The eIF4F translation initiation complex plays a critical role in melanoma resistance to clinical BRAF and MEK inhibitors. In this study, we uncover a function of eIF4F in the negative regulation of the rat sarcoma (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) signaling pathway. We demonstrate that eIF4F is essential for controlling ERK signaling intensity in treatment-naïve melanoma cells harboring BRAF or NRAS mutations. Specifically, the dual-specificity phosphatase DUSP6/MKP3, which acts as a negative feedback regulator of ERK activity, requires continuous production in an eIF4F-dependent manner to limit excessive ERK signaling driven by oncogenic RAF/RAS mutations. Treatment with small-molecule eIF4F inhibitors disrupts the negative feedback control of MAPK signaling, leading to ERK hyperactivation and EGR1 overexpression in melanoma cells in vitro and in vivo. Furthermore, our quantitative analyses reveal a high spare signaling capacity in the ERK pathway, suggesting that eIF4F-dependent feedback keeps the majority of ERK molecules inactive under normal conditions. Overall, our findings highlight the crucial role of eIF4F in regulating ERK signaling flux and suggest that pharmacological eIF4F inhibitors can disrupt the negative feedback control of MAPK activity in melanomas with BRAF and NRAS activating mutations.

• MeSH
• eukaryotický iniciační faktor 4F * metabolismus   genetika   MeSH
• extracelulárním signálem regulované MAP kinasy metabolismus   MeSH
• fosfatasa 6 s dvojí specificitou metabolismus   genetika   MeSH
• GTP-fosfohydrolasy * metabolismus   genetika   MeSH
• lidé MeSH
• MAP kinasový signální systém * genetika   MeSH
• melanom * genetika   metabolismus   patologie   MeSH
• membránové proteiny * metabolismus   genetika   MeSH
• mutace * MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• protoonkogenní proteiny B-Raf * genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The RAS pathway is among the most frequently activated signaling nodes in cancer. However, the mechanisms that alter RAS activity in human pathologies are not entirely understood. The most prevalent post-translational modification within the GTPase core domain of NRAS and KRAS is ubiquitination at lysine 128 (K128), which is significantly decreased in cancer samples compared to normal tissue. Here, we found that K128 ubiquitination creates an additional binding interface for RAS GTPase-activating proteins (GAPs), NF1 and RASA1, thus increasing RAS binding to GAP proteins and promoting GAP-mediated GTP hydrolysis. Stimulation of cultured cancer cells with growth factors or cytokines transiently induces K128 ubiquitination and restricts the extent of wild-type RAS activation in a GAP-dependent manner. In KRAS mutant cells, K128 ubiquitination limits tumor growth by restricting RAL/ TBK1 signaling and negatively regulating the autocrine circuit induced by mutant KRAS. Reduction of K128 ubiquitination activates both wild-type and mutant RAS signaling and elicits a senescence-associated secretory phenotype, promoting RAS-driven pancreatic tumorigenesis.

• MeSH
• GTP-fosfohydrolasy metabolismus   genetika   MeSH
• lidé MeSH
• lysin metabolismus   MeSH
• membránové proteiny metabolismus   genetika   MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• neurofibromin 1 MeSH
• protein aktivující GTPasu p120 metabolismus   genetika   MeSH
• protein-serin-threoninkinasy metabolismus   genetika   MeSH
• protoonkogenní proteiny p21(ras) * metabolismus   genetika   MeSH
• Ras proteiny metabolismus   genetika   MeSH
• signální transdukce MeSH
• ubikvitinace * MeSH
• vazba proteinů * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Targeting Anaplastic lymphoma kinase (ALK) is a promising therapeutic strategy for aberrant ALK-expressing malignancies including neuroblastoma, but resistance to ALK tyrosine kinase inhibitors (ALK TKI) is a distinct possibility necessitating drug combination therapeutic approaches. Using high-throughput, genome-wide CRISPR-Cas9 knockout screens, we identify miR-1304-5p loss as a desensitizer to ALK TKIs in aberrant ALK-expressing neuroblastoma; inhibition of miR-1304-5p decreases, while mimics of this miRNA increase the sensitivity of neuroblastoma cells to ALK TKIs. We show that miR-1304-5p targets NRAS, decreasing cell viability via induction of apoptosis. It follows that the farnesyltransferase inhibitor (FTI) lonafarnib in addition to ALK TKIs act synergistically in neuroblastoma, inducing apoptosis in vitro. In particular, on combined treatment of neuroblastoma patient derived xenografts with an FTI and an ALK TKI complete regression of tumour growth is observed although tumours rapidly regrow on cessation of therapy. Overall, our data suggests that combined use of ALK TKIs and FTIs, constitutes a therapeutic approach to treat high risk neuroblastoma although prolonged therapy is likely required to prevent relapse.

• MeSH
• anaplastická lymfomová kináza * genetika   metabolismus   antagonisté a inhibitory   MeSH
• apoptóza účinky léků   genetika   MeSH
• chemorezistence genetika   účinky léků   MeSH
• dibenzocyklohepteny * MeSH
• farnesyltranstransferasa * antagonisté a inhibitory   metabolismus   MeSH
• GTP-fosfohydrolasy * genetika   metabolismus   MeSH
• inhibitory proteinkinas * farmakologie   terapeutické užití   MeSH
• lidé MeSH
• membránové proteiny metabolismus   genetika   MeSH
• mikro RNA * genetika   metabolismus   MeSH
• mutace MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• neuroblastom * farmakoterapie   genetika   patologie   metabolismus   MeSH
• piperidiny * farmakologie   terapeutické užití   MeSH
• pyridiny * farmakologie   terapeutické užití   MeSH
• regulace genové exprese u nádorů účinky léků   MeSH
• synergismus léků MeSH
• xenogenní modely - testy antitumorózní aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Altered cell metabolism is a hallmark of cancer, and targeting specific metabolic nodes is considered an attractive strategy for cancer therapy. In this study, we evaluate the effects of metabolic stressors on the deregulated ERK pathway in melanoma cells bearing activating mutations of the NRAS or BRAF oncogenes. We report that metabolic stressors promote the dimerization of KSR proteins with CRAF in NRAS-mutant cells, and with oncogenic BRAF in BRAFV600E-mutant cells, thereby enhancing ERK pathway activation. Despite this similarity, the two genomic subtypes react differently when a higher level of metabolic stress is induced. In NRAS-mutant cells, the ERK pathway is even more stimulated, while it is strongly downregulated in BRAFV600E-mutant cells. We demonstrate that this is caused by the dissociation of mutant BRAF from KSR and is mediated by activated AMPK. Both types of ERK regulation nevertheless lead to cell cycle arrest. Besides studying the effects of the metabolic stressors on ERK pathway activity, we also present data suggesting that for efficient therapies of both genomic melanoma subtypes, specific metabolic targeting is necessary.

• MeSH
• aktivace enzymů MeSH
• extracelulárním signálem regulované MAP kinasy metabolismus   MeSH
• fyziologický stres * MeSH
• glukosa metabolismus   MeSH
• glykolýza MeSH
• GTP-fosfohydrolasy genetika   metabolismus   MeSH
• kontrolní body buněčného cyklu genetika   MeSH
• lidé MeSH
• melanom genetika   metabolismus   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• multimerizace proteinu * MeSH
• mutace MeSH
• nádorové buněčné linie MeSH
• proteinkinasy chemie   genetika   metabolismus   MeSH
• proteiny 14-3-3 chemie   metabolismus   MeSH
• raf kinasy chemie   genetika   metabolismus   MeSH
• rekombinantní fúzní proteiny MeSH
• spotřeba kyslíku MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

During translation termination in bacteria, the release factors RF1 and RF2 are recycled from the ribosome by RF3. While high-resolution structures of the individual termination factors on the ribosome exist, direct structural insight into how RF3 mediates dissociation of the decoding RFs has been lacking. Here we have used the Apidaecin 137 peptide to trap RF1 together with RF3 on the ribosome and visualize an ensemble of termination intermediates using cryo-electron microscopy. Binding of RF3 to the ribosome induces small subunit (SSU) rotation and swivelling of the head, yielding intermediate states with shifted P-site tRNAs and RF1 conformations. RF3 does not directly eject RF1 from the ribosome, but rather induces full rotation of the SSU that indirectly dislodges RF1 from its binding site. SSU rotation is coupled to the accommodation of the GTPase domain of RF3 on the large subunit (LSU), thereby promoting GTP hydrolysis and dissociation of RF3 from the ribosome.

• MeSH
• elektronová kryomikroskopie MeSH
• Escherichia coli genetika   metabolismus   MeSH
• GTP-fosfohydrolasy metabolismus   MeSH
• kationické antimikrobiální peptidy farmakologie   MeSH
• konformace proteinů MeSH
• peptidy - faktory ukončení metabolismus   MeSH
• proteiny z Escherichia coli metabolismus   MeSH
• proteosyntéza účinky léků   MeSH
• ribozomální proteiny metabolismus   MeSH
• ribozomy metabolismus   MeSH
• RNA transferová metabolismus   MeSH
• simulace molekulového dockingu MeSH
• terminace translace peptidového řetězce MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• velké podjednotky ribozomu bakteriální metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

PURPOSE: To determine the molecular genetic cause in previously unreported probands with optic atrophy from the United Kingdom, Czech Republic and Canada. METHODS: OPA1 coding regions and flanking intronic sequences were screened by direct sequencing in 82 probands referred with a diagnosis of bilateral optic atrophy. Detected rare variants were assessed for pathogenicity by in silico analysis. Segregation of the identified variants was performed in available first degree relatives. RESULTS: A total of 29 heterozygous mutations evaluated as pathogenic were identified in 42 probands, of these seven were novel. In two probands, only variants of unknown significance were found. 76% of pathogenic mutations observed in 30 (71%) of 42 probands were evaluated to lead to unstable transcripts resulting in haploinsufficiency. Three probands with the following disease-causing mutations c.1230+1G>A, c.1367G>A and c.2965dup were documented to suffer from hearing loss and/or neurological impairment. CONCLUSIONS: OPA1 gene screening in patients with bilateral optic atrophy is an important part of clinical evaluation as it may establish correct clinical diagnosis. Our study expands the spectrum of OPA1 mutations causing dominant optic atrophy and supports the fact that haploinsufficiency is the most common disease mechanism.

• MeSH
• autozomálně dominantně dědičná optická atrofie genetika   metabolismus   MeSH
• DNA genetika   MeSH
• fenotyp MeSH
• genetické techniky MeSH
• GTP-fosfohydrolasy genetika   metabolismus   MeSH
• heterozygot MeSH
• lidé MeSH
• mutace * MeSH
• mutační analýza DNA MeSH
• rodokmen MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Kanada MeSH
• Spojené království MeSH

Cancer development is a dynamic process during which the successive accumulation of mutations results in cells with increasingly malignant characteristics. Here, we show the clonal evolution pattern in myelodysplastic syndrome (MDS) patients receiving supportive care, with or without lenalidomide (follow-up 2.5-11 years). Whole-exome and targeted deep sequencing at multiple time points during the disease course reveals that both linear and branched evolutionary patterns occur with and without disease-modifying treatment. The application of disease-modifying therapy may create an evolutionary bottleneck after which more complex MDS, but also unrelated clones of haematopoietic cells, may emerge. In addition, subclones that acquired an additional mutation associated with treatment resistance (TP53) or disease progression (NRAS, KRAS) may be detected months before clinical changes become apparent. Monitoring the genetic landscape during the disease may help to guide treatment decisions.

• MeSH
• buňky kostní dřeně účinky léků   metabolismus   patologie   MeSH
• chemorezistence genetika   MeSH
• GTP-fosfohydrolasy genetika   metabolismus   MeSH
• inhibitory angiogeneze terapeutické užití   MeSH
• klonální evoluce účinky léků   MeSH
• lenalidomid MeSH
• lidé středního věku MeSH
• lidé MeSH
• management nemoci MeSH
• membránové proteiny genetika   metabolismus   MeSH
• monitorování fyziologických funkcí MeSH
• mutace MeSH
• myelodysplastické syndromy farmakoterapie   genetika   metabolismus   patologie   MeSH
• nádorové biomarkery genetika   metabolismus   MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• následné studie MeSH
• progrese nemoci MeSH
• protoonkogenní proteiny p21(ras) genetika   metabolismus   MeSH
• regulace genové exprese u nádorů * MeSH
• sekvenování exomu MeSH
• senioři MeSH
• thalidomid analogy a deriváty   terapeutické užití   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Mitochondrial DNA (mtDNA) is compacted in ribonucleoprotein complexes called nucleoids, which can divide or move within the mitochondrial network. Mitochondrial nucleoids are able to aggregate into clusters upon reaction with intercalators such as the mtDNA depletion agent Ethidium Bromide (EB) or anticancer drug Doxorobicin (DXR). However, the exact mechanism of nucleoid clusters formation remains unknown. Resolving these processes may help to elucidate the mechanisms of DXR-induced cardiotoxicity. Therefore, we addressed the role of two key nucleoid proteins; mitochondrial transcription factor A (TFAM) and mitochondrial single-stranded binding protein (mtSSB); in the formation of mitochondrial nucleoid clusters during the action of intercalators. We found that both intercalators cause numerous aberrations due to perturbing their native status. By blocking mtDNA replication, both agents also prevented mtDNA association with TFAM, consequently causing nucleoid aggregation into large nucleoid clusters enriched with TFAM, co-existing with the normal nucleoid population. In the later stages of intercalation (>48h), TFAM levels were reduced to 25%. In contrast, mtSSB was released from mtDNA and freely distributed within the mitochondrial network. Nucleoid clusters mostly contained nucleoids with newly replicated mtDNA, however the nucleoid population which was not in replication mode remained outside the clusters. Moreover, the nucleoid clusters were enriched with p53, an anti-oncogenic gatekeeper. We suggest that mitochondrial nucleoid clustering is a mechanism for protecting nucleoids with newly replicated DNA against intercalators mediating genotoxic stress. These results provide new insight into the common mitochondrial response to mtDNA stress and can be implied also on DXR-induced mitochondrial cytotoxicity.

• MeSH
• buňky Hep G2 MeSH
• DNA vazebné proteiny metabolismus   MeSH
• doxorubicin MeSH
• ethidium MeSH
• GTP-fosfohydrolasy metabolismus   MeSH
• jaterní mitochondrie metabolismus   MeSH
• lidé MeSH
• mitochondriální DNA metabolismus   MeSH
• mitochondriální proteiny metabolismus   MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• poškození DNA MeSH
• proteiny asociované s mikrotubuly metabolismus   MeSH
• transkripční faktory metabolismus   MeSH
• transportní proteiny mitochondriální membrány metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Mitochondrial protein homeostasis is crucial for cellular function and integrity and is therefore maintained by several classes of proteins possessing chaperone and/or proteolytic activities. In the present study, we focused on characterization of LACE1 (lactation elevated 1) function in mitochondrial protein homeostasis. LACE1 is the human homologue of yeast mitochondrial Afg1 (ATPase family gene 1) ATPase, a member of the SEC18-NSF, PAS1, CDC48-VCP, TBP family. Yeast Afg1 was shown to mediate degradation of mitochondrially encoded complex IV subunits, and, on the basis of its similarity to CDC48 (p97/VCP), it was suggested to facilitate extraction of polytopic membrane proteins. We show that LACE1, which is a mitochondrial integral membrane protein, exists as part of three complexes of approximately 140, 400 and 500 kDa and is essential for maintenance of fused mitochondrial reticulum and lamellar cristae morphology. We demonstrate that LACE1 mediates degradation of nuclear-encoded complex IV subunits COX4 (cytochrome c oxidase 4), COX5A and COX6A, and is required for normal activity of complexes III and IV of the respiratory chain. Using affinity purification of LACE1-FLAG expressed in a LACE1-knockdown background, we show that the protein interacts physically with COX4 and COX5A subunits of complex IV and with mitochondrial inner-membrane protease YME1L. Finally, we demonstrate by ectopic expression of both K142A Walker A and E214Q Walker B mutants, that an intact ATPase domain is essential for LACE1-mediated degradation of nuclear-encoded complex IV subunits. Thus the present study establishes LACE1 as a novel factor with a crucial role in mitochondrial protein homeostasis.

• MeSH
• adenosintrifosfatasy genetika   metabolismus   MeSH
• cyklooxygenasy genetika   metabolismus   MeSH
• GTP-fosfohydrolasy genetika   metabolismus   MeSH
• HEK293 buňky MeSH
• konformace proteinů MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• mitochondriální proteiny genetika   metabolismus   MeSH
• mitochondrie ultrastruktura   MeSH
• mutace MeSH
• podjednotky proteinů MeSH
• regulace genové exprese enzymů fyziologie   MeSH
• RNA interference MeSH
• spotřeba kyslíku MeSH
• transport elektronů fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Mitochondrial ATPases associated with diverse cellular activities (AAA) proteases are involved in the quality control and processing of inner-membrane proteins. Here we investigate the cellular activities of YME1L, the human orthologue of the Yme1 subunit of the yeast i-AAA complex, using stable short hairpin RNA knockdown and expression experiments. Human YME1L is shown to be an integral membrane protein that exposes its carboxy-terminus to the intermembrane space and exists in several complexes of 600-1100 kDa. The stable knockdown of YME1L in human embryonic kidney 293 cells led to impaired cell proliferation and apoptotic resistance, altered cristae morphology, diminished rotenone-sensitive respiration, and increased susceptibility to mitochondrial membrane protein carbonylation. Depletion of YME1L led to excessive accumulation of nonassembled respiratory chain subunits (Ndufb6, ND1, and Cox4) in the inner membrane. This was due to a lack of YME1L proteolytic activity, since the excessive accumulation of subunits was reversed by overexpression of wild-type YME1L but not a proteolytically inactive YME1L variant. Similarly, the expression of wild-type YME1L restored the lamellar cristae morphology of YME1L-deficient mitochondria. Our results demonstrate the importance of mitochondrial inner-membrane proteostasis to both mitochondrial and cellular function and integrity and reveal a novel role for YME1L in the proteolytic regulation of respiratory chain biogenesis.

• MeSH
• apoptóza MeSH
• genový knockdown MeSH
• GTP-fosfohydrolasy metabolismus   MeSH
• lidé MeSH
• metaloendopeptidasy metabolismus   MeSH
• mitochondriální membrány metabolismus   MeSH
• mitochondrie metabolismus   MeSH
• NADH, NADPH oxidoreduktasy metabolismus   MeSH
• proliferace buněk MeSH
• proteasy závislé na ATP metabolismus   MeSH
• proteasy metabolismus   MeSH
• protein - isoformy metabolismus   MeSH
• respirační komplex IV metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny metabolismus   MeSH
• Saccharomyces cerevisiae cytologie   metabolismus   MeSH
• transport elektronů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH