A TTRAP adaptor molekula szerepének vizsgálata a TGF-beta ligand család szignalizációs mechanizmusában = Role of the TTRAP adaptor molecule in the signaling mechanisms of TGF-beta family ligands

A TGF-β fehérje egy esszenciális növekedési faktor, amely fontos szabályzó szerepet tölt be a sejtek életének szinte minden mozzanatában. Mindezek mellett kiemelkedő szereppel bír a daganatos betegségek elleni védelemben is, gátolva a szervezetben a sejtek kontrollálatlan burjánzását. Tumor fejlődés során a TGF-β jelátviteli útvonal komponenseiben mutációk és epigenetikai változások halmozódnak fel, amelyek nem csak a citokin sejtosztódást gátló hatásaival szembeni rezisztencia kialakulását eredményezik, hanem gyakran paradox módon azt a tumorok progresszióját elősegítő tényezővé változtatják. Kutatásaink során ennek a fontos biológiai jelenségnek a jobb megértését tűztük célul. Figyelmüket döntően egy új adaptor fehérjére, TTRAP-re összpontosítottuk. Megállapítottuk, hogy TTRAP fontos szerepet tölt be mind a Smad függő mind a Smad független TGF-β jelátviteli folyamatokban. Kifejlesztettünk egy egér emlő epiteliáls sejtvonalon (NMuMG) alapuló modell rendszert amelynek felhasználásával bizonyítottuk, hogy a molekula fontos komponense a TGF-β indukálta programozott sejthalál (apoptózis) folyamatának. Kutatásaink a rákellenes szerek egy olyan új osztályának a kifejlesztéséhez teremthetik meg az alapot, amelyek specifikusan gátolják TGF-β tumor fejlődést elősegítő hatásait előrehaladott rák betegségekben. | TGF-β is a pleiotropic cytokine that regulates mammalian development, differentiation, and homeostasis. It is also a potent anticancer agent that prohibits the uncontrolled proliferation of epithelial, endothelial, and hematopoietic cells. Aberrations in the TGF-β pathway bring about resistance to TGF-β-mediated growth arrest and thus give rise to human malignances. Paradoxically, these genetic and epigenetic aberrations also conspire to convert TGF-β from a suppressor of tumor formation to a promoter of their growth, survival and metastasis. Our main objective was to better understand the mechanisms that underlie the ability of TGF-β to mediate tumor suppression in normal cells, and conversely, to facilitate cancer progression in malignant cells. We focused our attention on elucidating the role of the TTRAP adaptor molecule in TGF-β signaling. We have shown that TTRAP is an important component of both Smad-dependent and Smad-independent branches of TGF-β signaling. In addition, we have developed a murine mammary epithelial cell line (NMuMG) based model system for studying TTRAP's role in various TGF-β dependent biological responses. Using this model, we have demonstrated that TTRAP is a critical component of TGF-β induced apoptosis. In summary, our results may open up new avenues for developing drugs capable of selectively negating TGF-β's pro-oncogenic effects in late stage malignances

Role of SUMO modification of human PCNA at stalled replication fork

DNA double-strand breaks (DSBs) can be generated not only by reactive agents but also as a result of replication fork collapse at unrepaired DNA lesions. Whereas ubiquitylation of proliferating cell nuclear antigen (PCNA) facilitates damage bypass, modification of yeast PCNA by small ubiquitin-like modifier (SUMO) controls recombination by providing access for the Srs2 helicase to disrupt Rad51 nucleoprotein filaments. However, in human cells, the roles of PCNA SUMOylation have not been explored. Here, we characterize the modification of human PCNA by SUMO in vivo as well as in vitro. We establish that human PCNA can be SUMOylated at multiple sites including its highly conserved K164 residue and that SUMO modification is facilitated by replication factor C (RFC). We also show that expression of SUMOylation site PCNA mutants leads to increased DSB formation in the Rad18(-/-) cell line where the effect of Rad18-dependent K164 PCNA ubiquitylation can be ruled out. Moreover, expression of PCNA-SUMO1 fusion prevents DSB formation as well as inhibits recombination if replication stalls at DNA lesions. These findings suggest the importance of SUMO modification of human PCNA in preventing replication fork collapse to DSB and providing genome stability

TTRAP is a novel component of the non-canonical TRAF6-TAK1 TGF-β signaling pathway.

Transforming growth factor-β (TGF-β) principally relays its effects through the Smad pathway however, accumulating evidence indicate that alternative signaling routes are also employed by this pleiotropic cytokine. For instance recently, we have demonstrated that ligand occupied TGF-β receptors can directly trigger the TRAF6-TAK1 signaling module, resulting in MAP kinase activation. Here we report identification of the adaptor molecule TTRAP as a novel component of this non-canonical TGF-β pathway. We show that the protein associates with TGF-β receptors and components of the TRAF6-TAK1 signaling module, resulting in differential regulation of TGF-β activated p38 and NF-κB responses. Modulation of cellular TTRAP level affects cell viability in the presence of TGF-β, suggesting that the protein is an important component of the TGF-β induced apoptotic process

Functional dissection of a plant Argonaute

View of the Sanctuary of Apollo, looking northwest, as seen from The Sanctuary of Athena Pronaia; Site in Phokis in central Greece, about 165 km north-west of Athens, which flourished from the 8th century BCE to the 2nd century CE. It was one of the most important sacred sites of ancient Greece, the home of the Delphic Oracle and reputed to be the centre of the world. High in the foothills of Mt Parnassos, Delphi lies between the twin cliffs of the Phaidriades ('shining rocks'), overlooking the valley of the River Pleistos and the plain of Kirrha (now Itea) on the shores of the Gulf of Corinth. Source: Grove Art Online; http://www.groveart.com/ (accessed 12/9/2007

Abscisic Acid Connects Phytohormone Signaling with RNA Metabolic Pathways and Promotes an Antiviral Response that Is Evaded by a Self-Controlled RNA Virus

© 2020 The Authors.A complex network of cellular receptors, RNA targeting pathways, and small-molecule signaling provides robust plant immunity and tolerance to viruses. To maximize their fitness, viruses must evolve control mechanisms to balance host immune evasion and plant-damaging effects. The genus Potyvirus comprises plant viruses characterized by RNA genomes that encode large polyproteins led by the P1 protease. A P1 autoinhibitory domain controls polyprotein processing, the release of a downstream functional RNA-silencing suppressor, and viral replication. Here, we show that P1Pro, a plum pox virus clone that lacks the P1 autoinhibitory domain, triggers complex reprogramming of the host transcriptome and high levels of abscisic acid (ABA) accumulation. A meta-analysis highlighted ABA connections with host pathways known to control RNA stability, turnover, maturation, and translation. Transcriptomic changes triggered by P1Pro infection or ABA showed similarities in host RNA abundance and diversity. Genetic and hormone treatment assays showed that ABA promotes plant resistance to potyviral infection. Finally, quantitative mathematical modeling of viral replication in the presence of defense pathways supported self-control of polyprotein processing kinetics as a viral mechanism that attenuates the magnitude of the host antiviral response. Overall, our findings indicate that ABA is an active player in plant antiviral immunity, which is nonetheless evaded by a self-controlled RNA virus.Molecular networks provide robust plant immunity against pathogens, including viruses. Here, meta-analyses indicate that abscisic acid (ABA) connects hormone signaling with RNA metabolic pathways and contributes to plant antiviral immunity, which is evaded by an RNA virus with self-controlled polyprotein-processing kinetics. This study reveals a regulatory mechanism that controls viral infection dynamics and the magnitude of host antiviral responses.This work was supported by funds to J.A.G. from the Ministerio de Ciencia e Innovación (Spain), grants BIO2016-80572-R and PID2019-109380RB-I00 / AEI / 10.13039/501100011033 (AEI-FEDER). K.F. is funded by grant K124705 from the National Research Development and Innovation Office (Hungary), and S.M.-B. by grant 2017 SGR 980 from the Generalitat de Catalunya (Spain). Galaxy is a platform supported by NIH grant HG006620. F.P. was the recipient of a post-doctoral fellowship from Academia Sinica (Taiwan)