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The East Asian-specific LPL p.Ala288Thr (c.862G > A) missense variant exerts a mild effect on protein function
BACKGROUND: Lipoprotein lipase (LPL) is the key enzyme responsible for the hydrolysis of triglycerides. Loss-of-function variants in the LPL gene are associated with hypertriglyceridemia (HTG) and HTG-related diseases. Unlike nonsense, frameshift and canonical GT-AG splice site variants, a pathogeni...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10405562/ https://www.ncbi.nlm.nih.gov/pubmed/37550668 http://dx.doi.org/10.1186/s12944-023-01875-3 |
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author | Hu, Yuepeng Zhang, Guofu Yang, Qi Pu, Na Li, Kaiwei Li, Baiqiang Cooper, David N. Tong, Zhihui Li, Weiqin Chen, Jian-Min |
author_facet | Hu, Yuepeng Zhang, Guofu Yang, Qi Pu, Na Li, Kaiwei Li, Baiqiang Cooper, David N. Tong, Zhihui Li, Weiqin Chen, Jian-Min |
author_sort | Hu, Yuepeng |
collection | PubMed |
description | BACKGROUND: Lipoprotein lipase (LPL) is the key enzyme responsible for the hydrolysis of triglycerides. Loss-of-function variants in the LPL gene are associated with hypertriglyceridemia (HTG) and HTG-related diseases. Unlike nonsense, frameshift and canonical GT-AG splice site variants, a pathogenic role for clinically identified LPL missense variants should generally be confirmed by functional analysis. Herein, we describe the clinical and functional analysis of a rare LPL missense variant. METHODS: Chinese patients with HTG-associated acute pancreatitis (HTG-AP) were screened for rare nonsense, frameshift, missense or canonical GT-AG splice site variants in LPL and four other lipid metabolism-related genes (APOC2, APOA5, GPIHBP1 and LMF1) by Sanger sequencing. The functional consequences of the LPL missense variant of interest were characterized by in vitro expression in HEK-293T and COS-7 cells followed by Western blot and LPL activity assays. RESULTS: Five unrelated HTG-AP patients were found to be heterozygous for a rare East Asian-specific LPL missense variant, c.862G > A (p.Ala288Thr). All five patients were adult males, and all were overweight and had a long history of alcohol consumption. Transfection of LPL wild-type and c.862G > A expression vectors into two cell lines followed by Western blot analysis served to exclude the possibility that the p.Ala288Thr missense variant either impaired protein synthesis or increased protein degradation. Contrary to a previous functional study that claimed that p.Ala288Thr had a severe impact on LPL function (reportedly having 36% normal activity), our experiments consistently demonstrated that the variant had a comparatively mild effect on LPL functional activity, which was mediated through its impact upon LPL protein secretion (~ 20% reduced secretion compared to wild-type). CONCLUSIONS: In this study, we identified the East Asian-specific LPL c.862G > A (p.Ala288Thr) missense variant in five unrelated HTG-AP patients. We demonstrated that this variant exerted only a relatively mild effect on LPL function in two cell lines. Heterozygosity for this LPL variant may have combined with alcohol consumption to trigger HTG-AP in these patients. |
format | Online Article Text |
id | pubmed-10405562 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-104055622023-08-08 The East Asian-specific LPL p.Ala288Thr (c.862G > A) missense variant exerts a mild effect on protein function Hu, Yuepeng Zhang, Guofu Yang, Qi Pu, Na Li, Kaiwei Li, Baiqiang Cooper, David N. Tong, Zhihui Li, Weiqin Chen, Jian-Min Lipids Health Dis Research BACKGROUND: Lipoprotein lipase (LPL) is the key enzyme responsible for the hydrolysis of triglycerides. Loss-of-function variants in the LPL gene are associated with hypertriglyceridemia (HTG) and HTG-related diseases. Unlike nonsense, frameshift and canonical GT-AG splice site variants, a pathogenic role for clinically identified LPL missense variants should generally be confirmed by functional analysis. Herein, we describe the clinical and functional analysis of a rare LPL missense variant. METHODS: Chinese patients with HTG-associated acute pancreatitis (HTG-AP) were screened for rare nonsense, frameshift, missense or canonical GT-AG splice site variants in LPL and four other lipid metabolism-related genes (APOC2, APOA5, GPIHBP1 and LMF1) by Sanger sequencing. The functional consequences of the LPL missense variant of interest were characterized by in vitro expression in HEK-293T and COS-7 cells followed by Western blot and LPL activity assays. RESULTS: Five unrelated HTG-AP patients were found to be heterozygous for a rare East Asian-specific LPL missense variant, c.862G > A (p.Ala288Thr). All five patients were adult males, and all were overweight and had a long history of alcohol consumption. Transfection of LPL wild-type and c.862G > A expression vectors into two cell lines followed by Western blot analysis served to exclude the possibility that the p.Ala288Thr missense variant either impaired protein synthesis or increased protein degradation. Contrary to a previous functional study that claimed that p.Ala288Thr had a severe impact on LPL function (reportedly having 36% normal activity), our experiments consistently demonstrated that the variant had a comparatively mild effect on LPL functional activity, which was mediated through its impact upon LPL protein secretion (~ 20% reduced secretion compared to wild-type). CONCLUSIONS: In this study, we identified the East Asian-specific LPL c.862G > A (p.Ala288Thr) missense variant in five unrelated HTG-AP patients. We demonstrated that this variant exerted only a relatively mild effect on LPL function in two cell lines. Heterozygosity for this LPL variant may have combined with alcohol consumption to trigger HTG-AP in these patients. BioMed Central 2023-08-07 /pmc/articles/PMC10405562/ /pubmed/37550668 http://dx.doi.org/10.1186/s12944-023-01875-3 Text en © The Author(s) 2023 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data. |
spellingShingle | Research Hu, Yuepeng Zhang, Guofu Yang, Qi Pu, Na Li, Kaiwei Li, Baiqiang Cooper, David N. Tong, Zhihui Li, Weiqin Chen, Jian-Min The East Asian-specific LPL p.Ala288Thr (c.862G > A) missense variant exerts a mild effect on protein function |
title | The East Asian-specific LPL p.Ala288Thr (c.862G > A) missense variant exerts a mild effect on protein function |
title_full | The East Asian-specific LPL p.Ala288Thr (c.862G > A) missense variant exerts a mild effect on protein function |
title_fullStr | The East Asian-specific LPL p.Ala288Thr (c.862G > A) missense variant exerts a mild effect on protein function |
title_full_unstemmed | The East Asian-specific LPL p.Ala288Thr (c.862G > A) missense variant exerts a mild effect on protein function |
title_short | The East Asian-specific LPL p.Ala288Thr (c.862G > A) missense variant exerts a mild effect on protein function |
title_sort | east asian-specific lpl p.ala288thr (c.862g > a) missense variant exerts a mild effect on protein function |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10405562/ https://www.ncbi.nlm.nih.gov/pubmed/37550668 http://dx.doi.org/10.1186/s12944-023-01875-3 |
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