title: Identification and characterization of a cathepsin D homologue from lampreys (Lampetra japonica).
abstract: Cathepsin D (EC 3.4.23.5) is a lysosomal aspartic proteinase of the pepsin superfamily which participates in various digestive processes within the cell. In the present study, the full length cDNA of a novel cathepsin D homologue was cloned from the buccal glands of lampreys (Lampetra japonica) for the first time, including a 124-bp 5' terminal untranslated region (5'-UTR), a 1194-bp open reading frame encoding 397 amino acids, and a 472-bp 3'-UTR. Lamprey cathepsin D is composed of a signal peptide (Met 1-Ala 20), a propeptide domain (Leu 21-Ala 48) and a mature domain (Glu 76-Val 397), and has a conserved bilobal structure. Cathepsin D was widely distributed in the buccal glands, immune bodies, hearts, intestines, kidneys, livers, and gills of lampreys. After challenging with Escherichia coli or Staphylococcus aureus, the expression level of lamprey cathepsin D in the buccal gland was 8.5-fold or 6.5-fold higher than that in the PBS group. In addition, lamprey cathepsin D stimulated with Escherichia coli was also up-regulated in the hearts, kidneys, and intestines. As for the Staphylococcus aureus challenged group, the expression level of lamprey cathepsin D was found increased in the intestines. The above results revealed that lamprey cathepsin D may play key roles in immune response to exogenous pathogen and could serve as a potential antibacterial agent in the near future. In addition, lamprey cathepsin D was subcloned into pcDNA 3.1 vector and expressed in the human embryonic kidney 293 cells. The recombinant lamprey cathepsin D could degrade hemoglobin, fibrinogen, and serum albumin which are the major components in the blood, suggested that lamprey cathepsin D may also act as a digestive enzyme during the adaptation to a blood-feeding lifestyle.
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Xiao
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Zhilin
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Yinglun
authors.initials: Y
authors.lastname: Han
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Gou
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Bowen
authors.initials: B
authors.lastname: Li
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Duan
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Jihong
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: School of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China. Electronic address: liqw@263.net.
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002402:Cathepsin D / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000276:immunology / Q000502:physiology; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics* / Q000276:immunology; D054884:Host-Pathogen Interactions / Q000276:immunology; D007798:Lampreys / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013211:Staphylococcus aureus / Q000276:immunology / Q000502:physiology; D059467:Transcriptome / Q000235:genetics* / Q000276:immunology
chemical_list: D029941:Fish Proteins; D002402:Cathepsin D
keywords: Buccal gland; Cathepsin D; Immune defense; Lamprey