Starch synthase IIIa and starch branching enzyme IIb-deficient mutant rice line ameliorates pancreatic insulin secretion in rats: screening and evaluating mutant rice lines with antidiabetic functionalities

Abstract

Diabetes mellitus is a metabolic disease spreading worldwide that has been reported to worsen the development and progression of other diseases (cancer, vascular diseases and dementia). To establish functional rice lines with anti-postprandial hyperglycaemic effects, we developed mutant rice lines, which lack one or two gene(s) related to starch synthesis, and evaluated their effects. Powder of mutant rice lines or other grains was loaded to rats fasted overnight (oral grain powder loading test). Incremental area under time-concentration curves (iAUC) were calculated with monitored blood glucose levels. Rice lines with anti-postprandial hyperglycaemic effects were separated by cluster analysis with calculated iAUC. A double mutant rice #4019 (starch synthase IIIa (ss3a)/branching enzyme IIb (be2b)), one of the screened mutant rice lines, was fed to Goto-Kakizaki (GK) rats, an animal model for type 2 diabetes, for 5 weeks. Plasma levels of C-peptide, a marker of pancreatic insulin secretion, were measured with ELISA. For in vitro study, a rat pancreatic cell line was cultured with a medium containing rat serum which was sampled from rats fed #4019 diet for 2 d. After 24-h of incubation, an insulin secretion test was performed. Through the oral rice powder loading test, seven rice lines were identified as antidiabetic rice lines. The intake of #4019 diet increased plasma C-peptide levels of GK rats. This result was also observed in vitro. In rat serum added to cell medium, ornithine was significantly increased by the intake of #4019. In conclusion, the mutant rice #4019 promoted pancreatic insulin secretion via elevation of serum ornithine levels.

Breeding for three-line japonica hybrid rice combinations with high resistant starch content using molecular marker-assisted selection

“…RS content in steamed rice with the OsSBEIIb mutant is high ( Tsuiki et al 2016 ). Further, Tanaka et al (2018) reported that starch synthase IIIa and SBEIIb -deficient mutant rice could ameliorate pancreatic insulin secretion in rats. These results are consistent with our previous studies of Jiangtangdao 1 with sbe3-rs .…”

Low utilization of glucose in the liver causes diet-induced hypercholesterolemia in exogenously hypercholesterolemic rats

“…Water-soluble metabolites in the rat primary hepatocyte lysate were analyzed according to a previously described protocol [24]. Same-cell concentrations of primary hepatocytes of ExHC and Congenic rats were collected in PBS and then sonicated to obtain the cell lysate.…”

“…Same-cell concentrations of primary hepatocytes of ExHC and Congenic rats were collected in PBS and then sonicated to obtain the cell lysate. This lysate (50 μl) was used for the metabolome analysis performed as described previously [24]. Metabolites extracted from cell lysate were derivatized with Methoxyamine hydrochloride and N-Methyl-N-trimethylsilyl-trifluoroacetamide and detected with gas chromatography mass spectroscopy analysis (GCMS-QP2020, SHIMAZU).…”

Changes in kernel properties, in situ gelatinization, and physicochemical properties of waxy rice with inhibition of starch branching enzyme during cooking

“…AC is a major component determining the eating and cooking quality (Tian et al ., ). At present, high‐RS rice, which is usually generated through deficiency of SSSIIIa or SBEIIb in rice, has high AC in kernels (Butardo et al ., ; Yang et al ., ; Zhu et al ., ; Zhou et al ., ; Itoh et al ., ; Tanaka et al ., ; Wada et al ., ). However, rice kernels with greater AC become more difficult to cook and harder, drier in texture, resulting in a poor cooking and eating quality.…”