Identification of C-type natriuretic peptide in heart of spiny dogfish shark (Squalus acanthias).
An unidentified atrial natriuretic peptide (ANP)-like substance is the principal hormone regulating NaCl secretion in the shark rectal gland, an epithelial model tissue for hormone-sensitive secondary active chloride transport. Antibodies to mammalian ANP do not recognize the prohormone of marine species. The polymerase chain reaction (PCR) was used to isolate a partial cDNA encoding the shark heart natriuretic peptide. Using this partial sequence as a probe, the full-length clone [882 base pairs (bp)] was obtained from a shark heart cDNA library. Amino acids 119-135 are similar to the recently identified peptide sequences of porcine C-type natriuretic peptide (CNP) and killifish brain natriuretic peptide isolated from the brain of these species. Mature shark heart CNP terminates at the second cysteine residue and lacks a COOH-terminal extension, in contrast to cardiac ANP-like peptides of all other species. The primary amino acid sequence of the shark heart prepro-CNP is distinctly different from all other cardiac natriuretic peptides. Amplification of genomic DNA spanning the coding region produced a 1.5-kb product, indicating the presence of at least one intron. Sequencing confirmed the presence of two exons of 90 and 315 bp, separated by a 1.1-kb intron. This is the first report of a cDNA encoding in nonneuronal tissue. Elasmobranch CNP may represent a primordial form of ANP-like peptides that evolved as an adaptation to environmental osmoregulatory stress.
Medical Research Council, Molecular Genetics Unit, Cambridge, United Kingdom.
J P
JP
Schofield
D S
DS
Jones
J N
JN
Forrest
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D004284:Dogfish / Q000378:metabolism*; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D020098:Natriuretic Peptide, C-Type; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction
D009419:Nerve Tissue Proteins; D020098:Natriuretic Peptide, C-Type; D004247:DNA