Molecular cloning and partial characterization of a low-density lipoprotein receptor-related protein 13 (Lrp13) involved in vitellogenin uptake in the cutthroat trout (Oncorhynchus clarki).
Multiple ovarian membrane proteins that bind vitellogenin (Vtg) have been detected in teleosts. One of these Vtg receptors was recently identified as low-density lipoprotein receptor-related protein 13 (lrp13/Lrp13) in perciform species, but little is known about this Vtg receptor in salmonid fish. In this study, a cDNA encoding a putative Vtg receptor with 13+1 ligand binding repeats (lr13+1) was cloned from the ovary, and identified as an lrp13 ortholog for cutthroat trout (Oncorhynchus clarki). This lrp13 was predominantly expressed in the pre-vitellogenic stage ovary, and its expression decreased during vitellogenesis. Ovarian localization of Lrp13 was observed by immunohistochemistry using specific antiserum against recombinant Lrp13. Lrp13 immunoreactivity was observed at the oolemma, throughout the zona radiata, and within the perivitelline space between the zona radiata and granulosa cells in ovarian follicles at both the lipid-droplet and vitellogenic stages of growth-an expression pattern that mimics that of a lr8/LR8-type Vtg receptor in this species and of lrp13/Lrp13 in Morone species. Six discrete Vtg-binding proteins were detected in cutthroat trout ovarian membrane proteins when probing with a digoxygenin-labeled salmonid A-type Vtg (VtgAs) followed by chemiluminescent ligand detection. Western blotting using the anti-Lrp13 serum revealed a broad signal consisting of two proteins with masses ranging from ∼190 to ∼210 kDa, which corresponded with some of the VtgA-binding proteins. These findings suggest that, in addition to lr8/LR8, lrp13/Lrp13 acts as a VtgA receptor in trout.
Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Japan.
Yuji
Y
Mushirobira
Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Japan.
Hiroko
H
Mizuta
Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Japan.
Wenshu
W
Luo
Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Japan.
Takashi
T
Todo
Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Japan.
Akihiko
A
Hara
Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina.
Benjamin J
BJ
Reading
Carolina AquaGyn, Raleigh, North Carolina.
Craig V
CV
Sullivan
Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Japan.
Naoshi
N
Hiramatsu
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D005260:Female; D029941:Fish Proteins / Q000096:biosynthesis / Q000235:genetics; D026502:LDL-Receptor Related Proteins / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D017683:Oncorhynchus / Q000235:genetics / Q000378:metabolism; D010053:Ovary / Q000166:cytology / Q000378:metabolism*; D014819:Vitellogenins / Q000235:genetics / Q000378:metabolism*
D029941:Fish Proteins; D026502:LDL-Receptor Related Proteins; D014819:Vitellogenins