A new in vitro melanophore bioassay for MSH using tail-fins of xenopus tadpoles

Graan, P.N.E. de; Molenaar, R.; Veerdonk, F. C. G. van de

doi:10.1016/0303-7207(83)90088-6

Cited by 15 publications

(6 citation statements)

References 21 publications

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“…The molecular basis for this temporal change in vitro is unknown, although it may reflect a differential coupling of signal transduction pathways from melanopsin photoreception and/or receptors for melanin-aggregating/dispersing hormones. Nevertheless, our in vivo data, and that of others, are consistent with aggregation induced by light being present at any developmental time after stage 39/40 (De Graan et al, 1983;Imai and Takahashi, 1971;Verburg-van Kemenade et al, 1984).…”

Section: Discussionsupporting

confidence: 93%

“…While Xenopus melanopsin has not yet been purified, the spectral sensitivity data available for melanopsins across species indicate an absorption peak at approximately 480 nm (Bailes and Lucas, ; Walker et al., ). Spectral analysis of pigment aggregation in primary melanophore cultures or isolated Xenopus tail fins indicates that the maximum response is obtained from 460 to 500 nm (De Graan et al., ; Lythoe and Thompson, ; Moriya et al., ). The spectral responsiveness of pigment aggregation in whole animals, however, is not well understood (Silver, ).…”

Section: Resultsmentioning

confidence: 99%

“…To assess whether melanopsin acts locally on melanophores to regulate pigmentation, we turned to an isolated tail preparation, which isolates melanophores from neural and endocrine mediators of the secondary response (De Graan et al., ; Moriya et al., ). We measured the pigmentation indices resulting from AA92593 or α ‐MSH treatment of the entire embryo, isolated upper body or tail.…”

Section: Resultsmentioning

confidence: 99%

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Melanopsin photoreception in the eye regulates light‐induced skin colour changes through the production of α‐MSH in the pituitary gland

Bertolesi

Hehr

McFarlane

2015

Pigment Cell Melanoma Res

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How skin colour adjusts to circadian light/dark cycles is poorly understood. Melanopsin (Opn4) is expressed in melanophores, where in vitro studies suggest it regulates skin pigmentation through a 'primary colour response' in which light photosensitivity is translated directly into pigment movement. However, the entrainment of the circadian rhythm is regulated by a population of melanopsin-expressing retinal ganglion cells (mRGCs) in the eye. Therefore, in vivo, melanopsin may trigger a 'secondary colour response' initiated in the eye and controlled by the neuro-endocrine system. We analysed the expression of opn4m and opn4x and melanin aggregation induced by light (background adaptation) in Xenopus laevis embryos. While opn4m and opn4x are expressed at early developmental times, light-induced pigment aggregation requires the eye to become functional. Pharmacological inhibition of melanopsin suggests a model whereby mRGC activation lightens skin pigmentation via a secondary response involving negative regulation of alpha-melanocyte-stimulating hormone (α-MSH) secretion by the pituitary.

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Section: Discussionsupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Melanopsin photoreception in the eye regulates light‐induced skin colour changes through the production of α‐MSH in the pituitary gland

Bertolesi

Hehr

McFarlane

2015

Pigment Cell Melanoma Res

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“…The homogenate was centrifuged at 1000 × g for 10 min in a Sorvall SS34 rotor and the resultant supernate (S1) centrifuged for 10 min at 10000 x g in a Janetzki centrifuge to obtain the 10000 x g supernate (S 10). All homogenisation and centrifugation procedures were carried out at 0-4 ° C. The assay for melanotropic activity was carried out using the in vitro assay on Xenopus laevis tail-fin pieces as described by De Graan et al (1983), applying the melanophore index method for quantification of the response. The assay was carried out by an investigator who did not know the nature of the samples tested.…”

Section: Xenopus Laevis Test For Msh-like Activitymentioning

confidence: 99%

Evidence that the neurotrophic actions of α-MSH may derive from its ability to mimick the actions of a peptide formed in degenerating nerve stumps

Edwards¹,

Zee²,

Verhaagen³

et al. 1984

Journal of the Neurological Sciences

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SUMMARYThe ability of ~-MSH to facilitate the recovery of sensorimotor nerve function following crush lesion is restricted to a critical period following such a lesion. This period coincided with the initiation of sprouting and the disappearance of the 150 kD neurofilament protein from the degenerating distal stump of the nerve.Degenerating nerve contains a factor that is active in a bioassay system for MSH. This factor could not be detected in control nerves.The hypothesis is forwarded that a neurotrophic factor known to be present in degenerating nerve stumps is an ~-MSH-like peptide formed by the breakdown of the 150 kD neurofilament protein.

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“…Missense SNPs deposited at the NIH within the His-Phe-Arg-Trp sequence are indicated for each POMC-derived agonist. An asterisk (*) indicates a polymorphism or substitution in α-MSH that has previously been characterized (His → Gln, Phe → Leu, Arg → Cys, and Trp → Leu − ).…”

mentioning

confidence: 99%

Single Nucleotide Polymorphisms in the Melanocortin His-Phe-Arg-Trp Sequences Decrease Tetrapeptide Potency and Efficacy

Winget

Ericson

Freeman

et al. 2019

ACS Med. Chem. Lett.

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The melanocortin receptors are stimulated by agonists (α-MSH, β-MSH, γ-MSH, and ACTH) processed from the proopiomelanocortin (POMC) gene transcript and possess a common His-Phe-Arg-Trp tetrapeptide sequence critical for receptor activation. Deficiency in POMC signaling in humans is associated with adrenal insufficiency, altered pigmentation, and rapid, early onset weight gain. Herein, 12 single nucleotide polymorphisms (SNPs) deposited into the Variation Viewer database within the His-Phe-Arg-Trp sequences of ACTH/α-MSH, β-MSH, and γ-MSH were substituted into tetrapeptide scaffolds to examine the in vitro signaling effects of these polymorphisms at the cloned melanocortin receptors. Every polymorphism decreased agonist potency and/or efficacy at the melanocortin receptors assayed, indicating that polymorphisms within the signaling sequence of POMC-derived agonists negatively impacts receptor activation. Future work to incorporate these substitutions into the full-length POMC agonists would confirm these findings, identifying new patient populations that might benefit from therapeutic regiments to treat POMC-deficient signaling.

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A new in vitro melanophore bioassay for MSH using tail-fins of xenopus tadpoles

Cited by 15 publications

References 21 publications

Melanopsin photoreception in the eye regulates light‐induced skin colour changes through the production of α‐MSH in the pituitary gland

Melanopsin photoreception in the eye regulates light‐induced skin colour changes through the production of α‐MSH in the pituitary gland

Evidence that the neurotrophic actions of α-MSH may derive from its ability to mimick the actions of a peptide formed in degenerating nerve stumps

Single Nucleotide Polymorphisms in the Melanocortin His-Phe-Arg-Trp Sequences Decrease Tetrapeptide Potency and Efficacy

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