Search Results

You are looking at 21 - 30 of 119 items for :

  • prohormone processing x
Clear All
Free access

AJ Stouthart, EC Lucassen, FJ van Strien, PH Balm, RA Lock and SE Wendelaar Bonga

Whole-body levels of ACTH, alpha-MSH and cortisol in eggs and larvae of the common carp (Cyprinus carpio) were determined periodically up until 168 h after fertilisation. ACTH, alpha-MSH and cortisol immunoreactivity was detected in unfertilised eggs, and endogenous production of ACTH and alpha-MSH was observed 24 h after fertilisation and that of cortisol 36 h after fertilisation. ACTH immunoreactivity reached peak levels before hatching (56-72 h after fertilisation) and remained relatively stable thereafter, while alpha-MSH immunoreactivity started to increase after hatching. At 36 h after fertilisation, whole-body cortisol levels increased rapidly reaching peak levels at the end of hatching (72 h after fertilisation), remaining stable until the end of the experiment. From 50 h after fertilisation onwards, embryos and larvae increased their whole-body cortisol levels when subjected to handling (mechanical pressure during egg stage or netting during the larval stage). It is concluded that the pituitary-interrenal axis in carp is fully functional at the time of hatching. No indications of a stress non-responsive period after hatching were observed. To characterise ACTH and alpha-MSH immunoreactivities in carp larvae, whole-body homogenates were analysed by HPLC, with pituitary homogenates of adult carp serving as a reference. ACTH and alpha-MSH immunoreactivity in carp larvae homogenates consisted of three and two products respectively. HPLC of adult carp pituitaries revealed the presence of two ACTH immunoreactive products, which may represent a phosphorylated and a non-phosphorylated ACTH variant, while the three alpha-MSH peaks most likely represent des-acetylated, mono-acetylated and di-acetylated alpha-MSH, the latter being the predominant form. In carp larvae, however, one of the ACTH immunoreactive products co-eluted with the non-phosphorylated ACTH, while the two alpha-MSH products identified co-eluted with des-acetylated and mono-acetylated alpha-MSH, indicating that POMC processing at this stage of development is different from prohormone processing in adult fish.

Free access

M Stridsberg, RH Angeletti and KB Helle

Chromogranin A (CgA) and chromogranin B (CgB) are acidic proteins stored in and released from hormone granules in endocrine and neuroendocrine tissue. The chromogranins are postulated to serve as pro-hormones to generate biologically active peptides, which may influence hormonal release and vascular functions or have antibacterial functions. Although N-terminal and C-terminal regions show some species amino acid homology, the chromogranins as a whole display considerable interspecies differences, which prevents their use in comparative studies of biological functions. We present four new radioimmunoassays for the measurement of defined N-terminal regions of CgA and CgB. A new radioimmunoassay for measurement of intact bovine CgA has also been developed. With these assays and two previously published ones, we have compared the cross-reactivity of chromogranins from man, cattle, sheep, goat, pig and horse and compared adrenomedullar content and serum levels of CgA from these species. We have also studied the influence of peptide concentrations and the ionic strength of the mobile phase on molecular weight estimations. Assays with antibodies directed against the N-terminal parts of CgA and CgB showed sufficient interspecies cross-reactivity to allow comparative quantification of the circulating levels in man, cattle, sheep, goat, pig and horse. Assays measuring the intact human or bovine CgA were not suitable for comparative purposes in samples from sheep, goat, pig and horse. Molecular interactions between vasostatin immunoreactive material and intact bovine CgA were demonstrated in gel permeation studies, suggesting that conclusions about the degree of N-terminal processing from elution profiles should be made with caution. Reliable interspecies comparison of chromogranins is difficult, but measurements with region-specific assays may be helpful to study concentrations of chromogranins and chromogranin-related peptides.

Free access

Sang-Nam Lee, Bonnie Peng, Roxane Desjardins, John E Pintar, Robert Day and Iris Lindberg

& Chronwall 1992 ). Thus, POMC expression is controlled differently in the two lobes of the pituitary. Previous data obtained using the PC2 and 7B2 null mouse models have shown that both nulls show defective prohormone processing in vivo ( Furuta et

Free access

François van Herp, Nick H M van Bakel, Anton J M Coenen, Kjell Sergeant, Bart Devreese and Gerard J M Martens

-background-adapted animals ( Jenks et al . 1993 ). The 37 kDa precursor form of POMC is processed to the intermediate N-terminal 18 kDa cleavage fragment and a number of peptides, including α-MSH. The prohormone convertase 2 (PC2) plays a primary role in the proteolytic

Free access

Kristien Vandenborne, Simon A Roelens, Veerle M Darras, Eduard R Kühn and Serge Van der Geyten

Processing of thyrotropin-releasing hormone prohormone (proTRH) generates a biologically active peptide, prepro-TRH-(160–169), which regulates TRH-induced thyrotropin secretion. PNAS 87 4439 –4443. Bulant M , Ladram A

Free access

Domenico Salvatore

- and time-dependent fashion. The primary mechanism of TH action involves the binding of 3,5,3′-triiodothyronine (T 3 ) to its nuclear receptors in the context of regulatory TH response elements in target genes. In humans, the thyroid produces the pro-hormone

Free access

Wenxia He, Xiangyan Dai, Xiaowen Chen, Jiangyan He and Zhan Yin

of various hormones, growth factors, cytokines, receptors, and molecules known to be involved in prohormone processing, such as gonadotropin-releasing hormone receptor 2 ( gnrhr2 ), androgen receptor ( ar ), progesterone receptor ( pgr ), estrogen

Free access

Carla Brancia, Paola Nicolussi, Pietro Cappai, Giorgio La Corte, Roberta Possenti and Gian-Luca Ferri

recognition of specific stretches of basic amino acid residues and their surrounding sequence/s. The best characterized prohormone processing enzymes acting on proVGF are PC1/3 and PC2 ( Trani et al. 2002 ). These are expressed in endocrine and

Free access

Tao Xie, Min Chen and Lee S Weinstein

anti-somatostatin (Lab Vision, Fremont, CA, USA), rabbit anti-prohormone convertase 1/3 (PC1/3), rabbit anti-PC2 (Millipore), or rabbit anti-G s α ( Simonds et al . 1989 ) antibodies, followed by secondary antibodies that were labeled with rhodamine or

Free access

Victor A Gault, David W Porter, Nigel Irwin and Peter R Flatt

) have highlighted potential differential posttranslational processing of GIP in gut K-cells. Thus, processing of the precursor protein pro-GIP by prohormone convertase 1/3 (PC1/3) is known to yield the full-length GIP(1–42) molecule ( Ugleholdt et al