title: Twist2: role in corneal stromal keratocyte proliferation and corneal thickness.
abstract: OBJECTIVE
  Twist2 is a member of a family of bHLH transcription factors critical for normal mesenchymal proliferation and differentiation. In this study, the authors analyzed the role of Twist2 in the eye and cornea through examination of a Twist2 loss-of-function mouse mutant.
  
  
  METHODS
  Twist2 expression during eye development in the mouse was investigated using RT-PCR and mRNA slide in situ hybridization. Lineage tracing was performed using Cre reporter mice. Morphometric analyses were performed, and cell proliferation and cell death were investigated by immunohistochemistry using Ki67 and cleaved caspase 3 antibodies, respectively.
  
  
  RESULTS
  In the mouse, Twist2 is expressed first in the periocular mesenchyme and subsequently in the corneal stroma and endothelium of the developing eye. Loss of Twist2 function leads to corneal thinning and a reduced population of stromal keratocytes. The reduction in the stromal cell population can be traced back to embryonic stages during which the proliferation of stromal progenitor cells is impaired and to the reduced number of proliferating cells in the corneal limbus postnatally. Adult Twist2-null mice display enophthalmia and blepharophimosis. Corneal thinning in mutant mice is not accompanied by glaucoma, an association reported in human patients.
  
  
  CONCLUSIONS
  Twist2 is required for normal corneal keratocyte proliferation and eyelid morphogenesis in the mouse. Loss of Twist2 function leads to corneal thinning because of the reduction in stromal keratocyte proliferation.
authors.affiliation: Eye Genetics Research Group, Embryology, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, Sydney, NSW, Australia.
authors.forename: Linda
authors.initials: L
authors.lastname: Weaving
authors.forename: Marija
authors.initials: M
authors.lastname: Mihelec
authors.forename: Rebecca
authors.initials: R
authors.lastname: Storen
authors.forename: Drazen
authors.initials: D
authors.lastname: Sosic
authors.forename: John R
authors.initials: JR
authors.lastname: Grigg
authors.forename: Patrick P L
authors.initials: PP
authors.lastname: Tam
authors.forename: Robyn V
authors.initials: RV
authors.lastname: Jamieson
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D016569:Blepharophimosis / Q000235:genetics / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D003315:Cornea / Q000196:embryology* / Q000473:pathology*; D003319:Corneal Stroma / Q000196:embryology* / Q000378:metabolism; D015841:Enophthalmos / Q000235:genetics / Q000473:pathology; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D005838:Genotype; D018257:Helix-Loop-Helix Motifs / Q000502:physiology; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009024:Morphogenesis; D012333:RNA, Messenger / Q000235:genetics; D012097:Repressor Proteins / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051879:Twist-Related Protein 1 / Q000502:physiology*
chemical_list: D012333:RNA, Messenger; D012097:Repressor Proteins; D051879:Twist-Related Protein 1; C096852:Twist2 protein, mouse; D053148:Caspase 3