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2 results on '"selective lipid transport"'

1. Multiple interactions between insect lipoproteins and fat body cells: extracellular trapping and endocytic trafficking

Author

Nico P. Dantuma, Marian A.P. Pijnenburg, Jacques H.B. Diederen, and Dick J. Van der Horst

Subjects
selective lipid transport, receptor-mediated endocytosis, lipophorin, locust, DiI, ultrasmall gold, Biochemistry, QD415-436
Abstract

The binding and internalization of a circulating insect lipoprotein, high density lipophorin (HDLp), by insect fat body cells was studied at the electron-microscopic level using ultrasmall gold-labeled HDLp and DiI-labeled HDLp, which were visualized by silver enhancement and diaminobenzidine photoconversion, respectively. Internalization of HDLp seems to conflict with the selective process by which the lipids are transported between HDLp and fat body cells. The pathway followed by the internalized lipoproteins was investigated. In addition, the localizations of HDLp in fat body cells of young and older adult locusts were compared because of the previously reported agerelated differences in distribution of cell-associated and internalized HDLp. In the present study, internalized labeled HDLp was observed in early endosomes, late endosomes, and putative lysosomes. In older adults, these labeled structures were much less abundant than in young adults. Moreover, in these animals, the labeled endosomal/lysosomal vesicles were located close to the plasma membranes. A more intense labeling was observed in the extracellular matrix in older adults compared to young adults. In both developmental stages, an apparent accumulation of labeled HDLp was found in extracellular spaces. We propose that this entrapment of HDLp may be essential for selective lipid transport between HDLp and fat body cells.—Dantuma, N. P., M. A. P. Pijnenburg, J. H. B. Diederen, and D. J. Van der Horst. Multiple interactions between insect lipoproteins and fat body cells: extracellular trapping and endocytic trafficking.

Published
1998
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2. The adaptor protein GIPC1 stabilizes the scavenger receptor SR-B1 and increases its cholesterol uptake

Author

Rui Liu, Salman Azhar, Yan-Fu Qu, Qian Zhou, Ziyu Zhang, Zhigang Hu, Li Liu, Wen-Jun Shen, and Zhigang Guo

Subjects
CD36 Antigens, Male, 0301 basic medicine, HFD, high-fat diet, Very low-density lipoprotein, IGF1R, insulin-like growth factor-1 receptor, SIK1, salt inducible kinase 1, ERα, estrogen receptors α, BMI, body mass index, LH, luteinizing hormone, Mice, Obese, PFU, plaque-forming units, Biochemistry, SR-B1, LXRβ, liver X receptors β, chemistry.chemical_compound, PDZ protein GIPC1, SF-1, steroidogenic factor 1, Post-translational regulation, Receptor, Ad-sh, adenoviruses with GIPC1 shRNA, Protein Stability, Chemistry, Cell biology, Cholesterol, Liver, ERβ, estrogen receptors β, LXRα, liver X receptors α, CREB, cAMP response element binding protein, ACTH, adrenocorticotropic hormone, Ad-GFP, adenovirus-expressing green fluorescent proteins, Dil, 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate, SR-B1, scavenger receptor class B type 1, Research Article, NRP1, neuropilin 1, cholesterol uptake, HDL, high-density lipoprotein, SREBP-1a, sterol-regulatory element binding protein-1a, GH1, GIPC homology 1, TG, Triglyceride, CEs, cholesteryl esters, 03 medical and health sciences, CHX, cycloheximide, selective lipid transport, Animals, Humans, TGFβR3, transforming growth factorβ receptor type Ⅲ, oxLDL, oxidized LDL, Scavenger receptor, Molecular Biology, Leu, leupeptin hemisulfate, Adaptor Proteins, Signal Transducing, Insulin-like growth factor 1 receptor, PPARα, peroxisome proliferator–activated receptor α, NR0B1 (DAX-1), nuclear receptor subfamily 0 group B member 1, 030102 biochemistry & molecular biology, HDL-C, HDL-cholesterol, Liver receptor homolog-1, FA, fatty acid, VLDL, very-low-density lipoprotein, Biological Transport, LDL-C, LDL-cholesterol, Cell Biology, Mice, Inbred C57BL, TC, total cholesterol, protein–protein interaction, 030104 developmental biology, MS, mass spectrometry, LRH-1, liver receptor homolog 1, FSH, follicle-stimulating hormone, adaptor protein, Lipoprotein
Abstract

The scavenger receptor class B type 1 (SR-B1), a high-density lipoprotein (HDL) receptor, is a membrane glycoprotein that mediates selective uptake of HDL-cholesterol and cholesterol ester (CE) into cells. SR-B1 is subject to posttranslational regulation; however, the underlying mechanisms still remain obscure. Here, we identified a novel SR-B1-interacting protein, GIPC1 (GAIP-interacting protein, C terminus 1) that interacts with SR-B1 and stabilizes SR-B1 by negative regulation of its proteasomal and lysosomal degradation pathways. The physiological interaction between SR-B1 and GIPC1 was supported by co-immunoprecipitation of wild-type and mutant GIPC1 constructs in SR-B1 ± GIPC1 overexpressing cells, in native liver cells, and in mouse liver tissues. Overexpression of GIPC1 increased endogenous SR-B1 protein levels, subsequently increasing selective HDL-cholesterol/CE uptake and cellular triglyceride (TG) and total cholesterol (TC) levels, whereas silencing of GIPC1 in the mouse liver was associated with blunted hepatic SR-B1 levels, elevated plasma TG and TC, and attenuated hepatic TG and TC content. A positive correlation was identified between GIPC1 and SR-B1 expression, and both expressions of GIPC1 and SR-B1 from human liver samples were inversely correlated with body mass index (BMI) from human subjects. We therefore conclude that GIPC1 plays a key role in the stability and function of SR-B1 and can also effectively regulate hepatic lipid and cholesterol metabolism. These findings expand our knowledge of the regulatory roles of GIPC1 and suggest that GIPC1 exerts a major effect on cell surface receptors such as SR-B1 and its associated hepatic lipid and cholesterol metabolic processes.

Published
2021
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