The proteomic analysis of mouse choroid plexus secretome reveals a high protein secretion capacity of choroidal epithelial cells

Abstract

Choroid plexuses (CP) are involved in multiple functions related to their unique architecture and localization at the interface between the blood and cerebrospinal fluid compartments. These include the release by choroidal epithelial cells (CEC) of biologically active molecules, such as polypeptides, which are distributed globally to the brain. Here, we have used a proteomic approach to get an unbiased overview of the proteins that are secreted by primary cultures enriched in epithelial cells from mice CP. We identified a total of 43 proteins secreted through the classical vesicular pathway in CEC -conditioned medium. They include transport proteins, collagen subunits and other cell matrix proteins, proteases, protease inhibitors and neurotrophic factors. Treating CEC cultures with lipopolysaccharide, increased the secretion of four protein species and induced the release of two additional proteins. Our study also reveals a higher protein secretion capacity of CECs compared with other CP cells or cultured astrocytes. In conclusion, this study provides for the first time the characterization of the major proteins that are secreted by CECs. These proteins may play a critical role in neuronal growth, differentiation and function as well as in brain pathologies.

Matrix Metalloprotease 8-Dependent Extracellular Matrix Cleavage at the Blood-CSF Barrier Contributes to Lethality during Systemic Inflammatory Diseases

“…Not much is known about the composition and function of the ECM deposited along the outer surface of the basal side of the CP epithelial cells. Based on in vitro and in vivo analyses, several matrix proteins, such as thrombospondin, fibronectin, laminin, and collagen types I, III, IV, and XVIII, are believed to be present (Gabrion et al, 1998;Wei et al, 2000;Haselbach et al, 2001;Utriainen et al, 2004;Thouvenot et al, 2006;Thanos et al, 2011). Because MMP8 has collagenolytic activity, we speculated that MMP8 modulates the CP epithelial BM by degradating collagen of the basal lamina.…”

Adding a spatial dimension to postnatal ventricular-subventricular zone neurogenesis

“…Second, numerous patterning molecules are carried away from their source by the CSF (Thouvenot et al, 2006;Marques et al, 2011), creating signaling gradients ( Fig. 2A) and thus affecting V-SVZ microdomains differently (Sawamoto et al, 2006).…”

Physical Interaction of Calmodulin with the 5-Hydroxytryptamine2C Receptor C-Terminus Is Essential for G Protein-independent, Arrestin-dependent Receptor Signaling

“…Primary cultures enriched in choroid plexus epithelial cells (CECs) were prepared from 6-d-old Swiss mice as described previously (Thouvenot et al, 2006). Briefly, choroid plexuses from the fourth ventricle were rapidly dissected, incubated with pronase (0.3 mg/ml; Sigma-Aldrich) and type I DNase (25 g/ml; Sigma-Aldrich) in phosphate-buffered saline (PBS) containing 33 mM glucose (PBS-glucose) for 15 min at 37°C, and mechanically dissociated by eight forced passages through a 20-gauge needle.…”

“…The culture medium consisted of DMEM/F-12 supplemented with glucose (33 mM), glutamine (2 mM), NaHCO 3 (13 mM), HEPES buffer (5 mM; pH 7.4), penicillin-streptomycin (100 IU/ml and 100 g/ml, respectively), and 15% Nu-serum (BD Biosciences, Franklin Lakes, NJ). After 10 -12 d, cultures contained Ͼ80% of densely packed cells with a polygonal epitheliallike morphology and positively stained with an antibody against transthyretin, a specific marker of CECs in the CNS (Thouvenot et al, 2006). Cultured CECs were transfected after 7 d in culture by using Lipofectamine 2000, and the procedure used for HEK-293 cell transfection.…”