The role and mechanism of action of endoplasmic reticulum transmembrane protein 166 in liver lipid metabolism
Objective To investigate the role and specific molecular mechanism of action of endoplasmic reticulum transmembrane protein 166 (TMEM166) in liver lipid metabolism. Methods Tmem166flox/flox mice were crossed with Alb-Cre mice, and the offspring Tmem166+/+ mice were selected as group A, while the Tme...
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| Format: | Article |
| Language: | zho |
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Editorial Office of Journal of Precision Medicine
2025-08-01
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| Series: | 精准医学杂志 |
| Subjects: | |
| Online Access: | https://jpmed.qdu.edu.cn/fileup/2096-529X/PDF/1754471504551-202308586.pdf |
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| Summary: | Objective To investigate the role and specific molecular mechanism of action of endoplasmic reticulum transmembrane protein 166 (TMEM166) in liver lipid metabolism. Methods Tmem166flox/flox mice were crossed with Alb-Cre mice, and the offspring Tmem166+/+ mice were selected as group A, while the Tmem166-/- mice were selected as group B, with 8 mice in each group. The mice were fed till 24 weeks of age, and serum and liver tissue samples were isolated. HepG2 cells were divided into group C (transfected with sh-vector), group D (transfected with sh-TMEM166), group E (transfected with sh-vector and treated with oleic acid [OA]), group F (transfected with sh-TMEM166 and treated with OA), group G (co-transfected with sh-TMEM166 and siNC and treated with OA), and group H (co-transfected with sh-TMEM166 and siCD36 and treated with OA). Western blotting was used to measure the protein expression level of TMEM166 in liver tissue of the mice in groups A and B and in cells in groups C-F; quantitative real-time PCR and Western blotting were used to measure the expression levels of CD36, FATPs, and other fatty acid uptake-related factors in cells and liver tissue; HE staining was used to observe the pathological changes of liver tissue in groups A and B, and oil red O staining was used to observe the accumulation of lipid droplets in liver tissue of groups A and B and in cells of groups E-H; corresponding kits were used to measure the serum levels of triglyceride (TG), total cholesterol (TC), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and non-esterified fatty acids (NEFA) in the mice in groups A and B, as well as the contents of TG and NEFA in the mice in groups A and B and in the cells in groups C-H. Results Animal experiments showed that compared with group A, group B had a significant reduction in the relative protein expression level of TMEM166 in liver tissue (t=6.55,P<0.01), significant increases in liver vacuolization and lipid droplets, and significant increases in the serum levels of TG, ALT, and AST and the levels of TG and NEFA in liver tissue (t=3.10-28.53,P<0.05), as well as significant increases in the mRNA and protein expression levels of CD36 and FATPs in liver tissue (t=4.48-52.27,P<0.05). Cell experiments showed that TMEM166 knockdown and OA treatment had significant influence on the levels of TG and NEFA, the protein expression level of TMEM166, and the mRNA and protein expression levels of CD36, FATPs in each group of cells (FTMEM166 knockdown=23.95-185.00,FOA treatment=26.99-991.80,P<0.01), with an interaction between TMEM166 knockdown and OA treatment on the level of TG and the mRNA expression level of PPARγ2 in cells (Finteraction=9.01,15.50,P<0.05), and the individual effect analysis showed that TMEM166 knockdown or OA treatment alone could cause the significant increases in all the above indicators (F=21.89-393.90,P<0.05). Oil red O staining showed that group F had a significant increase in the accumulation of lipid droplets than group E, and compared with group G, group H had significant reductions in the protein expression level of CD36 and the levels of TG and NEFA (t=7.03-12.07,P<0.01), as well as a significant reduction in the accumulation of lipid droplets. Conclusion Downregulation of TMEM166 can increase the expression of CD36 and promote fatty acid uptake and lipid droplet accumulation in liver cells, thereby affecting the lipid homeostasis in the liver, and the regulatory mechanism of TMEM166 on CD36 may be associated with the activation of PPARγ2. |
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| ISSN: | 2096-529X |