LPA in neural cell development

Lysophosphatidic acid (LPA) elicits diverse cellular responses through cell surface LPA receptors in nervous system-derived cells and cell lines. The developing nervous system is one of the major loci for LPA receptor expression. Recent studies have also revealed that metabolic pathways of LPA are present in the nervous system. A growing body of literature suggests a crucial role for LPA in neuronal development processes, including neurogenesis, neuronal migration, neuritogenesis, and myelination.     

Soybean glycinin A1aB1b subunit has a molecular chaperone-like function to assist folding of the other subunit having low folding ability

Soybean (Glycine max L.) glycinin is composed of five subunits which are classified into two groups (group I: A1aB1b, A1bB2, and A2B1a; group II: A3B4 and A5A4B3). All the common soybean cultivars contain both group I and II subunits (Maruyama, N. et al., Phytochemistry, 64, 701-708 (2003)). The biosynthesis of group I starts earlier compared with that of the A3B4 subunit during seed development (Meinke, D.W. et al., Planta, 153, 130-139 (1981)). We have revealed that group I A1aB1b was mostly expressed as a soluble protein, but that A3B4 was expressed mainly as an insoluble protein in Escherichia coli under the same expression conditions; namely, A1aB1b had higher folding ability than A3B4. We therefore assumed that A1aB1b assists folding of group II subunits like a molecular chaperone does. In order to ascertain this, A1aB1b and A3B4 were co-expressed in E. coli. All of the expressed proteins of A3B4 were recovered in a soluble fraction. To confirm this result, we also co-expressed A1aB1b with modified A3B4 versions having extremely low folding ability. All expressed modified A3B4 versions were soluble. These results clearly suggest that A1aB1b has a molecular chaperone-like function in their folding.     

Introduction of DPR, an enterostatin fragment peptide, into soybean beta-conglycinin alpha' subunit by site-directed mutagenesis

DPR, a fragment peptide of enterostatin (VPDPR) having hypocholesterolemic activity, was introduced into the three homologous sites, EPR, DYR, and DPI, in the soybean beta-conglycinin alpha' subunit by site-directed mutagenesis. The modified beta-conglycinin was expressed in Escherichia coli and recovered in the soluble fraction. After purification on ion-exchange HPLC, the modified beta-conglycinin was digested by trypsin to release integrated DPR. The yield of DPR from 1 mole of the modified beta-conglycinin was 1.2 mole.     

Suppressive effect of a hot water extract of adzuki beans (Vigna angularis) on hyperglycemia after sucrose loading in mice and diabetic rats

A hot water extract obtained by boiling adzuki beans (Vigna angularis) to produce bean paste for Japanese cake showed inhibitory activity against alpha-glucosidase, alpha-amylase, maltase, sucrase, and isomaltase after HP-20 column chromatography. The IC(50) values for each hydrolylase were 0.78 mg/ml (alpha-amylase), 2.45 mg/ml (maltase), 5.37 mg/ml (sucrase), and 1.75 mg/ml (isomaltase). The active fraction showed potential hypoglycemic activity in both normal mice and streptozotocin (STZ)-induced diabetic rats after an oral administration of sucrose, but did not show any effect on the blood glucose concentration after glucose administration, suggesting that the active fraction suppressed the postprandial blood glucose level by inhibiting alpha-glucosidase and alpha-amylase, irrespective of the endogenous blood insulin level.     

The composition of newly synthesized proteins in the endoplasmic reticulum determines the transport pathways of soybean seed storage proteins

Glycinin (11S) and beta-conglycinin (7S) are major storage proteins in soybean (Glycine max L.) seeds and accumulate in the protein storage vacuole (PSV). These proteins are synthesized in the endoplasmic reticulum (ER) and transported to the PSV by vesicles. Electron microscopic analysis of developing soybean cotyledons of the wild type and mutants with storage protein composition different from that of the wild type showed that there are two transport pathways: one is via the Golgi and the other bypasses it. Golgi-derived vesicles were observed in all lines used in this study and formed smooth dense bodies with a diameter of 0.5 to several micrometers. ER-derived protein bodies (PBs) with a diameter of 0.3-0.5 microm were observed at high frequency in the mutants containing higher amount of 11S group I subunit than the wild type, whereas they were hardly observed in the mutants lacking 11S group I subunit. These indicate that pro11S group I may affect the formation of PBs. Thus, the composition of newly synthesized proteins in the ER is important in the selection of the transport pathways.     

Serum concentrations of androstenediol and androstenediol sulfate, and their relation to cytokine production during and after normal pregnancy

Since it is known that androstenediol (ADIOL) has potent immunoregulatory effects, changes in ADIOL levels during and after pregnancy might affect the maternal immune system. We examined serum concentrations of ADIOL and androstenediol 3-sulfate (ADIOLS) together with IFN-gamma and IL-4 production levels during pregnancy and after delivery up to 10-11 months postpartum. The subjects were 73 normal pregnant, 76 normal postpartum, and 28 normal non-pregnant women. ADIOL and ADIOLS were measured using EIA and GC/MS, respectively. The cytokine levels in the supernatant of whole-blood cultures stimulated with phorbol 12-myristate 13-acetate and ionomycin were measured using ELISA. ADIOL levels significantly decreased compared to non-pregnant levels in the first trimester (P < 0.05) and were reversed in the third trimester (P < 0.05). After pregnancy, ADIOL levels gradually declined, and a significant decrease was observed at 10-11 months postpartum (P < 0.05). ADIOLS levels were significantly lower in the third trimester (P < 0.05) and significantly higher at the first month postpartum (P < 0.001) compared to non-pregnant women. IFN-gamma and IL-4 levels decreased during pregnancy and subsequently increased postpartum. On the other hand, we found significant negative correlations between ADIOL concentrations and production levels of IFN-gamma (P < 0.05) or IL-4 (P < 0.05). These findings suggest that ADIOL may be involved in modifying the maternal immune response during and after pregnancy.