Higher-order assemblies of oligomeric cargo receptor complexes form the membrane scaffold of the Cvt vesicle

Selective autophagy is the mechanism by which large cargos are specifically sequestered for degradation. The structural details of cargo and receptor assembly giving rise to autophagic vesicles remain to be elucidated. We utilize the yeast cytoplasm-to-vacuole targeting (Cvt) pathway, a prototype of selective autophagy, together with a multi-scale analysis approach to study the molecular structure of Cvt vesicles. We report the oligomeric nature of the major Cvt cargo Ape1 with a combined 2.8 Å X-ray and negative stain EM structure, as well as the secondary cargo Ams1 with a 6.3 Å cryo-EM structure. We show that the major dodecameric cargo prApe1 exhibits a tendency to form higher-order chain structures that are broken upon interaction with the receptor Atg19 in vitro The stoichiometry of these cargo-receptor complexes is key to maintaining the size of the Cvt aggregate in vivo Using correlative light and electron microscopy, we further visualize key stages of Cvt vesicle biogenesis. Our findings suggest that Atg19 interaction limits Ape1 aggregate size while serving as a vehicle for vacuolar delivery of tetrameric Ams1

Nuclear migration in mammalian brain development

During development of the mammalian brain, neural stem cells divide and give rise to adult stem cells, glia and neurons, which migrate to their final locations. Nuclear migration is an important feature of neural stem cell (radial glia progenitor) proliferation and subsequent postmitotic neuronal migration. Defects in nuclear migration contribute to severe neurodevelopmental disorders such as microcephaly and lissencephaly. In this review, we address the cellular and molecular mechanisms responsible for nuclear migration during the radial glia cell cycle and postmitotic neuronal migration, with a particular focus on the role of molecular motors and cytoskeleton dynamics in regulating nuclear behavior.The authors thank Dr. Tiago Dantas and Dr. Aditi Falnikar for critical reading of the manuscript. This work was supported by grants R01 HD40182 to R.V., and the FCT MDPhD Scholarship PD/BD/113766/2015 to J.C.G

Disentangling the molecular determinants for Cenp-F localization to nuclear pores and kinetochores

International audienceCenp-F is a multifaceted protein implicated in cancer and developmental pathologies. The Cenp-F C-terminal region contains overlapping binding sites for numerous proteins that contribute to its functions throughout the cell cycle. Here, we focus on the nuclear pore protein Nup133 that interacts with Cenp-F both at nuclear pores in prophase and at kinetochores in mitosis, and on the kinase Bub1, known to contribute to Cenp-F targeting to kinetochores. By combining in silico structural modeling and yeast two-hybrid assays, we generate an interaction model between a conserved helix within the Nup133 β-propeller and a short leucine zipper-containing dimeric segment of Cenp-F. We thereby create mutants affecting the Nup133/Cenp-F interface and show that they prevent Cenp-F localization to the nuclear envelope, but not to kinetochores. Conversely, a point mutation within an adjacent leucine zipper affecting the kinetochore targeting of Cenp-F KT-core domain impairs its interaction with Bub1, but not with Nup133, identifying Bub1 as the direct KT-core binding partner of Cenp-F. Finally, we show that Cenp-E redundantly contributes together with Bub1 to the recruitment of Cenp-F to kinetochores

Renal function and peak exercise oxygen consumption in chronic heart failure with reduced left ventricular ejection fraction

Background: Chronic kidney disease is associated with sympathetic activation and muscle abnormalities, which may contribute to decreased exercise capacity. We investigated the correlation of renal function with peak exercise oxygen consumption (V˙O2) in heart failure (HF) patients. Methods and Results: We recruited 2,938 systolic HF patients who underwent clinical, laboratory, echocardiographic and cardiopulmonary exercise testing. The patients were stratified according to estimated glomerular filtration rate (eGFR). Mean follow-up was 3.7 years. The primary outcome was a composite of cardiovascular death and urgent heart transplantation at 3 years. On multivariable regression, eGFR was predictor of peakV˙O2 (P<0.0001). Other predictors were age, sex, body mass index, HF etiology, NYHA class, atrial fibrillation, resting heart rate, Btype natriuretic peptide, hemoglobin, and treatment. After adjusting for significant covariates, the hazard ratio for primary outcome associated with peakVO2 <12 ml ・ kg−1 ・ min−1 was 1.75 (95% confidence interval (CI): 1.06–2.91; P=0.0292) in patients with eGFR ≥60, 1.77 (0.87–3.61; P=0.1141) in those with eGFR of 45–59, and 2.72 (1.01– 7.37; P=0.0489) in those with eGFR <45 ml ・ min−1 ・ 1.73 m−2. The area under the receiver-operating characteristic curve for peakV˙O2 <12 ml ・ kg−1 ・ min−1 was 0.63 (95% CI: 0.54–0.71), 0.67 (0.56–0.78), and 0.57 (0.47–0.69), respectively. Testing for interaction was not significant. Conclusions: Renal dysfunction is correlated with peakV O2. A peakV O2 cutoff of 12 ml ・ kg–1 ・ min–1 offers limited prognostic information in HF patients with more severely impaired renal function

Heart failure prognosis over time: how the prognostic role of oxygen consumption and ventilatory efficiency during exercise has changed in the last 20 years

AIMS: Exercise-derived parameters, specifically peak exercise oxygen uptake (peak VO2 ) and minute ventilation/carbon dioxide relationship slope (VE/VCO2 slope), have a pivotal prognostic value in heart failure (HF). It is unknown how the prognostic threshold of peak VO2 and VE/VCO2 slope has changed over the last 20\u2009years in parallel with HF prognosis improvement. METHODS AND RESULTS: Data from 6083 HF patients (81% male, age 61\u2009\ub1\u200913\u2009years), enrolled in the MECKI score database between 1993 and 2015, were retrospectively analysed. By enrolment year, four groups were generated: group 1 1993-2000 (n\u2009=\u2009440), group 2 2001-2005 (n\u2009=\u20091288), group 3 2006-2010 (n\u2009=\u20092368), and group 4 2011-2015 (n\u2009=\u20091987). We compared the 10-year survival of groups and analysed how the overall risk (cardiovascular death, urgent heart transplantation, or left ventricular assist device implantation) changed over time according to peak VO2 and VE/VCO2 slope and to major clinical and therapeutic variables. At 10\u2009years, a progressively higher survival from group 1 to group 3 was observed, with no further improvement afterwards. A 20% risk for peak VO2 15\u2009mL/min/kg (95% confidence interval 16-13), 9 (11-8), 4 (4-2) and 5 (7-4) was observed in group 1, 2, 3, and 4, respectively, while the VE/VCO2 slope value for a 20% risk was 32 (37-29), 47 (51-43), 59 (64-55), and 57 (63-52), respectively. CONCLUSIONS: Heart failure prognosis improved over time up to 2010 in a HF population followed by experienced centres. The peak VO2 and VE/VCO2 slope cut-offs identifying a definite risk progressively decreased and increased over time, respectively. The prognostic threshold of peak VO2 and VE/VCO2 slope must be updated whenever HF prognosis improves