Our laboratory has broad interest in the application of cutting edge ideas and technology to the study of disease-relevant issues. Major directions include inflammation, oxidative-stress, signal transduction, gene discovery, functional genomics and proteomics, gene regulation, molecular immunology, cancer research and neuro-inflammation. These divergent studies are incorporated into four major directions relying heavily on gene profiling, 2D gel-mass spectroscopy and proteome analysis, gene-ablation in mice and RNA interference. These new approaches are integrated with traditional approaches employed to study signal transduction, transcription, protein-interaction and modification, coupled with biologic studies to understand innate and adaptive immunity in diseases such as infection, inflammation and cancer. Trainees typically are exposed to an enormous repertoire of expertise and approaches, and they are highly competitive after graduation.

1. Molecular and transcriptional control of immune response - We have focused on a transcriptional master regulator of Major Histocompatibility (MHC) genes called CIITA (class II transactivator). CIITA is extremely important as patients with defects in the gene exhibit severe immunodeficiency. It has even broader clinical importance as polymorphism (SNP) in the CIITA has been linked to multiple sclerosis, arthritis and heart disease (the latter has a strong inflammatory component). CIITA promotes the recruitment of DNA-binding protein, transcription cofactors, and histone acetylases/methylases to the promoter as determined by in vivo footprinting and chromatin immunoprecipitation. More recently we found that CIITA also activates the plexin-A1 gene in dendritic cells. Plexin-A1 has not been previously reported in the immune system, and is typically thought to be important for neuronal interaction and retraction. Our new finding presents a completely new framework to think about how immune cells attract and repulse each other. We are pursuing the following directions: (1) A significant effort is devoted to understanding how CIITA transcriptionally activates plexin-A1 expression in dendritic cells (2) We show that plexin-A1 controls Rho GTPase activation, actin polarization and antigen presentation; we want to understand how plexin affects these different processes. (3) Other plexin molecules are differentially expressed by distinct immune cell subpopulations. We are trying to understand their roles in immunity.

2. CATERPILLER (CLR) OR NOD: A Family of New Inflammatory and Apoptotic Genes - Based on the structure of CIITA, we have found a large family of genes that encode similar structural motifs as CIITA, which we have termed the CATERPILLER gene family. These mammalian genes are conserved all through plants (R genes). In plants, R genes are important for immune defense against bacteria, viruses, fungi, parasites and even insecticides. It is anticipated that mammalian CLRs have a similar function. In support of this, several human CLR genes are the primary genetic causes of immunologic disorders, including immunodeficiency, Inflammatory Bowel Disease, and periodic auto-inflammation. Our studies show that these genes are crucial in the control of inflammatory, anti-inflammatory and apoptotic responses in mammals. They can reduce or amplify signaling pathways mediated by the Toll-like receptor (TLR) family, TNF receptor family, IL-1 receptor, NF-?B, and AP-1. RNA interference, gene ablation, genomics, yeast two-hybrid, biochemical and proteomics analyses are performed to understand the functions of these novel genes. In addition to understanding their role in the control of inflammation, another focus is on the role of CLRs in apoptosis. CLR proteins are similar in structure to an apoptotic inducer, Apaf-1. We find that mutant CLR associated with disease causes increased apoptosis. Thus CLR proteins affect both inflammatory and apoptotic processes. This project involves understanding how CLR affects cell signaling (such as in the TLR, TNF, IL-1, NF-kB, AP-1 and MAPK pathways), apotosis (such as caspase activation and apoptosome formation), and elucidating the biological role of these proteins in infection, inflammation and autoimmunity.

3. New Biomarkers and the Importance of Oxidative Stress in Cancer - Biomarkers for cancer will play an increasingly important role for the diagnosis, prognosis and treatment of patients. We searched for biomarkers that accompany successful chemotherapy by proteomic array analysis, and found a novel marker. Increased DJ-1 expression is associated with lung, breast and ovarian cancers. DJ-1 has central role in stabilizing anti-oxidative stress in lung tumors. This is achieved by stabilizing transcription factors in the anti-oxidative pathways. This is highly relevant because lung tissues are constantly exposed to oxidative stress. DJ-1 expression is heightened in lung cancers to protect the cancers from oxidative stress. Intriguingly, DJ-1 is mutated in Parkinson's patients, and causes increased neuronal cell death. We hypothesize that DJ-1 normally protects cells from oxidiative stress. In cancer, elevated DJ-1 protects cancer cells, while the Parkinson mutation results in a defective protein and reduced neuronal survival. This project relies on RNA interferences and DJ-1 defective mice to understand the in vitro and in vivo function of DJ-1. In addition, experiments are ongoing to assess the validity of DJ-1 as a cancer prognostic or diagnostic biomarker.

4. The Detrimental and Beneficial Roles of CNS Inflammation in Disease Progression and Resolution - Inflammation occurs in a number of neurologic diseases such as Alzheimer's, Parkinson's, Huntington's and multiple sclerosis (MS). Inflammation in the CNS includes the induction of interleukins, complement, tumor necrosis factors, nitric oxide, class I and II MHC antigens. To examine the role of neuroinflammatory during disease progression and resolution, we have used a disease model where demyelination and remyelination can be predictably induced by feeding or withdrawing a neurotoxicant in the diet. Using mice with mutations in inflammatory genes, we found that many of these genes are not only crucial in disease progression (demyelination), but also in disease resolution (remyelination). This is unexpected and clearly demonstrates that not all inflammatory responses are bad. In specific we found that while TNF plays a minor role during demyelination, it is crucial for normal remyelination to occur. In contrast, a TNF-related gene, lymphotoxin worsens demyelination, but has little effect on the repair process. Hence we suggest that blocking.