Protein–Protein Interactions and Quantitative Phosphoproteomic Analysis Reveal Potential Mitochondrial Substrates of Protein Phosphatase 2A-B’ζ Holoenzyme

Protein phosphatase 2A (PP2A) is a heterotrimeric conserved serine/threonine phosphatase complex that includes catalytic, scaffolding, and regulatory subunits. The 3 A subunits, 17 B subunits, and 5 C subunits that are encoded by the Arabidopsis genome allow 255 possible PP2A holoenzyme combinations. The regulatory subunits are crucial for substrate specificity and PP2A complex localization and are classified into the B, B’, and B” non-related families in land plants. In Arabidopsis, the close homologs B’η, B’θ, B’γ, and B’ζ are further classified into a subfamily of B’ called B’η. Previous studies have suggested that mitochondrial targeted PP2A subunits (B’ζ) play a role in energy metabolism and plant innate immunity. Potentially, the PP2A-B’ζ holoenzyme is involved in the regulation of the mitochondrial succinate/fumarate translocator, and it may affect the enzymes involved in energy metabolism. To investigate this hypothesis, the interactions between PP2A-B’ζ and the enzymes involved in the mitochondrial energy flow were investigated using bimolecular fluorescence complementation in tobacco and onion cells. Interactions were confirmed between the B’ζ subunit and the Krebs cycle proteins succinate/fumarate translocator (mSFC1), malate dehydrogenase (mMDH2), and aconitase (ACO3). Additional putative interacting candidates were deduced by comparing the enriched phosphoproteomes of wild type and B’ζ mutants: the mitochondrial regulator Arabidopsis pentatricopeptide repeat 6 (PPR6) and the two metabolic enzymes phosphoenolpyruvate carboxylase (PPC3) and phosphoenolpyruvate carboxykinase (PCK1). Overall, this study identifies potential PP2A substrates and highlights the role of PP2A in regulating energy metabolism in mitochondria.publishedVersio

Multi-targeted trehalose-6-phosphate phosphatase I harbors a novel peroxisomal targeting signal 1 and is essential for flowering and development

A putative, non-canonical peroxisomal targeting signal type 1 (PTS1) Pro-Arg-Met > was identified in the extreme C-terminus of trehalose-6-phosphate phosphatase (TPP)I. TPP catalyzes the final step of trehalose synthesis, and the enzyme was previously characterized to be nuclear only (Krasensky et al. in Antioxid Redox Signal 21(9):1289–1304, 2014). Here we show that the TPPI C-terminal decapeptide ending with Pro-Arg-Met > or Pro-Lys-Met > can indeed function as a PTS1. Upon transient expression in two plant expression systems, the free C- or N-terminal end led to the full-length TPPI targeting to peroxisomes and plastids, respectively. The nucleus and nucleolus targeting of the full-length TPPI was observed in both cases. The homozygous T-DNA insertion line of TPPI showed a pleiotropic phenotype including smaller leaves, shorter roots, delayed flowering, hypersensitivity to salt, and a sucrose dependent seedling development. Our results identify novel PTS1s, and TPPI as a protein multi-targeted to peroxisomes, plastids, nucleus, and nucleolus. Altogether our findings implicate an essential role for TPPI in development, reproduction, and cell signaling.publishedVersio

Cytoprotective and Antioxidants in Peroxisomal Neurodegenerative Diseases

Several of the peroxisomal neurodegenerative disorders are the consequence of a specific deficiency of an enzyme or a transporter involved in peroxisomal beta-oxidation of very long chain fatty acids [1,2]. One of the hallmarks in these peroxisomal rare neurodegenerative diseases and in other common demyelinating disorders is the accompanying oxidative damage and neuroinflammation [3]. Compelling data indicates that oxidative stress can activate microglia leading to the overproduction of pro-inflammatory molecules [4,5]. Thus, targeting oxidative stress to limit neuroinflammation may open a new pharmacological therapy window for these still incurable devastating peroxisomal diseases. Here, we present different natural (resveratrol) [6] and synthetic (organoselenides) [7] antioxidant compounds for their capacity of scavenging oxidative stress and in the perspective therapeutic use against oxidative damage in peroxisomal disorders

GPC3 gene expression and allelic discrimination of FZD7 gene in Egyptian patients with hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide, and especially in Egypt. Early diagnosis of HCC greatly improves the survival and prognosis of patients. Low sensitivity and specificity of alpha-fetoprotein (AFP) has led to the demand for novel biomarkers of HCC. The aim of the present study was to evaluate the validity of frizzled-7 (FZD7) and glypican-3 (GPC3) gene expression as potential biomarkers for HCC early diagnosis, and to investigate the association between FZD7 rs2280509 polymorphism and HCC risk. Materials and methods: Quantification of FZD7 and GPC3 gene expression by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay, and genotyping FZD 7 (rs2280509 SNP) gene polymorphism using RT-PCR. Results: The current results revealed that FZD7 gene expression had a greater area under the curve (AUC) for identifying HCC than GPC3 gene expression and AFP levels. The combination of the three markers as a panel showed a better diagnostic performance with a greater AUC than any of the single markers alone (p < 0.05). The FZD7 rs2280509 polymorphism (CT) was found to be significantly associated with an increased risk of HCC. The CT genotype and T allele were significantly more prevalent in the HCC group compared to either the cirrhosis (p = 0.03) or control groups (p = 0.0009 and 0.002; respectively). Conclusion: FZD7 and GPC3 gene expressions have a complementary role in early HCC detection, with a greater diagnostic sensitivity and accuracy than AFP. In addition, FZD7 rs2280509 polymorphism is significantly associated with an increased risk of HCC in the Egyptian population

Protein-Protein Interactions and Quantitative Phosphoproteomic Analysis Reveal Potential Mitochondrial Substrates of Protein Phosphatase 2A-B'& zeta; Holoenzyme

Protein phosphatase 2A (PP2A) is a heterotrimeric conserved serine/threonine phosphatase complex that includes catalytic, scaffolding, and regulatory subunits. The 3 A subunits, 17 B subunits, and 5 C subunits that are encoded by the Arabidopsis genome allow 255 possible PP2A holoenzyme combinations. The regulatory subunits are crucial for substrate specificity and PP2A complex localization and are classified into the B, B', and B" non-related families in land plants. In Arabidopsis, the close homologs B'& eta;, B'& theta;, B'& gamma;, and B'& zeta; are further classified into a subfamily of B' called B'& eta;. Previous studies have suggested that mitochondrial targeted PP2A subunits (B'& zeta;) play a role in energy metabolism and plant innate immunity. Potentially, the PP2A-B'& zeta; holoenzyme is involved in the regulation of the mitochondrial succinate/fumarate translocator, and it may affect the enzymes involved in energy metabolism. To investigate this hypothesis, the interactions between PP2A-B'& zeta; and the enzymes involved in the mitochondrial energy flow were investigated using bimolecular fluorescence complementation in tobacco and onion cells. Interactions were confirmed between the B'& zeta; subunit and the Krebs cycle proteins succinate/fumarate translocator (mSFC1), malate dehydrogenase (mMDH2), and aconitase (ACO3). Additional putative interacting candidates were deduced by comparing the enriched phosphoproteomes of wild type and B'& zeta; mutants: the mitochondrial regulator Arabidopsis pentatricopeptide repeat 6 (PPR6) and the two metabolic enzymes phosphoenolpyruvate carboxylase (PPC3) and phosphoenolpyruvate carboxykinase (PCK1). Overall, this study identifies potential PP2A substrates and highlights the role of PP2A in regulating energy metabolism in mitochondria

A lightweight incremental analysis and profiling framework for embedded devices

International audienceEmbedded systems such as mobile devices are currently ubiquitous. The performance potential of these devices is rapidly improving by incorporating multi-core and GPU technologies, and is rapidly catching up with the workstation platforms. Nevertheless, the heterogeneity of the underlying hardware as well as the low-power constraints severely limit performance portability. In this paper we consider the case of leveraging JIT compilers to provide portable parallelization while hiding the corresponding expensive runtime analysis. We propose a novel lightweight JIT framework that exploits the device idle time and the large storage space generally available on these devices. The framework performs 'incremental' analysis while the processor is idle (such as during charging time), and exploits the storage space to cache intermediate analysis results. Such approach requires reengineering existing complex optimization analysis methods. For this paper, we focus on the traditional loop parallelization analysis, and implement a working prototype into the LLVM framework, integrating a lightweight dynamic profiling method to identify hotspots. Initial results demonstrate the low overhead of our method for parallelizing simple loops on an embedded GPU

Is LigaSure a safe cystic duct sealer? An ex vivo study

To compare the efficacy and safety of both mechanical methods (clips) and electrosurgical instruments, harmonic scalpel (HS) and LigaSure (LS), for securing the cystic duct during laparoscopic cholecystectomy (LC). During the study period from October 2010 to October 2012, 458 patients with gallbladder stones underwent LC. A total of 38 patients were excluded from the study for different reasons. The gallbladder was excised laparoscopically through the traditional method. The gallbladder specimens of the patients were divided into three equal groups randomly, and the distal part of the cystic duct was sealed ex vivo using ligaclips (Group A), HS (Group B), and LS (Group C). The gallbladders were then connected to a pneumatic tourniquet device and we very gradually increased the pressure with air. The bursting pressure of the cystic duct (CDBP) was measured and differences between the three groups were calculated. The mean CDBP was 329.7 ± 38.8 mmHg in the ligaclip group, 358.0 ± 33.1 mmHg in the HS group, and 219.7 ± 41.2 mmHg in the LS group. A comparison of the mean CDBP between the groups indicated the superiority of HS over ligaclip and LS. CDBP was significantly higher in the ligaclips group compared with the LS group (p 195 mmHg) than the maximum common bile duct pressure, whereas for LS the CDBP range was 150–297 mmHg, indicating that it is not safe for sealing. HS is a safe alternative to clips. In fact, it was even safer than clips. By contrast, LS is not safe for cystic duct sealing

Bio-diagnostic performances of microRNAs set related to DNA damage response pathway among hepatitis C virus-associated hepatocellular carcinoma patients

Abstract Background Up to date, a well-defined microRNAs (miRNAs) profile involved in hepatocellular carcinoma (HCC) pathogenesis remains indecisive. Thus, employing miRNAs for HCC diagnosis is demanded for early therapeutic interventions. We aimed to evaluate the usage of miRNAs set related to the SuperPath: miRNAs involved in DNA damage response pathway as effective biomarkers for HCV-related HCC diagnosis. Results The study enrolled 97 patients with HCV-related HCC, 84 with hepatitis C virus (HCV), 97 with liver cirrhosis (LC), and 84 healthy individuals. Serum miRNA-23a, miRNA-203, miRNA-100-5p, and miRNA-16 were quantified using qRT-PCR experiments, AFP and routine LFTs were estimated via standard techniques. Pathway enrichment analysis along with the construction of miRNAs regulatory network were performed. With respect to healthy individuals, miRNA-203, miRNA-100-5p, and miRNA-16 were significantly downregulated in HCC, HCV, and LC groups, while miRNA-23a showed significant upregulation (p  5 cm. Additionally, the diagnostic performance of miRNA-23a expression level at a selected cut-off value of 3.99 overtakes AFP, while expressions of miR-203, miRNA-100-5p, and miRNA-16 represent poor diagnostic outcomes. Conclusions Keeping in mind the individual variability and high level of heterogeneity in HCC, our data revealed the diagnostic value of miRNA-23a expression in HCV-related HCC patients. Further extra in silico HCC-specific microRNAs sets are demanded in diagnosis

Is LigaSure a safe cystic duct sealer? An ex vivo study

Background: To compare the efficacy and safety of both mechanical methods (clips) and electrosurgical instruments, harmonic scalpel (HS) and LigaSure (LS), for securing the cystic duct during laparoscopic cholecystectomy (LC). Methods: During the study period from October 2010 to October 2012, 458 patients with gallbladder stones underwent LC. A total of 38 patients were excluded from the study for different reasons. The gallbladder was excised laparoscopically through the traditional method. The gallbladder specimens of the patients were divided into three equal groups randomly, and the distal part of the cystic duct was sealed ex vivo using ligaclips (Group A), HS (Group B), and LS (Group C). The gallbladders were then connected to a pneumatic tourniquet device and we very gradually increased the pressure with air. The bursting pressure of the cystic duct (CDBP) was measured and differences between the three groups were calculated. Results: The mean CDBP was 329.7 ± 38.8 mmHg in the ligaclip group, 358.0 ± 33.1 mmHg in the HS group, and 219.7 ± 41.2 mmHg in the LS group. A comparison of the mean CDBP between the groups indicated the superiority of HS over ligaclip and LS. CDBP was significantly higher in the ligaclips group compared with the LS group (p 195 mmHg) than the maximum common bile duct pressure, whereas for LS the CDBP range was 150–297 mmHg, indicating that it is not safe for sealing. Conclusion: HS is a safe alternative to clips. In fact, it was even safer than clips. By contrast, LS is not safe for cystic duct sealing

Cytoprotective and Antioxidants in Peroxisomal Neurodegenerative Diseases

Several of the peroxisomal neurodegenerative disorders are the consequence of a specific deficiency of an enzyme or a transporter involved in peroxisomal beta-oxidation of very long chain fatty acids [1,2]. One of the hallmarks in these peroxisomal rare neurodegenerative diseases and in other common demyelinating disorders is the accompanying oxidative damage and neuroinflammation [3]. Compelling data indicates that oxidative stress can activate microglia leading to the overproduction of pro-inflammatory molecules [4,5]. Thus, targeting oxidative stress to limit neuroinflammation may open a new pharmacological therapy window for these still incurable devastating peroxisomal diseases. Here, we present different natural (resveratrol) [6] and synthetic (organoselenides) [7] antioxidant compounds for their capacity of scavenging oxidative stress and in the perspective therapeutic use against oxidative damage in peroxisomal disorders