Lingwen Ying1, Xiaojing Ma1, Jun Yin2, Yufei Wang1, Xingxing He1, Jiahui Peng1, Yuqian Bao1, Jian Zhou3, Weiping Jia1. 1. Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Clinical Center for Diabetes, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, 600 Yishan Road, Shanghai, 200233, China. 2. Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Clinical Center for Diabetes, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, 600 Yishan Road, Shanghai, 200233, China. yinjun@sjtu.edu.cn. 3. Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Clinical Center for Diabetes, Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, 600 Yishan Road, Shanghai, 200233, China. zhoujian@sjtu.edu.cn.
Abstract
AIMS: Our previous studies demonstrated that serum 1,5-anhydroglucitol (1,5-AG) levels increased slightly rather than declined after an acute glucose load. Therefore, the current study aims at exploring the transport and metabolic characteristics of 1,5-AG, as well as the effect of glucose on 1,5-AG transport. METHODS: Km and Vmax were determined to measure the affinity of glucose oxidase (GOD) and hexokinase (HK) for 1,5-AG and glucose. HepG2, C2C12, and primary mouse hepatocytes were incubated for 2 h with 1,5-AG at concentrations of 0, 80, and 160 μg/mL. Then, intracellular and extracellular concentrations of 1,5-AG were measured before and after washing with PBS to evaluate the transport and metabolic rates of 1,5-AG. In addition, the influence of an acute glucose load on the transport of 1,5-AG was studied. RESULTS: The affinity of GOD and HK for 1,5-AG is 5 and 42.5% of that for glucose, respectively. Moreover, there is no de novo synthesis of 1,5-AG, and its metabolic rate is < 3%. After a 2 h incubation with additional 1,5-AG, the intracellular levels of 1,5-AG were 50-80% of extracellular levels. Moreover, intracellular 1,5-AG concentrations decreased rapidly and reached zero following the removal of 1,5-AG from the external medium. In addition, an acute glucose load can affect the dynamic balance of 1,5-AG, causing the intracellular 1,5-AG levels to decline significantly and the extracellular levels to increase slightly in HepG2 cells. CONCLUSIONS: Unlike glucose, 1,5-AG is hard to be metabolized in vivo, and its transport is influenced by an acute glucose load in hepatocytes.
AIMS: Our previous studies demonstrated that serum 1,5-anhydroglucitol (1,5-AG) levels increased slightly rather than declined after an acute glucose load. Therefore, the current study aims at exploring the transport and metabolic characteristics of 1,5-AG, as well as the effect of glucose on 1,5-AG transport. METHODS: Km and Vmax were determined to measure the affinity of glucose oxidase (GOD) and hexokinase (HK) for 1,5-AG and glucose. HepG2, C2C12, and primary mouse hepatocytes were incubated for 2 h with 1,5-AG at concentrations of 0, 80, and 160 μg/mL. Then, intracellular and extracellular concentrations of 1,5-AG were measured before and after washing with PBS to evaluate the transport and metabolic rates of 1,5-AG. In addition, the influence of an acute glucose load on the transport of 1,5-AG was studied. RESULTS: The affinity of GOD and HK for 1,5-AG is 5 and 42.5% of that for glucose, respectively. Moreover, there is no de novo synthesis of 1,5-AG, and its metabolic rate is < 3%. After a 2 h incubation with additional 1,5-AG, the intracellular levels of 1,5-AG were 50-80% of extracellular levels. Moreover, intracellular 1,5-AG concentrations decreased rapidly and reached zero following the removal of 1,5-AG from the external medium. In addition, an acute glucose load can affect the dynamic balance of 1,5-AG, causing the intracellular 1,5-AG levels to decline significantly and the extracellular levels to increase slightly in HepG2 cells. CONCLUSIONS: Unlike glucose, 1,5-AG is hard to be metabolized in vivo, and its transport is influenced by an acute glucose load in hepatocytes.
Entities:
Keywords:
1,5-anhydroglucitol; Glucose load; Glucose oxidase; Hexokinase; Metabolism; Transport
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