Jun Zhao - US grants

[unreadable] DESCRIPTION (provided by applicant): Depression has been considered to be the major psychiatric disease of the 20th century. The norepinephrine (NE) system is implicated in the etiology and treatment of depression, and several drugs that bind the NE transporter (NET) exhibit antidepressant properties. The NET has become an extremely important target of drug development research, and is also thought to be involved in the pathophysiology of several psychiatric disorders. Yet there have been few reports of promising NET radiotracers with characteristics appropriate for in vivo imaging studies. This project aims to develop improved NET radioligands labeled with carbon-11 and fluorine-18 for PET imaging, including ligands with higher affinity and selectivity but with lower lipophilicity than most previously reported probes. To accomplish this, a series of novel (R)-N-methyl 3-(substituted)-pyridinoxyl-3-phenylpropanamines (MPPA) and (S,S)-2-substituted- phenoxypyridinyl morpholines (PPYM), designed starting from the NET binding medications nisoxetine and reboxetine, will be synthesized. These compounds will be less lipophilic due to the inclusion of pyridine, pyrimidine and other heteroaromatic rings. The overall change in molecular size and weight are relatively small, and their NET affinity and selectivity should be preserved. In vitro evaluations of lipophilicity and affinity to human NET, dopamine transporters (DAT) and serotonin transporters (SERT) will be carried out. Those derivatives with appropriate in vitro characteristics will be labeled with either carbon-11 or fluorine-18 for in vivo evaluation in rats. The regional brain uptake over time will be measured, blocking studies will be performed to assess the degree of NET selective binding, and plasma and regional brain metabolite analyses will be carried out. The realization of improved PET NET radioligands will provide an important advance, allowing studies of NET density alterations associated with depression and other psychiatric disorders, and providing a much needed tool for drug dose versus occupancy studies in the human CNS. [unreadable] [unreadable]

PROJECT SUMMARY Human Kaposi?s Sarcoma-associated Herpesvirus (KSHV) is the etiological agent of multiple cancers. However, the molecular details concerning the tumorigenesis of KSHV are not well understood. Our recent studies indicate that herpesviruses employ protein deamidation to evade innate immune response. To probe the role of protein deamidation in fundamental biological processes, we performed a focused screen targeting cellular glutamine amidotransferases (GAT), a potential protein deamidases family. We identified one glutamine amidotransferase as a negative regulator of NF-?B activation. In our preliminary studies, we found that the GAT possessed intrinsic protein deamidating ability to deamidate NF-?B transcription factor to dampen its ability to transactivate NF-?B genes. Remarkably, deamidation promoted aerobic glycolysis to promote cell proliferation and tumorigenesis. Furthermore, KSHV hijacks the cellular mechanism to induce NF-?B deamidation and promote cell proliferation, thereby inducing tumor formation. Our findings support the overarching hypothesis a nucleotide biosynthetic enzyme deamidates a NF-?B subunit to reprogram metabolism, thus promoting cell proliferation and tumorigenesis, and that KSHV hijacks this mechanism to achieve persistent infection. To test this central hypothesis, I propose three aims in this project: 1) Elucidate the GAT-mediated deamidation of a NF-?B subunit and downregulation of NF-?B activation; 2) Delineate the metabolic reprogramming by GAT-mediated deamidation; and 3) Characterize a viral mechanism that hijacks the cellular deamidation to promote proliferation and tumor formation during KSHV latent infection. In the K99 phase, I will achieve the following three sub aims: 1) characterize the molecular detail of the NF-?B deamidation (Aim 1A); 2) examine the role of deamidation in innate immune defense (Aim 1B); and 3) dissect the mechanism of deamidation-mediated metabolic reprogramming (Aim 2A). In the R00 phase, I will complete Aim 2 by defining the role of NF-?B deamidation in proliferation and tumorigenesis of diverse cancer cell lines. Furthermore, I will investigate the mechanism by which KSHV promotes NF-?B deamidation and define its role in metabolism and tumorigenesis during KSHV infection. In summary, the K99/R00 project will characterize novel functions of a cellular metabolic enzyme (in nucleotide synthesis) and a key transcription factor (a NF-?B subunit), and elucidate a new mechanism governing metabolic reprogramming to drive cell proliferation, thereby offering fresh insight into the metabolic regulation during KSHV infection. It will establish the foundation for my long-term career goals to study protein deamidations in cellular metabolism, KSHV-associated tumorigenesis and translational applications to antiviral/antitumor therapies.