Switching from bone marrow-derived neurons to epithelial cells through dedifferentiation and translineage redifferentiation

While the ability of stem cells to switch lineages has been suggested, the route(s) through which this may happen is unclear. To date, the best characterized adult stem cell population considered to possess transdifferentiation capacity is BM-MSCs (bone marrow mesenchymal stem cells). We investigated whether BM-MSCs that had terminally differentiated into the neural or epithelial lineage could be induced to transdifferentiate into the other phenotype in vitro. Our results reveal that neuronal phenotypic cells derived from adult rat bone marrow cells can be switched to epithelial phenotypic cells, or vice versa, by culture manipulation allowing the differentiated cells to go through, first, dedifferentiation and then redifferentiation to another phenotype. Direct transdifferentiation from differentiated neuronal or epithelial phenotype to the other differentiated phenotype cannot be observed even when appropriate culture conditions are provided. Thus, dedifferentiation appears to be a prerequisite for changing fate and differentiating into a different lineage from a differentiated cell population.     

Design, synthesis and bioevaluation of dihydropyrazolo[3,4-b]pyridine and benzo[4,5]imidazo[1,2-a]pyrimidine compounds as dual KSP and Aurora-A kinase inhibitors for anti-cancer agents

Four series of dihydropyrazolo[3,4-b]pyridines and benzo[4,5]imidazo[1,2-a]pyrimidines were designed and synthesized as dual KSP and Aurora-A kinase inhibitors for anti-cancer agents by introducing some fragments of Aurora-A kinase inhibitors into our KSP inhibitor CPUYL064. A total of 19 target compounds were evaluated by two related enzyme inhibition assays and a cytotoxicity assay in vitro. The results showed that some target compounds could inhibit both enzymes, and several of them showed significant inhibition activity against HCT116 cell line. Despite showing moderate KSP and Aurora-A kinase inhibition, the lead compounds 6a and 6e displayed significant cytotoxic activity in the micromolar range, especially against the HCT116 cell line and HepG2 cell line. The results may be useful for developing a new class of inhibitors having a dual function, KSP inhibition and Aurora-A kinase inhibition, for the treatment of cancer.     

A high-throughput, homogeneous, fluorescence polarization assay for inhibitors of hedgehog protein autoprocessing

Hedgehog (Hh) signaling plays an important role in embryonic patterning and adult stem cell renewal but has recently been found also to be involved in certain stem cell cancers. One of the first steps in Hh signaling is the autoprocessing of Hh protein, in which the C-terminal domain (Hh-C) catalyzes a cholesterol-dependent autocleavage reaction that leads to the production of the cholesterol ester of the N-terminal Hh domain (Hh-N), thereby yielding a signaling molecule that activates the Hh pathway by binding to the Patched receptor. This article describes an in vitro, homogeneous assay system that measures changes in fluorescence polarization that accompany the cholesterol-dependent autocleavage of Hh protein. The assay system makes use of a modified Hh protein in which Hh-N, which is not essential for autocleavage, is replaced by a 25-residue peptide containing a tetracysteine motif, complexed with a bisarsenical fluorophore. The assay is quite robust and easily adapted to high-throughput screening in 384-well plates with Z' factors above 0.8. It has been used to screen the National Institutes of Health Clinical Collection, which has led to the identification of 2 compounds that inhibit the cholesterol-dependent autocleavage of Hh protein at micromolar concentrations.     

Census of orthologous genes and self-organizing maps of biologically relevant transcriptional patterns in chickens (Gallus gallus)

The launch of large-scale chicken expressed sequence tags (EST) projects has placed the chicken in the lead for the number of EST sequences in agriculturally important animals. More than 451,000 chicken ESTs derived from over 158 libraries have been deposited in the NCBI dbEST database as of December 2003. But how many genes these ESTs represent and how they are expressed in different chicken tissues/organs remain undetermined. In the present research, we developed a human gene-based strategy for census of chicken orthologous genes and identification of their expression patterns. Among 34,157 human coding genes used in the study, BLAST analysis revealed that 11,066 genes provisionally matched 248,628 chicken ESTs. Based on the average EST abundance of the orthologous genes, the current public repository of chicken ESTs could represent 20,000 provisional genes. Analysis of gene expression in 14 single tissues/organs showed that approximately 15% of genes were expressed exclusively in single tissue/organ whereas the remaining 85% of genes were co-expressed in two or more tissues/organs. A majority (91.15%) of genes expressed in chicken embryos were also expressed at post-hatch stages, indicating that most genes activated in chicken embryos could serve housekeeping functions. Self-organizing maps (SOM) analysis organized 8807 provisional genes in selected chicken tissues into 98 clusters with each cluster being indicative of common regulatory factors and pathways. A total of 969 provisional orthologous genes were identified as preferentially expressed genes (PEGs) in various chicken tissues/organs (LOD>3.0). No doubt, the present study on gene expression patterns will provide insight into dynamics of metabolic pathways and tissue/organ programming and reprogramming in chickens.     

Relationship between Serum Testosterone, Dominance and Mating Success in Père David's Deer Stags

We conducted an experiment in the Beijing Milu Park to study the social behavior of male Père David's deer, and related social behavior to social position and serum testosterone level of the stags during rut. We classified the stags into three rank classes according to their rutting behavior: ‘harem master’, ‘challenger’ and ‘bachelor’. We monitored the behaviors of four ‘harem masters’, five ‘challengers’ and five ‘bachelors’, and analyzed serum testosterone levels in blood samples of those 14 stags using radioimmunoassay. We defined the effectiveness value, E = A/T, to assess the effectiveness of herding or mating attempts made by stags (‘T’ represents the frequency of herding or mating attempts made by a stag and ‘A’ represents the frequency of herding or mating attempts accepted by hinds). We found that: (1) the ‘harem masters’ and the ‘challengers’ displayed more frequent rut and locomotive behaviors but fewer ingestion behaviors than the ‘bachelors’; (2) serum testosterone levels in the ‘harem masters’ and the ‘challengers’ were higher than that in the ‘bachelors’; (3) effectiveness value of herding attempts differed significantly between the three types of stags, being highest in the ‘harem masters’ and the lowest in the ‘bachelors’; and (4) effectiveness value of mating attempts was significantly greater for the ‘harem masters’ than for the ‘challengers’. We conclude that: (1) reproductive behavior of the Père David's deer stags is strongly associated with social rank; (2) social roles of Père David's deer stags during the rut are related to the testosterone secretion; and (3) rank class affects the mating opportunity of the stags.     

N—acetylserotonin对肝缺血再灌注小鼠氧化应激损伤的保护作用

目的探讨NAS对肝缺血再灌注所诱导的脂质过氧化损伤产生的保护作用。方法采用夹闭肝蒂法30min、再灌注6h制作肝缺血再灌注模型,冰冻切片,HE染色,光学显微镜下观察肝细胞形态结构的变化;比色法检测损伤后血清中谷丙转氨酶（ALT）水平及肝组织中超氧化物歧化酶（SOD）、丙二醛（MDA）、谷胱甘肽过氧化物酶（GSH—Px）的含量。结果夹闭肝蒂30min、再灌注6h后,肝小叶结构紊乱、肝血窦淤血,其间有白细胞浸润、肝细胞出现变性、坏死;血清中ALT水平升高,肝组织中s0D和GSH—Px的含量降低,MDA升高;NAS可减少缺血再灌注后血清ALT的释放,使肝组织中SOD和GSHPx的含量升高,MDA的含量降低;NAS＋Luz可逆转NAS的这一作用。结论NAS对肝缺血再灌注小鼠的氧化应激损伤具有保护作用。     

Screening proteins interacting with VpPR10.1 of Chinese wild grapevine using the yeast two-hybrid system

Among the 17 plant pathogenesis-related (PR) protein families, only PR10 family is intracellular and cytosolic. PR proteins are expressed in response to pathogen challenge and abiotic stresses in higher plants. However, the molecular mechanisms of their actions remain poorly understood. In a previous work, we isolated a PR10 gene from Erysiphe necator-resistant Chinese wild Vitis sp. (Baihe-35-1) and it was designated as VpPR10.1. In this study, yeast two-hybrid method was used to screen proteins interacting with VpPR10.1 proteins. Twenty-one ESTs were isolated and sequenced. All sequences were compared using BLASTx to identify presumptive orthologs. Several proteins associated with VpPR10.1 protein were screened, including CNR8, UFGT6, HSP, DEAD-box, Trx h2, Grx C9 and GLOX. These proteins are closely related to defensive action of plants against pathogens and abiotic stresses. Our results reveal that VpPR10.1 gene may be involved in hormone signaling, programmed cell death and defense responses of grapevine.     

Structure and function of the CBL–CIPK Ca2+-decoding system in plant calcium signaling

Calcium is a crucial messenger in many growth and developmental processes in plants. The central mechanism governing how plant cells perceive and respond to environmental stimuli is calcium signal transduction, a process through which cellular calcium signals are recognized, decoded, and transmitted to elicit downstream responses. In the initial decoding of calcium signals, Ca²⁺ sensor proteins that bind Ca²⁺ and activate downstream signaling components are implicated, thereby regulating specific physiological and biochemical processes. After calcineurin B-like proteins (CBLs) sense these Ca²⁺ signatures, these proteins interact selectively with CBL-interacting protein kinases (CIPKs), thereby forming CBL/CIPK complexes, which are involved in decoding calcium signals. Therefore, specificity, diversity, and complexity are the main characteristics of the CBL-CIPK signaling system. However, additional CBLs, CIPKs, and CBL/CIPK complexes remain to be identified in plants, and the specific functions of their abiotic and biotic stress signaling will need to be further dissected. Therefore, a much-needed synthesis of recent findings is important to further the study of CBL-CIPK signaling systems. Here, we review the structure of CBLs and CIPKs, discuss the current knowledge of CBL–CIPK pathways that decode calcium signals in Arabidopsis, and link plant responses to a variety of environmental stresses with specific CBL/CIPK complexes. This will provide a foundation for future research on genetically engineered resistant plants with enhanced tolerance to various environmental stresses.