Epigenetic engineering shows H3K4me2 is required for HJURP targeting and CENP-A assembly on a synthetic human kinetochore

Kinetochores assemble on distinct 'centrochromatin' containing the histone H3 variant CENP-A and interspersed nucleosomes dimethylated on H3K4 (H3K4me2). Little is known about how the chromatin environment at active centromeres governs centromeric structure and function. Here, we report that centrochromatin resembles K4-K36 domains found in the body of some actively transcribed housekeeping genes. By tethering the lysine-specific demethylase 1 (LSD1), we specifically depleted H3K4me2, a modification thought to have a role in transcriptional memory, from the kinetochore of a synthetic human artificial chromosome (HAC). H3K4me2 depletion caused kinetochores to suffer a rapid loss of transcription of the underlying α-satellite DNA and to no longer efficiently recruit HJURP, the CENP-A chaperone. Kinetochores depleted of H3K4me2 remained functional in the short term, but were defective in incorporation of CENP-A, and were gradually inactivated. Our data provide a functional link between the centromeric chromatin, α-satellite transcription, maintenance of CENP-A levels and kinetochore stability.

A national e-Delphi towards the measurement of safe medication practices in Portuguese hospitals

Objectives To determine the face and content validity of items for measuring safe medication practices in Portuguese hospitals. Methods 128 items were drafted from content analysis of existing questionnaires and the literature, employing preferred terms of the WHO International Classification for Patient Safety (Portuguese version). A two-round e-Delphi was convened, using a purposive multidisciplinary panel. Hospital-based experts were asked to rate the relevance of items on a 7-point Likert scale and to comment on their clarity and completeness. Results The response rate was similar in both rounds (70.3% and 73.4%, respectively). In the first round 91/128 (71.1%) items reached the predefined level of positive consensus. In the second round 23 additional items reached positive consensus, as well as seven items newly derived by the panel. Conclusions Most items have face and content validity, indicating relevance and clarity, and can be included in a future questionnaire for measuring safe medication practices in Portuguese hospitals.