Abstract
Neurogenesis in the subventricular zone (SVZ) is regulated by diffusible factors and cell–cell contacts. In vivo, SVZ stem cells are associated with the abluminal surface of blood vessels and such interactions are thought to regulate their neurogenic capacity. SVZ neural stem cells (NSCs) have been described to contact endothelial-derived laminin via α6β1 integrin. To elucidate whether heterocellular contacts with brain endothelial cells (BEC) regulate SVZ cells neurogenic capacities, cocultures of SVZ neurospheres and primary BEC, both obtained from C57BL/6 mice, were performed. The involvement of laminin-integrin interactions in SVZ homeostasis was tested in three ways. Firstly, SVZ cells were analyzed following incubation of BEC with the protein synthesis inhibitor cycloheximide (CHX) prior to coculture, a treatment expected to decrease membrane proteins. Secondly, SVZ cells were cocultured with BEC in the presence of an anti-α6 integrin neutralizing antibody. Thirdly, BEC were cultured with β1−/− SVZ cells. We showed that contact with BEC supports, at least in part, proliferation and stemness of SVZ cells, as evaluated by the number of BrdU positive (+) and Sox2+ cells in contact with BEC. These effects are dependent on BEC-derived laminin binding to α6β1 integrin and are decreased in cocultures incubated with anti-α6 integrin neutralizing antibody and in cocultures with SVZ β1−/− cells. Moreover, BEC-derived laminin sustains stemness in SVZ cell cultures via activation of the Notch and mTOR signaling pathways. Our results show that BEC/SVZ interactions involving α6β1 integrin binding to laminin, contribute to SVZ cell proliferation and stemness.
Highlights
Stem cells of the rodent subventricular zone (SVZ) reside in a specific microenvironment: the neurogenic niche, which contributes to the maintenance of their intrinsic capacities
The maximum duration of the coculture experiment was determined according to the capacity of brain endothelial cells (BEC) to survive in serum-free medium (SFM) and SFM conditioned by SVZ cells
Levels of Sox2 protein in free-floating neurospheres cultures in the presence of epidermal growth factor (EGF) and fibroblast growth factor-2 (FGF-2) were evaluated as positive controls as these conditions promote stemness in SVZ cells (Figure 6A). These results indicate that laminin-1 sustains stemness in SVZ cells
Summary
Stem cells of the rodent subventricular zone (SVZ) reside in a specific microenvironment: the neurogenic niche, which contributes to the maintenance of their intrinsic capacities. Stem/progenitor cells contact EC directly in patches of vessels lacking astrocytes endfeet and pericyte coverage (Tavazoie et al, 2008). These contacts support proliferation and self-renewal in tumor cells via activation of the Notch signaling pathway (Hovinga et al, 2010; Zhu et al, 2011). In the SVZ, adhesion of B and C cells to vessels is dependent on the expression of transmembrane α6β1 integrin that binds ECderived ECM laminin (Shen et al, 2008; Kokovay et al, 2010) Whether these cell–cell contacts directly sustain proliferation and self-renewal remains to be shown
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
