The human RIF1 protein controls DNA replication, but the molecular mechanism is largely unknown. Here, we demonstrate that human RIF1 negatively regulates DNA replication by forming a complex with protein phosphatase 1 (PP1) that limits phosphorylation‐mediated activation of the MCM replicative helicase. We identify specific residues on four MCM helicase subunits that show hyperphosphorylation upon RIF1 depletion, with the regulatory N‐terminal domain of MCM4 being particularly strongly affected. In addition to this role in limiting origin activation, we discover an unexpected new role for human RIF1‐PP1 in mediating efficient origin licensing. Specifically, during the G1 phase of the cell cycle, RIF1‐PP1 protects the origin‐binding ORC1 protein from untimely phosphorylation and consequent degradation by the proteasome. Depletion of RIF1 or inhibition of PP1 destabilizes ORC1, thereby reducing origin licensing. Consistent with reduced origin licensing, RIF1‐depleted cells exhibit increased spacing between active origins. Human RIF1 therefore acts as a PP1‐targeting subunit that regulates DNA replication positively by stimulating the origin licensing step, and then negatively by counteracting replication origin activation.

AimIn Japan, the do not attempt resuscitation (DNAR) order is practised routinely even though no related laws or guidelines exist. This study aimed to clarify the current status of DNAR, reveal existing DNAR‐related issues, and improve the application of DNAR.MethodsA questionnaire survey of medical institutions in Kanagawa Prefecture (total population, 9,120,000) about the current status of DNAR was carried out.ResultsThe results showed that DNAR has been practised at approximately 90% of the hospitals surveyed, but only about 30% have developed in‐hospital DNAR guidelines. Approximately 80% of the hospitals do not involve patients in the decision on their own DNAR orders. Because the DNAR order has not been legislated, it is often unclear whether to resuscitate patients when a request for an ambulance is made for a cardiac arrest at home.ConclusionIt is necessary for prefectures, municipalities, and local medical control authorities to take the initiative in establishing an ordinance on DNAR orders and developing guidelines.

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