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Mena [mammalian Ena (Enabled)]/VASP (vasodilator-stimulated phosphoprotein) proteins are the homologues of Drosophila Ena. In Drosophila, Ena is a substrate of the tyrosine kinase DAbl (Drosophila Abl). However, the link between Abl and the Mena/VASP family is not fully understood in mammals. We previously reported that Abi-1 (Abl interactor 1) promotes phosphorylation of Mena and BCAP (B-cell adaptor for phosphoinositide 3-kinase) by bridging the interaction between c-Abl and the substrate. In the present study we have identified VASP, another member of the Mena/VASP family, as an Abi-1-bridged substrate of Abl. VASP is phosphorylated by Abl when Abi-1 is co-expressed. We also found that VASP interacted with Abi-1 both in vitro and in vivo. VASP was tyrosine-phosphorylated in Bcr-Abl-positive leukaemic cells in an Abi-1-dependent manner. Co-expression of c-Abl and Abi-1 or the phosphomimetic Y39D mutation in VASP resulted in less accumulation of VASP at focal adhesions. VASP Y39D had a reduced affinity to the proline-rich region of zyxin. Interestingly, overexpression of both phosphomimetic and unphosphorylated forms of VASP, but not wild-type VASP, impaired adhesion of K562 cells to fibronectin. These results suggest that the phosphorylation and dephosphorylation cycle of VASP by the Abi-1-bridged mechanism regulates association of VASP with focal adhesions, which may regulate adhesion of Bcr-Abl-transformed leukaemic cells.

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BackgroundThe effect of the redox state of human serum albumin (HSA) on the antioxidant properties of the entire body has been a focus of recent research. The usefulness of HSA redox state as a biomarker for reducing oxidative stress has been investigated in clinical settings; however, evidence for its significance as a health index in non-clinical settings is yet to be established. This study aimed to examine the associations between HSA redox state and the atherosclerotic indices of carotid intima-media thickness (IMT) and plaque formation in a rural Japanese population.MethodsWe conducted a cross-sectional study as part of a health check-up program in the rural area of Hokkaido, Japan, at the end of August 2013. A total of 281 residents (124 men and 157 women) were included in the final analysis. Lifestyle-related data were obtained through a self-reported questionnaire, and ultrasound examinations were performed to measure IMT and determine plaque formation. The high-performance liquid chromatography postcolumn bromocresol green method was used to separate HSA into human nonmercaptalbumin and human mercaptalbumin (HMA).ResultsWe found a significant negative relationship between the fraction of HMA [f(HMA)] and IMT (standardized β = − 0.132, p = 0.03). Moreover, f(HMA) was significantly associated with plaque formation (p < 0.01) with an odds ratio of 0.89 (95% confidence interval, 0.81–0.97) for every 10% increment in f(HMA).ConclusionsWe found that the HSA redox state, as determined by f(HMA), was associated with atherosclerotic indices in Japanese subjects. These results suggest that the HSA redox state indicates the risk of developing atherosclerosis.