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Articles by Z Yan
Total Records ( 2 ) for Z Yan
  Q Feng , Z Fang , Z Yan , R Xing , L Xie and R. Zhang
 

We previously identified a matrix protein, MSI7, from pearl oyster Pinctada fucata. According to the structural analysis, the DGD site in the N-terminal of MSI7 is crucial for its role in the shell formation. In this study, we expressed a series of recombinant MSI7 proteins, including the wild-type and several mutants directed at the DGD site, using an Escherichia coli expression system to reveal the structure–function relationship of MSI7. Furthermore, in vitro crystallization, crystallization speed assay, and circular dichroism spectrometry were carried out. Results indicated that wild-type MSI7 could induce the nucleation of aragonite and inhibit the crystallization of calcite. However, none of the mutants could induce the nucleation of aragonite, but all of them could inhibit the crystallization of calcite to some extent. And all the proteins accelerated the crystallization process. Taken together, the results indicated that MSI7 could contribute to aragonite crystallization by inducing the nucleation of aragonite and inhibiting the crystallization of calcite, which agrees with our prediction about its role in the nacreous layer formation of the shell. The DGD site was critical for the induction of the nucleation of aragonite.

  V. A Lira , C. R Benton , Z Yan and A. Bonen
 

The peroxisome proliferator-activated receptor- (PPAR) coactivator-1 (PGC-1) is a major regulator of exercise-induced phenotypic adaptation and substrate utilization. We provide an overview of 1) the role of PGC-1 in exercise-mediated muscle adaptation and 2) the possible insulin-sensitizing role of PGC-1. To these ends, the following questions are addressed. 1) How is PGC-1 regulated, 2) what adaptations are indeed dependent on PGC-1 action, 3) is PGC-1 altered in insulin resistance, and 4) are PGC-1-knockout and -transgenic mice suitable models for examining therapeutic potential of this coactivator? In skeletal muscle, an orchestrated signaling network, including Ca2+-dependent pathways, reactive oxygen species (ROS), nitric oxide (NO), AMP-dependent protein kinase (AMPK), and p38 MAPK, is involved in the control of contractile protein expression, angiogenesis, mitochondrial biogenesis, and other adaptations. However, the p38 MAPK/PGC-1 regulatory axis has been confirmed to be required for exercise-induced angiogenesis and mitochondrial biogenesis but not for fiber type transformation. With respect to a potential insulin-sensitizing role of PGC-1, human studies on type 2 diabetes suggest that PGC-1 and its target genes are only modestly downregulated (≤34%). However, studies in PGC-1-knockout or PGC-1-transgenic mice have provided unexpected anomalies, which appear to suggest that PGC-1 does not have an insulin-sensitizing role. In contrast, a modest (~25%) upregulation of PGC-1, within physiological limits, does improve mitochondrial biogenesis, fatty acid oxidation, and insulin sensitivity in healthy and insulin-resistant skeletal muscle. Taken altogether, there is substantial evidence that the p38 MAPK-PGC-1 regulatory axis is critical for exercise-induced metabolic adaptations in skeletal muscle, and strategies that upregulate PGC-1, within physiological limits, have revealed its insulin-sensitizing effects.

 
 
 
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