Synuclein proteins of the pufferfish Fugu rubripes: sequences and functional characterization

In humans, three genes encode the related alpha-, beta-, and gamma-synucleins, which function as lipid-binding proteins in vitro. They are being widely studied, mainly because of the central involvement of alpha-synuclein in a number of neurodegenerative diseases, including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. In these diseases, the normally soluble alpha-synuclein assembles into abnormal filaments. Here, we have identified and characterized the synuclein gene family from the pufferfish Fugu rubripes. It consists of four genes, which encode alpha-, beta-, gamma1-, and gamma2-synucleins. They range from 113 to 127 amino acids in length and share many of the characteristics of human synucleins, including the presence of imperfect amino-terminal repeats of 11 amino acids, a hydrophobic middle region, and a negatively charged carboxy-terminus. All four synucleins are expressed in the Fugu brain. Recombinant Fugu synucleins exhibited differential liposome binding, which was strongest for alpha-synuclein, followed by beta-, gamma2-, and gamma1-synucleins. In assembly experiments, Fugu alpha-, gamma1-, and gamma2-synucleins formed filaments more readily than human alpha-synuclein. Fugu beta-synuclein, by contrast, failed to assemble in bulk. Filament assembly of synucleins was directly proportional to their degree of hydrophobicity and their tendency to form beta-sheet structure, and correlated inversely with their net charge.     

Acarbose, an alpha-glucosidase inhibitor, improves endothelial dysfunction in Goto-Kakizaki rats exhibiting repetitive blood glucose fluctuation

Several epidemiological studies have revealed that subjects with postprandial hyperglycemia are at increased risk of cardiovascular disease. However, the impact of postprandial hyperglycemia and its treatment on endothelial function has not been clarified yet. In this study, Goto-Kakizaki (GK) rats, a non-obese type 2 diabetes model, fed twice daily were used as a model of repetitive postprandial glucose spikes. We investigated the endothelial function in these rats treated or untreated with acarbose, an alpha-glucosidase inhibitor. Administration of acarbose for 12 weeks markedly improved postprandial hyperglycemia, postprandial insulin level, total cholesterol, triglyceride, and free fatty acid level in GK rats. Furthermore, acarbose efficiently reduced the number of monocytes adherent to aortic endothelial layer, improved acetylcholine-dependent vasodilatation, and reduced intimal thickening of the aorta. While it is generally regarded that repetitive postprandial hyperglycemia is associated with the onset of cardiovascular diseases, our data demonstrated that acarbose treatment efficiently ameliorated endothelial dysfunction and reduced intimal thickening, thus adding support to the protective effect of acarbose against the onset of cardiovascular disease.     

Transgenic tobacco plants producing caffeine: a potential new strategy for insect pest control

Caffeine (1,3,7–trimethylxanthine) is one of the most widely used plant secondary metabolites, primarily as a stimulant and an ingredient in drugs. In nature, caffeine is believed to function in chemical defense, acting as an antiherbivory and allelopathic agent, and therefore it might be employed to protect agriculturally important crop plants. In coffee plants, caffeine is synthesized from the precursor xanthosine in four steps, three N-methylations and removal of ribose. We had previously isolated genes encoding three distinct N-methyltransferases, and we demonstrated production of recombinant enzymes that yielded caffeine in in vitro reconstitution experiments. When these caffeine biosynthetic pathway genes were simultaneously expressed in tobacco plants (Nicotiana tabacum), caffeine was successfully produced up to 5 μg/g fresh weight in leaves. The leaves were unpalatable to tobacco cutworms (Spodoptera litura). This repellent action appeared to be more widely␣applicable to lepidopteran caterpillars as observed with small white (Pieris rapae) fed on Chinese cabbages that had been top-treated with caffeine. Our recent results suggest a novel approach to strengthen anti-herbivore traits by producing caffeine in crop plants.     

Amphiphilic molecular gels from ω-aminoalkylated l-glutamic acid derivatives with unique chiroptical properties

Self-assembling amphiphiles with unique chiroptical properties were derived from l-glutamic acid through ω-aminoalkylation and double long-chain alkylation. These amphiphiles can disperse in various solvents ranging from water to n-hexane. TEM and SEM observations indicate that the improvement in dispersity is induced by the formation of tubular and/or fibrillar aggregates with nanosized diameters, which makes these amphiphiles similar to aqueous lipid membrane systems. Spectroscopic observations, such as UV–visible and CD spectroscopies indicate that the aggregates are constructed on the basis of S- and R-chirally ordered structures through interamide interactions in water and organic media, respectively, and that these chiroptical properties can be controlled thermotropically and lyotropically. It is also reported that the chiral assemblies provide specific binding sites for achiral molecules and then induce chirality for the bonded molecules. Further, the applicability of the amphiphiles to template polymerization is discussed.     

Increased expression of co-chaperone HOP with HSP90 and HSC70 and complex formation in human colonic carcinoma

Co-chaperone HOP (also called stress-inducible protein 1) is a co-chaperone that interacts with the cytosolic 70-kDa heat shock protein (HSP70) and 90-kDa heat shock protein (HSP90) families using different tetratricopeptide repeat domains. HOP plays crucial roles in the productive folding of substrate proteins by controlling the chaperone activities of HSP70 and HSP90. Here, we examined the levels of HOP, HSC70 (cognate of HSP70, also called HSP73), and HSP90 in the tumor tissues from colon cancer patients, in comparison with the non-tumor tissues from the same patients. Expression level of HOP was significantly increased in the tumor tissues (68% of patients, n = 19). Levels of HSC70 and HSP90 were also increased in the tumor tissues (95% and 74% of patients, respectively), and the HOP level was highly correlated with those of HSP90 (r = 0.77, p < 0.001) and HSC70 (r = 0.68, p < 0.01). Immunoprecipitation experiments indicated that HOP complexes with HSC70 or HSP90 in the tumor tissues. These data are consistent with increased formation of co-chaperone complexes in colon tumor specimens compared to adjacent normal tissue and could reflect a role for HOP in this process.