TGF-β regulates LARG and GEF-H1 during EMT to affect stiffening response to force and cell invasion

Recent studies implicate a role for cell mechanics in cancer progression. The epithelial-to-mesenchymal transition (EMT) regulates the detachment of cancer cells from the epithelium and facilitates their invasion into stromal tissue. Although classic EMT hallmarks include loss of cell–cell adhesions, morphology changes, and increased invasion capacity, little is known about the associated mechanical changes. Previously, force application on integrins has been shown to initiate cytoskeletal rearrangements that result in increased cell stiffness and a stiffening response. Here we demonstrate that transforming growth factor β (TGF-β)–induced EMT results in decreased stiffness and loss of the normal stiffening response to force applied on integrins. We find that suppression of the RhoA guanine nucleotide exchange factors (GEFs) LARG and GEF-H1 through TGF-β/ALK5–enhanced proteasomal degradation mediates these changes in cell mechanics and affects EMT-associated invasion. Taken together, our results reveal a functional connection between attenuated stiffness and stiffening response and the increased invasion capacity acquired after TGF-β–induced EMT.     

Halocin SH10 production by an extreme haloarchaeon Natrinema sp. BTSH10 isolated from salt pans of South India

Halobacteria, members of the domain Archaea that live under extremely halophilic conditions, are often considered as dependable source for deriving novel enzymes, novel genes, bioactive compounds and other industrially important molecules. Protein antibiotics have potential for application as preserving agents in food industry, leather industry and in control of infectious bacteria. Halocins are proteinaceous antibiotics synthesized and released into the environment by extreme halophiles, a universal characteristic of halophilic bacteria. Herein, we report the production of halocin (SH10) by an extremely halophilic archeon Natrinema sp. BTSH10 isolated from salt pan of Kanyakumari, Tamilnadu, India and optimization of medium for enhanced production of halocin. It was found that the optimal conditions for maximal halocin production were 42 °C, pH 8.0, and 104 h of incubation at 200 rpm with 2% (V/V) inoculum concentration in Zobell’s medium containing 3 M NaCl, Galactose, beef extract, and calcium chloride as additional supplements. Results indicated scope for fermentation production of halocin for probable applications using halophilic archeon Natrinema sp. BTSH10.     

Feasibility of neonatal haemoglobin A1C as a biomarker for retinopathy of prematurity

Abstract

Introduction

Retinopathy of prematurity (ROP) is a potentially serious eye disorder affecting very preterm infants. Non-proliferative ROP (NP-ROP), also known as Early Stage ROP, is characterized by deficient retinal angiogenesis. Proliferative ROP (P-ROP), also known as Late Stage ROP, is characterized by pathologic angiogenesis. The use of neonatal haemoglobin A1C as a biomarker for ROP has not yet been evaluated.     

Insufficient (Sub-native) Helix Content in Soluble/Solid Aggregates of Recombinant and Engineered Forms of IL-2 Throws Light on How Aggregated IL-2 is Biologically Active

Interleukin 2 (IL-2) is an extremely aggregation-prone, all-alpha helical cytokine. In its receptor-bound state,?~72?% of the polypeptide chain adopts helical structure and there is no beta sheet content whatsoever. In the past, recombinant IL-2 has been formulated and used therapeutically in humans, following production in E. coli. Therapeutic IL-2 consists entirely of functionally-active soluble aggregates with?~30 subunits per aggregate particle. Side-effects attributed to aggregation resulted in discontinuation of usage over a decade ago. Structurally, and biochemically, activity in IL-2 aggregates can potentially be explained in one of two ways : (a) individual IL-2 chains exist in sterically-accessible, receptor binding-competent (native) structures, allowing aggregates to bind directly to IL-2 receptors (IL-2R); alternatively, (b) IL-2 chains dissociate from aggregates, become free to adopt native structure, and then bind to IL-2R. We produced native IL-2 and numerous engineered forms in E. coli with the objective of obtaining insights into these possibilities. Each IL-2 variant was subjected to size exclusion chromatography, circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR). All forms produced and studied (including those with native IL-2 sequences) turned out to aggregate and also display less than?~50?% helix content as well as significant beta sheet content. No conditions were found that obviate aggregation. Aggregated IL-2 is thus insufficiently native-like to bind to IL-2R. Activity in aggregates thus probably owes to adoption of receptor binding-competent structures by chains that have already dissociated from aggregates.     

Acid sphingomyelinase-dependent autophagic degradation of GPX4 is critical for the execution of ferroptosis

Ferroptosis is a type of regulated cell death characterized by ROS accumulation and devastating lipid peroxidation (LPO). The role of acid sphingomyelinase (ASM), a key enzyme in sphingolipid metabolism, in the induction of apoptosis has been studied; however, to date its role in ferroptosis is unclear. In this study, we report that ASM plays a hitherto unanticipated role in promoting ferroptosis. Mechanistically, Erastin (Era) treatment results in the activation of ASM and generation of ceramide, which are required for the Era-induced reactive oxygen species (ROS) generation and LPO. Inhibition of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) or removal of intracellular ROS, significantly reduced Era-induced ASM activation, suggesting that NADPH oxidase-derived ROS regulated ASM-initiated redox signaling in a positive feedback manner. Moreover, ASM-mediated activation of autophagy plays a critical role in ferroptosis inducers (FINs)-induced glutathione peroxidase 4 (GPX4) degradation and ferroptosis activation. Genetic or pharmacological inhibition of ASM diminishes Era-induced features of autophagy, GPX4 degradation, LPO, and subsequent ferroptosis. Importantly, genetic activation of ASM increases ferroptosis in cancer cells induced by various FINs. Collectively, these findings reveal that ASM plays a novel role in ferroptosis that could be exploited to improve pathological conditions that link to ferroptosis.Subject terms: Lipid peroxides, Cancer models, Macroautophagy, Lipid signalling