title: Mesencephalic trigeminal nucleus development is dependent on Krox-20 expression.
abstract: Krox-20, a C2H2-type zinc-finger transcription factor, plays an important role in rhombomere development. This study reveals that the Krox-20 null mutation impacts the development of mesencephalic trigeminal (Me5) neurons, a cell group traditionally thought to emerge from the mesencephalon. Based on cell counting studies, we show that Krox-20 null mutants have twice as many Me5 neurons relative to wildtypes at E15, but by birth have half the number of Me5 cells as wildtypes. TUNEL studies reveal a period of increased apoptosis from E17-P0 in mutants. The mutation does not result in differences in Me5 cell size, morphology, gene expression or peripheral projection patterns between genotypes, as demonstrated by retrograde tracing and Brn3a immunohistochemistry. The data suggest that Krox-20 regulates the period and extent of Me5 apoptosis, impacting the final number of Me5 neurons. The loss of Me5 in Krox-20-/- mice may highlight species-specific differences in the origin of these cells.
authors.affiliation: Center for Craniofacial Molecular Biology, School of Dentistry, Los Angeles, CA, USA.
authors.forename: Shampa
authors.initials: S
authors.lastname: De
authors.forename: Anh Quan
authors.initials: AQ
authors.lastname: Nguyen
authors.forename: Charles F
authors.initials: CF
authors.lastname: Shuler
authors.forename: Jack E
authors.initials: JE
authors.lastname: Turman
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002452:Cell Count; D048430:Cell Shape / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D051767:Early Growth Response Protein 2; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D007150:Immunohistochemistry; D008406:Masseter Muscle / Q000196:embryology / Q000294:innervation; D008636:Mesencephalon / Q000002:abnormalities* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation / Q000502:physiology; D009421:Nervous System Malformations / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009434:Neural Pathways / Q000002:abnormalities / Q000378:metabolism / Q000473:pathology; D050818:Transcription Factor Brn-3; D050819:Transcription Factor Brn-3A; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014278:Trigeminal Nuclei / Q000002:abnormalities* / Q000378:metabolism / Q000473:pathology
chemical_list: D004268:DNA-Binding Proteins; D051767:Early Growth Response Protein 2; C497327:Egr2 protein, mouse; C494189:Pou4f1 protein, mouse; D050818:Transcription Factor Brn-3; D050819:Transcription Factor Brn-3A; D014157:Transcription Factors