Activating Mutations in PTPN11 and KRAS in Canine Histiocytic Sarcomas

While the genetic contributions to the predisposition of Bernese mountain dogs (BMDs) to histiocytic sarcoma (HS) remains unclear, some insights into key genetic drivers have been gained. Our group recently reported a mutation in the PTPN11 gene (E76K). We have now identified a second missense mutation in PTPN11 (G503V), and a mutation in KRAS (Q61H) present in HS cell lines. These mutations are associated with malignancies in humans, and known to be gain-of-function mutations that result in activation of the mitogen-activated protein kinase (MAPK) pathway. The goal of the present study was to evaluate the prevalence of these mutations in a large sample of HS cases from BMDs and golden retrievers, and in lymphoma cases, from a cohort of BMDs. Mutations in PTPN11 were present in HS in 41/96 (43%) BMDs, and in 3/13 (23%) golden retrievers. PTPN11 mutations E76K and G503V did not coexist in the same neoplasm. The KRAS mutation was much less frequent, with a prevalence of 3.1% (3/96). We did not identify either PTPN11 nor KRAS mutations in any of the lymphoma samples. These results point out the potential relevance of PTPN11 and KRAS mutations as activators of the oncogenic MAPK pathway for canine HS, particularly in BMDs.

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Isoform-Specific Ras Activation and Oncogene Dependence during MYC- and Wnt-Induced Mammary Tumorigenesis

Molecular and Cellular Biology ◽

10.1128/mcb.00404-06 ◽

2006 ◽

Vol 26 (21) ◽

pp. 8109-8121 ◽

Cited By ~ 40

Author(s):

Joanne W. Jang ◽

Robert B. Boxer ◽

Lewis A. Chodosh

Keyword(s):

Protein Kinase ◽

Tumor Growth ◽

Mapk Pathway ◽

Mammary Tumorigenesis ◽

Mitogen Activated Protein Kinase ◽

Activating Mutations ◽

Ras Activation ◽

Pathway Activation ◽

Induced Tumors ◽

Mitogen Activated Protein

ABSTRACT We have previously shown that c-MYC-induced mammary tumorigenesis in mice proceeds via a preferred secondary pathway involving spontaneous activating mutations in Kras2 (C. M. D'Cruz, E. J. Gunther, R. B. Boxer, J. L. Hartman, L. Sintasath, S. E. Moody, J. D. Cox, S. I. Ha, G. K. Belka, A. Golant, R. D. Cardiff, and L. A. Chodosh, Nat. Med. 7:235-239, 2001). In contrast, we now demonstrate that Wnt1-induced mammary tumorigenesis proceeds via a pathway that preferentially activates Hras1. In addition, we find that expression of oncogenic forms of Kras2 and Hras1 from their endogenous promoters has markedly different consequences for the progression of tumors to oncogene independence. Spontaneous activating Kras2 mutations occurring in either MYC- or Wnt1-induced tumors were strongly associated with oncogene-independent tumor growth following MYC or Wnt1 downregulation. In contrast, Hras1-mutant Wnt1-induced tumors consistently remained oncogene dependent. Additionally, Kras2-mutant tumors exhibited substantially higher levels of ras-GTP, phospho-Erk1/2, and phospho-Mek1/2 compared to Hras1-mutant tumors, suggesting the involvement of the ras/mitogen-activated protein kinase (MAPK) pathway in the acquisition of oncogene independence. Consistent with this, by use of carcinogen-induced ras mutations as well as knock-in mice harboring a latent activated Kras2 allele, we demonstrate that Kras2 activation strongly synergizes with both c-MYC and Wnt1 in mammary tumorigenesis and promotes the progression of tumors to oncogene independence. Together, our findings support a model for tumorigenesis in which c-MYC and Wnt1 select for the outgrowth of cells harboring mutations in specific ras isoforms and that these secondary mutations, in turn, determine the extent of ras/MAPK pathway activation and the potential for oncogene-independent growth.

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Expression of transgenes enriched in rare codons is enhanced by the MAPK pathway

Scientific Reports ◽

10.1038/s41598-020-78453-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Jackson Peterson ◽

Siqi Li ◽

Erin Kaltenbrun ◽

Ozgun Erdogan ◽

Christopher M. Counter

Keyword(s):

Amino Acids ◽

Protein Kinase ◽

Mapk Pathway ◽

Mitogen Activated Protein Kinase ◽

Rare Codons ◽

Synonymous Codons ◽

Multiple Components ◽

Human Genes ◽

Regulatory Module ◽

Mitogen Activated Protein

AbstractThe ability to translate three nucleotide sequences, or codons, into amino acids to form proteins is conserved across all organisms. All but two amino acids have multiple codons, and the frequency that such synonymous codons occur in genomes ranges from rare to common. Transcripts enriched in rare codons are typically associated with poor translation, but in certain settings can be robustly expressed, suggestive of codon-dependent regulation. Given this, we screened a gain-of-function library for human genes that increase the expression of a GFPrare reporter encoded by rare codons. This screen identified multiple components of the mitogen activated protein kinase (MAPK) pathway enhancing GFPrare expression. This effect was reversed with inhibitors of this pathway and confirmed to be both codon-dependent and occur with ectopic transcripts naturally coded with rare codons. Finally, this effect was associated, at least in part, with enhanced translation. We thus identify a potential regulatory module that takes advantage of the redundancy in the genetic code to modulate protein expression.

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Ghrelin exerts a proliferative effect on a rat pituitary somatotroph cell line via the mitogen-activated protein kinase pathway

Acta Endocrinologica ◽

10.1530/eje.0.1510233 ◽

2004 ◽

pp. 233-240 ◽

Cited By ~ 99

Author(s):

AM Nanzer ◽

S Khalaf ◽

AM Mozid ◽

RC Fowkes ◽

MV Patel ◽

...

Keyword(s):

Cell Proliferation ◽

Protein Kinase ◽

Cell Line ◽

Kinase Inhibitor ◽

Thymidine Incorporation ◽

Mapk Pathway ◽

Mitogen Activated Protein Kinase ◽

Gh3 Cells ◽

Rat Pituitary ◽

Mitogen Activated Protein

OBJECTIVES: Ghrelin is a brain-gut peptide with GH-releasing and appetite-inducing activities and a widespread tissue distribution. Ghrelin is the endogenous ligand of the GH secretagogue receptor type 1a (GHS-R1a), and both ghrelin and the GHS-R1a are expressed in the pituitary. There are conflicting data regarding the effects of ghrelin on cell proliferation. A positive effect on proliferation and activation of the mitogen-activated protein kinase (MAPK) pathway has been found in hepatoma, adipose, cardiomyocyte and prostate cell lines. However, ghrelin has also been shown to have anti-proliferative effects on breast, lung and thyroid cell lines. We therefore examined the effect of ghrelin on the rat pituitary cell line GH3. METHODS: RT-PCR was used for the detection of GHS-R1a and pre-proghrelin mRNA expression in GH3 cells. The effect of ghrelin on cell proliferation was studied using [(3)H]thymidine incorporation; cell counting and the activation of the MAPK pathway were studied using immunoblotting and inhibitors of the extracellular signal-regulated kinase 1 and 2 (ERK 1/2), protein kinase C (PKC) and tyrosine phosphatase pathways. RESULTS: GHS-R1a and ghrelin mRNA expression were detected in GH3 cells. Ghrelin, at 10(-10) to 10(-6) M concentrations, significantly increased [(3)H]thymidine incorporation (at 10(-9) M, 183+/-13% (means+/-s.e.m.) compared with untreated controls), while 12-phorbol 13-myristate acetate (PMA) at 10(-7) M (used as a positive control) caused a 212+/-14% increase. A reproducible stimulatory effect of desoctanoyl ghrelin was also observed on [(3)H]thymidine incorporation (135+/-5%; P<0.01 at 10(-9) M compared with control), as well as on the cell count (control 6.8 x 10(4)+/-8.7 x 10(3) cells/ml vs desoctanoyl ghrelin (10(-9) M) 1.04 x 10(5)+/-7.5 x 10(3) cells/ml; P<0.01). Ghrelin caused a significant increase in phosphorylated ERK 1/2 in immunoblotting, while desoctanoyl ghrelin showed a smaller but also significant stimulatory effect. The positive effect of ghrelin and desoctanoyl ghrelin on [(3)H]thymidine incorporation was abolished by the MAPK kinase inhibitor U0126, the PKC inhibitor GF109203X and the tyrosine kinase inhibitor tyrphostin 23, suggesting that the ghrelin-induced cell proliferation of GH3 cells is mediated both via a PKC-MAPK-dependent pathway and via a tyrosine kinase-dependent pathway. This could also be clearly demonstrated by Western blot analysis, where a transient increase in ERK 1/2 phosphorylation by ghrelin was attenuated by all three inhibitors. CONCLUSION: We have shown a novel role for ghrelin in stimulating the proliferation of a somatotroph pituitary tumour cell line, suggesting that ERK activation is involved in mediating the effects of ghrelin on cell proliferation. Desoctanoyl ghrelin showed a similar effect. As ghrelin has been shown to be expressed in both normal and adenomatous pituitary tissue, locally produced ghrelin may play a role in pituitary tumorigenesis via an autocrine/paracrine pathway.

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The vaccinia virus-stimulated mitogen-activated protein kinase (MAPK) pathway is required for virus multiplication

Biochemical Journal ◽

10.1042/bj20031375 ◽

2004 ◽

Vol 381 (2) ◽

pp. 437-446 ◽

Cited By ~ 96

Author(s):

Anderson A. ANDRADE ◽

Patrícia N. G. SILVA ◽

Anna C. T. C. PEREIRA ◽

Lirlândia P. de SOUSA ◽

Paulo C. P. FERREIRA ◽

...

Keyword(s):

Protein Kinase ◽

Tyrosine Kinase ◽

Vaccinia Virus ◽

Mapk Pathway ◽

Decisive Role ◽

Virus Multiplication ◽

Mitogen Activated Protein Kinase ◽

Actin Dynamics ◽

Kinase Activation ◽

Mitogen Activated Protein

Early events play a decisive role in virus multiplication. We have shown previously that activation of MAPK/ERK1/2 (mitogen-activated protein kinase/extracellular-signal-regulated kinase 1/2) and protein kinase A are pivotal for vaccinia virus (VV) multiplication [de Magalhães, Andrade, Silva, Sousa, Ropert, Ferreira, Kroon, Gazzinelli and Bonjardim (2001) J. Biol. Chem. 276, 38353–38360]. In the present study, we show that VV infection provoked a sustained activation of both ERK1/2 and RSK2 (ribosomal S6 kinase 2). Our results also provide evidence that this pattern of kinase activation depends on virus multiplication and ongoing protein synthesis and is maintained independently of virus DNA synthesis. It is noteworthy that the VGF (VV growth factor), although involved, is not essential for prolonged ERK1/2 activation. Furthermore, our findings suggest that the VV-stimulated ERK1/2 activation also seems to require actin dynamics, microtubule polymerization and tyrosine kinase phosphorylation. The VV-stimulated pathway MEK/ERK1/2/RSK2 (where MEK stands for MAPK/ERK kinase) leads to phosphorylation of the ternary complex factor Elk-1 and expression of the early growth response (egr-1) gene, which kinetically paralleled the kinase activation. The recruitment of this pathway is biologically relevant, since its disruption caused a profound effect on viral thymidine kinase gene expression, viral DNA replication and VV multiplication. This pattern of sustained kinase activation after VV infection is unique. In addition, by connecting upstream signals generated at the cytoskeleton and by tyrosine kinase, the MEK/ERK1/2/RSK2 cascade seems to play a decisive role not only at early stages of the infection, i.e. post-penetration, but is also crucial to define the fate of virus progeny.

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APPL1 mediates adiponectin-stimulated p38 MAPK activation by scaffolding the TAK1-MKK3-p38 MAPK pathway

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00427.2010 ◽

2011 ◽

Vol 300 (1) ◽

pp. E103-E110 ◽

Cited By ~ 59

Author(s):

Xiaoban Xin ◽

Lijun Zhou ◽

Caleb M. Reyes ◽

Feng Liu ◽

Lily Q. Dong

Keyword(s):

Protein Kinase ◽

P38 Mapk ◽

Mapk Pathway ◽

Adaptor Protein ◽

Mapk Signaling ◽

Mitogen Activated Protein Kinase ◽

Scaffolding Protein ◽

Mapk Activation ◽

P38 Mapk Pathway ◽

Mitogen Activated Protein

The adaptor protein APPL1 mediates the stimulatory effect of adiponectin on p38 mitogen-activated protein kinase (MAPK) signaling, yet the underlying mechanism remains unclear. Here we show that, in C2C12 cells, overexpression or suppression of APPL1 enhanced or suppressed, respectively, adiponectin-stimulated p38 MAPK upstream kinase cascade, consisting of transforming growth factor-β-activated kinase 1 (TAK1) and mitogen-activated protein kinase kinase 3 (MKK3). In vitro affinity binding and coimmunoprecipitation experiments revealed that TAK1 and MKK3 bind to different regions of APPL1, suggesting that APPL1 functions as a scaffolding protein to facilitate adiponectin-stimulated p38 MAPK activation. Interestingly, suppressing APPL1 had no effect on TNFα-stimulated p38 MAPK phosphorylation in C2C12 myotubes, indicating that the stimulatory effect of APPL1 on p38 MAPK activation is selective. Taken together, our study demonstrated that the TAK1-MKK3 cascade mediates adiponectin signaling and uncovers a scaffolding role of APPL1 in regulating the TAK1-MKK3-p38 MAPK pathway, specifically in response to adiponectin stimulation.

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Both Binding and Activation of p38 Mitogen-Activated Protein Kinase (MAPK) Play Essential Roles in Regulation of the Nucleocytoplasmic Distribution of MAPK-Activated Protein Kinase 5 by Cellular Stress

Molecular and Cellular Biology ◽

10.1128/mcb.22.20.6931-6945.2002 ◽

2002 ◽

Vol 22 (20) ◽

pp. 6931-6945 ◽

Cited By ~ 61

Author(s):

Ole Morten Seternes ◽

Bjarne Johansen ◽

Beate Hegge ◽

Mona Johannessen ◽

Stephen M. Keyse ◽

...

Keyword(s):

Protein Kinase ◽

P38 Mapk ◽

Nuclear Export ◽

Fluorescent Protein ◽

Mapk Pathway ◽

Nuclear Export Signal ◽

Mitogen Activated Protein Kinase ◽

Protein Fusion ◽

Translational Machinery ◽

Mitogen Activated Protein

ABSTRACT The p38 mitogen-activated protein kinase (MAPK) pathway is an important mediator of cellular responses to environmental stress. Targets of p38 include transcription factors, components of the translational machinery, and downstream serine/threonine kinases, including MAPK-activated protein kinase 5 (MK5). Here we have used enhanced green fluorescent protein fusion proteins to analyze the subcellular localization of MK5. Although this protein is predominantly nuclear in unstimulated cells, MK5 shuttles between the nucleus and the cytoplasm. Furthermore, we have shown that the C-terminal domain of MK5 contains both a functional nuclear localization signal (NLS) and a leucine-rich nuclear export signal (NES), indicating that the subcellular distribution of this kinase reflects the relative activities of these two signals. In support of this, we have shown that stress-induced activation of the p38 MAPK stimulates the chromosomal region maintenance 1 protein-dependent nuclear export of MK5. This is regulated by both binding of p38 MAPK to MK5, which masks the functional NLS, and stress-induced phosphorylation of MK5 by p38 MAPK, which either activates or unmasks the NES. These properties may define the ability of MK5 to differentially phosphorylate both nuclear and cytoplasmic targets or alternatively reflect a mechanism whereby signals initiated by activation of MK5 in the nucleus may be transmitted to the cytoplasm.

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