The human endothelin family: three structurally and pharmacologically distinct isopeptides predicted by three separate genes.

Abstract

Three distinct human endothelin-related genes were cloned by screening a genomic DNA library under a low hybridization stringency with a synthetic oligonucleotide probe encoding a portion of the endothelin sequence. Genomic Southern blot analysis with the same oligonucleotide probe showed three corresponding chromosomal loci not only in the human genome but also in porcine and rat genomes. The nucleotide sequences of the three human genes were highly conserved within the regions encoding the 21-residue (mature) endothelins, in spite of the fact that the immediately upstream exon sequences, which encode a part of the propeptides, retained little similarity. Moreover, each of the human genes predicted a putative 21-residue peptide, similar to but distinct from each other: (i) the "classical" endothelin (ET-1), (ii) [Trp6,Leu7]endothelin (ET-2), and (iii) [Thr2,Phe4,Thr5,Tyr6, Lys7,Tyr'4]endothelin . Synthetic ET-1, ET-2, and ET-3 were prepared according to the deduced amino acid sequences, and the biological activities were assayed by contraction of isolated porcine coronary artery strips and by intravenous injection to anesthetized rats. All these synthetic peptides produced strong vasoconstrictor and pressor responses. However, the quantitative profiles of the pharmacological activities were considerably different among the three isopeptides, suggesting the possible existence of endothelin receptor subbpes.Endothelin is a potent vasoconstrictor/pressor peptide originally characterized from the culture supernatant of porcine aortic endothelial cells and consists of 21 amino acid residues with two sets of intrachain disulfide linkages (1). Sequence analysis of cloned cDNAs for porcine (1) and human (2) endothelin precursors showed that endothelin is produced in endothelial cells from an "200-residue prepropeptide much like many peptide hormones and neuropeptides. A presumptive 39-residue (porcine) or 38-residue (human) "big endothelin" is thought to be generated from the preproendothelin; the 21-residue (mature) endothelin is produced through an unusual proteolytic processing of big endothelin between Trp21 and Val22 residues. The amino acid sequences of mature porcine and human endothelin are identical. Preproendothelin mRNA has been detected not only in the cultured endothelial cells but also in porcine aortic endothelium in vivo, and the mRNA expression is markedly influenced by various chemical and mechanical stimuli to the endothelial cells (1, 10). These observations suggest an important role of endothelin in regulation of the mammalian cardiovascular system. In addition to the potent vasoconstrictor and pressor actions, endothelin has been reported to produce a wide spectrum ofbiological effects: regional vasodilatory effects in vivo (3); stimulation of proliferation of vascular smooth muscle cells and fibroblasts (4, 9); contraction of airway and intestinal smooth muscles (5, 6); positive inotropic and chronotropic effects on the myocardium (7, 8); release of icosanoids and/or endothelium-deri...

Drug Treatment of Hypertension: Focus on Vascular Health

“…NO may also be produced and released under the influence of stimuli such as acetylcholine, bradykinin, substance P, serotonin, and mechanical shear stresses 4 . The endothelium also produces endogenous vasoconstrictors, such as endothelin-1 (ET-1), which is particularly potent 4,14,15 . Human ET-1 is derived from pre-pro-ET-1 which is enzymatically cleaved to form big ET-1 which is further processed to form the active peptide by endothelin-converting enzyme 16 .…”

Presence of non‐selective type of endothelin receptor on vascular endothelium and its linkage to vasodilation

“…However, the precise mechanism is still ambiguous. Although it has been reported that the three ETs are almost equipotent in producing transient vasodilation [3,4], it was also…”

“…Sarafotoxins (SRTs), having chemical structures similar to those of ETs, also consist of a novel cardiotoxic peptide family [2] and these peptides interact witla ET receptors [1]. A diverse set of pharmacological activities with different potencies exerted by ET/SRT family peptides [3][4][5][6] suggested the existence of ET/SRT receptor subtypes. We have reported that two distinct subclasses of ET receptors, namely, ET-l-specific and ET/SRT family-common receptors, are distributed in various proportions in human and porcine tissues [7].…”

Ultraviolet B irradiation increases endothelin‐1 and endothelin receptor expression in cultured human keratinocytes

“…ET consists of three isopeptides, termed ET-1, ET-2 and ET-3 (ETs), while their receptors are classified, both pharmacologically and molecularly, into ET A and ETB subtypes [2][3][4][5]. The ET A receptor has different affinities for the three ET isoforms in the order of ET-I>ET-2>>ET-3.…”