Neuron-specific enolase-cre mouse line with cre activity in specific neuronal populations

To establish genetic tools for conditional gene deletion in mouse neurons, we generated two independent neuron-specific enolase (Nse)-cre transgenic lines. The transgenic line termed Nse-cre(CK1) showed cre activity in most neuronal regions in the nervous system, while the Nse-cre(CK2) line exhibited a unique cre activity that has not been reported in other cre transgenic lines. Nse-cre(CK2) cre activity was detectable from embryogenesis and mostly restricted to neuronal regions. In postnatal brain, the Nse-cre(CK2) line exhibited cre activity limited to differentiated neurons in the cerebral cortex and hippocampus. Cre activity was assayed in several internal organs and sporadic activity was limited to the kidney and testis. We conclude that these cre lines will be useful for studying loss of gene function in specific neuronal populations.     

Expression, purification and the 1.8 angstroms resolution crystal structure of human neuron specific enolase

Human neuron-specific enolase (NSE) or isozyme gamma has been expressed with a C-terminal His-tag in Escherichia coli. The enzyme has been purified, crystallized and its crystal structure determined. In the crystals the enzyme forms the asymmetric complex NSE x Mg2 x SO4/NSE x Mg x Cl, where "/" separates the dimer subunits. The subunit that contains the sulfate (or phosphate) ion and two magnesium ions is in the closed conformation observed in enolase complexes with the substrate or its analogues; the other subunit is in the open conformation observed in enolase subunits without bound substrate or analogues. This indicates negative cooperativity for ligand binding between subunits. Electrostatic charge differences between isozymes alpha and gamma, -19 at physiological pH, are concentrated in the regions of the molecular surface that are negatively charged in alpha, i.e. surface areas negatively charged in alpha are more negatively charged in gamma, while areas that are neutral or positively charged tend to be charge-conserved.     

Structural basis for catalytic racemization and substrate specificity of an N-acylamino acid racemase homologue from Deinococcus radiodurans

N-acylamino acid racemase (NAAAR) catalyzes the racemization of N-acylamino acids and can be used in concert with an aminoacylase to produce enantiopure alpha-amino acids, a process that has potential industrial applications. Here we have cloned and characterized an NAAAR homologue from a radiation-resistant ancient bacterium, Deinococcus radiodurans. The expressed NAAAR racemized various substrates at an optimal temperature of 60 degrees C and had Km values of 24.8 mM and 12.3 mM for N-acetyl-D-methionine and N-acetyl-L-methionine, respectively. The crystal structure of NAAAR was solved to 1.3 A resolution using multiwavelength anomalous dispersion (MAD) methods. The structure consists of a homooctamer in which each subunit has an architecture characteristic of enolases with a capping domain and a (beta/alpha)7 beta barrel domain. The NAAAR.Mg2+ and NAAAR.N-acetyl-L-glutamine.Mg2+ structures were also determined, allowing us to define the Lys170-Asp195-Glu220-Asp245-Lys269 framework for catalyzing 1,1-proton exchange of N-acylamino acids. Four subsites enclosing the substrate are identified: catalytic site, metal-binding site, side-chain-binding region, and a flexible lid region. The high conservation of catalytic and metal-binding sites in different enolases reflects the essentiality of a common catalytic platform, allowing these enzymes to robustly abstract alpha-protons of various carboxylate substrates efficiently. The other subsites involved in substrate recognition are less conserved, suggesting that divergent evolution has led to functionally distinct enzymes.     

Hexose metabolism in pancreatic islets: phosphoglycerate 2,3-mutase and enolase activities in rat islets

Rat islet homogenates display both phosphoglycerate 2,3-mutase and enolase activities. When phosphoglycerate 2,3-mutase is activated by 2,3-diphosphoglycerate, the reaction velocity becomes close to that of enolase. The islet content in 2,3-diphosphoglycerate is sufficiently high to allow virtually full activation of phosphoglycerate 2,3-mutase.     

TnT-Hs和NSE在手足口病患儿中的表达水平及临床意义

目的：探讨TnT-Hs和NSE水平在手足口病患儿中的表达及临床意义。方法：选择我院2012年6月-2013年6月确诊为手足口病的住院患儿68例作为观察组,选择同期入院健康体检的68例正常儿童作为对照组,对比两组心肌钙蛋白T（TnT—Hs）与血清神经元特异性烯醇化酶（NSE）水平;并对观察组EV71阳性患儿与阴性患儿TnT-Hs与NSE水平进行比较。结果：①相比健康对照组,观察组TnT-Hs与NSE水平均较高,差异有统计学意义（P〈0．01）。②EV71阳性患儿46例,阴性患儿22例,阳性患儿相比阴性患儿TnT-Hs与NSE水平较高,差异均有统计学意义（P〈0．05）。结论：Tn—T-Hs和NSE水平可反映手足口病患儿病情进展变化,其可作为早期预测手足口病患儿心肌损害及脑损伤的依据及重症病例的预警指标。     

NSE 和NGF 在颅脑损伤后血清中含量变化及临床意义

创伤性颅脑损伤后外周血清中神经元特异性烯醇化酶(NSE)和神经生长因子(NGF)含量呈动态变化,在颅脑损伤(尤其是重型颅脑损伤)早期即可出现表达增加,其中NSE含量与颅脑损伤程度呈正相关,而NGF在颅脑损伤后的神经修复、再生和神经元保护等机制中起重要作用,其在血清中含量变化的临床意义明显不同。两者在血清中含量变化对于颅脑损伤后病情、治疗及预后评估有重要的作用,是颅脑损伤后评估病情、进行治疗的重要指标,因此监测血清中NSE及NGF的变化,可以为更准确判断病情、评估预后,并为临床治疗提供依据。本文就其在颅脑损伤患者血清中的含量变化及临床意义作以简要综述。     

The Raf/MEK/extracellular signal-regulated kinase 1/2 pathway can mediate growth inhibitory and differentiation signaling via androgen receptor downregulation in prostate cancer cells

Upregulated ERK1/2 activity is correlated with androgen receptor (AR) downregulation in certain prostate cancer (PCa) that exhibits androgen deprivation-induced neuroendocrine differentiation, but its functional relevance requires elucidation. We found that sustained ERK1/2 activation using active Raf or MEK1/2 mutants is sufficient to induce AR downregulation at mRNA and protein levels in LNCaP. Downregulation of AR protein, but not mRNA, was blocked by proteasome inhibitors, MG132 and bortezomib, indicating that the pathway regulation is mediated at multiple points. Ectopic expression of a constitutively active AR inhibited Raf/MEK/ERK-mediated regulation of the differentiation markers, neuron-specific enolase and neutral endopeptidase, and the cyclin-dependent kinase inhibitors, p16^INK4A and p21^CIP1, but not Rb phosphorylation and E2F1 expression, indicating that AR has a specific role in the pathway-mediated differentiation and growth inhibitory signaling. However, despite the sufficient role of Raf/MEK/ERK, its inhibition using U0126 or ERK1/2 knockdown could not block androgen deprivation-induced AR downregulation in an LNCaP neuroendocrine differentiation model, suggesting that additional signaling pathways are involved in the regulation. We additionally report that sustained Raf/MEK/ERK activity can downregulate full length as well as hormone binding domain-deficient AR isoforms in androgen-refractory C4-2 and CWR22Rv1, but not in LAPC4 and MDA-PCa-2b. Our study demonstrates a novel role of the Raf/MEK/ERK pathway in regulating AR expression in certain PCa types and provides an insight into PCa responses to its aberrant activation.     

Doublecortin is expressed in articular chondrocytes

Articular cartilage and cartilage in the embryonic cartilaginous anlagen and growth plates are both hyaline cartilages. In this study, we found that doublecortin (DCX) was expressed in articular chondrocytes but not in chondrocytes from the cartilaginous anlagen or growth plates. DCX was expressed by the cells in the chondrogenous layers but not intermediate layer of joint interzone. Furthermore, the synovium and cruciate ligaments were DCX-negative. DCX-positive chondrocytes were very rare in tissue engineered cartilage derived from in vitro pellet culture of rat chondrosarcoma, ATDC5, and C3H10T1/2 cells. However, the new hyaline cartilage formed in rabbit knee defect contained mostly DCX-positive chondrocytes. Our results demonstrate that DCX can be used as a marker to distinguish articular chondrocytes from other chondrocytes and to evaluate the quality of tissue engineered or regenerated cartilage in terms of their "articular" or "non-articular" nature.     

Cloning and expression of neuron-specific enolase in the corpus luteum of dairy goats

Neuron-specific enolase (NSE) is the key molecular marker for diffuse neuroendocrine system (DNES) cells, its expression in the pregnant corpus luteum (CL) of dairy goats was studied by the immunofluorescence method and the ultra structural characteristics of luteal cells were detected by the electron microscopy to identify the existence of DNES cells in the pregnant CL of dairy goats. Besides, the coding sequence of dairy goats NSE gene was cloned and its biological information was analyzed. Results revealed that NSE immunopositive cells exhibited widespread cytoplasmic staining throughout the whole pregnant CL. In addition, these cells showed typical characteristics of DNES cells in the electron microscopy. These results suggested that many DNES cells exist in the pregnant CL of dairy goats. Meanwhile, we identified the coding sequence of dairy goats NSE (GenBank Accession No. JN887466). Its nucleotide sequence homology was found to be 97.9%, 89.3%, 90% and 92.6%, respectively, compared with that of Bos taurus, Rattus norvegicus, Mus musculus and Homo sapiens, while the amino acid sequence homology was 99.1%, 97%, 97.2% and 98.2% respectively. These results first showed that the functional amino acids coded by the NSE gene were highly conserved in Caprine, B. taurus, R. norvegicus, M. musculus and H. sapiens. It was implied that the gene NSE in dairy goats had close homology to that of NSE of other species. Our findings demonstrated the possible existence of DNES cells in pregnant CL, providing new clue for further understanding of interactions between the neuroendocrine and reproductive systems. Characterization of gene sequence of dairy goats NSE will enable us to synthesize interference RNA for further study on the role of NSE on the formation, function and apoptosis of pregnant CL in dairy goats.     

Safrole oxide induced neuronal differentiation of rat bone-marrow mesenchymal stem cells by elevating Hsp70

In a previous study, we found that at low concentrations, safrole oxide (SFO) could induce vascular endothelial cell (VEC) transdifferentiation into neuron-like cells; however, whether SFO could induce bone-marrow mesenchymal stem cell (BMSC) neural differentiation was unknown. Here, we found that SFO could effectively induce BMSC neural differentiation in the presence of serum and fibroblast growth factor 2 and did not affect cell viability at low concentrations. The levels of neuron-specific enolase and neurofilament-L were increased greatly, but that of glial fibrillary acidic protein was absent with SFO treatment for 48 h. Furthermore, SFO could increase the level of heat shock protein 70 (Hsp70), an important factor in neuronal differentiation. Knockdown of Hsp70 by its small interfering RNA blocked SFO-induced BMSC differentiation. Thus, SFO is a novel inducer of BMSC differentiation to neuron-like cells and Hsp70 is implicated in the differentiation process. We provide a new tool for obtaining neuron-like cells from BMSCs and for further investigating the new effect of Hsp70 on BMSC neuronal differentiation.