Molecular and functional characteristics of APJ. Tissue distribution of mRNA and interaction with the endogenous ligand apelin.
We have recently identified apelin as the endogenous ligand for human APJ. In rats, the highest expression of APJ mRNA was detected in the lung, suggesting that APJ and its ligand play an important role in the pulmonary system. When apelin-36 and its pyroglutamylated C-terminal peptide, [<Glu(65)]apelin-13, were compared in microphysiometric analyses, the elevation of extracellular acidification induced in cells expressing APJ by [<Glu(65)]apelin-13 was transient, whereas that by apelin-36 was sustained. These responses were almost completely inhibited by a specific inhibitor for G(i) or that for Na(+)/H(+) exchanger. (125)I -Labeled [<Glu(65)]apelin-13 analogue specifically bound to APJ with a high affinity, and [<Glu(65)]apelin-13 was more potent than apelin-36 in competitive inhibition assays. Because pretreatment with apelin-36 but not [<Glu(65)]apelin-13 drastically reduced the binding of the labeled apelin to APJ, the different patterns of acidification induced by these two peptides appeared to reflect their dissociation rather than association with APJ. Apelin elicited the migration of APJ-expressing cells, and [<Glu(65)]apelin-13 was more potent than apelin-36 in this activity. Heterogeneous molecular forms of apelin corresponding to apelin-36 and [<Glu(65)]apelin-13 were produced in bovine colostrum. Apelin-36 and [<Glu(65)]apelin-13 might have different functions in vivo and in vitro.
Hosoya
M
M
Discovery Research Division, Takeda Chemical Industries Ltd., Wadai 10, Tsukuba, Ibaraki 300-4293, Japan.
Kawamata
Y
Y
Fukusumi
S
S
Fujii
R
R
Habata
Y
Y
Hinuma
S
S
Kitada
C
C
Honda
S
S
Kurokawa
T
T
Onda
H
H
Nishimura
O
O
Fujino
M
M
D000595:Amino Acid Sequence; D000818:Animals; D000073861:Apelin; D000075244:Apelin Receptors; D001921:Brain / Q000378:metabolism*; D016466:CHO Cells; D002352:Carrier Proteins / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D008024:Ligands; D008297:Male; D008969:Molecular Sequence Data; D009928:Organ Specificity; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
C115436:APLN protein, human; C104575:APLNR protein, human; D000073861:Apelin; D000075244:Apelin Receptors; C498579:Apln protein, rat; C491284:Aplnr protein, rat; D002352:Carrier Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D012333:RNA, Messenger; D017448:Receptors, Dopamine D2; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins; D010566:Virulence Factors, Bordetella