Binding mode of conformations and structure-based pharmacophore development for farnesyltransferase inhibitors

Farnesyltransferase (FTase) is one of the prenyltransferase family enzymes that catalyse the transfer of 15-membered isoprenoid (farnesyl) moiety to the cysteine of CAAX motif-containing proteins including Rho and Ras family of G proteins. Inhibitors of FTase act as drugs for cancer, malaria, progeria and other diseases. In the present investigation, we have developed two structure-based pharmacophore models from protein–ligand complex (3E33 and 3E37) obtained from the protein data bank. Molecular dynamics (MD) simulations were performed on the complexes, and different conformers of the same complex were generated. These conformers were undergone protein–ligand interaction fingerprint (PLIF) analysis, and the fingerprint bits have been used for structure-based pharmacophore model development. The PLIF results showed that Lys164, Tyr166, TrpB106 and TyrB361 are the major interacting residues in both the complexes. The RMSD and RMSF analyses on the MD-simulated systems showed that the absence of FPP in the complex 3E37 has significant effect in the conformational changes of the ligands. During this conformational change, some interactions between the protein and the ligands are lost, but regained after some simulations (after 2 ns). The structure-based pharmacophore models showed that the hydrophobic and acceptor contours are predominantly present in the models. The pharmacophore models were validated using reference compounds, which significantly identified as HITs with smaller RMSD values. The developed structure-based pharmacophore models are significant, and the methodology used in this study is novel from the existing methods (the original X-ray crystallographic coordination of the ligands is used for the model building). In our study, along with the original coordination of the ligand, different conformers of the same complex (protein–ligand) are used. It concluded that the developed methodology is significant for the virtual screening of novel molecules on different targets.     

Erratum to: Specific stressors in endonasal skull base surgery with and without navigation

European Archives of Oto-Rhino-Laryngology -     

甲状旁腺激素对大鼠牵张成骨过程中O NC、OPN、C-FOS、COL1、VEGF、RUNX2、ALP基因表达的影响

目的：探讨甲状旁腺激素（PTH）对大鼠牵张成骨（DO）过程中ONC、OPN、C-FOS、COL1、VEGF、RUNX2、ALP基因表达的影响。方法30只雄性大鼠制备大鼠下颌骨DO模型。随机分5组，每组6只。第1组（只有牵张无PTH），术后8周取材，应用HE染色及微CT检测，以确定成骨情况。第2组（有牵张无PTH），第3组（有牵张有PTH），第4组（无牵张有PTH），第5组（对照组：无牵张无PTH）。2、3、4组及对照组术后1周取材，RT-PCR测定ONC、OPN、C-FOS、COL1、VEGF、RUNX2、ALP基因的表达。结果第1组，新骨形成，骨质充满牵张区，骨质连续，大鼠建模成功。RT-PCR检测结果显示，2、3、4组与对照组比较，OPN、COL1、RUNX2、ALP基因表达有明显提高（P＜0．05），其中第3组最为明显。ONC、C-FOS、VEGF基因2、3、4组与对照组比较差异无统计学意义（P＞0．05）。结论 PTH在 DO 过程中，间歇性给以 PTH的作用只有在牵张期发挥作用，其对 OPN、COL1、RUNX2、ALP基因表达能够获得理想的协同作用。