title: The Mohawk homeobox transcription factor regulates the differentiation of tendons and volar plates.
abstract: BACKGROUND
  Mohawk (Mkx) is a homeodomain-containing transcription factor that is expressed in various mesoderm-derived tissues, particularly in developing tendons. In this study, we investigate the exact expression pattern and functions of Mkx in forelimbs.
  
  
  METHODS
  We analyzed the forelimbs of Mkx knockout mice [from embryonic day (E) 18.5 to postnatal day (P) 28 weeks] by using knocked-in Venus signals, Masson trichrome staining, and hematoxylin and eosin (H&E) staining.
  
  
  RESULTS
  We detected Venus signals in forelimb tendons, pulleys, and volar plates (VPs) in P21 mice. In-depth histological analysis showed that compared to the wild-type mice, the Mkx knockout mice showed significant hypoplasia in the flexor digitorum profundus tendons from E18.5. The VPs and pulleys appeared normal until P0; however, by P14, they became increasingly thicker in Mkx-null mice compared to wild-type mice. The fiber alignment was particularly disrupted in VPs of Mkx-null mice.
  
  
  CONCLUSIONS
  These results suggest that Mkx is an important regulator of the differentiation of VPs and pulleys, as well as of tendon differentiation.
authors.affiliation: Department of Systems BioMedicine, National Center for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-0074, Japan, Nnok@aol.com.
authors.forename: Naoko
authors.initials: N
authors.lastname: Onizuka
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ito
authors.forename: Masayo
authors.initials: M
authors.lastname: Inagawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakahara
authors.forename: Shuji
authors.initials: S
authors.lastname: Takada
authors.forename: Martin
authors.initials: M
authors.lastname: Lotz
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Asahara
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation; D004195:Disease Models, Animal; D005552:Forelimb; D018507:Gene Expression Regulation, Developmental; D055786:Gene Knockout Techniques; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D009024:Morphogenesis / Q000235:genetics*; D053401:Palmar Plate / Q000254:growth & development* / Q000473:pathology; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics*; D013710:Tendons / Q000254:growth & development* / Q000473:pathology; D014158:Transcription, Genetic
chemical_list: D018398:Homeodomain Proteins; D012333:RNA, Messenger; C510657:mohawk protein, mouse