No abstract

Mediator is a multisubunit coactivator required for initiation by RNA polymerase II. The Mediator tail subdomain, containing Med15/Gal11, is a target of the activator Gcn4 in vivo, critical for recruitment of native Mediator or the Mediator tail subdomain present in sin4⌬ cells. Although several Gal11 segments were previously shown to bind Gcn4 in vitro, the importance of these interactions for recruitment of Mediator and transcriptional activation by Gcn4 in cells was unknown. We show that interaction of Gcn4 with the Mediator tail in vitro and recruitment of this subcomplex and intact Mediator to the ARG1 promoter in vivo involve additive contributions from three different segments in the N terminus of Gal11. These include the KIX domain, which is a critical target of other activators, and a region that shares a conserved motif (B-box) with mammalian coactivator SRC-1, and we establish that B-box is a critical determinant of Mediator recruitment by Gcn4. We further demonstrate that Gcn4 binds to the Gal11 KIX domain directly and, by NMR chemical shift analysis combined with mutational studies, we identify the likely binding site for Gcn4 on the KIX surface. Gcn4 is distinctive in relying on comparable contributions from multiple segments of Gal11 for efficient recruitment of Mediator in vivo.

No abstract

Oxidative modification of low-density lipoproteins (LDLs) is an important feature in the initiation and progression of atherosclerosis. Aminoguanidine (AMG), classically described as an inhibitor of advanced glycation end products, turned out to be also efficient in animal models as an antioxidant against lipid peroxidation. The originality of the present study was based on the simultaneous assessment of the oxidation of LDL lipid and protein moieties in order to characterize the molecular sites of AMG protection. Oxidation of the LDL lipid moiety was monitored by measuring conjugated dienes (CD) and hydroperoxide molecular species from cholesteryl esters (CEOOH) and phosphatidylcholines (PCOOH). LDL protein oxidative modifications were assessed by evaluating apoB carbonylation and fragmentation. The LDL oxidation was mediated by water gamma radiolysis, which has the advantage of being quantitative and highly selective with regard to the free radicals produced. Here, we reported that AMG resulted in a protection of LDLs against lipid peroxidation (both in the lag phase and in the propagation phase) and against apoB fragmentation in a concentration-dependent manner, due to the scavenging effect of AMG toward lipid peroxyl radicals. Paradoxically, AMG was poorly efficient against apoB carbonylation that began during the lag phase. We hypothesize that, even in the presence of AMG, a nonnegligible proportion of (*)OH radicals remained able to initiate oxidation of the LDL protein moiety, leading to apoB carbonylation.

No abstract

11030 Background: In 2020, the NCI funded a new educational consortium, NASDC (NCI Awardee Skills Development Consortium, RFA-CA-19-010 and -011), through four institutionally granted UE5 awards to deliver a specific course each and a U24 award as a Coordinating Center. The goal is to teach current early-career faculty NCI grantees skills in areas critical for successful independent academic cancer research careers. Courses focus on leadership and socioemotional skills, health disparities, immuno-oncology, and cell and gene therapy. Teaching will initially be virtual, given the COVID pandemic. Methods: A steering committee and four working groups were established to build the consortium infrastructure, including the NASDC (osu.edu) website. Clientele are early-career faculty PD/PI of a current NCI-funded grant (K01, K07, K08, K22, K23, K25, R00, R21, DP1, DP2, DP5, R01, R23, R29, R37, R56, RF1, RL1, U01), of whom 454 were directly contacted. Blast emails and social media were also used. We are reporting the characteristics of 154 applicants, who completed the RedCap application online. Results: 85% of the applicants are within the first 5 years of a faculty appointment, 87% at the assistant professor rank, and 65% on tenure track. 40% hold an M.D. degree and 72% a Ph.D. 81% are US citizens, 52% females, and 45/33/16/2/4%-11% are White/Asian/Black/Native Americans/Other–Hispanics/Latino. 76% work at NCI-designated comprehensive cancer centers. Mean protected research time is 80%. Non-mutually exclusive fields of research interest are therapeutics (46%), basic science (37%), disparities (34%) prevention (32%), public health (28%), and pediatrics (10%). 66% have received a K-award grant, 13% each an R21 or R00, and 3% an R01. Additionally, 35% had a second NCI grant as PI, 10% a third grant, and 60% had non-NCI grants. Reasons for applying included (1) not quite ready to lead a research team (42%), (2) need for stronger career mentoring (37%), and (3) not being fully confident in research skills (21%). Conclusions: Applicants to the new NCI educational consortium (NASDC) have a successful start to their academic career with a third having obtained more than one NCI award. Most applicants work at NCI-designated comprehensive cancer centers. As cancer research continues to evolve and has the potential to address critical health care needs of the nation, NASDC will strive to equip scientists to be leaders, teach advances in technology, and impart confidence in research skills.