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BEACON

Examination of hypothalamic mRNA has led to the discovery of a small protein termed Beacon (Collier et al, 2000). ICV administration of Beacon increased NPY expression and stimulated food intake in a dose-dependent manner. Simultaneous infusion of Beacon with NPY significantly potentiated orexigenic responses and results in rapid body weigh gain. Beacon has been found through immunohistochemical methods to be present in a wide variety of brain areas suggesting that in addition to a role in feeding, it may possess a multitude of biological activities associated with the hypothalamic-pituitary axis (Brailou et al, 2000).

Collier G. R. , et al. A Novel gene involved in the regulation of energy balance. Diabetes 49:1766-1771, 2000.

Brailoiu GC, Dun SL, Yang J, Chang JK, Castellino S, Dun NJ. Beacon-like immunoreactivity in the hypothalamus of Sprague-Dawley rats. Neurosci Lett 2002 Jan 14;317(3):166-8

Walder K, Ziv E, Kalman R, Whitecross K, Shafrir E, Zimmet P, Collier GR. Elevated hypothalamic beacon gene expression in Psammomys obesus prone to develop obesity and type 2 diabetes. Int J Obes Relat Metab Disord 2002 May;26(5):605-9


Distribution of beacon immunoreactivity in the rat brain

Beacon is a novel peptide isolated from the hypothalamus of Israeli sand rat. In the present study, we determined the distribution of beacon in the rat brain using immunohistochemical approachwith a polyclonal antiserum directed against the synthetic C-terminal peptide fragment (47–73). The hypothalamus represented the major site of beacon-immunoreactive (IR) cell bodies that were concentrated in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON). Additional immunostained cells were found in the septum, bed nucleus of the stria terminalis, subfornical organ and subcommissural organ. Beacon- IR fibers were seen with high density in the internal layer of the median eminence and low to moderate density in the external layer. Significant beacon-IR fibers were also seen in the nucleus of the solitary tract and lateral reticular formation. The beacon neurons found in the PVN were further characterized by double label immunohistochemistry. Several beacon- IR neurons that resided in the medial PVN were shown to coexpress corticotrophinreleasing hormone (CRH) and most labeled beacon fibers in the external layer of median eminence coexist with CRH. The topographical distribution of beacon-IR in the brain suggests multiple biological activities for beacon in addition to its proposed roles in modulating feeding behaviors and pituitary hormone release.

Wang F., et al. Peptides, 27 ( 2006 ) 165–171


Differential expression and function of beacon in the rat adrenal cortex and medulla

Beacon gene is overexpressed in obese rats, and beacon was found to stimulate food intake. Evidence has been recently provided that beacon is also expressed in the endocrine glands of normal rats, including adrenal cortex, of which it appears to regulate secretory activity. To further characterize the role of beacon in the rat adrenals, we investigated the level of beacon expression in the adrenal zona glomerulosa (ZG), zona fasciculata-reticularis (ZF/R) and medulla (AM), and the in vitro secretory responses to beacon[47-73] (hereinafter, beacon) of adrenocortical and adrenomedullary tissues. Real-time polymerase chain reaction revealed similar high levels of beacon mRNA in the ZG and ZF/R, and significantly lower (-80%) levels in AM. Immunocytochemistry showed that the distribution of beacon protein followed that of beacon mRNA. Quantitative high pressure liquid chromatography demonstrated that beacon (5x10(-7) M) reduced by about 56% the in vitro total steroid-hormone production from ZG and ZF/R tissues, without affecting catecholamine secretion from AM specimens. The beacon-induced lowering in the secretory activity of adrenal cortex depended on similar reductions (from 50-64%) in the production of the main adrenocortical hormones (pregnenolone, progesterone, 11-deoxycorticosterone, corticosterone, 18-hydroxy-corticosterone and aldosterone), thereby suggesting an inhibitory action of beacon in the early step of steroidogenesis (i.e. the conversion of cholesterol to pregnenolone). The hypothesis is advanced that beacon is to be considered an autocrine-paracrine negative regulator of mineralo- and glucocorticoid synthesis in the rat adrenal gland.

Rucinski M, et al. Int J Mol Med. 2005 Jul;16(1):35-40

 

Expression of the beacon gene in the rat pancreatic islets: opposite effects of beacon (47-73) protein (ubiquitin-like protein 5) on insulin secretion in vivo and insulin release by isolated islets

OBJECTIVE: Beacon gene expression is elevated in the hypothalamus of the Israeli sand rat (Psammomys obesus), an animal that is used as a polygenic animal model of obesity and NIDDM. We performed studies aimed at investigating the expression of beacon mRNA and protein in pancreatic islets of the rat and the possible beacon protein effects on insulin secretion.
METHODS: Rat pancreatic islets were isolated by the collagenase digestion technique. Beacon mRNA expression was demonstrated in isolated islets using RT-PCR and beacon-like immunoreactivity using immunocytochemistry (ICC) on a sections of Bouin-fixed pancreas. Isolated islets were incubated with 1-100 nmol/L beacon (47-73) protein in normoglycemic medium. Adult female rats were subcutaneously injected with beacon (47-73) at doses 0.35 or 0.7 nmol/100 g body weight and killed after 30 and 60 minutes.
RESULTS: RT-PCR results indicate the presence of beacon mRNA in isolated rat pancreatic islets. Beacon-like immunoreactivity is present in all cell types of the Langerhans islet. Beacon inhibits insulin secretion from isolated islets. In contrast, a bolus administration of beacon at a lower dose notably stimulates blood insulin concentration at 30 and 60 minutes of the experiment while the higher dose does not change insulinemia. None of the treatment had an effect on blood glucose concentration.
CONCLUSION: This study demonstrated the presence of beacon mRNA in isolated rat islets as well as a direct inhibitory effect of beacon protein on insulin secretion by isolated rat pancreatic islets. The data obtained suggest that beacon may be involved in physiologic regulation of insulin secretion.

Nowak KW, et al. Pancreas. 2004 Aug;29(2):99-103

 

Beacon[47-73] inhibits glucocorticoid secretion and growth of cultured rat and human adrenocortical cells

Evidence has been recently provided that beacon, an ubiquitin-like protein overexpressed in the hypothalamus of Israeli sand rat, is also expressed in several endocrine glands of the Wistar rat, including adrenal cortex. Moreover, it has been shown that the in vivo administration of beacon[47-73] (hereinafter, beacon) evokes within 60 min a marked decrease in the plasma concentrations of ACTH and corticosterone. Hence, we have investigated the effect of beacon (4x10(-9) or 4x10(-7) M) on the secretion and growth of cultured rat and human zona fasciculata/reticularis (ZF/R) cells. Reverse transcription-polymerase chain reaction detected beacon mRNA in all human adrenal cortexes examined. A 3-h exposure to beacon was ineffective, but prolonged (24 and 96 h) exposures significantly lowered basal corticosterone and cortisol secretion from cultured rat and human ZF/R cells, respectively. Moreover, beacon (4x10(-7) M) counteracted the secretagogue action of 10(-8) M ACTH on cultured cells. The 96-h exposure to beacon concentration-dependently decreased basal proliferation rate of cultured cells, without inducing significant changes in the number of apoptotic and necrotic cells. Beacon (4x10(-7) M) significantly inhibited the proliferogenic effect of 10(-8) M adrenomedullin. In light of the involvement of ubiquitin-like proteins in the control of cell cycle and protein sorting and degradation, the hypothesis is advanced that the inhibitory effect of beacon on the secretion and growth of cultured rat ZF/R cells may be connected to its stimulating effect on proteolysis of steroidogenic enzymes and proteins involved in cell replication.

Ziolkowska A, et al. Int J Mol Med. 2004 Sep;14(3):457-61

 

Beacon-like immunoreactivity in the hypothalamus of Sprague-Dawley rats

Distribution of the novel peptide beacon in the hypothalamus of Sprague-Dawley rats was examined by immunohistochemical methods. Beacon-immunoreactive (irBC) neurons were found in the paraventricular, supraoptic, and accessory neurosecretory nuclei, and intensely labeled fibers in the median eminence and infundibulo-pituitary stalk. Scattered cells and/or fibers were noted in the suprachiasmatic nucleus, arcuate nucleus, retrochiasmatic area, lateral and medial preoptic area, as well as anterior and lateral hypothalamic area. The wide distribution of irBC in the hypothalamus of Sprague-Dawley rats suggests that the peptide may influence, in addition to a proposed role in feeding, a multitude of biological activities associated with the hypothalamic-pituitary axis.

Brailoiu GC, Dun SL, Yang J, Chang JK, Castellino S, Dun NJ. Neurosci Lett 2002 Jan 14;317(3):166-8

Stained the hypothalamus of SD rats with anti-Beacon (47-73) antiserum (H-072-50)

 

beacon

Coronal sections illustrating the distribution of beacon-containing cell bodies and nerve fibers in the dorsal lateral septal nucleus (LSD) (A) and the medial posterior region of the bed nucleus of the stria terminalis (BNSTMP) (B). Scale bar = 200 mm. Wang F., et al. Peptides, 27 (2006) (165–171) [Primary antibody: Rabbit Anti Beacon (47-73) Antiserum, H-072-50].

beacon

Coronal sections showing neurons containing beacon-IR in the hypothalamus. The main population of beacon-IR cells were noted in the PVN (A) and SON (B). In the PVN, beacon-positive cell bodies and nerve fibers were found both in the magnocellular and parvocellular part of the nucleus (A). Quite a number of beacon-IR neurons and nerve fibers were detected in the SCN (C) and SOR (D).
Abbreviation: dp, dorsal parvocellular; mp, medial parvocellular; F, fornix; OX, optic chiasm; 3V, third ventricle. Scale bar = 200 mm.

Wang F., et al. Peptides, 27 ( 2006 ) 165–171

beacon

Coronal sections illustrating beacon-stained nerve fibers in the nucleus of the solitary tract (NTS) (A and B) and the lateral reticular nucleus (LRt) (C). Abbreviation: AP, area postrema; cc, central canal; ncom, commissural nucleus of NTS; mNTS, medial subnucleus of NTS. Scale bar = 200 mm.

Wang F., et al. Peptides, 27 ( 2006 ) 165–171

beacon

beacon

beacon

Coronal sections illustrating the localization of beacon-IR in circumventricular organs including SFO (A and C), ME (B and D) and SCO (C and F). A group of intensely stained beacon-positive cell bodies was detected in the lateral margin of the SFO (A and C). In the ME, most Beacon-IR fibers were seen in the internal layer (B and D). In the SCO, both the ependymal (E) and hypendymal (H) cells are beacon-IR. The arrow shows the blood vessel between the hypendymal cells and basal processes of the ependymal cells. Abbreviation: LV, lateral ventricle; 3V, third ventricle; PC, posterior commissure. Scale bar = 100 mm.

Wang F., et al. Peptides, 27 ( 2006 ) 165–171

 

Confocal images of rat paraventricular hypothalamic nucleus double-labeled with beacon-antiserum and CRHantiserum. Section labeled with beacon- (A) and CRH-antiserum(B); and an overlay of the images (A) and (B) (C); (D) is a high magnification of (C). Several beacon-containing neurons were CRH-IR positive (arrows) and some beacon-containing fibers were in close contact with CRH-IR neurons (arrowheads). Scale bar = 40 mm.

Confocal images of rat ME double-labeled with beacon-antiserum and CRH-antiserum. Most beacon-containing fibers in the external layer are CRH-immunoreactive (arrows), but several beacon-IR fibers (arrowhead) are not CRH-positive. Scale bar = 40 mm.

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