A Conditional Yeast E1 Mutant Blocks the Ubiquitin–Proteasome Pathway and Reveals a Role for Ubiquitin Conjugates in Targeting Rad23 to the Proteasome

E1 ubiquitin activating enzyme catalyzes the initial step in all ubiquitin-dependent processes. We report the isolation of uba1-204, a temperature-sensitive allele of the essential Saccharomyces cerevisiae E1 gene, UBA1. Uba1-204 cells exhibit dramatic inhibition of the ubiquitin–proteasome system, resulting in rapid depletion of cellular ubiquitin conjugates and stabilization of multiple substrates. We have employed the tight phenotype of this mutant to investigate the role ubiquitin conjugates play in the dynamic interaction of the UbL/UBA adaptor proteins Rad23 and Dsk2 with the proteasome. Although proteasomes purified from mutant cells are intact and proteolytically active, they are depleted of ubiquitin conjugates, Rad23, and Dsk2. Binding of Rad23 to these proteasomes in vitro is enhanced by addition of either free or substrate-linked ubiquitin chains. Moreover, association of Rad23 with proteasomes in mutant and wild-type cells is improved upon stabilizing ubiquitin conjugates with proteasome inhibitor. We propose that recognition of polyubiquitin chains by Rad23 promotes its shuttling to the proteasome in vivo

Titration of mitochondrial fusion rescues Mff-deficient cardiomyopathy

Defects in mitochondrial fusion or fission are associated with many pathologies, raising the hope that pharmacological manipulation of mitochondrial dynamics may have therapeutic benefit. This approach assumes that organ physiology can be restored by rebalancing mitochondrial dynamics, but this concept remains to be validated. We addressed this issue by analyzing mice deficient in Mff, a protein important for mitochondrial fission. Mff mutant mice die at 13 wk as a result of severe dilated cardiomyopathy leading to heart failure. Mutant tissue showed reduced mitochondrial density and respiratory chain activity along with increased mitophagy. Remarkably, concomitant deletion of the mitochondrial fusion gene Mfn1 completely rescued heart dysfunction, life span, and respiratory chain function. Our results show for the first time that retuning the balance of mitochondrial fusion and fission can restore tissue integrity and mitochondrial physiology at the whole-organ level. Examination of liver, testis, and cerebellum suggest, however, that the precise balance point of fusion and fission is cell type specific

Achieving higher performing primary care through patient registration: A review of twelve high-income countries

Background: Patient registration with a primary care providers supports continuity in the patient-provider relationship. This paper develops a framework for analysing the characteristics of patient registration across countries; applies this framework to a selection of countries; and identifies challenges and ongoing reform efforts. Methods: 12 jurisdictions (Denmark, France, Germany, Ireland, Israel, Italy, Netherlands, Norway, Ontario [Canada], Sweden, Switzerland, United Kingdom) were selected for analysis. Information was collected by national researchers who reviewed relevant literature and policy documents to report on the establishment and evolution of patient registration, the requirements and benefits for patients, providers and payers, and its connection to primary care reforms. Results: Patient registration emerged as part of major macro-level health reforms linked to the introduction of universal health coverage. Recent reforms introduced registration with the aim of improving quality through better coordination and efficiency through reductions in unnecessary referrals. Patient registration is mandatory only in three countries. Several countries achieve high levels of registration by using strong incentives for patients and physicians (capitation payments). Conclusion: Patient registration means different things in different countries and policy-makers and researchers need to take into consideration: the history and characteristics of the registration system; the use of incentives for patients and providers; and the potential for more explicit use of patient-provider agreements as a policy to achieve more timely, appropriate, continuous and integrated care