scholarly journals Role of the RNA-binding Protein Nrd1 and Pmk1 Mitogen-activated Protein Kinase in the Regulation of Myosin mRNA Stability in Fission Yeast

2009 ◽  
Vol 20 (9) ◽  
pp. 2473-2485 ◽  
Author(s):  
Ryosuke Satoh ◽  
Takahiro Morita ◽  
Hirofumi Takada ◽  
Ayako Kita ◽  
Shunji Ishiwata ◽  
...  

Myosin II is an essential component of the actomyosin contractile ring and plays a crucial role in cytokinesis by generating the forces necessary for contraction of the actomyosin ring. Cdc4 is an essential myosin II light chain in fission yeast and is required for cytokinesis. In various eukaryotes, the phosphorylation of myosin is well documented as a primary means of activating myosin II, but little is known about the regulatory mechanisms of Cdc4. Here, we isolated Nrd1, an RNA-binding protein with RNA-recognition motifs, as a multicopy suppressor of cdc4 mutants. Notably, we demonstrated that Nrd1 binds and stabilizes Cdc4 mRNA, thereby suppressing the cytokinesis defects of the cdc4 mutants. Importantly, Pmk1 mitogen-activated protein kinase (MAPK) directly phosphorylates Nrd1, thereby negatively regulating the binding activity of Nrd1 to Cdc4 mRNA. Consistently, the inactivation of Pmk1 MAPK signaling, as well as Nrd1 overexpression, stabilized the Cdc4 mRNA level, thereby suppressing the cytokinesis defects associated with the cdc4 mutants. In addition, we demonstrated the cell cycle–dependent regulation of Pmk1/Nrd1 signaling. Together, our results indicate that Nrd1 plays a role in the regulation of Cdc4 mRNA stability; moreover, our study is the first to demonstrate the posttranscriptional regulation of myosin expression by MAPK signaling.

2009 ◽  
Vol 18 (21) ◽  
pp. 4035-4045 ◽  
Author(s):  
Faraz Farooq ◽  
Sylvia Balabanian ◽  
Xuejun Liu ◽  
Martin Holcik ◽  
Alex MacKenzie

2018 ◽  
Vol 48 (4) ◽  
pp. 1747-1754 ◽  
Author(s):  
Yingying Zhang ◽  
Lin Meng ◽  
Lin Xiao ◽  
Ruiwang Liu ◽  
Zhonghai Li ◽  
...  

Background/Aims: Poly r(C) binding protein (PCBP) 1 or heterogeneous ribonucleoprotein (hnRNP) E1 is a RNA binding protein functional in multiple biological processes. In prostate cancer (PCa), PCBP1 loss was shown to be involved with increased stemness in PCacells; however, the underlying mechanism remains unclear. Method: The role of PCBP1 in prostate tumor formationwas determined by xenograft assays. Immunoprecipitationand mass spectrometry were performed to find the pathways altered after PCBP1 knockdown. Cell proliferation, migration, invasion, and soft agar colony formationassays and xenograft assays were used to determine the role of target protein pathogenesis regulation and formation of PCa. QRT-PCR was performedto quantify relative mRNA expression. Results: The expression of mitogen activated protein kinase 1 (MAPK1) or extracellular signal regulated kinase 2 (ERK2) was increased following PCBP1 loss. Attenuation of MAPK1 inhibited in vitro and in vivo tumorigenicity and metastasis in PCa cell line, PC3. Overexpression of MAPK1 in the PC3 cells increased the tumorigenicity and metastasis. Analysis of PCBP1 and MAPK1 mRNA levels in 25 PCa patients compared to tumor-adjacent normal tissue confirmed an inverse correlation between PCBP1 and MAPK1 expression. Conclusions: PCBP1 can act as a suppressor of tumor in prostate epithelial cells by inhibiting MAPK1 expression.


2006 ◽  
Vol 399 (2) ◽  
pp. 265-273 ◽  
Author(s):  
Simon Morton ◽  
Huei-Ting Yang ◽  
Ntsane Moleleki ◽  
David G. Campbell ◽  
Philip Cohen ◽  
...  

A protein in RAW 264.7 macrophages, which became phosphorylated in response to LPS (lipopolysaccharide), was identified as the RNA-binding protein called DAZAP1 [DAZ (deleted in azoospermia)-associated protein 1]. The phosphorylation of this protein was prevented by specific inhibition of MKK1 [MAPK (mitogen-activated protein kinase) kinase 1], indicating that it was phosphorylated via the classical MAPK cascade. Further experiments showed that DAZAP1 was phosphorylated stoichiometrically in vitro by ERK2 (extracellular-signal-regulated protein kinase 2) at two Thr-Pro sequences (Thr269 and Thr315), and that both sites became phosphorylated in HEK-293 (human embryonic kidney 293) cells in response to PMA or EGF (epidermal growth factor), or RAW 264.7 macrophages in response to LPS. Phosphorylation induced by each stimulus was prevented by two structurally distinct inhibitors of MKK1 (PD184352 and U0126), demonstrating that DAZAP1 is a physiological substrate for ERK1/ERK2. The mutation of Thr269 and Thr315 to aspartate or the phosphorylation of these residues caused DAZAP1 to dissociate from its binding partner DAZ. DAZ interacts with PABP [poly(A)-binding protein] and thereby stimulates the translation of mRNAs containing short poly(A) tails [Collier, Gorgoni, Loveridge, Cooke and Gray (2005) EMBO J. 24, 2656–2666]. In the present study we have shown that DAZ cannot bind simultaneously to DAZAP1 and PABP, and suggest that the phosphorylation-induced dissociation of DAZ and DAZAP1 may allow the former to stimulate translation by interacting with PABP.


2010 ◽  
Vol 426 (3) ◽  
pp. 293-306 ◽  
Author(s):  
Peng-Yuan Wang ◽  
Jaladanki N. Rao ◽  
Tongtong Zou ◽  
Lan Liu ◽  
Lan Xiao ◽  
...  

MEK-1 [MAPK (mitogen-activated protein kinase) kinase-1] is an important signal transducing enzyme that is implicated in many aspects of cellular functions. In the present paper, we report that cellular polyamines regulate MEK-1 expression at the post-transcriptional level through the RNA-binding protein HuR (Hu-antigen R) in IECs (intestinal epithelial cells). Decreasing the levels of cellular polyamines by inhibiting ODC (ornithine decarboxylase) stabilized MEK-1 mRNA and promoted its translation through enhancement of the interaction between HuR and the 3′-untranslated region of MEK-1 mRNA, whereas increasing polyamine levels by ectopic ODC overexpression destabilized the MEK-1 transcript and repressed its translation by reducing the abundance of HuR–MEK-1 mRNA complex; neither intervention changed MEK-1 gene transcription via its promoter. HuR silencing rendered the MEK-1 mRNA unstable and inhibited its translation, thus preventing increases in MEK-1 mRNA and protein in polyamine-deficient cells. Conversely, HuR overexpression increased MEK-1 mRNA stability and promoted its translation. Inhibition of MEK-1 expression by MEK-1 silencing or HuR silencing prevented the increased resistance of polyamine-deficient cells to apoptosis. Moreover, HuR overexpression did not protect against apoptosis if MEK-1 expression was silenced. These results indicate that polyamines destabilize the MEK-1 mRNA and repress its translation by inhibiting the association between HuR and the MEK-1 transcript. Our findings indicate that MEK-1 is a key effector of the HuR-elicited anti-apoptotic programme in IECs.


2008 ◽  
Vol 36 (3) ◽  
pp. 491-496 ◽  
Author(s):  
Heike Sandler ◽  
Georg Stoecklin

TTP (tristetraprolin) is an RNA-binding protein that suppresses inflammation by accelerating the degradation of cytokine mRNAs. TTP binds to an AU-rich element in the 3′-untranslated region of its target mRNAs. In macrophages, the induction of cytokine expression requires activation of the p38-MAPK (mitogen-activated protein kinase)–MK2 [MAPKAP (MAPK-activated protein) kinase-2] kinase cascade. MK2 directly phosphorylates TTP and thereby contributes to transient stabilization of cytokine mRNAs. In the present review, we address the target specificity of TTP, summarize TTP-interacting proteins and discuss how phosphorylation regulates the activity, localization and stability of TTP.


2006 ◽  
Vol 17 (12) ◽  
pp. 5028-5037 ◽  
Author(s):  
Yan Ma ◽  
Takayoshi Kuno ◽  
Ayako Kita ◽  
Yuta Asayama ◽  
Reiko Sugiura

We have previously demonstrated that knockout of the calcineurin gene or inhibition of calcineurin activity by immunosuppressants resulted in hypersensitivity to Cl− in fission yeast. We also demonstrated that knockout of the components of the Pmk1 mitogen-activated protein kinase (MAPK) pathway, such as Pmk1 or Pek1 complemented the hypersensitivity to Cl−. Using this interaction between calcineurin and Pmk1 MAPK, here we developed a genetic screen that aims to identify new regulators of the Pmk1 signaling and isolated vic (viable in the presence of immunosuppressant and chloride ion) mutants. One of the mutants, vic1-1, carried a missense mutation in the cpp1+ gene encoding a β subunit of the protein farnesyltransferase, which caused an amino acid substitution of aspartate 155 of Cpp1 to asparagine (Cpp1D155N). Analysis of the mutant strain revealed that Rho2 is a novel target of Cpp1. Moreover, Cpp1 and Rho2 act upstream of Pck2–Pmk1 MAPK signaling pathway, thereby resulting in the vic phenotype upon their mutations. Interestingly, compared with other substrates of Cpp1, defects of Rho2 function were more phenotypically manifested by the Cpp1D155N mutation. Together, our results demonstrate that Cpp1 is a key component of the Pck2–Pmk1 signaling through the spatial control of the small GTPase Rho2.


mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Francisco Prieto-Ruiz ◽  
Jero Vicente-Soler ◽  
Alejandro Franco ◽  
Elisa Gómez-Gil ◽  
Marta Sánchez-Marinas ◽  
...  

ABSTRACT RNA-binding proteins (RBPs) play a major role during control of mRNA localization, stability, and translation and are central to most cellular processes. In the fission yeast Schizosaccharomyces pombe, the multiple K homology (KH) domain RBP Rnc1 downregulates the activity of the cell integrity pathway (CIP) via stabilization of pmp1+ mRNA, which encodes the Pmp1 phosphatase that inactivates Pmk1, the mitogen-activated protein kinase (MAPK) component of this signaling cascade. However, Rnc1 likely regulates the half-life/stability of additional mRNAs. We show that Rnc1 downregulates the activity of Sty1, the MAPK of the stress-activated MAPK pathway (SAPK), during control of cell length at division and recovery in response to acute stress. Importantly, this control strictly depends on Rnc1’s ability to bind mRNAs encoding activators (Wak1 MAPKKK, Wis1 MAPKK) and downregulators (Atf1 transcription factor, Pyp1 and Pyp2 phosphatases) of Sty1 phosphorylation through its KH domains. Moreover, Sty1 is responsible for Rnc1 phosphorylation in vivo at multiple phosphosites during growth and stress, and these modifications trigger Rnc1 for proper binding and destabilization of the above mRNA targets. Phosphorylation by Sty1 prompts Rnc1-dependent mRNA destabilization to negatively control SAPK signaling, thus revealing an additional feedback mechanism that allows precise tuning of MAPK activity during unperturbed cell growth and stress. IMPORTANCE Control of mRNA localization, stability, turnover, and translation by RNA-binding proteins (RBPs) influences essential processes in all eukaryotes, including signaling by mitogen-activated protein kinase (MAPK) pathways. We describe that in the fission yeast Schizosaccharomyces pombe the RBP Rnc1 negatively regulates cell length at division during unperturbed growth and recovery after acute stress by reducing the activity of the MAPK Sty1, which regulates cell growth and differentiation during environmental cues. This mechanism relies on Rnc1 binding to specific mRNAs encoding both enhancers and negative regulators of Sty1 activity. Remarkably, multiple phosphorylation of Rnc1 by Sty1 favors RBP binding and destabilization of the above mRNAs. Thus, posttranscriptional modulation of MAP kinase signaling by RNA-binding proteins emerges as a major regulatory mechanism that dictates the growth cycle and cellular adaptation in response to the changing environment in eukaryotic organisms.


2010 ◽  
Vol 38 (6) ◽  
pp. 1632-1637 ◽  
Author(s):  
Christopher Tiedje ◽  
Alexey Kotlyarov ◽  
Matthias Gaestel

TTP (tristetraprolin) is an RNA-binding protein which regulates mRNA stability or translation or both. The molecular mechanisms which are responsible and which discriminate between regulation of mRNA stability and translation are not completely understood so far, but are clearly dependent on p38 MAPK (mitogen-activated protein kinase)/MK (MAPK-activated protein kinase) 2/3-mediated phosphorylation of TTP. To learn more about these mechanisms, phosphorylation-dependent TTP-interacting proteins could be of great interest. Many interacting partners, which belong to the mRNA-processing and -regulating machinery, have been identified by hypothesis-driven co-immunoprecipitation and in the classical Y2H (yeast two-hybrid) approach, where TTP was identified as prey, and are summarized in the present paper. However, because of transactivating properties of TTP, an unbiased Y2H approach using TTP as bait was hindered. Since novel methods for the identification of phosphorylation-dependent interaction partners and of interactors of full-length auto-activating proteins in eukaryotic systems have evolved in the last few years, these methods should be applied to screen for additional phosphorylation-dependent interaction partners of TTP and could lead towards a complete understanding of TTP function at the molecular level.


2018 ◽  
Vol 29 (10) ◽  
pp. 1157-1167 ◽  
Author(s):  
Laurel M. Oldach ◽  
Kirill Gorshkov ◽  
William T. Mills ◽  
Jin Zhang ◽  
Mollie K. Meffert

Intracellular levels of the RNA-binding protein and pluripotency factor, Lin28a, are tightly controlled to govern cellular and organismal growth. Lin28a is extensively regulated at the posttranscriptional level, and can undergo mitogen-activated protein kinase (MAPK)–mediated elevation from low basal levels in differentiated cells by phosphorylation-dependent stabilizing interaction with the RNA-silencing factor HIV TAR RNA-binding protein (TRBP). However, molecular and spatiotemporal details of this critical control mechanism remained unknown. In this work, we dissect the interacting regions of Lin28a and TRBP proteins and develop biosensors to visualize this interaction. We identify truncated domains of Lin28a and of TRBP that are sufficient to support coassociation and mutual elevation of protein levels, and a requirement for MAPK-dependent phosphorylation of TRBP at putative Erk-target serine 152, as well as Lin28a serine 200 phosphorylation, in mediating the increase of Lin28a protein by TRBP. The phosphorylation-dependent association of Lin28a and TRBP truncated constructs is leveraged to develop fluorescence resonance energy transfer (FRET)-based sensors for dynamic monitoring of Lin28a and TRBP interaction. We demonstrate the response of bimolecular and unimolecular FRET sensors to growth factor stimulation in living cells, with coimaging of Erk activation to achieve further understanding of the role of MAPK signaling in Lin28a regulation.


2007 ◽  
Vol 18 (12) ◽  
pp. 4794-4802 ◽  
Author(s):  
Hirofumi Takada ◽  
Masayuki Nishimura ◽  
Yuta Asayama ◽  
Yoshiaki Mannse ◽  
Shunji Ishiwata ◽  
...  

In fission yeast, knockout of the calcineurin gene resulted in hypersensitivity to Cl−, and the overexpression of pmp1+ encoding a dual-specificity phosphatase for Pmk1 mitogen-activated protein kinase (MAPK) or the knockout of the components of the Pmk1 pathway complemented the Cl− hypersensitivity of calcineurin deletion. Here, we showed that the overexpression of ptc1+ and ptc3+, both encoding type 2C protein phosphatase (PP2C), previously known to inactivate the Wis1–Spc1–Atf1 stress-activated MAPK signaling pathway, suppressed the Cl− hypersensitivity of calcineurin deletion. We also demonstrated that the mRNA levels of these two PP2Cs and pyp2+, another negative regulator of Spc1, are dependent on Pmk1. Notably, the deletion of Atf1, but not that of Spc1, displayed hypersensitivity to the cell wall-damaging agents and also suppressed the Cl− hypersensitivity of calcineurin deletion, both of which are characteristic phenotypes shared by the mutation of the components of the Pmk1 MAPK pathway. Moreover, micafungin treatment induced Pmk1 hyperactivation that resulted in Atf1 hyperphosphorylation. Together, our results suggest that PP2C is involved in a negative feedback loop of the Pmk1 signaling, and results also demonstrate that Atf1 is a key component of the cell integrity signaling downstream of Pmk1 MAPK.


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