ABSTRACT
The dystrophin-associated-protein complex (DAPC) has been extensively characterized in the central nervous system where it is localized both in neuronal and glial cells. Few studies have characterized this complex in the neurohypophysis. To further study this complex in pituicytes, the resident astroglia of the neurophypophysis, we used adult pituicyte cultures and determined the expression and localization of dystrophins/utrophins and the DAPC by RT-PCR, western blotting and immunofluorescence. Our data show that the pituicytes express dystrophins, utrophins and several members of the DAPC including dystroglycans, δ-, γ-sarcoglycans, α-dystrobrevin-1 and α1-syntrophin. Double immunofluorescence analysis shows that laminin colocalizes with dystroglycan, suggesting that similarly to muscle and astrocytes, the DAPC interacts with the extracellular matrix in pituicytes. Collectively these findings show that dystrophins/utrophins and members of the DAPC are expressed in pituicytes where they may form multiprotein complexes and play a role in the retraction-reinsertion of pituicyte endfeet during specific physiological conditions.
Subject(s)
Dystrophin-Associated Protein Complex/metabolism , Dystrophin/metabolism , Pituitary Gland, Posterior/cytology , Protein Isoforms/metabolism , Utrophin/metabolism , Animals , Cells, Cultured , Dystrophin/genetics , Dystrophin-Associated Protein Complex/chemistry , Dystrophin-Associated Protein Complex/genetics , Dystrophin-Associated Proteins/genetics , Dystrophin-Associated Proteins/metabolism , Gene Expression Profiling , Humans , Laminin/genetics , Laminin/metabolism , Male , Pituitary Gland, Posterior/chemistry , Pituitary Gland, Posterior/metabolism , Protein Isoforms/genetics , Rats , Rats, Wistar , Utrophin/geneticsABSTRACT
Like the majority of tumor cells, ovarian cancer cell growth is critically dependent on their neovascularization. Adhesion molecules and cellular events that lead to ovarian tumor cell interactions with endothelial extracellular matrix surrounding the vasculature are poorly identified. To understand the role of alphavbeta3 integrin and its ligand fibronectin in this process, we used in vitro coculture models with IGROV1 human ovarian adenocarcinoma cell line and human umbilical vein endothelial cells (HUVEC). Adhesion assays revealed a strong ability of IGROV1 cells to adhere to HUVEC-ECM. alphavbeta3 is mainly implicated and seems to cooperate with alpha5beta1 integrin in this event. Immunofluorescence staining revealed the presence of alphavbeta3 and alpha5beta1 in IGROV1 cells adhering on HUVEC-ECM at regions of cell sub-stratum contacts. Furthermore, our data showed the absence of fibronectin staining in IGROV1 cells and the disruption of the HUVEC-ECM fibrillar fibronectin network under IGROV1 cell influence. In situ experiments in ovarian neoplastic tissue corroborated the absence of fibronectin in the tumor and its strong detection in vasculature. These findings suggest the active participation of alphavbeta3 and alpha5beta1 integrins and the reorganization of endothelial fibronectin during the adhesion of IGROV1 cells to HUVEC-ECM whereas IGROV1 cells seem to be unable to synthesize fibronectin. Thus, fibronectin integrin receptors expressed by ovarian tumor cells and endothelial fibronectin may be of importance in ovarian carcinoma neovascularization and during tumor-vasculature interactions.
