Faculty Bibliography

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

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

Mycobacterium tuberculosis infects millions worldwide. The Structural Genomics Consortium for M. tuberculosis has targeted all genes from this bacterium in hopes of discovering and developing new therapeutic agents. Open reading frame Rv0793 from M. tuberculosis was annotated with an unknown function. The 3-dimensional structure of Rv0793 has been solved to 1.6 A resolution. Its structure is very similar to that of Streptomyces coelicolor ActVA-Orf6, a monooxygenase that participates in tailoring of polyketide antibiotics in the absence of a cofactor. It is also similar to the recently solved structure of YgiN, a quinol monooxygenase from Escherichia coli. In addition, the structure of Rv0793 is similar to several structures of other proteins with unknown function. These latter structures have been determined recently as a result of structural genomic projects for various bacterial species. In M. tuberculosis, Rv0793 and its homologs may represent a class of monooygenases acting as reactive oxygen species scavengers that are essential for evading host defenses. Since the most prevalent mode of attack by the host defense on M. tuberculosis is by reactive oxygen species and reactive nitrogen species, Rv0793 may provide a novel target to combat infection by M. tuberculosis.

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

BACKGROUND: To study the molecular characteristics of YN92-4 strain isolated from mosquitoes in Yunnan Province and define its classification. METHODS: The S segment of YN92-4 strain was amplified and sequenced by 2 different sets of primers. The phylogenic tree of S fragment was constructed by Phylip bio-software. The amino acid sequences of N and NSs proteins were also studied. RESULTS: YN92-4 strain could be amplified by 2 sets of primers respectively, S segment showed a highest homology with Batai virus (X73464), reached 96.4%, the homology of protein N and NSs amio-acid sequence with Batai virus was 99.1% and 98% respectively. CONCLUSION: The YN92-4 strain belongs to Batai virus, this is the first report of molecular biological identification of Batai virus in China.

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: To survey arboviruses in Yunnan province. METHODS: Mosquitoes were collected from Yunnan Province in 2002 and 2004. Virus strains were isolated by the inoculation of homogenates of the mosquitoes onto BHK cell line. The isolated strains and their molecular biological characteristics were identified by real-time PCR, reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescent antibody technique. RESULTS: Twelve strains of viruses producing CPE in BHK cells were isolated from 4810 mosquitoes. All the 12 isolates were identified to be Japanese encephalitis viruses. Genotype analysis showed the new virus (DL-0437 strain) belonged to genotype III. CONCLUSION: Twelve strains of Japanese encephalitis viruses were isolated from mosquito pools collected in Yunnan. It was the first isolation of genotype III Japanese encephalitis viruses in Yunnan Province in recent years.

Respiratory dysfunction during sepsis is common. However, although lung function can often be adequately supported, death frequently results from cardiovascular collapse. Despite intense investigation, the mechanism underlying the myocardial dysfunction of sepsis remains unclear. Macrophage migration inhibitory factor (MIF), an important cytokine released in sepsis and the acute respiratory distress syndrome, is a known cardiac depressant. We hypothesized that MIF released from the lung results in myocardial dysfunction during sepsis. In murine models of polymicrobial sepsis, we demonstrate a significant increase in the lungs of total and lavagable MIF between 20 and 30 h post induction of sepsis. At 30 h post sepsis, the lungs released MIF into the pulmonary circulation, increasing the plasma concentration by up to 51% in a single pass. Exogenous MIF, instilled into the lungs, increased alveolar keratinocyte-derived chemokine (KC), Macrophage inflammatory protein-2 (MIP2), and tumor necrosis factor alpha (TNFalpha) at 3 h, and plasma KC and MIP2 at 6 h postinstillation. This was associated with an increase in p38 mitogen-activated protein kinase and c-Jun N-terminal kinase phosphorylation. Because changes in mitogen-activated protein kinase activation can lead to myocardial depression, these data suggest that MIF released from the lungs may be responsible, at least in part, for the cardiac dysfunction seen in the late stages of sepsis