Targeting Divalent Metal Ions at the Active Site of the HIV-1 RNase H Domain: NMR Studies on the Interactions of Divalent Metal Ions with RNase H and Its Inhibitors

HIV-1 reverse transcriptase (RT) RNase H (HIV-RH) is a key target of anti-AIDS drugs. Metal-chelating compounds are an important class of chemicals in pharmacological drug discovery, especially in relation to HIV-RT and the highly-related HIV-integrase. The correlation between the metal-chelating properties and enzyme activities of the metal chelators is always of high scientific interest, as an understanding of this may accelerate the rational optimization of this class of inhibitors. Our NMR data show that Mg2+ and Ca2+ bind specifically to the active site of the RNase H domain and two Mg2+ ions sequentially bind one molecule of RNase H. We also demonstrate here, using saturated and unsaturated tricyclic N-hydroxypyridones designed to block the active site, that the primary binding sites and affinities of divalent metal ions are correlated with the structures of the chelating motifs. Chemical shift perturbation studies of protein/metal-ion/compound ternary complexes also indicate that divalent metal ions play important roles for the specific interaction of the compounds with the RNase H active site.

Structure-based design and optimization lead to the identification of novel dihydrothiopyrano[3,2-d]pyrimidine derivatives as potent HIV-1 inhibitors against drug-resistant variants

With our continuous endeavors in seeking potent anti-HIV-1 agents,we reported here the discovery,biological characterization,and druggability evaluation of a class of nonnucleoside reverse transcriptase inhibitors.To fully explore the chemical space of the NNRTI-binding pocket,novel series of dihydrothiopyrano[3,2-d]pyrimidines were developed by employing the structure-based design strategy.Most of the derivatives were endowed with prominent antiviral activities against HIV-1 wild-type and resistant strains at nanomolar levels.Among them,compound 23h featuring the aminopiperidine moiety was identified as the most potent inhibitor,with EC50values ranging from 3.43 to 21.4 nmol/L.Especially,for the challenging double-mutants F227L+V106A and K103N+Y181C,23h exhibited 2.3-to 14.5-fold more potent activity than the first-line drugs efavirenz and etravirine.Besides,the resistance profiles of 23h achieved remarkable improvement compared to efavirenz and etravirine.The binding target of 23h was further confirmed to be HIV-1 reverse transcriptase.Molecular modeling studies were also performed to elucidate the biological evaluation results and give guidance for the optimization campaign.Furthermore,no apparent inhibition of the major CYP450 enzymes and hERG channel was observed for 23h.Most importantly,23h was characterized by good pharmacokinetic properties and excellent safety in vivo.Collectively,23h holds great promise as a potential candidate for its effective antiviral efficacy and favorable drug-like profiles.

The Rational Combination Strategy of Immunomodulatory Latency Reversing Agents and Novel Immunotherapy to Achieve HIV-1 Cure

Human immunodeficiency virus(HIV)-1 infection creates a persistent latent reservoir even after antiretroviral therapy,which is the main barrier to HIV cure.One of the most explored strategies is the use of latent reversal agents(LRAs)to activate HIV latent reservoirs,followed by immunotherapy to remove infected cells.Immunomodulatory LRAs have the dual advantage of activating viral latency and promoting immune cell elimination of HIV-infected cells.The emergence of novel immunotherapies has also enhanced the possibility ofHIV clearance.Here we review the activity and potential mechanisms of immunomodulatory agonists and immunotherapies.The possible combinational strategies to achieve HIV functional cure and the problems encountered using this approach are discussed.

Synthesis and anti-HIV activities of phorbol derivatives

In this study,37 derivatives of phorbol esters were synthesized and their anti-HIV-1 activities evaluated,building upon our previous synthesis of 51 phorbol derivatives.12-Para-electron-acceptor-trans-cinnamoyl-13-decanoyl phorbol derivatives stood out,demonstrating remarkable anti-HIV-1 activities and inhibitory effects on syncytia formation.These derivatives exhibited a higher safety index compared with the positive control drug.Among them,12-(trans-4-fluorocinnamoyl)-13-decanoyl phorbol,designated as compound 3c,exhibited the most potent anti-HIV-1 activity(EC_(50)2.9 nmol·L^(−1),CC50/EC_(50)11117.24)and significantly inhibited the formation of syncytium(EC_(50)7.0 nmol·L^(−1),CC50/EC_(50)4891.43).Moreover,compound 3c is hypothesized to act both as an HIV-1 entry inhibitor and as an HIV-1 reverse transcriptase inhibitor.Isothermal titration calorimetry and molecular docking studies indicated that compound 3c may also function as a natural activator of protein kinase C(PKC).Therefore,compound 3c emerges as a potential candidate for developing new anti-HIV drugs.

Tankyrase1、TRF1及hTERT在肝细胞癌中的表达及意义

目的检测端锚聚合酶1（Tankyrose1）、端粒重复序列结合因子1（TRF1）及端粒酶逆转录酶（hTERT）mRNA在肝细胞癌（HCC）组织中的表达，探讨其在肝癌发生过程中的作用及其临床意义。方法应用RT—PCR技术对30例HCC及癌旁组织中Tankyrase1 、TRF1及hTERT mRNA的表达水平进行检测，分析其表达与HCC临床病理特征的关系。结果HCC组织中Tankyrose1及hTERT mRNA表达相对强度明显高于癌旁组织（P〈0．05）；TRF1在肝癌组织中的表达相对强度明显低于癌旁组织（P〈0．05）；HCC组织中Tankyrase1及TRF1表达与年龄、性别、肝硬化、HbsAg（＋）、肿瘤大小、肿瘤个数、术前Child-Pugh分级、TNM分期、Edmondson分级和血清AFP值均无显著相关（P〉0．05）；在HCC中Tankyrase1 mRNA和hTERT mRNA的表达呈正相关（r=0．519），Tankyrase1与TRF1 mRNA表达呈负相关（r=-0．395），TRF1 mRNA和hTERT mRNA表达呈负相关（r=-0．472）。结论HCC中Tankyrase1表达增加和TRF1表达下降可能是hTERT表达增加的原因之一，其对肝癌的发生可能起重要作用。

Steered molecular dynamics simulations of protein-ligand interactions

Studies of protein-ligand interactions are helpful to elucidating the mechanisms of ligands, providing clues for rational drug design. The currently developed steered molecular dy- namics (SMD) is a complementary approach to experimental techniques in investigating the biochemical processes occurring at microsecond or second time scale, thus SMD may provide dynamical and kinetic processes of ligand-receptor binding and unbinding, which cannot be ac- cessed by the experimental methods. In this article, the methodology of SMD is described, and the applications of SMD simulations for obtaining dynamic insights into protein-ligand interactions are illustrated through two of our own examples. One is associated with the simulations of bind- ing and unbinding processes between huperzine A and acetylcholinesterase, and the other is concerned with the unbinding process of α-APAfrom HIV-1 reverse transcriptase.

The capsid revolution

Lenacapavir,targeting the human immunodeficiency virus type-1(HIV-1)capsid,is the first-in-class antiretroviral drug recently approved for clinical use.The development of Lenacapavir is attributed to the remarkable progress in our understanding of the capsid protein made during the last few years.Considered little more than a component of the virus shell to be shed early during infection,the capsid has been found to be a key player in the HIV-1 life cycle by interacting with multiple host factors,entering the nucleus,and directing integration.Here,we describe the key advances that led to this‘capsid revolution’.