Qualitatively Different T Cell Phenotypic Responses to IL-2 versus IL-15 Are Unified by Identical Dependences on Receptor Signal Strength and Duration

IL-2 and IL-15 are common γ-chain family cytokines involved in regulation of T cell differentiation and homeostasis. Despite signaling through the same receptors, IL-2 and IL-15 have non-redundant roles in T cell biology, both physiologically and at the cellular level. The mechanisms by which IL-2 and IL-15 trigger distinct phenotypes in T cells remain elusive. To elucidate these mechanisms, we performed a quantitative comparison of the phosphotyrosine signaling network and resulting phenotypes triggered by IL-2 and IL-15. This study revealed that the signaling networks activated by IL-2 or IL-15 are highly similar and that T cell proliferation and metabolism are controlled in a quantitatively distinct manner through IL-2/15R signal strength independent of the cytokine identity. Distinct phenotypes associated with IL-2 or IL-15 stimulation therefore arise through differential regulation of IL-2/15R signal strength and duration because of differences in cytokine–receptor binding affinity, receptor expression levels, physiological cytokine levels, and cytokine–receptor intracellular trafficking kinetics. These results provide important insights into the function of other shared cytokine and growth factor receptors, quantitative regulation of cell proliferation and metabolism through signal transduction, and improved design of cytokine based clinical immunomodulatory therapies for cancer and infectious diseases.National Institutes of Health (U.S.) (Grant U54CA11927)National Institutes of Health (U.S.) (Grant R01 AI065824)United States. Army Research Office (Institute for Collaborative Biotechnologies Grant W911NF-09-0001

dAKAP1: A mitochondrial AKAP that coordinates local translation

Thesis (Ph.D.)--University of Washington, 2019A-Kinase anchoring proteins (AKAPs) are a structurally diverse family of proteins defined by the ability to bind protein kinase A (PKA). AKAPs process and integrate a variety of intracellular signals by sequestering PKA with other signaling enzymes such as kinases, phosphodiesterases, and phosphatases. dAKAP1 tethers both PKA and protein phosphatase 1 (PP1) to the outer mitochondrial membrane and contains RNA and protein interaction domains that permit the clustering of signaling enzymes with the post-transcriptional machinery. The function of RNA binding by dAKAP1 at the outer mitochondrial membrane, however, is largely unresolved. I investigated two main questions: what are the protein and RNA binding partners of dAKAP1? and what is the physiological significance of the association of these molecules with dAKAP1? In order to answer the first question, I utilized mass spectrometry to identify protein interacting partners of dAKAP1 and discovered that dAKAP1 interacts with protein subcomplexes with RNA regulatory functions. I validated the interaction of one of these subcomplexes, LARP4/PABPC1, and determined that dAKAP1 binding of RNA is required for its localization to the outer mitochondrial membrane. I utilized RNA-Seq to identify RNA interacting partners of dAKAP1 and discovered that dAKAP1 can interact with RNAs that encode mitochondrial proteins. In order to answer the second question, I investigated the local translation of proteins encoded by RNA interacting partners of dAKAP1 at the mitochondria. I observed that dAKAP1-mediated anchoring of the SDHA mRNA directly correlates with mitochondrial SDHA protein levels. Though alternation of this anchoring is not sufficient to drive metabolic change, I also correlate a decrease of SDHA with a decrease in dAKAP1 levels across four different breast cancer cell lines. Collectively, my work suggests that dAKAP1 anchoring of both RNA and RNA-regulatory proteins is important for the local translation of at least one protein, SDHA, involved in the critical mitochondrial function of oxidative phosphorylation

Association of NTRK3 and its interaction with NGF suggest an altered cross-regulation of the neurotrophin signaling pathway in eating disorders

Eating disorders (EDs) are complex psychiatric diseases that include anorexia nervosa and bulimia nervosa, and have higher than 50% heritability. Previous studies have found association of BDNF and NTRK2 to ED, while animal models suggest that other neurotrophin genes might also be involved in eating behavior. We have performed a family-based association study with 151 TagSNPs covering 10 neurotrophin signaling genes: NGFB, BDNF, NTRK1, NGFR/p75, NTF4/5, NTRK2, NTF3, NTRK3, CNTF and CNTFR in 371 ED trios of Spanish, French and German origin. Besides several nominal associations, we found a strong significant association after correcting for multiple testing (P = 1.04 × 10−4) between ED and rs7180942, located in the NTRK3 gene, which followed an overdominant model of inheritance. Interestingly, HapMap unrelated individuals carrying the rs7180942 risk genotypes for ED showed higher levels of expression of NTRK3 in lymphoblastoid cell lines. Furthermore, higher expression of the orthologous murine Ntrk3 gene was also detected in the hypothalamus of the anx/anx mouse model of anorexia. Finally, variants in NGFB gene appear to modify the risk conferred by the NTRK3 rs7180942 risk genotypes (P = 4.0 × 10−5) showing a synergistic epistatic interaction. The reported data, in addition to the previous reported findings for BDNF and NTRK2, point neurotrophin signaling genes as key regulators of eating behavior and their altered cross-regulation as susceptibility factors for EDs