Parkinson's disease-associated iPLA2-VIA/PLA2G6 regulates neuronal functions and α-synuclein stability through membrane remodeling.

Mutations in the iPLA2-VIA/PLA2G6 gene are responsible for PARK14-linked Parkinson's disease (PD) with α-synucleinopathy. However, it is unclear how iPLA2-VIA mutations lead to α-synuclein (α-Syn) aggregation and dopaminergic (DA) neurodegeneration. Here, we report that iPLA2-VIA-deficient Drosophila exhibits defects in neurotransmission during early developmental stages and progressive cell loss throughout the brain, including degeneration of the DA neurons. Lipid analysis of brain tissues reveals that the acyl-chain length of phospholipids is shortened by iPLA2-VIA loss, which causes endoplasmic reticulum (ER) stress through membrane lipid disequilibrium. The introduction of wild-type human iPLA2-VIA or the mitochondria-ER contact site-resident protein C19orf12 in iPLA2-VIA-deficient flies rescues the phenotypes associated with altered lipid composition, ER stress, and DA neurodegeneration, whereas the introduction of a disease-associated missense mutant, iPLA2-VIA A80T, fails to suppress these phenotypes. The acceleration of α-Syn aggregation by iPLA2-VIA loss is suppressed by the administration of linoleic acid, correcting the brain lipid composition. Our findings suggest that membrane remodeling by iPLA2-VIA is required for the survival of DA neurons and α-Syn stability.

Identification of preneoplastic lesions as mucin-depleted foci in patients with sporadic colorectal cancer.

In experimental models, mucin-depleted foci (MDF), formed by dysplastic crypts devoid of mucin production have been recognized to be correlated with colorectal carcinogenesis and to serve as preneoplastic lesions of colorectal cancer (CRC). In humans, there is only one report of identification of MDF in patients with familial adenomatous polyposis and CRC; however, the histological characteristics of human MDF are not discussed extensively in the report. In the present study, colonic samples from 53 patients with sporadic CRC were stained with Alcian blue and examined for the presence of MDF. Subsequently, the samples were examined for the presence of aberrant crypt foci (ACF) by methylene blue staining. We classified MDF into two categories: flat-MDF and protruded-MDF (having the characteristics of both ACF and MDF). We found a total of 354, 41 and 19 colonic mucosal lesions with a mean multiplicity of 44, 38.9 and 66.9 crypts (ACF, flat-MDF and protruded-MDF, respectively). The density of MDF was 0.0082 lesions/cm(2) . The ACF identified in sporadic CRC patients corresponded to hyperplastic or non-dysplasic lesions. However, MDF identified in these patients corresponded to low-grade dysplasia. In addition, we found that Paneth cell metaplasia and inflammatory cell infiltration were specific histological features of MDF. These histological characteristics are reported to be associated with the development of CRC. Therefore, our results indicate that MDF might represent preneoplastic lesions in human colorectal carcinogenesis.

Regulation of membrane dynamics by Parkinson's disease-associated genes.

Parkinson's disease (PD), the second most common neurodegenerative disease after Alzheimer's disease, develops sporadically, and its cause is unknown. However, 5-10% of PD cases are inherited as monogenic diseases, which provides a chance to understand the molecular mechanisms underlying neurodegeneration. Over 20 causative genes have already been identified and are being characterized. These PD-associated genes are broadly classified into two groups: genes involved in mitochondrial functions and genes related to membrane dynamics such as intracellular vesicle transport and the lysosomal pathway. In this review, we summarize the latest findings on the mechanism by which members of the latter group of PD-associated genes regulate membrane dynamics, and we discuss how mutations of these genes lead to dopaminergic neurodegeneration.

[Inhibition of Sorbaria sorbifolia on proliferarion of hepatoma HepG-2 cell line].

OBJECTIVE: To investigate the inhibition of Sorbaria sorbifolia on proliferation hepatoma HepG-2 cells, and to explore the antineoplastic mechanism of Sorbaria sorbifolia. METHODS: MTT assay was used to examine the effect of Sorbaria sorbifolia on the proliferation of HepG-2 cell and flow cytometry was used for the cell cycle distribution. Apoptosis of HepG-2 cell was investigated further by means of inverted microscope, HE staining, transmission electron microscopy and expression of apoptosis-associated gene bcl-2 and p53 were determined by immunohistochemical method. RESULTS: Sorbaria sorbifolia inhibited the proliferation of HepG-2 cell and the effects were in a time-and-concentration dependent manner. Sorbaria sorbifolia could also induce apoptosis, the G2/M phase was arrested and the ratio of apoptosis was significantly difference with that of control group, respectively. The expressions of apoptosis-associated gene bcl-2 and p53 had changed significantly, respectively. CONCLUSION: Sorbaria sorbifolia inhibits proliferation of HepG-2 cells via induction of apoptosis and cell cycle arrest.

Reduced TDP-43 Expression Improves Neuronal Activities in a Drosophila Model of Perry Syndrome.

Parkinsonian Perry syndrome, involving mutations in the dynein motor component dynactin or p150Glued, is characterized by TDP-43 pathology in affected brain regions, including the substantia nigra. However, the molecular relationship between p150Glued and TDP-43 is largely unknown. Here, we report that a reduction in TDP-43 protein levels alleviates the synaptic defects of neurons expressing the Perry mutant p150G50R in Drosophila. Dopaminergic expression of p150G50R, which decreases dopamine release, disrupts motor ability and reduces the lifespan of Drosophila. p150G50R expression also causes aggregation of dense core vesicles (DCVs), which contain monoamines and neuropeptides, and disrupts the axonal flow of DCVs, thus decreasing synaptic strength. The above phenotypes associated with Perry syndrome are improved by the removal of a copy of Drosophila TDP-43 TBPH, thus suggesting that the stagnation of axonal transport by dynactin mutations promotes TDP-43 aggregation and interferes with the dynamics of DCVs and synaptic activities.

Pre-neoplastic lesion, mucin-depleted foci, reveals de novo high-grade dysplasia in rat colon carcinogenesis.

Aberrant crypt foci (ACF) and mucin-depleted foci (MDF) have recently been recognized as pre-neoplastic lesions in the colon of carcinogen-treated rodents. In the present study, we analyzed the sequential development of ACF and MDF histopathologically in the colon of rats from 5 to 40 weeks after DMH treatment. The numbers of ACF per colon increased over time during the experiment, and were much higher than the number in tumors, while the number of MDF per colon remained unchanged from the early stage (the 5th week after carcinogen exposure), and approximate to those in tumors. The incidence of ACF, which was much higher than that of tumors, also increased gradually in a time-dependent manner. The incidence of MDF, however, was similar to that of tumors and did not change significantly during the whole experiment. No lesion as dysplasia with high-grade (DHG) or adenocarcinoma (AC) were found in any large ACF from the 5th to 40th week histopathologically, whereas all of the large MDF showed DHG or AC features. Even at 5 weeks, MDF showed features of DHG. We classified these into two forms of MDF: flat and protruded MDF. At 40 weeks, the number of flat MDF per colon decreased significantly compared with that at 20 weeks (p<0.05), however, the number of protruded MDF per colon increased (p<0.01), and the percentage of DHG in a protruded MDF lesion decreased but that of AC increased remarkably. In conclusion, MDF may develop into cancer through the so-called 'de novo cancer' pathway.