Biology subjects

Salerno, A.

Publications and source records attributed to Salerno, A..

3 recordsLinked to original sources

bioRxiv2025

Linker-rigidified VHL homodimerizers convert degraders into stabilizers of non-ubiquitinable ternary complexes

Protein degraders recruit E3 ligases to targets for ubiquitination and subsequent proteasomal degradation. Efficient degradation typically correlates with long-lived ternary complexes that position target lysines for productive ubiquitination. Here, we determine a cryo-EM structure of the Cullin 2 RING VHL (CRL2VHL) ligase dimerized by the VHL homo-PROTAC CM11, wherein one CRLVHL acts as the ligase and a second VHL as the neo-substrate. Guided by this structure, we design side-by-side, linker-rigidified VHL homodimerizers that bias the relative VHL orientation away from the E2[~]Ub active site, contrasting the flexible, head-to-head PEG linkage of CM11. Biophysical binding and in vitro ubiquitination assays show that these compounds form stable, long-lived and compact ternary complexes that are incompatible with VHL cross-ubiquitination. In cells, the compounds stabilize VHL and concomitantly inhibit it to elevate HIF-1 levels. Thus, a stable ternary complex can be non-productive for ubiquitination, and linker architecture can reprogram degraders into stabilizers by controlling target ubiquitinability.

biochemistry↗

bioRxiv2024

Do you see what I see? Diffusion imaging protocol heterogeneity biases ischemic core volume, location, and clinical associations in acute stroke

PurposeDiffusion-weighted magnetic resonance imaging (DWI) is essential for diagnosing ischemic stroke and identifying targets for emergency revascularization. Apparent diffusion coefficient (ADC) maps derived from DWI are commonly used to locate the infarct core, but they are not strictly quantitative and can vary across platforms and sites due to technical factors. This retrospective study was conducted to examine how differences in ADC map generation, resulting from varied protocols across platforms and sites, affect the determination of infarct core size, location, and related clinical outcomes in acute stroke. MethodsIn this retrospective study, 726 acute anterior circulation stroke patients admitted to the Lausanne University Hospital between May 2018 and January 2021 were selected. DWI data were used to generate ADC maps as they would appear from different protocols: two simulated with low and medium angular resolution (4 and 12 diffusion gradient directions) and one with high angular resolution (20 directions). Using a DEFUSE like criteria and image post-processing, ischemic cores were localized; core volume, location, and associations to National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) scores were compared between the two imaging sequences. ResultsSignificant differences were observed in the ADC distribution within white matter, particularly in the kurtosis and skewness, with the segmented infarct core volume being higher in protocols with reduced angular resolution compared to the 20-directions data (7.63 ml vs. 3.78 ml). The volumetric differences persisted after correcting for age, sex, and type of intervention. Infarcted voxels locations varied significantly between the two protocols. This variability affected associations between infarct core volume and clinical scores, with lower associations observed for 4-directions data compared to 20-directions data for NIHSS at admission and after 24 hours, and mRS after 3 months, further confirmed by multivariate regression. ConclusionsImaging protocol heterogeneity leads to significant changes in the ADC distribution, ischemic core location, size, and association with clinical scores. Work is needed in standardizing imaging protocols to improve the reliability of ADC as an imaging biomarker in stroke management.protocols to improve the reliability of ADC as an imaging biomarker in stroke management. Key ResultsO_LIOrientation changes in diffusion imaging significantly impact ADC distribution and threshold-based infarct core volume determination, affecting multi-centric studies. C_LIO_LILower number of directions in DWI acquisitions weakens associations between infarct volume measurements and clinical scores. C_LIO_LIFindings emphasize the impact of DWI acquisition protocol heterogeneity and image processing on acute stroke workups. C_LI

neuroscience↗

bioRxiv2020

Effectiveness of Growth Hormone Releasing Hormone Agonists (GHRH A) in Chronic Kidney Disease Induced Heart Failure with Preserved Ejection Fraction

BackgroundTherapies that improve morbidity and mortality in heart failure with preserved ejection fraction (HFpEF) are lacking. Growth hormone releasing hormone analogues (GHRH-A) reverse fibrosis and improve cardiac function in ischemic and non-ischemic animal models. We tested the hypothesis that GHRH-A treatment ameliorates chronic kidney disease (CKD)-induced HFpEF in a large animal model. MethodsFemale Yorkshire pigs (n=16) underwent 5/6 nephrectomy via renal artery embolization, which induced HFpEF, and 12-weeks later received daily subcutaneous injections of GHRH-A (n=8) or placebo (n=8). Kidney function, renal and cardiac MRI, pressure-volume loops, and electrical stimulation were assessed at baseline, 12-weeks, and 16-18 weeks post-embolization. ResultsThe CKD model was confirmed by increased creatinine and BUN. HFpEF was demonstrated at 12 weeks by maintenance of ejection fraction associated with increased left ventricular mass, relative wall thickening, end-diastolic pressure (EDP), end-diastolic pressure-volume relationship (EDPVR), and tau. After 6 weeks of treatment, diastolic function improved in the GHRH-A group, evidenced by normalization of EDP (p=0.03) associated with improved diastolic compliance as measured by EDP/EDV ratio (p=0.018). ConclusionA beneficial effect of GHRH-A in diastolic function was observed in a CKD large animal model that manifests the characteristics of HFpEF. These findings have important therapeutic implications for the HFpEF syndrome.

physiology↗