title: Zebrafish transforming growth factor-β-stimulated clone 22 domain 3 (TSC22D3) plays critical roles in Bmp-dependent dorsoventral patterning via two deubiquitylating enzymes Usp15 and Otud4.
abstract: BACKGROUND
  Osmotic stress transcription factor 1/transforming growth factor-β-stimulated clone 22 domain 3 (Ostf1/Tsc22d3) is a transcription factor that plays an osmoregulatory role in euryhaline fishes. Its mRNA and protein levels are up-regulated under hyperosmotic stress. However, its osmoregulatory and developmental functions have not been studied in any stenohaline freshwater fishes. Zebrafish is an excellent model to perform such study to unfold the functional role of Tsc22d3.
  
  
  METHODS
  We identified the zebrafish Tsc22d3 and performed knockdown studies using morpholino antisense oligonucleotide (MO).
  
  
  RESULTS
  Zebrafish Tsc22d3 did not response to hypertonic stress and ts22d3 knockdown or overexpression by injecting MO or capped RNA did not change the transcriptional levels of any of the known ionocyte markers. To reveal the unknown function of zebrafish Tsc22d3, we performed several in situ molecular marker studies on tsc22d3 morphants and found that Tsc22d3 plays multi-functional roles in dorsoventral (DV) patterning, segmentation, and brain development. We then aimed to identify the mechanism of Tsc22d3 in the earliest stages of DV patterning. Our results demonstrated that tsc22d3 is a ventralizing gene that can stimulate the transcription of bone morphogenetic protein 4 (bmp4) and, thus, has a positive effect on the Bmp signaling pathway. Furthermore, we showed that Tsc22d3 interacts with deubiquitylating enzymes, ubiquitin-specific protease 15 (Usp15) and ovarian tumor domain containing protein 4 (Otud4). In addition, the interruption of Bmp4 signaling by double knockdown of usp15 and otud4 reduced the ventralized effects in tsc22d3-overexpressing embryos.
  
  
  CONCLUSIONS
  This is the first study to identify new developmental functions of Tsc22d3 in zebrafish.
  
  
  CONCLUSIONS
  Zebrafish tsc22d3 is a ventralizing gene and plays a role in early embryogenesis.
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong. kftse@hkbu.edu.hk
authors.forename: William Ka Fai
authors.initials: WK
authors.lastname: Tse
authors.forename: Yun-Jin
authors.initials: YJ
authors.lastname: Jiang
authors.forename: Chris Kong Chu
authors.initials: CK
authors.lastname: Wong
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019521:Body Patterning; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D017931:DNA Primers; D055785:Gene Knockdown Techniques; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000737:chemistry / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology; D029961:Zebrafish Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D019485:Bone Morphogenetic Proteins; D017931:DNA Primers; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D029961:Zebrafish Proteins
keywords: Embryogenesis; Osmoregulation; Osmotic stress transcription factor 1