Gene expression programs of human smooth muscle cells: tissue-specific differentiation and prognostic significance in breast cancers

Smooth muscle is present in a wide variety of anatomical locations, such as blood vessels, various visceral organs, and hair follicles. Contraction of smooth muscle is central to functions as diverse as peristalsis, urination, respiration, and the maintenance of vascular tone. Despite the varied physiological roles of smooth muscle cells (SMCs), we possess only a limited knowledge of the heterogeneity underlying their functional and anatomic specializations. As a step toward understanding the intrinsic differences between SMCs from different anatomical locations, we used DNA microarrays to profile global gene expression patterns in 36 SMC samples from various tissues after propagation under defined conditions in cell culture. Significant variations were found between the cells isolated from blood vessels, bronchi, and visceral organs. Furthermore, pervasive differences were noted within the visceral organ subgroups that appear to reflect the distinct molecular pathways essential for organogenesis as well as those involved in organ-specific contractile and physiological properties. Finally, we sought to understand how this diversity may contribute to SMC-involving pathology. We found that a gene expression signature of the responses of vascular SMCs to serum exposure is associated with a significantly poorer prognosis in human cancers, potentially linking vascular injury response to tumor progression.     

Heteroplasmic mutation of mitochondrial DNA D-loop and 4977-bp deletion in human cancer cells during mitochondrial DNA depletion

Somatic mutations in mitochondrial DNA (mtDNA) have been demonstrated in various human cancers. Many cancers have high frequently of mtDNA with homoplasmic point mutations, and carry less frequently of mtDNA with large-scale deletions as compared with corresponding non-cancerous tissue. Moreover, most cancers harbor a decreased copy number of mtDNA than their corresponding non-cancerous tissue. However, it is unclear whether the process of decreasing in mtDNA content would be involved in an increase in the heteroplasmic level of somatic mtDNA point mutation, and/or involved in a decrease in the proportion of mtDNA with large-scale deletion in cancer cells. In this study, we provided evidence that the heteroplasmic levels of variations in cytidine number in np 303-309 poly C tract of mtDNA in three colon cancer cells were not changed during an ethidium bromide-induced mtDNA depleting process. In the mtDNA depleting process, the proportions of mtDNA with 4977-bp deletion in cybrid cells were not significantly altered. These results suggest that the decreasing process of mtDNA copy number per se may neither contribute to the shift of homoplasmic/heteroplasmic state of point mutation in mtDNA nor to the decrease in proportion of mtDNA with large-scale deletions in cancer cells. Mitochondrial genome instability and reduced mtDNA copy number may independently occur in human cancer.     

利用SRAP和SSR分子标记检测分析29份棉花种质遗传完整性

利用SRAP和SSR分子标记检测29份棉花种质遗传完整性。结果表明,无论每一份不同更新发芽率水平繁殖后代的种质之间,还是每一份不同繁殖世代数种质之间,其等位基因频率差异不显著,也没有检测到稀有等位基因缺失的情况。本试验表明不同更新发芽率水平和繁殖世代数差异没有对棉花这种常异花授粉作物种质遗传完整性变化产生影响。     

Studies on the influence of phasins on accumulation and degradation of PHB and nanostructure of PHB granules in ralstonia eutropha H16

Phasins play an important role in the formation of poly(3-hydroxybutyrate) [PHB] granules and affect their size and number in the cells. Recent studies on the PHB granule proteome and analysis of the complete genomic DNA sequence of Ralstonia eutropha H16 have identified three homologues of the phasin protein PhaP1. In this study, mutants of R. eutropha deficient in the expression of the phasin genes phaP1, phaP2, phaP3, phaP4, phaP12, phaP123, and phaP1234 were examined by gas chromatography. In addition, the nanostructures of the PHB granules of the wild-type and of the mutants were imaged by atomic force microscopy (AFM), and the molecular masses of the accumulated PHB were analyzed by gel permeation chromatography. For this, cells were cultivated under conditions permissive for accumulation of PHB and were then cultivated under conditions permissive for degradation of PHB. Mutants deficient in the expression of phaP2, phaP3, or phaP4 genes mobilized the stored PHB only slowly like the wild-type, whereas degradation occurred much earlier and faster in the phaP1 single mutant as well as in all multiple mutants defective in the phaP1 gene plus one or more other phasin genes. This indicated that the presence of the major phasin PhaP1 on the granule surface is important for PHB degradation and that this phasin is therefore of particular relevance for PHB accumulation. It was also shown that the molecular weights of the accumulated PHB were identical in all examined strains; phasins have therefore no influence on the molecular weight of PHB. The AFM images obtained in this study showed that the PHB granules of R. eutropha H16 form a single interconnected system inside the wild-type cells.     

Structural basis of functional cooperation of Tim15/Zim17 with yeast mitochondrial Hsp70

Mitochondrial heat-shock protein 70 (mtHsp70) and its partner proteins drive protein import into the matrix. Tim15/Zim17/Hep1 is a mtHsp70 partner protein on the matrix side of the inner mitochondrial membrane. We determined the nuclear magnetic resonance (NMR) structure of the core domain of Tim15. On the basis of the NMR structure, we created Tim15 mutants and tested their ability to complement the functional defects of Tim15 depletion and to suppress self-aggregation of mtHsp70 in vivo. A pair of basic residues, Arg 106 and His 107, conserved Asp 111 and flexible loop 133-137, and were important (Arg 106-His 107 pair and Asp 111) or partly important (the loop 133-137) for yeast cell growth, mitochondrial protein import and the suppression of mtHsp70 aggregation. Therefore, the function of Tim15 in yeast cell growth is well correlated with its ability to suppress mtHsp70 aggregation, although it is still unknown whether inhibition of mtHsp70 aggregation is the primary function of Tim15.     

Mechanism of alcohol‐enhanced lucigenin chemiluminescence in alkaline solution

The chemiluminescence (CL) of lucigenin (Luc²⁺) can be enhanced by different alcohols in alkaline solution. The effect of different fatty alcohols on the CL of lucigenin was related to the carbon chain length and the number of hydroxyl groups. Glycerol provides the greatest enhancement. UV/Vis absorption spectra and fluorescence spectra showed that N‐methylacridone (NMA) was produced in the CL reaction in the presence of different alcohols. The peak of the CL spectrum was located at 470 nm in all cases, indicating that the luminophore was always the excited‐state NMA. The quenching of lucigenin CL by superoxide dismutase (SOD) and the electron spin resonance (ESR) results with the spin trap of 5,5‐dimethyl‐1‐pyrroline N‐oxide (DMPO) demonstrated that superoxide anions (O₂^?–) were generated from dissolved oxygen in the CL reaction and that glycerol and dihydroxyacetone (DHA) can promote O₂^?? production by the reduction of dissolved oxygen in alkaline solution. It was assumed that the enhancement provided by different alcohols was related to the solvent effect and reducing capacity. Glycerol and DHA can also reduce Luc²⁺ into lucigenin cation radicals (Luc^?+), which react with O₂^?? to produce CL, and glycerol can slowly transform into DHA, which is oxidized quickly in alkaline solution. Copyright © 2015 John Wiley & Sons, Ltd.