Widespread neuronal ectopia associated with secondary defects in cerebrocortical chondroitin sulfate proteoglycans and basal lamina in MARCKS-deficient mice.
Mice deficient in MARCKS, a prominent neural substrate for protein kinase C (PKC), die before or shortly after birth. They exhibit high frequencies of exencephaly, universal agenesis of forebrain commissures, and abnormalities of cerebral cortical and retinal lamination. We show here that these mice have wide-spread and severe neuronal ectopia in the outer layers of the developing forebrain, manifested by the migration of clusters of developing neuroblasts through the basal lamina and often through the pial membrane and into the subarachnoid space. This abnormality became apparent by Embryonic Day (E) 13 or 14, shortly after the formation of the early marginal zone. MARCKS deficiency was associated with decreased staining for marginal zone chondroitin sulfate proteoglycans; this decrease was detectable earlier in development than the neuronal ectopia. Later in development, there was also marked disruption of the basal lamina at the pial-glial interface, as evidenced by gross abnormalities in laminin and reticulin staining; however, the basal lamina appeared normal at E9.5. These data indicate that MARCKS is required for the prevention of neuronal ectopia during development. Potential mechanisms responsible for the neuronal ectopia in the MARCKS-deficient mice include decreased expression or increased proteolytic destruction of basal lamina proteins and marginal zone chondroitin sulfate proteoglycans in the developing brain.
Blackshear
P J
PJ
Department of Medicine, and the Sarah W. Stedman Center for Nutritional Studies, Duke University Medical Center, Durham, North Carolina 27710, USA.
Silver
J
J
Nairn
A C
AC
Sulik
K K
KK
Squier
M V
MV
Stumpo
D J
DJ
Tuttle
J S
JS
D000818:Animals; D000911:Antibodies, Monoclonal; D001485:Basement Membrane / Q000002:abnormalities / Q000737:chemistry / Q000166:cytology; D002540:Cerebral Cortex / Q000002:abnormalities* / Q000737:chemistry / Q000166:cytology*; D002809:Chondroitin Sulfates / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D007797:Laminin / Q000032:analysis / Q000276:immunology; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008817:Mice, Mutant Strains; D008855:Microscopy, Electron, Scanning; D009154:Mutation / Q000502:physiology; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009457:Neuroglia / Q000737:chemistry / Q000276:immunology; D009474:Neurons / Q000166:cytology*; D010841:Pia Mater / Q000002:abnormalities / Q000648:ultrastructure; D011247:Pregnancy; D011506:Proteins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D011509:Proteoglycans / Q000032:analysis / Q000235:genetics / Q000276:immunology; D012155:Reticulin / Q000032:analysis / Q000276:immunology; D016708:Synaptophysin / Q000235:genetics
D000911:Antibodies, Monoclonal; D047908:Intracellular Signaling Peptides and Proteins; D007797:Laminin; C000619711:Marcks protein, mouse; D008565:Membrane Proteins; D011506:Proteins; D011509:Proteoglycans; D012155:Reticulin; D016708:Synaptophysin; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D002809:Chondroitin Sulfates