Lysosomal-associated membrane protein 2 isoforms are differentially affected in early Parkinson's disease
MOVEMENT DISORDERS
Authors: Murphy, Karen E.; Gysbers, Amanda M.; Abbott, Sarah K.; Spiro, Adena S.; Furuta, Akiko; Cooper, Antony; Garner, Brett; Kabuta, Tomohiro; Halliday, Glenda M.
Abstract
Lysosomes are the primary catabolic compartment for the degradation of intracellular proteins through autophagy. The presence of abnormal intracellular -synuclein-positive aggregates in Parkinson's disease (PD) indicates that the degradative capacity of lysosomes is impaired in PD. Specific dysfunction of chaperone-mediated autophagy (CMA) in PD is suggested by reductions in the CMA membrane receptor, lysosomal-associated membrane protein (LAMP) 2A, although whether LAMP2A is the only LAMP2 isoform affected by PD is unknown. Messenger RNA (mRNA) and protein expression of all three LAMP2 isoforms was assessed in brain extracts from regions with and without PD-related increases in -synuclein in autopsy samples from subjects in the early pathological stage of PD (n=9), compared to age- and postmortem delay-matched controls (n=10). In the early stages of PD, mRNA expression of all LAMP2 isoforms was not different from controls, with LAMP2B and LAMP2C protein levels also unchanged in PD. The selective loss of LAMP2A protein directly correlated with the increased levels of -synuclein and decreased levels of the CMA chaperone heat shock cognate protein 70 in the same PD samples, as well as with the accumulation of cytosolic CMA substrate proteins. Our data show that LAMP2 protein isoforms are differentially affected in the early stages of PD, with LAMP2A selectively reduced in association with increased -synuclein, and suggests that dysregulation of CMA-mediated protein degradation occurs before substantial -synuclein aggregation in PD. (c) 2015 International Parkinson and Movement Disorder Society.
Citrinin exposure disrupts organelle distribution and functions in mouse oocytes
ENVIRONMENTAL RESEARCH
Authors: Sun, Ming-Hong; Li, Xiao-Han; Xu, Yao; Xu, Yi; Pan, Zhen-Nan; Sun, Shao-Chen
Abstract
Citrinin (CTN) is a secondary fungal metabolite produced by several species of Aspergillins and Penicillins, and it is widely found in vegetable-derived foods such as cereals and fermented rice-based food supplements. Previous studies indicated that CTN had immunotoxicity, hepatotoxicity, nephrotoxicity, and reproductive toxicity, which caused severe effects on human and animal health. However, the potential toxicity of CTN on the organelles of mouse oocytes is still unclear. In this study, we showed that the exposure to 30 mu M CTN significantly reduced the developmental capacity of mouse oocytes. Our results revealed that mitochondria exhibited abnormal distribution and mitochondrial membrane potential decreased under CTN exposure. And the endoplasmic reticulum (ER) failed to accumulate to the spindle periphery, which is accompanied by the occurrence of ER stress, showing with increased GRP78 expression. We also found that similar with ER, the Golgi apparatus showed homogenous localization pattern after CTN exposure, and the vesicle transport was disturbed, showing with aberrant expression and localization of Rab11a. Moreover, our results indicated that CTN exposure increased the expression of LAMP2, indicating the induction of lysosomal damage. In summary, our study showed that CTN exposure to mouse oocytes was toxic to the distribution and functions of organelles, which further led to a decrease of oocyte quality.