The concept of an “employee” in EU labor law

The article examines the problems arising from the lack of a unified conceptual apparatus at the supranational level of the EU on the example of the absence of properly fixed signs of the status of an employee, as well as signs that allow qualifying an employment relationship. The article describes the changed practice of the Court of Justice of the EU on the issue of the extension of guarantees and rights of an employee to various persons. The problems of multilevel regulation of labor relations are fully considered, taking into account a different approach to qualify labor relations in different member states and in the EU itself. English version of the article is available at URL: https://panor.ru/articles/the-concept-of-employee-in-eu-labor-law/74819.html

Cellular feedback dynamics and multilevel regulation driven by the hippo pathway

The Hippo pathway is a dynamic cellular signalling nexus that regulates differentiation and controls cell proliferation and death. If the Hippo pathway is not precisely regulated, the functionality of the upstream kinase module is impaired, which increases nuclear localisation and activity of the central effectors, the transcriptional co-regulators YAP and TAZ. Pathological YAP and TAZ hyperactivity consequently cause cancer, fibrosis and developmental defects. The Hippo pathway controls an array of fundamental cellular processes, including adhesion, migration, mitosis, polarity and secretion of a range of biologically active components. Recent studies highlight that spatio-temporal regulation of Hippo pathway components are central to precisely controlling its context-dependent dynamic activity. Several levels of feedback are integrated into the Hippo pathway, which is further synergized with interactors outside of the pathway that directly regulate specific Hippo pathway components. Likewise, Hippo core kinases also ‘moonlight’ by phosphorylating multiple substrates beyond the Hippo pathway and thereby integrates further flexibility and robustness in the cellular decision-making process. This topic is still in its infancy but promises to reveal new fundamental insights into the cellular regulation of this therapeutically important pathway. We here highlight recent advances emphasising feedback dynamics and multilevel regulation of the Hippo pathway with a focus on mitosis and cell migration, as well as discuss potential productive future research avenues that might reveal novel insights into the overall dynamics of the pathway.

Reaction Network Modeling of Complex Ecological Interactions: Endosymbiosis and Multilevel Regulation

Endosymbiosis is a type of symbiosis where one species of microscopic scale inhabits the cell of another species of a larger scale, such that the exchange of metabolic byproducts produces mutual benefit. These benefits can occur at different biological levels. For example, endosymbiosis promotes efficiency of the cell metabolism, cell replication, and the generation of a macroscopic layer that protects the organism from its predators. Therefore, modeling endosymbiosis requires a complex-systems and multilevel approach. We propose a model of endosymbiosis based on reaction networks, where species of the reaction network represent either ecological species, resources, or conditions for the ecological interactions to happen, and the endosymbiotic interaction mechanisms are represented by different sequences of reactions (processes) in the reaction network. As an example, we develop a toy model of the coral endosymbiotic interaction. The model considers two reaction networks, representing biochemical traffic and cellular proliferation levels, respectively. In addition, the model incorporates top-down and bottom-up regulation mechanisms that stabilizes the endosymbiotic interaction.

Multilevel Regulation of Peroxisomal Proteome by Post-Translational Modifications

Peroxisomes, which are ubiquitous organelles in all eukaryotes, are highly dynamic organelles that are essential for development and stress responses. Plant peroxisomes are involved in major metabolic pathways, such as fatty acid β-oxidation, photorespiration, ureide and polyamine metabolism, in the biosynthesis of jasmonic, indolacetic, and salicylic acid hormones, as well as in signaling molecules such as reactive oxygen and nitrogen species (ROS/RNS). Peroxisomes are involved in the perception of environmental changes, which is a complex process involving the regulation of gene expression and protein functionality by protein post-translational modifications (PTMs). Although there has been a growing interest in individual PTMs in peroxisomes over the last ten years, their role and cross-talk in the whole peroxisomal proteome remain unclear. This review provides up-to-date information on the function and crosstalk of the main peroxisomal PTMs. Analysis of whole peroxisomal proteomes shows that a very large number of peroxisomal proteins are targeted by multiple PTMs, which affect redox balance, photorespiration, the glyoxylate cycle, and lipid metabolism. This multilevel PTM regulation could boost the plasticity of peroxisomes and their capacity to regulate metabolism in response to environmental changes.