Corticotropin-like Intermediate Peptide Research Articles

Biosynthesis of pairs of peptides related to melanotropin, corticotropin and endorphin in the pars intermedia of the amphibian pituitary gland.

This study concerns the biosynthesis of a number of peptides in the neurointermediate lobe of the pituitary gland of the aquatic toad, Xenopus laevis. Using pulse-chase incubations in vitro and high-performance liquid chromatographic analysis, it could be shown that these peptides are synthesized through processing of a prohormone, pro-opiomelanocortin; all peptides were released into the incubation medium. On the basis of electrophoretic analysis, selective amino acid incorporation and immunoprecipitation, as well as peptide mapping by high-performance liquid chromatography, the peptides were classified into three distinct groups: two related to melanocyte-stimulating hormone (melanotropin), two related to adrenocorticotropic hormone (corticotropin) and two endorphin-like peptides. Using tryptic and chymotryptic maps of synthetic alpha-melanotropin and des-Ac alpha N-alpha-melanotropin as references, one of the melanotropin-like peptides was identified as des-Ac alpha N-alpha-melanotropin; the other one represents neither alpha-melanotropin nor any other known melanotropic peptide. The two peptides that were immunologically related to corticotropin had characteristics consistent with a structures resembling a peptide previously named 'corticotropin-like intermediate lobe peptide', corticotropin-(18-39). The two endorphin-like peptides, although highly related, do not have the same primary structure. In view of the apparent structural differences between the two peptides in each group, the possible occurrence of two prohormones is discussed.

Occurrence of a new corticotropin-like intermediate lobe peptide in salmon pituitary glands

A new corticotropin-like intermediate lobe peptide (CLIP) has been identified in the pituitary of chum salmon, Oncorhynchus keta. The newly isolated peptide is a tetracosa peptide, which is two residues longer than the predominant form, CLIP I, with the following amino acid sequence, H-ArgProIleLysValTyrAlaSerSerLeuGlu GlyGlyAspSerSerGluGlyThrPheProLeuGlnAlaOH. This peptide, named CLIP II is the fourth line of evidence in the teleost that the pituitary gland secretes two different forms of processed hormones, for which precursor molecules are coded on two separate genes. Together with the structures of α-melanotropin I and II, two putative ACTH molecules are proposed.

Synthesis of the docosapeptide corresponding to the amino acid sequence of salmon corticotropin-like intermediate lobe peptide (CLIP).

The docosapeptide H-Arg-Pro-Val-Lys-Val-Tyr-Thr-Asn-Gly-Val-Glu-Glu-Gln-Ser-Ser-Glu-Gly-Phe-Pro-Ser-Glu-Met-OH, corresponding to the amino acid sequence of salmon corticotropin-like intermediate lobe peptide (CLIP), was synthesized, with the use of 1 M trifluoromethanesulfonic acid-thioanisole in trifluoroacetic acid as a deprotecting reagent.

The control of steroidogenesis by human fetal adrenal cells in tissue culture. IV. The effect of exposure to placental steroids.

The effect upon steroidogenesis of adding various steroids produced by the placenta was studied in short term cultures of human fetal adrenal cells. The addition of high concentrations (10(3) ng/ml) of estrone or estriol inhibited the production of cortisol, but only the former elicited a parallel increase in dehydroepiandrosterone (DHA) production. Estradiol was effective in inhibiting delta-4-3-ketosteroid production at concentrations of 10-100 ng/ml, levels which approach those found in the fetal circulation, while DHA production was increased at concentrations of 1 microgram/ml. The addition of progesterone (4 microgram/ml) to the medium caused increased production of cortisol and corticosterone, but had no effect on DHA production. Pregnenolone (4 microgram/ml) increased the basal production of DHA and slightly impaired both basal and ACTH-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect of estrogen is not influenced by other peptide hormones such as hCG, human prl, beta-lipotropin, corticotropin-like intermediate lobe peptide, or beta-endorphin. A revised model of the fetoplacental steroidogenic unit is presented which may explain both normal and fetal hyperplasia and postnatal involution of the adrenal cortex and the variations from this pattern seen in apituitary children.

Synthesis of the nonatriacontapeptide corresponding to the entire amino acid sequence of ostrich adrenocorticotropic hormone.

The nonatriaoontapeptide corresponding to the entire amino acid sequence of ostrich adrenocorticotropic hormone (ACTH) was synthesized by successive condensations of four peptide fragments ; Z (OMe)-(15-19)-OH, Z (OMe)-(11-14)-OH, Boc-(5-10)-OH and Z-(1-4)-NHNH2, with H-(20-39)-OBzl, a synthetic intermediate of ostrich-type corticotropin-like intermediate lobe peptide, followed by deprotection with 1M trifluoromethanesulfonic acid-thioanisole in TFA. The synthetic peptide exhibited an in vivo steroidogenic potency of 0.8 relative to synthetic human ACTH.

The control of steroidogenesis by human fetal adrenal cells in tissue culture. III. The effects of various hormonal peptides.

The effects upon production of cortisol and dehydroepiandrosterone (DHA) by human fetal adrenal cells in tissue culture were studied using commercial hCG (0.5 and 5 IU/ml), purified hCG (0.7-6.7 IU/ml), the alpha-subunit of hCG (200 and 1000 ng/ml), human GH (50 and 200 ng/ml), human PRL (0.1-100 ng/ml), alpha-MSH (0.1-10 ng/ml), corticotropin-like intermediate lobe peptide (200 ng/ml), human beta-lipotropin (0.1 and 0.2 ng/ml), and beta-endorphin (100 ng/ml). Although each peptide was added to the culture medium in a concentration either similar to that observed in the fetal circulation or (where such information was not available) in amounts several times greater than those effective for ACTH in this system, none demonstrated any significant stimulation of steroid production. In particular, repeated studies with hCG showed that this hormone had no stimulating effect upon DHA production, neither in cultures of whole adrenals nor in cultures of separated fetal zone and definitive zone cells. Furthermore, none of these peptides showed a synergistic effect upon DHA production when they were added to cultures together with concentrations of alpha-ACTH-(1-24) (10(2)-10(3) pg/ml) previously demonstrated to represent the middle of the dose-response curve. Indeed, the only significant interactions with alpha-ACTH-(1-24) observed in these studies were a slight reduction in cortisol production produced by corticotropin-like intermediate lobe peptide and apparent inhibition of DHA production by beta-lipotropin and GH. The data do not lend credence to the suggestion that any of these peptides plays an important role in vivo in stimulating fetal adrenal steroidogenesis.

ChemInform Abstract: SYNTHESIS OF THE DOCOSAPEPTIDE CORRESPONDING TO THE AMINO ACID SEQUENCE OF OSTRICH‐TYPE CORTICOTROPIN‐LIKE INTERMEDIATE LOBE PEPTIDE (CLIP)

Chemischer InformationsdienstVolume 12, Issue 39 Reviews ChemInform Abstract: SYNTHESIS OF THE DOCOSAPEPTIDE CORRESPONDING TO THE AMINO ACID SEQUENCE OF OSTRICH-TYPE CORTICOTROPIN-LIKE INTERMEDIATE LOBE PEPTIDE (CLIP) K. YASUMURA, K. YASUMURASearch for more papers by this authorK. OKAMOTO, K. OKAMOTOSearch for more papers by this authorS. SHIMAMURA, S. SHIMAMURASearch for more papers by this authorH. YAJIMA, H. YAJIMASearch for more papers by this author K. YASUMURA, K. YASUMURASearch for more papers by this authorK. OKAMOTO, K. OKAMOTOSearch for more papers by this authorS. SHIMAMURA, S. SHIMAMURASearch for more papers by this authorH. YAJIMA, H. YAJIMASearch for more papers by this author First published: September 29, 1981 https://doi.org/10.1002/chin.198139360AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue39September 29, 1981 RelatedInformation

Biosynthesis of phosphorylated forms of corticotropin-related peptides.

Phosphorylated forms of corticotropin[ACTH (1-39)], corticotropin-like intermediary lobe peptide[CLIP, ACTH (18-39)], and the common precursor for ACTH and beta-lipotropin (beta-LPH) have been identified in extracts of rat pituitaries, 32P-Labeled inorganic phosphate was successfully incorporated into ACTH (1-39), CLIP, and the ACTH/beta-LPH precursor in rat neurointermediary lobe explants and into ACTH (1-39) in isolated rat anterior pituitary cells. After peptidase digestion of the labeled CLIP and ACTH, the radioactive phosphate was recoverable as O-phosphoserine. The serine residue at position 31 was the only amino acid found to be phosphorylated in CLIP and ACTH (1-39). The unphosphorylated forms of both peptides were also synthesized. The demonstration of he incorporation of [32P]phosphate into CLIP, ACTH (1-39), and the ACTH/beta-LPH precursor is consistent with the hypothesis that, within the rat intermediary lobe, phosphorylated CLIP is derived from a phosphorylated form of the common precursor, with phosphorylated ACTH (1-39) acting as a biosynthetic intermediate.

Isolation and characterization of corticotropin- and melanotropin-related peptides from the neurointermediary lobe of the rat pituitary by reversed-phase liquid chromatography.

A novel procedure utilizing reversed-phase high-performance liquid chromatography for the extraction and purification of peptides from biological tissues has been applied to the isolation of corticotropin-like intermediary lobe peptide (CLIP) and alpha-melanocyte-stimulating hormone (alpha-MSH) from the neurointermediary lobe of the rat pituitary. The isolation and characterization of two major forms of CLIP and two major forms of alpha-MSH are described. The isolated peptides have been identified by using enzymatic digestions and peptide mapping. The main form of ClIP is a peptide which has been modified by phosphorylation of the serine residue at position 31. This is the first peptide of endocrine origin reported to be modified in such a manner. A non-phosphorylated form of CLIP was also present at lower concentrations. The main form of alpha-MSH was found to be N,-O-diacetyl-alpha-MSH, with the more familiar mono-N-acetyl-alpha-MSH present to a much smaller extent. Thus, in the rat neurointermediary lobe, the two main corticotropin-related peptides present are mostly in modified forms which are the result of posttranslational modifications. It is only by the use of methodology such as that described in this paper that small alterations in peptide structure may be identified.

Natural occurrence but lack of melanotrophic activity of gamma-MSH in fish.

When adrenocorticotropin (ACTH) and β-lipotropin (LPH) are enzymatically cleaved in the pituitary from their common precursor molecule, a glycopeptide with an apparent molecular weight of 16,000 remains (reviewed in ref. 1). Sequencing of a cDNA copy of the bovine pituitary mRNA for the precursor molecule demonstrated that, within the region encoding the 16,000-moIecular weight (MW) glycopeptide, there was a short sequence homologous with the α-melanocyte-stimulating hormone (α-MSH) contained in ACTH and the β-MSH within β-LPH2. It was therefore proposed that the region of homology coded for a γ-MSH which might have biological activity, although synthetic peptides containing this sequence were shown to have poor melanotrophic activity3. In the pars intermedia further rapid enzyme modification converts ACTH to α-MSH and corticotropin-like intermediate lobe peptide (CLIP), and β-LPH to β-MSH and β-endorphin. Although smaller peptides containing the γ-MSH structure have been detected in extracts of the bovine pars intermedia4,5, the major post-translational products of the 16,000-MW fragment are present mainly as large glycosylated peptides1,4. We report here that a major peptide product of the neurointermediate lobe of the dogfish pituitary which we had previously shown to lack melanotrophic activity has a γ-MSH-like structure. Therefore if γ-MSH is a peptide with a function it is not one shared with the melanotrophic hormones.

Pars intermedia peptides: studies in adult humans.

A combination of radioimmunoassays and chromatography under acid-dissociating conditions has been used to obtain profiles of ACTH and LPH-related peptides in human plasma and cerebrospinal fluid. The spectra of peptides observed in these two fluids differ markedly. ACTH, beta-LPH, gamma-LPH and beta-endorphin are observed in the plasma of normal subjects and patients with increased pituitary ACTH secretion, whereas cerebrospinal fluid contains ACTH, beta-LPH, gamma-LPH and beta-endorphin, a 31 000-molecular-weight putative precursor having ACTH, LPH and gamma-MSH immunoreactivities, as well as pro-gamma-MSH(1-77) and smaller immunoreactive gamma-MSH fragments, alpha-MSH was not observed in blood or cerebrospinal fluid but this pars intermedia peptide and corticotropin-like intermediate lobe peptide (CLIP) were both found in tumour tissues obtained from patients with the ectopic ACTH syndrome. In vitro studies of human pituitary tumour tissues confirmed concomitant secretion of ACTH, beta-LPH, gamma-LPH, beta-endorphin and pro-gamma-MSH, which could be stimulated by a preparation of crude stalk median eminence and synthetic arginine vasopressin, from the rat, and could be suppressed by hydrocortisone. Clinical studies in which electroacupuncture was used to alleviate the symptoms of heroin withdrawal or recurrent pain revealed that concentrations of met-enkephalin and beta-endorphin, respectively, may rise in cerebrospinal fluid in association with relief of symptoms.

Synthesis of the docosapeptide corresponding to the amino acid sequence of ostrich-type corticotropin-like intermediate lobe peptide (CLIP).

The docosapeptide, H-Arg-Pro-Val-Lys-Val-Tyr-Pro-Asn-Gly-Val-Gln-Glu-Glu-Thr-Ser-Glu-Gly-Phe-Pro-Leu-Glu-Phe-OH, corresponding to positions 18 to 39 of ostrich ACTH (ostrich-type corticotropin-like intermediate lobe peptide, ost-CLIP), was synthesized, using 1M trifluoromethanesulfonic acid-thioanisole in TFA as a deprotecting reagent.

The protein-coding sequence of the bovine ACTH-beta-LPH precursor gene is split near the signal peptide region.

The pituitary hormones corticotropin (ACTH) and beta-lipotropin (beta-LPH) are formed from a large common precursor. Recently, we have elucidated the whole primary structure of the bovine ACTH-beta-LPH precursor (designated alternatively as preproopiocortin) by determining the nucleotide sequence of cloned DNA complementary to the mRNA coding for the precursor protein. The amino acid sequence assigned has disclosed a characteristic repetitive structure of the ACTH-beta-LPH precursor. The repetitive units of the precursor protein each contain a melanotropin (MSH) sequence (alpha-, beta- or gamma-MSH) as well as other peptide components such as beta-endorphin and corticotropin-like intermediate lobe peptide (CLIP). The repetitive units as well as their peptide components are each bounded by paired basic amino acid residues, which apparently represent the sites of proteolytic processing. Several studies have confirmed the translational initiation site and protein structure assigned (see also ref. 11 and refs therein). In view of the recent knowledge about the organization of eukaryotic genes (see refs 12, 13 for reviews), it would be of particular interest to investigate the relationship between the repetitive structure of the ACTH-beta-LPH precursor containing different functional components and the arrangement of the protein-coding sequence in its gene. We have now isolated and characterized bovine genomic DNA fragments encoding this precursor protein and have demonstrated that the protein sequence is encoded by two non-consecutive DNA segments. An intron (intervening sequence) of approximately 2.2 kilobase pairs separates the smaller exon (mRNA-coding sequence), which contains the gene sequence encoding the signal peptide, from the larger exon, which contains the gene sequence for most of the protein structure, including the known biologically active component peptides.

Isolation of ACTH 1–39, ACTH 1–38 and clip from the calf anterior pituitary

Calf anterior pituitaries were defatted and homogenized and peptides were adsorbed from the homogenate supernatant onto octadecylsilyl-silica. After elution, the resulting extract was subjected to gradient elution reversed-phase high pressure liquid chromatography (RP-HPLC) using aqueous acetonitrile containing 0.1% ( v v ) trifluoroacetic acid (TFA). Radioimmunoassay of column fractions for corticotropin (ACTH) revealed three major areas of immunoreactivity. Each was purified to homogeneity by gradient elution RP-HPLC employing aqueous acetonitrile containing either 0.13% heptafluorobutyric acid ( v v ) or 0.1% TFA ( v v ). Amino acid analysis and exopeptidase and trypsin digestions revealed the three forms of corticotropin to be ACTH 1–38, corticotropin-like intermediary lobe peptide, (CLIP, ACTH 18–39) and ACTH 1–39. 3H-labeled ACTH 1–39 did not give rise to either 3H-ACTH 1–38 or 3H-CLIP during isolation.

Alternative synthesis of corticotropin-like intermediate lobe peptide (human CLIP). A peptide corresponding to the sequence of human ACTH-(18--39).

A novel synthesis of human CLIP, a peptide corresponding to the sequence of human ACTH-(18-39) is described. The dodecapeptide chain was assembled by a combination of fragment condensation and stepwise synthesis while using N alpha-benzyloxycarbonyl and side chain tert.-butyl-derived protective groups combination. The final deprotection was performed by acidolysis in trifluoroacetic acid. The end product was purified by ion exchange chromatography on carboxymethyl cellulose.

Structure and biosynthesis of pro-adrenocorticotropin/endorphin and related peptides.

THIS REVIEW will deal with the biosynthesis of many of the members of the ACTH/lipotropin (LPH) family of peptides (Fig. 1). Peptides in this family fall into two groups: peptides related to ACTH include α-melanotropin (αMSH) and corticotropin-like intermediate lobe peptide (CLIP); peptides related to βLPH include γLPH, βMSH, and β-endorphin. In several species ACTH and βLPH each contain an identical heptapeptide segment located in the region of the molecule that is responsible for melanotropic bioactivity (1, 2). In this review we have taken a somewhat historical approach, and will therefore begin with a discussion of the biosynthesis of ACTH and the characterization of biosynthetic precursors to ACTH. When this work began, βLPH, γLPH, and βMSH were well-characterized pituitary peptides, but the opioid peptides (and β-endorphin in particular) had not yet been identified (3–5). Studies on the biosynthesis of ACTH were heavily influenced by prior work defining the biosynthetic pathways for insulin and para...

Biosynthesis and characterization of adrenocorticotropic hormone, alpha-melanocyte-stimulating hormone, and an NH2-terminal fragment of the adrenocorticotropic hormone/beta-lipotropin precursor from rat pars intermedia.

Isolated intermediate lobe cells from 40 rat pituitaries were incubated for 3 h with [35S]methionine + [3H]-phenylalanine, [35S]methionine, [3H]valine, and [3H]leucine. The cell extracts were purified by carboxymethyl-cellulose chromatography (CMC) and the fraction eluting with ovine adrenocorticotropic hormone (ACTH) was further purified either by another CMC under the same conditions or by high performance liquid chromatography (HPLC). Microsequencing of the product from the second CMC allowed the identification of a peptide containing methionine 4 and phenylalanine 7, as expected for the NH2 terminus of ACTH. Purification by HPLC of a similar peptide obtained from the three other incubations gave three main raoactive peaks which were further characterized by their migration rates on polyacrylamide gels, molecular weight, and microsequencing. Results indicated that intact ACTH (residues 1-39) is present in extracts of rat intermediate lobe, but in very small quantities (less than 1% of the beta-endorphin content). ACTH is probably broken down into smaller fragments, e.g. alpha-melanocyte-stimulating hormone (alpha-MSH) (ACTH, 1-13) and corticotropin-like intermediate lobe peptide (CLIP) (ACTH, 18-39). These studies also revealed with existence of a peptide having identical sequence with the (N-1) terminus of the ACTH/lipotropin (LPH) precursor.

Synthesis and secretion of corticotropins, melanotropins, and endorphins by rat intermediate pituitary cells.

The synthesis and secretion of various intermediate pituitary proteins was studied by using dispersed intermediate pituitary cell suspensions. Control studies indicated that the isolated cells were obtained in good yield and that after more than 24 h in culture the isolated cells continued to synthesize a collection of proteins similar to those found in freshly extracted intermediate pituitary tissue. Rat intermediate pituitary cells synthesized a molecule (Mr = 30,000; called 30K) that contained antigenic determinants for beta-endorphin, gamma-lipotropin, corticotropin (ACTH), and 16K fragment (the NH2-terminal region of mouse tumor cell pro-ACTH/endorphin). This 30K molecule, two high molecular weight forms of ACTH(13K and 20K), and 16K fragment were all shown to be glycoproteins. Continuous labeling and pulse-chase incubations were used to define the intracellular biosynthetic processing of the 30K molecule. After a 15-min pulse incubation the 30K molecule was the only labeled protein containing antigenic determinants for beta-endorphin, gamma-lipotropin, ACTH, or 16K fragment. A beta-lipotropin-like molecule served as a biosynthetic intermediate in the production of proteins similar to beta-endorphin and gamma-lipotropin. Methionine-enkephalin and alpha-endorphin were not major products in the intermediate lobe cells. Molecules similar to alpha-melanocyte-stimulating hormone and corticotropin-like intermediate lobe peptide (ACTH(18-39)) were also derived from the same 30K molecule; 20K ACTH served as a biosynthetic intermediate in this conversion. In rat intermediate pituitary cells ACTH(1-39) was not a major final product of the intracellular biosynthetic processing of the 30K molecule. The 30K molecule also served as a precursor to a protein similar to mouse tumor cell 16K fragment and related smaller proteins. With rat intermediate pituitary cells, pulse-chase experiments utilizing [35S]methionine demonstrated almost quantitative conversion of the 30K precursor into labeled proteins similar to beta-endorphin and alpha-melanocyte-stimulating hormone. In the absence of added secretagogues, small amounts of all of the smaller proteins derived from the 30K precursor were secreted coordinately into the culture medium.

Synthesis of the nonatriacontapeptide corresponding to the entire amino acid sequence of dogfish adrenocorticotropic hormone (Squalus acantias).

The nonatriacontapeptide corresponding to the entrie amino acid sequence of dogfish adrenocorticotropic hormone was synthesized by successive condensations of three peptide fragments ; Z (OMe)-(15-19)-OH, Z (OMe)-(11-14)-NHNH2 and Z-(1-10)-OH, with H-(20-39)-OBzl, a synthetic intermediate of dogfish corticotropin-like intermediate lobe peptide. The synthetic peptide exhibited the in vivo steroidogenetic activity of 21.3 IU/mg.

Synthesis of the docosapeptide corresponding to the entire amino acid sequence of dogfish corticotropin-like intermediate lobe peptide.

The docosapeptide, H-Arg-Pro-Ile-Lys-Val-Tyr-Pro-Asn-Ser-Phe-Glu-Asp-Glu-Ser-Val-Glu-Asn-Met-Gly-Pro-Glu-Leu-OH, corresponding to dogfish corticotropin-like intermediate lobe peptide (CLIP), was synthesized using protecting groups removable by hydrogen fluoride.