Conserved and divergent genes in apex and axis development of cnidarians

Despite their radial organization and their sister group position in the life tree, cnidarian species express during morphogenesis a large number of genes that are related to bilaterian developmental genes. Among those, homologs to forkhead, emx, aristaless, goosecoid, brachyury, wnt and nanos genes are regulated during apical patterning in cnidarians, suggesting that key components of early organizer activity were conserved across evolution and recruited for either anterior, axial, or dorso-ventral patterning in bilaterians. In contrast, the expression patterns of the cnidarian Hox-related genes suggest that the apical-basal axis of the cnidarian polyp and the anterior-posterior axis of bilaterians do not differentiate following homologous processes.     

Relationships among msx gene structure and function in zebrafish and other vertebrates

The zebrafish genome contains at least five msx homeobox genes, msxA, msxB, msxC, msxD, and the newly isolated msxE. Although these genes share structural features common to all Msx genes, phylogenetic analyses of protein sequences indicate that the msx genes from zebrafish are not orthologous to the Msx1 and Msx2 genes of mammals, birds, and amphibians. The zebrafish msxB and msxC are more closely related to each other and to the mouse Msx3. Similarly, although the combinatorial expression of the zebrafish msx genes in the embryonic dorsal neuroectoderm, visceral arches, fins, and sensory organs suggests functional similarities with the Msx genes of other vertebrates, differences in the expression patterns preclude precise assignment of orthological relationships. Distinct duplication events may have given rise to the msx genes of modern fish and other vertebrate lineages whereas many aspects of msx gene functions during embryonic development have been preserved.      

Correction of defective early tyrosinase processing by bafilomycin A1 and monensin in pink-eyed dilution melanocytes

Mutations in the human P gene result in oculocutaneous albinism type 2, the most common form of albinism. Mouse melan-p1 melanocytes, cultured from mice null at the homologous pink-eyed dilution (p) locus, exhibit defective melanin production. A variety of compounds including tyrosine, NH4Cl, bafilomycin A1, concanamycin, monensin, and nigericin are capable of restoring melanin synthesis in these cells. In the current study, we investigated the subcellular effects of bafilomycin A1 and monensin treatment of melan-p1 cells. Both agents play two roles in the processing of tyrosinase (Tyr) in melan-p1 cells. First, combined glycosidase digestion and immunoblotting analysis showed that these agents reduce levels of Tyr retained in the endoplasmic reticulum (ER) and facilitate the release of Tyr from the ER to the Golgi. Secondly, treatment with these compounds resulted in the stabilization of Tyr. Surprisingly, induction of melanin synthesis corresponds more closely with diminution of ER-retained Tyr, rather than the absolute amount of Tyr. Our results suggest that bafilomycin A1 and monensin induce melanin synthesis in melan-p1 cells mainly by facilitating Tyr processing from the ER to the Golgi by increasing the pH in either the ER or the ER-Golgi intermediate compartment.     

Down-regulation of melanin synthesis by a biphenyl derivative and its mechanism

Down-regulation of melanin synthesis is required for recovery of pigmentary disorders and it is known that direct inhibitors of tyrosinase, the key enzyme in melanin synthesis, such as hydroquinone with a phenol structure, suppress melanin synthesis. We screened several phenolic derivatives using B16 melanoma cells and found that a biphenyl derivative, 2,2'-dihydroxy-5,5'-dipropyl-biphenyl (DDB), down-regulated melanin synthesis effectively. Although DDB has a phenol structure, it did not inhibit tyrosinase in vitro, thus we examined its mechanism in detail. Western blotting revealed that the amount of tyrosinase was decreased by DDB, and pulse-chase labeling and immunoprecipitation analysis showed a decrease of mature tyrosinase and acceleration of tyrosinase degradation in its presence. These results suggest that DDB down-regulates melanin synthesis by inhibiting the maturation of tyrosinase, leading to acceleration of tyrosinase degradation.     

Enzymatic synthesis of arbutin undecylenic acid ester and its inhibitory effect on melanin synthesis

Transesterification of arbutin and undecylenic acid vinyl ester was catalyzed by alkaline protease, Bioprase, in dimethylformamide to get arbutin derivative having undecylenic acid at 6-position of glucose moiety, 6-O-undecylenoyl p-hydroxyphenyl beta-D-glucopyranoside. The reaction rate increased with increase of arbutin concentration, and when its concentration was 0.9 M, the conversion rate was more than 90% under addition of 2 M undecylenic acid vinyl ester. The obtained arbutin ester significantly suppressed melanin production in murine B16 melanoma cells.     

The anti-inflammatory function of adenine occurs through AMPK activation and its downstream transcriptional regulation in THP-1 cells

ABSTRACT

Pathogenic bacteria induced sepsis is a risk factor for hospital mortality. Monocyte-derived inflammatory cytokines participate in the sepsis progression. The anti-inflammatory effect of adenine has been previously reported by our laboratory and others. However, the mechanism of action has different opinions and remains unclear in monocyte. Here, adenine was found to significantly inhibit the secretion of lipopolysaccharide-induced inflammatory cytokines such as TNF-α, IL-1β and IL-6 in THP-1 cells. The bioinformatic analysis results showed that the anti-inflammatory function is possibly due to the inhibition of NF-κB signaling. And this result is confirmed by using immunocytochemistry. Moreover, this effect can be suppressed by the AMPK inhibitor. Results also showed that adenine can activate AMPK and its multiple downstream targets. Data from mass spectrometry showed that adenine promotes significant elevation of intracellular AMP. Our data indicate that the anti-inflammatory mechanism of adenine may involve adenine phosphoribosyltransferase-catalyzed intracellular AMP elevation, which stimulates AMPK activation.     

Changes in the proliferation and differentiation of neonatal mouse pink-eyed dilution melanocytes in the presence of excess tyrosine

Changes in the proliferation and differentiation of epidermal melanocytes derived from newborn mice wild-type at the pink-eyed dilution (p) locus (P/P) and from congenic mice mutant at that locus (p/p) were investigated in serum-free primary culture, with or without the addition of L-Tyr. Incubation with added L-Tyr inhibited the proliferation of P/P melanocytes in a concentration-dependent manner and inhibition was gradually augmented as the donor mice aged. In contrast, L-Tyr stimulated the proliferation of p/p melanoblasts-melanocytes derived from 0.5-day-old mice, but inhibited their proliferation when derived from 3.5- or 7.5-day-old mice. L-Tyr stimulated the differentiation of P/P melanocytes. However, almost all cells were undifferentiated melanoblasts in control cultures derived from 0.5-, 3.5- and 7.5-day-old p/p mice, but L-Tyr induced their differentiation as the age of the donor mice advanced. The content of the eumelanin marker, pyrrole-2,3,5-tricarboxylic acid as well as the pheomelanin marker, 4-amino-3-hydroxyphenylalanine in p/p melanocytes was greatly reduced compared with P/P melanocytes. However, the contents of eumelanin and its precursor, 5,6-dihydroxyindole-2-carboxylic acid, as well as the contents of pheomelanin and its precursor, 5-S-cysteinyldopa in culture media from p/p melanocytes were similar to those of P/P melanocytes at all ages tested. L-Tyr increased the content of eumelanin and pheomelanin two- to threefold in cultured cells and media derived from 0.5-, 3.5- and 7.5-day-old mice. These results suggest that the proliferation of p/p melanoblasts-melanocytes is stimulated by L-Tyr, and that the differentiation of melanocytes is induced by L-Tyr as the age of the donor mice advanced, although eumelanin and pheomelanin fail to accumulate in p/p melanocytes and are released from them at all ages of skin development.     

Conserved physical linkage of GnRH-R and RBM8 in the medaka and human genomes

Candidate genes for human type II gonadotropin-releasing hormone receptor (GnRH-RII) reside on two separate loci, 1q12-q21 and 14q21-23, yet neither locus generates functional GnRH-RII. Instead, their opposite DNA strands encode functional RNA-binding motif protein 8 (RBM8s), which is also encoded by another locus, 5q13-q14. To elucidate the mechanism through which such multiple human GnRH-RII/RBM8 loci arose, here we have defined an RBM8 locus in a comparative model species, the medaka Oryzias latipes. The medaka RBM8, which exists as a single copy gene, is linked to, but does not overlap with, GnRH-R2 on linkage group (LG) 16, demonstrating the ancient origin of the physical linkage between GnRH-R and RBM8. The medaka LG 16 contains orthologous segments to the human chromosome 1 and therefore the 1q12-q21 locus would be an originating human GnRH-RII/RBM8 segment. Furthermore, like the human RBM8s on 1q12-q21 and 5q13-q14 but not that on 14q21-q23, the medaka RBM8 is a multiexon gene, indicating that the 14q21-q23 and 5q13-q14 loci were generated by retrotransposition and segmental genomic duplication, respectively, of the originating 1q12-q21 locus.