The glycoprotein fibulin‐3 regulates morphology and motility of olfactory ensheathing cells in vitro

Abstract

The primary olfactory pathway in adult mammals has retained a remarkable potential for self-repair. A specialized glial cell within the olfactory nerve, called olfactory ensheathing cell (OEC), and their associated extracellular matrix are thought to play an important role during regenerative events in this system. To gain insight into novel molecules that could mediate the OEC-supported growth of axons within the olfactory nerve, gene expression profiling experiments were conducted which revealed high expression of the glycoprotein fibulin-3 in OECs. This observation was confirmed with quantitative PCR. In vivo, the distribution of all members of the fibulin family, fibulin-3 included, was localized to the lamina propria underneath the olfactory epithelium, in close association within olfactory nerve bundles. To manipulate fibulin-3 gene expression in cultured OECs, lentiviral vector constructs were designed to either transgenically express or knock-down fibulin-3. Experimental data showed that increased levels of fibulin-3 induced profound morphological changes in cultured OECs, impeded with their migratory abilities and also suppressed OEC-mediated neurite outgrowth. Knock-down of fibulin-3 levels resulted in reduced OEC proliferation. In conclusion, the data provide novel insights into a putative role for fibulin-3 in the regulation of cell migration and neurite outgrowth within the primary olfactory pathway.

The Migration of Olfactory Ensheathing Cells during Development and Regeneration

“…Only 4 factors have been identified to functionally modulate OEC migration, 3 of which are known modulators of axonal extension (glial derived neurotrophic factor, GDNF, Nogo-66 and Slit-2) [46,47,48], and 1 extracellular matrix protein, fibulin 3 [49]. Because OECs are regarded as such important regulators of axon growth and guidance, and particularly since we have recently shown that an increased OEC migration rate leads to enhanced axon growth [22], a clear characterisation of how migration of OECs is regulated is also interesting from a clinical perspective.…”

“…OEC processes form conduits [61] that express a range of extracellular matrix proteins of which many are involved in cell adhesion [15,32,53]. One extracellular matrix protein has been shown to directly regulate the migration of OECs: the Ca 2+ -binding glycoprotein fibulin 3 [49]. Viral-mediated overexpression of fibulin 3 in OECs inhibited OEC migration and instead promoted OEC proliferation.…”

Increased migration of olfactory ensheathing cells secreting the Nogo receptor ectodomain over inhibitory substrates and lesioned spinal cord

“…Nevertheless, it has been demonstrated that in injured spinal cord, rat and human OECs migrate for shorter distances, in both rostral and caudal directions, compared to non-injured spinal cords [20]. At the molecular level, GDNF [21], Slit-2 [22,23], NogoA [24,25] and fibulin-3 [26] have been demonstrated to regulate OEC migration. In fact, we and others have demonstrated that the OEC migratory potential is largely impaired by myelin [24,25,27,28] and that this inhibition may be partially overcome by treatment with NEP1-40 peptide [24] or antibodies against the myelin receptor Nogo receptor [25].…”

Myelin-associated proteins block the migration of olfactory ensheathing cells: an in vitro study using single-cell tracking and traction force microscopy

“…5F). proliferation has recently been carried out on over glass surfaces with artificially generated gradients (Yan et al, 2003;Cao et al, 2006;Vukovic et al, 2009;Huang et al, 2011), in collagen scaffolds (Wang et al, 2006;Mollers et al, 2009), in nanofibers (Shen et al, 2010) and in biomaterial-coated substrates (Martin-Lopez et al, 2010b;Martin-Lopez et al, 2010a).…”