Dataset Information

LC3A Silencing Hinders Aggresome Vimentin Cage Clearance in Primary Choroid Plexus Carcinoma.

ABSTRACT: Aggresomes are transient microtubule-dependent inclusion bodies that sequester misfolded proteins and are ultimately removed by autophagy. Here we report the generation of a choroid plexus carcinoma cell line; Children's Cancer Hospital Egypt (CCHE)-45, which is characterized by the constitutive formation of aggresomes. When examining the autophagy pathway as the main route for aggresomes clearance, CCHE-45 cells displayed increased autophagy flux mediated by MAP1LC3B. MAP1LC3A-Variant1 gene expression was silenced by promoter methylation. Restoring MAP1LC3A-Variant1 expression resulted in the formation of MAP1LC3A positive autophagosmes and the disruption of the aggresomes' vimentin cage independent of MAP1LC3B positive autophagosomes. Our data supports the notion that basal quality control autophagy and vimentin cage clearance in CCHE-45 are mediated by MAP1LC3A. Hence we propose that absence of MAP1LC3A disrupts the autophagic pathway and leads to the failure of aggresome vimentin cage degradation. Consequently, this could represent a targetable pathway in autophagy-dependent cancers.

SUBMITTER: Nassar M

PROVIDER: S-EPMC5556083 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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LC3A Silencing Hinders Aggresome Vimentin Cage Clearance in Primary Choroid Plexus Carcinoma.

Nassar Marwa M Samaha Heba H Ghabriel Myret M Yehia Maha M Taha Hala H Salem Sherin S Shaaban Khaled K Omar Mariam M Ahmed Nabil N El-Naggar Shahenda S

Scientific reports 20170814 1

Aggresomes are transient microtubule-dependent inclusion bodies that sequester misfolded proteins and are ultimately removed by autophagy. Here we report the generation of a choroid plexus carcinoma cell line; Children's Cancer Hospital Egypt (CCHE)-45, which is characterized by the constitutive formation of aggresomes. When examining the autophagy pathway as the main route for aggresomes clearance, CCHE-45 cells displayed increased autophagy flux mediated by MAP1LC3B. MAP1LC3A-Variant1 gene exp ...[more]

PMID: 28808307

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Project description:BackgroundAlthough fibroblast growth factor (Fgf) signalling plays crucial roles in several developing and mature tissues, little information is currently available on expression of Fgf2 during early choroid plexus development and whether Fgf2 directly affects the behaviour of the choroid plexus epithelium (CPe). The purpose of this study was to investigate expression of Fgf2 in rodent and human developing CPe and possible function of Fgf2, using in vitro models. The application of Fgf2 to brain in vivo can affect the whole tissue, making it difficult to assess specific responses of the CPe.MethodsExpression of Fgf2 was studied by immunohistochemistry in rodent and human embryonic choroid plexus. Effects of Fgf2 on growth, secretion, aggregation and gene expression was investigated using rodent CPe vesicles, a three-dimensional polarized culture model that closely mimics CPe properties in vivo, and rodent CPe monolayer cultures.ResultsFgf2 was present early in development of the choroid plexus both in mouse and human, suggesting the importance of this ligand in Fgf signalling in the developing choroid plexus. Parallel analysis of Fgf2 expression and cell proliferation during CP development suggests that Fgf2 is not involved in CPe proliferation in vivo. Consistent with this observation is the failure of Fgf2 to increase proliferation in the tri-dimensional vesicle culture model. The CPe however, can respond to Fgf2 treatment, as the diameter of CPe vesicles is significantly increased by treatment with this growth factor. We show that this is due to an increase in cell aggregation during vesicle formation rather than increased secretion into the vesicle lumen. Finally, Fgf2 regulates expression of the CPe-associated transcription factors, Foxj1 and E2f5, whereas transthyretin, a marker of secretory activity, is not affected by Fgf2 treatment.ConclusionFgf2 expression early in the development of both human and rodent choroid plexus, and its ability to modulate behaviour and gene expression in CPe, supports the view that Fgf signalling plays a role in the maintenance of integrity and function of this specialized epithelium, and that this role is conserved between rodents and humans.

Project description:The choroid plexus (CP) consists of specialized ependymal cells and underlying blood vessels and stroma producing the bulk of the cerebrospinal fluid (CSF). CP epithelial cells are considered the site of the internal blood-cerebrospinal fluid barrier, show epithelial characteristics (basal lamina, tight junctions), and express aquaporin-1 (AQP1) apically. In this study, we analyzed the expression of aquaporins in the human CP using immunofluorescence and qPCR. As previously reported, AQP1 was expressed apically in CP epithelial cells. Surprisingly, and previously unknown, many cells in the CP epithelium were also positive for aquaporin-4 (AQP4), normally restricted to ventricle-lining ependymal cells and astrocytes in the brain. Expression of AQP1 and AQP4 was found in the CP of all eight body donors investigated (3 males, 5 females; age 74-91). These results were confirmed by qPCR, and by electron microscopy detecting orthogonal arrays of particles. To find out whether AQP4 expression correlated with the expression pattern of relevant transport-related proteins we also investigated expression of NKCC1, and Na/K-ATPase. Immunostaining with NKCC1 was similar to AQP1 and revealed no particular pattern related to AQP4. Co-staining of AQP4 and Na/K-ATPase indicated a trend for an inverse correlation of their expression. We hypothesized that AQP4 expression in the CP was caused by age-related changes. To address this, we investigated mouse brains from young (2 months), adult (12 months) and old (30 months) mice. We found a significant increase of AQP4 on the mRNA level in old mice compared to young and adult animals. Taken together, we provide evidence for AQP4 expression in the CP of the aging brain which likely contributes to the water flow through the CP epithelium and CSF production. In two alternative hypotheses, we discuss this as a beneficial compensatory, or a detrimental mechanism influencing the previously observed CSF changes during aging.

Dataset Information

LC3A Silencing Hinders Aggresome Vimentin Cage Clearance in Primary Choroid Plexus Carcinoma.

Publications

LC3A Silencing Hinders Aggresome Vimentin Cage Clearance in Primary Choroid Plexus Carcinoma.

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