Regulation of trehalase expression inhibits apoptosis in diapause cysts of Artemia
Trehalase, which specifically hydrolyzes trehalose into glucose, plays an important role in the metabolism of trehalose. Large amounts of trehalose are stored in the diapause encysted embryos (cysts) of Artemia, which are not only vital to their extraordinary stress resistance but also provide a source of energy for development after diapause is terminated. In the present study, a mechanism for the transcriptional regulation of trehalase was described in Artemia parthenogenetica. A trehalase-associated protein (ArTAP) was identified in Artemia producing diapause cysts. ArTAP was found to be expressed only in diapause-desti...
Source: BJ Gene - September 25, 2013 Category: Biochemistry Authors: F Yang, S Chen, Z Dai, D Chen, R Duan, H Wang, S Jia, W Yang Tags: BJ Biomolecules Source Type: research
Downregulation of cyclin G2 by insulin, insulin-like growth factor I (IGF-I) and AspB10 insulin (X10): role in mitogenesis
The mechanisms whereby insulin analogues may cause enhanced mitogenicity through activation of either the insulin receptor (IR) or the IGF-I receptor (IGF-IR) are incompletely understood.
We demonstrate that in L6 myoblasts expressing only IGF-IRs as well as in the same cells overexpressing the IR, IGF-I, insulin, and AspB10 insulin (X10) downregulate the mRNA expression level of the cell cycle inhibitor cyclin G2, as measured by qRT-PCR, and induce cell growth measured by [6-3H] thymidine incorporation into DNA. Western blotting showed a marked downregulation of cyclin G2 at the protein level in both cell lines. Overexpre...
Source: BJ Gene - September 24, 2013 Category: Biochemistry Authors: A Manegold Svendsen, S Bøg Winge, M Zimmermann, A Bøg Lindvig, C Becker Warzecha, W Sajid, M C. Horne, P De Meyts Tags: BJ Signal Source Type: research
Mycobacterium smegmatis Ku binds DNA without free ends
We report here that the lysine-rich C-terminal extension of M. smegmatis Ku contacts the core protein domain as evidenced by an increase in DNA-binding affinity and a decrease in thermal stability and intrinsic tryptophan fluorescence upon its deletion. Ku deleted for this C-terminus requires free DNA ends for binding, but translocates to internal DNA sites. In contrast, full-length Ku can directly bind DNA without free ends, suggesting that this property is conferred by its C-terminus. Such binding to internal DNA sites may facilitate recruitment to sites of DNA damage. Our data also suggest that extensions beyond the sha...
Source: BJ Gene - September 24, 2013 Category: Biochemistry Authors: A K Kushwaha, A Grove Tags: BJ Gene Source Type: research
Regulation of the transcriptional activation of the androgen receptor by the UXT binding protein VHL
Loss and/or inactivation of VHL (the von Hippel Lindau tumour suppressor) cause various tumours. Using a yeast two-hybrid system, we have identified an AR co-activator, UXT, as a VHL-interacting protein. GST pull-down and co-immunoprecipitation assays show that UXT interacts with VHL. In addition, UXT recruits VHL to the nucleus. VHL associates with the DBD and hinge domains of the AR and induces AR ubiquitination. Moreover, VHL interaction with the AR activates AR transactivation upon DHT treatment. VHL knockdown inhibits AR ubiquitination and decreases transcriptional activation of the AR. Our data suggest that the VHL-U...
Source: BJ Gene - August 21, 2013 Category: Biochemistry Authors: S Chen, K Chen, Q Zhang, H Cheng, R Zhou Tags: BJ Signal Source Type: research
Histone deacetylase SIRT1 modulates and deacetylates DNA base excision repair enzyme thymine DNA glycosylase
In this study, we demonstrate that SIRT1 interacts with the residues 67-110 of human TDG (hTDG). In addition, SIRT1 enhances TDG glycosylase activity and deacetylates acetylated TDG. TDG acetylation weakens its interaction with SIRT1. Although acetylated TDG has reduced glycosylase activity toward T/G, 5-formylcytosine/G, and 5-carboxylcytosine/G, it has a stronger activity toward 5-fluorouracil/G substrate as compared to unmodified TDG. SIRT1 weakly stimulates acetylated hTDG activity toward T/G, 5-formylcytosine/G, and 5-carboxylcytosine/G as compared to control hTDG. Sirt1 knockout mouse embryonic fibroblast cells have ...
Source: BJ Gene - August 16, 2013 Category: Biochemistry Authors: A Madabushi, B Hwang, J Jin, A Lu Tags: BJ ChemBio Source Type: research
The Reduction in Sigma-Promoter Recognition Flexibility as Induced by Core is Required for Sigma to Discern the Optimal Promoter Spacing
We examined this issue using a transcriptionally active Bacillus subtilis N-terminally truncated σA (SND100-σA). Our results demonstrated that SND100-σA binds specifically to both -10 and -35 elements of the trnS spacing variants, of which the spacer lengths range from 14 to 21 bp, indicating that simultaneous and specific recognition of promoter -10 and -35 elements is insufficient for primary σ to discern the optimal promoter spacing. Moreover, shortening in length of the flexible linker between the two promoter DNA-binding domains of σA also does not enable SND100-σA to sense th...
Source: BJ Gene - July 22, 2013 Category: Biochemistry Authors: H Yeh, H Hsu, T Chen, K Chung, K Liou, B Chang Tags: BJ Gene Source Type: research
The central role of mosquito cytochrome P450 CYP6Zs in insecticide detoxification revealed by functional expression and structural modelling
In this study, we created a genetically modified yeast strain over-expressing Ae. aegypti cytochrome P450 reductase and CYP6Z8, thereby producing the first mosquito P450/CPR complex in a yeast recombinant system. Our results showed that: (1) CYP6Z8 metabolizes 3-phenoxybenzoic alcohol (PBAlc) and 3-phenoxybenzaldehyde (PBAld), common pyrethroid metabolites produced by carboxylesterases, producing 3-phenoxybenzoic acid (PBA); (2) CYP6Z8 transcription is induced by PBAlc, PBAld and PBA; (3) A. gambiae CYP6Z2 metabolizes PBAlc and PBAld in the same way; (4) PBA is the major metabolite produced in vivo and is excreted without ...
Source: BJ Gene - July 11, 2013 Category: Biochemistry Authors: A Chandor-Proust, J Bibby, M Régent-Kloeckner, J Roux, E Guittard-Crilat, R Poupardin, M Riaz, M Paine, C Dauphin-Villemant, S Reynaud, J David Tags: BJ Metabolism Source Type: research
The physical interaction of Mcm10 with Cdc45 modulates their DNA binding properties
The eukaryotic DNA replication protein Mcm10 associates with chromatin in early S-phase and is required for assembly and function of the replication fork protein machinery. Another essential component of the eukaryotic replication fork is Cdc45, which is required for both initiation and elongation of DNA replication. Here, we characterize for the first time the physical and functional interactions of human Mcm10 and Cdc45. We first demonstrated that Mcm10 and Cdc45 interact cell free extracts. We then analyzed the role of each of the Mcm10 domains N-terminal, internal and C-terminal (NTD, ID and CTD, respectively). We have...
Source: BJ Gene - June 10, 2013 Category: Biochemistry Authors: R Di Perna, V Aria, M De Falco, V Sannino, A L Okorokov, F M Pisani, M De Felice Tags: BJ Gene Source Type: research
Minimal Functional Domains of Paralogues hnRNP L and hnRNP LL Exhibit Mechanistic Differences in Exonic Splicing Repression
In this study, we use an MS2-tethering assay to delineate the minimal domains of hnRNP L and hnRNP LL which are required for repressing exon inclusion. We demonstrate that for both proteins, regions outside the RRMs – the N-terminal region, and a linker sequence between RRMs 2 and 3 – are necessary for exon repression, but are only sufficient for repression in the case of hnRNP LL. In addition, both proteins require at least one RRM for maximal repression. Notably, we demonstrate that the region encompassing RRMs 1-2 of hnRNP LL imparts a second silencing activity not observed for hnRNP L. This additional fun...
Source: BJ Gene - May 7, 2013 Category: Biochemistry Authors: G Shankarling, K W Lynch Tags: BJ Gene Source Type: research
MondoA senses adenine nucleotides: transcriptional induction of thioredoxin-interacting protein
The MondoA:Mlx transcription complex plays a pivotal role in glucose homeostasis by activating target gene expression in response to glucose-6-phosphate (G6P), the first reaction intermediate in glycolysis. Thioredoxin-interacting protein (TXNIP) is a direct and glucose-responsive target of MondoA that triggers a negative feedback loop by restricting glucose uptake when G6P levels increase. We show here that TXNIP expression is also activated by 5-aminoimidazole-4-carboxamide ribofuranoside (AICAR) and adenosine. Using pharmacologic inhibitors and genetic knockdowns of purine metabolic enzymes, we establish that TXNIP indu...
Source: BJ Gene - May 1, 2013 Category: Biochemistry Authors: K Han, D E Ayer Tags: BJ Metabolism Source Type: research
Lipin1 regulates PPAR{gamma} transcriptional activity
Peroxisome proliferator-activated receptor-γ (PPARγ) is a master transcription factor involved in adipogenesis through regulating adipocyte-specific gene expression. Recently, lipin1 is known to act as a key factor for the adipocyte maturation and maintenance with modulating C/EBPα and PPARγ network. However, the precise mechanism by which lipin1 affects transcriptional activity of PPARγ is largely unknown. The present study revealed that lipin1 activates PPARγ by releasing corepressors, nuclear receptor corepressor 1 (NcoR1) and silencing mediator of retinoid and thyroid hormone r...
Source: BJ Gene - April 30, 2013 Category: Biochemistry Authors: H Kim, E Bae, D Jeong, M Kim, W Jin, S Park, G Han, G Carman, E Koh, K Kim Tags: BJ Metabolism Source Type: research
Mechanistic insights into small RNA recognition and modification by the HEN1 methyltransferase
The HEN1 methyltransferase from Arabidopsis thaliana modifies the 3'-terminal nucleotides of small regulatory RNAs. Although it is one of the best characterized members of the 2’-O-methyltransferase family, many aspects of its interactions with the cofactor and substrate RNA remained unresolved. To better understand substrate interactions and contributions of individual steps during HEN1 catalysis, we studied binding and methylation kinetics using series of unmethylated, hemimethylated and doubly methylated miRNA and siRNA substrates. Our studies indicate that HEN1 specifically binds double-stranded unmethylated or ...
Source: BJ Gene - April 29, 2013 Category: Biochemistry Authors: A Plotnikova, S Baranauskė, A Osipenko, S Klimašauskas, G Vilkaitis Tags: BJ Gene Source Type: research
A Covalent Protein-DNA 5'-Product Adduct is Generated Following AP Lyase Activity of Human AlkB Homolog 1 (ALKBH1)
ALKBH1 is a mammalian AlkB homolog that possesses abasic site (AP) lyase activity. The AP lyase reaction is catalyzed by imine formation with an active site Lys, and a covalent intermediate can be trapped in the presence of NaBH4. Surprisingly, ALKBH1 also forms a stable protein-DNA adduct in the absence of a reducing agent. Experiments with different substrates demonstrated that the protein covalently binds to the 5' DNA product; i.e., the fragment containing an α,β-unsaturated aldehyde. The amino terminal domain of ALKBH1 was identified as the main site of linkage with DNA. By contrast, mutagenesis studies ...
Source: BJ Gene - April 12, 2013 Category: Biochemistry Authors: T A. Müller, M M. Andrzejak, R P. Hausinger Tags: BJ Gene Source Type: research
Structural and Functional Interactions of the Prostate Cancer Suppressor NKX3.1 with Topoisomerase I
NKX3.1 is a prostate tumor suppressor protein that binds to topoisomerase I and enhances its DNA cleavage activity. We show that the NKX3.1 homeodomain binds to a region of topoisomerase I spanning the junction between core and linker domains. NKX3.1 activated N-terminal truncated topoisomerase I (Topo70) in vitro. In contrast, NKX3.1 interacts with the enzyme reconstituted from peptide fragments of core domain and linker-active site domains, but inhibits the DNA unwinding activity of the reconstituted enzyme in vitro. The effect of NKX3.1 on both Topo70 and the reconstituted enzyme was seen in the presence and absence of ...
Source: BJ Gene - April 5, 2013 Category: Biochemistry Authors: L Song, C Bowen, E P Gelmann Tags: BJ Biomolecules Source Type: research
Role of the unstructured N-terminal domain of the human Apurinic/Apyrimidinic Endonuclease 1 (hAPE1) in the modulation of its interaction with nucleic acids and Nucleophosmin (NPM1)
The human Apurinic/apyrimidinic endonuclease 1 (hAPE1) is an essential enzyme, being the main abasic endonuclease in higher eukaryotes. However, many evidences show that hAPE1 can directly bind specific gene promoters, thus modulating their transcriptional activity, even in the absence of specific DNA damage. Recent findings, moreover, suggest a role for hAPE1 in RNA processing, which is modulated by the interaction with Nucleophosmin (NPM1). Independent domains account for many activities of hAPE1; however, while the endonuclease and the redox-active portions of the protein are well characterized, a better understanding o...
Source: BJ Gene - April 2, 2013 Category: Biochemistry Authors: M Poletto, C Vascotto, P L. Scognamiglio, L Lirussi, D Marasco, G Tell Tags: BJ Gene Source Type: research
