Biology subjects

Tessier, A.

Publications and source records attributed to Tessier, A..

3 recordsLinked to original sources

bioRxiv2023

Optical control of cardiac rhythm by in vivo photoactivation of an ERG channel peptide inhibitor

RATIONALECardiac rhythm, conduction and synchronization of electrical activity require the coordinated action of different types of ion channels that differ according to transmural and regional specificities. Classical pharmacology affects these ion channels in a non-regionalized way which explains why treating arrhythmias, that often occur in specific foci, has often limited efficacy in addition to negative side-effects on non-targeted organs. Photopharmacology is an emergent technology that has the potential to counteract all the negative aspects of classical pharmacology by restricting drug activity in a spatio-temporal manner. OBJECTIVEWe tested the potential of photopharmacology in specifically regulating heart activity by using a caged derivative of a natural peptide inhibitor of the ERG channel, BeKm1. The peptide was uncaged and activity monitored in vitro on a cell line expressing the hERG channel, on human cardiomyocytes derived from iPS cells, and ex vivo and in vivo on zebrafish larvae and rat hearts. METHODS AND RESULTSCaged BeKm-1 is inactive and fully active upon uncaging. Uncaging of the peptide on human iPS-derived cardiomyocytes enlarges the action potential duration and triggers arrhythmias. Uncaging also triggers bradycardia and disturbs cardiac conduction within the atria in perfused rat hearts upon illumination. The potency of photopharmacology for cardiac electrical modulation was further validated in zebrafish larvae where illumination of the caged compound induces bradycardia and atrio-ventricular desynchrony. Finally, in anesthetized rats, illumination of the caged peptide in the right atria, containing the sino-atrial node, leads to bradycardia without arrhythmia. CONCLUSIONSThis report demonstrates that photopharmacology, using the caged peptide strategy, can be used for dynamically regulating cardiac electrical activity in vivo and that spatial illumination restriction can dissociate the bradycardic effect from the arrhythmic one. The technology is applicable to all kinds of cardiac ion channels and regions of interest to create arrhythmogenic models or investigate new clinical applications.

pharmacology and toxicology↗

bioRxiv2022

Production of recombinant heterotrimeric mini-procollagen I and homotrimeric II mini-procollagen II reveals new cleavage sites for BMP-1

The proteolytic conversion of soluble procollagens into mature collagen monomers is a critical step to decrease their solubility and trigger collagen fibril formation. In the case of collagens I, II and III, this maturation process is driven by several extracellular metalloproteinases such as BMP-1, tolloid-like proteinases, meprin , meprin {beta}, ADAMTS-2 and ADAMTS-14 but the extensive characterization of these proteolytic events has been hampered by the lack of recombinant procollagens. We previously reported the production and partial characterization of recombinant homotrimeric proteins derived from procollagen III (mini-procollagens III) and, in this study, we describe how we have extended this previous work to the production of heterotrimeric mini-procollagen I and homotrimeric mini-procollagen II. These mini-procollagens include truncated triple helices and intact C-telopeptide and C-propeptide domains and were produced in suspension in HEK293-F cells with yields ranging from 2.5 mg/L to 10 mg/L after purification. They proved very useful tools to analyze the effect of calcium on the stability of the procollagen C-terminal region and to compare the procollagen C-proteinase activity of BMP-1 on the three major fibrillar procollagens or their ability to interact with various partners such as PCPE-1. Using mass spectrometry to map BMP-1 cleavage sites on the mini-procollagens, we confirmed all previously described sites but also revealed two additional cleavage sites in the 1 chain of procollagens I and II. This result shows that the mini-procollagen toolkit offers a broad range of perspectives to make functional studies but also possibly structural analyses or to develop drug screening assays.

biochemistry↗

bioRxiv2022

MHC-II expressing neutrophils circulate in blood and milk during mastitis and show high microbicidal activity

Bovine mastitis are mainly caused by bacterial infection. They are responsible for economic losses and have an impact on the health and welfare of animals. The increase in the somatic cell count in milk during mastitis is mainly due to the influx of neutrophils which have a crucial role in the elimination of pathogens. For a long time, these first line defenders has been view as microbes killers with limited role in the orchestration of the immune response. However, their role is more complex and we recently characterized a MHC-II expressing neutrophil subset with regulatory capacities in cattle. In this study, we questioned the implication of different neutrophils subsets in the mammary gland immunity during clinical and subclinical mastitis. Here, we described for the first time that, in blood as in milk, neutrophils are a heterogeneous population and encompass at least two subsets distinguishable with their expression of MHC-II. We observed higher bactericidal capacities of milk MHC-IIpos neutrophils as compared to their classical counterparts, due to a higher production of ROS and phagocytosis ability. MHC-IIpos neutrophils are enriched in milk during a subclinical mastitis as compared to blood. Moreover, we observed a positive and highly significant correlation between MHC-IIpos neutrophils and T lymphocytes present in milk during subclinical mastitis. To conclude, our study could open the way to the discovery of new biomarkers of mastitis inflammation.

immunology↗