Mammalian Complex Research Articles

Smarce1 mutants have a defective endocardium and an increased expression of cardiac transcription factors in zebrafish

SWI/SNF or BAF chromatin-remodeling complexes are polymorphic assemblies of homologous subunit families that remodel nucleosomes and facilitate tissue-specific gene regulation during development. BAF57/SMARCE1 is a BAF complex subunit encoded in animals by a single gene and is a component of all mammalian BAF complexes. In vivo, the loss of SMARCE1 would lead to the formation of deficient combinations of the complex which might present limited remodeling activities. To address the specific contribution of SMARCE1 to the function of the BAF complex, we generated CRISPR/Cas9 mutations of smarce1 in zebrafish. Smarce1 mutants showed visible defects at 72 hpf, including smaller eyes, abnormal body curvature and heart abnormalities. Gene expression analysis revealed that the mutant embryos displayed defects in endocardial development since early stages, which led to the formation of a misshapen heart tube. The severe morphological and functional cardiac problems observed at 4 dpf were correlated with the substantially increased expression of different cardiac transcription factors. Additionally, we showed that Smarce1 binds to cis-regulatory regions of the gata5 gene and is necessary for the recruitment of the BAF complex to these regions.

Insights into the Noncoding RNA-encoded Peptides.

Considerable evidence has indicated that most noncoding RNA (ncRNA) transcripts act directly as functional RNAs rather than as encoded peptides. However, a recent study of ribosome occupancy reported that many large intergenic ncRNAs (lincRNAs) are bound by ribosomes, raising the possibility that they are translated into proteins. These lincRNAs contain either Internal Ribosomal Entry Sites (IRES) or short Open Reading Frames (sORFs), and other translation elements, which can be translated into peptides with physiological functions. This review discusses three major types of ncRNA-encoded peptides (ncPEPs). First, microRNA(miRNA)-encoded peptides (miPEPs) are translated from their primary transcripts of miRNA genes and can promote the development of plant roots. Second, a long ncRNA(lncRNA) containing sORF encodes a 90 residues long regulatory peptide. Upon the amino acid response, the lncRNA-encoded peptide reduces the activity of mammalian Target Rapamycin complex 1 (mTORC1) and promotes muscle regeneration. Third, a circular RNA (circRNA) of the Na+/Ca2+ exchanger gene 1 (NCX1) exon 2 transcript encodes a truncated NCX1 protein exhibiting the Na+/Ca2+ exchange activity. It is also of worth noting that the majority of ncRNAs is not translated. This review summarizes the current understanding of the translatability of ncRNAs and the functions of ncPEPs in cellular processes, which may provide novel insights into the roles of ncPEPs.

PO-278 The Mechanism Of LIL combined with AZD8055 On The Glutamine Addiction Of CT26 Cells

Objective The photobiomodulation of low-intensity lasers can activate many pathways and molecules, which involved in tumor growth, invasion, metastasis, and resistance to drugs or radiation therapy, but studies of low-intensity lasers on tumor cell addiction, have not been reported. Numerous studies have shown that changes in plasma and muscle glutamine levels can occur when the body undergoes prolonged exercise (>1 hour) or overtraining. AZD8055 is a dual inhibitor of mammalian rapamycin complex (mTORC)1/mTORC2 that inhibits phosphorylation of mTORC1 (p70S6K and 4E-BP1), mTORC2 (AKT) and downstream proteins.
 Based on the experimental model of glutamine addiction in laboratory, we chose the worst conditions to cause super-proliferation of CT26 cells and simulate the drug resistance of solid tumors. The purpose is to study tumor deterioration from the perspective of tumor cell function. Under the state, the effect of low-intensity laser combined with AZD8055 on the proliferation of glutamine addiction in CT26 cells is also the development of exercise intervention tumors, and the experimental basis is proposed from the perspective of nutrient metabolism.
 Methods This experiment used a pre-experimental glutamine addiction model to culture mouse colon cancer CT26 cells after horse serum shock, and used different intensity 640±15 nm low-intensity lasers from light-emitting diode arrays (red light at 640±15 nm from Light emitting diode array, RLED), 15 min/day；different concentrations of AZD8055 (0 ~ 100μM) on different proliferative CT26 cells at different times.
 Cell proliferation was detected by MTT assay; mRNA levels of proliferation-related genes were detected by RT-PCR; protein levels were detected by western blot.
 The data were analyzed by SPSS21.0 statistical software and self-similarity index analysis. Among them, the statistical significance level was set at 0.05, P<0.05 was different; P<0.01 was significant difference. In the self-similarity index analysis method, l>0.8 is a significant difference.
 Results 1.CT26 cells were incubated at Gln7.94 mM until the 8th day, and AZD8055 was added at different concentrations. Compared with no inhibitor , and at 6 h, the cells were significantly increased when the concentration of AZD8055 was 0.001 μM, 1 μM, 10 μM and 100 μM. (P<0.01); at 12h, the cells were significantly inhibition when the of AZD8055>0.5μM (P<0.01).
 2.From the growth inhibition rate analysis, at 48 h and 72 h, the inhibition rate exceeded 50%,when the concentration of AZD8055 was 100 μM (61.01% and 87.46%), when< 0.1 μM, the cells were proliferation occurred at 48 h and 72 h, and it is drug resistance.
 3.When AZD8055 combined with low-intensity laser treatment of CT26 cells, CT26 cells had different degrees of proliferative effects at different time points: 12h, 24h, 48h and 72h. Especially at 48h, the light intensity of LIL2 to LIL8 had a significant proliferative effect on CT26 cells (l≥0.8).
 4.Compared with the control group (0 hours without inhibitor), the CT26 cells were treatment with AZD8055 1μM , the mRNA level of the gene GLUT1 was significantly down-regulated in all time periods (P<0.01). When the LIL(2.17 mW/cm2) combined AZD8055 (1μM) significantly promoted the proliferation of CT26 cells at 24h and 48h. It is related to up-regulated of protein expression in all time points: at 6h and 12h, the pMEK protein and the pMEK/ MEK were significantly up-regulated(P<0.01). At 24h, the expression of GLUT1 protein was up-regulated(P<0.01), MEK protein, pERK protein and ERK/ pERK were significantly up-regulated (P<0.01). At 48h, the GLUT1 protein, MEK protein , pERK protein and pERK/ERK were up-regulated (P<0.01).
 Conclusions 1.The minimum inhibitory concentration of AZD8055 on super-proliferative CT26 cells was 0.5 μM, and the super-proliferative state showed more obvious drug resistance.
 2.When low-intensity lasers combined with AZD8055 treated CT26 super-proliferating cells, CT26 cells are not sensitive to AZD8055, while low-intensity lasers promote CT26 cells proliferation by up-regulating MEK/ERK signaling pathways.

Release of Ubiquitinated and Non-ubiquitinated Nascent Chains from Stalled Mammalian Ribosomal Complexes by ANKZF1 and Ptrh1

The ribosome-associated quality control (RQC) pathway degrades nascent chains (NCs) arising from interrupted translation. First, recycling factors split stalled ribosomes, yielding NC-tRNA/60S ribosome-nascent chain complexes (60S RNCs). 60S RNCs associate with NEMF, which recruits the E3 ubiquitin ligase Listerin that ubiquitinates NCs. The mechanism of subsequent ribosomal release of Ub-NCs remains obscure. We found that, in non-ubiquitinated 60S RNCs and 80S RNCs formed on non-stop mRNAs, tRNA is not firmly fixed in the P site, which allows peptidyl-tRNA hydrolase Ptrh1 to cleave NC-tRNA, suggesting the existence of a pathway involving release of non-ubiquitinated NCs. Association with NEMF and Listerin and ubiquitination of NCs results in accommodation of NC-tRNA, rendering 60S RNCs resistant to Ptrh1 but susceptible to ANKZF1, which induces specific cleavage in the tRNA acceptor arm, releasing proteasome-degradable Ub-NCs linked to four 3'-terminal tRNA nucleotides. We also found that TCF25, a poorly characterized RQC component, ensures preferential formation of the K48-ubiquitin linkage.

Deciphering mediator's function and structure in mammalian cells

Introduction/Objectives Mediator is a multi-subunit complex organized into four modules (head, middle, tail and kinase module). It is involved in several steps of PolII-dependent transcription and enhancer–promoter (E–P) interactions. Mutations in different subunits (SU) are associated with cancer and developmental diseases. Mediator's function and structure have been mainly studied in yeast. Earlier studies suggest significant differences with the mammalian complex in terms of composition and structure. Additionally, the chromatin architecture between both species is different, particularly E–P interactions. We aimed to comprehensively characterize the mammalian complex. Materials/Patients and methods We screened for cell essentiality of Mediator subunits, in a murine B-lymphoma cell line, CH12, in embryonic stem cells and in primary CD4T cells, using CRISPR-Cas9 technology. We generated knockout clones (KO) whenever possible in CH12 cells, and a degron-based conditional KO of the essential Mediator's backbone, Med14. We analyzed the impact on gene expression (RNAseq), on PolII and Mediator recruitment at promoters and enhancers (ChIPseq), on chromatin accessibility (ATACseq), on histone modifications (MNase ChIPseq), on chromatin architecture (in situ HiC) and on structure (cryo-EM). Results Depletion of non-essential SUs induces transcriptional deregulation of only a subset of genes, whereas depleting the essential Med14 induces global decrease in transcription associated with a decrease in PolII recruitment. Interestingly, the ablation of the whole tail module is viable. With this tailless model and the Med14-degron we do not observe an impact on chromatin architecture. Preliminary cryo-EM results show a conserved location of common SUs between yeast and mammalian cells. We are able to locate mammalian specific SUs and describe the interactions between the different SUs in the mammalian complex. Conclusions Our study provides new insights into mammalian Mediator structure and a comprehensive view on how Mediator and its tail module are involved in transcription and chromatin architecture. This data is essential for a better understanding of transcriptional regulation and Mediator related diseases.

The mechanism of mammalian respiratory complex I

The mechanism of mammalian respiratory complex I

PTE, a novel module to target Polycomb Repressive Complex 1 to the human cyclin D2 (CCND2) oncogene

Polycomb group proteins are essential epigenetic repressors. They form multiple protein complexes of which two kinds, PRC1 and PRC2, are indispensable for repression. Although much is known about their biochemical properties, how mammalian PRC1 and PRC2 are targeted to specific genes is poorly understood. Here, we establish the cyclin D2 (CCND2) oncogene as a simple model to address this question. We provide the evidence that the targeting of PRC1 to CCND2 involves a dedicated PRC1-targeting element (PTE). The PTE appears to act in concert with an adjacent cytosine-phosphate-guanine (CpG) island to arrange for the robust binding of PRC1 and PRC2 to repressed CCND2 Our findings pave the way to identify sequence-specific DNA-binding proteins implicated in the targeting of mammalian PRC1 complexes and provide novel link between polycomb repression and cancer.

ATP synthase purification and subunit composition analysis in the models of mammalian Complex V deficiencies

ATP synthase purification and subunit composition analysis in the models of mammalian Complex V deficiencies

Recycling of Golgi glycosyltransferases requires direct binding to coatomer

The glycosyltransferases of the mammalian Golgi complex must recycle between the stacked cisternae of that organelle to maintain their proper steady-state localization. This trafficking is mediated by COPI-coated vesicles, but how the glycosyltransferases are incorporated into these transport vesicles is poorly understood. Here we show that the N-terminal cytoplasmic tails (N-tails) of a number of cis Golgi glycosyltransferases which share a ϕ-(K/R)-X-L-X-(K/R) sequence bind directly to the δ- and ζ-subunits of COPI. Mutations of this N-tail motif impair binding to the COPI subunits, leading to mislocalization of the transferases to lysosomes. The physiological importance of these interactions is illustrated by mucolipidosis III patients with missense mutations in the N-tail of GlcNAc-1-phosphotransferase that cause the transferase to be rapidly degraded in lysosomes. These studies establish that direct binding of the N-tails of mammalian cis Golgi glycosyltransferases with COPI subunits is essential for recycling within the Golgi.

Canonical PRC2 function is essential for mammary gland development and affects chromatin compaction in mammary organoids.

Distinct transcriptional states are maintained through organization of chromatin, resulting from the sum of numerous repressive and active histone modifications, into tightly packaged heterochromatin versus more accessible euchromatin. Polycomb repressive complex 2 (PRC2) is the main mammalian complex responsible for histone 3 lysine 27 trimethylation (H3K27me3) and is integral to chromatin organization. Using in vitro and in vivo studies, we show that deletion of Suz12, a core component of all PRC2 complexes, results in loss of H3K27me3 and H3K27 dimethylation (H3K27me2), completely blocks normal mammary gland development, and profoundly curtails progenitor activity in 3D organoid cultures. Through the application of mammary organoids to bypass the severe phenotype associated with Suz12 loss in vivo, we have explored gene expression and chromatin structure in wild-type and Suz12-deleted basal-derived organoids. Analysis of organoids led to the identification of lineage-specific changes in gene expression and chromatin structure, inferring cell type–specific PRC2-mediated gene silencing of the chromatin state. These expression changes were accompanied by cell cycle arrest but not lineage infidelity. Together, these data indicate that canonical PRC2 function is essential for development of the mammary gland through the repression of alternate transcription programs and maintenance of chromatin states.

A Cross Talk Between BRG1 and Males Absent on the First Contributes to Reactive Oxygen Species Production in a Mouse Model of Nonalcoholic Steatohepatitis.

Aims: Accumulation of reactive oxygen species (ROS) in hepatocytes in response to excessive nutrients and the ensuing liver damages caused by ROS constitute a key pathophysiological event in nonalcoholic steatohepatitis (NASH). In the present study, we investigated the epigenetic mechanism underlying ROS production in NASH pathogenesis. Results: NASH was induced by feeding the mice with a methionine-and-choline-deficient (MCD) diet for 4 weeks. Compared with the control mice (wild type [WT]), mice with hepatocyte-specific deletion of Brg1 (HepcKO), a core component of the mammalian chromatin remodeling complex, developed a less severe form of NASH when fed on the MCD diet. Importantly, ROS levels were attenuated in HepcKO mice as opposed to WT mice. Brahma-related gene 1 (Brg1) deficiency downregulated the transcription of NADPH oxidases (NOX1, NOX2, and NOX4) both in vivo and in vitro. Mechanistically, Brg1 deletion rendered a more repressive chromatin structure surrounding the NOX promoters as characterized by reduced levels of acetylated histones. In addition, Brg1 interacted with the histone H4K16 acetyltransferase males absent on the first (MOF) to activate NOX transcription. MOF knockdown by small interfering RNA or pharmaceutical inhibition by MG149 suppressed NOX transcription and ameliorated ROS levels. Innovation: Our data highlight a novel epigenetic mechanism through which Brg1 and MOF cooperate to regulate ROS production in hepatocytes in response to pro-NASH stimuli. Conclusion: A cross talk between Brg1 and MOF epigenetically activates NOX transcription and elevates ROS synthesis contributing to NASH pathogenesis.

Assembly of mammalian oxidative phosphorylation complexes I-V and supercomplexes.

The assembly of the five oxidative phosphorylation system (OXPHOS) complexes in the inner mitochondrial membrane is an intricate process. The human enzymes comprise core proteins, performing the catalytic activities, and a large number of ‘supernumerary’ subunits that play essential roles in assembly, regulation and stability. The correct addition of prosthetic groups as well as chaperoning and incorporation of the structural components require a large number of factors, many of which have been found mutated in cases of mitochondrial disease. Nowadays, the mechanisms of assembly for each of the individual complexes are almost completely understood and the knowledge about the assembly factors involved is constantly increasing. On the other hand, it is now well established that complexes I, III and IV interact with each other, forming the so-called respiratory supercomplexes or ‘respirasomes’, although the pathways that lead to their formation are still not completely clear. This review is a summary of our current knowledge concerning the assembly of complexes I–V and of the supercomplexes.

Mitochondrial complex I in the post-ischemic heart: reperfusion-mediated oxidative injury and protein cysteine sulfonation

A serious consequence of ischemia-reperfusion injury (I/R) is oxidative damage leading to mitochondrial dysfunction. Such I/R-induced mitochondrial dysfunction is observed as impaired state 3 respiration and overproduction of O2−. The cascading ROS can propagate cysteine oxidation on mitochondrial complex I and add insult to injury. Herein we employed LC-MS/MS to identify protein sulfonation of complex I in mitochondria from the infarct region of rat hearts subjected to 30-min of coronary ligation and 24-h of reperfusion in vivo as well as the mitochondria of sham controls. Mitochondrial preparations from the I/R regions had enhanced sulfonation levels on the cysteine ligands of iron‑sulfur clusters, including N3 (C425), N1b (C92), N4 (C226), N2 (C158/C188), and N1a (C134/C139). The 4Fe-4S centers of N3, N1b, N4, and N2 are key redox-active components of complex I, thus sulfonation of metal-binding sites impaired the main electron transfer pathway. The binuclear N1a has a very low redox potential and an antioxidative function. Increased C134/C139 sulfonation by I/R impaired the N1a cluster, potentially contributing to overall O2− generation by the FMN moiety of complex I. MS analysis also revealed I/R-mediated increased sulfonation at the core subunits of 51 kDa (C125, C187, C206, C238, C255, C286), 75 kDa (C367, C554, C564, C727), 49 kDa (C146, C326, C347), and PSST (C188). These results were consistent with the consensus indicating that 51 kDa and 75 kDa are two of major subunits hosting regulatory thiols, and their enhanced sulfonation by I/R predisposed the myocardium to further oxidant stress with impaired ubiquinone reduction. MS analysis further showed I/R-mediated enhanced sulfonation at the supernumerary subunits of 42 kDa (C67, C112, C183, C253), 15 kDa (C43), and 13 kDa (C79). The 42 kDa protein is metazoan-specific, which was reported to stabilize mammalian complex I. C43 of the 15 kDa subunit forms an intramolecular disulfide bond with C56, which was reported to stabilize complex I structure. C79 of the 13 kDa subunit is involved in Zn2+-binding, which was reported functionally important for complex I assembly. C79 sulfonation by I/R was found to impair Zn2+-binding. No significant enhancement of protein sulfonation was observed in mitochondrial complex I from the rat heart subjected to 30-min ischemia alone in vivo despite a decreased state 3 respiration, suggesting that the physiologic conditions of hyperoxygenation during reperfusion mediated an increase in complex I sulfonation and oxidative injury. In conclusion, sulfonation of specific cysteines of complex I mediates I/R-induced mitochondrial dysfunction via impaired ETC activity, increasing •O2− production, and mediating redox dysfunction of complex I.

Abstract 1472: The role of the BAF complex in Wnt signaling-mediated transcriptional regulation in colorectal cancer

Abstract Recent genome- and exome-wide sequencing studies have revealed a close association between the epigenome and the pathogenesis of cancer. Not only were chromatin regulators found to be commonly mutated in a wide range of cancers, but a class of these regulators, the ATP-dependent chromatin remodelers, especially subunits of the mammalian BAF complex, were among the most frequently mutated group of genes across cancer types, mutated in over 20% of cancers. Among these subunits, loss of function mutations in ARID1A (AT-rich interactive domain-containing protein 1A) are most frequent across cancer types including 10% of colorectal cancer (CRC). Very interestingly, a recent publication described the pivotal role of the loss of ARID1A in driving CRC wherein its inactivation alone led to the formation of invasive adenocarcinomas in mice. However, surprisingly, in contrast to the expected tumor suppressive role of ARID1A in CRC, we observe that the knockout (KO) of ARID1A in CRC cell lines leads to impaired proliferation. Moreover, subcutaneous xenografts in SCID/SHO mice using ARID1A KO CRC cells did not form more aggressive tumors than their wild type counterparts. One of the most commonly occurring mutations in CRC is in the APC gene, which leads to hyperactive Wnt signaling. Thus CRC progression is typically highly dependent on this pathway. Notably, it is reported that loss of ARID1A in the context of APC mutations results in diminished tumor formation in mice and increased differentiation. This led us to hypothesize that ARID1A is required for Wnt signaling-mediated transcriptional (de)regulation in CRC. To uncover this further, we utilized several publically available ChIP-seq, RNA-seq and ATAC-seq datasets as well as our own ChIP-seq data for ARID1A in the HCT116 cell line. We observe a substantial co-localization of the BAF complex with TCF7L2, a downstream effector of the Wnt signaling pathway, suggesting cooperation between these factors. Further, these sites are also co-occupied by AP1 transcription factors. A crosstalk between the TCF7L2 and AP1 factors has been reported in intestinal tumors. From data available in the ARID1A KO system, we observe a downregulation of potential target genes which are co-occupied at neighboring sites by these factors. Therefore, we suggest that ARID1A plays an important role in the regulation of colorectal cancer relevant genes that are targets of TCF7L2/AP1, thus facilitating a pathway that is most commonly hijacked in colorectal cancer. Citation Format: Madhobi Sen, Feda H. Hamdan, Xin Wang, Jacobe Rapp, Steven A. Johnsen. The role of the BAF complex in Wnt signaling-mediated transcriptional regulation in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1472.

Cultural and morphological properties of atypical mycobacteria isolated from pigs on the territory of the Novosibirsk region

When examining biomaterial from tuberculin-reacting pigs, we have isolated 58 cultures of acid-fast mycobacteria, or 7,5 percent of the number of samplesstudied. The rate of cultures isolation from hen biomaterialamounted to 12.5 percent, from synanthropic birds 7.5 percent, from environmental samples 9.4 percent. Resulting from cultural, biochemical and morphological studies, 6 species of atypical mycobacteria were found to persist in the organism of pigs, reacting to avian and mammalian PPD complexes, and in the environment of tuberculosis-free pig-producing farms in Novosibirsk Region. These mycobacteria species belong to 2–4 groups according to the Runyon’s classification, and include M. xenopi, M. avium-intracellulare, M. fortuitum, M. smegmatis, M. phlei, and M. scrofulaceum. Major field isolates from both pig biomaterial and the environment are represented by M. avium-intracellulare complex that indicates their wide distribution. From the samples of various environmental objects, being main sources of mycobacterioses in pigs, were isolated and identified 28 cultures of different species of atypical mycobacteria with M. avium-intracellulare complex prevailed.&nbsp

The multi-subunit GID/CTLH E3 ubiquitin ligase promotes cell proliferation and targets the transcription factor Hbp1 for degradation.

In yeast, the glucose-induced degradation-deficient (GID) E3 ligase selectively degrades superfluous gluconeogenic enzymes. Here, we identified all subunits of the mammalian GID/CTLH complex and provide a comprehensive map of its hierarchical organization and step-wise assembly. Biochemical reconstitution demonstrates that the mammalian complex possesses inherent E3 ubiquitin ligase activity, using Ube2H as its cognate E2. Deletions of multiple GID subunits compromise cell proliferation, and this defect is accompanied by deregulation of critical cell cycle markers such as the retinoblastoma (Rb) tumor suppressor, phospho-Histone H3 and Cyclin A. We identify the negative regulator of pro-proliferative genes Hbp1 as a bonafide GID/CTLH proteolytic substrate. Indeed, Hbp1 accumulates in cells lacking GID/CTLH activity, and Hbp1 physically interacts and is ubiquitinated in vitro by reconstituted GID/CTLH complexes. Our biochemical and cellular analysis thus demonstrates that the GID/CTLH complex prevents cell cycle exit in G1, at least in part by degrading Hbp1.

Cryo-EM structures of complex I from mouse heart mitochondria in two biochemically defined states.

Complex I (NADH:ubiquinone oxidoreductase) uses the reducing potential of NADH to drive protons across the energy-transducing inner membrane and power oxidative phosphorylation in mammalian mitochondria. Recently, cryoEM analyses have produced close-to-complete models of all 45 subunits in the bovine, ovine and porcine complexes, and identifed two states relevant to complex I in ischemia-reperfusion injury. Here, we describe the 3.3-Å structure of complex I from mouse heart mitochondria, a biomedically-relevant model system, in the ‘active’ state. We reveal a nucleotide bound in subunit NDUFA10, a nucleoside-kinase homolog, and define mechanistically-critical elements in the mammalian enzyme. By comparisons with a 3.9-Å structure of the ‘deactive’ state and with known bacterial structures we identify differences in helical geometry in the membrane domain that occur upon activation, or that alter the positions of catalytically-important charged residues. Our results demonstrate the capability of cryoEM analyses to challenge and develop mechanistic models for mammalian complex I.

In silico and in vivo investigation of ferrocene-incorporated acyl ureas and homoleptic cadmium carboxylate derivatives for anticonvulsant, anxiolytic, and sedative potential.

In this study different derivatives of ferrocene-incorporated acyl ureas and homoleptic cadmium carboxylates were investigated for potential anticonvulsant, anxiolytic and sedative properties, using in-silico and in-vivo techniques. The molecular docking studies reveled that ferrocene compounds derivative 1-(4-bromobenzoyl)-3-(4-ferrocenylphenyl) urea (PB1) and cadmium compounds derivative bis (diphenylacetato) cadmium (II) (DPAA) exhibit binding affinities against various neurotherapeutic molecular targets involved in epilepsy, anxiety, and sedation. Both PB1 and DPAA showed high binding affinities against protein targets like mammalian shaker voltage dependent potassium channel beta subunit complex, calcium release-activated calcium channel, sodium channel 2A inactivation gate, human sodium/hydrogen exchanger regulatory factor, and gamma amino butyric acid A receptor associated protein. PB1 (2-10 mg/kg) and DPAA (1-5 mg/kg) delayed onset time of pentylenetetrazole-induced myoclonic jerks and tonic-clonic seizures in mice while decreased duration of tonic-clonic seizures, determining the anticonvulsant effect of these compounds. PB1 and DPAA (0.5-1 mg/kg) exhibited anxiolytic effect by increasing time spent and number of animals entries into open arms, while decreasing time spent in dark compartment. Furthermore, PB1 (0.5-1 mg/kg) and DPAA (0.1-1 mg/kg) reduced onset time of sleep and increased duration time of sleep in mice, showing sedative effect. Taken together, our results indicate that aforementioned derivatives of ferrocene and cadmium are potent neurotherapeutic agents possessing anticonvulsant, anxiolytic and sedative properties.

Degradation of a Novel DNA Damage Response Protein, Tankyrase 1 Binding Protein 1, following Adenovirus Infection

ABSTRACTInfection by most DNA viruses activates a cellular DNA damage response (DDR), which may be to the detriment or advantage of the virus. In the case of adenoviruses, they neutralize antiviral effects of DDR activation by targeting a number of proteins for rapid proteasome-mediated degradation. We have now identified a novel DDR protein, tankyrase 1 binding protein 1 (TNKS1BP1) (also known as Tab182), which is degraded during infection by adenovirus serotype 5 and adenovirus serotype 12. In both cases, degradation requires the action of the early region 1B55K (E1B55K) and early region 4 open reading frame 6 (E4orf6) viral proteins and is mediated through the proteasome by the action of cullin-based cellular E3 ligases. The degradation of Tab182 appears to be serotype specific, as the protein remains relatively stable following infection with adenovirus serotypes 4, 7, 9, and 11. We have gone on to confirm that Tab182 is an integral component of the CNOT complex, which has transcriptional regulatory, deadenylation, and E3 ligase activities. The levels of at least 2 other members of the complex (CNOT3 and CNOT7) are also reduced during adenovirus infection, whereas the levels of CNOT4 and CNOT1 remain stable. The depletion of Tab182 with small interfering RNA (siRNA) enhances the expression of early region 1A proteins (E1As) to a limited extent during adenovirus infection, but the depletion of CNOT1 is particularly advantageous to the virus and results in a marked increase in the expression of adenovirus early proteins. In addition, the depletion of Tab182 and CNOT1 results in a limited increase in the viral DNA level during infection. We conclude that the cellular CNOT complex is a previously unidentified major target for adenoviruses during infection.IMPORTANCE Adenoviruses target a number of cellular proteins involved in the DNA damage response for rapid degradation. We have now shown that Tab182, which we have confirmed to be an integral component of the mammalian CNOT complex, is degraded following infection by adenovirus serotypes 5 and 12. This requires the viral E1B55K and E4orf6 proteins and is mediated by cullin-based E3 ligases and the proteasome. In addition to Tab182, the levels of other CNOT proteins are also reduced during adenovirus infection. Thus, CNOT3 and CNOT7, for example, are degraded, whereas CNOT4 and CNOT1 are not. The siRNA-mediated depletion of components of the complex enhances the expression of adenovirus early proteins and increases the concentration of viral DNA produced during infection. This study highlights a novel protein complex, CNOT, which is targeted for adenovirus-mediated protein degradation. To our knowledge, this is the first time that the CNOT complex has been identified as an adenoviral target.

Interrogation of Mammalian Protein Complex Structure, Function, and Membership Using Genome-Scale Fitness Screens.

Protein complexes are assemblies of subunits that have co-evolved to execute one or many coordinated functions in the cellular environment. Functional annotation of mammalian protein complexes is critical to understanding biological processes, as well as disease mechanisms. Here, we used genetic co-essentiality derived from genome-scale RNAi- and CRISPR-Cas9-based fitness screens performed across hundreds of human cancer cell lines to assign measures of functional similarity. From these measures, we systematically built and characterized functional similarity networks that recapitulate known structural and functional features of well-studied protein complexes and resolve novel functional modules within complexes lacking structural resolution, such as the mammalian SWI/SNF complex. Finally, by integrating functional networks with large protein-protein interaction networks, we discovered novel protein complexes involving recently evolved genes of unknown function. Taken together, these findings demonstrate the utility of genetic perturbation screens alone, and in combination with large-scale biophysical data, to enhance our understanding of mammalian protein complexes in normal and disease states.