Biology subjects

Rocchetti, M.

Publications and source records attributed to Rocchetti, M..

4 recordsLinked to original sources

bioRxiv2024

YAP1 Contributes to The Development of Contractile Force and Sarcomere Maturation in Human Pluripotent Stem Cell Derived Cardiomyocytes

BackgroundPerspective regenerative therapies for injured myocardium focus on reactivating developmental processes to regenerate damaged contractile tissue. In animal models, the Hippo pathway was shown to improve heart regeneration after myocardial infarction, possibly by expanding the pool of cardiomyocytes. We hypothesized that activating the Hippo pathways downstream effector, Yes Associated Protein (YAP1), may have effects beyond promoting proliferation in human cardiomyocytes. We have therefore investigated how YAP1 influences human cardiomyocyte maturation, sarcomere structure, electrophysiological properties, their response to mechanical stimuli, intracellular Ca2+'' dynamics and force development using models of cardiomyocytes derived from pluripotent stem cells. MethodsWe employed genetic models of YAP1 deficient human embryonic and induced pluripotent stem cells, cardiomyocyte differentiation, compliant cultivation substrates, mechanical actuation, ECM deposition, super resolution microscopy, electrophysiological measurements and engineered heart tissues (EHTs) to characterize the effects of YAP1 deficiency on cardiomyocytes during maturation. We also used full length YAP1 re- expression to rescue the effects of YAP1 deficiency in contracting cardiomyocytes. ResultsYAP1 contributes to cardiomyocyte maturation, participates in the formation and alignment of myofibrils, as well as in the maturation of electrophysiological properties. The net effect of YAP1 deficiency in cardiomyocytes is the inability to respond to physiological stimuli by compensatory growth resulting in reduced force development. Additionally, YAP1 reactivation in contracting cardiomyocytes leads to rescue of myofibril maturation. ConclusionsThis research demonstrates that YAP1 activity is essential to promote cardiomyocyte maturation, contractility, and response to regeneration inducing stimuli.

cell biology↗

bioRxiv2023

Batch Action PoTential Analyser (BAPTA): an open source tool for automated high throughput analysis of cardiac action potentials

The cardiac action potential (AP) is a key species-specific feature of cardiomyocytes that occurs in response to coordinated actions of ion channels. It represents the first step of the cardiac excitation-contraction coupling and it is crucial for cardiomyocyte (CM) physiology. Changes in the cardiac AP may primarily occur as a consequence of diseases or as a direct or unwanted response to drugs. Our ability to quantify these changes defines the reliability of our measurements and its throughput. Cardiac AP parameters are often quantified through manual time-consuming data analysis protocols or custom-made and proprietary data analysis pipelines; to the best of our knowledge, no tools are currently available for automated cardiac AP analysis and AP parameter quantification. Here we introduce a free and open source software tool named Batch Action PoTential Analyser (BAPTA), written in the R language, designed to i) overcome the inherent operator-dependent bias on trace selection affecting reproducibility, ii) vastly improve the throughput of the analyses of large datasets and iii) analyse both spontaneous and triggered APs from CMs of multiple species and origin. We present here four use-cases in which BAPTA can be used at high throughput to investigate the effects of: 1) a disease (cardiomyopathy) on rat CMs, 2) drugs on mouse pacemaker cells, 3) rate-dependency of AP duration in guinea pig CMs and 4) metabolic electrophysiological maturation in human stem-cell-derived CMs. Overall, BAPTA consistently provides faster, more reproducible and scalable readouts which excellently correlate with manual analyses performed by experienced electrophysiologists.

physiology↗

bioRxiv2021

Istaroxime metabolite PST3093 selectively stimulates SERCA2a and reverses disease-induced changes in cardiac function

BackgroundHeart failure (HF) therapeutic toolkit would strongly benefit from the availability of ino-lusitropic agents with a favorable pharmacodynamics and safety profile. Istaroxime is a promising agent, which combines Na+/K+ pump inhibition with SERCA2a stimulation; however, it has a very short half-life and extensive metabolism to a molecule, named PST3093. The present work aims to investigate whether PST3093, still retains the pharmacodynamic and pharmacokinetic properties of its parent compound. MethodsWe studied PST3093 for its effects on SERCA2a and Na+/K+ ATPase activities, Ca2+ dynamics in isolated myocytes and hemodynamic effects in an in-vivo rat model of diabetic (streptozotocin (STZ)-induced) cardiomyopathy. ResultsIstaroxime infusion in HF patients led to accumulation of PST3093 in the plasma; clearance was substantially slower for PST3093 than for istaroxime. In cardiac rat preparations PST3093 did not inhibit the Na+/K+ ATPase activity, but retained SERCA2a stimulatory activity. In in-vivo echocardiographic assessment, PST3093 improved overall cardiac performance and reversed most STZ-induced abnormalities. PST3093 i.v. toxicity was considerably lower than that of istaroxime and it failed to significantly interact with 50 off-targets. ConclusionsOverall, PST3093 is a "selective" SERCA2a activator, the prototype of a novel pharmacodynamic category with a potential in the ino-lusitropic approach to HF with prevailing diastolic dysfunction. Its pharmacodynamics are peculiar and its pharmacokinetics are suitable to prolong the cardiac beneficial effect of istaroxime infusion. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=137 SRC="FIGDIR/small/455204v3_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@bc9220org.highwire.dtl.DTLVardef@1d7a6eorg.highwire.dtl.DTLVardef@1510c71org.highwire.dtl.DTLVardef@7f037_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2019

Bee visitation and fruit quality in berries under protected cropping vary along the length of polytunnels

Wild and managed bees provide effective crop pollination services worldwide. Protected cropping conditions are thought to alter the ambient environmental conditions in which pollinators forage for flowers, yet few studies have compared conditions at the edges and centre of growing tunnels. We measured environmental variables (temperature, relative humidity, wind speed, white light and UV light) and surveyed the activity of managed honeybees Apis mellifera, wild stingless bees Tetragonula carbonaria and sweat bees Homalictus urbanus along the length of 32 multiple open-ended polyethylene growing tunnels. These were spaced across 12 blocks at two commercial berry farms, in Coffs Harbour, New South Wales and Walkamin, North Queensland, Australia. Berry yield, fresh weight and other quality metrics were recorded at discrete increments along the length of the tunnels. We found a higher abundance and greater number of flower visits by stingless bees and honeybees at the end of tunnels, and less frequent visits to flowers toward the middle of tunnels. The centre of tunnels experienced higher temperatures and reduced wind speed. In raspberry, fruit shape was improved with greater pollinator abundance and was susceptible to higher temperatures. In blueberry, per plant yield and mean berry weight were positively associated with pollinator abundance and were lower at the centre of tunnels than at the edge. Fruit quality (crumbliness) in raspberries was improved with a greater number of visits by sweat bees, who were not as susceptible to climatic conditions within tunnels. Understanding bee foraging behaviour and changes to yield under protected cropping conditions is critical to inform the appropriate design of polytunnels and aid pollinator management within them.

ecology↗