Molecular characterization of rabbit phospholipid transfer protein: choroid plexus and ependyma synthesize high levels of phospholipid transfer protein.
Phospholipid transfer protein (PLTP) plays an important role in plasma lipoprotein metabolism. However, PLTP is expressed in a wide range of tissues suggesting additional local functions. To analyze the tissue distribution of PLTP in an animal with high-level expression of the structurally and functionally related CETP, we have cloned the full-length cDNA of rabbit PLTP (1,796 bp). Rabbit PLTP cDNA shows high homology to human, murine, and porcine PLTP cDNA, averaging 86.1%, 80.4%, and 86.1%, respectively. Interestingly, the C-terminus contains a unique seven amino acid insertion not found in previously characterized mammalian PLTPs. In clear contradistinction to human PLTP, rabbit PLTP mRNA was prominent in brain. In situ hybridization studies revealed specific, high-level synthesis of PLTP mRNA in choroid plexus and ependyma, the organs responsible for production of cerebrospinal fluid. Consistent with these findings, PLTP activity in cerebrospinal fluid amounted to 23% +/- 3% of that in rabbit plasma. In contrast, neither CETP mRNA nor CETP activity were detectable in rabbit brain.A role of PLTP in the central nervous system could involve some of its actions previously established in vitro, like proteolysis of apolipoproteins, and be physiologically relevant for neurodegenerative disorders such as Alzheimer's disease.
Gander
Roland
R
Department of Medicine, University of Innsbruck, Austria.
Eller
Philipp
P
Kaser
Susanne
S
Theurl
Igor
I
Walter
Doris
D
Sauper
Teresa
T
Ritsch
Andreas
A
Patsch
Josef R
JR
Föger
Bernhard
B
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D019556:COS Cells / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002522:Chlorocebus aethiops; D053480:Cholesterol Ester Transfer Proteins; D002788:Cholesterol Esters / Q000097:blood / Q000134:cerebrospinal fluid; D002831:Choroid Plexus / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004805:Ependyma / Q000378:metabolism*; D006023:Glycoproteins; D006801:Humans; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids / Q000097:blood / Q000134:cerebrospinal fluid; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D002788:Cholesterol Esters; D018076:DNA, Complementary; D006023:Glycoproteins; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids; D012333:RNA, Messenger