HDL apoA-1-mediated cholesterol efflux pathway requires multiple cellular proteins and signal transduction processes, including adenylyl cyclase (AC)/cAMP signaling. Due to the existence of multiple transmembrane AC isoforms, it was not known how many AC isoforms are expressed and which ones are essential for cholesterol efflux in macrophage foam cells. These questions were investigated in THP-1 macrophages in this study. Quantitative RT-PCR detected mRNAs for all nine transmembrane AC isoforms, but only the mRNA and protein of the AC1 isoform were consistently upregulated by cholesterol loading and apoA-1. AC1 shRNA interference decreased AC1 mRNA and protein levels, resulting in reduction of apoA-1-mediated cAMP production and cholesterol efflux, while the intracellular cholesterol levels remained high. Confocal microscopy showed that apoA-1 promoted translocation of cholesterol and formation of cholesterol-apoA-1 complexes (protrusions) on the cholesterol-loaded macrophage surface. AC1 shRNA-interfered macrophages showed no translocation of cholesterol to the cell surface. AC1 shRNA interference also disrupted cellular localization of the intracellular cholesterol indicator protein adipophillin, and the expression as well as surface translocation of ABCA1. Together, our results show that AC1 is a major isoform for apoA-1-activated cAMP signaling to promote cholesterol transport and exocytosis to the surface of THP-1 macrophage foam cells.
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http://dx.doi.org/10.1194/jlr.M082297 | DOI Listing |
Stem Cell Reports
December 2024
Department of Cardio Metabolic Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany. Electronic address:
Complement factor H (CFH) common genetic variants have been associated with age-related macular degeneration (AMD). While most previous in vitro RPE studies focused on the common p.His402Tyr CFH variant, we characterized rare CFH variants that are highly penetrant for AMD using induced pluripotent stem-cell-derived retinal pigment epithelium (iPSC-RPE).
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Shenzhen Bay Laboratory, Shenzhen, Guandong, China.
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Ronald M. Loeb Center for Alzheimer's Disease, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
Background: While compelling evidence highlights the importance of myeloid cells in the etiology of Alzheimer's Disease (AD), the relevance of immunometabolism still requires further exploration. Our analysis integrating AD genetics and myeloid cell genomics shows that lower levels of LACTB expression in myeloid cells is protective against AD, a finding supported by proteomics studies. As a mitochondrial active-site serine protein, LACTB has implications for mitochondrial morphology and bioenergetics.
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December 2024
Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA.
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National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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