Posttranscriptional Regulation of the Human LDL Receptor by the U2-Spliceosome. Issue 1 (7th January 2022)

• Record Type: Journal Article
• Authors: Zanoni, Paolo; Panteloglou, Grigorios; Othman, Alaa; Haas, Joel T.; Meier, Roger; Rimbert, Antoine; Futema, Marta; Abou Khalil, Yara; Norrelykke, Simon F.; Rzepiela, Andrzej J.; Stoma, Szymon; Stebler, Michael; van Dijk, Freerk; Wijers, Melinde; Wolters, Justina C.; Dalila, Nawar; Huijkman, Nicolette C. A.; Smit, Marieke; Gallo, Antonio; Carreau, Valérie; Philippi, Anne; Rabès, Jean-Pierre; Boileau, Catherine; Visentin, Michele; Vonghia, Luisa; Weyler, Jonas; Francque, Sven; Verrijken, An; Verhaegen, Ann; Van Gaal, Luc; van der Graaf, Adriaan; van Rosmalen, Belle V.; Robert, Jerome; Velagapudi, Srividya; Yalcinkaya, Mustafa; Keel, Michaela; Radosavljevic, Silvija; Geier, Andreas; Tybjaerg-Hansen, Anne; Varret, Mathilde; Rohrer, Lucia; Humphries, Steve E.; Staels, Bart; van de Sluis, Bart; Kuivenhoven, Jan Albert; von Eckardstein, Arnold;
• Is Part Of: Circulation research. Volume 130:Issue 1(2022)
• Publication Date: 2022-01-07
• Subjects: hepatocytes -- cardiovascular diseases -- endocytosis -- hypercholesterolemia -- spliceosomes; Cardiovascular system -- Periodicals; Blood -- Circulation -- Periodicals; Blood Circulation; Cardiovascular System; Vascular Diseases; Sang -- Circulation -- Périodiques; Appareil cardiovasculaire -- Périodiques; 612.1
• DOI: 10.1161/CIRCRESAHA.120.318141
• Languages: English
• ISSNs: 0009-7330

Abstract

Abstract : Background: The LDLR (low-density lipoprotein receptor) in the liver is the major determinant of LDL-cholesterol levels in human plasma. The discovery of genes that regulate the activity of LDLR helps to identify pathomechanisms of hypercholesterolemia and novel therapeutic targets against atherosclerotic cardiovascular disease. Methods: We performed a genome-wide RNA interference screen for genes limiting the uptake of fluorescent LDL into Huh-7 hepatocarcinoma cells. Top hit genes were validated by in vitro experiments as well as analyses of data sets on gene expression and variants in human populations. Results: The knockdown of 54 genes significantly inhibited LDL uptake. Fifteen of them encode for components or interactors of the U2-spliceosome. Knocking down any one of 11 out of 15 genes resulted in the selective retention of intron 3 of LDLR . The translated LDLR fragment lacks 88% of the full length LDLR and is detectable neither in nontransfected cells nor in human plasma. The hepatic expression of the intron 3 retention transcript is increased in nonalcoholic fatty liver disease as well as after bariatric surgery. Its expression in blood cells correlates with LDL-cholesterol and age. Single nucleotide polymorphisms and 3 rare variants of one spliceosome gene, RBM25, are associated with LDL-cholesterol in the population and familial hypercholesterolemia, respectively. Compared with overexpression of wild-type RBM25, overexpression of the 3 rare RBM25 mutants in Huh-7 cells led to lower LDL uptake. Conclusions: We identified a novel mechanism of posttranscriptional regulation of LDLR activity in humans and associations of genetic variants of RBM25 with LDL-cholesterol levels. Abstract : Supplemental Digital Content is available in the text.