Proteomic and 3D structure analyses highlight the C/D box snoRNP assembly mechanism and its control

International audienceIn vitro, assembly of box C/D small nucleolar ribonucleoproteins (snoRNPs) involves the sequential recruitment of core proteins to snoRNAs. In vivo, however, assembly factors are required (NUFIP, BCD1, and the FISP90-R2TP complex), and it is unknown whether a similar sequential scheme applies. In this paper, we describe systematic quantitative stable isotope labeling by amino acids in cell culture proteomic experiments and the crystal structure of the core protein Snu 13p/15.5K bound to a fragment of the assembly factor Rsa1p/NUFIP. This revealed several unexpected features: (a) the existence of a protein-only pre-snoRNP complex containing five assembly factors and two core proteins, 15.5K and Nop58; (b) the characterization of ZNHIT3, which is present in the protein-only complex but gets released upon binding to C/D snoRNAs; (c) the dynamics of the R2TP complex, which,appears a to load/unload RuvBL AAA(+) adenosine triphosphatase from pre-snoRNPs; and (d) a potential mechanism for preventing premature activation of snoRNP catalytic activity. These data provide a framework for understanding the assembly of box C/D snoRNPs

A pilot phase II randomized, cross-over, double-blinded, controlled efficacy study of ocreatide versus hyoscine hydrobromide for control of noisy breathing at the end-of-life

Noisy breathing at the end of life (noisy breathing (“NB”) occurs in up to 90% of people. Interventions have not been systematically evaluated. There has been clinical observation coupled with a proposed mechanism of effect that supports a role for octreotide in management of NB. The aim of this phase II study was to assess ten completed participants for the feasibility of an adequately powered phase III study. This randomized, double-blind, crossover pilot trial recruited participants from an inpatient palliative unit. Participants while well and their proxies simultaneously provided written informed consent. If NB were encountered, people were randomized to 200 mcg octreotide or 400 mcg hyoscine hydrobromide subcutaneously. If subsequent treatment was needed, the other medication was administered. A five point categorical scale documented the nurses\u27 assessment of secretions over six hours. Eighty participants were consented of whom 10 (3 females, 7 males; median age 79, all with advanced cancer) received medication, five in each arm. There was no difference in the median time to administration of the second medication (3 hours). Two participants in each arm had a 2 category reduction of intensity after the second medication. Although feasible to consent and study this population in a way that respects autonomy and dignity even in the terminal hours of life, this pilot study suggests reconsideration of the pharmacological interventions (choice of agents, dosing, timing of dosing and pharmacokinetic profiles), standardizing of non-pharmacological care; and ways to measure directly family distress before further randomized studies for this symptom