SDF-1α inhibits hypoxia and serum deprivation-induced apoptosis in mesenchymal stem cells through PI3K/Akt and ERK1/2 signaling pathways

Bone marrow-derived mesenchymal stem cells (BMSCs) have been demonstrated to be a promising cell sources for cardiac regeneration. Poor survival rate of transplanted BMSCs in infarcted myocardium attenuated its clinical application. It’s reported that stromal-derived factor-1 (SDF-1) could protect progenitor cells including endothelial progenitor cells and embryonic stem cells from apoptosis. But little is known whether SDF-1α protein has the same protective effects on BMSCs under conditions of hypoxia and serum deprivation (hypoxia/SD). In present study, we verified that SDF-1α (0.50–2.0 μg/ml) inhibited hypoxia/SD induced apoptosis of BMSCs through mitochondrial pathway. After administration of SDF-1α, the loss of mitochondrial membrane potential and cytochrome c released from mitochondria to cytosol were significantly inhibited, and caspase 3 activity also declined. Furthermore, the effect of SDF-1α on mitochondrial pathway was neutralized by using PI3K inhibitor (Wortmannin) and ERK1/2 inhibitor (U0126). Our observations suggested that SDF-1α inhibits hypoxia/SD induced BMSCs apoptosis through PI3K/Akt and ERK1/2 signaling pathways. These data also imply that the anti-apoptotic effect mediated by SDF-1α may enhance cell survival after cell transplantation.     

Function identification of MdTIR1 in apple root growth benefited from the predicted MdPPI network

Protein–protein interaction (PPI) network analysis is an effective method to identify key proteins during plant development, especially in species for which basic molecular research is lacking, such as apple (Malus domestica). Here, an MdPPI network containing 30 806 PPIs was inferred in apple and its quality and reliability were rigorously verified. Subsequently, a root‐growth subnetwork was extracted to screen for critical proteins in root growth. Because hormone‐related proteins occupied the largest proportion of critical proteins, a hormone‐related sub‐subnetwork was further extracted from the root‐growth subnetwork. Among these proteins, auxin‐related M. domestica TRANSPORT INHIBITOR RESISTANT 1 (MdTIR1) served as the central, high‐degree node, implying that this protein exerts essential roles in root growth. Furthermore, transgenic apple roots overexpressing an MdTIR1 transgene displayed increased primary root elongation. Expression analysis showed that MdTIR1 significantly upregulated auxin‐responsive genes in apple roots, indicating that it mediates root growth in an auxin‐dependent manner. Further experimental validation revealed that MdTIR1 interacted with and accelerated the degradation of MdIAA28, MdIAA43, and MdIAA46. Thus, MdTIR1‐mediated degradation of MdIAAs is critical in auxin signal transduction and root growth regulation in apple. Moreover, our network analysis and high‐degree node screening provide a novel research technique for more generally characterizing molecular mechanisms.     

Genome-wide analysis of the RING finger gene family in apple

The RING finger protein family plays a crucial role in plant growth and development and in response to biotic and abiotic stresses. However, no detailed information concerning this family is available for apple (Malus × domestica L. Borkh) due to the limited information on whole genome sequences. In this study, 688 RING domains in 663 predicted proteins were identified in apple. Based on the spacing between metal ligands or substitutions at one or more of the metal ligand positions, nine RING types were identified: RING-H2, RING-HC, RING-C2, RING-v, RING-D, RING-S/T, RING-G, RING-mH2, and RING-mHC, in which the first seven types were described previously in Arabidopsis, while the latter two were newly identified in apple. Proteins containing RING finger motifs were further classified into 57 groups according to the different known or unknown domains outside the RING domains. A total of 643 retrieved proteins appear to be distributed over all 17 linkage groups with different densities. Microarray and expressed sequence tag data revealed that only a few of these RING finger proteins may be involved in fruit development. As a first step towards genome-wide analyses of the RING-containing genes in apple, our results provide valuable information for understanding the classification and putative functions of the RING finger gene family in higher plants.     

猪鼻支原体P37蛋白相互作用蛋白的筛选与鉴定

既往工作表明,胃癌组织中有较高的猪鼻支原体感染率,猪鼻支原体的主要膜蛋白P37能够诱导外周血单核细胞释放肿瘤坏死因子（TNF）.为了深入研究P37的作用机制,利用酵母双杂交系统筛选与P37蛋白相互作用的蛋白质分子.首先,将编码P37全长的cDNA克隆到pGBKT7载体中,构建“诱饵”表达载体pGBKT7-p37,以此筛选人胎盘组织cDNA表达文库.在2.6×10⁶个克隆中,筛选到一株能与P37相互作用的阳性克隆,序列测定表明,该阳性克隆编码人视网膜色素上皮细胞蛋白（Norpeg蛋白）.在此基础上经GST-Pull Down实验,进一步证实Norpeg蛋白确能与P37相互作用,为进一步研究P37对细胞的作用机制奠定了基础.     

Antisense suppression of an acid invertase gene (MAI1) in muskmelon alters plant growth and fruit development

To unravel the roles of soluble acid invertase in muskmelon (Cucumis melo L.), its activity in transgenic muskmelon plants was reduced by an antisense approach. For this purpose, a 1038 bp cDNA fragment of muskmelon soluble acid invertase was expressed in antisense orientation behind the 35S promoter of the cauliflower mosaic virus. The phenotype of the antisense plants clearly differed from that of control plants. The transgenic plant leaves were markedly smaller, and the stems were obviously thinner. Transmission electron microscopy revealed that degradation of the chloroplast membrane occurred in transgenic leaves and the number of grana in the chloroplast was significantly reduced, suggesting that the slow growth and weaker phenotype of the transgenic plants may be due to damage to the chloroplast ultrastructure, which in turn resulted in a decrease in net photosynthetic rate. The sucrose concentration increased and levels of acid invertase decreased in transgenic fruit, and the fruit size was 60% smaller than that of the control. In addition, transgenic fruit reached full-slip at 25 d after pollination (DAP), approximately 5 d before the control fruit (full-slip at 30 DAP), and this accelerated maturity correlated with a dramatic elevation of ethylene production at the later stages of fruit development. Together, these results suggest that soluble acid invertase not only plays an important role during muskmelon plant and fruit development but also controls the sucrose content in muskmelon fruit.     

版纳小型猪近交系椎骨、肋骨的形态及生物力学研究

本研究观察了版纳小型猪近交系椎骨、肋骨的解剖学、组织学形态,并对其腰椎进行轴向载荷压缩试验。小型猪椎骨及肋骨在解剖学、组织学方面与人近似,其腰椎能承受人类正常生理载荷。因此,版纳小型猪椎骨、肋骨可以作为异种骨移植的材料。