Regulation of Streptomyces Chitinases by Two-Component Signal Transduction Systems and their Post Translational Modifications: A Review

This article reviews the developments related to Streptomyces chitinases regulation and their post translational modifications. Chitinases are enzymes which cleave chitin, a polymer of N-acetylglucosamine to its monomer. Bacteria produce chitinases to fulfil their nutritional needs since by-products of chitin degradation can serve as a source of carbon and nitrogen. Chitinolytic bacteria such as Streptomyces produce multiple chitinases which act synergistically to degrade crystalline form of chitin. Streptomyces are one of the major producers of chitinases in the soil. Every Streptomyces genome sequenced till date has multiple genes for chitinases. The chitinases resulting from proteolytic cleavage have different specific activities and binding efficiency. Both of the above mentioned factors contribute to complexity of the chitinolytic system. Two component systems (TCS) are the predominant signal transduction system in bacteria that regulate a wide variety of behaviours as well as fundamental processes such as metabolism and motility. Bacteria generally use two-component signal transduction pathways to couple environmental stimuli to adaptive responses. Apart from the generalized behaviours they also regulate specialised processes such as development and virulence. Thus this review focuses on the two component systems of Streptomyces, their mechanism of action, regulation of chitinases by TCS and post-translational modifications

Spoligotyping, phenotypic and genotypic characterization of katG, rpoB gene of M. tuberculosis isolates from Sahariya tribe of Madhya Pradesh India

Background: Sahariya, a primitive tribal group, residing in Gwalior and Sheopur districts of Madhya Pradesh, India, show high incidence and prevalence of pulmonary tuberculosis (PTB). The study was designed to understand the genetic diversity and phenotype — genotype association of drug resistant M. tuberculosis strains, infecting Sahariya tribe. Materials and methods: A total of 103 pulmonary tuberculosis patients from Sahariya tribe were recruited from Gwalior and Sheopur districts. Sputum samples were collected and cultured on LJ slants and drug sensitivity tests were carried out. Genomic DNA was extracted, followed by spoligotyping and genotyping of drug target genes, katG and rpoB, using MAS-PCR, PCR-RFLP and DNA sequencing. Result: Seventeen different spoligotypes were identified, in which, EAI3_IND/ST11 M. tuberculosis strain appeared predominant, followed by CAS1_Delhi/ST26. Results of our phenotypic drug susceptibility test identified high incidence (12.6%) of isoniazid-resistant tuberculosis, while 4.85% isolates were multi drug resistant (MDR). Further genotyping of drug target genes identified 8.7% of isoniazid-R isolates to have a mutation at katG codon 463, while 3.8% isolates showed mutations at two sites, katG codons 315 and 463. In case of MDR-TB isolates, all from CAS lineage, 3.85% had mutations on katG and rpoB genes, at codon 463 and codon 526, respectively, while 0.97% isolates were harbouring mutations at codons 315, 463 and 531. Conclusion: Our findings have revealed that EAI3_IND strain is the predominant strain infecting Sahariya. The incidence of isoniazid-R M. tuberculosis strain infection is high, with an increased propensity to evolve into MDR-TB. Therefore, the TB centres should also consider isoniazid-R status of the isolates along with CBNAAT before deciding the drug regimen for the patients. Keywords: Isoniazid resistance, Multi-drug resistance, M. tuberculosis, Sahariya tribe, Spoligotypin

A New Intergenic α -Globin Deletion ( α – α Δ125 ) Found in a Kabyle Population

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Dataset for the spore surface proteome and hydrophobin A/RodA proteoforms of A.flavus

Fungal keratitis is a major sight-threatening corneal infection: and mycotic keratitis is more common in tropical parts of the world including India. Aspergillus flavus and Fusarium are the predominant causative agents of corneal infection. We extracted conidial surface proteins of A. flavus from saprophyte and clinical isolates and analyzed the proteins using high resolution mass spectrometry. The data revealed ecotype specific alteration in surface proteome since the proteome profile of the clinical isolates and saprophyte showed significant differences. Detailed examination of the mass spec data of RodA proteins extracted from polyacrylamide gels revealed the presence of two proteoforms of this protein. We also identified the mechanism of formation of these two isoforms. Detailed analysis of this data and the conclusions derived are described in the article, “Identification of the proteoforms of surface localized Rod A of A. flavus and determination of the mechanism of proteoform generation” [1]

Mechanisms of Chronic Alcohol Exposure-Induced Aggressiveness in Cellular Model of HCC and Recovery after Alcohol Withdrawal.

International audienceAlcohol-related liver disease is the most prevalent chronic liver disease worldwide, accounting for 30% of hepatocellular carcinoma (HCC) cases and HCC-specific deaths. However, the knowledge on mechanisms by which alcohol consumption leads to cancer progression and its aggressiveness is limited. Better understanding of the clinical features and the mechanisms of alcohol-induced HCC are of critical importance for prevention and the development of novel treatments. Early stage Huh-7 and advanced SNU449 liver cancer cell lines were subjected to chronic alcohol exposure (CAE), at different doses for 6~months followed by 1-month alcohol withdrawal period. ADH activity and ALDH expression were much lower in SNU449 compared with Huh-7 cells and at the 270~mM dose, CAE decreased cell viability by about 50% and 80%, respectively, in Huh-7 and SNU449 cells but induced mortality only in Huh-7 cells. Thus, Huh-7 may be more vulnerable to ethanol toxicity because of the higher levels of acetaldehyde. CAE induced a dose-dependent increase in cell migration and invasion and also in the expression of cancer stem cells markers (CD133, CD44, CD90). CAE in Huh-7 cells selectively activated ERK1/2 and inhibited GSK3β signaling pathways. Most of the changes induced by CAE were reversed after alcohol withdrawal. Interestingly, we confirmed the increase in CD133 mRNA levels in the tumoral tissue of patients with ethanol-related HCC compared to other HCC etiologies. Our results may explain the benefits observed in epidemiological studies showing a significant increase of overall survival in abstinent compared with non-abstinent patients

Hepatocyte SLAMF3 reduced specifically the multi-drugs resistance protein MRP-1 and increases HCC cells sensitization to anti-cancer drugs

International audienceMultidrug resistance MDR proteins (MRPs) are members of the C family of a group of proteins named ATP binding cassette (ABC) transporters. MRPs can transport drugs including anticancer drugs, nucleoside analogs, antimetabolites and tyrosine kinase inhibitors. Drugs used in HCC therapy, such as tyrosine kinase inhibitor sorafenib, are substrates of uptake and/or efflux transporters. Variable expression of MRPs at the plasma membrane of tumor cells may contribute to drug resistance and subsequent clinical response. Recently, we reported that the hepatocyte SLAMF3 expression (Signaling Lymphocytic Activation Molecule Family member 3) was reduced in tumor cells from hepatocellular carcinoma (HCC) compared to its high expression in adjacent tissues. In the present study, we make a strong correlation between induced SLAMF3 overexpression and the specific loss of MRP-1 expression and its functionalities as a drugs resistance transporter. No changes were observed on expression of ABCG2 and MDR. More importantly, we highlight a strong inverse correlation between MRP-1 and SLAMF3 expression in patients with HCC. We propose that the SLAMF3 overexpression in cancerous cells could represent a potential therapeutic strategy to improve the drugs sensibility of resistant cells and thus control the therapeutic failure in HCC patients

Click-Crosslinked Injectable Gelatin Hydrogels

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RB/PLK1-dependent induced pathway by SLAMF3 expression inhibits mitosis and control hepatocarcinoma cell proliferation

International audiencePolo-like kinase PLK1 is a cell cycle protein that plays multiple roles in promoting cell cycle progression. Among the many roles, the most prominent role of PLK1 is to regulate the mitotic spindle formation checkpoint at the M-phase. Recently we reported the expression of SLAMF3 in Hepatocytes and show that it is down regulated in tumor cells of hepatocellular carcinoma (HCC). We also show that the forced high expression level of SLAMF3 in HCC cells controls proliferation by inhibiting the MAPK ERK/JNK and the mTOR pathways. In the present study, we provide evidence that the inhibitory effect of SLAMF3 on HCC proliferation occurs through Retinoblastoma (RB) factor and PLK1-dependent pathway. In addition to the inhibition of MAPK ERK/JNK and the mTOR pathways, expression of SLAMF3 in HCC retains RB factor in its hypophosphorylated active form, which in turn inactivates E2F transcription factor, thereby repressing the expression and activation of PLK1. A clear inverse correlation was also observed between SLAMF3 and PLK expression in patients with HCC. In conclusion, the results presented here suggest that the tumor suppressor potential of SLAMF3 occurs through activation of RB that represses PLK1. We propose that the induction of a high expression level of SLAMF3 in cancerous cells could control cellular mitosis and block tumor progression

Severe phenotypic spectrum of biallelic mutations in PRRT2 gene

International audienceBACKGROUND:Heterozygous dominant mutations of PRRT2 have been associated with various types of paroxysmal neurological manifestations, including benign familial infantile convulsions and paroxysmal kinesigenic dyskinesia. The phenotype associated with biallelic mutations is not well understood as few cases have been reported.METHODS:PRRT2 screening was performed by Sanger sequencing and quantitative multiplex PCR of short fluorescent fragments. A CGH array was used to characterise the size of the deletion at the 16p11.2 locus.RESULTS:Five patients with homozygous or compound heterozygous deleterious PRRT2 gene mutations are described. These patients differ from those with a single mutation by their overall increased severity: (1) the combination of at least three different forms of paroxysmal neurological disorders within the same patient and persistence of paroxysmal attacks; (2) the occurrence of uncommon prolonged episodes of ataxia; and (3) the association of permanent neurological disorders including learning difficulties in four patients and cerebellar atrophy in 2.CONCLUSIONS:Our observations expand the phenotype related to PRRT2 insufficiency, and highlight the complexity of the phenotype associated with biallelic mutations, which represents a severe neurological disease with various paroxysmal disorders and frequent developmental disabilities