Molecular characterization and expression analysis of the channel catfish cathepsin D genes

Tingting Feng, Hao Zhang, Hong Liu, Zunchun Zhou, Donghong Niu, Lilian Wong, Huseyin Kucuktas, Xiaolin Liu, Eric Peatman, Zhanjiang Liu

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Cathepsin D is a lysosomal aspartic proteinase that participates in various degradation functions of the cell. In this study, we characterized the cathepsin D genes in channel catfish and found two genes encoding catfish cathepsin D, referred to as cathepsin D1 and D2 genes. These two genes are highly similar in genomic structure and organization, sharing a moderate level of amino acid sequence similarity (56%). Genomic Southern analysis suggested the presence of a single copy of each of the cathepsin D1 and D2 genes. Phylogenetic analysis provided strong evidence that two cathepsin D genes are present in most of the teleost lineage, with cathepsin D2 likely having been lost in some higher vertebrate lineages. The catfish cathepsin D1 and D2 genes are expressed in virtually all the 11 tested tissues (brain, gill, heart, head kidney, trunk kidney, intestine, liver, muscle, skin, spleen, and stomach) on the transcript level, but appear to exhibit greater levels of expression in immune-related tissues and organs. Upon infection with Edwardsiella ictaluri, the expression of the catfish cathepsin D genes showed the most significant changes in liver and head kidney, with time points and magnitude of transcript changes varying between the two genes. We additionally examined bacterially-mediated changes of expression in gill, intestine, and trunk kidney. The fact that bacterial infection can induce expression of the cathepsin D genes and that they appeared to be expressed naturally at higher levels in immune-related organs may suggest that they are an important component of the innate immune response of catfish against bacterial infections.

Original languageEnglish (US)
Pages (from-to)164-169
Number of pages6
JournalFish and Shellfish Immunology
Issue number1
StatePublished - Jul 2011
Externally publishedYes


  • Antimicrobial
  • Catfish
  • Cathepsin D
  • Infection
  • Innate immunity

ASJC Scopus subject areas

  • Immunology and Microbiology (miscellaneous)
  • Aquatic Science
  • Immunology
  • Environmental Chemistry


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