Current Molecular Medicine - Volume 3, Issue 4, 2003

Dr. James B. Sidbury, Jr. passed away in Mount Vernon, Washington on February 17, 2003. He was the Scientific Director of the National Institute of Child Health and Human Development (NICHD), of the National Institutes of Health (NIH) from 1975 to 1981 and remained at the NICHD as a Scientist Emeritus until a year before his death. We were very fortunate to have him serve as an Associate Editor of Current Molecular Medicine.Jim Sidbury was born in Wilmington, North Carolina. He received his undergraduate training at Yale University graduating in 1944. He studied medicine at Columbia University in New York and received his M.D. degree in 1947. He was a practicing pediatrician at the Babies Hospital in Wilmington for several years before joining the faculty at Johns Hopkins University Medical School in 1955. He returned to his home state of North Carolina and served in the pediatric faculty of Duke University in Durham, N.C. from 1961 to 1975 when he was appointed the Scientific Director of NICHD.One of Jim Sidbury's life long scientific interests was to understand the molecular mechanisms of glycogen storage diseases (GSD) and to develop an effective treatment. In collaboration with his colleagues he was able to develop the only treatment for GSDs using uncooked corn starch and to delineate the molecular mechanism of GSD 1a. Those of us who knew Jim closely will remember him as an unassuming gentleman who was full of wit and humor, an imaginative scientist, a compassionate physician, a trusted friend, a helpful colleague and above all, a genuine human being. His devotion and concern for improving children's health and welfare are his legacy. Aside from his dedication to science and medicine, he enjoyed sailing, which led him to spend his retired life in Deale, a small community on the Chesapeake Bay. Jim Sidbury married Alice Lucas who died in 1977. He is survived by two sons and three daughters, five grand children, two sisters as well as seven nephews and nieces.

Recent experiments have unravelled novel signal transduction pathways that involve the SRC homology 2 (SH2) domain adapter protein SHB. SHB is ubiquitously expressed and contains proline rich motifs, a phosphotyrosine binding (PTB) domain, tyrosine phosphorylation sites and an SH2 domain and serves a role in generating signaling complexes in response to tyrosine kinase activation. SHB mediates certain responses in platelet-derived growth factor (PDGF) receptor-, fibroblast growth factor (FGF) receptor-, neural growth factor (NGF) receptor TRKA-, T cell receptor-, interleukin-2 (IL-2) receptor- and focal adhesion kinase- (FAK) signaling. Upstream of SHB in some cells lies the SRC-like FYN-Related Kinase FRK / RAK (also named BSK / IYK or GTK). FRK / RAK and SHB exert similar effects when overexpressed in rat phaeochromocytoma (PC12) and β-cells, where they both induce PC12 cell differentiation and β-cell proliferation. Furthermore, β-cell apoptosis is augmented by these proteins under conditions that cause β-cell degeneration. The FRK / RAK-SHB responses involve FAK and insulin receptor substrates (IRS) -1 and -2.Besides regulating apoptosis, proliferation and differentiation, SHB is also a component of the T cell receptor (TCR) signaling response. In Jurkat T cells, SHB links several signaling components with the TCR and is thus required for IL-2 production. In endothelial cells, SHB both promotes apoptosis under conditions that are anti-angiogenic, but is also required for proper mitogenicity, spreading and tubular morphogenesis. In embryonic stem cells, dominant-negative SHB (R522K) prevents early cavitation of embryoid bodies and reduces differentiation to cells expressing albumin, amylase, insulin and glucagon, suggesting a role of SHB in development.In summary, SHB is a versatile signal transduction molecule that produces diverse biological responses in different cell types under various conditions. SHB operates downstream of GTK in cells that express this kinase.

Obesity has become a worldwide public health problem affecting millions of people. A disruption of the balance between energy intake and energy expenditure is believed to be the major cause of obesity. Substantial progress has been made in deciphering the pathogenesis of energy homeostasis over the past few years. The fact that obesity is under strong genetic control has been well established. Human monogenic obesity is rare in large populations, the most common form of obesity is considered to be a polygenic disorder arising from the interaction of multiple genetic and environmental factors. Here, we attempt to briefly review the most recent understanding of molecular mechanisms involved in energy homeostasis and adipogenesis. We discuss the advantages and disadvantages of various approaches commonly used in search for susceptibility genes for obesity. The main results from these genetic studies are summarized, with comments made on the most striking or representative findings. Finally, the implications of the recent advances in the understanding of molecular genetic mechanisms of body weight regulation on prevention and therapeutic intervention of obesity will be discussed.

The human γ-herpesvirus Epstein-Barr virus establishes latent, life-long infection in more than 95% of the human adult population. Despite its growth transforming capacity, most carriers control EBV associated malignancies efficiently and remain free of EBV+ tumors. It is commonly accepted that lymphoblastoid cells, expressing all EBV latent antigens, are targeted by the immune system and cause tumors only in immune-suppressed individuals. However, immune control of EBV associated malignancies which express only three or one EBV latent antigen is less obvious. Recent studies have addressed the pattern of EBV latent infection in healthy EBV carriers and the identity of EBV derived target antigens for CD4+ T cells. The results suggest that immune surveillance also extends to tumors, which have down-regulated most EBV latent antigens and therefore escape EBV specific immune recognition at least in part. EBV specific immunity that targets these tumors in healthy EBV carriers seems to fail specifically during the development of Hodgkin's disease, nasopharyngeal carcinoma and Burkitt's lymphoma. These three EBV+ tumors appear to subdue EBV immunity against the remaining EBV latent antigens in different ways or profit from the effect of other pathogens on EBV specific immune responses, when they develop in otherwise immune competent individuals. While immune control and immune escape of these so-called spontaneously arising EBV associated malignancies is just beginning to be understood, immune control of persisting EBV infection can serve as a model for tumor immune surveillance in general.

Bulimia nervosa (BN) and Anorexia Nervosa (AN) are currently classified as eating disorders (ED). Both disorders are the product of complex interaction between physiological and psychological and social processes; they are characterized by abnormal eating behavior. However, patients with BN differ from AN in their nutritional state and response of treatment with serotonin-selective reuptake inhibitor (SSRI) as well as frequency of comorbidity of mood and anxiety disorders. Although biological mechanisms of both BN and AN are largely unknown, excess of both feeding-stimulatory and feeding inhibitory signaling in AN have been indicated. This report reviews data that point to the hypothesis that dysregulation of monoaminergic and new peptidergic circuitry controlling food intake and energy expenditure play a major role in the eating behavior of BN.

Significant advances have been made over the past few years concerning the cellular and molecular events underlying ischemic cell death. The brain succumbs to ischemic injury as a result of loss of metabolic stores, excessive intracellular calcium accumulation, oxidative stress, and potentiation of the inflammatory response. Neurons can also die via necrotic or apoptotic mechanisms, depending on the nature and severity of the insult. While it has been widely held that ischemia is notable for cessation of protein synthesis, brain regions with marginal reduction in blood supply are especially capable of expressing a variety of genes, the functions of many of which are only beginning to be understood. Gene expression is also upregulated upon reperfusion and reoxygenation. As a result, a number of signaling pathways have been identified and are now known to contribute to ischemic progression or, in some cases, attempts at self preservation. This review will focus on the roles of stress genes, apoptosis-related genes, and inflammation. Knowledge of such molecular events has fueled interest in developing specific molecular targets with the hope of someday affecting outcome in clinical stroke.

Higher animals establish host defense by orchestrating innate and adaptive immunity. This is mediated by professional antigen presenting cells, i.e. dendritic cells (DCs). DCs can incorporate pathogens, produce a variety of cytokines, maturate, and present pathogen-derived peptides to T cells, thereby inducing T cell activation and differentiation. These responses are triggered by microbial recognition through type I transmembrane proteins, Toll-like receptors (TLRs) on DCs. TLRs consist of ten members and each TLR is involved in recognizing a variety of microorganism-derived molecular structures. TLR ligands include cell wall components, proteins, nucleic acids, and synthetic chemical compounds, all of which can activate DCs as immune adjuvants.Each TLR can activate DCs in a similar, but distinct manner. For example, TLRs can be divided into subgroups according to their type I interferon (IFN) inducing ability. TLR2 cannot induce IFN-α or IFN-β, but TLR4 can lead to IFN-β production. Meanwhile, TLR3, TLR7, and TLR9 can induce both IFN-α and IFN-β. Recent evidences suggest that cytoplamic adapters for TLRs are especially crucial for this functional heterogeneity. Clarifying how DC function is regulated by TLRs should provide us with critical information for manipulating the host defense against a variety of diseases.

Leukocyte recruitment to sites of inflammation, infection or vascular injury is a complex event, depending on a tightly coordinated sequence of leukocyte-endothelial- and leukocyte-platelet interactions, which are controlled by the expression and activation of various adhesion receptors and protease systems. The present review will focus on novel aspects of the regulation of integrindependent leukocyte adhesion by haemostatic factors and bacterial products. In particular, after a short overview of leukocyte recruitment, the review (i) will focus on the crosstalk between haemostatic factors and adhesion molecules with respect to leukocyte extravasation based on the paradigms of the urokinase receptor and high molecular weight kininogen, (ii) will provide information on novel mechanisms for the regulation of leukocyte recruitment by bacterial proteins, on the basis of the antiinflammatory role of Staphylococcus aureus extracellular adhesive protein and (iii) will draw attention to the junctional adhesion molecules, a novel family of adhesive receptors that are counter-receptors for leukocyte integrins and mediate vascular cell interactions. The better understanding of the interactions between vascular cells and particularly of integrin-dependent leukocyte adhesion may lead to the development of novel therapeutical concepts in inflammatory vascular disorders.