Gossypol Induces Death Receptor-5 through Activation of the ROS-ERK-CHOP Pathway and Sensitizes Colon Cancer Cells to TRAIL

Development of resistance to TRAIL, an apoptosis-inducing cytokine, is one of the major problems in its development for cancer treatment. Thus, pharmacological agents that are safe and can sensitize the tumor cells to TRAIL are urgently needed. We investigated whether gossypol, a BH3 mimetic that is currently in the clinic, can potentiate TRAIL-induced apoptosis. Intracellular esterase activity, sub-G₁ cell cycle arrest, and caspase-8, -9, and -3 activity assays revealed that gossypol potentiated TRAIL-induced apoptosis in human colon cancer cells. Gossypol also down-regulated cell survival proteins (Bcl-x_L, Bcl-2, survivin, XIAP, and cFLIP) and dramatically up-regulated TRAIL death receptor (DR)-5 expression but had no effect on DR4 and decoy receptors. Gossypol-induced receptor induction was not cell type-specific, as DR5 induction was observed in other cell types. Deletion of DR5 by siRNA significantly reduced the apoptosis induced by TRAIL and gossypol. Gossypol induction of the death receptor required the induction of CHOP, and thus, gene silencing of CHOP abolished gossypol-induced DR5 expression and associated potentiation of apoptosis. ERK1/2 (but not p38 MAPK or JNK) activation was also required for gossypol-induced TRAIL receptor induction; gene silencing of ERK abolished both DR5 induction and potentiation of apoptosis by TRAIL. We also found that reactive oxygen species produced by gossypol treatment was critical for TRAIL receptor induction and apoptosis potentiation. Overall, our results show that gossypol enhances TRAIL-induced apoptosis through the down-regulation of cell survival proteins and the up-regulation of TRAIL death receptors through the ROS-ERK-CHOP-DR5 pathway.     

Large-scale analysis of phosphorylation site occupancy in eukaryotic proteins

Many recent high throughput technologies have enabled large-scale discoveries of new phosphorylation sites and phosphoproteins. Although they have provided a number of insights into protein phosphorylation and the related processes, an inclusive analysis on the nature of phosphorylated sites in proteins is currently lacking. We have therefore analyzed the occurrence and occupancy of phosphorylated sites (~ 100,281) in a large set of eukaryotic proteins (~ 22,995). Phosphorylation probability was found to be much higher in both the termini of protein sequences and this is much pronounced in transmembrane proteins. A large proportion (51.3%) of occupied sites had a nearby phosphorylation within a distance of 10 amino acids; however, this proportion is very high compared to the expected one (16.9%). The distribution of phosphorylated sites in proteins showed a strong deviation from the expected maximum randomness. An analysis of phosphorylation motifs indicated that just 40 motifs and a much lower number of associated kinases might account for nearly 50% of the known phosphorylations in eukaryotic proteins. Our results provide a broad picture of the phosphorylation sites in eukaryotic proteins.     

Spatial Niche Partitioning in Sub-Tropical Solitary Ungulates: Four-Horned Antelope and Barking Deer in Nepal

Differential resource use allows a diversity of species to co-exist in a particular area by specializing in individual ecological niches. Four-horned antelope Tetracerus quadricornis is endemic to the Indian subcontinent and has a restricted distribution in Nepal and India; however, the barking deer Muntiacus vaginalis is relatively common throughout its wide distribution range. We wanted a better understanding of their habitats and how these two similarly sized solitary ungulates manage to coexist in lowland Nepal. We used fecal pellet belt transect surveys in the Babai valley, Bardia National Park to study the habitat associations of both species. We found empirical evidence that four-horned antelope prefer hill sal forest and deciduous hill forest at higher elevations, whereas barking deer preferred riverine and sal forest in lower elevations. We found a clear niche differentiation of four-horned antelope and barking deer that made the coexistence of these similarly sized solitary ungulates possible. Hence, resource partitioning is the key to coexistence of these solitary ungulates, and the fine-grained habitat mosaic of different forest types in the study landscape appears to be the underlying feature. Therefore, maintaining the habitat mosaic and preserving valuable hill sal and deciduous hill forests will facilitate the coexistence of herbivores in sub-tropical regions.     

Disease Specific Productivity of American Cancer Hospitals

Context

Research-oriented cancer hospitals in the United States treat and study patients with a range of diseases. Measures of disease specific research productivity, and comparison to overall productivity, are currently lacking.

Hypothesis

Different institutions are specialized in research of particular diseases.

Objective

To report disease specific productivity of American cancer hospitals, and propose a summary measure.

Method

We conducted a retrospective observational survey of the 50 highest ranked cancer hospitals in the 2013 US News and World Report rankings. We performed an automated search of PubMed and Clinicaltrials.gov for published reports and registrations of clinical trials (respectively) addressing specific cancers between 2008 and 2013. We calculated the summed impact factor for the publications. We generated a summary measure of productivity based on the number of Phase II clinical trials registered and the impact factor of Phase II clinical trials published for each institution and disease pair. We generated rankings based on this summary measure.

Results

We identified 6076 registered trials and 6516 published trials with a combined impact factor of 44280.4, involving 32 different diseases over the 50 institutions. Using a summary measure based on registered and published clinical trails, we ranked institutions in specific diseases. As expected, different institutions were highly ranked in disease-specific productivity for different diseases. 43 institutions appeared in the top 10 ranks for at least 1 disease (vs 10 in the overall list), while 6 different institutions were ranked number 1 in at least 1 disease (vs 1 in the overall list).

Conclusion

Research productivity varies considerably among the sample. Overall cancer productivity conceals great variation between diseases. Disease specific rankings identify sites of high academic productivity, which may be of interest to physicians, patients and researchers.     

In vitro hybridization in an incompatible cross Nicotiana glutinosa X Nicotiana megalosiphon

Summary Using conventional techniques interspecific hybridization between N. glutinosa (2n=24) and N. megalosiphon (2n=40) results in failure while the reciprocal is successful. Attempts were made here to obtain an F₁ hybrid of N. glutinosa X N. megalosiphon by embryo rescue. These reciprocal hybrids resembled each other in their phenotypic and chromosomal behaviour, i.e. there is broad spectrum of phenotypic variation coupled to chromosomal range from 2n-28 to 32. This may be due to the functional disharmony between chromosome sets of two unrelated species resulting in the elimination of chromosomes.     

Relationship Between [3H]Mazindol Binding to Dopamine Uptake Sites and [3H]Dopamine Uptake in Rat Striatum During Aging

Certain drugs exhibit a remarkable correlation between their ability to inhibit synaptosomal uptake of dopamine and the binding of [3H]mazindol to striatal membranes. To investigate the role of mazindol binding sites in the dopamine uptake process and the fate of these sites (labeling dopaminergic neurons) during aging, we have examined the properties of mazindol binding and dopamine uptake in individual young and old rats. There was a 48% decrease (p = 0.0001) in the Bmax of mazindol binding and a 23% decrease (p = 0.0166) in the Vmax of dopamine uptake with no apparent change in their affinities with age. Regression analysis of the relationship between Bmax and Vmax exhibited a significant correlation in old (p = 0.0156) but not young rats (p = 0.1398). These data suggest that the number of mazindol binding sites decreases with age and that the number of sites on the dopamine transporter complex far exceeds the number required to elicit maximal dopamine uptake.     

Preparation of galactans from <Emphasis Type=Italic>Gracilaria debilis</Emphasis> and <Emphasis Type=Italic>Gracilaria salicornia</Emphasis> (Gracilariales,Rhodophyta) of Indian waters

Superior quality non-methylated and low-sulphated galactans were extracted from two Indian agarophytes namely Gracilaria debilis and G. salicornia growing naturally along the west coast of India, using an eco-friendly method developed in our laboratory. The galactans were characterised by FT-IR, ¹³C NMR, GC-MS, ICP, GPC and rheological measurements. G. debilis produced exclusively non-methylated galactan exhibiting the greatest gel strength of 650±25 g cm⁻² and lowest sulphate of 0.21±0.06%. On the contrary, G. salicornia polysaccharide was composed of non-methylated galactose (major) and mannose (minor), having gel strength of 510±25 g cm⁻² and sulphate of 0.45±0.06%. Very low heavy metal contents were determined in both the galactan samples, which may thus be potentially useful in food and biological applications.