Secretory carrier membrane proteins

Secretory carrier membrane proteins (SCAMPs) are a family of integral membrane proteins that play roles in mediating exocytosis in animal cells. However, relatively little is known about the subcellular localization, trafficking, and function of SCAMPs in plants. Several recent studies in plant cells indicate that plant SCAMPs share many similarities with their mammalian homologs although there are differences. In this review, we will first summarize and compare animal and plant SCAMPs in terms of their subcellular localization, trafficking, and possible functions. We will then present a phylogenetic analysis of plant and animal SCAMPs. Finally, we will present expression analysis on selective Arabidopsis SCAMPs in the hope of pointing to directions for functional characterization of plant SCAMPs in the future.     

ELF3 recruitment to the PRR9 promoter requires other Evening Complex members in the Arabidopsis circadian clock

Biological timekeeping is essential for proper growth and development. Organisms such as the model plant Arabidopsis use the circadian clock to coordinate biological processes with the environment so that changes in conditions are anticipated and processes favorably phased. Despite the identification of numerous clock genes, knowledge of their molecular connectivity and influence on output programs remains limited. We recently showed LUX encodes a sequence-specific DNA-binding protein that directly regulates expression of the morning clock gene PRR9. We also showed that LUX interacts with the evening-phased proteins ELF3 and ELF4 to form a complex called the Evening Complex (EC). The EC binds the PIF4 and PIF5 promoters to control hypocotyl growth as a clock output. Here we provide evidence that LUX also recruits ELF3 to the PRR9 promoter. As with the PIF4 and PIF5 promoters, both LUX and its close homolog NOX are required for recruitment. Hence the entire EC likely functions together as part of the core clock oscillator to optimize plant fitness.     

Molecular orientation of tropoelastin is determined by surface hydrophobicity

Tropoelastin is the precursor of the extracellular protein elastin and is utilized in tissue engineering and implant technology by adapting the interface presented by surface-bound tropoelastin. The preferred orientation of the surface bound protein is relevant to biointerface interactions, as the C-terminus of tropoelastin is known to be a binding target for cells. Using recombinant human tropoelastin we monitored the binding of tropoelastin on hydrophilic silica and on silica made hydrophobic by depositing a self-assembled monolayer of octadecyl trichlorosilane. The layered organization of deposited tropoelastin was probed using neutron and X-ray reflectometry under aqueous and dried conditions. In a wet environment, tropoelastin retained a solution-like structure when adsorbed on silica but adopted a brush-like structure when on hydrophobized silica. The orientation of the surface-bound tropoelastin was investigated using cell binding assays and it was found that the C-terminus of tropoelastin faced the bulk solvent when bound to the hydrophobic surface, but a mixture of orientations was adopted when tropoelastin was bound to the hydrophilic surface. Drying the tropoelastin-coated surfaces irreversibly altered these protein structures for both hydrophilic and hydrophobic surfaces.     

Influence of Formulation and Processing Variables on Properties of Itraconazole Nanoparticles Made by Advanced Evaporative Precipitation into Aqueous Solution

Nanoparticles, of the poorly water-soluble drug, itraconazole (ITZ), were produced by the Advanced Evaporative Precipitation into Aqueous Solution process (Advanced EPAS). This process combines emulsion templating and EPAS processing to provide improved control over the size distribution of precipitated particles. Specifically, oil-in-water emulsions containing the drug and suitable stabilizers are sprayed into a heated aqueous solution to induce precipitation of the drug in form of nanoparticles. The influence of processing parameters (temperature and volume of the heated aqueous solution; type of nozzle) and formulation aspects (stabilizer concentrations; total solid concentrations) on the size of suspended ITZ particles, as determined by laser diffraction, was investigated. Furthermore, freeze-dried ITZ nanoparticles were evaluated regarding their morphology, crystallinity, redispersibility, and dissolution behavior. Results indicate that a robust precipitation process was developed such that size distribution of dispersed nanoparticles was shown to be largely independent across the different processing and formulation parameters. Freeze-drying of colloidal dispersions resulted in micron-sized agglomerates composed of spherical, sub-300-nm particles characterized by reduced crystallinity and high ITZ potencies of up to 94% (w/w). The use of sucrose prevented particle agglomeration and resulted in powders that were readily reconstituted and reached high and sustained supersaturation levels upon dissolution in aqueous media.     

Inhibition of Eg5 acts synergistically with checkpoint abrogation in promoting mitotic catastrophe

The G(2) DNA damage checkpoint is activated by genotoxic agents and is particularly important for cancer therapies. Overriding the checkpoint can trigger precocious entry into mitosis, causing cells to undergo mitotic catastrophe. But some checkpoint-abrogated cells can remain viable and progress into G(1) phase, which may contribute to further genome instability. Our previous studies reveal that the effectiveness of the spindle assembly checkpoint and the duration of mitosis are pivotal determinants of mitotic catastrophe after checkpoint abrogation. In this study, we tested the hypothesis whether mitotic catastrophe could be enhanced by combining genotoxic stress, checkpoint abrogation, and the inhibition of the mitotic kinesin protein Eg5. We found that mitotic catastrophe induced by ionizing radiation and a CHK1 inhibitor (UCN-01) was exacerbated after Eg5 was inhibited with either siRNAs or monastrol. The combination of DNA damage, UCN-01, and monastrol sensitized cancer cells that were normally resistant to checkpoint abrogation. Importantly, a relatively low concentration of monastrol, alone not sufficient in causing mitotic arrest, was already effective in promoting mitotic catastrophe. These experiments suggest that it is possible to use sublethal concentrations of Eg5 inhibitors in combination with G(2) DNA damage checkpoint abrogation as an effective therapeutic approach.     

Identification of a Novel Calotropis procera Protein That Can Suppress Tumor Growth in Breast Cancer through the Suppression of NF-κB Pathway

Breast cancer is the most common cancer among women. To date, improvements in hormonal and cytotoxic therapies have not yet led to a sustained remission or cure. In the present study, we investigated the in vitro and in vivo antitumor activities of a novel Calotropis procera protein (CP-P) isolated from root bark. CP-P protein inhibited the proliferation and induced apoptosis of breast cancer cells through the suppression of nuclear factor kappaB (NF-kB) activation. CP-P, when administered individually or in combination with cyclophosphamide (CYC, 0.2 mg/kg) to rats with 7, 12-dimethyl benz(a)anthracene (DMBA)-induced breast cancer decreased tumor volume significantly without affecting the body weight. To elucidate the anticancer mechanism of CP-P, antioxidant activities such as superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) and non-enzymatic antioxidant - reduced glutathione (GSH), vitamin E and C generation in the breast were analyzed by various assays. SOD, CAT, GST, GSH, vitamin E and C levels were high in combination-treated groups (CP-P+CYC) versus the CYC alone-treated groups. Also, the combination was more effective in down-regulating the expression of NF-kB-regulated gene products (cyclin D1 and Bcl-2) in breast tumor tissues. Our findings indicate that CP-P possesses significant antitumor activity comparable to a commonly used anticancer drug, cyclophosphamide, and may form the basis of a novel therapy for breast cancer.     

Association between anaemia, iron deficiency anaemia, neglected parasitic infections and socioeconomic factors in rural children of West Malaysia

Background

Given that micronutrient deficiency, neglected intestinal parasitic infections (IPIs) and poor socioeconomic status are closely linked, we conducted a cross-sectional study to assess the relationship between IPIs and nutritional status of children living in remote and rural areas in West Malaysia.

Methods/Findings

A total of 550 children participated, comprising 520 (94.5%) school children aged 7 to 12 years old, 30 (5.5%) young children aged 1 to 6 years old, 254 (46.2%) boys and 296 (53.8%) girls. Of the 550 children, 26.2% were anaemic, 54.9% iron deficient and 16.9% had iron deficiency anaemia (IDA). The overall prevalence of helminths was 76.5% comprising Trichuris trichiura (71.5%), Ascaris lumbricoides (41.6%) and hookworm infection (13.5%). It was observed that iron deficiency was significantly higher in girls (p = 0.032) compared to boys. Univariate analysis demonstrated that low level of mother''s education (OR = 2.52; 95% CI = 1.38–4.60; p = 0.002), non working parents (OR = 2.18; 95% CI = 2.06–2.31; p = 0.013), low household income (OR = 2.02; 95% CI = 1.14–3.59; p = 0.015), T. trichiura (OR = 2.15; 95% CI = 1.21–3.81; p = 0.008) and A. lumbricoides infections (OR = 1.63; 95% CI = 1.04–2.55; p = 0.032) were significantly associated with the high prevalence of IDA. Multivariate analysis confirmed that low level of mother''s education (OR = 1.48; 95 CI% = 1.33–2.58; p<0.001) was a significant predictor for IDA in these children.

Conclusion

It is crucial that a comprehensive primary health care programme for these communities that includes periodic de-worming, nutrition supplement, improved household economy, education, sanitation status and personal hygiene are taken into consideration to improve the nutritional status of these children.     

Distinct role of matrix metalloproteinase-3 in kidney injury molecule-1 shedding by kidney proximal tubular epithelial cells

Tubulointerstitial injury is a common pathway in progressive renal impairment and human proximal tubular epithelial cells (PTEC) play a crucial role in this process. Kidney injury molecule-1 (KIM-1) has received increasing attention due to its potential utility as the therapeutic target and biomarker for kidney injury. This study aims to explore the underlying mechanism regulating the release of KIM-1. Cultured primary human PTEC expressed and released KIM-1 from the apical surface through an ectodomain shedding process mediated by matrix metalloproteinase (MMP), independent of gene expression and protein synthesis. The constitutive KIM-1 shedding by PTEC was enhanced in a dose- and time-dependent manner by human serum albumin (HSA) or tumor necrosis factor-α (TNF-α), two important physiological stimuli found during kidney injury. Data from PCR array screening of MMPs gene expression in PTEC following activation by HSA or TNF-α, and from blocking experiments using either synthetic MMP inhibitors or MMP gene knockdown by siRNA, revealed that the constitutive and accelerated shedding of KIM-1 in cultured PTEC was mediated by MMP-3. Furthermore, the up-regulation of MMP-3 and KIM-1 release by PTEC was associated with generation of reactive oxygen species. In a mouse model of acute kidney injury induced by ischemia and reperfusion, increased expression of MMP-3 and KIM-1 as well as their co-localization were observed in kidney from ischemic but not in sham-operated mice. Taken together, these in vitro and in vivo evidences suggest that MMP-3 plays an inductive role in KIM-1 shedding by PTEC.