Lymphocytes and MHC class II positive cells in the female rabbit reproductive tract before and after ovulation

In this study, we identified lymphocytes and MHC class II positive (MHC-II+) cells in the reproductive tract of female rabbits both before and after ovulation. CD43+ T cells were frequently present in the mucosa of the oviduct, cervix, and vagina, but far fewer positive cells were seen in the endometrium. The induction of ovulation did not change the cell density in these regions. KEN-5+ T cells and MHC-II+ cells were also frequently seen in the mucosa of the oviduct, cervix, and vagina both before and after ovulation. However, in the uterus, there were very few positive cells before ovulation, but the number increased dramatically after ovulation. Associated with the increase of KEN-5+ T cells, IL-2 mRNA expression in the uterus also increased after ovulation, suggesting that the uterus experienced an increase of T-cell activation. IgM- and IgA-positive B cells were not commonly seen in the reproductive tract and the induction of ovulation did not alter this. Our results suggest that the reproductive tract of female rabbits has the capacity to mount an immune response and that the immune cell distribution of the rabbit reproductive tract has some distinctive features compared with that found in other species.     

Pathological cell-cell interactions elicited by a neuropathogenic form of mutant Huntingtin contribute to cortical pathogenesis in HD mice

Expanded polyglutamine (polyQ) proteins in Huntington's disease (HD) as well as other polyQ disorders are known to elicit a variety of intracellular toxicities, but it remains unclear whether polyQ proteins can elicit pathological cell-cell interactions which are critical to disease pathogenesis. To test this possibility, we have created conditional HD mice expressing a neuropathogenic form of mutant huntingtin (mhtt-exon1) in discrete neuronal populations. We show that mhtt aggregation is a cell-autonomous process. However, progressive motor deficits and cortical neuropathology are only observed when mhtt expression is in multiple neuronal types, including cortical interneurons, but not when mhtt expression is restricted to cortical pyramidal neurons. We further demonstrate an early deficit in cortical inhibition, suggesting that pathological interactions between interneurons and pyramidal neurons may contribute to the cortical manifestation of HD. Our study provides genetic evidence that pathological cell-cell interactions elicited by neuropathogenic forms of mhtt can critically contribute to cortical pathogenesis in a HD mouse model.     

New antitubulin derivatives in the combretastatin A4 series: synthesis and biological evaluation

Two series of combretastatin A4 derivatives (acrylamide=carboxamide and carbamate) were synthesized in order to improve the water solubility and stabilize the cis-configuration of the double bond. Their cytotoxic effects were evaluated against MCF-7, KB-3-1 and IGROV human cancer cell lines, as well as their inhibitory activity on tubulin polymerization. Results were compared to those of carboxamide 1, chosen as reference. Potent inhibitions were observed on both tests in the carboxamide series, particularly for compound 4d bearing a fluorine group in replacement of the 3-hydroxyl of CA4. In contrast, most of the carbamates were either inactive or displayed only moderate cytotoxicities. Interestingly, a submicromolar IC(50) was measured on MCF-7 cells for 6g, although this compound was totally devoid of antitubulin activity.     

Two novel series of allocolchicinoids with modified seven membered B-rings: design, synthesis, inhibition of tubulin assembly and cytotoxicity

Two new attractive series of allocolchicinoids were designed as inhibitors of tubulin assembly using the potent ketone 4 and the tetracyclic, pyrazole annulated NCME variant 7 (NCME = N-acetyl colchinol-O-methylether (2)) as lead structures. The first group of inhibitors of type 6 with novel oxepine and azepine B-ring structures belongs to the NCME-series and was synthesized via a multistep total synthesis starting from simple and cheap 3-methoxybenzaldehyde (12) and 3,4,5-trimethoxybenzaldehyde (13). Biaryl-coupling of the starting materials 12 and 13 was accomplished via Ziegler-Ullmann-reaction to furnish the biphenyl 11 equipped with two carbaldehyde functions. The subsequent Cannizzaro reaction of this dicarbaldehyde 11 proceeded with high regioselectivity to yield almost exclusively the key compound, the hydroxymethyl carboxylic acid 9. Ring closure to the o,o'-bridged biphenyls was accomplished by two routes: on the one hand, treatment of 9 with aqueous hydrochloric acid yielded the lactone 15. On the other hand, a four step sequence starting from the isomeric mixture 9/10 furnished the constitutionally isomeric lactams 23 and 24; these could be converted to the corresponding thiolactams 25 and 26 and to the tetrazole annulated NCME-type derivatives 27 and 28. The second series of bioactive compounds are congeners of allocolchicine (3). The well known desacetyl allocolchicine (29) was easily oxidized to the oxime 30, which was further transformed to the corresponding ketone 31. This served as key precursor for the syntheses of various tetracyclic allocolchicine modifications 33-36 annulated with a pyrazole, isoxazole, pyrimidine or 2-aminopyrimidine heterocycle, respectively. Unexpectedly, all the NCME-variants with a substituent in position 7 like in NCME (2) inhibited the tubulin assembly only moderately. In contrast, the new series of allocolchicine modifications proved to be highly potent antimicrotubule agents. Inhibition of tubulin assembly occurred at lower concentrations compared to those measured for the reference colchicine (1). Surprisingly, these promising results could not be confirmed in the cytotoxicity tests against the human MCF-7 breast cancer cell line, where an unexpected loss of effectiveness compared to the corresponding NCME-derivatives was observed.     

Systematic high-yield production of human secreted proteins in Escherichia coli

Human secreted proteins play a very important role in signal transduction. In order to study all potential secreted proteins identified from the human genome sequence, systematic production of large amounts of biologically active secreted proteins is a prerequisite. We selected 25 novel genes as a trial case for establishing a reliable expression system to produce active human secreted proteins in Escherichia coli. Expression of proteins with or without signal peptides was examined and compared in E. coli strains. The results indicated that deletion of signal peptides, to a certain extent, can improve the expression of these proteins and their solubilities. More importantly, under expression conditions such as induction temperature, N-terminus fusion peptides need to be optimized in order to express adequate amounts of soluble proteins. These recombinant proteins were characterized as well-folded proteins. This system enables us to rapidly obtain soluble and highly purified human secreted proteins for further functional studies.     

Target syntheses of saturated Keggin polyoxometalate-based extended solids

By the approach of target synthesis, three infinitely extended hybrid compounds based on the saturated Keggin polyoxoanions have been synthesized under hydrothermal conditions: , and (phen = 1,10-phenanthroline, trea = triethylamine). The isostructural compounds 1 and 2 belong to the monoclinic space group P2₁/c and both contain neutral 2D layers and discrete polyoxometalate clusters decorated by transitional metal complexes. They represent an important example of the family of intercalated solids, in which both the 2D layers and the intercalated molecules are polyoxometalates with covalently linked transitional metal complex fragments. Compound 3, crystallizing in the monoclinic space group C2/c, consists of 1D zigzag chains constructed from alternating polyoxoanions and [Ni(phen)₂]²⁺ fragments. More interestingly, these three compounds are constructed directly from saturated polyoxometalates, in which the intact skeletons of Keggin clusters are maintained under hydrothermal conditions. Variable-temperature magnetic susceptibility measurements of compounds 1 and 2 reveal the feature of antiferromagnetic exchange interaction in these compounds.     

Molecular cloning and characterization of a novel human gene containing 4 ankyrin repeat domains

Ankyrin repeat, one of the most important protein motifs, plays a wide variety of roles in protein-protein interactions and in the signal pathways. Via large-scale sequencing, a novel 941-bp gene was isolated from an 18-week old human fetal brain cDNA library. It encodes a putative protein of 158 amino acid residues with four conserved ankyrin repeat domains. It displays a high degree of homology with rat low-density lipoprotein receptor-related protein 2-binding protein (Lrp2bp), and was therefore was named hLrp2bp (human Lrp2bp). The hLrp2bp gene was located in chromosome 4q35 and the conserved ankyrin repeat domains were located between amino acid residues 10 and 116. RT-PCR revealed that hLrp2bp was mainly expressed in the human testis, small intestine, colon and blood leukocytes, and in human pancreatic adenocarcinoma cells. A HEK293 cell was transfected with the ORF of hLrp2bp, and analyses showed that the protein was distributed both in the cytoplasm and nucleus.     

Rapid spontaneous accessibility of nucleosomal DNA

DNA wrapped in nucleosomes is sterically occluded, creating obstacles for proteins that must bind it. How proteins gain access to DNA buried inside nucleosomes is not known. Here we report measurements of the rates of spontaneous nucleosome conformational changes in which a stretch of DNA transiently unwraps off the histone surface, starting from one end of the nucleosome, and then rewraps. The rates are rapid. Nucleosomal DNA remains fully wrapped for only approximately 250 ms before spontaneously unwrapping; unwrapped DNA rewraps within approximately 10-50 ms. Spontaneous unwrapping of nucleosomal DNA allows any protein rapid access even to buried stretches of the DNA. Our results explain how remodeling factors can be recruited to particular nucleosomes on a biologically relevant timescale, and they imply that the major impediment to entry of RNA polymerase into a nucleosome is rewrapping of nucleosomal DNA, not unwrapping.     

Differentiation of insulin-producing cells from human neural progenitor cells

BackgroundSuccess in islet-transplantation-based therapies for type 1 diabetes, coupled with a worldwide shortage of transplant-ready islets, has motivated efforts to develop renewable sources of islet-replacement tissue. Islets and neurons share features, including common developmental programs, and in some species brain neurons are the principal source of systemic insulin.Methods and FindingsHere we show that brain-derived human neural progenitor cells, exposed to a series of signals that regulate in vivo pancreatic islet development, form clusters of glucose-responsive insulin-producing cells (IPCs). During in vitro differentiation of neural progenitor cells with this novel method, genes encoding essential known in vivo regulators of pancreatic islet development were expressed. Following transplantation into immunocompromised mice, IPCs released insulin C-peptide upon glucose challenge, remained differentiated, and did not form detectable tumors.ConclusionProduction of IPCs solely through extracellular factor modulation in the absence of genetic manipulations may promote strategies to derive transplantable islet-replacement tissues from human neural progenitor cells and other types of multipotent human stem cells.