Spatiotemporal activity of matrix metalloproteinase 2 (MMP) in the developing optic lobe

SANCHEZ, VN; DI GUILMI, MN; FUENTES, F; SCICOLONE, GE; RAPACIOLI, M; RIVAS, E; FLORES, VD

Guarujá, Brazil

Congreso; 2° international meeting of the latin american society of developmental biology; 2005

Cell surface molecules and the extracellular matrix (ECM) proteins are known to influence aspects of nervous system development, including cell proliferation, cell migration and neuritogenesis. Cell-ECM interactions provide essential information for controlling these processes. Matrix metalloproteinase (MMPs) constitute a large family of extracellular enzymes, which that participate in remodelling of pericellular environment, primarily though the cleavage of ECM proteins. In addition, MMPs are involved in the proteolytic processing of non-ECM receptors and ligands. MMP2 and MMP9 present gelatinolytic activity that is involved in tissue remodelling and development. In this work we investigate the pattern of gelatinases activity during the nervous system development using the chicken tectum opticum (TO) as model. The TO shows a cortical structure organized in alternating neuronal and fibrous laminae and plays and important role in the processing visual information. TOs from different embryonic ages (E) from E8 to newly hatched chicks (NH) were dissected. Tissue homogenates were ultracentrifuged to separate a soluble fraction (SN) and a pellet that was resuspended in buffer containing 0.5% Triton X-100 witch was ultracentrifuged to obtain a supernatant (E1). Both samples, SN and E1; were analysed. The MMP2 activity was determinate by SDS-PAGE gelatine zimography. Gelatinases present in the subcellular fractions degrade the gelatine matrix, leaving a clear band after staining the gel for protein. To determine the localization of MMPs activity in the TO, intramolecularly quenched gelatine (DQ gelatine) was used aas substrate for degradation by gelatinases in unfixed frozen tissue sections of this organ. We found that the MMP2 was the unique gelatinase detected in the developmental TO. Its pattern of activity exhibits a significant increase between E12 and E14. In situ activity was mainly detected in ventricular zone and neuronal layers. In Stratum Album Centrale was detected in cells located around the radial glia. Topographic and temporal pattern of gelatinolitic activity suggest that it`s related to cell migration in the TO laminar organization and this activity corresponds to MMP2. Supported by grants from UBACYT and CONICET. Argentina