Experimental Sey mouse chimeras reveal the developmental deficiencies of Pax6-null granule cells in the postnatal cerebellum.
Pax6 has been implicated in cerebellar granule cell development, however the neonatal lethality of the Sey/Sey mutant has precluded a more detailed study of this late developing neuronal type. In this study we use experimental mouse chimeras made from wildtype and Pax6-null embryos to circumvent early lethality and assess the developmental potential of mutant cells in the construction of the cerebellum. We have identified the granule cell as a direct target of mutant gene action, with glia and Purkinje cells being affected in what is largely a non-cell autonomous manner. Most dramatically, in postnatal day 21 (P21) chimeras, mutant cells are largely absent in the anterior and posterior cerebellum while present in central lobules, but amidst disorganized cerebellar architecture. Analysis of P0/1 and P10 chimeras demonstrates a profound temporally based defect where mutant cells colonize the anterior and posterior EGL but fail to migrate to the IGL. Mutant granule cells in the central lobules can reach the IGL in an abnormal manner, with large streams of cells forming raphes through the molecular layer. These studies provide new insights into the role of Pax6 in postnatal cerebellar development that pinpoint the granule cell as an intrinsic target of the mutant gene and key events in the life of the developing granule cell that depend upon normal Pax6 expression.
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, 950 West 28th Ave, Vancouver, Canada BC V5Z 4H4. djswan@cmmt.ubc.ca
Douglas J
DJ
Swanson
Dan
D
Goldowitz
D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation; D002465:Cell Movement; D002531:Cerebellum / Q000254:growth & development* / Q000473:pathology; D002678:Chimera; D005136:Eye Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D005260:Female; D018398:Homeodomain Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D019394:Ki-67 Antigen / Q000032:analysis; D051379:Mice; D008807:Mice, Inbred BALB C; D008813:Mice, Inbred ICR; D008818:Mice, Neurologic Mutants; D009474:Neurons / Q000166:cytology; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D012097:Repressor Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*
D005136:Eye Proteins; D018398:Homeodomain Proteins; D019394:Ki-67 Antigen; C498355:Mki67 protein, mouse; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D012097:Repressor Proteins