Early Devonian (Late Emsian) shark fin remains (Chondrichthyes) from the Paraná Basin, southern Brazil

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PTP-PEST controls EphA3 activation and ephrin-induced cytoskeletal remodelling

Eph receptors and their corresponding membrane-bound ephrin ligands regulate cell positioning and establish tissue patterns during embryonic and oncogenic development. Emerging evidence suggests that assembly of polymeric Eph signalling clusters relies on cytoskeletal reorganisation and underlies regulation by protein tyrosine phosphatases (PTPs). PTP-PEST (also known as PTPN12) is a central regulator of actin cytoskeletal dynamics. Here, we demonstrate that an N-terminal fragment of PTP-PEST, generated through an ephrinA5-triggered and spatially confined cleavage mediated by caspase-3, attenuates EphA3 receptor activation and its internalisation. Isolation of EphA3 receptor signalling clusters within intact plasma membrane fragments obtained by detergent-free cell fractionation reveals that stimulation of cells with ephrin triggers effective recruitment of this catalytically active truncated form of PTP-PEST together with key cytoskeletal and focal adhesion proteins. Importantly, modulation of actin polymerisation using pharmacological and dominant-negative approaches affects EphA3 phosphorylation in a similar manner to overexpression of PTP-PEST. We conclude that PTP-PEST regulates EphA3 activation both by affecting cytoskeletal remodelling and through its direct action as a PTP controlling EphA3 phosphorylation, indicating its multifaceted regulation of Eph signalling.Mariam Mansour, Eva Nievergall, Kristina Gegenbauer, Carmen Llerena, Lakmali Atapattu, Maxime Hallé, Michel L. Tremblay, Peter W. Janes, and Martin Lackman

Old and new results about relativistic Hermite polynomials

International audienceWe provide new proofs of already known results as well as new results about the family of relativistic Hermite polynomials. We use essentially probabilistic tools such as moment representations, pioneered by Ismail , but also subordination, that allows to explicit links between Gegenbauer, usual Hermite, and relativistic Hermite polynomials