The cell cycle-regulated protein human GTSE-1 controls DNA damage-induced apoptosis by affecting p53 function

GTSE-1 (G2 and S phase-expressed-1) protein is specifically expressed during S and G2 phases of the cell cycle. It is mainly localized to the microtubules and when overexpressed delays the G2 to M transition. Here we report that human GTSE-1 (hGTSE-1) protein can negatively regulate p53 transactivation function, protein levels, and p53-dependent apoptosis. We identified a physical interaction between the C-terminal regulatory domain of p53 and the C-terminal region of hGTSE-1 that is necessary and sufficient to down-regulate p53 activity. Furthermore, we provide evidence that hGTSE-1 is able to control p53 function in a cell cycle-dependent fashion. hGTSE-1 knock-down by small interfering RNA resulted in a S/G2-specific increase of p53 levels as well as cell sensitization to DNA damage-induced apoptosis during these phases of the cell cycle. Altogether, this work suggests a physiological role of hGTSE-1 in apoptosis control after DNA damage during S and G2 phases through regulation of p53 function.     

Fibrotic enzymes modulate wound‐induced skin tumorigenesis

Fibroblasts are a major component of the microenvironment of most solid tumours. Recent research elucidated a large heterogeneity and plasticity of activated fibroblasts, indicating that their role in cancer initiation, growth and metastasis is complex and context‐dependent. Here, we performed genome‐wide expression analysis comparing fibroblasts in normal, inflammatory and tumour‐associated skin. Cancer‐associated fibroblasts (CAFs) exhibit a fibrotic gene signature in wound‐induced tumours, demonstrating persistent extracellular matrix (ECM) remodelling within these tumours. A top upregulated gene in mouse CAFs encodes for PRSS35, a protease capable of collagen remodelling. In human skin, we observed PRSS35 expression uniquely in the stroma of high‐grade squamous cell carcinomas. Ablation of PRSS35 in mouse models of wound‐ or chemically‐induced tumorigenesis resulted in aberrant collagen composition in the ECM and increased tumour incidence. Our results indicate that fibrotic enzymes expressed by CAFs can regulate squamous tumour initiation by remodelling the ECM.     

Three-dimensional folding and functional organization principles of the Drosophila genome

Chromosomes are the physical realization of genetic information and thus form the basis for its readout and propagation. Here we present a high-resolution chromosomal contact map derived from a modified genome-wide chromosome conformation capture approach applied to Drosophila embryonic nuclei. The data show that the entire genome is linearly partitioned into well-demarcated physical domains that overlap extensively with active and repressive epigenetic marks. Chromosomal contacts are hierarchically organized between domains. Global modeling of contact density and clustering of domains show that inactive domains are condensed and confined to their chromosomal territories, whereas active domains reach out of the territory to form remote intra- and interchromosomal contacts. Moreover, we systematically identify specific long-range intrachromosomal contacts between Polycomb-repressed domains. Together, these observations allow for quantitative prediction of the Drosophila chromosomal contact map, laying the foundation for detailed studies of chromosome structure and function in a genetically tractable system.     

Sex hormone levels in the brain of d-aspartate-treated rats

d-Aspartate (d-Asp) is an endogenous amino acid present in the central nervous system and endocrine glands of various animal taxa. d-Asp is implicated in neurotransmission, physiology of learning, and memory processes. In gonads, it plays a crucial role in sex hormone synthesis. We have investigated the effects of chronic (30 days d-Asp drinking solution) and acute (i.p. injection of 2 μmol/g bw d-Asp) treatments on sex steroid synthesis in rat brain. Furthermore, to verify the direct effect of d-Asp on neurosteroidogenic enzyme activities, brain homogenates were incubated with different substrates (cholesterol, progesterone, or testosterone) with or without the addition of d-Asp. Enzyme activities were measured by evaluating the in vitro conversion rate of (i) cholesterol to progesterone, testosterone, and 17β-estradiol, (ii) progesterone to testosterone and 17β-estradiol, (iii) testosterone to 17β-estradiol. We found that d-Asp oral administration produced an increase of approximately 40% in progesterone, 110% in testosterone, and 35% in 17β-estradiol. Similarly, the results of the acute experiment showed that at 30 min after d-Asp treatment, the progesterone, testosterone, and 17β-estradiol levels increased by 29–35%, and at 8 h they further increased by a 100% increment. In vitro experiments demonstrate that the addition of d-Asp to brain homogenate + substrate induces a significant increase in progesterone, testosterone and 17β-estradiol suggesting that the amino acid upregulates the local activity of steroidogenic enzymes.     

A new enzymatic route to the synthesis of 12-ketoursodeoxycholic acid

Summary Cholic acid (3,7,12-trihydroxy-5-cholanoic acid) was completely and selectively transformed into 12-ketoursodeoxycholic acid (3,7-dihydroxy-12-oxo-5-cholanoic acid) by means of two consecutive enzymatic steps catalyzed, the first, by 7- and 12-hydroxysteroid dehydrogenase and, the second, by 7-hydroxysteroid dehydrogenase. Coenzyme regeneration was carried out with -ketoglutarate-glutamate dehydrogenase and glucose-glucose dehydrogenase, respectively.     

Effects on interfacial properties and cell adhesion of surface modification by pectic hairy regions

Polystyrene Petri dishes, aminated by a plasma deposition process, were surface modified by the covalent linking of two different enzymatically modified hairy regions (HRs) from pectin containing, for example, rhamnogalacturonan-I and xylogalacturonan structural elements. The two polysaccharide preparations share the same structural elements of apple pectin, but the relative amounts and lengths of the neutral side chains present differ. Surface analysis by X-ray photoelectron spectroscopy, contact angle measurement, and atomic force microscope (AFM) force-separation curves was used to characterize the effects on surface chemistry and interfacial forces of the surface modification process. Cell adhesion experiments using continuous L-929 fibroblasts and primary aortic smooth muscle cells were performed to evaluate the effect of the polysaccharide nature on cell adhesion. Results show that immobilization of the HR affects the interfacial field of forces and the cell behavior: "equilibrium" contact angles, obtained by a recently introduced vibrational approach, decrease after HR immobilization reaching a value close to 20 degrees . AFM force-separation curves show a more extended (or softer) interface in the case of the HR bearing longer side chains. Accordingly, depending on the HR preparation, cells shifted from spread morphology and adhesion behavior quantitatively comparable to that observed on conventional tissue culture polystyrene to rounded morphology and significantly lower adhesion. These data show that engineering of plant pectins can be a valuable tool to prepare novel and finely tuned polysaccharides having different chemico-physical and biological properties, to be used in the surface modification of medical devices and materials.     

Copepods in spring annual sea ice at Terra Nova Bay (Ross Sea,Antarctica)

The aim of this study was to investigate patterns of abundance, distribution, temporal changes and species composition of the dominant ice-associated copepods in the spring annual pack ice, platelet ice and water column at Terra Nova Bay, Ross Sea, during late spring 1997. Ice cores were drilled for temporal and spatial scales. Stephos longipes and Harpacticus furcifer dominated the sea ice meiofauna in terms of numbers in the lower few centimeters of the bottom ice associated with high chlorophyll a and phaeopigment levels. Nauplii dominated the S. longipes population (91.6%) and occurred in extremely high concentrations. In contrast, copepodids were the dominant stages in H. furcifer. How H. furcifer carries out its entire life cycle and how it differs from ecologically similar species such as Drescheriella glacialis should be examined in more detail.     

MicroRNAs as regulators of cell death mechanisms in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting upper and lower motor neurons (MNs), resulting in paralysis and precocious death from respiratory failure. Although the causes of ALS are incompletely understood, the role of alterations in RNA metabolism seems central. MicroRNAs (miRNAs) are noncoding RNAs implicated in the regulation of gene expression of many relevant physiological processes, including cell death. The recent model of programmed cell death (PCD) encompasses different mechanisms, from apoptosis to regulated necrosis (RN), in particular necroptosis. Both apoptosis and necroptosis play a significant role in the progressive death of MNs in ALS. In this review, we present key research related to miRNAs that modulate apoptosis and RN pathways in ALS. We also discuss whether these miRNAs represent potential targets for therapeutic development in patients.