SKP1-CUL1-F-box protein (SCF) ubiquitin ligases are versatile protein complexes that mediate the ubiquitination of protein substrates. The direct substrate recognition relies on a large family of F-box-domain-containing subunits. One of these substrate receptors is FBXO38, which is encoded by a gene found mutated in families with early-onset distal motor neuronopathy. SCFFBXO38 ubiquitin ligase controls the stability of ZXDB, a nuclear factor associated with the centromeric chromatin protein CENP-B. Loss of FBXO38 in mice results in growth retardation and defects in spermatogenesis characterized by deregulation of the Sertoli cell transcription program and compromised centromere integrity. Moreover, it was reported that SCFFBXO38 mediates the degradation of PD-1, a key immune-checkpoint inhibitor in T cells. Here, we have re-addressed the link between SCFFBXO38 and PD-1 proteolysis. Our data do not support the notion that SCFFBXO38 directly or indirectly controls the abundance and stability of PD-1 in T cells.

• Klíčová slova
• Cullin, FBXO38, Immune Checkpoint, PD-1, Protein Degradation,
• MeSH
• antigeny CD279 * metabolismus   genetika   MeSH
• F-box proteiny * metabolismus   genetika   MeSH
• lidé MeSH
• myši MeSH
• proteinligasy komplexu SCF metabolismus   genetika   MeSH
• proteolýza MeSH
• T-lymfocyty metabolismus   MeSH
• ubikvitinace MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antigeny CD279 * MeSH
• F-box proteiny * MeSH
• Fbxo38 protein, mouse MeSH Prohlížeč
• Pdcd1 protein, mouse MeSH Prohlížeč
• proteinligasy komplexu SCF MeSH

CIP/KIP and INK4 families of Cyclin-dependent kinase inhibitors (CKIs) are well-established cell cycle regulatory proteins whose canonical function is binding to Cyclin-CDK complexes and altering their function. Initial experiments showed that these proteins negatively regulate cell cycle progression and thus are tumor suppressors in the context of molecular oncology. However, expanded research into the functions of these proteins showed that most of them have non-canonical functions, both cell cycle-dependent and independent, and can even act as tumor enhancers depending on their posttranslational modifications, subcellular localization, and cell state context. This review aims to provide an overview of canonical as well as non-canonical functions of CIP/KIP and INK4 families of CKIs, discuss the potential avenues to promote their tumor suppressor functions instead of tumor enhancing ones, and how they could be utilized to design improved treatment regimens for cancer patients.

• Klíčová slova
• CIP/KIP, Cancer, Cyclin-dependent kinase inhibitors, INK4, Oncogenic signaling, Posttranslational modification, Therapy,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

The Wnt, TGF-β, and Notch signaling pathways are essential for the regulation of cellular polarity, differentiation, proliferation, and migration. Differential activation and mutual crosstalk of these pathways during animal development are crucial instructive forces in the initiation of the body axis and the development of organs and tissues. Due to the ability to initiate cell proliferation, these pathways are vulnerable to somatic mutations selectively producing cells, which ultimately slip through cellular and organismal checkpoints and develop into cancer. The architecture of the Wnt, TGF-β, and Notch signaling pathways is simple. The transmembrane receptor, activated by the extracellular stimulus, induces nuclear translocation of the transcription factor, which subsequently changes the expression of target genes. Nevertheless, these pathways are regulated by a myriad of factors involved in various feedback mechanisms or crosstalk. The most prominent group of regulators is the ubiquitin-proteasome system (UPS). To open the door to UPS-based therapeutic manipulations, a thorough understanding of these regulations at a molecular level and rigorous confirmation in vivo are required. In this quest, mouse models are exceptional and, thanks to the progress in genetic engineering, also an accessible tool. Here, we reviewed the current understanding of how the UPS regulates the Wnt, TGF-β, and Notch pathways and we summarized the knowledge gained from related mouse models.

• Klíčová slova
• cancer, gene inactivation, mouse model, ubiquitin–proteasome system,
• MeSH
• beta-katenin metabolismus   MeSH
• buněčná diferenciace fyziologie   MeSH
• homeostáza genetika   MeSH
• ligasy metabolismus   MeSH
• myši embryologie   genetika   MeSH
• proliferace buněk fyziologie   MeSH
• proteiny Wnt metabolismus   MeSH
• receptory Notch metabolismus   MeSH
• signální dráha Wnt fyziologie   MeSH
• transformující růstový faktor beta metabolismus   MeSH
• transkripční faktory metabolismus   MeSH
• ubikvitin metabolismus   MeSH
• ubikvitinligasy metabolismus   fyziologie   MeSH
• vývojová regulace genové exprese genetika   MeSH
• zvířata MeSH
• Check Tag
• myši embryologie   genetika   MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• beta-katenin MeSH
• ligasy MeSH
• proteiny Wnt MeSH
• receptory Notch MeSH
• transformující růstový faktor beta MeSH
• transkripční faktory MeSH
• ubikvitin MeSH
• ubikvitinligasy MeSH

BACKGROUND: Hypoxia can halt cell cycle progression of several cell types at the G1/S interface. The arrest needs to be overcome by cancer cells. We have previously shown that the hypoxia-inducible cellular oxygen sensor PHD3/EGLN3 enhances hypoxic cell cycle entry at the G1/S boundary. METHODS: We used PHD3 knockdown by siRNA and shRNA in HeLa and 786-0 renal cancer cells. Flow cytometry with cell synchronization was used to study cell growth at different cell cycle phases. Total and phosphospecific antibodies together with cycloheximide chase were used to study p27/CDKN1B expression and fractionations for subcellular protein localization. RESULTS: Here we show that PHD3 enhances cell cycle by decreasing the expression of the CDK inhibitor p27/CDKN1B. PHD3 reduction led to increased p27 expression under hypoxia or VHL mutation. p27 was both required and sufficient for the PHD3 knockdown induced cell cycle block. PHD3 knockdown did not affect p27 transcription and the effect was HIF-independent. In contrast, PHD3 depletion increased the p27 half-life from G0 to S-phase. PHD3 depletion led to an increase in p27 phosphorylation at serine 10 without affecting threonine phosphorylation. Intact serine 10 was required for normal hypoxic and PHD3-mediated degradation of p27. CONCLUSIONS: The data demonstrates that PHD3 can drive cell cycle entry at the G1/S transition through decreasing the half-life of p27 that occurs by attenuating p27S10 phosphorylation.

• MeSH
• buněčný cyklus genetika   MeSH
• fosforylace MeSH
• genový knockdown MeSH
• HeLa buňky MeSH
• hypoxie buňky genetika   MeSH
• inhibitor p27 cyklin-dependentní kinasy biosyntéza   genetika   MeSH
• karcinom genetika   patologie   MeSH
• kontrolní body fáze G1 buněčného cyklu genetika   MeSH
• lidé MeSH
• malá interferující RNA MeSH
• prolyl-4-hydroxylasy HIF antagonisté a inhibitory   genetika   MeSH
• regulace genové exprese u nádorů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• CDKN1B protein, human MeSH Prohlížeč
• EGLN3 protein, human MeSH Prohlížeč
• inhibitor p27 cyklin-dependentní kinasy MeSH
• malá interferující RNA MeSH
• prolyl-4-hydroxylasy HIF MeSH

Cellular and molecular pathways link thrombosis and innate immune system during sepsis. Extrinsic pathway activation of protease thrombin through FVIIa and tissue factor (TF) in sepsis help activate its endothelial cell (EC) membrane Protease Activated Receptor 1 (PAR-1). Thrombin adjusts the EC cycle through activation of G proteins (G12/13), and later through Rho GEFs (guanine nucleotide exchange factors), and provides a path for Rho GTPases mediated cytoskeletal responses involved in shape change and permeability of the EC membrane leading to an increase of leakage of plasma proteins.At the same time, thrombin stimulates spontaneous mitogenesis by inducing activation of the cell cycle from G0-G1 to S by down-regulation of p27Kip1, a negative regulator of the cell cycle, in association with the up-regulation of S-phase kinase associated protein 2 (Skp2). After transport in cytoplasm, p27 Kip1 binds to RhoA thus prevent activation of RhoA by GEFs, thus inhibit GDP-GTP exchange mediated by GEFs. In cytoplasm, releasing factor (RF) p27-RF-Rho is able to free RhoA. P27 RF-Rho binds p27kip1 and prevents p27kip1 from binding to RhoA. Exposed RhoA is later able to increase the expression of the F-box protein Skp2, after its Akt triggered 14-3-3-β-dependent cytoplasm relocation. Skp2 increases cytoplasm ubiquitination-dependent degradation of p27Kip1. Additionally, after septic induction of canonical NF-kB pathway in EC through TLR4/IRAK4/TRAF/IkB, an IKKα dimer phosphorylates the p52 precursor NF-kB2/p100, leading to p100 processing and translocation of RelB/p52 to the nucleus. By controlling the NF-kB-RelB complex, IKKα signaling regulates the transcription of the Skp2 and correspondingly p27Kip1.

• Klíčová slova
• Cell Cycle, Inherited Immune System, PAR, TLR, Thrombin,
• Publikační typ
• časopisecké články MeSH

DNA lesions trigger the DNA damage response (DDR) machinery, which protects genomic integrity and sustains cellular survival. Increasing data underline the significance of the integrity of the DDR pathway in chemotherapy response. According to a recent work, persistent exposure of A549 lung carcinoma cells to doxorubicin induces an initial DDR-dependent checkpoint response, followed by a later DDR-independent, but p27(Kip1)-dependent one. Prompted by the above report and to better understand the involvement of the DDR signaling after chemotherapeutic stress, we examined the potential role of the canonical DDR pathway in A549 cells treated with doxorubicin. Exposure of A549 cells, prior to doxorubicin treatment, to ATM, ATR and DNA-PKcs inhibitors either alone or in various combinations, revealed that the earlier documented two-step response was DDR-dependent in both steps. Notably, inhibition of both ATM and ATR or selective inhibition of ATM or DNA-PKcs resulted in cell-cycle re-entry despite the increased levels of p27(Kip1) at all time points analyzed. We further investigated the regulation of p27(Kip1) protein levels in the particular setting. Our results showed that the protein status of p27(Kip1) is mainly determined by p38-MAPK, whereas the role of SKP2 is less significant in the doxoroubicin-treated A549 cells. Cumulatively, we provide evidence that the DNA damage signaling is responsible for the prolonged cell cycle arrest observed after persistent chemotherapy-induced genotoxic stress. In conclusion, precise identification of the molecular mechanisms that are activated during the chemotherapeutic cycles could potentially increase the sensitization to the therapy applied.

• Klíčová slova
• ATM, ATR, DNA damage response, DNA-PKcs, SKP2, cell cycle arrest, chemotherapy, p27Kip1, p38-MAPK,
• MeSH
• ATM protein antagonisté a inhibitory   MeSH
• buňky A549 MeSH
• chromony farmakologie   MeSH
• doxorubicin farmakologie   MeSH
• inhibitor p27 cyklin-dependentní kinasy fyziologie   MeSH
• kofein farmakologie   MeSH
• kontrolní body fáze G2 buněčného cyklu účinky léků   MeSH
• lidé MeSH
• mitogenem aktivované proteinkinasy p38 metabolismus   MeSH
• morfoliny farmakologie   MeSH
• poškození DNA MeSH
• proteinkinasa aktivovaná DNA antagonisté a inhibitory   MeSH
• proteiny asociované s kinázou S-fáze metabolismus   MeSH
• protinádorové látky farmakologie   MeSH
• pyrony farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one MeSH Prohlížeč
• 8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one MeSH Prohlížeč
• ATM protein, human MeSH Prohlížeč
• ATM protein MeSH
• CDKN1B protein, human MeSH Prohlížeč
• chromony MeSH
• doxorubicin MeSH
• inhibitor p27 cyklin-dependentní kinasy MeSH
• kofein MeSH
• mitogenem aktivované proteinkinasy p38 MeSH
• morfoliny MeSH
• proteinkinasa aktivovaná DNA MeSH
• proteiny asociované s kinázou S-fáze MeSH
• protinádorové látky MeSH
• pyrony MeSH