MMP-9 deficiency affects axonal outgrowth, migration, and apoptosis in the developing cerebellum.
Matrix metalloproteinases (MMPs) are responsible for the extensive extracellular proteolysis that plays a central role in regulating the pericellular environment, contributing to morphogenesis and developmental remodeling. In the CNS, there is increasing in vitro evidence for the involvement of MMPs in neurite elongation and axonal guidance. Here, we show that expression of MMP-9 is spatiotemporally related to cerebellar granule cell migration during postnatal development. Using cerebellar explant cultures, we demonstrated that a specific MMP-9-blocking antibody affects granular cell axonal outgrowth and migration in a dose-dependent manner. In addition, the in vivo analysis of MMP-9-deficient mice revealed abnormal accumulation of granular precursors (GPs) in the external granular layer (EGL) at a time when migration is normally extensive. Furthermore, GP migration was delayed and their programmed cell death was reduced in MMP-9-deficient mice, suggesting that MMP-9 is involved in the control of granule cell migration and apoptosis. These results provide direct evidence for a physiological role of MMP-9 in neuronal precursor migration and apoptosis in the developing cerebellum, and emphasize the importance of MMP-9 in the temporal regulation of the cerebellar microenvironment.
Institut National de la Santé et de la Recherche Médicale U433, Neurobiologie Expérimentale et Physiopathologie, Faculté de Médecine Laennec, 69372 Lyon cedex 08, France.
Catherine
C
Vaillant
Claire
C
Meissirel
Mireille
M
Mutin
Marie-Françoise
MF
Belin
Leif R
LR
Lund
Nicole
N
Thomasset
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000502:physiology*; D001369:Axons / Q000201:enzymology / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D002531:Cerebellum / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout
D020780:Matrix Metalloproteinase 9