Interaction between Habitual Green Tea and Coffee Consumption and ACTN3 Genotype in Association with Skeletal Muscle Mass and Strength in Middle-Aged and Older Adults.

BACKGROUND: Recent studies have suggested the potential benefits of habitual coffee and green tea consumption on skeletal muscle health. However, it remains unclear whether these benefits are modified by genetic factors, particularly the alpha-actinin-3 (ACTN3) genotype, which is associated with the skeletal muscle phenotype. This study aimed to investigate the interaction between habitual coffee or green tea consumption and the ACTN3 genotype in association with skeletal muscle mass (SMM) and strength. METHODS: This cross-sectional study was conducted on 1,023 Japanese middle-aged and older adults (619 females, aged 45-74 years) living in the community. SMM was gauged using a bioelectrical impedance spectroscopy device, and handgrip strength (HGS) was used to measure muscle strength. The ACTN3 genotype (RR, RX, and XX) was determined from blood samples. Sex-specific linear regression models were used to analyze the interactions between coffee or green tea consumption and the ACTN3 genotype in association with SMM and HGS. RESULTS: In females, a significant interaction was observed between green tea consumption and the ACTN3 genotype in association with HGS (P interaction < 0.05). Furthermore, stratified analysis revealed a positive association between green tea consumption and HGS, specifically in females with the ACTN3 XX genotype (P trend < 0.05). In males, no significant interactions were observed between coffee or green tea consumption and the ACTN3 genotype in association with SMM or HGS (P interaction > 0.05). CONCLUSION: Our findings suggest that the skeletal muscle strength benefits associated with habitual green tea consumption may be contingent upon sex and the ACTN3 genotype.

Signal transduction and transcriptional regulation of angiogenesis.

When quiescent endothelial cells (ECs) are exposed to angiogenic factor such as VEGF; ECs express proteases to degrade extracellular matrices, migrate, proliferate and form new vessels. However, the molecular mechanism of these events is not fully characterized yet. We are studying the signal transduction and transcriptional regulation of angiogenesis. We investigated the properties of two VEGF receptors, Flt-1 and KDR, by using two newly developed blocking monoclonal antibodies (mAbs), i.e., anti-human Flt-1 mAb and anti-human KDR mAb. VEGF elicited induction of transcription factor Ets-1 in human umbilical vein endothelial cells (HUVECs). This induction was mediated by the KDR/Flt-1 heterodimer and the KDR homodimer. The role of transcription factor Ets-1 in angiogenesis was further clarified. We established both high and low Ets-1 expressing EC lines, and compared angiogenic properties of these cell lines with a parental murine EC line, MSS31. The growth rate was almost identical among three cell lines. It appeared that gene expressions of matrix metalloproteinases (MMP-1, MMP-3, and MMP-9) as well as integrin beta 3 were correlated with the level of Ets-1 expression. As a result, the invasiveness was enhanced in high Ets-1 expressing cells and reduced in low Ets-1 expressing cells compared with parental cells, and high Ets-1 expressing cells made more tube-like structures in type 1 collagen gel. These results indicate that Ets-1 is a principle transcription factor converting ECs to the angiogeneic phenotype.

Induction of Ets-1 in endothelial cells during reendothelialization after denuding injury.

Ets-1, a transcription factor, is induced in endothelial cells (ECs) during angiogenesis. Here, we investigated the expression of Ets-1 during reendothelialization. When a confluent monolayer of human umbilical vein endothelial cell line, ECV304, was denuded, ECV304 at the wound edge expressed Ets-1. An immunohistochemical analysis revealed that Ets-1 accumulated in migrating cells at the wound edge and returned to basal level when reendothelialization was accomplished. This induction of Ets-1 could be reproduced in in vivo denudation of rat aortic endothelium by a balloon catheter. The induction of Ets-1 in ECs after denudation was regulated transcriptionally, and humeral factors released from injured ECs might not be responsible. Mitogen-activated protein kinase (MAPK) activities were investigated to explore the mechanism of this induction. Although extracellular signal-regulated protein kinase 1/2 (ERK1/2), c-Jun N-terminal kinase 1 (JNK1), and p38 were activated after denudation, the activation of ERK1 and p38 was more rapid and prominent. PD98059, a specific MAPK/ERK kinase (MEK) 1 inhibitor, did not affect the induction of ets-1 mRNA, whereas SB203580, a specific p38 inhibitor, almost completely abrogated its induction. These results indicate that Ets-1 is induced in ECs after denudation through activation of p38. This induction of Ets-1 may be relevant for reendothelialization by regulating the expression of certain genes.

Ets-1 regulates angiogenesis by inducing the expression of urokinase-type plasminogen activator and matrix metalloproteinase-1 and the migration of vascular endothelial cells.

The coordinate induction of protease activities and cell migration is a principal feature of endothelial cells (ECs) invading the interstitial space in the initial step of angiogenesis. However, the molecular mechanisms of these events are not fully characterized. Ets-1 is a member of the ets gene family of transcription factors, which binds to the Ets binding motif in the cis-acting elements and regulates the expression of certain genes. Four typical angiogenic growth factors, aFGF, bFGF, VEGF, and EGF, induced the expression of ets-1 mRNA in either human umbilical vein endothelial cells (HUVECs), ECV-304 cells (immortalized HUVECs), or human omental microvascular endothelial cells (HOMECs). The expression of ets-1 reached its maximum at 2 hr after factor addition and then decreased to the basal level by 12 hr. For characterization of the role of Ets-1 in angiogenesis, ets-1 antisense and sense oligodeoxynucleotides (ODNs) were constructed. The ets-1 antisense ODN but not sense ODN efficiently blocked the synthesis of Ets-1 protein by human ECs in response to angiogenic growth factors. Moreover, the ets-1 antisense ODN but not sense ODN almost completely abolished the binding of endothelial cell extract to DNA containing the Ets binding motif. The expression of urokinase-type plasminogen activator and matrix metalloproteinase-1 and the migration of ECs in response to growth factors were significantly inhibited by ets-1 antisense ODN but not by sense ODN. Tube formation by HOMECs in type 1 collagen gel stimulated with EGF was abrogated by ets-1 antisense ODN. Finally, the expression of Ets-1 protein in ECs during angiogenesis in vivo was confirmed by an immunohistochemical analysis using a murine angiogenesis model. These results indicate that the induction of ets-1 mRNA is a mutual phenomenon in ECs stimulated with angiogenic growth factors. Ets-1 appears to play an important role in angiogenesis, regulating the expression of proteases and the migration of ECs.