CRH-BP: the regulation and function of a phylogenetically conserved binding protein

Westphal, Nicole J.; Seasholtz, Audrey F.

doi:10.2741/1931

Cited by 115 publications

(107 citation statements)

References 110 publications

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“…Hypothalamic CRHBP binds CRH (and uts1) with a higher affinity than the type 1 crh receptor, which reduces the bioavailability of CRH and, subsequently, the CRH-induced release of pituitary ACTH (Potter et al 1991, Cortright et al 1995, Westphal & Seasholtz 2006. Also in carp CRHBP appears to be a functional modulator of hypophysiotropic CRH, since the expression of preoptic area crhbp mRNA is elevated upon a 24 h restraint stressor and CRHBP is colocalized in CRH immunoreactive neurons projecting from the hypothalamus to pituitary corticotropes .…”

Section: Discussionmentioning

confidence: 99%

Central and peripheral integration of interrenal and thyroid axes signals in common carp (Cyprinus carpio L.)

Geven

Flik²,

Klaren

2008

Journal of Endocrinology

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In teleostean fishes the hypothalamic-pituitary-thyroid axis (HPTaxis) and the hypothalamic-pituitary-interrenal axis (HPI axis) regulate the release of thyroid hormones (THs) and cortisol respectively. Since many actions of both hormones are involved in the regulation of metabolic processes, communication between both signal pathways can be anticipated. In this study, we describe central and peripheral sites for direct interaction between mediators of both neuroendocrine axes in the common carp (Cyprinus carpio). Despite suggestions in the literature that CRH is thyrotropic in some fish; we were not able to establish stimulatory effects of CRH on the expression of the pituitary TSHb subunit gene. In preoptic area tissue incubated with 10 K7 M thyroxine (T 4 ) a 2 . 9-fold increase in the expression of CRH-binding protein (CRHBP) was observed. Thus, T 4 could reduce the bioavailable hypothalamic crh via the up regulation of crhbp expression and hence down regulate the HPI axis. At the peripheral level, cortisol (10 K6 M), ACTH (10 K7 M), and a-MSH (10 K7 M) stimulate the release of T 4 from kidney and head kidney fragments, which contain all functional thyroid follicles in carp, by two-to fourfold. The substantiation of three pituitary thyrotropic factors, viz. TSH, ACTH, and a-MSH, in common carp, allows for an integration of central thyrotropic signals. Clearly, two sites for interaction between the HPT axis, the HPI axis, and a-MSH are present in common carp. These interactions may be key to the proper regulation of general metabolism in this fish.

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Section: Discussionmentioning

confidence: 99%

Central and peripheral integration of interrenal and thyroid axes signals in common carp (Cyprinus carpio L.)

Geven

Flik²,

Klaren

2008

Journal of Endocrinology

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“…The effects of CRF and CRF-like peptides are mediated via two receptor subtypes, the CRF type 1 (CRF-R1) and CRF type 2 (CRF-R2) receptors. Both receptors are expressed in a variety of locations in the brain and body where they act to maintain homeostatic balance in response to stress (Bale and Vale, 2004) Another regulator of CRF, corticotropin-releasing factor binding protein (CRFBP), has been shown to modulate the effects of CRF or CRF-related ligands in both the central nervous system and in peripheral tissue (Potter et al, 1992;Behan et al, 1993;Seasholtz et al, 2002;Bale and Vale, 2004;Huising et al, 2005;Westphal and Seasholtz, 2006). CRFBP decreases cortisol release by inhibiting the effects of CRF (Behan et al, 1995;Chan et al, 2000) and regulates ACTH release by blocking CRF in the pituitary (Westphal and Seasholtz, 2006).This effect of CRFBP on cortisol levels implies that there is a direct link between CRF and cortisol.…”

Section: Introductionmentioning

confidence: 99%

Sequences, expression patterns and regulation of the corticotropin-releasing factor system in a teleost

Chen

Fernald

2008

General and Comparative Endocrinology

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Corticotropin-releasing factor (CRF) is well known for its role in regulating the stress response in vertebrate species by controlling release of glucocorticoids. CRF also influences other physiological processes via two distinct CRF receptors (CRF-Rs) and is co-regulated by a CRF binding protein (CRFBP). Although CRF was first discovered in mammals, it is important for the regulation of the stress response, motor behavior, and appetite in all vertebrates. However, it is unclear how the actions of CRF, CRF-Rs and CRFBP are coordinated. To approach this problem, we cloned and identified CRF, CRF-Rs and CRFBP in a teleost fish model system, Astatotilapia burtoni and mapped their expression patterns in the body and brain. We found that CRF, CRFBP and CRF-Rs gene sequences are highly conserved across vertebrates, suggesting that the CRF system plays an essential role in survival. Members of the CRF system are expressed widely in the brain, retina, gill, spleen, muscle and kidney, thereby implicating them in a variety of bodily functions, including vision, respiration, digestion and movement. We also found that following long-term social stress, mRNA expression of CRF in the brain and CRF type 1 receptor in the pituitary decrease whereas CRFBP in the pituitary increases via a homeostatic mechanism.

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“…The primary action of CRH-BP is generally thought to be inhibitory on the CRH-induced ACTH release from pituitary corticotropes (Potter et al 1991, Cortright et al 1995, Westphal & Seasholtz 2006. In common carp, CRH-BP immunoreactivity is localized in perikarya in the recessus opticus, a hypothalamic region distinct from the NPO, and colocalizes in CRHimmunopositive nerve fibers projecting from the NPO to pituitary corticotropes (Huising et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Experimental hyperthyroidism and central mediators of stress axis and thyroid axis activity in common carp (Cyprinus carpio L.)

Geven¹,

Verkaar²,

Flik³

et al. 2006

Journal of Molecular Endocrinology

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The effect of experimental hyperthyroidism, realized by T 4 injection, on central mediators of the hypothalamo-pituitaryinterrenal axis (HPI-axis) in common carp (Cyprinus carpio L.) was studied. Our results show that hyperthyroidism evokes a marked 3 . 2-fold reduction in basal plasma cortisol levels. Corticotropin-releasing hormone-binding protein (CRH-BP) mRNA levels in the hypothalamus, measured by real-time quantitative PCR, were significantly elevated by 40%, but CRH, urotensin-I, prepro-TRH, prohormone convertase-1 (PC1), and POMC mRNA levels were unchanged. In the pituitary pars distalis, PC1, CRH receptor-1, and POMC mRNA levels were unaffected, as was ACTH content. Plasma a-MSH concentrations were significantly elevated by 30% in hyperthyroid fish, and this was reflected in PC1 and POMC mRNA levels in pituitary pars intermedia that were increased 1 . 5-and 2 . 4-fold respectively. The a-MSH content of the pars intermedia was unchanged. Hyperthyroidism has profound effects on the basal levels of a central mediator, i.e., CRH-BP, of HPI-axis function in unstressed carp in vivo, and we conclude that HPI-and hypothalamo-pituitary-thyroidaxis functions are strongly interrelated. We suggest that the changes in plasma cortisol, thyroid hormone, and a-MSH levels reflect their concerted actions on energy metabolism.

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CRH-BP: the regulation and function of a phylogenetically conserved binding protein

Cited by 115 publications

References 110 publications

Central and peripheral integration of interrenal and thyroid axes signals in common carp (Cyprinus carpio L.)

Central and peripheral integration of interrenal and thyroid axes signals in common carp (Cyprinus carpio L.)

Sequences, expression patterns and regulation of the corticotropin-releasing factor system in a teleost

Experimental hyperthyroidism and central mediators of stress axis and thyroid axis activity in common carp (Cyprinus carpio L.)

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