Undetectable apolipoprotein A-I gene expression suggests an unusual mechanism of dietary lipid mobilisation in the intestine of Cyprinus carpio.
High density lipoprotein (HDL) has been shown to play an important role in the dietary lipid mobilisation in the carp. In spite of this, previous studies have failed to demonstrate the synthesis of the major protein component of HDL, apolipoprotein A-I (apoA-I), in the proximal intestine of the carp. Therefore, the aim of the present study was to evaluate the expression of apoA-I throughout the entire intestine. Curiously, no transcription of the apoA-I gene could be detected either by northern blot or RT-PCR assays in the intestinal mucosa, in clear contrast with the abundant cytosolic immunoreactive apoA-I detected in almost all intestinal segments, which suggests a different origin for this protein. In addition, the detection of specific, but low affinity, binding sites for apoA-I in the carp intestinal brush-border membranes (BBM), and the strong interaction with BBM, which is highly dependent on temperature, points to an important contribution of membrane lipids in apoA-I binding to the intestinal mucosa. This idea was reinforced by the ability of carp apoA-I to associate with multilamellar phospholipid vesicles.
Concha
Margarita I
MI
Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Campus Isla Teja, Valdivia, Chile.
López
Rodrigo
R
Villanueva
Julieta
J
Báez
Nadya
N
Amthauer
Rodolfo
R
D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism*; D015152:Blotting, Northern; D002347:Carps / Q000378:metabolism*; D017931:DNA Primers; D004041:Dietary Fats / Q000378:metabolism*; D004134:Dimyristoylphosphatidylcholine; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013053:Spectrophotometry
D016632:Apolipoprotein A-I; D017931:DNA Primers; D004041:Dietary Fats; D004134:Dimyristoylphosphatidylcholine