Melanocortin receptor accessory proteins (MRAPs) modulate signaling of melanocortin receptors in vitro. To investigate the physiological role of brain-expressed Melanocortin 2 Receptor Accessory Protein 2 (MRAP2), we characterized mice with whole body and brain-specific targeted deletion of Mrap2, both of which develop severe obesity at a young age. Mrap2 interacts directly with Melanocortin 4 Receptor (Mc4r), a protein previously implicated in mammalian obesity, and it enhances Mc4r-mediated generation of the second messenger cyclic AMP, suggesting that alterations in Mc4r signaling may be one mechanism underlying the association between Mrap2 disruption and obesity. In a study of humans with severe, early-onset obesity, we found four rare, potentially pathogenic genetic variants in MRAP2, suggesting that the gene may also contribute to body weight regulation in humans.

Generation of effective T helper cell type 1 (Th1) responses are required for immunity against intracellular bacteria. However, some intracellular bacteria require Interleukin (IL)-17 to drive Th1 immunity and subsequent protective host immunity. Here, in a model of Mycobacterium bovis Bacille Calmette Guerin (BCG) vaccination in mice, we demonstrate that the dependence on IL-17 to drive Th1 responses is a host mechanism to overcome bacteria-induced IL-10 inhibitory effects. We show that BCG-induced Prostaglandin-E2 (PGE2) promotes the production of IL-10 which limits Th1 responses, while simultaneously inducing IL-23 and Th17 differentiation. The ability of IL-17 to down-regulate IL-10 and induce IL-12 production allows the generation of subsequent Th1 responses. Accordingly, BCG-induced Th17 responses precedes generation of Th1 responses in vivo, while absence of IL-23 pathway decreases BCG vaccine-induced Th17 and Th1 immunity and subsequent vaccine-induced protection upon M.tuberculosis challenge. Importantly, in the absence of IL-10, BCG-induced Th1 responses occurs in an IL-17-independent manner. These novel data project the IL-23/IL-17 pathway in driving Th1 responses, specifically, to overcome IL-10 mediated inhibition and that in absence of IL-10, the generation of BCG induced Th1 immunity is IL-17-independent.

The chicken bursa of Fabricius is a primary lymphoid tissue important for B-cell development. Our long-term goal is to understand the role of bursal microenvironment in an early B-cell differentiation event initiating repertoire development through immunoglobulin gene conversion in the chick embryo. We hypothesize that early bursal B-cell differentiation is guided by signals through cytokine receptors. Our theory is based on previous evidence for expression of the receptor tyrosine kinase superfamily members and interleukin receptors in unseparated populations of bursal B-cells and bursal tissue. Knowledge of the expressed genes that are responsible for B-cell differentiation is a prerequisite for understanding the bursal microenvironment's function. This project uses transcriptomic analysis to evaluate gene expression across early B-cell development. RNA-seq was performed with total RNA isolated from bursal B-cells at embryonic day (ED) 16 and ED 19 (n = 3). Approximately 90 million high-quality clean reads were obtained from the cDNA libraries. The analysis revealed differentially expressed genes involved in the Jak-STAT pathway, Wnt signaling pathway, MAPK signaling pathway, metabolic pathways including tyrosine metabolism, Toll-like receptor signaling pathway, and cell-adhesion molecules. The genes predicted to encode surface receptors, signal transduction proteins, and transcription factors identified in this study represent gene candidates for controlling B-cell development in response to differentiation factors in the bursal microenvironment.

Avian pathogenic Escherichia coli causes one of the most detrimental bacterial diseases to the United States poultry industry, colibacillosis. Colibacillosis leads to decreased performance, early mortality, and subsequent production loss.