1
|
Mutation in Smek2 regulating hepatic glucose metabolism causes hypersarcosinemia and hyperhomocysteinemia in rats. Sci Rep 2023; 13:3053. [PMID: 36810603 PMCID: PMC9944932 DOI: 10.1038/s41598-022-26115-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 12/09/2022] [Indexed: 02/24/2023] Open
Abstract
Suppressor of mek1 (Dictyostelium) homolog 2 (Smek2), was identified as one of the responsible genes for diet-induced hypercholesterolemia (DIHC) of exogenously hypercholesterolemic (ExHC) rats. A deletion mutation in Smek2 leads to DIHC via impaired glycolysis in the livers of ExHC rats. The intracellular role of Smek2 remains obscure. We used microarrays to investigate Smek2 functions with ExHC and ExHC.BN-Dihc2BN congenic rats that harbor a non-pathological Smek2 allele from Brown-Norway rats on an ExHC background. Microarray analysis revealed that Smek2 dysfunction leads to extremely low sarcosine dehydrogenase (Sardh) expression in the liver of ExHC rats. Sarcosine dehydrogenase demethylates sarcosine, a byproduct of homocysteine metabolism. The ExHC rats with dysfunctional Sardh developed hypersarcosinemia and homocysteinemia, a risk factor for atherosclerosis, with or without dietary cholesterol. The mRNA expression of Bhmt, a homocysteine metabolic enzyme and the hepatic content of betaine (trimethylglycine), a methyl donor for homocysteine methylation were low in ExHC rats. Results suggest that homocysteine metabolism rendered fragile by a shortage of betaine results in homocysteinemia, and that Smek2 dysfunction causes abnormalities in sarcosine and homocysteine metabolism.
Collapse
|
2
|
Yuan X, Minobe Y, Tanaka Y, Fukuda Y, Furukawa Y, Miyago M, Mizokami T, Tsai WT, Jiang Z, Tong LT, Akasaka T, Shirouchi B, Toyosawa Y, Kumamaru T, Sato M. α-globulin-rich rice cultivar, low glutelin content-1 (LGC-1), decreases serum cholesterol concentration in exogenously hypercholesterolemic rats. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2021; 101:6417-6423. [PMID: 33982308 DOI: 10.1002/jsfa.11312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 01/19/2021] [Accepted: 05/12/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Rice α-globulin has been reported to have serum cholesterol-lowering activity in rats. However, it is still unclear whether α-globulin exerts this effect when taken as one of the dietary components. In the present study, we investigated the effect of two cultivars of rice, low glutelin content (LGC)-1 and LGC-Jun, on reducing serum cholesterol in exogenously hypercholesterolemic (ExHC) rats. LGC-1 is enriched in α-globulin (10.6 mg g-1 rice flour, which is an approximately 1.5 times higher α-globulin content than in Koshihikari a predominant rice cultivar in Japan), whereas LGC-Jun is a globulin-negative cultivar. METHODS ExHC rats, the model strain of diet-induced hypercholesterolemia, were fed 50% LGC-1 or LGC-Jun and 0.5% cholesterol-containing diets for 2 weeks, followed by measurement of cholesterol metabolism parameters in serum and tissues. RESULTS Serum cholesterol and non-high-density lipoprotein cholesterol levels were significantly lower in the LGC-1 group compared to the LGC-Jun group. Cholesterol intestinal absorption markers, hepatic and serum levels of campesterol and β-sitosterol, and lymphatic cholesterol transport were not different between the two groups. Levels of 7α-hydroxycholesterol, an intermediate of bile acid synthesis, showed a downward trend in the livers of rats that were fed LGC-1 (P = 0.098). There was a significant decrease in the hepatic mRNA expression of Cyp7a1 (a synthetic enzyme for 7α-hydroxycholesterol) in the LGC-1 group compared to the LGC-Jun group. CONCLUSION Dietary LGC-1 significantly decreased serum cholesterol levels in ExHC rats. The possible mechanism for the cholesterol-lowering activity of LGC-1 is partial inhibition of bile acid and cholesterol synthesis in the liver. © 2021 Society of Chemical Industry.
Collapse
Affiliation(s)
- Xingyu Yuan
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Yutaro Minobe
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Yasutake Tanaka
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Yumi Fukuda
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Yumiko Furukawa
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Motonori Miyago
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Takuya Mizokami
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Wei-Ting Tsai
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Zhe Jiang
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Li-Tao Tong
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Taiki Akasaka
- Center for Advanced Instrumental and Educational Supports, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Bungo Shirouchi
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Yoshiko Toyosawa
- Laboratory of Plant Genetic Resources, Institute of Genetic Resources, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Toshihiro Kumamaru
- Laboratory of Plant Genetic Resources, Institute of Genetic Resources, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Masao Sato
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| |
Collapse
|
3
|
Tanaka Y, Ono M, Miyago M, Suzuki T, Miyazaki Y, Kawano M, Asahina M, Shirouchi B, Imaizumi K, Sato M. Low utilization of glucose in the liver causes diet-induced hypercholesterolemia in exogenously hypercholesterolemic rats. PLoS One 2020; 15:e0229669. [PMID: 32163433 PMCID: PMC7067558 DOI: 10.1371/journal.pone.0229669] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 02/12/2020] [Indexed: 12/25/2022] Open
Abstract
Exogenously hypercholesterolemic (ExHC) rats develop diet-induced hypercholesterolemia (DIHC) when fed with dietary cholesterol. Previously, we reported that, under the high-sucrose-diet-feeding condition, a loss-of-function mutation in Smek2 results in low activity of fatty acid synthase (FAS) followed by the shortage of hepatic triacylglycerol content in ExHC rats and the onset of DIHC. However, the relationship between the Smek2 mutation and FAS dysfunction is still unclear. Here, we focused on carbohydrate metabolism, which provides substrates for FAS, and analyzed carbohydrate and lipid metabolisms in ExHC rats to clarify how the deficit of Smek2 causes DIHC. Male ExHC and SD rats were fed high-sucrose or high-starch diets containing 1% cholesterol for 2 weeks. Serum cholesterol levels of the ExHC rats were higher, regardless of the dietary carbohydrate. Hepatic triacylglycerol levels were higher in only the SD rats fed the high-sucrose diet. Moreover, the ExHC rats exhibited a diabetes-like status and accumulation of hepatic glycogen and low hepatic mRNA levels of liver-type phosphofructokinase (Pfkl), which encodes a rate-limiting enzyme for glycolysis. These results suggest that the glucose utilization, particularly glycolysis, is impaired in the liver of ExHC rats. To evaluate how the diet with extremely low glucose affect to DIHC, ExHC.BN-Dihc2BN, a congenic strain that does not develop DIHC, and ExHC rats were fed a high-fructose diet containing 1% cholesterol for 2 weeks. The serum cholesterol and hepatic triacylglycerol levels were similar in the strains. Results of water-soluble metabolite analysis with primary hepatocytes, an increase in fructose-6-phosphate and decreases in succinate, malate and aspartate in ExHC rats, support impaired glycolysis in the ExHC rats. Thus, the Smek2 mutation causes abnormal hepatic glucose utilization via downregulation of Pfkl expression. This abnormal glucose metabolism disrupts hepatic fatty acid synthesis and causes DIHC in the ExHC rats.
Collapse
Affiliation(s)
- Yasutake Tanaka
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Masahiro Ono
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Motonori Miyago
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Takahisa Suzuki
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Yurika Miyazaki
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Michio Kawano
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Makoto Asahina
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Bungo Shirouchi
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Katsumi Imaizumi
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Masao Sato
- Department of Bioscience and Biotechnology, Laboratory of Nutrition Chemistry, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
- * E-mail:
| |
Collapse
|