Metalloproteinase 2 (MMP-2) in the cell migration process during the chicken Optic Lobe development

DI GUILMI, MN; SANCHEZ, VN; GOMEZ, N; SCICOLONE, GE; RAPACIOLI, M; FLORES, VD

Atlanta, EE.UU.

Congreso; 36° annual meeting of Society for neuroscience; 2006

Society for Neuroscience (SFN)

Matrix metalloproteinases (MMPs) constitute a family of extracellular enzymes, which articipate in remodelling of pericellular environment through the cleavage of extracellular matrix (ECM) proteins. MMP-2 and MMP-9 present gelatinolytic activity that is involved in tissue remodelling and development. In this work we investigate the pattern of gelatinases activity in the developing optic lobe (OL). The OL shows a cortical structure organized in alternating neuronal and fibrous laminae. OLs from different embryonic ages (E) from E8 to newly hatched chicks (NH) were dissected. Tissue homogenates were ultracentrifugated to separate a soluble fraction (SN) and a pellet that was resuspended in buffer containing 0.5% Triton X-100 which was ultracentrifuged to obtain a new supernatant (E1). Both samples, SN and E1, were analysed. MMP-2 activity was determinate by SDS-PAGE gelatine zimography. Tissue localization of MMP-2 was detected by immunohistochemical assay in E12. The same method was used to study the subcellular localization of this enzyme by electron microscopy. To determine the localization of MMP-2 activity in the OL, intramolecularly quenched gelatine (DQ) was used as substrate of gelatinases in unfixed frozen tissue sections of this organ. We detected MMP-2 but not MMP-9 activity in the developing OL. The zimographic activity pattern exhibits a biphasic curve with a significant increase between E12 and E14 and an abrupt decrease was observed from E16 until NH in both fractions SN (p=0,0010) and E1 (p= 0,0021). The maximal activity was observed in E12. Tissue localization of MMP-2 was predominant in the cellular layers in comparison with the fibrous ones. High activity was detected in layers composed by cell populations that are migrating to constitute the definitive layers. The in situ activity was mainly detected in ventricular zone, in the neuronal layers and significant activity was detected in cells located around the radial glia. These results were supported by electron microscopy. Temporo-spatial patterns of MMP-2 expression and activity suggest that this MMP is related with the cell migration process in the OL lamination. This work was supported by grants from UBACYT and CONICET. Argentina.