Role of cytosolic Calcium-dependent Phospholipase A2 in Alzheimer’s disease pathogenesis

Phospholipases (PLA2s) are a super family of enzymes characterized by the ability to specifically hydrolyze the sn-2 ester bond of phospholipids generating arachidonic acid, utilized in inflammatory responses and lysophospholipids involved in the control of cell membrane remodeling and fluidity. PLA2s have been so far considered a crucial element in the etiopathogenesis of several neurological diseases such as cerebral ischemia, multiple sclerosis, Parkinson disease and Alzheimer’s disease (AD). In AD the role of β-amyloid (Aβ) fragments is well-established although still more elusive are the molecular events of the cascade that from the Aβ accumulation leads to neurodegeneration with its clinical manifestations. However, it is well-known that inflammation and alteration of lipid metabolism are common features of AD brains. Findings obtained from in vitro studies, animal models and human brain imaging analysis point towards PLA2 as a key molecule in the onset and maintenance of the neurodegenerative mechanism(s) of AD. In this review we have focused on the molecular and biological evidence of the involvement of PLA2s in the pathogenesis of AD. An insight into the molecular mechanism(s) underlying the action and the regulation of PLA2 is of tremendous interest in the pharmaceutical and biotechnology industry in developing selective and potent inhibitors able to modulate the onset and/or the outcome of AD

Ruta graveolens aqueous extract inhibits proliferation of undifferentiated neural cells and induces differentiated neurons reentry in cell cycle

Introduction: In CNS, aberrant proliferation causes cancer and im- paired survival of differentiated neurons induces neurodegenerative disorders. In order to find novel ther- apeutic targets able to inhibit aber- rant cell proliferation and/or enhance differentiated cells survival, we ana- lyzed properties of aqueous extract of Ruta graveolens on differentiated and proliferating neural cells. Ruta g. is currently used for its diuretic, sedative, and analgesic effects and recent studies described antiprolifer- ative effects on different cancer cells. Materials and methods: We used a mouse mesencephalic embryonic cell line, A1 mes-c-myc cells (A1) that are proliferating/undifferenti- ated in the presence of serum. They cease to proliferate and differentiate when serum is withdrawn and cAMP is added. Aqueous extracts (Ruta g. a.e.) were obtained from young leaves chopped, infused in boil- ing water and lyophilized. Extract concentrations of 10 mg/ml, 1 mg/ ml and 0.1 mg/ml were tested. Cell counting was performed by MTT assay and Trypan blue method. Cell cycle was analyzed by cytometry af- ter PI incorporation. Cell signalling was analyzed by western blotting. Results: Ruta g. a.e. inhibits A1 cells proliferation and induces increase in ERK phosphorylation. In presence of the ERK pathway inhibitor, PD, Ruta g. a.e. is unable to induce cell death indicating that ERK is involved in the Ruta g. effect on A1 proliferating cells. On the other hand, when Ruta g. a.e. is added, the number of dif- ferentiated A1 cells appears signifi- cantly higher as compared to control conditions and the analysis of the cell cycle showed an increased number of cells in G2/M phase in differentiated cells treated with Ruta g. a.e. Conclu- sions: Ruta g. a.e. could represent an interesting therapeutic tool since it is able at the same time to inhibit un- differentiated cell proliferation and to induce re-entry in the cell cycle of differentiated neurons

Cellular localization of ERK in the R6/2 mouse model of Huntington’s disease

Introduction: The mitogen-activated protein kinases (MAPKs superfamily comprises three major signaling pathways: the extracellular signal- regulated protein kinases (ERKs), the c-Jun N-terminal kinases or stressactivated protein kinases (JNKs/ SAPKs) and the p38 family of kinases. ERK signaling has been implicated in a number of neurodegenerative disorders, including Huntington’s disease (HD). Phosphorylation patterns of ERK and JNK are altered in cell models of HD. In this study,we aimed at studying the correlations between ERK and the neuronal vulnerability to HD degeneration in the R6/2 transgenic mouse model of HD. Materials and methods: Immunohistochemistry for phospho-ERK (p-ERK, the activated form of ERK) and dual label immunofluorescence for p-ERK and each of the striatal neuronalmarkers were employed on perfusion-fixed brain sections from R6/2 and wildtype mice. Results: Our study shows that striatal neurons, both spiny projection and interneurons, are completely devoid of p-ERK immunoreactivity in the wild-type mouse.Conversely, parvalbumin- labeled GABAergic interneurons of the striatum are highly enriched in p-ERK in the R6/2 mice, cholinergic and somatostatinergic interneurons are devoid of it. Interestingly, the parvalbuminergic interneuron subpopulation of the striatum is the only interneuron subset that is extremely prone to degenerate in HD. Conclusions: Thus, our study confirms and extends the concept that the expression of phosphorilated ERK is related to neuronal vulnerability and is implicated in the pathophysiology of cell death in HD

Tissue-specific and mosaic imprinting defects underlie opposite congenital growth disorders in mice

<div><p>Differential DNA methylation defects of <i>H19/IGF2</i> are associated with congenital growth disorders characterized by opposite clinical pictures. Due to structural differences between human and mouse, the mechanisms by which mutations of the <i>H19/IGF2</i> Imprinting Control region (IC1) result in these diseases are undefined. To address this issue, we previously generated a mouse line carrying a humanized IC1 (hIC1) and now replaced the wildtype with a mutant IC1 identified in the overgrowth-associated Beckwith-Wiedemann syndrome. The new humanized mouse line shows pre/post-natal overgrowth on maternal transmission and pre/post-natal undergrowth on paternal transmission of the mutation. The mutant hIC1 acquires abnormal methylation during development causing opposite <i>H19/Igf2</i> imprinting defects on maternal and paternal chromosomes. Differential and possibly mosaic <i>Igf2</i> expression and imprinting is associated with asymmetric growth of bilateral organs. Furthermore, tissue-specific imprinting defects result in deficient liver- and placenta-derived <i>Igf2</i> on paternal transmission and excessive <i>Igf2</i> in peripheral tissues on maternal transmission, providing a possible molecular explanation for imprinting-associated and phenotypically contrasting growth disorders.</p></div

Analysis of <i>H19</i> and <i>Igf2</i> expression in <i>H19</i>^{<i>hIC1</i>Δ<i>2</i>.<i>2/+</i>} newborn mice.

<p>(A) Histograms of total <i>H19</i> and <i>Igf2</i> expression in three different neonatal organs of <i>H19</i>^{<i>hIC1</i>Δ<i>2</i>.<i>2/+</i>} and <i>H19</i>^<i>+/+</i> littermates analysed by RT-qPCR. The mean value of <i>H19</i>^<i>+/+</i> is set arbitrarily as 1. NS, Not Significant. Bars represent the mean ± SEM. (B) Allele-specific expression of <i>H19</i> and <i>Igf2</i>. Dots indicate the percent expression of the maternal allele in each individual sample. The animals used for this study derived from three litters.</p

Somatic undergrowth on paternal transmission of the <i>H19</i>^{<i>hIC1</i>Δ<i>2</i>.<i>2</i>} allele.

<p>(A-C) Box plot of birth weights (A), growth charts (B), and box plots of organ weights at 14 weeks of age (C) of <i>H19</i>^{<i>+/hIC1</i>Δ<i>2</i>.<i>2</i>} and <i>H19</i>^<i>+/+</i> littermates. Box plots in (A) and (C) and growth chart in (B) are as in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1007243#pgen.1007243.g002" target="_blank">Fig 2</a>. (D-E) Box plot of embryo body and placenta weights of <i>H19</i>^{<i>+/hIC1</i>Δ<i>2</i>.<i>2</i>} (D) and <i>H19</i>^{<i>+/hIC1</i>} (E) mice at E15.5 compared with <i>H19</i>^<i>+/+</i> littermates. The animals used for this study derived from three (A-C) or two litters (D-E).</p