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Antwi MB, Dumitriu G, Simón-Santamaria J, Romano JS, Li R, Smedsrød B, Vik A, Eskild W, Sørensen KK. Liver sinusoidal endothelial cells show reduced scavenger function and downregulation of Fc gamma receptor IIb, yet maintain a preserved fenestration in the Glmpgt/gt mouse model of slowly progressing liver fibrosis. PLoS One 2023; 18:e0293526. [PMID: 37910485 PMCID: PMC10619817 DOI: 10.1371/journal.pone.0293526] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 10/16/2023] [Indexed: 11/03/2023] Open
Abstract
Liver sinusoidal endothelial cells (LSECs) are fenestrated endothelial cells with a unique, high endocytic clearance capacity for blood-borne waste macromolecules and colloids. This LSEC scavenger function has been insufficiently characterized in liver disease. The Glmpgt/gt mouse lacks expression of a subunit of the MFSD1/GLMP lysosomal membrane protein transporter complex, is born normal, but soon develops chronic, mild hepatocyte injury, leading to slowly progressing periportal liver fibrosis, and splenomegaly. This study examined how LSEC scavenger function and morphology are affected in the Glmpgt/gt model. FITC-labelled formaldehyde-treated serum albumin (FITC-FSA), a model ligand for LSEC scavenger receptors was administered intravenously into Glmpgt/gt mice, aged 4 months (peak of liver inflammation), 9-10 month, and age-matched Glmpwt/wt mice. Organs were harvested for light and electron microscopy, quantitative image analysis of ligand uptake, collagen accumulation, LSEC ultrastructure, and endocytosis receptor expression (also examined by qPCR and western blot). In both age groups, the Glmpgt/gt mice showed multifocal liver injury and fibrosis. The uptake of FITC-FSA in LSECs was significantly reduced in Glmpgt/gt compared to wild-type mice. Expression of LSEC receptors stabilin-1 (Stab1), and mannose receptor (Mcr1) was almost similar in liver of Glmpgt/gt mice and age-matched controls. At the same time, immunostaining revealed differences in the stabilin-1 expression pattern in sinusoids and accumulation of stabilin-1-positive macrophages in Glmpgt/gt liver. FcγRIIb (Fcgr2b), which mediates LSEC endocytosis of soluble immune complexes was widely and significantly downregulated in Glmpgt/gt liver. Despite increased collagen in space of Disse, LSECs of Glmpgt/gt mice showed well-preserved fenestrae organized in sieve plates but the frequency of holes >400 nm in diameter was increased, especially in areas with hepatocyte damage. In both genotypes, FITC-FSA also distributed to endothelial cells of spleen and bone marrow sinusoids, suggesting that these locations may function as possible compensatory sites of clearance of blood-borne scavenger receptor ligands in liver fibrosis.
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Affiliation(s)
- Milton Boaheng Antwi
- Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
- Section of Haematology, University Hospital of North Norway, Tromsø, Norway
| | - Gianina Dumitriu
- Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | | | | | - Ruomei Li
- Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Bård Smedsrød
- Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Anders Vik
- Section of Haematology, University Hospital of North Norway, Tromsø, Norway
- Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Winnie Eskild
- Department of Biosciences, University of Oslo, Oslo, Norway
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2
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Gu J, Geng M, Qi M, Wang L, Zhang Y, Gao J. The role of lysosomal membrane proteins in glucose and lipid metabolism. FASEB J 2021; 35:e21848. [PMID: 34582051 DOI: 10.1096/fj.202002602r] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/11/2021] [Accepted: 07/26/2021] [Indexed: 11/11/2022]
Abstract
Lysosomes have long been regarded as the "garbage dump" of the cell. More recently, however, researchers have revealed novel roles for lysosomal membranes in autophagy, ion transport, nutrition sensing, and membrane fusion and repair. With active research into lysosomal membrane proteins (LMP), increasing evidence has become available showing that LMPs are inextricably linked to glucose and lipid metabolism, and this relationship represents mutual influence and regulation. In this review, we summarize the roles of LMPs in relation to glucose and lipid metabolism, and describe their roles in glucose transport, glycolysis, cholesterol transport, and lipophagy. The role of transport proteins can be traced back to the original discoveries of GLUT8, NPC1, and NPC2, which were all found to have significant roles in the pathways involved in glucose and lipid metabolism. CLC-5 and SIDT2-knockout animals show serious phenotypic disorders of metabolism, and V-ATPase and LAMP-2 have been found to interact with proteins related to glucose and lipid metabolism. These findings all emphasize the critical role of LMPs in glycolipid metabolism and help to strengthen our understanding of the independent and close relationship between LMPs and glycolipid metabolism.
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Affiliation(s)
- Jing Gu
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
| | - Mengya Geng
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Mengxiang Qi
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Lizhuo Wang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Yao Zhang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Jialin Gao
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
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Milone R, Scalise R, Pasquariello R, Berloffa S, Ricca I, Battini R. De Novo 1q21.3q22 Duplication Revaluation in a "Cold" Complex Neuropsychiatric Case with Syndromic Intellectual Disability. Genes (Basel) 2021; 12:genes12040511. [PMID: 33807234 PMCID: PMC8066010 DOI: 10.3390/genes12040511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/24/2021] [Accepted: 03/28/2021] [Indexed: 11/26/2022] Open
Abstract
Syndromic intellectual disability often obtains a genetic diagnosis due to the combination of first and next generation sequencing techniques, although their interpretation may require revaluation over the years. Here we report on a composite neuropsychiatric case whose phenotype includes moderate intellectual disability, spastic paraparesis, movement disorder, and bipolar disorder, harboring a 1.802 Mb de novo 1q21.3q22 duplication. The role of this duplication has been reconsidered in the light of negativity of many other genetic exams, and of the possible pathogenic role of many genes included in this duplication, potentially configuring a contiguous gene-duplication syndrome.
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Affiliation(s)
- Roberta Milone
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, 56128 Pisa, Italy; (R.M.); (R.S.); (R.P.); (S.B.)
| | - Roberta Scalise
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, 56128 Pisa, Italy; (R.M.); (R.S.); (R.P.); (S.B.)
- Tuscan PhD Program of Neuroscience, University of Florence, Pisa and Siena, 50139 Florence, Italy
| | - Rosa Pasquariello
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, 56128 Pisa, Italy; (R.M.); (R.S.); (R.P.); (S.B.)
| | - Stefano Berloffa
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, 56128 Pisa, Italy; (R.M.); (R.S.); (R.P.); (S.B.)
| | - Ivana Ricca
- Molecular Medicine, IRCCS Stella Maris Foundation, 56128 Pisa, Italy;
| | - Roberta Battini
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Calambrone, 56128 Pisa, Italy; (R.M.); (R.S.); (R.P.); (S.B.)
- Department of Clinical and Experimental Medicine, University of Pisa, 56125 Pisa, Italy
- Correspondence: ; Tel.: +39-050886229; Fax: +39-050886247
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Kong XY, Feng YZ, Eftestøl E, Kase ET, Haugum H, Eskild W, Rustan AC, Thoresen GH. Increased glucose utilization and decreased fatty acid metabolism in myotubes from Glmp(gt/gt) mice. Arch Physiol Biochem 2016; 122:36-45. [PMID: 26707125 DOI: 10.3109/13813455.2015.1120752] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Glycosylated lysosomal membrane protein (GLMP) has been reported to enhance the expression from a peroxisome proliferator-activated receptor alpha (PPARα) responsive promoter, but also to be an integral lysosomal membrane protein. Using myotubes established from wild-type and Glmp(gt/gt) mice, the importance of GLMP in skeletal muscle was examined. Glmp(gt/gt) myotubes expressed a more glycolytic phenotype than wild-type myotubes. Myotubes from Glmp(gt/gt) mice metabolized glucose faster and had a larger pool of intracellular glycogen, while oleic acid uptake, storage and oxidation were significantly reduced. Gene expression analyses indicated lower expression of three PPAR-isoforms, a co-regulator of PPAR (PGC1α) and several genes important for lipid metabolism in Glmp(gt/gt) myotubes. However, ablation of GLMP did not seem to substantially impair the response to PPAR agonists. In conclusion, myotubes established from Glmp(gt/gt) mice were more glycolytic than myotubes from wild-type animals, in spite of no differences in muscle fiber types in vivo.
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Affiliation(s)
| | - Yuan Zeng Feng
- b Department of Pharmaceutical Biosciences , School of Pharmacy, University of Oslo , Oslo , Norway , and
| | | | - Eili T Kase
- b Department of Pharmaceutical Biosciences , School of Pharmacy, University of Oslo , Oslo , Norway , and
| | - Hanne Haugum
- b Department of Pharmaceutical Biosciences , School of Pharmacy, University of Oslo , Oslo , Norway , and
| | | | - Arild C Rustan
- b Department of Pharmaceutical Biosciences , School of Pharmacy, University of Oslo , Oslo , Norway , and
| | - G Hege Thoresen
- b Department of Pharmaceutical Biosciences , School of Pharmacy, University of Oslo , Oslo , Norway , and
- c Department of Pharmacology , Institute of Clinical Medicine, University of Oslo and Oslo University Hospital , Oslo , Norway
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Kong XY, Kase ET, Herskedal A, Schjalm C, Damme M, Nesset CK, Thoresen GH, Rustan AC, Eskild W. Lack of the Lysosomal Membrane Protein, GLMP, in Mice Results in Metabolic Dysregulation in Liver. PLoS One 2015; 10:e0129402. [PMID: 26047317 PMCID: PMC4457871 DOI: 10.1371/journal.pone.0129402] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/07/2015] [Indexed: 12/25/2022] Open
Abstract
Ablation of glycosylated lysosomal membrane protein (GLMP, formerly known as NCU-G1) has been shown to cause chronic liver injury which progresses into liver fibrosis in mice. Both lysosomal dysfunction and chronic liver injury can cause metabolic dysregulation. Glmpgt/gt mice (formerly known as Ncu-g1gt/gtmice) were studied between 3 weeks and 9 months of age. Body weight gain and feed efficiency of Glmpgt/gt mice were comparable to wild type siblings, only at the age of 9 months the Glmpgt/gt siblings had significantly reduced body weight. Reduced size of epididymal fat pads was accompanied by hepatosplenomegaly in Glmpgt/gt mice. Blood analysis revealed reduced levels of blood glucose, circulating triacylglycerol and non-esterified fatty acids in Glmpgt/gt mice. Increased flux of glucose, increased de novo lipogenesis and lipid accumulation were detected in Glmpgt/gt primary hepatocytes, as well as elevated triacylglycerol levels in Glmpgt/gt liver homogenates, compared to hepatocytes and liver from wild type mice. Gene expression analysis showed an increased expression of genes involved in fatty acid uptake and lipogenesis in Glmpgt/gt liver compared to wild type. Our findings are in agreement with the metabolic alterations observed in other mouse models lacking lysosomal proteins, and with alterations characteristic for advanced chronic liver injury.
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Affiliation(s)
- Xiang Yi Kong
- Department of Bioscience, University of Oslo, Oslo, Norway
| | - Eili Tranheim Kase
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | | | | | - Markus Damme
- Institute of Biochemistry, Christian-Albrechts-Universität Kiel, Kiel, Germany
| | | | - G. Hege Thoresen
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
- Department of Pharmacology, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Arild C. Rustan
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Winnie Eskild
- Department of Bioscience, University of Oslo, Oslo, Norway
- * E-mail:
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Kong XY, Nesset CK, Damme M, Løberg EM, Lübke T, Mæhlen J, Andersson KB, Lorenzo PI, Roos N, Thoresen GH, Rustan AC, Kase ET, Eskild W. Loss of lysosomal membrane protein NCU-G1 in mice results in spontaneous liver fibrosis with accumulation of lipofuscin and iron in Kupffer cells. Dis Model Mech 2014; 7:351-62. [PMID: 24487409 PMCID: PMC3944495 DOI: 10.1242/dmm.014050] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Human kidney predominant protein, NCU-G1, is a highly conserved protein with an unknown biological function. Initially described as a nuclear protein, it was later shown to be a bona fide lysosomal integral membrane protein. To gain insight into the physiological function of NCU-G1, mice with no detectable expression of this gene were created using a gene-trap strategy, and Ncu-g1gt/gt mice were successfully characterized. Lysosomal disorders are mainly caused by lack of or malfunctioning of proteins in the endosomal-lysosomal pathway. The clinical symptoms vary, but often include liver dysfunction. Persistent liver damage activates fibrogenesis and, if unremedied, eventually leads to liver fibrosis/cirrhosis and death. We demonstrate that the disruption of Ncu-g1 results in spontaneous liver fibrosis in mice as the predominant phenotype. Evidence for an increased rate of hepatic cell death, oxidative stress and active fibrogenesis were detected in Ncu-g1gt/gt liver. In addition to collagen deposition, microscopic examination of liver sections revealed accumulation of autofluorescent lipofuscin and iron in Ncu-g1gt/gt Kupffer cells. Because only a few transgenic mouse models have been identified with chronic liver injury and spontaneous liver fibrosis development, we propose that the Ncu-g1gt/gt mouse could be a valuable new tool in the development of novel treatments for the attenuation of fibrosis due to chronic liver damage.
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Affiliation(s)
- Xiang Y Kong
- Department of Bioscience, University of Oslo, 0316 Oslo, Norway
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Abstract
Until recently, a modest number of approx. 40 lysosomal membrane proteins had been identified and even fewer were characterized in their function. In a proteomic study, using lysosomal membranes from human placenta we identified several candidate lysosomal membrane proteins and proved the lysosomal localization of two of them. In the present study, we demonstrate the lysosomal localization of the mouse orthologue of the human C1orf85 protein, which has been termed kidney-predominant protein NCU-G1 (GenBank® accession number: AB027141). NCU-G1 encodes a 404 amino acid protein with a calculated molecular mass of 39 kDa. The bioinformatics analysis of its amino acid sequence suggests it is a type I transmembrane protein containing a single tyrosine-based consensus lysosomal sorting motif at position 400 within the 12-residue C-terminal tail. Its lysosomal localization was confirmed using immunofluorescence with a C-terminally His-tagged NCU-G1 and the lysosomal marker LAMP-1 (lysosome-associated membrane protein-1) as a reference, and by subcellular fractionation of mouse liver after a tyloxapol-induced density shift of the lysosomal fraction using an anti-NCU-G1 antiserum. In transiently transfected HT1080 and HeLa cells, the His-tagged NCU-G1 was detected in two molecular forms with apparent protein sizes of 70 and 80 kDa, and in mouse liver the endogenous wild-type NCU-G1 was detected as a 75 kDa protein. The remarkable difference between the apparent and the calculated molecular masses of NCU-G1 was shown, by digesting the protein with N-glycosidase F, to be due to an extensive glycosylation. The lysosomal localization was impaired by mutational replacement of an alanine residue for the tyrosine residue within the putative sorting motif.
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