Prevention and treatment of respiratory syncytial virus bronchiolitis and postbronchiolitic wheezing

Growth factors mediate tissue interactions and regulate a variety of cellular functions that are critical for normal lung development and homeostasis. Besides their involvement in lung pattern formation, growth and cell differentiation during organogenesis, these factors have been also implicated in modulating injury-repair responses of the adult lung. Altered expression of growth factors, such as transforming growth factor β1, vascular endothelial growth factor and epidermal growth factor, and/or their receptors, has been found in a number of pathological lung conditions. In this paper, we discuss the dual role of these molecules in mediating beneficial feedback responses or responses that can further damage lung integrity; we shall also discuss the basis for their prospective use as therapeutic agents.     

Insights into the interaction of high potency inhibitor IRC‐083864 with phosphatase CDC25

CDC25 phosphatases play a crucial role in cell cycle regulation. They have been found to be over‐expressed in various human tumours and to be valuable targets for cancer treatment. Here, we report the first model of binding of the most potent CDC25 inhibitor to date, the bis‐quinone IRC‐083864, into CDC25B obtained by combining molecular modeling and NMR studies. Our study provides new insights into key interactions of the catalytic site inhibitor and CDC25B in the absence of any available experimental structure of CDC25 with a bound catalytic site inhibitor. The docking model reveals that IRC‐083864 occupies both the active site and the inhibitor binding pocket of the CDC25B catalytic domain. NMR saturation transfer difference and WaterLOGSY data indicate the binding zones of the inhibitor and support the docking model. Probing interactions of analogues of the two quinone units of IRC‐083864 with CDC25B demonstrate that IRC‐083864 competes with each monomer. Proteins 2017; 85:593–601. © 2016 Wiley Periodicals, Inc.     

Kalign – an accurate and fast multiple sequence alignment algorithm

Background  

The alignment of multiple protein sequences is a fundamental step in the analysis of biological data. It has traditionally been applied to analyzing protein families for conserved motifs, phylogeny, structural properties, and to improve sensitivity in homology searching. The availability of complete genome sequences has increased the demands on multiple sequence alignment (MSA) programs. Current MSA methods suffer from being either too inaccurate or too computationally expensive to be applied effectively in large-scale comparative genomics.     

Potential roles of the nucleotide exchange factor ECT2 and Cdc42 GTPase in spindle assembly in Xenopus egg cell-free extracts

The ECT2 protooncogene encodes a guanine nucleotide exchange factor for the Rho family of small GTPases. ECT2 contains motifs of cell cycle regulators at its N-terminal domain. We previously showed that ECT2 plays a critical role in cytokinesis. Here, we report a potential role of XECT2, the Xenopus homologue of the human ECT2, in spindle assembly in cell-free Xenopus egg extracts. Cloned XECT2 cDNA encodes a 100 kDa protein closely related to human ECT2. XECT2 is specifically phosphorylated in M phase extracts. Affinity-purified anti-XECT2 antibody strongly inhibited mitosis in Xenopus cell-free extracts. Instead of bipolar spindles, where chromosomes are aligned at the metaphase plane in control extracts, the addition of anti-XECT2 resulted in the appearance of abnormal spindles including monopolar and multipolar spindles as well as bipolar spindles with misaligned chromosomes. In these in vitro synthesized spindle structures, XECT2 was found to tightly associate with mitotic spindles. The N-terminal half of XECT2 lacking the catalytic domain also strongly inhibited spindle assembly in vitro, resulting in the formation of mitotic spindles with a low density. Among the representative Rho GTPases, a dominant-negative form of Cdc42 strongly inhibited spindle assembly in vitro. These results suggest that the Rho family GTPase Cdc42 and its exchange factor XECT2 are critical regulators of spindle assembly in Xenopus egg extracts.     

Distinct in vivo dynamics of vertebrate SUMO paralogues

There are three mammalian SUMO paralogues: SUMO-1 is approximately 45% identical to SUMO-2 and SUMO-3, which are 96% identical to each other. It is currently unclear whether SUMO-1, -2, and -3 function in ways that are unique, redundant, or antagonistic. To address this question, we examined the dynamics of individual SUMO paralogues by using cell lines that stably express each of the mammalian SUMO proteins fused to the yellow fluorescent protein (YFP). Whereas SUMO-2 and -3 showed very similar distributions throughout the nucleoplasm, SUMO-1 was uniquely distributed to the nuclear envelope and to the nucleolus. Photobleaching experiments revealed that SUMO-1 dynamics was much slower than SUMO-2 and -3 dynamics. Additionally, the mobility of SUMO paralogues differed between subnuclear structures. Finally, the timing and distributions were dissimilar between paralogues as cells exited from mitosis. SUMO-1 was recruited to nuclear membrane as nuclear envelopes reformed in late anaphase, and accumulated rapidly into the nucleus. SUMO-2 and SUMO-3 localized to chromosome earlier and accumulated gradually during telophase. Together, these findings demonstrate that mammalian SUMO-1 shows patterns of utilization that are clearly discrete from the patterns of SUMO-2 and -3 throughout the cell cycle, arguing that it is functionally distinct and specifically regulated in vivo.     

Interactions between hypoxia and hypercapnic acidosis on calcium signaling in carotid body type I cells

The effects of hypercapnic acidosis and hypoxia on intracellular Ca(2+) concentration ([Ca(2+)](i)) were determined with Indo 1 in enzymatically isolated single type I cells from neonatal rat carotid bodies. Type I cells responded to graded hypoxic stimuli with graded [Ca(2+)](i) rises. The percentage of cells responding was also dependent on the severity of the hypoxic stimulus. Raising CO(2) from 5 to 10 or 20% elicited a significant increase in [Ca(2+)](i) in the same cells as those that responded to hypoxia. Thus both stimuli can be sensed by each individual cell. When combinations of hypoxic and acidic stimuli were given simultaneously, the responses were invariably greater than the response to either stimulus given alone. Indeed, in most cases, the response to hypercapnia was slightly potentiated by hypoxia. These data provide the first evidence that the classic synergy between hypoxic and hypercapnic stimuli observed in the intact carotid body may, in part, be an inherent property of the type I cell.