Project description:Acquisition of multicellularity is a central event in the evolution of Eukaryota. Strikingly, animal multicellularity coincides with the emergence of three intercellular communication pathways - Notch, TGF-? and Wnt - all considered as hallmarks of metazoan development. By investigating Oopsacas minuta and Aphrocallistes vastus, we show here that the emergence of a syncytium and plugged junctions in glass sponges coincides with the loss of essential components of the Wnt signaling (i.e. Wntless, Wnt ligands and Disheveled), whereas core components of the TGF-? and Notch modules appear unaffected. This suggests that Wnt signaling is not essential for cell differentiation, polarity and morphogenesis in glass sponges. Beyond providing a comparative study of key developmental toolkits, we define here the first case of a metazoan phylum that maintained a level of complexity similar to its relatives despite molecular degeneration of Wnt pathways.
Project description:Over 600 million years ago, animals evolved from a unicellular or colonial organism whose cell(s) captured bacteria with a collar complex, a flagellum surrounded by a microvillar collar. Using principles from evolutionary cell biology, we reason that the transition to multicellularity required modification of pre-existing mechanisms for extracellular matrix synthesis and cytokinesis. We discuss two hypotheses for the origin of animal cell types: division of labor from ancient plurifunctional cells and conversion of temporally alternating phenotypes into spatially juxtaposed cell types. Mechanistic studies in diverse animals and their relatives promise to deepen our understanding of animal origins and cell biology.
Project description:Cyclin-dependant kinases play a central role in coordinating cell growth and division, and in sustaining proliferation of cancer cells, thereby constituting attractive pharmacological targets. However, there are no direct means of assessing their relative abundance in living cells, current approaches being limited to antigenic and proteomic analysis of fixed cells. In order to probe the relative abundance of these kinases directly in living cells, we have developed a fluorescent peptide biosensor with biligand affinity for CDKs and cyclins in vitro, that retains endogenous CDK/cyclin complexes from cell extracts, and that bears an environmentally-sensitive probe, whose fluorescence increases in a sensitive fashion upon recognition of its targets. CDKSENS was introduced into living cells, through complexation with the cell-penetrating carrier CADY2 and applied to assess the relative abundance of CDK/Cyclins through fluorescence imaging and ratiometric quantification. This peptide biosensor technology affords direct and sensitive readout of CDK/cyclin complex levels, and reports on differences in complex formation when tampering with a single CDK or cyclin. CDKSENS further allows for detection of differences between different healthy and cancer cell lines, thereby enabling to distinguish cells that express high levels of these heterodimeric kinases, from cells that present decreased or defective assemblies. This fluorescent biosensor technology provides information on the overall status of CDK/Cyclin complexes which cannot be obtained through antigenic detection of individual subunits, in a non-invasive fashion which does not require cell fixation or extraction procedures. As such it provides promising perspectives for monitoring the response to therapeutics that affect CDK/Cyclin abundance, for cell-based drug discovery strategies and fluorescence-based cancer diagnostics.
Project description:Several cyclin-dependent kinases (CDKs) are known to have roles in transcriptional regulation. The datasets presented here are ChIP-seq experiments for different CDKs and RNA polymerase II in murine embryonic stem cells and Jurkat cells. ChIP-Seq of cyclin-dependent kinases in mouse embryonic stem cells and Jurkat human T cell acute lymphoblastic leukemia cell line
Project description:The evolution of multicellular animals (i.e. metazoans) from a unicellular ancestor is one of the most important yet least understood evolutionary transitions. Historically, given its indispensable functions in intercellular communication and exclusive presence in metazoans, phosphotyrosine (pTyr) signalling was considered a metazoan-specific evolutionary innovation that might have contributed to the origin of metazoan multicellularity. However, recent studies have led to a new understanding of pTyr signalling evolution and its role in the metazoan origin. Sequence analyses have unravelled a much earlier emergence of pTyr signalling in eukaryotic evolution. Even so, several distinct properties of holozoan pTyr signalling may have paved the way for a hypothesized functional transition of pTyr signalling at the multicellular origin, from environmental sensing to intercellular communication, and for it to evolve as a powerful intercellular signalling system for multicellularity. Biochemical analyses of premetazoan pTyr signalling components have further revealed the premetazoan origin of many key features of metazoan pTyr signalling, and the metazoan establishment of others, including the Csk-mediated negative regulation of the activity of Src, a conserved tyrosine kinase in the Holozoa. Finally, potential future directions are discussed, with a stress on the biological functions of premetazoan pTyr signalling via newly developed gene manipulation tools in non-animal holozoans.
Project description:Cyclin-dependent kinases (CDKs) are protein kinases characterized by needing a separate subunit - a cyclin - that provides domains essential for enzymatic activity. CDKs play important roles in the control of cell division and modulate transcription in response to several extra- and intracellular cues. The evolutionary expansion of the CDK family in mammals led to the division of CDKs into three cell-cycle-related subfamilies (Cdk1, Cdk4 and Cdk5) and five transcriptional subfamilies (Cdk7, Cdk8, Cdk9, Cdk11 and Cdk20). Unlike the prototypical Cdc28 kinase of budding yeast, most of these CDKs bind one or a few cyclins, consistent with functional specialization during evolution. This review summarizes how, although CDKs are traditionally separated into cell-cycle or transcriptional CDKs, these activities are frequently combined in many family members. Not surprisingly, deregulation of this family of proteins is a hallmark of several diseases, including cancer, and drug-targeted inhibition of specific members has generated very encouraging results in clinical trials.
Project description:The unicellular ancestor of animals had a complex repertoire of genes linked to multicellular processes. This suggests that changes in the regulatory genome, rather than in gene innovation, were key to the origin of animals. Here, we carry out multiple functional genomic assays in Capsaspora owczarzaki, the unicellular relative of animals with the largest known gene repertoire for transcriptional regulation. We show that changing chromatin states, differential lincRNA expression, and dynamic cis-regulatory sites are associated with life cycle transitions in Capsaspora. Moreover, we demonstrate conservation of animal developmental transcription-factor networks and extensive network interconnection in this premetazoan organism. In contrast, however, Capsaspora lacks animal promoter types, and its regulatory sites are small, proximal, and lack signatures of animal enhancers. Overall, our results indicate that the emergence of animal multicellularity was linked to a major shift in genome cis-regulatory complexity, most notably the appearance of distal enhancer regulation.
Project description:The cellular microenvironment, characterized by an extracellular matrix (ECM), played an essential role in the transition from unicellularity to multicellularity in animals (metazoans), and in the subsequent evolution of diverse animal tissues and organs. A major ECM component are members of the collagen superfamily -comprising 28 types in vertebrates - that exist in diverse supramolecular assemblies ranging from networks to fibrils. Each assembly is characterized by a hallmark feature, a protein structure called a triple helix. A current gap in knowledge is understanding the mechanisms of how the triple helix encodes and utilizes information in building scaffolds on the outside of cells. Type IV collagen, recently revealed as the evolutionarily most ancient member of the collagen superfamily, serves as an archetype for a fresh view of fundamental structural features of a triple helix that underlie the diversity of biological activities of collagens. In this Opinion, we argue that the triple helix is a protein structure of fundamental importance in building the extracellular matrix, which enabled animal multicellularity and tissue evolution.
Project description:The harnessing in clinical practice of cyclin-dependent kinases 4/6 inhibitors, namely palbociclib, ribociclib, and abemaciclib, has substantially changed the therapeutic approach for hormone receptor-positive metastatic breast cancer (BC). Phase II-III clinical trials evaluating the addition of these agents to standard endocrine therapy reported consistent improvements in response rates and progression-free survival as well as manageable toxicity profiles and excellent impact on patients' quality of life. Hence, pivotal trials provided comparable results among different cyclin-dependent kinases 4/6 inhibitors, there is an increasing interest in finding substantial differences in order to implement their use in clinical practice. The aim of this paper is to summarize the current evidences raised from preclinical and clinical studies on cyclin-dependent kinases 4/6 inhibitors in BC, focusing on differences in terms of pharmacological properties, toxicity profile, and patients' quality of life.