ZFIN ID: ZDB-PUB-061020-29
Phylogenetic relationships and gene expression pattern of three different cathepsin L (Ctsl) isoforms in zebrafish: Ctsla is the putative yolk processing enzyme
Tingaud-Sequeira, A., and Cerda, J.
Date: 2007
Source: Gene   386(1-2): 98-106 (Journal)
Registered Authors: Cerdà, Joan
Keywords: Killifish, Isoforms, Expression pattern, Yolk syncytial layer
MeSH Terms:
  • Amino Acid Sequence
  • Animals
  • Cathepsin L
  • Cathepsins/biosynthesis
  • Cathepsins/genetics*
  • Cathepsins/physiology
  • Cysteine Endopeptidases/biosynthesis
  • Cysteine Endopeptidases/genetics*
  • Cysteine Endopeptidases/physiology
  • Egg Yolk/chemistry
  • Egg Yolk/enzymology*
  • Evolution, Molecular
  • Fundulidae/genetics
  • Fundulidae/metabolism
  • Gene Expression Regulation/physiology*
  • Isoenzymes/biosynthesis
  • Isoenzymes/genetics
  • Molecular Sequence Data
  • Phylogeny*
  • Vitellogenesis
  • Zebrafish/genetics*
  • Zebrafish/metabolism*
  • Zebrafish Proteins/biosynthesis
  • Zebrafish Proteins/genetics*
  • Zebrafish Proteins/physiology
PubMed: 17027199 Full text @ Gene
Certain cysteine proteases, such as cathepsin L (Ctsl), have been involved in yolk processing mechanisms in oocytes and embryos of lower vertebrates. In zebrafish (Danio rerio), three different ctsl genes, ctsla, ctslb and ctslc, have been found in the genome, but their pattern of expression, as well as information on which the encoded enzymes are potentially involved in yolk absorption during embryogenesis, is unknown. Here, phylogenetic and gene structure analysis revealed that zebrafish ctsla and ctslb genes are similar, showing a highly conserved structure in comparison with human ctsl, while ctslc presents different exon organization together with an earlier evolution. Thus, ctslc appears to be evolved from a common ancestral ctsl-like gene, possibly through an early duplication event, whereas ctsla and ctslb may be originated from a second duplication mechanism. Zebrafish ctsla, ctslb and ctslc also showed different patterns of mRNA expression during embryogenesis and in adult tissues. While Ctsla transcripts were accumulated in embryos throughout development and in the adult ovary, those encoding Ctslb were detected only in embryos around the time of hatching as previously reported, and those for Ctslc appeared only in larvae and in some adult tissues, but not in the ovary. In zebrafish and killifish (Fundulus heteroclitus) embryos, Ctsla mRNA was first detected in blastomers, and later in development it was localized in cells of the yolk syncytial layer, an embryonic structure involved in yolk absorption. These data therefore suggested that Ctsla is most likely the putative protease involved in yolk processing in fish embryos, while Ctslc seems not to be required during early embryogenesis in zebrafish.