Design of ultrahigh-affinity and dual-specificity peptide antagonists of MDM2 and MDMX for P53 activation and tumor suppression

Peptide inhibition of the interactions of the tumor suppressor protein P53 with its negative regulators MDM2 and MDMX activates P53 in vitro and in vivo,representing a viable therapeutic strategy for cancer treatment.Using phage display techniques,we previously identified a potent peptide activator of P53,termed PMI(TSFAEYWNLLSP),with binding affinities for both MDM2 and MDMX in the low nanomolar concentration range.Here we report an ultrahigh affinity,dual-specificity peptide antagonist of MDM2 and MDMX obtained through systematic mutational analysis and additivitybased molecular design.Functional assays of over 100 peptide analogs of PMI using surface plasmon resonance and fluorescence polarization techniques yielded a dodecameric peptide termed PMI-M3(LTFLEYWAQLMQ)that bound to MDM2 and MDMX with K_(d)values in the low picomolar concentration range as verified by isothermal titration calorimetry.Co-crystal structures of MDM2 and of MDMX in complex with PMI-M3 were solved at 1.65 and 3.0 A resolution,respectively.Similar to PMI,PMI-M3 occupied the P53-binding pocket of MDM2/MDMX,which was dominated energetically by intermolecular interactions involving Phe3,Tyr6,Trp7,and Leu 10.Notable differences in binding between PMI-M3 and PMI were observed at other positions such as Leu4 and Met11 with MDM2,and Leu1 and Met11 with MDMX,collectively contributing to a significantly enhanced binding affinity of PMI-M3 for both proteins.By adding lysine residues to both ends of PMI and PMI-M3 to improve their cellular uptake,we obtained modified peptides termed PMI-2K(KTSFAEYWNLLSPK)and M3-2K(KLTFLEYWAQLMQK).Compared with PMI-2K,M3-2K exhibited significantly improved antitumor activities in vitro and in vivo in a P53-dependent manner.This super-strong peptide inhibitor of the P53-MDM2/MDMX interactions may become,in its own right,a powerful lead compound for anticancer drug development,and can aid molecular design of other classes of P53 activators as well for anticancer therapy.

Childhood adiposity, adult adiposity, and bone health

Importance:Childhood and adolescence are critical periods for lifelong bone mineral accrual,but few studies have determined the impact of childhood adiposity on adult bone density.Objective:To determine the long-term impact of childhood adiposity on adult areal bone mineral density(aBMD)and the effect of adult adiposity on this relationship.Methods:We conducted a longitudinal study of 1156 adults(56.3%men),for whom skinfold thickness(SFT)had been measured during childhood(6-18 years)and fat mass percentage(FMP)and aBMD were measured during adulthood(29-43 years).Adult aBMD in the lumbar spine(LS),femoral neck(FN),arms,and legs was measured using dual-energy X-ray absorptiometry.The direct effect of childhood SFT and its indirect effect through adult FMP on adult aBMD were estimated using general linear regression and a causal steps approach.Results:Significant positive associations between childhood SFT and adult aBMD were found in the LS in men(β=0.089,P=0.044)and in all the skeletal sites in women.With respect to the adult fat-bone relationship,high adult FMP was associated with low aBMD in most of the sites in men,but with high FN aBMD in women(β=0.144,P=0.002).Moreover,suppressive effects of adult FMP on the associations between childhood SFT and adult aBMD in the LS(-34.8%)and legs(-67.1%)of men,and a positive effect on the FN aBMD in women(17.0%)were identified.Interpretation:Childhood adiposity appears to have a positive long-term effect on adult aBMD,which may be reduced by adiposity in adult men but reinforced by adiposity in adult women.

Can spot urine measurement be a substitute for 24-hour urine measurement to estimate sodium intake in adolescents?

Importance:Several methods have been established in recent decades that allow use of spot urine to estimate dietary sodium intake.However,their accuracies have been controversial in children.Objective:To validate the performance of three commonly used methods-the Kawasaki,Tanaka,and International Cooperative Study on Salt,Other Factors,and Blood Pressure(INTERSALT)methods.Additionally,this study explored the accuracies of the Tanaka and INTERSALT methods by using spot urine samples taken at four separate times.Method:Forty-one adolescents aged 14 to 16 years completed two non-consecutive 24-hour urine collections and their mean values were used as reference data.The second-morning urine was used for assessment with the Kawasaki method;a casual spot urine and spot urine samples taken at four separate times(morning,afternoon,evening,and overnight)were used for assessment with the Tanaka and INTERSALT methods.Results:The mean differences were 1801 mg,542 mg,47 mg,and-31 mg for the Kawasaki,Tanaka,INTERSALT 1(with potassium),and INTERSALT2(without potassium)methods with their required spot urine,respectively.The proportions of relative difference levels within±10%were 4.9%for the Kawasaki method,19.5%for the Tanaka method,36.6%for the INTERSALT 1 method,and 36.6%for the INTERSALT2 method.Interpretation:The INTERSALT method seemed to provide minimally biased estimations of mean population sodium intake with casual spot urine.However,there is a need to be cautious regarding inconsistencies in estimation among different levels of sodium intake.The methods assessed in this study were unable to accurately estimate sodium intake at the individual level.

Analysis on the differences in the development of basic researchers in the field of Al in China

Artificial intelligence(AI)is an important driving force in the new round of scientific and technological revolution and industrial transformation,China must grasp the opportunity to its development.Basic researcher's ability was the inexhaustible driving force to promote the long-term development of AI.The paper focused on 2763 AI researchers who engaged in basic research.The paper analyzed the differences in city distribution and research direction of this group in China,and further explored the influence of different cities on research output,as well as the interactive influence between city and institution on their research output.The study found that there was a prominent phenomenon of aggregation of AI basic researchers in China,and their research fields were mainly focused on machine learning,computer vision,patterm recognition and data mining.The economic level of the city had a positive impact on the paper output and the project undertaken by researchers.The development vitality of the city had a positive impact on the researchers'patent output.The high-quality platform of the institution would make up for the disadvantages caused by the city's lower economy.Therefore,in China,it was necessary to determine the development orientation of cities at different levels so that they could play different roles in the industrial development.Economically underdeveloped cities should allocate resources rationally,enhance the deep cooperation between non-first-class institutions and local AI enterprises,and provide a good scientific research ecological environment for the growth of local AI basic researchers.