Fibroblasts expressing mouse c locus tyrosinase produce an authentic enzyme and synthesize phaeomelanin

1993 ◽  
Vol 104 (2) ◽  
pp. 467-475 ◽  
Author(s):  
A.J. Winder ◽  
A. Wittbjer ◽  
E. Rosengren ◽  
H. Rorsman
Keyword(s):  
Cell Types ◽  
Tyrosinase Activity ◽  
Melanin Synthesis ◽  
Post Translational Modification ◽  
Heterologous Promoter ◽  
Dopachrome Tautomerase ◽  
Membrane Bound ◽  
Related Proteins ◽  
Melanocytic Differentiation ◽  
Melanoma Cell Lines

Recent advances in the study of the molecular biology of mouse pigmentation have led to the discovery of a family of proteins involved in the control of melanin synthesis. It has been confirmed that the product of the mouse c (albino) locus is the key melanogenic enzyme tyrosinase, but study of its function and regulation have been hampered by the presence of closely related proteins within melanin-synthesising cells. To overcome these problems, we have established lines of mouse fibroblasts expressing the c locus mouse tyrosinase. Here we describe characterisation of the tyrosinase synthesised by these cells and demonstrate considerable similarity between the expressed tyrosinase and the native enzyme. The expressed tyrosinase is proteolytically cleaved to produce membrane-bound and soluble forms of the expected molecular mass and is rich in N-linked carbohydrate, suggesting that melanocytic differentiation is not a prerequisite for post-translational modification of the protein. The expressed enzyme has tyrosinase activity, but not catalase or dopachrome tautomerase activity, confirming that it is an authentic tyrosinase. Transfected fibroblasts expressing tyrosinase are shown to share several physiological characteristics with melanoma cell lines, including increased pigmentation and tyrosinase activity in response to increased cell density. Since tyrosinase is expressed under a heterologous promoter, these shared characteristics probably reflect translational or post-translational controls that operate in both non-melanocytic and melanocytic cell types. We demonstrate that pigmented fibroblasts contain the melanin synthesis intermediates 5-S-cysteinyldopa and 5-S-glutathionyl-dopa, and produce a phaeomelanin-like pigment, but do not contain detectable eumelanin. Expression of tyrosine is therefore sufficient for the synthesis of a form of melanin pigment in fibroblasts.

Dissection of functional domains in Bcl-2α by site-directed mutagenesis

1994 ◽  
Vol 72 (11-12) ◽  
pp. 463-469 ◽  
Author(s):  
Christoph Borner ◽  
Reynald Olivier ◽  
Isabelle Martinou ◽  
Chantal Mattmann ◽  
Jurg Tschopp ◽  
...  
Keyword(s):  
Cell Survival ◽  
Protein Structures ◽  
Cell Types ◽  
Site Directed Mutagenesis ◽  
Functional Domains ◽  
Directed Mutagenesis ◽  
Membrane Attachment ◽  
Alternatively Spliced ◽  
Membrane Bound ◽  
Related Proteins

Bcl-2α is a mitochondrial or perinuclear-associated oncoprotein that prolongs the life span of a variety of cell types by interfering with programmed cell death. How Bcl-2 confers cell survival is unknown, although antioxidant and antiprotease functions have been proposed. In addition, protein structures of Bcl-2 that are crucial for its survival activity are still ill-defined. Bcl-2 can occur as Bcl-2α or Bcl-2β, two alternatively spliced forms which solely differ in their carboxyl termini. The finding that Bcl-2α is active and membrane bound, but Bcl-2β is inactive and cytosolic, indicates that the carboxyl terminus contributes to the survival activity of Bcl-2. This region contains two subdomains, a domain X with unknown function and a hydrophobic stretch reported to mediate membrane assocation of Bcl-2α. Recently Bcl-2-related proteins have been identified. These include Bax that heterodimerizes with Bcl-2 and, when overxpressed, counteracts Bcl-2. Bax contains two highly conserved regions of sequence homology with Bcl-2, referred to as Bcl-2 homology 1 and 2 (BH1 and BH2) domains. Site-directed mutagenesis studies have revealed that both domains are not only novel dimerization motifs for the interaction of Bax with Bcl-2 but also crucial for the survival activity of Bcl-2. Interestingly, the C-terminal end of BH2 encompasses the Bcl-2α/β splice site, as well as part of domain X in Bcl-2α. To better define the role of domain X and the hydrophobic C-terminal stretch of Bcl-2α for its survival activity, we created various deletion and truncation mutations in these regions by site-directed mutagenesis. We show here that membrane attachment and therefore the hydrophobic stretch is not required for the survival activity of Bcl-2, but part of domain X appears to be indispensable.Key words: apoptosis, Bcl-2, mutagenesis, cell survival, functional domains.

scholarly journals Induction of pigmentation in mouse fibroblasts by expression of human tyrosinase cDNA.

1989 ◽  
Vol 169 (6) ◽  
pp. 2029-2042 ◽  
Author(s):  
B Bouchard ◽  
B B Fuller ◽  
S Vijayasaradhi ◽  
A N Houghton
Keyword(s):  
Cell Lines ◽  
Melanoma Cell ◽  
Tyrosinase Activity ◽  
Antigenic Determinants ◽  
Distinguishing Characteristic ◽  
Mouse Fibroblasts ◽  
Stable Production ◽  
Membrane Bound ◽  
Melanoma Cell Lines ◽  
Human Tyrosinase

A distinguishing characteristic of cells of the melanocyte lineage is the expression of the melanosomal enzyme tyrosinase that catalyzes the synthesis of the pigment melanin. A tyrosinase cDNA clone, designated BBTY-1, was isolated from a library constructed from the pigmented TA99+/CF21+ melanoma cell line SK-MEL-19. Expression of BBTY-1 in mouse L929 fibroblasts led to synthesis and expression of active tyrosinase, and, unexpectedly, to stable production of melanin. Melanin was synthesized and stored within membrane-bound vesicles in the cytoplasm of transfected fibroblasts. BBTY-1 detected a 2.4-kb mRNA transcript in nine of nine pigmented, tyrosinase-positive melanoma cell lines. Tyrosinase transcripts of the same size and abundance were detected in a subset (three of eight) of nonpigmented, tyrosinase-negative melanoma cell lines, suggesting that post-transcriptional events are important in regulating tyrosinase activity. Two melanocyte antigens, recognized by mAbs TA99 and CF21, that are specifically located within melanosomes and are coexpressed with tyrosinase activity, did not react with transfected mouse fibroblasts expressing human tyrosinase, supporting the conclusion that these antigenic determinants are distinct from the tyrosinase molecule coded for by BBTY-1.

scholarly journals Interferon-gamma Induces Melanogenesis Via Post-Translational Modification of Tyrosinase

2021 ◽  
Author(s):  
Xuan Mo ◽  
Hasan Raza Kazmi ◽  
Sarah Preston-Alp ◽  
Bo Zhou ◽  
M. Raza Zaidi
Keyword(s):  
Interferon Gamma ◽  
De Novo ◽  
Type I ◽  
Post Translational Modification ◽  
Dopachrome Tautomerase ◽  
Melanocyte Stimulating Hormone ◽  
Ifn Alpha ◽  
Pathway Inhibition ◽  
Related Proteins ◽  
Rate Limiting

Melanogenesis (melanin pigment production) in melanocytes is canonically stimulated by the alpha-melanocyte stimulating hormone (αMSH), which activates the cyclic-AMP-mediated expression of the melanocyte inducing transcription factor (MITF) and its downstream melanogenic genes, including the principal rate-limiting melanogenic enzyme tyrosinase (Tyr). Here we report that interferon-gamma (IFNG; type II interferon), but not IFN-alpha (a type I interferon), induces a noncanonical melanogenic pathway. Inhibition of IFNG pathway by the JAK inhibitor ruxolitinib or knocking out Stat1 abrogated the IFNG-induced melanogenesis. Interestingly, IFNG-induced melanogenesis was independent of MITF. IFNG markedly increased the Tyr protein expression but did not affect the mRNA expression, suggesting a post-translational regulatory mechanism. In contrast, IFNG had no effect on the expression of other melanogenesis-related proteins, e.g. tyrosinase-related protein 1 (Tyrp1) and dopachrome tautomerase (Dct). Glycosidase digestion assays revealed that IFNG treatment increased the mature glycosylated form of Tyr, but not its de novo synthesis. Moreover, cycloheximide chase assay showed that degradation of Tyr was decreased in IFNG-treated cells. These results suggest that the IFNG-STAT1 pathway regulates melanogenesis via modulation of the post-translational processing and protein stability of Tyr.

scholarly journals Inhibitory Effects of Cycloheterophyllin on Melanin Synthesis

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2526
Author(s):  
Joong-Hyun Shim
Keyword(s):  
Functional Materials ◽  
Tyrosinase Activity ◽  
Melanin Synthesis ◽  
Activity Assay ◽  
Inhibitory Effects ◽  
Melanin Production ◽  
Messenger Ribonucleic Acid ◽  
B16f10 Cells ◽  
Cell Line Cell ◽  
Tyrosinase Related Protein

This study was performed to clarify the inhibitory effects of cycloheterophyllin on melanin synthesis. In order to elucidate the inhibitory effects of cycloheterophyllin on the B16F10 cell line, cell viability, messenger ribonucleic acid (mRNA) expressions, tyrosinase activity assay, and melanin production assay were measured. The effects of cycloheterophyllin on tyrosinase-related protein 1 (TYRP1)/TYRP2/tyrosinase (TYR)/microphthalmia-associated transcription factor (MITF) mRNA expressions and melanin content were determined. Quantitative real-time RT-PCR showed that cycloheterophyllin decreased the mRNA expression level of TYRP1/TYRP2/TYR/MITF genes and melanin production contents than α-MSH-treated B16F10 cells. The tyrosinase activity assay revealed that cycloheterophyllin decreased the melanin production in the B16F10 cells. These data show that cycloheterophyllin increases the whitening effects in the B16F10 cells; thus, cycloheterophyllin is a potent ingredient for skin whitening. Thus, further research on the mechanism of action of cycloheterophyllin for the development of functional materials should be investigated.

scholarly journals Aptamers selected against the unglycosylated EGFRvIII ectodomain and delivered intracellularly reduce membrane-bound EGFRvIII and induce apoptosis

2009 ◽  
Vol 390 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Yingmiao Liu ◽  
Chien-Tsun Kuan ◽  
Jing Mi ◽  
Xiuwu Zhang ◽  
Bryan M. Clary ◽  
...  
Keyword(s):  
Growth Factor Receptor ◽  
Rna Aptamers ◽  
Normal Brain ◽  
Post Translational Modification ◽  
Expression And Purification ◽  
Post Translational Modifications ◽  
Protein Expression And Purification ◽  
Epidermal Growth ◽  
Membrane Bound

Abstract Epidermal growth factor receptor variant III (EGFRvIII) is a glycoprotein uniquely expressed in glioblastoma, but not in normal brain tissues. To develop targeted therapies for brain tumors, we selected RNA aptamers against the histidine-tagged EGFRvIII ectodomain, using an Escherichia coli system for protein expression and purification. Representative aptamer E21 has a dissociation constant (Kd) of 33×10-9 m, and exhibits high affinity and specificity for EGFRvIII in ELISA and surface plasmon resonance assays. However, selected aptamers cannot bind the same protein expressed from eukaryotic cells because glycosylation, a post-translational modification present only in eukaryotic systems, significantly alters the structure of the target protein. By transfecting EGFRvIII aptamers into cells, we find that membrane-bound, glycosylated EGFRvIII is reduced and the percentage of cells undergoing apoptosis is increased. We postulate that transfected aptamers can interact with newly synthesized EGFRvIII, disrupt proper glycosylation, and reduce the amount of mature EGFRvIII reaching the cell surface. Our work establishes the feasibility of disrupting protein post-translational modifications in situ with aptamers. This finding is useful for elucidating the function of proteins of interest with various modifications, as well as dissecting signal transduction pathways.

Cytoplasmic, nuclear, membrane-bound and secreted [35S]methionine-labelled polypeptide pattern in differentiating fibroblast stem cells in vitro

1989 ◽  
Vol 92 (2) ◽  
pp. 231-239
Author(s):  
P.I. Francz ◽  
K. Bayreuther ◽  
H.P. Rodemann
Keyword(s):  
Protein Fraction ◽  
Fibroblast Cell ◽  
Cell Types ◽  
Specific Marker ◽  
Human Skin Fibroblast ◽  
Nuclear Fraction ◽  
Cell Type ◽  
Marker Proteins ◽  
Cell Type Specific ◽  
Membrane Bound

Methods for the selective enrichment of various subpopulations of the human skin fibroblast cell line HH-8 have been developed. These methods permit the selection of homogeneous populations of the three mitotic fibroblast cell types MF I, II and III, and the four postmitotic cell types PMF IV, V, VI and VII. These seven cell types exhibit differentiation-dependent and cell-type-specific patterns of [35S]methionine-labelled polypeptides in total soluble cytoplasmic and nuclear proteins, also in membrane-bound proteins, and in secreted proteins. In the differentiation sequence MF II-MF III-PMF IV - PMF V - PMF VI 14 cell-type-specific marker proteins have been found in the cytoplasmic and nuclear fraction, also 24 cell-type-specific marker proteins have been found in the membrane-bound protein fraction, and 11 cell-type-specific marker proteins in the secreted protein fraction. Markers in spontaneously arising and experimentally selected or induced populations of a single fibroblast cell type were found to be identical.

scholarly journals Di-Tyrosine Crosslinking and NOX4 Expression as Oxidative Pathological Markers in the Lungs of Patients with Idiopathic Pulmonary Fibrosis

Antioxidants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1833
Author(s):  
Sanja Blaskovic ◽  
Yves Donati ◽  
Isabelle Ruchonnet-Metrailler ◽  
Tamara Seredenina ◽  
Karl-Heinz Krause ◽  
...  
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Human Fibroblasts ◽  
Cell Types ◽  
Post Translational Modification ◽  
Pulmonary Tissue ◽  
Nadph Oxidase 4

Idiopathic pulmonary fibrosis (IPF) is a noninflammatory progressive lung disease. Oxidative damage is a hallmark of IPF, but the sources and consequences of oxidant generation in the lungs are unclear. In this study, we addressed the link between the H2O2-generating enzyme NADPH oxidase 4 (NOX4) and di-tyrosine (DT), an oxidative post-translational modification in IPF lungs. We performed immunohistochemical staining for DT and NOX4 in pulmonary tissue from patients with IPF and controls using validated antibodies. In the healthy lung, DT showed little or no staining and NOX4 was mostly present in normal vascular endothelium. On the other hand, both markers were detected in several cell types in the IPF patients, including vascular smooth muscle cells and epithelium (bronchial cells and epithelial cells type II). The link between NOX4 and DT was addressed in human fibroblasts deficient for NOX4 activity (mutation in the CYBA gene). Induction of NOX4 by Transforming growth factor beta 1 (TGFβ1) in fibroblasts led to moderate DT staining after the addition of a heme-containing peroxidase in control cells but not in the fibroblasts deficient for NOX4 activity. Our data indicate that DT is a histological marker of IPF and that NOX4 can generate a sufficient amount of H2O2 for DT formation in vitro.

scholarly journals Neutrophil azurophilic granule glycoproteins are distinctively decorated by atypical pauci- and phosphomannose glycans

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Karli R. Reiding ◽  
Yu-Hsien Lin ◽  
Floris P. J. van Alphen ◽  
Alexander B. Meijer ◽  
Albert J. R. Heck
Keyword(s):  
Immune System ◽  
Autoimmune Disease ◽  
Secreted Proteins ◽  
Receptor Interaction ◽  
Post Translational Modification ◽  
Site Specific ◽  
Healthy Donors ◽  
Asymmetric Hybrid ◽  
Membrane Bound ◽  
High Mannose

AbstractWhile neutrophils are critical first-responders of the immune system, they also cause tissue damage and act in a variety of autoimmune diseases. Many neutrophil proteins are N-glycosylated, a post-translational modification that may affect, among others, enzymatic activity, receptor interaction, and protein backbone accessibility. So far, a handful neutrophil proteins were reported to be decorated with atypical small glycans (paucimannose and smaller) and phosphomannosylated glycans. To elucidate the occurrence of these atypical glycoforms across the neutrophil proteome, we performed LC-MS/MS-based (glyco)proteomics of pooled neutrophils from healthy donors, obtaining site-specific N-glycan characterisation of >200 glycoproteins. We found that glycoproteins that are typically membrane-bound to be mostly decorated with high-mannose/complex N-glycans, while secreted proteins mainly harboured complex N-glycans. In contrast, proteins inferred to originate from azurophilic granules carried distinct and abundant paucimannosylation, asymmetric/hybrid glycans, and glycan phosphomannosylation. As these same proteins are often autoantigenic, uncovering their atypical glycosylation characteristics is an important step towards understanding autoimmune disease and improving treatment.

scholarly journals Synthesis of p36 and p35 is increased when U-937 cells differentiate in culture but expression is not inducible by glucocorticoids.

1989 ◽  
Vol 9 (1) ◽  
pp. 232-240 ◽  
Author(s):  
C M Isacke ◽  
R A Lindberg ◽  
T Hunter
Keyword(s):  
Tyrosine Kinases ◽  
Myeloid Cell ◽  
Cell Types ◽  
Culture Conditions ◽  
Actin Binding ◽  
Myeloid Cell Line ◽  
Related Proteins ◽  
Cortical Cytoskeleton ◽  
Inflammatory Action ◽  
Human Specific

p36 and p35 are distinct but related proteins that share many structural and biochemical features which were first identified as major substrates for protein-tyrosine kinases. Subsequently, both proteins have been shown to be Ca2+-, phospholipid-, and F-actin-binding proteins that underlie the plasma membrane and are associated with the cortical cytoskeleton. Recent reports have claimed that these proteins function as lipocortins, i.e., phospholipase A2 inhibitors that mediate the anti-inflammatory action of glucocorticoids. To investigate this possibility and to learn more about the functions of p36 and p35, we used human-specific anti-p36 and anti-p35 monoclonal antibodies to determine whether the expression or secretion of either protein was inducible by dexamethasone in the human U-937 myeloid cell line and in other human cell types. Additionally, we examined the levels of mRNA for both proteins. No effect of dexamethasone was observed on p36 or p35 expression at either the mRNA or protein level, nor were these proteins secreted under any of the culture conditions investigated. However, it was observed that in these cells the rate of synthesis and accumulation of both proteins was increased when the U-937 cells were induced to differentiate in culture to adherent macrophagelike cells. This offers a model system with which to study the control of p36 and p35 expression.

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