosselli 107, 42123, Reggio Emilia, Italy
| | - S Bortoluzzi
- Department of Molecular Medicine, University of Padova, Via Gabelli 63, 35121, Padova, Italy
| | - R Davoli
- Department of Agricultural and-Food Sciences (DISTAL), Bologna University, Via Fratelli Rosselli 107, 42123, Reggio Emilia, Italy
| |
Collapse
|
22
|
Takahashi Y, Shinoda A, Kamada H, Shimizu M, Inoue J, Sato R. Perilipin2 plays a positive role in adipocytes during lipolysis by escaping proteasomal degradation. Sci Rep 2016; 6:20975. [PMID: 26876687 PMCID: PMC4753471 DOI: 10.1038/srep20975] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 01/14/2016] [Indexed: 12/18/2022] Open
Abstract
Perilipin2 (Plin2), also known as adipose differentiation-related protein (ADRP), or adipophilin, is a member of the PAT family involved in lipid droplet (LD) formation in the liver and peripheral tissues. Although Plin2 was originally identified as a highly expressed gene in adipocytes, its physiological role in mature adipocytes is largely unknown. In this report, we investigated the regulation of Plin2 expression and its function in differentiated adipocytes of mouse embryonic fibroblasts (MEFs). Plin2 mRNA levels increased during adipocyte differentiation whereas protein levels did not. Plin2 was degraded through the ubiquitin-proteasome pathway but was inhibited by lipolytic inducers. Furthermore, lentiviral-mediated Plin2 knockdown attenuated lipolysis in differentiated MEFs in a time-dependent manner. Oleic acid-induced LD formation enhanced Plin2 protein stability when it was localized to LDs. Furthermore, a mutational analysis revealed that the ubiquitination and degradation of Plin2 required both the second and third alanine in the N-terminal region. These results suggest that Plin2 is degraded in the cytosol in its N-terminal amino acid sequence-dependent manner and instead becomes stable when localized on LDs. Our findings highlight the relationship between protein stability and a previously unnoticed function of Plin2 during lipolysis in adipocytes.
Collapse
Affiliation(s)
- Yu Takahashi
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Akihiro Shinoda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Haruhiko Kamada
- Laboratory of Biopharmaceutical Research, National Institute of Biomedical Innovation, Osaka, Japan.,The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka, Japan
| | - Makoto Shimizu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Jun Inoue
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Ryuichiro Sato
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
23
|
Natural Functions of PLIN2 Mediating Wnt/LiCl Signaling and Glycogen Synthase Kinase 3 (GSK3)/GSK3 Substrate-Related Effects Are Modulated by Lipid. Mol Cell Biol 2015; 36:421-37. [PMID: 26598603 DOI: 10.1128/mcb.00510-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 10/02/2015] [Indexed: 12/28/2022] Open
Abstract
Belonging to the PLIN family, PLIN2 associates with lipid storage droplets (LSDs), but other functions of PLIN2 remain unclear. Here, we suggest that PLIN2 mediates Wnt signaling because PLIN2 small interfering RNA (siRNA) suppresses activation of Wnt/coreceptor pathways. The mediation in the Wnt/Frizzled pathway seems to occur from Dishevelleds to axin/glycogen synthase kinase 3(GSK3)/β-catenin complexes (AGβC) as Wnt decreases Dishevelled/PLIN2 but increases AGβC/PLIN2 associations. Augmenting cellular LSDs that affect PLIN2 associations with these proteins, oleic acid (OA) treatment inhibits Wnt-increased AGβC/PLIN2 associations and β-catenin T-cell factor signaling (β-CTS). Revealing that PLIN2 is a GSK3-associated protein, the study explored PLIN2-mediated effects on GSK3/GSK3 substrates. PLIN2 siRNA reduces inhibitory GSK3 levels and lithium chloride (LiCl)-upregulated β-catenin or CCAAT/enhancer binding protein α (c/EBPα) expression. OA treatment decreases LiCl-increased c/EBPα via PLIN2-c/EBPα dissociation. In addition to PLIN2 overexpression increasing β-CTS, PLIN2 depletion or overexpression drops or adds expression of GSK3 substrates, such as β-catenin, c/EBPα,c-Myc, cyclin D1, and insulin receptor substrate 1, and cell growth/survival. PLIN2 N or C terminus overexpression that is associated with higher levels of the substrates suggests that those substrates bind to specific regions of PLIN2. Mimicking the possible high lipid concentrations in cells in the human body under conditions of hyperlipidemia/obesity, OA-treated cells gain or reduce GSK3 substrate expression in parallel with a decrease (a Wnt-like effect) or increase in GSK3 activity, likely regulated by GSK3/PLIN2/GSK3 substrate associations.
Collapse
|
24
|
Prokesch A, Smorlesi A, Perugini J, Manieri M, Ciarmela P, Mondini E, Trajanoski Z, Kristiansen K, Giordano A, Bogner-Strauss JG, Cinti S. Molecular aspects of adipoepithelial transdifferentiation in mouse mammary gland. Stem Cells 2015; 32:2756-66. [PMID: 24898182 DOI: 10.1002/stem.1756] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/28/2014] [Accepted: 04/20/2014] [Indexed: 01/09/2023]
Abstract
The circular, reversible conversion of the mammary gland during pregnancy and involution is a paradigm of physiological tissue plasticity. The two most prominent cell types in mammary gland, adipocytes and epithelial cells, interact in an orchestrated way to coordinate this process. Previously, we showed that this conversion is at least partly achieved by reciprocal transdifferentiation between mammary adipocytes and lobulo-alveolar epithelial cells. Here, we aim to shed more light on the regulators of mammary transdifferentiation. Using immunohistochemistry with cell type-specific lipid droplet-coating markers (Perilipin1 and 2), we show that cells with an intermediate adipoepithelial phenotype exist during and after pregnancy. Nuclei of cells with similar transitional structural characteristics are highly positive for Elf5, a master regulator of alveologenesis. In cultured adipocytes, we could show that transient and stable ectopic expression of Elf5 induces expression of the milk component whey acidic protein, although the general adipocyte phenotype is not affected suggesting that additional pioneering factors are necessary. Furthermore, the lack of transdifferentiation of adipocytes during pregnancy after clearing of the epithelial compartment indicates that transdifferentiation signals must emanate from the epithelial part. To explore candidate genes potentially involved in the transdifferentiation process, we devised a high-throughput gene expression study to compare cleared mammary fat pads with developing, contralateral controls at several time points during pregnancy. Incorporation of bioinformatic predictions of secretory proteins provides new insights into possible paracrine signaling pathways and downstream transdifferentiation factors. We discuss a potential role for osteopontin (secreted phosphoprotein 1 [Spp1]) signaling through integrins to induce adipoepithelial transdifferentiation.
Collapse
Affiliation(s)
- A Prokesch
- Institute for Genomics and Bioinformatics, Graz University of Technology, Petersgasse, Graz, Austria; Institute of Biochemistry, Graz University of Technology, Petersgasse, Graz, Austria
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Saben JL, Bales ES, Jackman MR, Orlicky D, MacLean PS, McManaman JL. Maternal obesity reduces milk lipid production in lactating mice by inhibiting acetyl-CoA carboxylase and impairing fatty acid synthesis. PLoS One 2014; 9:e98066. [PMID: 24849657 PMCID: PMC4029960 DOI: 10.1371/journal.pone.0098066] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 04/25/2014] [Indexed: 12/21/2022] Open
Abstract
Maternal metabolic and nutrient trafficking adaptations to lactation differ among lean and obese mice fed a high fat (HF) diet. Obesity is thought to impair milk lipid production, in part, by decreasing trafficking of dietary and de novo synthesized lipids to the mammary gland. Here, we report that de novo lipogenesis regulatory mechanisms are disrupted in mammary glands of lactating HF-fed obese (HF-Ob) mice. HF feeding decreased the total levels of acetyl-CoA carboxylase-1 (ACC), and this effect was exacerbated in obese mice. The relative levels of phosphorylated (inactive) ACC, were elevated in the epithelium, and decreased in the adipose stroma, of mammary tissue from HF-Ob mice compared to those of HF-fed lean (HF-Ln) mice. Mammary gland levels of AMP-activated protein kinase (AMPK), which catalyzes formation of inactive ACC, were also selectively elevated in mammary glands of HF-Ob relative to HF-Ln dams or to low fat fed dams. These responses correlated with evidence of increased lipid retention in mammary adipose, and decreased lipid levels in mammary epithelial cells, of HF-Ob dams. Collectively, our data suggests that maternal obesity impairs milk lipid production, in part, by disrupting the balance of de novo lipid synthesis in the epithelial and adipose stromal compartments of mammary tissue through processes that appear to be related to increased mammary gland AMPK activity, ACC inhibition, and decreased fatty acid synthesis.
Collapse
Affiliation(s)
- Jessica L. Saben
- Division of Basic Reproductive Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Graduate Program in Reproductive Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Elise S. Bales
- Division of Basic Reproductive Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Matthew R. Jackman
- Center for Human Nutrition, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - David Orlicky
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Paul S. MacLean
- Center for Human Nutrition, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - James L. McManaman
- Division of Basic Reproductive Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Graduate Program in Reproductive Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Center for Human Nutrition, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- * E-mail:
| |
Collapse
|
26
|
Kohjima M, Tsai TH, Tackett BC, Thevananther S, Li L, Chang BHJ, Chan L. Delayed liver regeneration after partial hepatectomy in adipose differentiation related protein-null mice. J Hepatol 2013; 59:1246-54. [PMID: 23928401 PMCID: PMC4001732 DOI: 10.1016/j.jhep.2013.07.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 07/19/2013] [Accepted: 07/22/2013] [Indexed: 12/04/2022]
Abstract
BACKGROUND & AIMS Adult hepatocytes undergo cell cycle progression and proliferation in response to partial hepatectomy (PH). Transient lipid accumulation within hepatocytes preceding the peak proliferative phase is a characteristic feature of regenerating livers. However, the molecular mediators and mechanisms responsible for lipid accumulation in regenerating livers are not well understood. Adipose differentiation related protein (ADRP; Plin2) regulates hepatic triglyceride storage and Plin2-deficient (Plin2(-/-)) mice have significantly reduced triglyceride (TG) content in the liver. We sought to determine the functional significance of PLIN2 in liver regeneration in response to PH and toxic liver injury and examined whether absence of Plin2 expression modulates hepatocyte proliferation and liver regeneration. METHODS We subjected wild-type (WT) and Plin2(-/-) mice to 70% PH or acute carbon tetrachloride (CCL4) treatment and examined the hepatic lipid content, the expression profile of lipid metabolism-related genes, the rate of cellular proliferation and the dynamics of liver regeneration in the treated animals. RESULTS In response to PH, Plin2(-/-) mice showed decreased hepatic triglyceride accumulation and delayed cell cycle progression, which was associated with impaired liver regeneration. Fatty acid (FA) synthesis and lipid transfer gene expression profile were comparable between Plin2(-/-) and wild-type mice, while VLDL secretion rate was higher in the Plin2(-/-) mice. Downregulated β-oxidation and reduced cytosolic FA level in Plin2(-/-) mice may have contributed to the attenuation of the liver regeneration capacity in these animals. In parallel experiments, we also observed attenuated hepatic lipid accumulation and proliferation in response to CCl4-mediated acute toxic liver injury in Plin2(-/-) mice. CONCLUSIONS We conclude that PLIN2-mediated lipid accumulation and utilization by the liver is important for efficient liver regeneration in response to PH and toxic liver injury.
Collapse
Affiliation(s)
- Motoyuki Kohjima
- Diabetes and Endocrinology Research Center and Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Tsung-Huang Tsai
- Diabetes and Endocrinology Research Center and Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Bryan C. Tackett
- Diabetes and Endocrinology Research Center and Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Department of Pediatrics, Section of Gastroenterology, Hepatology and Nutrition, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Sundararajah Thevananther
- Diabetes and Endocrinology Research Center and Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Department of Pediatrics, Section of Gastroenterology, Hepatology and Nutrition, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Lan Li
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Benny Hung-Junn Chang
- Diabetes and Endocrinology Research Center and Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Lawrence Chan
- Diabetes and Endocrinology Research Center and Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| |
Collapse
|
27
|
Senthivinayagam S, McIntosh AL, Moon KC, Atshaves BP. Plin2 inhibits cellular glucose uptake through interactions with SNAP23, a SNARE complex protein. PLoS One 2013; 8:e73696. [PMID: 24040030 PMCID: PMC3765312 DOI: 10.1371/journal.pone.0073696] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 07/25/2013] [Indexed: 11/19/2022] Open
Abstract
Although a link between excess lipid storage and aberrant glucose metabolism has been recognized for many years, little is known what role lipid storage droplets and associated proteins such as Plin2 play in managing cellular glucose levels. To address this issue, the influence of Plin2 on glucose uptake was examined using 2-NBD-Glucose and [(3)H]-2-deoxyglucose to show that insulin-mediated glucose uptake was decreased 1.7- and 1.8-fold, respectively in L cell fibroblasts overexpressing Plin2. Conversely, suppression of Plin2 levels by RNAi-mediated knockdown increased 2-NBD-Glucose uptake several fold in transfected L cells and differentiated 3T3-L1 cells. The effect of Plin2 expression on proteins involved in glucose uptake and transport was also examined. Expression of the SNARE protein SNAP23 was increased 1.6-fold while levels of syntaxin-5 were decreased 1.7-fold in Plin2 overexpression cells with no significant changes observed in lipid droplet associated proteins Plin1 or FSP27 or with the insulin receptor, GLUT1, or VAMP4. FRET experiments revealed a close proximity of Plin2 to SNAP23 on lipid droplets to within an intramolecular distance of 51 Å. The extent of targeting of SNAP23 to lipid droplets was determined by co-localization and co-immunoprecipitation experiments to show increased partitioning of SNAP23 to lipid droplets when Plin2 was overexpressed. Taken together, these results suggest that Plin2 inhibits glucose uptake by interacting with, and regulating cellular targeting of SNAP23 to lipid droplets. In summary, the current study for the first time provides direct evidence for the role of Plin2 in mediating cellular glucose uptake.
Collapse
Affiliation(s)
- Subramanian Senthivinayagam
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Avery L. McIntosh
- Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas, United States of America
| | - Kenneth C. Moon
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Barbara P. Atshaves
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
| |
Collapse
|
28
|
Crunk AE, Monks J, Murakami A, Jackman M, MacLean PS, Ladinsky M, Bales ES, Cain S, Orlicky DJ, McManaman JL. Dynamic regulation of hepatic lipid droplet properties by diet. PLoS One 2013; 8:e67631. [PMID: 23874434 PMCID: PMC3708958 DOI: 10.1371/journal.pone.0067631] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 05/20/2013] [Indexed: 12/21/2022] Open
Abstract
Cytoplasmic lipid droplets (CLD) are organelle-like structures that function in neutral lipid storage, transport and metabolism through the actions of specific surface-associated proteins. Although diet and metabolism influence hepatic CLD levels, how they affect CLD protein composition is largely unknown. We used non-biased, shotgun, proteomics in combination with metabolic analysis, quantitative immunoblotting, electron microscopy and confocal imaging to define the effects of low- and high-fat diets on CLD properties in fasted-refed mice. We found that the hepatic CLD proteome is distinct from that of CLD from other mammalian tissues, containing enzymes from multiple metabolic pathways. The hepatic CLD proteome is also differentially affected by dietary fat content and hepatic metabolic status. High fat feeding markedly increased the CLD surface density of perilipin-2, a critical regulator of hepatic neutral lipid storage, whereas it reduced CLD levels of betaine-homocysteine S-methyltransferase, an enzyme regulator of homocysteine levels linked to fatty liver disease and hepatocellular carcinoma. Collectively our data demonstrate that the hepatic CLD proteome is enriched in metabolic enzymes, and that it is qualitatively and quantitatively regulated by diet and metabolism. These findings implicate CLD in the regulation of hepatic metabolic processes, and suggest that their properties undergo reorganization in response to hepatic metabolic demands.
Collapse
Affiliation(s)
- Amanda E. Crunk
- Graduate Program of Molecular Biology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Jenifer Monks
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Aya Murakami
- Graduate Program of Molecular Biology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Matthew Jackman
- Division of Endocrinology and Metabolism, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Center for Human Nutrition, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Colorado Obesity Research Initiative, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Paul S. MacLean
- Division of Endocrinology and Metabolism, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Center for Human Nutrition, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Colorado Obesity Research Initiative, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Mark Ladinsky
- The Boulder Laboratory for 3D Electron Microscopy, University of Colorado Boulder, Boulder Colorado, United States of America
| | - Elise S. Bales
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Shannon Cain
- The Colorado Obesity Research Initiative, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - David J. Orlicky
- Department of Pathology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - James L. McManaman
- Graduate Program of Molecular Biology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Center for Human Nutrition, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- The Colorado Obesity Research Initiative, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- * E-mail:
| |
Collapse
|
29
|
McManaman JL, Bales ES, Orlicky DJ, Jackman M, MacLean PS, Cain S, Crunk AE, Mansur A, Graham CE, Bowman TA, Greenberg AS. Perilipin-2-null mice are protected against diet-induced obesity, adipose inflammation, and fatty liver disease. J Lipid Res 2013; 54:1346-59. [PMID: 23402988 DOI: 10.1194/jlr.m035063] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The cytoplasmic lipid droplet (CLD) protein perilipin-2 (Plin2) is expressed in multiple nonadipose tissues, where it is thought to play a role in regulating their lipid storage properties. However, the extent to which Plin2 functions in nutrient utilization and metabolism, or how it influences the consequences of over-feeding, remains unclear. In this study, we demonstrate that the absence of Plin2 prevents high-fat diet(HFD)-induced obesity in male and female mice. This response is associated with increased formation of subcutaneous beige adipocyte cells with uncoupling protein 1 expression, and amelioration of inflammatory foci formation in white adipose tissue and steatosis in the liver. Experiments demonstrate that Plin2 loss results in reduced energy intake and increased physical activity in response to HFD feeding. Our study provides the first evidence that Plin2 contributes to HFD-induced obesity by modulating food intake, and that its absence prevents obesity-associated adipose tissue inflammatory foci and liver steatosis.
Collapse
Affiliation(s)
- James L McManaman
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, CO, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Abstract
Neonates of most species depend on milk lipids for calories, fat-soluble vitamins, and bioactive lipid components for growth and development during the postnatal period. To meet neonatal nutrition and development needs, the mammary gland has evolved efficient mechanisms for synthesizing and secreting large quantities of lipid during lactation. Although the biochemical steps involved in milk lipid synthesis are understood, the identities of the genes mediating these steps and the molecular physiology of milk lipid production and secretion have only recently begun to be understood in detail through advances in mouse genetics, gene expression analysis, protein structural properties, and the cell biology of lipid metabolism. This review discusses emerging data about the molecular, cellular, and structural determinants of milk lipid synthesis and secretion within the context of physiological functions.
Collapse
Affiliation(s)
- James L McManaman
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, Graduate Programs in Cell Biology, Stem Cells and Development, Molecular Biology and Reproductive Sciences, University of Colorado, School of Medicine, Aurora, CO 80045, USA
| |
Collapse
|
31
|
McIntosh AL, Senthivinayagam S, Moon KC, Gupta S, Lwande JS, Murphy CC, Storey SM, Atshaves BP. Direct interaction of Plin2 with lipids on the surface of lipid droplets: a live cell FRET analysis. Am J Physiol Cell Physiol 2012; 303:C728-42. [PMID: 22744009 DOI: 10.1152/ajpcell.00448.2011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Despite increasing awareness of the health risks associated with excess lipid storage in cells and tissues, knowledge of events governing lipid exchange at the surface of lipid droplets remains unclear. To address this issue, fluorescence resonance energy transfer (FRET) was performed to examine live cell interactions of Plin2 with lipids involved in maintaining lipid droplet structure and function. FRET efficiencies (E) between CFP-labeled Plin2 and fluorescently labeled phosphatidylcholine, sphingomyelin, stearic acid, and cholesterol were quantitated on a pixel-by-pixel basis to generate FRET image maps that specified areas with high E (>60%) in lipid droplets. The mean E and the distance R between the probes indicated a high yield of energy transfer and demonstrated molecular distances on the order of 44-57 Å, in keeping with direct molecular contact. In contrast, FRET between CFP-Plin2 and Nile red was not detected, indicating that the CFP-Plin2/Nile red interaction was beyond FRET proximity (>100 Å). An examination of the effect of Plin2 on cellular metabolism revealed that triacylglycerol, fatty acid, and cholesteryl ester content increased while diacylglycerol remained constant in CFP-Plin2-overexpressing cells. Total phospholipids also increased, reflecting increased phosphatidylcholine and sphingomyelin. Consistent with these results, expression levels of enzymes involved in triacylglycerol, cholesteryl ester, and phospholipid synthesis were significantly upregulated in CFP-Plin2-expressing cells while those associated with lipolysis either decreased or were unaffected. Taken together, these data show for the first time that Plin2 interacts directly with lipids on the surface of lipid droplets and influences levels of key enzymes and lipids involved in maintaining lipid droplet structure and function.
Collapse
Affiliation(s)
- Avery L McIntosh
- Dept. of Biochemistry and Molecular Biology, Michigan State Univ., East Lansing, MI 48824, USA
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
Among organelles, lipid droplets (LDs) uniquely constitute a hydrophobic phase in the aqueous environment of the cytosol. Their hydrophobic core of neutral lipids stores metabolic energy and membrane components, making LDs hubs for lipid metabolism. In addition, LDs are implicated in a number of other cellular functions, ranging from protein storage and degradation to viral replication. These processes are functionally linked to many physiological and pathological conditions, including obesity and related metabolic diseases. Despite their important functions and nearly ubiquitous presence in cells, many aspects of LD biology are unknown. In the past few years, the pace of LD investigation has increased, providing new insights. Here, we review the current knowledge of LD cell biology and its translation to physiology.
Collapse
Affiliation(s)
- Tobias C Walther
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
| | | |
Collapse
|
33
|
Russell TD, Schaack J, Orlicky DJ, Palmer C, Chang BHJ, Chan L, McManaman JL. Adipophilin regulates maturation of cytoplasmic lipid droplets and alveolae in differentiating mammary glands. J Cell Sci 2011; 124:3247-53. [PMID: 21878492 DOI: 10.1242/jcs.082974] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Milk lipids originate by secretion of triglyceride-rich cytoplasmic lipid droplets (CLDs) from mammary epithelial cells. Adipophilin (ADPH)/Plin2, a member of the perilipin family of CLD binding proteins, is hypothesized to regulate CLD production in these cells during differentiation of the mammary gland into a secretory organ. We tested this hypothesis by comparing CLD accumulation in differentiating mammary glands of wild-type and ADPH-deficient mice. ADPH deficiency did not prevent CLD formation; however, it disrupted the increase in CLD size that normally occurs in differentiating mammary epithelial cells. Failure to form large CLDs in ADPH-deficient mice correlated with localization of adipose triglyceride lipase (ATGL) to the CLD surface, suggesting that ADPH promotes CLD growth by inhibiting lipolytic activity. Significantly, mammary alveoli also failed to mature in ADPH-deficient mice, and pups born to these mice failed to survive. The possibility that CLD accumulation and alveolar maturation defects in ADPH-deficient mice are functionally related was tested by in vivo rescue experiments. Transduction of mammary glands of pregnant ADPH-deficient mice with adenovirus encoding ADPH as an N-terminal GFP fusion protein prevented ATGL from localizing to CLDs and rescued CLD size and alveolar maturation defects. Collectively, these data provide direct in vivo evidence that ADPH inhibition of ATGL-dependent lipolysis is required for normal CLD accumulation and alveolar maturation during mammary gland differentiation. We speculate that impairing CLD accumulation interferes with alveolar maturation and lactation by disrupting triglyceride homeostasis in mammary epithelial cells.
Collapse
Affiliation(s)
- Tanya D Russell
- Graduate Program in Molecular Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | | | | | | | | | | | | |
Collapse
|
34
|
Sun Z, Shushanov S, LeRoith D, Wood TL. Decreased IGF type 1 receptor signaling in mammary epithelium during pregnancy leads to reduced proliferation, alveolar differentiation, and expression of insulin receptor substrate (IRS)-1 and IRS-2. Endocrinology 2011; 152:3233-45. [PMID: 21628386 PMCID: PMC3138223 DOI: 10.1210/en.2010-1296] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The IGFs and the IGF type 1 receptor (IGF-1R) are essential mediators of normal mammary gland development in mice. IGF-I and the IGF-1R have demonstrated functions in formation and proliferation of terminal end buds and in ductal outgrowth and branching during puberty. To study the functions of IGF-1R during pregnancy and lactation, we established transgenic mouse lines expressing a human dominant-negative kinase dead IGF-1R (dnhIGF-1R) under the control of the whey acidic protein promoter. We provide evidence that the IGF-1R pathway is necessary for normal epithelial proliferation and alveolar formation during pregnancy. Furthermore, we demonstrate that the whey acidic protein-dnhIGF-1R transgene causes a delay in alveolar differentiation including lipid droplet formation, lumen expansion, and β-casein protein expression. Analysis of IGF-1R signaling pathways showed a decrease in P-IGF-1R and P-Akt resulting from expression of the dnhIGF-1R. We further demonstrate that disruption of the IGF-1R decreases mammary epithelial cell expression of the signaling intermediates insulin receptor substrate (IRS)-1 and IRS-2. No alterations were observed in downstream signaling targets of prolactin and progesterone, suggesting that activation of the IGF-1R may directly regulate expression of IRS-1/2 during alveolar development and differentiation. These data show that IGF-1R signaling is necessary for normal alveolar proliferation and differentiation, in part, through induction of signaling intermediates that mediate alveolar development.
Collapse
Affiliation(s)
- Zhaoyu Sun
- Department Neurology & Neuroscience, Cancer Center H1200, New Jersey Medical School/University of Medicine and Dentistry of New Jersey, 205 South Orange Avenue, Newark, New Jersey 07101-1709, USA
| | | | | | | |
Collapse
|
35
|
Chong BM, Reigan P, Mayle-Combs KD, Orlicky DJ, McManaman JL. Determinants of adipophilin function in milk lipid formation and secretion. Trends Endocrinol Metab 2011; 22:211-7. [PMID: 21592818 PMCID: PMC3118920 DOI: 10.1016/j.tem.2011.04.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 04/02/2011] [Accepted: 04/06/2011] [Indexed: 11/16/2022]
Abstract
In many species the lactating mammary gland is one of the most lipogenic organs of the body. The majority of the lipid produced during lactation is secreted into milk by a novel process of membrane envelopment of cytoplasmic lipid droplets (CLDs). Adipophilin (ADRP/ADPH/PLIN2), a member of the perilipin (PAT) family of lipid droplet proteins, is hypothesized to play a pivotal role in both formation and secretion of milk lipids. Production of milk lipids is the only known example of CLD secretion, and the only process in which PAT family members undergo secretion. This review discusses emerging data on the structural and functional properties of adipophilin that determine its physiological actions and mediate its effects on milk lipid formation and secretion.
Collapse
Affiliation(s)
- Brandi M. Chong
- Graduate Program in Molecular Biology, University of Colorado, Anschutz Medical Campus
- Division of Basic Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado, Anschutz Medical Campus
| | - Philip Reigan
- Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus
| | - Kasey D. Mayle-Combs
- University of Colorado Denver Lab Coats Program, University of Colorado, Anschutz Medical Campus
| | - David J. Orlicky
- Department of Pathology, University of Colorado, Anschutz Medical Campus
| | - James L. McManaman
- Graduate Program in Molecular Biology, University of Colorado, Anschutz Medical Campus
- Division of Basic Reproductive Sciences, Department of Obstetrics and Gynecology, University of Colorado, Anschutz Medical Campus
| |
Collapse
|
36
|
Rudolph MC, Russell TD, Webb P, Neville MC, Anderson SM. Prolactin-mediated regulation of lipid biosynthesis genes in vivo in the lactating mammary epithelial cell. Am J Physiol Endocrinol Metab 2011; 300:E1059-68. [PMID: 21467304 PMCID: PMC3118595 DOI: 10.1152/ajpendo.00083.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prolactin (PRL) is known to play an essential role in mammary alveolar proliferation in the pregnant mouse, but its role in lactation has been more difficult to define. Genetic manipulations that alter expression of the PRL receptor and its downstream signaling molecules resulted in developmental defects that may directly or indirectly impact secretory activation and lactation. To examine the in vivo role of PRL specifically in lactation, bromocriptine (BrCr) was administered every 8 h to lactating mice on the second day postpartum, resulting in an ~95% decrease in serum PRL levels. Although morphological changes in secretory alveoli were slight, by 8 h of BrCr, pup growth was inhibited significantly. Phosphorylated STAT5 fell to undetectable levels within 4 h. Decreased milk protein gene expression, β-casein, and α-lactalbumin, was observed after 8 h of treatment. To assess mammary-specific effects on lipid synthesis genes, we isolated mammary epithelial cells (MECs) depleted of mammary adipocytes. Expression of genes involved in glucose uptake, glycolysis, pentose phosphate shunt, de novo synthesis of fatty acids, and biosynthesis of triacylglycerides was decreased up to 19-fold in MECs by just 8 h of BrCr treatment. Glands from BrCr-treated mice showed a twofold reduction in intracellular cytoplasmic lipid droplets and a reduction in cytosolic β-casein. These data demonstrate that PRL signaling regulates MEC-specific lipogenic gene expression and that PRL signals coordinate the milk synthesis and mammary epithelial cell survival during lactation in the mouse.
Collapse
Affiliation(s)
- Michael C Rudolph
- Department of Pathology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO 80045, USA.
| | | | | | | | | |
Collapse
|
37
|
Orban T, Palczewska G, Palczewski K. Retinyl ester storage particles (retinosomes) from the retinal pigmented epithelium resemble lipid droplets in other tissues. J Biol Chem 2011; 286:17248-58. [PMID: 21454509 DOI: 10.1074/jbc.m110.195198] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Levels of many hydrophobic cellular substances are tightly regulated because of their potential cytotoxicity. These compounds tend to self-aggregate in cytoplasmic storage depots termed lipid droplets/bodies that have well defined structures that contain additional components, including cholesterol and various proteins. Hydrophobic substances in these structures become mobilized in a specific and regulated manner as dictated by cellular requirements. Retinal pigmented epithelial cells in the eye produce retinyl ester-containing lipid droplets named retinosomes. These esters are mobilized to replenish the visual chromophore, 11-cis-retinal, and their storage ensures proper visual function despite fluctuations in dietary vitamin A intake. But it remains unclear whether retinosomes are structures specific to the eye or similar to lipid droplets in other organs/tissues that contain substances other than retinyl esters. Thus, we initially investigated the production of these lipid droplets in experimental cell lines expressing lecithin:retinol acyltransferase, a key enzyme involved in formation of retinyl ester-containing retinosomes from all-trans-retinol. We found that retinosomes and oleate-derived lipid droplets form and co-localize concomitantly, indicating their intrinsic structural similarities. Next, we isolated native retinosomes from bovine retinal pigmented epithelium and found that their protein and hydrophobic small molecular constituents were similar to those of lipid droplets reported for other experimental cell lines and tissues. These unexpected findings suggest a common mechanism for lipid droplet formation that exhibits broad chemical specificity for the hydrophobic substances being stored.
Collapse
Affiliation(s)
- Tivadar Orban
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | | | | |
Collapse
|
38
|
Chong BM, Russell TD, Schaack J, Orlicky DJ, Reigan P, Ladinsky M, McManaman JL. The adipophilin C terminus is a self-folding membrane-binding domain that is important for milk lipid secretion. J Biol Chem 2011; 286:23254-65. [PMID: 21383012 DOI: 10.1074/jbc.m110.217091] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytoplasmic lipid droplets (CLD) in mammary epithelial cells undergo secretion by a unique membrane envelopment process to produce milk lipids. Adipophilin (ADPH/Plin2), a member of the perilipin/PAT family of lipid droplet-associated proteins, is hypothesized to mediate CLD secretion through interactions with apical plasma membrane elements. We found that the secretion of CLD coated by truncated ADPH lacking the C-terminal region encoding a putative four-helix bundle structure was impaired relative to that of CLD coated by full-length ADPH. We used homology modeling and analyses of the solution and membrane binding properties of purified recombinant ADPH C terminus to understand how this region possibly mediates CLD secretion. Homology modeling supports the concept that the ADPH C terminus forms a four-helix bundle motif and suggests that this structure can form stable membrane bilayer interactions. Circular dichroism and protease mapping studies confirmed that the ADPH C terminus is an independently folding α-helical structure that is relatively resistant to urea denaturation. Liposome binding studies showed that the purified C terminus binds to phospholipid membranes through electrostatic dependent interactions, and cell culture studies documented that it localizes to the plasma membrane. Collectively, these data provide direct evidence that the ADPH C terminus forms a stable membrane binding helical structure that is important for CLD secretion. We speculate that interactions between the four-helix bundle of ADPH and membrane phospholipids may be an initial step in milk lipid secretion.
Collapse
Affiliation(s)
- Brandi M Chong
- Graduate Program in Molecular Biology, Division of Basic Reproductive Science, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | | | | | | | | | | | | |
Collapse
|
39
|
Abstract
The lipid droplet (LD), an organelle that exists ubiquitously in various organisms, from bacteria to mammals, has attracted much attention from both medical and cell biology fields. The LD in white adipocytes is often treated as the prototype LD, but is rather a special example, considering that its size, intracellular localization and molecular composition are vastly different from those of non-adipocyte LDs. These differences confer distinct properties on adipocyte and non-adipocyte LDs. In this article, we address the current understanding of LDs by discussing the differences between adipocyte and non-adipocyte LDs.
Collapse
Affiliation(s)
- Michitaka Suzuki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | | | | | | |
Collapse
|
40
|
Chang BHJ, Li L, Saha P, Chan L. Absence of adipose differentiation related protein upregulates hepatic VLDL secretion, relieves hepatosteatosis, and improves whole body insulin resistance in leptin-deficient mice. J Lipid Res 2010; 51:2132-42. [PMID: 20424269 DOI: 10.1194/jlr.m004515] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We previously showed that adipose differentiation related protein (Adfp)-deficient mice display a 60% reduction in hepatic triglyceride (TG) content. In this study, we investigated the role of ADFP in lipid and glucose homeostasis in a genetic obesity model, Lep(ob/ob) mice. We bred Adfp(-/-) mice with Lep(ob/ob) mice to create Lep(ob/ob)/Adfp(-/-) and Lep(ob/ob)/Adfp(+/+) mice and analyzed the hepatic lipids, lipid droplet (LD) morphology, LD protein composition and distribution, lipogenic gene expression, and VLDL secretion, as well as insulin sensitivity of the two groups of mice. Compared with Lep(ob/ob)/Adfp(+/+) mice, Lep(ob/ob)/Adfp(-/-) mice displayed an increased VLDL secretion rate, a 25% reduction in hepatic TG associated with improvement in fatty liver grossly and microscopically with a change of the size of LDs in a proportion of the hepatocytes and a redistribution of major LD-associated proteins from the cytoplasmic compartment to the LD surface. There was no detectable change in lipogenic gene expression. Lep(ob/ob)/Adfp(-/-) mice also had improved glucose tolerance and insulin sensitivity in both liver and muscle. The alteration of LD size in the liver of Lep(ob/ob)/Adfp(-/-) mice despite the relocation of other LDPs to the LD indicates a nonredundant role for ADFP in determining the size and distribution of hepatic LDs.
Collapse
|
41
|
de Wilde J, Smit E, Snepvangers FJM, de Wit NWJ, Mohren R, Hulshof MFM, Mariman ECM. Adipophilin protein expression in muscle--a possible protective role against insulin resistance. FEBS J 2009; 277:761-73. [PMID: 20030713 DOI: 10.1111/j.1742-4658.2009.07525.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adipophilin is a 50 kDa protein that belongs to the PAT family (perilipin, adipophilin, TIP47, S3-12 and OXPAT), which comprises proteins involved in the coating of lipid droplets. Little is known about the functional role of adipophilin in muscle. Using the C2C12 cell line as a model, we demonstrate that palmitic acid-treated cells highly express the adipophilin protein in a dose-dependent way. Next, we show that oleic acid is a more potent inducer of adipophilin protein levels than palmitic acid. Cells treated with oleic acid have a higher adipophilin protein expression and higher triglyceride levels but less impairment of insulin signaling than cells treated with palmitic acid. Additionally, we show that peroxisome proliferator-activated receptor (PPAR)alpha, PPARbeta/delta and PPARgamma agonists all increase the expression of the adipophilin protein in C2C12 cells. This effect was most pronounced for the PPARalpha agonist GW7647. Furthermore, the expression of adipophilin as a 37 kDa N-terminally truncated protein is higher in the gastrocnemius than in the quadriceps of C57BL/6J mice, especially after an 8-week high-fat diet. The expression of adipophilin was higher in the muscle of mice fed a 4-week high-fat diet based on olive oil or safflower oil than in mice fed a 4-week high-fat diet based on palm oil. After 2 weeks of intervention, plasma glucose, plasma insulin and the homeostasis model assessment of insulin resistance index were lower in mice fed a 4-week high-fat diet based on olive oil or safflower oil than in mice fed a 4-week high-fat diet based on palm oil. Taken together, the results obtained in the present study indicate that adipophilin protein expression in muscle is involved in maintaining insulin sensitivity.
Collapse
Affiliation(s)
- Janneke de Wilde
- Nutrigenomics Consortium, Top Institute Food and Nutrition, Wageningen, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
42
|
Olofsson SO, Boström P, Andersson L, Li L, Højlund K, Adiels M, Perkins R, Borén J. Lipid droplets and their role in the development of insulin resistance and diabetic dyslipidemia. ACTA ACUST UNITED AC 2009. [DOI: 10.2217/clp.09.54] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
43
|
Lee B, Zhu J, Wolins NE, Cheng JX, Buhman KK. Differential association of adipophilin and TIP47 proteins with cytoplasmic lipid droplets in mouse enterocytes during dietary fat absorption. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:1173-80. [PMID: 19698802 DOI: 10.1016/j.bbalip.2009.08.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 07/29/2009] [Accepted: 08/10/2009] [Indexed: 01/22/2023]
Abstract
Recently, we found that enterocytes dynamically store triglycerides (TGs) in cytoplasmic lipid droplets (CLDs) during dietary fat absorption. A dynamic pool of TG in the form of CLDs which expands and depletes relative to time post dietary fat challenge is present in the absorptive cells of the small intestine, enterocytes. To identify cellular factors which may play a role in the regulation of this dynamic process we investigated the expression and localization of a lipid droplet associated protein family, PAT proteins, in enterocytes of mice chronically and acutely challenged by dietary fat. We found that adipophilin and Tip47 are the only PAT genes present in mouse intestinal mucosa and both genes are present at higher levels after high-fat challenges. We found TIP47 protein present in the intestine from chow and high-fat challenged mice; however, adipophilin protein was only present after high-fat challenges. In addition, TIP47 protein level was higher after an acute than a chronic high-fat challenge whereas adipophilin protein level was higher after a chronic than an acute high-fat challenge. We co-imaged TG in CLDs using CARS microscopy and TIP47 or adipophilin using immunocytochemistry in isolated enterocytes from mice challenged chronically and acutely by high levels of dietary fat. TIP47, but not adipophilin, coats CLDs in enterocytes after an acute high-fat challenge suggesting that TIP47 plays a role in the synthesis of CLDs from newly synthesized TG at the beginning of the process of dietary fat absorption in enterocytes. Adipophilin, on the other hand, coats CLDs only in enterocytes of chronic high-fat fed mice suggesting that adipophilin may play a role in the stabilization of TG stored in CLDs in longer term. These results suggest distinct roles for TIP47 and adipophilin in dietary fat absorption.
Collapse
Affiliation(s)
- Bonggi Lee
- Department of Foods and Nutrition, Purdue University, 700 W. State Street, West Lafayette, IN 47907-2059, USA
| | | | | | | | | |
Collapse
|
44
|
Abstract
Lipids, primarily triglycerides, are major milk constituents of most mammals, providing a large percentage of calories, essential fatty acids and bioactive lipids required for neonatal growth and development. To meet the caloric and nutritional demands of newborns, the mammary glands of most species have evolved an enormous capacity to synthesize and secrete large quantities of lipids during lactation. Significant information exists regarding the physiological regulation of lipid metabolism in the mammary gland from the study of dairy animals. However, detailed understanding of the molecular mechanisms regulating milk lipid formation is only now coming into focus through advances in mouse genetics, global analysis of mammary gland gene expression, organelle protein properties and the cell biology of lipid metabolism.
Collapse
Affiliation(s)
- James L McManaman
- Department of Obstetrics & Gynecology, University of Colorado - Denver, Anschutz Medical Campus, 12800 East 19th, PO Box 6511, Aurora, CO 80045, USA, Tel.: +1 303 724 3500
| |
Collapse
|
45
|
PAT proteins, an ancient family of lipid droplet proteins that regulate cellular lipid stores. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:419-40. [PMID: 19375517 DOI: 10.1016/j.bbalip.2009.04.002] [Citation(s) in RCA: 494] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 02/24/2009] [Accepted: 04/08/2009] [Indexed: 02/07/2023]
Abstract
The PAT family of lipid droplet proteins includes 5 members in mammals: perilipin, adipose differentiation-related protein (ADRP), tail-interacting protein of 47 kDa (TIP47), S3-12, and OXPAT. Members of this family are also present in evolutionarily distant organisms, including insects, slime molds and fungi. All PAT proteins share sequence similarity and the ability to bind intracellular lipid droplets, either constitutively or in response to metabolic stimuli, such as increased lipid flux into or out of lipid droplets. Positioned at the lipid droplet surface, PAT proteins manage access of other proteins (lipases) to the lipid esters within the lipid droplet core and can interact with cellular machinery important for lipid droplet biogenesis. Genetic variations in the gene for the best-characterized of the mammalian PAT proteins, perilipin, have been associated with metabolic phenotypes, including type 2 diabetes mellitus and obesity. In this review, we discuss how the PAT proteins regulate cellular lipid metabolism both in mammals and in model organisms.
Collapse
|
46
|
Varela GM, Antwi DA, Dhir R, Yin X, Singhal NS, Graham MJ, Crooke RM, Ahima RS. Inhibition of ADRP prevents diet-induced insulin resistance. Am J Physiol Gastrointest Liver Physiol 2008; 295:G621-8. [PMID: 18669627 PMCID: PMC2536783 DOI: 10.1152/ajpgi.90204.2008] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Diets with high fat content induce steatosis, insulin resistance, and type 2 diabetes. The lipid droplet protein adipose differentiation-related protein (ADRP) mediates hepatic steatosis, but whether this affects insulin action in the liver or peripheral organs in diet-induced obesity is uncertain. We fed C57BL/6J mice a high-fat diet and simultaneously treated them with an antisense oligonucleotide (ASO) against ADRP for 4 wk. Glucose homeostasis was assessed with clamp and tracer techniques. ADRP ASO decreased the levels of triglycerides and diacylglycerol in the liver, but fatty acids, long-chain fatty acyl CoAs, ceramides, and cholesterol were unchanged. Insulin action in the liver was enhanced after ADRP ASO treatment, whereas muscle and adipose tissue were not affected. ADRP ASO increased the phosphorylation of insulin receptor substrate (IRS)1, IRS2, and Akt, and decreased gluconeogenic enzymes and PKCepsilon, consistent with its insulin-sensitizing action. These results demonstrate an important role for ADRP in the pathogenesis of diet-induced insulin resistance.
Collapse
Affiliation(s)
- Gladys M. Varela
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and Isis Pharmaceuticals, Carlsbad, California
| | - Daniel A. Antwi
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and Isis Pharmaceuticals, Carlsbad, California
| | - Ravindra Dhir
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and Isis Pharmaceuticals, Carlsbad, California
| | - Xiaoyan Yin
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and Isis Pharmaceuticals, Carlsbad, California
| | - Neel S. Singhal
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and Isis Pharmaceuticals, Carlsbad, California
| | - Mark J. Graham
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and Isis Pharmaceuticals, Carlsbad, California
| | - Roseanne M. Crooke
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and Isis Pharmaceuticals, Carlsbad, California
| | - Rexford S. Ahima
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; and Isis Pharmaceuticals, Carlsbad, California
| |
Collapse
|
47
|
Orlicky DJ, Degala G, Greenwood C, Bales ES, Russell TD, McManaman JL. Multiple functions encoded by the N-terminal PAT domain of adipophilin. J Cell Sci 2008; 121:2921-9. [PMID: 18697835 DOI: 10.1242/jcs.026153] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adipophilin (ADPH), a member of the perilipin family of cytoplasmic lipid droplet (CLD)-binding proteins, is crucially dependent on triglyceride synthesis for stability. We have used cell lines expressing full-length or N-terminally modified forms of ADPH to investigate the role of the N-terminus in regulating ADPH stability and interactions with CLD. Full-length ADPH was unstable and could not be detected on CLDs unless cultures were incubated with oleic acid (OA) to stimulate triglyceride synthesis, or were treated with MG132 to block proteasomal degradation. By contrast, ADPH lacking amino acids 1-89 (Delta 2,3 ADPH), or N-terminally GFP-tagged full-length ADPH, was stable in the absence of OA or MG132, as was the closely related protein TIP47. However, none of these proteins localized to CLDs unless OA was added to the culture medium. Furthermore, immunofluorescence analysis showed that TIP47 localization to CLDs was prevented by full-length ADPH, but not by Delta 2,3 ADPH. These results suggest that the N-terminal region of ADPH mediates proteasomal degradation and access of TIP47 to the CLD surface and possibly contributes to CLD stability. Chimeras of ADPH and TIP47, generated by swapping their N- and C-terminal halves, showed that these properties are specific to ADPH.
Collapse
Affiliation(s)
- David J Orlicky
- Department of Pathology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | | | | | | | | | | |
Collapse
|
48
|
Imanishi Y, Sun W, Maeda T, Maeda A, Palczewski K. Retinyl ester homeostasis in the adipose differentiation-related protein-deficient retina. J Biol Chem 2008; 283:25091-102. [PMID: 18606814 DOI: 10.1074/jbc.m802981200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The retinal pigmented epithelium (RPE) plays an essential role in vision, including storing and converting retinyl esters of the visual chromophore, 11-cis-retinal. Retinyl ester storage structures (RESTs), specialized lipid droplets within the RPE, take up retinyl esters synthesized in the endoplasmic reticulum. Here we report studies of mice lacking exons 2 and 3 of the gene encoding adipose differentiation-related protein (Adfp), a structural component of RESTs. We found that dark adaptation was slower in Adfp(Delta2-3/Delta2-3) than in Adfp+/+ mice and that Adfp(Delta2-3/Delta2-3) mice had consistently delayed clearances of all-trans-retinal and all-trans-retinol from rod photoreceptor cells. Two-photon microscopy revealed aberrant trafficking of all-trans-retinyl esters in the RPE of Adfp(Delta2-3/Delta2-3) mice, a problem caused by abnormal maintenance of RESTs in the dark-adapted state. Retinyl ester accumulation was also reduced in Adfp(Delta2-3/Delta2-3) as compared with Adfp+/+ mice. These observations suggest that Adfp plays a unique role in vision by maintaining proper storage and trafficking of retinoids within the eye.
Collapse
Affiliation(s)
- Yoshikazu Imanishi
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
| | | | | | | | | |
Collapse
|
49
|
Abstract
Organisms store energy for later use during times of nutrient scarcity. Excess energy is stored as triacylglycerol in lipid droplets during lipogenesis. When energy is required, the stored triacylglycerol is hydrolyzed via activation of lipolytic pathways. The coordination of lipid storage and utilization is regulated by the perilipin family of lipid droplet coat proteins [perilipin, adipophilin/adipocyte differentiation-related protein (ADRP), S3-12, tail-interacting protein of 47 kilodaltons (TIP47), and myocardial lipid droplet protein (MLDP)/oxidative tissues-enriched PAT protein (OXPAT)/lipid storage droplet protein 5 (LSDP5)]. Lipid droplets are dynamic and heterogeneous in size, location, and protein content. The proteins that coat lipid droplets change during lipid droplet biogenesis and are dependent upon multiple factors, including tissue-specific expression and metabolic state (basal vs. lipogenic vs. lipolytic). New data suggest that proteins previously implicated in vesicle trafficking, including Rabs, soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs), and motor and cytoskeletal proteins, likely orchestrate the movement and fusion of lipid droplets. Thus, rather than inert cytoplasmic inclusions, lipid droplets are now appreciated as dynamic organelles that are critical for management of cellular lipid stores. That much remains to be discovered is suggested by the recent identification of a novel lipase [adipocyte triglyceride lipase (ATGL)] and lipase regulator [Comparative Gene Identification-58 (CGI-58)], which has led to reconsideration of the decades-old model of lipolysis. Future discovery likely will be driven by the exploitation of model organisms and by human genetic studies.
Collapse
Affiliation(s)
- Nicole A Ducharme
- Center for Diabetes and Obesity Research, Brown Foundation Institute of Molecular Medicine, 1825 Pressler Street, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | | |
Collapse
|
50
|
McManaman JL, Russell TD, Schaack J, Orlicky DJ, Robenek H. Molecular determinants of milk lipid secretion. J Mammary Gland Biol Neoplasia 2007; 12:259-68. [PMID: 17999166 DOI: 10.1007/s10911-007-9053-5] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Accepted: 10/24/2007] [Indexed: 12/20/2022] Open
Abstract
Mammary epithelial cells secrete lipids by an envelopment process that produces lipid droplets coated by membranes derived from the plasma membrane and possibly secretory vesicles. This secretion process, which resembles viral budding, is hypothesized to be mediated by specific interactions between molecules on the surface of intracellular lipids and membrane elements of the cell. Multiple lines of evidence indicate that milk lipid secretion occurs through a tripartite complex between the integral transmembrane protein, butyrophilin (BTN); the soluble metabolic enzyme, xanthine oxidoreductase (XOR); and the lipid droplet surface protein, adipophilin (ADPH). However, topological evidence from freeze-fracture replica immunolabelling (FRIL) challenge this model and suggests that milk lipid secretion is mediated by butyrophilin alone. Advances in our understanding of the molecular, structural, and functional properties of these proteins now make it possible to understand the physiological functions of each of these molecules in detail and to identify the specific molecular determinants that mediate milk lipid secretion.
Collapse
Affiliation(s)
- James L McManaman
- Department of Obstetrics and Gynecology, University of Colorado Denver and Health Sciences Center, Aurora, CO, USA.
| | | | | | | | | |
Collapse
|