Rat corticotropin-releasing hormone gene: sequence and tissue-specific expression

The rat corticotropin releasing hormone (CRH) gene has been isolated and characterized by DNA sequence analysis. The gene exhibits a structural organization similar to that of the human CRH gene. The nucleotide sequence encoding the entire rat CRH precursor is located on the second exon, while exon I encodes the 5'-untranslated region of the mRNA. Analysis of the nucleotide sequence homology between the human and rat CRH genes reveals several highly conserved regions including the CRH peptide-encoding sequence and the 5'-flanking sequence. RNA blot analysis demonstrates that CRH mRNA can be observed in numerous regions of the rat brain as well as the spinal cord, adrenal gland, pituitary, and testis.     

Synthesis and biological actions of melanin concentrating hormone

A melanin (melanosome) concentrating hormone, MCH, was synthesized and the methodology for its synthesis is detailed. This heptadecapeptide, H-Asp-Thr-Met-Arg-Cys-Met-Val-Gly-Arg-Val-Tyr-Arg-Pro-Cys-Trp-Glu-Val-OH , stimulated melanosome concentration (centripetal aggregation) within melanophores of all species of teleost fishes studied. Melanosome aggregation in response to MCH was not blocked by Dibenamine as was the response to norepinephrine (NE), demonstrating that melanosome aggregating responses to MCH and NE are mediated through separate receptors. Melanosome aggregation in response to MCH was reversed by an equimolar concentration of alpha-melanocyte stimulating hormone (alpha-MSH). In contrast, MCH stimulated melanosome dispersion (centrifugal movement) within melanophores of a frog (Rana pipiens) and a lizard (Anolis carolinensis). Therefore, MCH exhibits both melanosome concentrating and dispersing actions depending upon the species studied.     

Increased hypothalamic melanin concentrating hormone gene expression during energy restriction involves a melanocortin-independent, estrogen-sensitive mechanism

Increased expression of melanin concentrating hormone (MCH), an orexigenic neuropeptide produced by neurons in the lateral hypothalamic area (LHA), is implicated in the effect of energy restriction to increase food intake. Since melanocortins inhibit Mch gene expression, this effect of energy restriction to increase Mch signaling may involve reduced hypothalamic melanocortin signaling. Consistent with this hypothesis, we detected increased hypothalamic Mch mRNA levels in agouti (Ay) mice (by 102%; P < 0.05), a model of genetic obesity resulting from impaired melanocortin signaling, compared to wild-type controls. If reduced melanocortin signaling mediates the effect of energy restriction, hypothalamic Mch gene expression in Ay mice should not be increased further by energy restriction, since melanocortin signaling is impaired in these animals regardless of nutritional state. We therefore investigated the effects of energy restriction on hypothalamic Mch gene expression in both Ay mice and in wild-type mice with diet-induced obesity (DIO). Responses in these mice were compared to those induced by administration of 17beta-estradiol (E2) at a dose previously shown to reduce food intake and Mch expression in rats. In both Ay and DIO mice, energy restriction increased hypothalamic Mch mRNA levels (P < 0.05 for each) via a mechanism that was fully blocked by E2. However, E2 did not lower levels of Mch mRNA below basal values in Ay mice, whereas it did so in DIO mice. Thus, the effect of energy restriction to increase hypothalamic Mch gene expression involves an E2-sensitive mechanism that is not altered by impaired melanocortin signaling. By comparison, impaired melanocortin signaling increases hypothalamic Mch gene expression via a mechanism that is insensitive to E2. These findings suggest that while both energy restriction and reduced melanocortin signaling stimulate hypothalamic Mch gene expression, they do so via distinct mechanisms.     

Biaryl diamides as potent melanin concentrating hormone receptor 1 antagonists

Herein, we report the discovery of the potent and selective biaryl diamide derived MCH-R1 receptor antagonist 1, which was identified upon modification of a previously disclosed biaryl urea series. This paper describes one of the strategies incorporated to remove the highly mutagenic biarylaniline present in an otherwise promising biaryl urea series.     

Nucleotide sequence of rat tyrosine aminotransferase gene]

The previously unknown sequences of the coding and 3'-flanking regions of the rat tyrosine aminotransferase gene were determined. The boundaries of exons and repetitive elements were established using computer analysis.     

Melanin concentrating hormone. III. Melanin concentrating hormone (MCH): the message sequence

Melanin concentrating hormone (MCH) is a heptadecapeptide synthesized by the hypothalamus and secreted by the neurohypophysis of the teleost pituitary gland. MCH stimulates melanosome aggregation within teleost melanocytes but also exhibits MSH-like (melanosome dispersing) activity on tetrapod (frog and lizard) melanocytes. We have synthesized a number of MCH analogues to determine the essential features of the primary structure necessary to stimulate either melanosome aggregation or dispersion in fish or tetrapod melanocytes, respectively. An analysis of the potencies and actions of these analogues on vertebrate melanocytes is provided and demonstrates that the two activities have different structural requirements.     

Discovery of tetralin ureas as potent melanin concentrating hormone 1 receptor antagonists

Melanin concentrating hormone (MCH) plays an important role in the regulation of food intake and energy balance in mammals. MCH-1 receptor (MCH1R) deficient mice are lean and resistant to diet-induced obesity. As such, MCH1R antagonists are believed to have potential as possible treatments for obesity. The discovery of a novel class of tetralin ureas as potent MCH1R antagonists is described herein.     

Synthesis and bioactivity studies of two isosteric acyclic analogues of melanin concentrating hormone.

Salmon melanin concentrating hormone (MCH) is a cyclic heptadecapeptide. MCH stimulates perinuclear aggregation of melanosomes within integumental melanocytes of teleost fishes resulting in skin blanching. MCH contains a disulfide bridge forming a 10-residue ring [sequence: see text]. It has been proposed that the ring is necessary for maintenance of potency. In order to test this proposal, we have synthesized two pseudo-isosteric analogues of MCH that cannot cyclize. They differed only in the polarity of the side chain group of positions 5 and 14. Serine was substituted for Cys5 and Cys14 in one peptide and L alpha-aminobutyrate (Abu) was the substitution at the two positions in the other peptide. Using a fish skin bioassay we determined that these analogues exhibit less than 1/10,000th the potency of the native hormone. These results suggest that the disulfide bridge is necessary to maintain the correct conformational and topographical features of the hormone for receptor binding and transmembrane signal transduction.     

Nucleotide sequence analysis and heterologous expression of the Erysipelothrix rhusiopathiae dnaJ gene

Abstract DNA sequence analysis of chromosomal DNA from the Gram-positive facultative intracellular pathogen, Erysipelothrix rhusiopathiae has identified a dnaJ heat shock gene homolog. A 1109-bp open reading frame encoding dnaJ is located immediately 3' to the E. rhusiopathiae dnaK gene. The deduced DnaJ amino acid sequence exhibits the modular structure of other members of the DnaJ protein class including a glycine-rich region and the repeating consensus sequence CXXCXGXGX. Heterologous expression of the dnaJ sequence in Escherichia coli resulted in accumulation of a unique 38.9-kDa protein with an isoelectric point of 8.0. Deletion analysis of the dnaJ gene was used to confirm that the overproduced protein was encoded by the dnaJ sequence.