Helical apolipoproteins of high-density lipoprotein enhance phagocytosis by stabilizing ATP-binding cassette transporter A7

Tanaka, Norihiro; Abe-Dohmae, Sumiko; Iwamoto, Noriyuki; Fitzgerald, Michael L.; Yokoyama, Shinji

doi:10.1194/jlr.m006049

Cited by 59 publications

(70 citation statements)

References 42 publications

(47 reference statements)

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“…This probably explains why we observed that calpain-mediated proteolysis contributed only modestly to ABCA1 degradation in our studies, because they were performed in media containing 0.5% serum. Calpain-mediated degradation of plasma membrane localized ABCG1 and ABCA7 have also been reported (25,54), although in our studies we observed no obvious calpain-dependent degradation of ABCG1. However, only 10 -20% of cellular ABCG1 is expressed at the plasma membrane, 4 and more targeted studies may be needed to detect changes in turnover of this minor proportion of ABCG1 protein.…”

Section: Discussioncontrasting

confidence: 54%

Cellular Cholesterol Regulates Ubiquitination and Degradation of the Cholesterol Export Proteins ABCA1 and ABCG1

Hsieh

Kim

Gelissen

et al. 2014

Journal of Biological Chemistry

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Background: Cholesterol transporters ABCA1 and ABCG1 export excess cellular cholesterol and protect against atherosclerosis. Results: Cholesterol loading decreases cellular degradation of ABCA1 and ABCG1 and also their ubiquitination. Conclusion: Cholesterol-dependent suppression of ABCA1 and ABCG1 ubiquitination decreases their proteasomal degradation. Significance: This mechanism enhances the capacity of cholesterol-loaded cells to export their excess cholesterol.

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Section: Discussioncontrasting

confidence: 54%

Cellular Cholesterol Regulates Ubiquitination and Degradation of the Cholesterol Export Proteins ABCA1 and ABCG1

Hsieh

Kim

Gelissen

et al. 2014

Journal of Biological Chemistry

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“…Our previous study with immunofluorescent probing indicated intracellular localization of endogemous ABCA7 15) , however, estimation of cell surface ABCA7 in J774 and mouse fibroblasts by a biotinylation technique directly demonstrated that endogenous ABCA7 mainly existed in the plasma membrane and apoA-increased cell surface ABCA7 (Fig. 1A) 43) . This discrepancy may be consistent with the assumption that ABCA7 turns over rapidly on the cell surface.…”

Section: Subcellular Localization Of Abca7mentioning

confidence: 86%

“…The results indicated that ABCA7 contains N-glycoside-linked oligosaccharides as ABCA1 (Fig. 1B) 43) . This modification of ABCA7 was not influenced by extracellular apoA- 43) .…”

Section: Glycosylation Of Abca7mentioning

confidence: 89%

“…Our recent study showed that endogenous ABCA7 was also stabilized against its calpainmediated degradation by helical apolipoproteins (Fig. 1C) 43) . Thus, both ABCA7 and ABCA1 seem to be processed essentially in a similar manner.…”

Section: Turnover and Degradation Of Abca7mentioning

confidence: 89%

“…Effects of helical apolipoproteins on the stabilization of ABCA7 and enhancement of phageocytosis were examined 43) . Decay of ABCA7 protein examined in the presence of the protein synthesis inhibitor cycloheximide was retarded by apoA-and apoA-, similarly to the findings with ABCA1 (Fig.…”

Section: Helical Apolipoprotein-mediated Stabilization Of Abca7 and Pmentioning

confidence: 99%

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Roles of ATP-Binding Cassette Transporter A7 in Cholesterol Homeostasis and Host Defense System

Tanaka

Abe-Dohmae

Iwamoto

et al. 2011

JAT

Self Cite

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ATP-binding cassette transporter (ABC) A7 is an ABC family protein that is a so-called full-size ABC transporter, highly homologous to ABCA1, which mediates the biogenesis of high-density lipoprotein (HDL) with cellular lipid and helical apolipoproteins. ABCA7 mediates the formation of HDL when exogenously transfected and expressed; however, endogenous ABCA7 was shown to have no significant impact on the generation of HDL and was found to be associated with phagocytosis regulated by sterol regulatory element binding protein 2. Since phagocytosis is one of the fundamental functions of animal cells as an important responsive reaction to infection, injury and apoptosis, ABCA7 seems to be one of the key molecules linking sterol homeostasis and the host defense system. In this context, HDL apolipoproteins were shown to enhance phagocytosis by stabilizing ABCA7 against calpain-mediated degradation and increasing its activity, shedding light on a new aspect of the regulation of the host-defense system. Roles of ATP-Binding Cassette Transporter (ABC) A7 in cholesterol homeostasisHigh-density lipoprotein (HDL) apolipoproteins, such as apolipoprotein (apo) A-and apoA-, are helical amphiphilic proteins bound to the HDL lipid surface in equilibrium with an aqueous phase. These helical apolipoproteins interact with the cell surface in their free form and generate HDL particles by removing cellular phospholipid and cholesterol [1][2][3] . Fibroblasts from patients with Tangier disease, a genetic HDL deficiency, lack the interaction with apolipoprotein 4, 5) due to mutations in ABCA1 [6][7][8] , indicating that this reaction is the main source of plasma HDL. The reaction is one of the major pathways of cellular cholesterol release along with diffusion-mediated nonspecific efflux 9) . Thus, ABCA1 is a key membrane protein for cholesterol homeostasis, for the generation of HDL and the release of cell cholesterol for its catabolism 10) . ABCA1 is one of the ABC family proteins consisting of two sets of multiple membranespanning domains plus the Walker motifs for ATP interaction 11, 12) , and is thereby classified as a so-called full-size ABC transporter.Human ABCA7 is another full-size ABC transporter showing the highest homology among those known to human ABCA1 (54%) and human ABCA4 (49%) 13) . On the other hand, its interspecies identity of the protein sequences is 79% between humans and mice, less than that of ABCA1 (95%) and ABCA4 (88%) 14)

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High‐Density Lipoproteins

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Helical apolipoproteins of high-density lipoprotein enhance phagocytosis by stabilizing ATP-binding cassette transporter A7

Cited by 59 publications

References 42 publications

Cellular Cholesterol Regulates Ubiquitination and Degradation of the Cholesterol Export Proteins ABCA1 and ABCG1

Cellular Cholesterol Regulates Ubiquitination and Degradation of the Cholesterol Export Proteins ABCA1 and ABCG1

Roles of ATP-Binding Cassette Transporter A7 in Cholesterol Homeostasis and Host Defense System

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