Adipose stromal cells-secreted neuroprotective media against neuronal apoptosis

Transplantation of pluripotent adipose stem/stromal cells (ASC) alleviates tissue damage and improves functional deficits in both stroke and cardiovascular disease animal models. Recent studies indicate that the primary mechanism of ASC-induced repair may not be directly related to tissue regeneration through differentiation, but rather through paracrine mechanisms provided by secreted pro-survival and repair-inducing trophic factors. In this study, we have found that ASC-conditioned medium (ASC-CM) potently protected cerebellar granule neurons (CGN) from apoptosis induced by serum and potassium deprivation. Neural cell protection was mostly attributable to activated caspase-3 and Akt-mediated neuroprotective pathway signaling. Specific neutralization of neurotrophic factor activity demonstrated that serum and potassium deprivation-induced Akt-mediated neuroprotection and caspase-3-dependent apoptosis were mainly modulated by IGF-1. These data suggest that of the many neuroprotective factors secreted by ASC, IGF-1 is the major factor that mediates protection against serum and potassium deprivation-induced CGN apoptosis. This study establishes a mechanistic basis supporting the therapeutic application of ASC for neurological disorders, specifically through paracrine support provided by trophic factor secretion.

Caffeic acid phenethyl ester prevents cerebellar granule neurons (CGNs) against glutamate-induced neurotoxicity

Caffeic acid phenethyl ester (CAPE) is an active component of propolis obtained from honeybee hives and is found to have the following properties: anti-mitogenic, anti-carcinogenic, anti-inflammatory, immunomodulatory, and antioxidant. Recent reports suggest that CAPE also has a neuronal protective property against ischemic injury. Since excitotoxicity may play an important role in ischemia, in this study, we investigated whether CAPE could directly protect neurons against excitotoxic insult. We treated cultured rat cerebellar granule neurons (CGNs) with excitotoxic concentrations of glutamate in the presence or absence of CAPE and found that CAPE markedly protected neurons against glutamate-induced neuronal death in a concentration-dependent fashion. Glutamate-induced CGNs death is associated with time-dependent activation of caspase-3 and phosphorylation of p38, both events of which can be blocked by CAPE. Treating CGNs with specific inhibitors of these two enzymes together exerts a synergistic neuroprotective effect, similar to the neuroprotective effect of CAPE exposure. These results suggest that CAPE is able to block glutamate-induced excitotoxicity by inhibiting phosphorylation of p38 and caspase-3 activation. This finding may further help understanding of the mechanism of glutamate-induced neuronal death and CAPE-induced neuroprotection against excitotoxicity.

The widely conserved Era G-protein contains an RNA-binding domain required for Era function in vivo

Era is a small G-protein widely conserved in eubacteria and eukaryotes. Although essential for bacterial growth and implicated in diverse cellular processes, its actual function remains unclear. Several lines of evidence suggest that Era may be involved in some aspect of RNA biology. The GTPase domain contains features in common with all G-proteins and is required for Era function in vivo. The C-terminal domain (EraCTD) bears scant similarity to proteins outside the Era subfamily. On the basis of sequence comparisons, we argue that the EraCTD is similar to, but distinct from, the KH RNA-binding domain. Although both contain the consensus VIGxxGxxI RNA-binding motif, the protein folds are probably different. We show that bacterial Era binds RNA in vitro and can form higher-order RNA-protein complexes. Mutations in the VIGxxGxxI motif and other conserved residues of the Escherichia coli EraCTD decrease RNA binding in vitro and have corresponding effects on Era function in vivo, including previously described effects on cell division and chromosome partitioning. Importantly, mutations in L-66, located in the predicted switch II region of the E. coli Era GTPase domain, also perturb binding, leading us to propose that the GTPase domain regulates RNA binding in response to unknown cellular cues. The possible biological significance of Era RNA binding is discussed.

A Study on the lack of [methyl-(3)H] thymidine uptake and incorporation by chemolithotrophic bacteria

Five chemolithotrophic bacteria were tested for their ability to incorporate [methyl-(3)H] thymidine. None of the bacteria incorporated the label, even after incubation for 24 hours. The inability of these bacteria to incorporate thymidine appears to be due to an absence of transport mechanisms for exogenous nucleosides. As a result of these findings, it is concluded that activities deduced from labeled thymidine incorporation measurements probably do not include the activity of chemolithotrophic bacteria.

Effects of Light and CO on the Survival of a Marine Ammonium-Oxidizing Bacterium during Energy Source Deprivation

The chemolithotrophic ammonium-oxidizing bacterium Nitrosomonas cryotolerans responds uniquely to nutrient deprivation by lowering its endogenous respiration and anabolic processes to undetectable levels during starvation, thus appearing to enter a dormant state. To ascertain whether this state protects the cells from further stresses (as seen with endospore-forming bacteria), the starved cells were subjected to two known inhibitors, CO and light. It was found that long-term-starved cells were less resistant than freshly starved cells to light inhibition. Both long-term-starved cells and freshly starved cells were unaffected by CO.