Kinesin superfamily protein UNC-104, a member of the kinesin-3 family, transports synaptic vesicle precursors (SVPs). In this study, the number of active UNC-104 molecules hauling a single SVP in axons in the worm Caenorhabditis elegans was counted by applying a newly developed non-invasive force measurement technique. The distribution of the force acting on a SVP transported by UNC-104 was spread out over several clusters, implying the presence of several force-producing units (FPUs). We then compared the number of FPUs in the wild-type worms with that in arl-8 gene-deletion mutant worms.ARL-8 is a SVP-bound arf-like small guanosine triphosphatase, and is known to promote unlocking of the autoinhibition of the motor, which is critical for avoiding unnecessary consumption of adenosine triphosphate when the motor does not bind to a SVP. There were fewer FPUs in the arl-8 mutant worms. This finding indicates that a lack of ARL-8 decreased the number of active UNC-104 motors, which then led to a decrease in the number of motors responsible for SVP transport.

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Background: Aberrant DNA methylation is one of the major events in carcinogenesis. Promoter DNA methylation is also present in various non-neoplastic tissues including gastric epithelium as age-related phenomenon, suggesting that it occurs early in the process of tumorigenesis. Aim: We aimed to clarify the relationship of aberrant DNA methylation in non-neoplastic gastric epithelia with the risk of gastric cancer, Helicobactor pylori infection, and the degree of H. pylori-induced gastritis. Methods: 89 patients enrolled in this study. The status of aberrant DNA methylation was compared in two groups of patients: 43 cases with gastric cancer (mean age 65.9 years [29–91], F:M = 0.30, intestinal type [n = 25], diffuse type [n = 18]) and 46 age- and sex-matched patients without gastric cancer (peptic ulcer diseases [n = 11], gastritis [n = 35]) as a control group. Genomic DNA was extracted directly from non-neoplastic epithelia of antral biopsies obtained by endoscopy. The promoter methylation status of the p14 and p21 genes was determined by methylation-specific-polymerase chain reaction (MSP). The promoter methylation status of the p16 gene was quantified by digital densitographic analysis following MSP. The degree of gastritis in the antrum was assessed according to the updated Sydney system. The PG I/II ratio was calculated based on the data of serum PG I and PG II levels measured by radioimmunoassay. Results: In all 89 subjects, CpG island methylation was found in 25.8% for p14, 52.8% for p16, 1.1% for p21. Among non-cancer patients, the methylation frequency of the p14 gene was significantly higher in H. pylori-positive than in H. pylori-negative patients (38.5 vs. 10.0%, p = 0.03). The mean (± SD) methylation levels of the p16 gene in non-neoplastic gastric epithelium was significantly higher in gastric cancer cases both in all patients and in H. pylori-positive patients (0.45 ± 0.31 vs. 0.20 ± 0.17; p = 0.019, 0.45 ± 0.31 vs. 0.20 ± 0.17; p = 0.016, respectively). The methylation level of the p16 gene was also associated with the presence of intestinal-type gastric cancer (p = 0.017). The methylation level of the p16 gene was significantly higher in patients with intestinal metaplasia (IM) than those without (p = 0.04). Furthermore, the methylation level of the p16 gene was correlated with lower PG l/ll ratio (p = 0.04). The methylation of the p21gene was found in only 1 patient with gastric cancer. Conclusions: Our data suggest that promoter of the p14 gene may be one of the specific regions whose methylation is closely associated with H. pylori infection. Methylation levels of the p16 gene seem to be accumulated in the progression of gastric mucosal atrophy and IM, and thus may be associated with the presence of gastric cancer especially for intestinal-type histopathology.