The p53 tumor suppressor is a transcription factor with roles in cell development, apoptosis, oncogenesis, aging, and homeostasis in response to stresses and infections. p53 is tightly regulated by the MDM2 E3 ubiquitin ligase. The p53-MDM2 pathway has coevolved, with MDM2 remaining largely conserved, whereas the TP53 gene morphed into various isoforms. Studies on prevertebrate ancestral homologs revealed the transition from an environmentally induced mechanism activating p53 to a tightly regulated system involving cell signaling. The evolution of this mechanism depends on structural changes in the interacting protein motifs. Elephants such as Loxodonta africana constitute ideal models to investigate this coevolution as they are large and long-living as well as having 20 copies of TP53 isoformic sequences expressing a variety of BOX-I MDM2-binding motifs. Collectively, these isoforms would enhance sensitivity to cellular stresses, such as DNA damage, presumably accounting for strong cancer defenses and other adaptations favoring healthy aging. Here we investigate the molecular evolution of the p53-MDM2 system by combining in silico modeling and in vitro assays to explore structural and functional aspects of p53 isoforms retaining the MDM2 interaction, whereas forming distinct pools of cell signaling. The methodology used demonstrates, for the first time that in silico docking simulations can be used to explore functional aspects of elephant p53 isoforms. Our observations elucidate structural and mechanistic aspects of p53 regulation, facilitate understanding of complex cell signaling, and suggest testable hypotheses of p53 evolution referencing Peto's Paradox.

• Klíčová slova
• Loxodonta africana, Peto’s Paradox, intrinsic specificity, lifespan, model, molecular evolution, p53 retrogenes, structural variations,
• MeSH
• geny p53 MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• nádory * genetika   MeSH
• protein - isoformy genetika   metabolismus   MeSH
• protoonkogenní proteiny c-mdm2 genetika   metabolismus   MeSH
• sloni * genetika   metabolismus   MeSH
• ubikvitinace MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• nádorový supresorový protein p53 MeSH
• protein - isoformy MeSH
• protoonkogenní proteiny c-mdm2 MeSH

Better understanding of GBM signalling networks in-vivo would help develop more physiologically relevant ex vivo models to support therapeutic discovery. A "functional proteomics" screen was undertaken to measure the specific activity of a set of protein kinases in a two-step cell-free biochemical assay to define dominant kinase activities to identify potentially novel drug targets that may have been overlooked in studies interrogating GBM-derived cell lines. A dominant kinase activity derived from the tumour tissue, but not patient-derived GBM stem-like cell lines, was Bruton tyrosine kinase (BTK). We demonstrate that BTK is expressed in more than one cell type within GBM tissue; SOX2-positive cells, CD163-positive cells, CD68-positive cells, and an unidentified cell population which is SOX2-negative CD163-negative and/or CD68-negative. The data provide a strategy to better mimic GBM tissue ex vivo by reconstituting more physiologically heterogeneous cell co-culture models including BTK-positive/negative cancer and immune cells. These data also have implications for the design and/or interpretation of emerging clinical trials using BTK inhibitors because BTK expression within GBM tissue was linked to longer patient survival.

• MeSH
• glioblastom enzymologie   mortalita   patologie   MeSH
• kokultivační techniky metody   MeSH
• lidé MeSH
• míra přežití MeSH
• nádorové buněčné linie MeSH
• nádorové kmenové buňky enzymologie   MeSH
• nádory mozku enzymologie   mortalita   patologie   MeSH
• proteinkinasa BTK metabolismus   MeSH
• proteom metabolismus   MeSH
• proteomika metody   MeSH
• signální transdukce * MeSH
• transkripční faktory SOXB1 metabolismus   MeSH
• viabilita buněk MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• BTK protein, human MeSH Prohlížeč
• proteinkinasa BTK MeSH
• proteom MeSH
• SOX2 protein, human MeSH Prohlížeč
• transkripční faktory SOXB1 MeSH