Faculty Bibliography

As most of the available depigmenting agents exhibit only modest activity and some exhibit toxicities that lead to adverse side effects after long-term usage, there remains a need for novel depigmenting agents. Chemical genetic screening was performed on cultured melanocytes to identify novel depigmenting compounds. By screening a tagged-triazine library, we identified four compounds, TGH11, TGD10, TGD39 and TGJ29, as potent pigmentation inhibitors with IC50 values in the range of 10 microM. These newly identified depigmenting compounds were found to function as reversible inhibitors of tyrosinase, the key enzyme involved in melanin synthesis. Tyrosinase was further confirmed as the cellular target of these compounds by affinity chromatography. Kinetic data suggest that all four compounds act as competitive inhibitors of tyrosinase, most likely competing with L-3,4-dihydroxyphenylalanine (L-DOPA) for binding to the DOPA-binding site of the enzyme. No effect on levels of tyrosinase protein, processing or trafficking was observed upon treatment of melanocytes with these compounds. Cytotoxicity was not observed with these compounds at concentrations up to 20 muM. Our data suggest that TGH11, TGD10, TGD39 and TGJ29 are novel potent tyrosinase inhibitors with potential beneficial effects in the treatment of cutaneous hyperpigmentation

Since cytokines and chemokines are important actors in rheumatoid arthritis (RA), the aim of this study was to compare the gene expression profiles in cultured fibroblast-like synoviocytes (FLS) obtained from patients with either RA, or osteoarthritis (OA), focusing our analysis on genes for cytokines and chemokines, and their respective receptors. Gene expression in cultured FLS (third passage) from eight patients with RA (RA-FLS) were compared with gene expression in cultured FLS from nine patients with OA (OA-FLS) using Affymetrix Human Genome U133 Plus 2.0 Array microarray, allowing analysis of over 54,000 transcripts. Among the 171 genes studied (241 probes), limiting the selection of differentially expressed genes to a significant value (p < 0.05), and a differential ratio of expression > 1.6, only four genes, namely IL-32, CCL2, PF4F1 and GDF10 were found to be differentially expressed. Out of these four genes, only higher expression of CCL2 has been reported previously in RA. The newly described cytokine IL-32 was the most prominently differentially expressed gene in the present study, with higher expression in RA-FLS than in OA-FLS (p < 0.0073). IL-32 might have a previously unidentified pivotal role in RA.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by destruction of cartilage and bone. The destructive lesions result from both immune responses and non-antigen-specific inflammatory processes. Little is known about the primary cause of RA. Although the primacy of T-cell-related events early in the disease remains debated, strong evidence indicates that autoantigen recognition by specific T cells is crucial to the pathophysiology of rheumatoid synovitis. We will discuss evolving concepts about T-cell involvement in RA and the roles for various T cell subsets in the development of joint abnormalities. The hypothesis that RA is a T-cell driven disease was put forward when studies of RA synovium showed numerous T cells carrying activation markers. These T cells were found to participate in the complex network of cell- and mediator-driven events leading to joint destruction. Conceivably, these T cells may be stimulated by an autoantigen (whether specific to the joints or ubiquitous), a highly conserved foreign protein cross-reacting with its human homolog, or a neo-antigen expressed as a result of posttranslational events. For many years, animal models have provided valuable evidence supporting a role for T cells in RA. We will review three murine models of arthritis caused by different mechanisms. In collagen-induced arthritis, the immune response to a joint antigen is mediated by pathogenic Th1 cells that elicit severe inflammatory synovitis. Spontaneous arthritis in K/BxN T-cell-receptor transgenic mice is related to an adaptive immune response against a ubiquitous protein whose end-stage effector mechanisms are heavily dependent on the innate immune system. In the SKG model of autoimmune inflammatory arthritis, a point mutation in the gene encoding a key signal-transduction molecule in T cells causes defective T cell selection in the thymus, which releases polyclonal autoreactive T cells. Studies in these and other animal models have established that a variety of T-cell subsets whose roles vary with cell location and disease stage can contribute to synovitis. Finally, in addition to direct autoimmune attack by effector T cells, arthritis may result from defective homeostatic control of immunity by regulatory T cells.

Boxing hundreds of thousands of particles in low-dose electron micrographs is one of the major bottle-necks in advancing toward achieving atomic resolution reconstructions of biological macromolecules. We have shown that a combination of pre-processing operations and segmentation can be used as an effective, automatic tool for identifying and boxing single-particle images. This paper provides a brief description of how this method has been applied to a large data set of micrographs of ice-embedded ribosomes, including a comparative analysis of the efficiency of the method. Some results on processing micrographs of tripeptidyl peptidase II particles are also shown. In both cases, we have achieved our goal of selecting at least 80% of the particles that an expert would select with less than 10% false positives

Obesity and overweight, well known risk factors for cardiovascular disease and type 2 diabetes, are now associated with Alzheimer's disease (AD). It remains to be determined if obesity and overweight contribute to the risk of developing AD through modulating levels of amyloid-beta (Abeta), a key molecule in AD pathogenesis. Thus, we investigated whether there were any associations between plasma Abeta levels and body mass index (BMI) or fat mass (FM) in a group of 18 healthy adults. A statistically significant correlation was found between BMI, FM, and plasma levels of Abeta42 (BMI r = 0.602, P = 0.008; FM r = 0.547, P = 0.019), the longer, more pathogenic form of Abeta, but not with plasma levels of the shorter, less pathogenic Abeta40. Although not significant, positive correlations between plasma levels of Abeta42 and levels of insulin and the inflammatory marker C-reactive protein (CRP), along with an inverse trend between plasma Abeta42 levels and levels of high density lipoprotein (HDL) were answered. These results suggest that proteins implicated in inflammation, cardiovascular disease and type 2 diabetes, which in turn are risk factors for AD, may contribute to the associations between BMI/FM and plasma Abeta42 levels. Longitudinal studies involving larger cohorts are required to determine if elevated body fat may predispose individuals to AD through increasing Abeta42 levels throughout early to late adulthood.

The nodes of Ranvier are regularly spaced gaps between myelin sheaths that are markedly enriched in voltage-gated sodium channels and associated proteins. Myelinating glia play a key role in promoting node formation, although the requisite glial signals remain poorly understood. In this study, we have examined the expression of glial proteoglycans in the peripheral and central nodes. We report that the heparan sulfate proteoglycan, syndecan-3, becomes highly enriched with PNS node formation; its ligand, collagen V, is also concentrated at the PNS nodes and at lower levels along the abaxonal membrane. The V1 isoform of versican, a chondroitin sulfate proteoglycan, is also present in the nodal gap. By contrast, CNS nodes are enriched in versican isoform V2, but not syndecan-3. We have examined the molecular composition of the PNS nodes in syndecan-3 knockout mice. Nodal components are normally expressed in mice deficient in syndecan-3, suggesting that it has a nonessential role in the organization of nodes in the adult. These results indicate that the molecular composition and extracellular environment of the PNS and CNS nodes of Ranvier are significantly distinct

The discovery of long-lived epithelial stem cells in the bulge region of the hair follicle led to the hypothesis that epidermal renewal and epidermal repair after wounding both depend on these cells. To determine whether bulge cells are necessary for epidermal renewal, here we have ablated these cells by targeting them with a suicide gene encoding herpes simplex virus thymidine kinase (HSV-TK) using a Keratin 1-15 (Krt1-15) promoter. We show that ablation leads to complete loss of hair follicles but survival of the epidermis. Through fate-mapping experiments, we find that stem cells in the hair follicle bulge do not normally contribute cells to the epidermis which is organized into epidermal proliferative units, as previously predicted. After epidermal injury, however, cells from the bulge are recruited into the epidermis and migrate in a linear manner toward the center of the wound, ultimately forming a marked radial pattern. Notably, although the bulge-derived cells acquire an epidermal phenotype, most are eliminated from the epidermis over several weeks, indicating that bulge stem cells respond rapidly to epidermal wounding by generating short-lived 'transient amplifying' cells responsible for acute wound repair. Our findings have implications for both gene therapy and developing treatments for wounds because it will be necessary to consider epidermal and hair follicle stem cells as distinct populations

BACKGROUND: Mosquitoes were collected in Heilongjiang province in 2002, four virus strains were isolated by inoculation of homogenates onto BHK cell lines. The viruses were identified. Multiple alignment and phylogenetic analysis were carried out by Clustal X (1.8) program.Amino acid (AA) analysis was carried out by GENEDOS (3.2). RESULTS: Biological characters of four newly isolated strains were examined and it was found that all of them could produce cytopathogenic effect (CPE) in BHK cells, killing sucking mice. Serological tests showed that all of these stains reacted positively to JEV antibodies. PrM and E gene regions were amplified and sequenced. Phylogenic analysis showed that all the newly isolated JEV strains belong to genotype III. Using the vaccine strains (SA14-14-2) as control, analysis of the E gene of the new strains and two JEV strains (47, Ha-3) isolated previously from Heilongjiang province showed that these new strains' nucleotide sequence had a homology of up to 99.9% and the amino acid sequence homology up to 99.8%, respectively. Compared with the standard JE vaccine strain SA-14-14-2 and the four new strains, the nucleotide sequence homology was 97.3% and amino acid sequence homology was between 96.8% and 97.0%, respectively. Compared with vaccine strain, there were seven common variations in all the four newly isolated strains. CONCLUSION: Four JE virus strains were isolated in Heilongjiang province. As compared to the vaccine strain, six variations were found in the newly isolated strains at the eight sites relevant to the virulence of the virus.

Cardiolipin is a unique mitochondrial phospholipid with an atypical fatty acid profile, but the significance of its acyl specificity has not been understood. We explored the enormous combinatorial diversity among cardiolipin species, which results from the presence of four fatty acids in each molecule, by integrated use of high-performance liquid chromatography, mass spectrometry, diacylglycerol species analysis, fatty acid analysis, and selective cleavage of fatty acids by phospholipase A2. The most abundant cardiolipin species from various organisms and tissues (human heart, human lymphoblasts, rat liver, Drosophila, sea urchin sperm, yeast, mung bean hypocotyls) contained only one or two types of fatty acids, which generated a high degree of structural uniformity and molecular symmetry. However, an exception was found in patients with Barth syndrome, in whom an acyltransferase deficiency led to loss of acyl selectivity and formation of multiple molecular species. These results suggest that restriction of the number of fatty acid species, rather than the selection of a particular kind of fatty acid, is the common theme of eukaryotic cardiolipins. This limits the structural diversity of the cardiolipin species and creates molecular symmetry with implications for the stereochemistry of cardiolipin