Plasma Membrane Repair Is Regulated Extracellularly by Proteases Released from Lysosomes

Eukaryotic cells rapidly repair wounds on their plasma membrane. Resealing is Ca^2+-dependent, and involves exocytosis of lysosomes followed by massive endocytosis. Extracellular activity of the lysosomal enzyme acid sphingomyelinase was previously shown to promote endocytosis and wound removal. However, whether lysosomal proteases released during cell injury participate in resealing is unknown. Here we show that lysosomal proteases regulate plasma membrane repair. Extracellular proteolysis is detected shortly after cell wounding, and inhibition of this process blocks repair. Conversely, surface protein degradation facilitates plasma membrane resealing. The abundant lysosomal cysteine proteases cathepsin B and L, known to proteolytically remodel the extracellular matrix, are rapidly released upon cell injury and are required for efficient plasma membrane repair. In contrast, inhibition of aspartyl proteases or RNAi-mediated silencing of the lysosomal aspartyl protease cathepsin D enhances resealing, an effect associated with the accumulation of active acid sphingomyelinase on the cell surface. Thus, secreted lysosomal cysteine proteases may promote repair by facilitating membrane access of lysosomal acid sphingomyelinase, which promotes wound removal and is subsequently downregulated extracellularly by a process involving cathepsin D.     

Conditional restoration and inactivation of Rbm47 reveal its tissue‐context requirement for viability and growth

Rbm47 encodes a RNA binding protein that is necessary for Cytidine to Uridine RNA editing. Rbm47^gt/gt mutant mice that harbor inactivated Rbm47 display poor viability. Here it was determined that the loss of Rbm47^gt/gt offspring is due to embryonic lethality at mid‐gestation. It was further showed that growth of the surviving Rbm47^gt/gt mutants is impaired. Rbm47 is expressed in both the visceral endoderm and the definitive endoderm. Using the utility of the switchable FlEx gene‐trap cassette and the activity of Cre and FLP recombinases to generate mice that conditionally inactivate and restore Rbm47 function in tissue‐specific manner, it was demonstrated that Rbm47 function is required in the embryo proper, and not the visceral endoderm, for viability and growth. genesis 54:115–122, 2016. © 2016 Wiley Periodicals, Inc.     

Anticancer activity of paroxetine in human colon cancer cells: Involvement of MET and ERBB3

The concept of drug repositioning has recently received considerable attention in the field of oncology. In the present study, we propose that paroxetine can be used as a potent anticancer drug. Paroxetine, one of the selective serotonin reuptake inhibitors (SSRIs), has been widely prescribed for the treatment of depression and anxiety disorders. Recently, SSRIs have been reported to have anticancer activity in various types of cancer cells; however, the underlying mechanisms of their action are not yet known. In this study, we investigated the potential anticancer effect of paroxetine in human colorectal cancer cells, HCT116 and HT‐29. Treatment with paroxetine reduced cell viability, which was associated with marked increase in apoptosis, in both the cell lines. Also, paroxetine effectively inhibited colony formation and 3D spheroid formation. We speculated that the mode of action of paroxetine might be through the inhibition of two major receptor tyrosine kinases – MET and ERBB3 – leading to the suppression of AKT, ERK and p38 activation and induction of JNK and caspase‐3 pathways. Moreover, in vivo experiments revealed that treatment of athymic nude mice bearing HT‐29 cells with paroxetine remarkably suppressed tumour growth. In conclusion, paroxetine is a potential therapeutic option for patients with colorectal cancer.     

Synthesis of deoxy and methoxy analogs of octyl alpha-D-mannopyranosyl-(1-->6)-alpha-D-mannopyranoside as probes for mycobacterial lipoarabinomannan biosynthesis

A panel of analogs of the disaccharide alpha-D-Manp-(1-->6)-alpha-D-Manp-OOctyl, a known acceptor substrate for a polyprenol monophosphomannose-dependent alpha-(1-->6)-mannosyltransferase involved in the assembly of the alpha-(1-->6)-linked mannan core of mycobacterial lipoarabinomannan, has been synthesized. Described are synthetic routes to the target deoxy and methoxy analogs in which one of the hydroxyl groups of the parent disaccharide has been modified. All glycosylation reactions involved the use of octyl glycoside acceptors and thioglycoside donors using iodonium-ion activation, and the stereochemistry of the mannopyranoside bond formed was established by measurement of the 1J(C-1,H-1). Depending on the target, the key methylation or deoxygenation reactions were carried out on either mono- or disaccharide substrates. This series of analogs will be useful for probing the substrate specificity of the enzyme, in particular, its steric and hydrogen-bonding requirements.     

WHY DO SOME SIBLINGS ATTACK EACH OTHER? COMPARATIVE ANALYSIS OF AGGRESSION IN AVIAN BROODS

In many parentally fed species, siblings compete for food not only by begging and scrambling, but also by violently attacking each other. This aggressive competition has mostly been studied in birds, where it is often combined with dominance subordination, aggressive intimidation, and siblicide. Previous experimental and theoretical studies proposed several life-history, morphological, and behavioral variables that may facilitate the evolution of broodmate aggression, and explain its taxonomic distribution. Here we apply phylogenetic comparative analyses for the first time to test the influence of five hypothesized facilitators of the evolution of broodmate aggression, analyzing 69 species in seven avian families using two quantitative measures of aggression: incidence and intensity. We show that incidence and intensity of aggression increase with long nestling periods and indirect feeding, and small brood size is associated with intense aggression. Large food parcels were not correlated with either the incidence or intensity of aggression. Our study suggests that indirect feeding, long nestling periods, and small broods, possibly in combination with other factors, have tended to favor the evolution of aggressive broodmate competition.     

Genetic variation,demographic history and phylogeography of tire track eel,Mastacembelus favus (Synbranchiformes: Mastacembelidae) in Southeast Asia

The complex climatic and geological history of Southeast Asia has been hypothesised to determine the most important aspects of the current phylogeographical structure and distribution of living organisms throughout the region. To test existing hypotheses, the genetic structure of the tire track eel, Mastacembelus favus, was investigated using 823 bp of mitochondrial DNA cytochrome b from 469 individuals from 51 localities encompassing its native range. The results classified all haplotypes into two major lineages, Lineage 1, which was further divided into Lineages 1a (lower Mekong, eastern Gulf of Thailand and Malay—Thai Peninsula), 1b (Banpakong River), 1c (Chao Phraya, Gulf of Thailand and Malay—Thai Peninsula) and 1d (Khlang Yai River), and Lineage 2, the upper reaches of the lower Mekong and the middle Mekong. Strong genetic discontinuities dated approximately 5 MYA were discovered in the Mekong with limited geographical overlap, suggesting a historically dissected drainage between two sections and species colonisation via different routes. The widespread Lineage 1 showed a strong signature of population expansion during the Pleistocene climate oscillation. Haplotype characteristics in the Malay—Thai Peninsula are hypothesised to result from postglacial dispersal from the Mekong and Chao Phraya through an extended Pleistocene drainage network.

     

Ecology,conservation, and phylogenetic position of the Madagascar Jacana Actophilornis albinucha

The Madagascar Jacana Actophilornis albinucha (Jacanidae) is an endemic shorebird found in the threatened wetlands of western Madagascar. This species is presumed to exhibit classical polyandry; however, few data are available to support that assumption. More generally, a lack of basic understanding of this species hinders conservation efforts. We conducted the most extensive study of the Madagascar Jacana to date, and report on its: 1) distribution, population size and density; 2) degree of sexual size dimorphism; and 3) phylogenetic position. The surveys were conducted at 54 lakes, between January and October in 2016. Madagascar Jacana were found at 22 lakes, and within these were distributed at a mean density of 3.5 ± 0.74 [SE] individuals per hectare of surveyed habitat. We estimate the global population size to be between 975 and 2 064 individuals, and habitat destruction appears to be the main threat to the species. Females were significantly larger than males, consistent with reports for other Jacanidae species. Using a mitochondrial DNA fragment, we expanded the Jacanidae genetic phylogeny, and confirmed that Madagascar Jacana is the sister species to the African Jacana Actophilornis africanus. Further studies are urgently needed to thoroughly re-assess the threat status and population trend of the Madagascar Jacana.