AD-linked, toxic NH2 human tau affects the quality control of mitochondria in neurons

Functional as well as structural alterations in mitochondria size, shape and distribution are precipitating, early events in progression of Alzheimer's Disease (AD). We reported that a 20\u201322 kDa NH2-tau fragment (aka NH2htau), mapping between 26 and 230 amino acids of the longest human tau isoform, is detected in cellular and animal AD models and is neurotoxic in hippocampal neurons. The NH2htau \u2013but not the physiological full-length protein\u2013 interacts with A\u3b2 at human AD synapses and cooperates with it in inhibiting the mitochondrial ANT-1-dependent ADP/ATP exchange. Here we show that the NH2htau also adversely affects the interplay between the mitochondria dynamics and their selective autophagic clear- ance. Fragmentation and perinuclear mislocalization of mitochondria with smaller size and density are early found in dying NH2htau-expressing neurons. The specific effect of NH2htau on quality control of mitochondria is accompanied by (i) net reduction in their mass in correlation with a general Parkin- mediated remodeling of membrane proteome; (ii) their extensive association with LC3 and LAMP1 autoph- agic markers; (iii) bioenergetic deficits and (iv) in vitro synaptic pathology. These results suggest that NH2htau can compromise the mitochondrial biology thereby contributing to AD synaptic deficits not only by ANT-1 inactivation but also, indirectly, by impairing the quality control mechanism of these organelles

AD-linked, toxic NH2 human tau affects the quality control of mitochondria in neurons

Functional as well as structural alterations in mitochondria size, shape and distribution are precipitating, early events in progression of Alzheimer's Disease (AD). We reported that a 20\u201322 kDa NH2-tau fragment (aka NH2htau), mapping between 26 and 230 amino acids of the longest human tau isoform, is detected in cellular and animal AD models and is neurotoxic in hippocampal neurons. The NH2htau \u2013but not the physiological full-length protein\u2013 interacts with A\u3b2 at human AD synapses and cooperates with it in inhibiting the mitochondrial ANT-1-dependent ADP/ATP exchange. Here we show that the NH2htau also adversely affects the interplay between the mitochondria dynamics and their selective autophagic clear- ance. Fragmentation and perinuclear mislocalization of mitochondria with smaller size and density are early found in dying NH2htau-expressing neurons. The specific effect of NH2htau on quality control of mitochondria is accompanied by (i) net reduction in their mass in correlation with a general Parkin- mediated remodeling of membrane proteome; (ii) their extensive association with LC3 and LAMP1 autoph- agic markers; (iii) bioenergetic deficits and (iv) in vitro synaptic pathology. These results suggest that NH2htau can compromise the mitochondrial biology thereby contributing to AD synaptic deficits not only by ANT-1 inactivation but also, indirectly, by impairing the quality control mechanism of these organelles

Role of the intravitreal growth factors in the pathogenesis of idiopathic epiretinal membrane

PURPOSE. The aim of the present study is to evaluate the roles of TGFs beta 1 and beta 2, glial cell line-derived neurotrophic factor (GDNF), and nerve growth factor (NGF) in the pathogenesis of idiopathic epiretinal membrane (ERM). METHODS. Eight patients, six males and two females, with an average age of 60.25 +/- 17.16 years (range, 33-75 years) who were affected by idiopathic ERM were enrolled in the study. All patients underwent standard pars plana vitrectomy surgery with membrane removal and specific ELISA was performed to evaluate TGF beta 1, TGF beta 2, GDNF, and NGF in the vitreous samples. This was repeated after acidification of the samples with hydrochloric acid. RESULTS. Before acidification, ELISA analysis revealed a significant increase of TGF beta 2 in the samples with idiopathic ERM (327.98 +/- 99.58 pg/mL; range, 206.864-466.235 pg/mL) compared to the control group (187.17 +/- 58.20 pg/mL; range, 132.758-271.707 pg/mL; t = 3.4; P < 0.05). A statistically significant difference was also obtained after acidification of the samples (618.15 +/- 201.43 pg/mL; range, 409.795-866.215 pg/mL compared to 265.04 +/- 98.15 pg/mL; range, 152.478-352.101 pg/mL; t = 4.5; P < 0.05). Notably, before acidification the differences in NGF between the two groups were not statistically significant (t = 0.79; P = 0.46), while after acidification a significant increase of the NGF levels in ERM samples was found in comparison with the control group (723.41 +/- 235.4 vs. 242.84 +/- 104.61; t = 3; P < 0.05). CONCLUSIONS. The present study reveals that TGF beta 2 and NGF are associated with idiopathic ERMs, suggesting a novel compensatory mechanism so far never proposed. (Invest Ophthalmol Vis Sci. 2011;52:5786-5789) DOI:10.1167/iovs.10-711

Type 2 Transglutaminase, mitochondria and Huntington's disease: Menage a trois

Mitochondria produce the bulk of cellular energy and work as decisional "hubs" for cellular responses by integrating different input signals. The determinant in the physiopathology of mammals, they attract major attention, nowadays, for their contribution to brain degeneration. How they can withstand or succumb to insults leading to neuronal death is an object of great attention increasing the need for a better understanding of the interplay between inner and outer mitochondrial pathways residing in the cytosol. Of the latter, those dictating protein metabolism and therefore influencing the quality function and control of the organelle are of our most immediate interest and here we describe the Transglutaminase type 2 (TG2) contribution to mitochondrial function, dysfunction and neurodegeneration. Besides reviewing the latest evidences we share also the novel ones on the IF1 pathway depicting a molecular conduit governing mitochondrial turnover and homeostasis relevant to envisaging preventive and therapeutic strategies to respectively predict and counteract deficiencies associated with deregulated mitochondrial function in neuropathology