Full Length Bid is sufficient to induce apoptosis of cultured rat hippocampal neurons

Background  

Bcl-2 homology domain (BH) 3-only proteins are pro-apoptotic proteins of the Bcl-2 family that couple stress signals to the mitochondrial cell death pathways. The BH3-only protein Bid can be activated in response to death receptor activation via caspase 8-mediated cleavage into a truncated protein (tBid), which subsequently translocates to mitochondria and induces the release of cytochrome-C. Using a single-cell imaging approach of Bid cleavage and translocation during apoptosis, we have recently demonstrated that, in contrast to death receptor-induced apoptosis, caspase-independent excitotoxic apoptosis involves a translocation of full length Bid (FL-Bid) from the cytosol to mitochondria. We induced a delayed excitotoxic cell death in cultured rat hippocampal neurons by a 5-min exposure to the glutamate receptor agonist N-methyl-D-aspartate (NMDA; 300 μM).     

Paracrine control of tissue regeneration and cell proliferation by Caspase-3

Executioner caspases such as Caspase-3 and Caspase-7 have long been recognised as the key proteases involved in cell demolition during apoptosis. Caspase activation also modulates signal transduction inside cells, through activation or inactivation of kinases, phosphatases and other signalling molecules. Interestingly, a series of recent studies have demonstrated that caspase activation may also influence signal transduction and gene expression changes in neighbouring cells that themselves did not activate caspases. This review describes the physiological relevance of paracrine Caspase-3 signalling for developmental processes, tissue homeostasis and tissue regeneration, and discusses the role of soluble factors and microparticles in mediating these paracrine activities. While non-cell autonomous control of tissue regeneration by Caspase-3 may represent an important process for maintaining tissue homeostasis, it may limit the efficiency of current cancer therapy by promoting cell proliferation in those cancer cells resistant to radio- or chemotherapy. We discuss recent evidence in support of such a role for Caspase-3, and discuss its therapeutic implication.     

Identification of novel DNA methylation inhibitors via a two-component reporter gene system

Background

The extracellular calcium-sensing receptor (CaSR) belongs to family C of the G protein coupled receptors. Whether the CaSR is expressed in the pulmonary artery (PA) is unknown.

Methods

The expression and distribution of CaSR were detected by RT-PCR, Western blotting and immunofluorescence. PA tension was detected by the pulmonary arterial ring technique, and the intracellular calcium concentration ([Ca²⁺]_i) was detected by a laser-scanning confocal microscope.

Results

The expressions of CaSR mRNA and protein were found in both rat pulmonary artery smooth muscle cells (PASMCs) and PAs. Increased levels of [Ca²⁺]_o (extracellular calcium concentration) or Gd³⁺ (an agonist of CaSR) induced an increase of [Ca²⁺]_i and PAs constriction in a concentration-dependent manner_. In addition, the above-mentioned effects of Ca²⁺ and Gd³⁺ were inhibited by U73122 (specific inhibitor of PLC), 2-APB (specific antagonist of IP₃ receptor), and thapsigargin (blocker of sarcoplasmic reticulum calcium ATPase).

Conclusions

CaSR is expressed in rat PASMCs, and is involved in regulation of PA tension by increasing [Ca²⁺]_i through G-PLC-IP₃ pathway.     

Seropositivity for CMV and IL-6 levels are associated with grip strength and muscle size in the elderly

Background

Sarcopenia is an important cause of morbidity and mortality in older adults, with immunosenescence and inflammation being possible underlying mechanisms. We investigated the relationship between latent cytomegalovirus (CMV) infection, Interleukin 6 (IL-6) levels, muscle size and strength in a group of healthy older community-dwelling people.

Methods

Participants were healthy volunteers from the Lothian Birth Cohort 1936 study. Participants had IL-6 level and CMV antibody titre measured at age 70 years and grip strength and a volumetric T1-weighted MRI brain scan (allowing measurement of neck muscle cross-sectional area (CSA)) at age 73. Markers of childhood deprivation were adjusted for in the analysis due to correlations between childhood deprivation and latent CMV infection.

Results

866 participants were studied; 448 men (mean age 72.48 years, sd 0.70) and 418 women (mean age 72.51 years, sd 0.72). In men, CMV seropositivity was associated with smaller neck muscle CSA (p = 0.03, partial eta squared = 0.01), even after adjustment for IL-6 levels. Neck muscle CSA was not associated with CMV seropositivity in women, or CMV antibody titre or IL-6 level in either sex. Grip strength associated negatively with IL-6 level (right grip strength p<0.00001, partial eta squared 0.032 and left grip strength p<0.00001, partial eta squared 0.027) with or without adjustment for CMV serostatus or antibody titre. CMV status and antibody titre were not significantly associated with grip strength in either hand.

Conclusion

These findings support the hypothesis that there is a relationship between markers of immunosenescence (i.e. CMV serostatus and IL6 level) and low muscle mass and strength and longitudinal studies in older cohorts are now required to investigate these relationships further.

     

Flat Feet,Happy Feet? Comparison of the Dynamic Plantar Pressure Distribution and Static Medial Foot Geometry between Malawian and Dutch Adults

In contrast to western countries, foot complaints are rare in Africa. This is remarkable, as many African adults walk many hours each day, often barefoot or with worn-out shoes. The reason why Africans can withstand such loading without developing foot complaints might be related to the way the foot is loaded. Therefore, static foot geometry and dynamic plantar pressure distribution of 77 adults from Malawi were compared to 77 adults from the Netherlands. None of the subjects had a history of foot complaints. The plantar pressure pattern as well as the Arch Index (AI) and the trajectory of the center of pressure during the stance phase were calculated and compared between both groups. Standardized pictures were taken from the feet to assess the height of the Medial Longitudinal Arch (MLA). We found that Malawian adults: (1) loaded the midfoot for a longer and the forefoot for a shorter period during roll off, (2) had significantly lower plantar pressures under the heel and a part of the forefoot, and (3) had a larger AI and a lower MLA compared to the Dutch. These findings demonstrate that differences in static foot geometry, foot loading, and roll off technique exist between the two groups. The advantage of the foot loading pattern as shown by the Malawian group is that the plantar pressure is distributed more equally over the foot. This might prevent foot complaints.     

Molecular screening of Chinese medicinal plants for progestogenic and anti-progestogenic activity

Estrogen and progestins have adverse effects, and many of these adverse effects are caused by progestins. Due to this, many women choose to use botanical alternatives for hormone replacement therapy, which does not trigger steroidogenic properties. Therefore, it is necessary to screen these herbs for progestogenic and anti-progestogenic properties. Extract of 13 Chinese medicinal plants were analysed for progestogenic and anti-progestogenic activities by using progesterone response element-driven luciferase reporter gene bioassay. MTT assay was carried out to investigate the cytotoxic effect of herb extract on PAE cells. Among the 13 herbs, Dipsacus asperoides extract exhibited progestogenic activity, and 10 species – Cortex eucommiae, Folium artemisiae argyi, Glycyrrhiza uralensis, Angelica sinensis, Atractylodes macrocephala koidz, Scutellaria baicalensis, Cuscuta chinensis, Euscaphis japonica, Ailanthus altissima, and Dioscorea opposita – were recognized to have anti-progestogenic like activities. Extract of Dipsacus asperoides demonstrated dose-dependent progestogenic activity, and the progestogenic activity of 100 μg/mL extracts was equivalent to 31.45 ng/mL progesterone activity. Herbs extracts that exhibited anti-progestogenic-like activity also inhibited the 314.46 ng/mL progesterone activity in a dose-response manner. None of the herb extracts shown significant toxic effect on PAE cells at 40–100 μg/mL compared to control. This discovery will aid selection of suitable herbs for hormone replacement therapy.