Predicting Inactive Conformations of Protein Kinases Using Active Structures: Conformational Selection of Type-II Inhibitors

Protein kinases have been found to possess two characteristic conformations in their activation-loops: the active DFG-in conformation and the inactive DFG-out conformation. Recently, it has been very interesting to develop type-II inhibitors which target the DFG-out conformation and are more specific than the type-I inhibitors binding to the active DFG-in conformation. However, solving crystal structures of kinases with the DFG-out conformation remains a challenge, and this seriously hampers the application of the structure-based approaches in development of novel type-II inhibitors. To overcome this limitation, here we present a computational approach for predicting the DFG-out inactive conformation using the DFG-in active structures, and develop related conformational selection protocols for the uses of the predicted DFG-out models in the binding pose prediction and virtual screening of type-II ligands. With the DFG-out models, we predicted the binding poses for known type-II inhibitors, and the results were found in good agreement with the X-ray crystal structures. We also tested the abilities of the DFG-out models to recognize their specific type-II inhibitors by screening a database of small molecules. The AUC (area under curve) results indicated that the predicted DFG-out models were selective toward their specific type-II inhibitors. Therefore, the computational approach and protocols presented in this study are very promising for the structure-based design and screening of novel type-II kinase inhibitors

Prevalence and incidence of memory complaints in employed compared to non-employed aged 55-64 years and the role of employment characteristics

Objectives: To examine the association of employment status and characteristics with prevalent and incident memory complaints (MC) in 55-64-year-olds. Methods: Subjects were participants of the Longitudinal Aging Study Amsterdam (LASA). Respondents with baseline data were selected to examine the association of employment status (n = 1525) and employment characteristics (n = 1071) with prevalent MC (i.e., MC at baseline). Respondents without MC at baseline were selected to examine the association of employment (n = 526) and employment characteristics (n = 379; working hours, job prestige, job level, psychological job demands, iso-strain) with incident MC (i.e., no MC at baseline and MC at three-year follow-up). Associations were adjusted for relevant covariates (demographics, memory performance, physical health, mental health, personality traits). Logistic regression was applied. Data were weighed according to gender and age of the Dutch population. Results: At baseline 20.5% reported MC. At three-year follow-up, 15.4% had incident MC. No associations were found between employment status and MC. Adjusted analysis revealed that individuals with high occupational cognitive demands were more likely to have prevalent MC. Conclusions: Middle-aged workers are equally as likely to experience MC as non-working age-peers. Among workers, those with cognitively demanding work were more likely to experience MC, independent of memory performance. Memory decline due to ageing may be noticed sooner in 55-64-year-olds performing cognitively demanding work