Hong-mei Gu1, Faqi Wang1, Adekunle Alabi1, Shijun Deng1, Shucun Qin1, Da-wei Zhang2. 1. From the Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Alberta, Canada (H.-M.G., F.W., A.A., S.D., D.-W.Z.); and Institute of Atherosclerosis in Taishan Medical University, Taian, China (S.Q., D.-W.Z.). 2. From the Departments of Pediatrics and Biochemistry, Group on the Molecular and Cell Biology of Lipids, University of Alberta, Alberta, Canada (H.-M.G., F.W., A.A., S.D., D.-W.Z.); and Institute of Atherosclerosis in Taishan Medical University, Taian, China (S.Q., D.-W.Z.). dzhang@ualberta.ca.
Abstract
OBJECTIVE: ATP-binding cassette transporter G1 (ABCG1) mediates cholesterol efflux to lipidated lipoproteins. Conflicting data about cellular localization of ABCG1 and its effect on cholesterol efflux have been reported. Here, we investigated the underlying mechanisms for these different observations. APPROACH AND RESULTS: Confocal microscopy and biotinylation were used to assess cell surface localization of ABCG1. We found that mouse ABCG1 (mABCG1) used in one previous study has a substitution of Leu to Pro at position 550 (mG1-L550P). When the corresponding Leu at position 562 in human ABCG1 (hABCG1) was mutated to Pro (hG1-L562P), the mutant hABCG1, like mG1-L550P, mainly resided intracellularly, whereas wild-type mABCG1 and hABCG1 were localized on the plasma membrane. However, replacement of this Leu with Pro had no significant effect on mABCG1- and hABCG1-mediated cholesterol efflux. CONCLUSIONS: Leu at position 550/562 in mABCG1/hABCG1 is critical for their plasma membrane localization but not for ABCG1-mediated cholesterol efflux. Our findings indicate that the substitution of Leu to Pro at position 550 in mABCG1 may contribute to the non-cell surface localization of mABCG1 observed in the previous study.
OBJECTIVE:ATP-binding cassette transporter G1 (ABCG1) mediates cholesterol efflux to lipidated lipoproteins. Conflicting data about cellular localization of ABCG1 and its effect on cholesterol efflux have been reported. Here, we investigated the underlying mechanisms for these different observations. APPROACH AND RESULTS: Confocal microscopy and biotinylation were used to assess cell surface localization of ABCG1. We found that mouseABCG1 (mABCG1) used in one previous study has a substitution of Leu to Pro at position 550 (mG1-L550P). When the corresponding Leu at position 562 in humanABCG1 (hABCG1) was mutated to Pro (hG1-L562P), the mutant hABCG1, like mG1-L550P, mainly resided intracellularly, whereas wild-type mABCG1 and hABCG1 were localized on the plasma membrane. However, replacement of this Leu with Pro had no significant effect on mABCG1- and hABCG1-mediated cholesterol efflux. CONCLUSIONS:Leu at position 550/562 in mABCG1/hABCG1 is critical for their plasma membrane localization but not for ABCG1-mediated cholesterol efflux. Our findings indicate that the substitution of Leu to Pro at position 550 in mABCG1 may contribute to the non-cell surface localization of mABCG1 observed in the previous study.
Authors: Hong S Lu; Ann Marie Schmidt; Robert A Hegele; Nigel Mackman; Daniel J Rader; Christian Weber; Alan Daugherty Journal: Arterioscler Thromb Vasc Biol Date: 2018-10 Impact factor: 8.311