Identification and characterization of ABCA1-interactive proteins and their relevance to atherosclerosis

摘要: The ATP-binding cassette transporter 1 (ABCA1) has recently been identified as a major regulator of systemic HDL. main focus this work was to identify and further characterize ABCA1-interactive proteins. A Yeast-Two-Hybrid screening with the last 144 amino acids ABCA1 C-terminus bait performed. Our results indicate that forms heteromeric complex each of: Fas-associated death domain (FADD), beta2-syntrophin, syntaxin 13 flotillin-1, indicating role for beyond mere reverse cholesterol transport. interactions putative ABCA1-associated proteins were confirmed by independent approaches. In addition, functional studies performed elucidate physiological consequences these protein complexes. The finding FADD directly interacts is surprising links cellular HDL metabolism mainly described in context receptor-induced apoptosis, since plays well-established transduction apoptotic signals other processes. FADD/ABCA1 interaction may an anti-apoptotic function from suggested phosphatidylserine translocase activity. The C-terminal sequence previously binding motif PDZ domains syntrophin. We showed binds acts general adaptor membrane actin cytoskeleton via utrophin, highly homologous dystrophin. The cystic fibrosis transmembrane conductance (CFTR), member ABC family, reported interact 1A. Thereupon, we investigated syntaxins direct ABCA1-interactor family. Syntaxin 13, through its interacting pallidin (syntaxin protein), linked Hermansky-Pudlak syndrome (HPS) Chediak-Higachi (CHS). These lysosomal storage diseases are associated pulmonary prolonged bleeding caused defects Adapter protein-3 (AP-3). Recent publications show mutations Tangier patients related impaired platelet activation due presence ABCA1, 13-interacting AP-3 pathway. Moreover, deficiency leads enhanced phagocytosis macrophages fibroblasts, disturbances pathway. uptake apoA-I endocytic phagocytic ingestion also explain increased catabolism patients. causes degradation therefore be important maturation vesicular This potential both phagosomal compartment involved ABCA1-dependent choline-phospholipid efflux. integral flotillin-1 found ABCA1. Overexpression enhances filipodia formation, linking migration cytoskeletal changes. In second part human monocyte-derived loaded differently modified atherogenic LDLs, subsequently deloaded HDL3 order ascertain differential gene regulation within lipid-related pathways. characterization Affymetrix U133a chips. Ox-LDL induces less cytoplasmic cholesteryl ester accumulation than E-LDL, result chemical alterations during oxidation. efflux influences expression substantial portion structural elements large small ribosomal subunits. Deloading but not Ox-LDL, led distinguished upregulation genes polymerase-II complex, close relationship between taken up outside clathrin coated pits phagocytosis, control mechanisms at transcriptional level. E-LDL specific effect continues more downstream translation machinery represented 40S 60S well proteasomal where unneeded promptly degraded. In ATP synthases upregulated HDL3-induced deloading macrophages. LDL-receptor mediated downregulates intracellular synthesis inhibition HMGCoA reductase feedback mechanism. sensitive regulatory system subsequent whereas trapped inside cell. Thus, certain modification types lipoproteins indirectly machinery.