scholarly journals Terminal differentiation and senescence in the human melanocyte: repression of tyrosine-phosphorylation of the extracellular signal-regulated kinase 2 selectively defines the two phenotypes.

1994 ◽  
Vol 5 (4) ◽  
pp. 497-509 ◽  
Author(s):  
E E Medrano ◽  
F Yang ◽  
R Boissy ◽  
J Farooqui ◽  
V Shah ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Phorbol Esters ◽  
Second Messengers ◽  
Terminal Differentiation ◽  
Fold Increase ◽  
Nuclear Accumulation ◽  
Growth Promoters ◽  
Critical Pathway ◽  
Differentiated Cells ◽  
Extracellular Signal

Melanocytes are pigmented cells distributed in humans in several organs like the epidermis, the leptomeninges, the eye, and the inner ear. Epidermal melanocytes, whether derived from adult or neonatal skin, proliferate well in a medium supplemented with phorbol esters and other mitogens before they undergo senescence. Potent cAMP inducers like cholera toxin are also growth promoters for neonatal melanocytes but only transient growth stimulators for cells derived from adults. We used this cellular system to delineate biochemical pathways involved in proliferation and in terminal differentiation. Here we show that after a period of 4-8 wk of sustained proliferation in the presence of cholera toxin, the adult melanocytes became round, flat, and enlarged. These changes were associated with terminal growth and preceded by a five- to sixfold increase in cAMP levels and an 8- to 10-fold increase in melanin content. The simultaneous addition of phorbol esters and cholera toxin did not prevent cells from reaching terminal differentiation. Identified targets for phorbol esters are protein kinase C (PKC) and the mitogen-activated kinases (MAPKs), also called extracellular signal-regulated kinases (ERKs). PKC was found to be similarly regulated in proliferating and in terminally differentiated melanocytes. Proliferating melanocytes in early or late passage showed identical activation of the kinase ERK2. This kinase was rapidly phosphorylated upon phorbol 12-myristate 13-acetate (PMA) addition and specifically accumulated in the nucleus of the cells, whereas in unstimulated cells it had a perinuclear distribution. In contrast, senescent and terminally differentiated cells were unable to phosphorylate tyrosine residues of the ERK2 gene product in spite of presenting normal amounts of ERK2 protein. In addition, ERK2 did not show the nuclear accumulation observed in proliferating melanocytes after PMA activation and remained localized in the perinuclear area. These results demonstrate that senescent and terminally differentiated melanocytes share a common block in a critical pathway thought to integrate multiple intracellular signals transmitted by various second messengers and specifically prevent the continuation of the signal transduction cascade initiated by PMA activation of PKC.

scholarly journals Link between Lipid Second Messengers and Osmotic Stress in Plants

2021 ◽  
Vol 22 (5) ◽  
pp. 2658
Author(s):  
Beatriz A. Rodas-Junco ◽  
Graciela E. Racagni-Di-Palma ◽  
Michel Canul-Chan ◽  
Javier Usorach ◽  
S. M. Teresa Hernández-Sotomayor
Keyword(s):  
Osmotic Stress ◽  
Protein Conformation ◽  
Membrane Lipids ◽  
Second Messengers ◽  
Physiological Responses ◽  
Plant Cells ◽  
Transient Molecules ◽  
Molecular Approaches ◽  
Extracellular Signal ◽  
Different Types

Plants are subject to different types of stress, which consequently affect their growth and development. They have developed mechanisms for recognizing and processing an extracellular signal. Second messengers are transient molecules that modulate the physiological responses in plant cells under stress conditions. In this sense, it has been shown in various plant models that membrane lipids are substrates for the generation of second lipid messengers such as phosphoinositide, phosphatidic acid, sphingolipids, and lysophospholipids. In recent years, research on lipid second messengers has been moving toward using genetic and molecular approaches to reveal the molecular setting in which these molecules act in response to osmotic stress. In this sense, these studies have established that second messengers can transiently recruit target proteins to the membrane and, therefore, affect protein conformation, activity, and gene expression. This review summarizes recent advances in responses related to the link between lipid second messengers and osmotic stress in plant cells.

Tamoxifen inhibits phorbol ester stimulated osteoclastic bone resorption: An effect mediated by calmodulin

2000 ◽  
Vol 78 (6) ◽  
pp. 715-723 ◽  
Author(s):  
John P Williams ◽  
Margaret A McKenna ◽  
Allyn M Thames III ◽  
Jay M McDonald
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Bone Resorption ◽  
Phorbol Ester ◽  
Phorbol Esters ◽  
Fold Increase ◽  
Dependent Manner ◽  
Osteoclast Activity ◽  
Kinase C ◽  
Protein Kinase Cα

Tamoxifen inhibits bone resorption by disrupting calmodulin-dependent processes. Since tamoxifen inhibits protein kinase C in other cells, we compared the effects of tamoxifen and the phorbol ester, phorbol myristate acetate, on osteoclast activity. Phorbol esters stimulate bone resorption and calmodulin levels four-fold (k0.5 = 0.1–0.3 µM). In contrast, tamoxifen inhibited osteoclast activity ~60% with an IC50 of 1.5 µM, had no apparent effect on protein kinase C activity in whole-cell lysates, and reduced protein kinase Cα recovered by immunoprecipitation 75%. Phorbol esters stimulated resorption in a time-dependent manner that was closely correlated with a similar-fold increase in calmodulin. Protein kinase Cα, β, δ, ε, and ζ were all down-regulated in response to phorbol ester treatment. Tamoxifen and trifluoperazine inhibited PMA-dependent increases in bone resorption and calmodulin by 85 ± 10%. Down-regulation of protein kinase C isoforms by phorbol esters suggests that the observed increases in bone resorption and calmodulin levels are most likely due to a mechanism independent of protein kinase C and dependent on calmodulin. In conclusion, the data suggest that protein kinase C negatively regulates calmodulin expression and support the hypothesis that the effects of both phorbol esters and tamoxifen on osteoclast activity is mediated by calmodulin.Key words: osteoclast, calmodulin, tamoxifen, osteoporosis, protein kinase C.

Oncogenes, ions, and phospholipids

1985 ◽  
Vol 248 (1) ◽  
pp. C3-C11 ◽  
Author(s):  
I. G. Macara
Keyword(s):  
Cell Proliferation ◽  
Tyrosine Kinases ◽  
Phorbol Esters ◽  
Second Messengers ◽  
Future Research ◽  
Lipid Biochemistry ◽  
Cytosolic Ph ◽  
Pi Turnover ◽  
Transport Studies ◽  
Kinase C

Recent discoveries in tumor virology, lipid biochemistry, and ion transport studies promise to revolutionize our understanding of cell proliferation, differentiation, and tumorigenesis. A model is proposed, based on similar schemes presented recently by others, that incorporates these discoveries and provides a focus for future research on the functions of oncogene proteins. The model suggests that the early (competence) events in the initiation of cell proliferation are triggered by activation of phosphatidylinositol (PI) turnover, which releases two second messengers, 1,2-diacylglycerol (1,2-DG) and inositol-1,4,5-trisphosphate (IP3). PI turnover is proposed to be regulated by the oncogene protein kinases (src, ros, abl, fps) either directly (acting as PI kinases) or indirectly (as tyrosine kinases). The IP3 triggers Ca2+ release from internal stores, and the elevation of cytosolic Ca2+ acts synergistically with 1,2-DG to activate the Ca2+- and phospholipid-dependent kinase C. Kinase C copurifies with the receptor for the tumor-promoting phorbol esters. It is suggested that kinase C then activates the Na+-H+ exchange system, resulting in an elevation of cytosolic pH and Na+, and that these ionic signals (including the change in Ca2+), either in concert or individually, induce further events, including expression of the protooncogene c-myc, which together commit the cell to initiate replication. Evidences in support of this model are reviewed, together with complications indicating its present inadequacies, particularly recent data suggesting that 1,2-DG may activate tyrosine kinases independent of kinase C.

scholarly journals Induced neural differentiation of human mesenchymal stem cells affects lipid metabolism pathways

2021 ◽  
Author(s):  
Pnina Green ◽  
Inna Kan ◽  
Ronit Mesilati-Stahy ◽  
Nurit Argov-Argaman ◽  
Daniel Offen
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Neuronal Development ◽  
Human Mesenchymal Stem Cells ◽  
Fold Increase ◽  
Fatty Acid Binding Proteins ◽  
Prostaglandin E ◽  
Fatty Acid Binding ◽  
Differentiated Cells ◽  
Neuronal Membranes

AbstractNeuronal membranes contain exceptionally high concentrations of long-chain polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and arachidonic acid (ARA), which are essential for neuronal development and function. Adult bone-marrow-derived mesenchymal stem cells (MSC) can be induced to possess some neuronal characteristics. Here we examined the effects of neuronal induction on the PUFA metabolism specific pathways. Differentiated cells contained ~30% less ARA than MSC. The expression of specific ARA metabolizing enzymes was upregulated, notably that of prostaglandin E2 synthase which increased more than 15-fold, concomitantly with a 3-fold increase in the concentration of PGE2 in the medium. Moreover, induced differentiation was associated with enhanced incorporation of exogenous DHA, upregulation of acyl-CoA synthases, fatty acid binding proteins, choline kinase (CK) and phosphatidylserine synthases as well as increased total cellular phospholipids (PL). These findings suggest that active ARA metabolites may be important in the differentiation process and that neuronal induction prepares the resulting cells for increased DHA incorporation through the action of specific enzymes.

scholarly journals Interleukins and IgA synthesis. Human and murine interleukin 6 induce high rate IgA secretion in IgA-committed B cells.

1989 ◽  
Vol 169 (6) ◽  
pp. 2133-2148 ◽  
Author(s):  
K W Beagley ◽  
J H Eldridge ◽  
F Lee ◽  
H Kiyono ◽  
M P Everson ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Sharp Increase ◽  
Plasma Cells ◽  
Terminal Differentiation ◽  
Fold Increase ◽  
High Rate ◽  
Tnf Alpha ◽  
Ifn Gamma ◽  
Ig Synthesis

Freshly isolated murine PP B cells were cultured with 10 different cytokines, including IL-1 alpha, IL-2, IL-4, IL-5, IL-6, IL-7, IFN-gamma, TNF-alpha, and TGF-beta, to investigate a possible role for these cytokines in induction of Ig synthesis. Of interest was the finding that only IL-5 and both mouse recombinant (mr) and human recombinant (hr) IL-6 enhanced IgA synthesis. The effect was greater with either mrIL-6 or hrIL-6 than with mrIL-5. IL-6 induced cycling mIgA+ PP B cells to secrete high levels of IgA (approximately 7-fold increase over control). Of importance was the finding that mrIL-6 had little effect on secretion of IgM or IgG by PP B cell cultures. hrIL-6 also increased IgA secretion by PP B cells and this enhancement was abolished by a goat anti-hrIL-6 antiserum. mrIL-6 did not cause B cell proliferation but induced a sharp increase in numbers of B cells secreting IgA. Isotype-switching was not a mechanism for this marked increase in IgA synthesis since mIgA- PP B cells were not induced to secrete IgA by mrIL-6. From these studies we conclude that IL-6 plays an important role in promoting the terminal differentiation of PP B cells to IgA-secreting plasma cells.

Non-autonomous regulation of a graded, PKA-mediated transcriptional activation signal for cell patterning

Development ◽  
1998 ◽  
Vol 125 (20) ◽  
pp. 3947-3954
Author(s):  
P. Balint-Kurti ◽  
G.T. Ginsburg ◽  
J. Liu ◽  
A.R. Kimmel
Keyword(s):  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Gene Activation ◽  
Distal Segment ◽  
Dominant Negative ◽  
Regulatory Subunit ◽  
Specific Gene ◽  
Differentiated Cells ◽  
Extracellular Signal ◽  
Dependent Protein

The pseudoplasmodium or migrating slug of Dictyostelium is composed of non-terminally differentiated cells, organized along an anteroposterior axis. Cells in the anterior region of the slug define the prestalk compartment, whereas most of the posterior zone consists of prespore cells. We now present evidence that the cAMP-dependent protein kinase (PKA) and the RING domain/leucine zipper protein rZIP interact genetically to mediate a transcriptional activation gradient that regulates the differentiation of prespore cells within the posterior compartment of the slug. PKA is absolutely required for prespore differentiation. In contrast, rZIP negatively regulates prespore patterning; rzpA- cells, which lack rZIP, have reduced prestalk differentiation and a corresponding increase in prespore-specific gene expression. Using cell-specific markers and chimaeras of wild-type and rzpA- cells, we show that rZIP functions non-autonomously to establish a graded, prespore gene activation signal but autonomously to localize prespore expression. Overexpression of either the catalytic subunit or a dominant-negative regulatory subunit of PKA further demonstrates that PKA lies within the intracellular pathway that mediates the extracellular signal and regulates prespore patterning. Finally, we show that a 5′-distal segment within a prespore promoter that is responsive to a graded signal is also sensitive to PKA and rZIP, indicating that it acts directly at the level of prespore-specific gene transcription for regulation.

Expression of p53 during mouse embryogenesis

Development ◽  
1991 ◽  
Vol 113 (3) ◽  
pp. 857-865 ◽  
Author(s):  
P. Schmid ◽  
A. Lorenz ◽  
H. Hameister ◽  
M. Montenarh
Keyword(s):  
Gene Expression ◽  
Cellular Differentiation ◽  
Cellular Proliferation ◽  
In Situ Hybridisation ◽  
Terminal Differentiation ◽  
Mouse Embryogenesis ◽  
Differentiated Cells ◽  
The Brain ◽  
P53 Mrna

By in situ hybridisation we have examined the expression of p53 during mouse embryogenesis from day 8.5 to day 18.5 post coitum (p.c.). High levels of p53 mRNA were detected in all cells of the day 8.5 p.c. and 10.5 p.c. mouse embryo. However, at later stages of development, expression became more pronounced during differentiation of specific tissues e.g. of the brain, liver, lung, thymus, intestine, salivary gland and kidney. In cells undergoing terminal differentiation, the level of p53 mRNA declined strongly. In the brain, hybridisation signals were also observed in postmitotic but not yet terminally differentiated cells. Therefore, gene expression of p53 does not appear to be linked with cellular proliferation in this organ. A proposed role for p53 in cellular differentiation is discussed.

scholarly journals Oxygen pressure-dependent control of carbonic anhydrase synthesis in chick embryonic erythrocytes

1991 ◽  
Vol 261 (5) ◽  
pp. R1188-R1196 ◽  
Author(s):  
D. Million ◽  
P. Zillner ◽  
R. Baumann
Keyword(s):  
Carbonic Anhydrase ◽  
Pertussis Toxin ◽  
Second Messengers ◽  
Fold Increase ◽  
Rapid Onset ◽  
Inhibitor Molecule ◽  
Activation Of Transcription ◽  
Plasma Factor

During chick embryonic development carbonic anhydrase (CA) expression of erythrocytes is kept at a very low level until the last week of incubation (i.e., up to day 14). We have previously obtained evidence that hypoxia is the physiological stimulus for rapid onset of CA synthesis before hatching. Looking for putative signals we have carried out in vitro incubations of embryonic erythrocytes, screening a large number of hormones and second messengers, which were all ineffective, with the exception of the A1 agonist N6-phenylisopropyladenosine (adenosine had no effect). However, incubation with embryonic plasma (10%) from embryos greater than 6 days caused a 10-fold increase of the CA activity during 24 h. This increase was not observed when the incubation was carried out with the addition of actinomycin D, cycloheximide, aluminum fluoride, pertussis toxin, or heat-inactivated plasma. Mammalian plasma had no effect on CA activity. Filtration experiments show that the molecular mass of the factor is less than 2,000 Da. We conclude that embryonic plasma contains a heat-labile factor which stimulates CA synthesis via activation of transcription and whose receptor is coupled to a pertussis toxin-sensitive G protein. In vivo the action of the plasma factor is suppressed as long as blood Po2 is high, suggesting the presence of an inhibitor molecule whose synthesis is controlled by the Po2.

scholarly journals Modulating PKCα Activity to Target Wnt/β-Catenin Signaling in Colon Cancer

Cancers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 693 ◽  
Author(s):  
Sébastien Dupasquier ◽  
Philippe Blache ◽  
Laurence Picque Lasorsa ◽  
Han Zhao ◽  
Jean-Daniel Abraham ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Transcriptional Activity ◽  
Target Genes ◽  
Tumor Development ◽  
Orphan Receptor ◽  
Nuclear Accumulation ◽  
Kinase C ◽  
Extracellular Signal

Inactivating mutations of the tumor suppressor Adenomatosis Polyposis Coli (APC), which are found in familial adenomatosis polyposis and in 80% of sporadic colorectal cancers (CRC), result in constitutive activation of the Wnt/β-catenin pathway and tumor development in the intestine. These mutations disconnect the Wnt/β-catenin pathway from its Wnt extracellular signal by inactivating the APC/GSK3-β/axin destruction complex of β-catenin. This results in sustained nuclear accumulation of β-catenin, followed by β-catenin-dependent co-transcriptional activation of Wnt/β-catenin target genes. Thus, mechanisms acting downstream of APC, such as those controlling β-catenin stability and/or co-transcriptional activity, are attractive targets for CRC treatment. Protein Kinase C-α (PKCα) phosphorylates the orphan receptor RORα that then inhibits β-catenin co-transcriptional activity. PKCα also phosphorylates β-catenin, leading to its degradation by the proteasome. Here, using both in vitro (DLD-1 cells) and in vivo (C57BL/6J mice) PKCα knock-in models, we investigated whether enhancing PKCα function could be beneficial in CRC treatment. We found that PKCα is infrequently mutated in CRC samples, and that inducing PKCα function is not deleterious for the normal intestinal epithelium. Conversely, di-terpene ester-induced PKCα activity triggers CRC cell death. Together, these data indicate that PKCα is a relevant drug target for CRC treatment.

The Identification and Genomic Analysis of microRNAs in Human Erythrocytes in Sickle Cell Diseases.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3400-3400
Author(s):  
Shao-Yin Chen ◽  
Yulei Wang ◽  
Marilyn I. Telen ◽  
Jen-Tsan A. Chi
Keyword(s):  
Microarray Analysis ◽  
Target Gene ◽  
Terminal Differentiation ◽  
Genomic Analysis ◽  
Microrna Expression ◽  
Rt Pcr ◽  
Northern Blots ◽  
Disease Phenotypes ◽  
Differentiated Cells ◽  
The Poor

Abstract Erythrocytes are circulating blood cells responsible for efficient gas exchange in human body. Since mature erythrocytes are terminally differentiated cells without nuclei and organelles, it is commonly thought that they do not contain nucleic acids. In this study, we re-examined this issue and found that human mature erythrocytes, while lacking ribosomal and large-sized RNAs, possess abundant small-sized RNAs. Using a combination of microarray analysis, real-time RT-PCR and Northern blots we found that mature erythrocytes contained abundant and diverse microRNAs which were distinct from microRNAs observed in reticulocytes/leukocytes and contributed to the majority of the microRNA expression in whole blood. When we used microarrays to analyze erythrocytes from normal (HbAA) and homozygous sickle (HbSS) individulas, we noted dramatic a difference in their microRNA expression pattern. To investigate how this difference is associated with erythrocyte disease phenotypes, we found that the poor expression of miR-320 was responsible for the defective downregulation of its target gene CD71 in HbSS cells during terminal differentiation. Collectively, we have discovered significant microRNA expression in human mature erythrocytes, which enables the microarray analysis of erythrocyte property to provide insights into the human erythrocyte diseases.

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