AKAP13 couples GPCR signaling to mTORC1 inhibition

The mammalian target of rapamycin complex 1 (mTORC1) senses multiple stimuli to regulate anabolic and catabolic processes. mTORC1 is typically hyperactivated in multiple human diseases such as cancer and type 2 diabetes. Extensive research has focused on signaling pathways that can activate mTORC1 such as growth factors and amino acids. However, less is known about signaling cues that can directly inhibit mTORC1 activity. Here, we identify A-kinase anchoring protein 13 (AKAP13) as an mTORC1 binding protein, and a crucial regulator of mTORC1 inhibition by G-protein coupled receptor (GPCR) signaling. GPCRs paired to Gα_s proteins increase cyclic adenosine 3’5’ monophosphate (cAMP) to activate protein kinase A (PKA). Mechanistically, AKAP13 acts as a scaffold for PKA and mTORC1, where PKA inhibits mTORC1 through the phosphorylation of Raptor on Ser 791. Importantly, AKAP13 mediates mTORC1-induced cell proliferation, cell size, and colony formation. AKAP13 expression correlates with mTORC1 activation and overall lung adenocarcinoma patient survival, as well as lung cancer tumor growth in vivo. Our study identifies AKAP13 as an important player in mTORC1 inhibition by GPCRs, and targeting this pathway may be beneficial for human diseases with hyperactivated mTORC1.     

Identification and assignment of function to the genes of Aspergillus fumigatus expressed at 37 degrees C

Aspergillus fumigatus, a fungal pathogen, causes a spectrum of allergic and invasive disorders. In order to rapidly identify genes of this fungus relevant for pathogenesis and as potential antifungal drug targets, 125 expressed sequence tags (ESTs) were generated from 200 phage clones of a non-normalized cDNA library. Out of a novel 68 ESTs, 45 were assigned putative functions based on the sequence similarity. The identities of some of these genes suggest that they may be involved in pathogenesis or autoimmune reactions. Additional genes were identified that are possible targets for the development of antifungal drugs or that may be of use in diagnosing fungal infections.     

Species- and strain-specific probes derived from repetitive DNA for distinguishing Entamoeba histolytica and Entamoeba dispar

Entamoeba histolytica and Entamoeba dispar are two morphologically indistinguishable species that are found in the human gut. Of the two, E. histolytica is considered to be pathogenic while E. dispar is nonpathogenic. To generate molecular probes to detect and distinguish between the two species, we utilized repeat sequences present in Entamoeba genome. We have developed probes and primers from rDNA episomes, and unidentified Entamoeba EST1 repeat for this purpose, and used them for dot blot hybridization and PCR amplification. To investigate the possible existence of invasive and noninvasive strains of E. histolytica, the ability to differentiate individual isolates is necessary. For this purpose, we have utilized a modification of the AFLP procedure called 'Transposon display,' which generates and displays large number of genomic bands associated with a transposon. We have used the abundant retrotransposon, EhSINE1, for this purpose,and demonstrated its potential as a marker to study strain variation in E. histolytica. This technique could suitably be employed in carrying out significant molecular epidemiological studies and large-scale typing of this parasite.     

Comparative Gene Expression Analyses Identify Luminal and Basal Subtypes of Canine Invasive Urothelial Carcinoma That Mimic Patterns in Human Invasive Bladder Cancer

More than 160,000 people are expected to die from invasive urothelial carcinoma (iUC) this year worldwide. Research in relevant animal models is essential to improving iUC management. Naturally-occurring canine iUC closely resembles human iUC in histopathology, metastatic behavior, and treatment response, and could provide a relevant model for human iUC. The molecular characterization of canine iUC, however, has been limited. Work was conducted to compare gene expression array results between tissue samples from iUC and normal bladder in dogs, with comparison to similar expression array data from human iUC and normal bladder in the literature. Considerable similarities between enrichment patterns of genes in canine and human iUC were observed. These included patterns mirroring basal and luminal subtypes initially observed in human breast cancer and more recently noted in human iUC. Canine iUC samples also exhibited enrichment for genes involved in P53 pathways, as has been reported in human iUC. This is particularly relevant as drugs targeting these genes/pathways in other cancers could be repurposed to treat iUC, with dogs providing a model to optimize therapy. As part of the validation of the results and proof of principal for evaluating individualized targeted therapy, the overexpression of EGFR in canine bladder iUC was confirmed. The similarities in gene expression patterns between dogs and humans add considerably to the value of naturally-occurring canine iUC as a relevant and much needed animal model for human iUC. Furthermore, the finding of expression patterns that cross different pathologically-defined cancers could allow studies of dogs with iUC to help optimize cancer management across multiple cancer types. The work is also expected to lead to a better understanding of the biological importance of the gene expression patterns, and the potential application of the cross-species comparisons approach to other cancer types as well.     

Genetic Acquisition of NDM Gene Offers Sustainability among Clinical Isolates of Pseudomonas aeruginosa in Clinical Settings

New Delhi metallo β-lactamases are one of the most significant emerging resistance determinants towards carbapenem drugs. Their persistence and adaptability often depends on their genetic environment and linkage. This study reports a unique and novel arrangement of bla _NDM-1 gene within clinical isolates of Pseudomonas aeruginosa from a tertiary referral hospital in north India. Three NDM positive clonally unrelated clinical isolates of P. aeruginosa were recovered from hospital patients. Association of integron with bla _NDM-1 and presence of gene cassettes were assessed by PCR. Genetic linkage of NDM gene with ISAba125 was determined and in negative cases linkage in upstream region was mapped by inverse PCR. In which only one isolate’s NDM gene was linked with ISAba125 for mobility, while other two reveals new genetic arrangement and found to be inserted within DNA directed RNA polymerase gene of the host genome detected by inverse PCR followed by sequencing analysis. In continuation significance of this novel linkage was further analyzed wherein promoter site detected by Softberry BPROM software and activity were assessed by cloning succeeding semi-quantitative RT-PCR indicating the higher expression level of NDM gene. This study concluded out that the unique genetic makeup of NDM gene with DNA-dependent-RNA-polymerase favours adaptability to the host in hospital environment against huge antibiotic pressure.     

Assessment of genetic diversity in indigenous turmeric (Curcuma longa) germplasm from India using molecular markers

Curcuma longa L., commonly known as turmeric, is one of the economically and medicinally important plant species. It is predominantly cultivated in the tropical and sub tropical countries. India is the largest producer, and exporter of turmeric in the world, followed by China, Indonesia, Bangladesh and Thailand. In the present study, Directed Amplification of Minisatellite DNA (DAMD) and Inter Simple Sequence Repeats (ISSR), methods were used to estimate the genetic variability in indigenous turmeric germplasm. Cumulative data analysis for DAMD (15) and ISSR (13) markers resulted into 478 fragments, out of which 392 fragments were polymorphic, revealing 82 % polymorphism across the turmeric genotypes. Wide range of pairwise genetic distances (0.03–0.59) across the genotypes revealed that these genotypes are genetically quite diverse. The UPGMA dendrogram generated using cumulative data showed significant relationships amongst the genotypes. All 29 genotypes studied grouped into two clusters irrespective of their geographical affiliations with 100 % bootstrap value except few genotypes, suggesting considerable diversity amongst the genotypes. These results suggested that the current collection of turmeric genotypes preserve the vast majority of natural variations. The results further demonstrate the efficiency and reliability of DAMD and ISSR markers in determining the genetic diversity and relationships among the indigenous turmeric germplasm. DAMD and ISSR profiling have identified diverse turmeric genotypes, which could be further utilized in various genetic improvement programmes including conventional as well as marker assisted breeding towards development of new and desirable turmeric genotypes.     

A simple Pichia pastoris fermentation and downstream processing strategy for making recombinant pandemic Swine Origin Influenza A virus Hemagglutinin protein

The present Influenza vaccine manufacturing process has posed a clear impediment to initiation of rapid mass vaccination against spreading pandemic influenza. New vaccine strategies are therefore needed that can accelerate the vaccine production. Pichia offers several advantages for rapid and economical bulk production of recombinant proteins and, hence, can be attractive alternative for producing an effective influenza HA based subunit vaccine. The recombinant Pichia harboring the transgene was subjected to fed-batch fermentation at 10 L scale. A simple fermentation and downstream processing strategy is developed for high-yield secretory expression of the recombinant Hemagglutinin protein of pandemic Swine Origin Influenza A virus using Pichia pastoris via fed-batch fermentation. Expression and purification were optimized and the expressed recombinant Hemagglutinin protein was verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blot and MALDI-TOF analysis. In this paper, we describe a fed-batch fermentation protocol for the secreted production of Swine Influenza A Hemagglutinin protein in the P. pastoris GS115 strain. We have shown that there is a clear relationship between product yield and specific growth rate. The fed-batch fermentation and downstream processing methods optimized in the present study have immense practical application for high-level production of the recombinant H1N1 HA protein in a cost effective way using P. pastoris.     

Characterization of two metagenome-derived esterases that reactivate chloramphenicol by counteracting chloramphenicol acetyltransferase

Function-driven metagenomic analysis is a powerful approach to screening for novel biocatalysts. In this study, we investigated lipolytic enzymes selected from an alluvial soil metagenomic library, and identified two novel esterases, EstDL26 and EstDL136. EstDL26 and EstDL136 reactivated chloramphenicol from its acetyl derivates by counteracting the chloramphenicol acetyltransferase (CAT) activity in Escherichia coli. These two enzymes showed only 27% identity in amino acid sequence to each other; however both preferentially hydrolyzed short-chain p-nitrophenyl esters (< or =C5) and showed mesophilic properties. In vitro, EstDL136 catalyzed the deacetylation of 1- and 3- acetyl and 1,3-diacetyl derivates; in contrast, EstDL26 was not capable of the deacetylation at C1, indicating a potential regioselectivity. EstDL26 and EstDL136 were similar to microbial hormone-sensitive lipase (HSL), and since chloramphenicol acetate esterase (CAE) activity was detected from two other soil esterases in the HSL family, this suggests a distribution of CAE among the soil microorganisms. The isolation and characterization of EstDL26 and EstDL136 in this study may be helpful in understanding the diversity of CAE enzymes and their potential role in releasing active chloramphenicol in the producing bacteria.