Chemistry and biosynthesis of pro-opiomelanocortin

Chrétien, Michel; Seidah, Nabil G.

doi:10.1007/bf02354864

Cited by 86 publications

(16 citation statements)

References 205 publications

(228 reference statements)

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“…In all cases, the sites of cleavage are represented by a pair of basic residues, most commonly Lys-Arg or Arg-Arg [1,4,5,8-l 11. This signal of pairs of basic residues required for proteolytic conversion has been originally observed for ,d-LPH to y-LPH conversion [12], and is now known to be common to most pro-hormone conversion processes [8,13,14].…”

Section: Introductionmentioning

confidence: 87%

“…The identity of the in vitro apomyoglobin as carrier [9,20]. The resultant maturation products was confirmed by microsethiazolinone residues at each sequenator cycle were quencing [1,5,8,11].…”

Section: Methodsmentioning

confidence: 99%

“…In the anterior lobe of the pituitary, POMC is converted into an N-terminal glycopeptide (NT) [1,5,9], a joining peptide (JP) [6], ACTH, &LPH and to a lesser extent into y-LPH, fl-endorphin and possibly&MSH [1,2,8]. In contrast, the major maturation products in the pars intermedia of the pituitary require a possible further maturation of the N-terminal * To whom reprint requests should be addressed glycopeptide [ 10,111, the production of cu-MSH and CLIP from ACTH and the formation of y-LPH and a collection of &endorphin-like peptides [l-3,7,8,11].…”

Section: Introductionmentioning

confidence: 99%

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Enzymatic cleavage of pro‐opiomelanocortin by anterior pituitary granules

et al. 1983

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This paper presents the results obtained when pig anterior pituitary granule lysates are incubated with rat pro-opiomelanocortin (POMC). The resultant peptides were analyzed by 3 systems of high-performance liquid chromatography. This approach, when coupled with microsequence analysis of the conversion products, allowed the unambiguous identification of a major chymotryptic-like activity (pH optimum around 8) associated with the granule lysates with a specificity directed towards selective Tyr-X and Phe-X bonds within the POMC molecule. Furthermore, these results also demonstrate that although the detected enzyme activity gives rise to products 'resembling' those expected, the characterization of the 'elusive' maturation enzyme responsible for the cleavage at pairs of basic residues remains to be critically evaluated. Pro-opiomelanocortinMaturation enzyme Specificity Pituitary granule High performance liquid chromatography Microsequence

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Section: Introductionmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enzymatic cleavage of pro‐opiomelanocortin by anterior pituitary granules

et al. 1983

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“…involved in the conversion of progesterone to cortisol (Chretien and Seidah, 1981). Consequently, also in the alleged endogenous production of prednisolone and possibly prednisone the adrenal origin can not be ruled out.…”

Section: Relationship Between Alleged Stress and The Recovery Of Tracmentioning

confidence: 99%

A field survey on the presence of prednisolone and prednisone in urine samples from untreated cows

Vincenti

Leporati

Capra

et al. 2012

Food Additives & Contaminants: Part A

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A field survey on the presence of prednisolone and prednisone in urine samples from untreated cows Prednisolone is a synthetic glucocorticoid widely employed in bovine clinical practice, which may be also illegally used as a growth promoter. Recent in vitro and in vivo studies lend support to the hypothesis that prednisolone could be synthesized from cortisol in untreated cattle subjected to stressful events. To verify such a hypothesis, a field survey was conducted on urine samples collected from 131 guaranteed untreated cows and analyzed for the presence of prednisolone and prednisone -in some instances also for cortisol and cortisone-with a validated HPLC/MS-MS method. None of the examined samples exhibited either prednisolone levels higher than the CC limit (around 0.70 g l -1 ) or prednisone, being therefore officially compliant for both analytes. Trace amounts of prednisolone, approximately estimated in the range 0.1-0.3 g l -1 , were found only in 7 samples from cows also showing urinary cortisol and cortisone levels higher than those detected in negative specimens, as the result of a probable stress condition. KEYWORDS:Prednisolone; cows; urine; cortisol, illicit growth promoters; liquid chromatography-tandem mass spectrometry Such modifications result in both an extended duration of GC therapeutical effects and a severalfold increase in their pharmacological potency, particularly in the anti-inflammatory action. These features, combined with the absence of a parallel increase of sodium-retaining effects, enhance the suitability of synthetic GCs for therapeutic purposes (Ferguson and Hoenig 1995). A number of commercial preparations containing different prednisolone esters are currently available for administration to cattle, covering a wide range of therapeutical applications, including primary ketosis, disorders of tendons and the musculoskeletal system, allergic reactions, skin diseases, and shock. In addition, prednisolone is included in a number of antibiotic preparations for intramammary administration, indicated for the treatment of cow mastitis (McDonald et al. 2007).Besides legal treatments, prednisolone and other GCs are frequently employed just before the animals are sold, to mask more or less severe pathologies, especially in the case of old cows at the end of their productive cycle. Another common law infringement is the administration of intramammary infusions without declaring nor applying an appropriate withdrawal time. In the last decade, synthetic GCs, including prednisolone, have been increasingly employed as illicit growth promoters in cattle (Stephany 2001;Cannizzo et al. 2011; European Commission 2012). When administered at low dosages for an extended period of time, GCs are known to significantly improve the feed conversion ratio, to increase the area of longissimus dorsi, one of the most valuable muscles in bovine meat breeds, and to enhance the overall carcass quality traits, yielding pale and tender meat ( apparently corroborated the conclusions drawn in the studies mentioned...

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“…In the rat AL, specific enzymatic cleavages of the precursor yield an aminoterminal glycopeptide of 74 amino acids (also referred to as 16K fragment), several forms of ACTH, and fl-LPH which is partially processed to fl-endorphin [9,11]. In the IL, POMC is processed more extensively: cleavage occurs at virtually all of the dibasic sites.…”

mentioning

confidence: 99%

Biosynthesis of pro-opiomelanocortin is increased in the rat intermediate pituitary following denervation

Seger

Kiss

Tol

et al. 1987

Neuroscience Letters

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In order to study the effect of pituitary intermediate lobe denervation on pro-opiomelanocortin (POMC) biosynthesis and processing, radioactive amino acids were incorporated in vitro into whole neurointermediate lobe (NIL) explants obtained from hypothalamic lesioned rats and control animals. The lesion in the basal hypothalamus removed the neural input to the intermediate pituitary and cut the neurohypophyseal neurons. One week after the lesion, approximately a 3-fold increase in the rate of synthesis of POMC peptides was found in the NIL. The content of POMC peptides was decreased. The results imply that denervation increases the rate of POMC synthesis and release, without altering the pattern of proteolytic processing.The pro-opiomelanocortin (POMC)-synthesizing cells in the anterior lobe (AL) and intermediate lobe (IL) of the pituitary gland differ in the regulation of POMC gene expression, biosynthesis and release as well as in the nature of the peptides formed. In the rat AL, specific enzymatic cleavages of the precursor yield an aminoterminal glycopeptide of 74 amino acids (also referred to as 16K fragment), several forms of ACTH, and fl-LPH which is partially processed to fl-endorphin [9,11]. In the IL, POMC is processed more extensively: cleavage occurs at virtually all of the dibasic sites. The smaller products formed in this tissue are a non-glycosylated 49-residue N-terminal fragment [3], [Lysl]yaMSH [5], ct-MSH and CLIP (ACTH1s_39) [6], 7-LPH and several forms of endorphins [16]. Furthermore, POMC is subject to many post-translational modifications, namely glycosylation and phosphorylation [6], as well as amidation [12], acetylation [14] and endoproteolytic cleavages [16] following the formation of the major products.

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Chemistry and biosynthesis of pro-opiomelanocortin

Cited by 86 publications

References 205 publications

Enzymatic cleavage of pro‐opiomelanocortin by anterior pituitary granules

Enzymatic cleavage of pro‐opiomelanocortin by anterior pituitary granules

A field survey on the presence of prednisolone and prednisone in urine samples from untreated cows

Biosynthesis of pro-opiomelanocortin is increased in the rat intermediate pituitary following denervation

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