scholarly journals iTRAQ-based proteomic and phosphoproteomic analyses of STRIPAK mutants from the fungus Sordaria macrospora identifies a conserved serine phosphorylation site in PAK kinase CLA4 to be important for sexual development and polarized growth

2019 ◽  
Author(s):  
R Märker ◽  
B Blank-Landeshammer ◽  
A Beier-Rosberger ◽  
A Sickmann ◽  
U Kück
Keyword(s):  
Sexual Development ◽  
Catalytic Domain ◽  
Functional Characterization ◽  
Phosphorylation Site ◽  
Absolute Quantification ◽  
Serine Phosphorylation ◽  
Polarized Growth ◽  
Sordaria Macrospora ◽  
Eukaryotic Microorganisms ◽  
The Impact

SummaryThe highly conserved striatin-interacting phosphatases and kinases (STRIPAK) complex regulates phosphorylation of developmental proteins in eukaryotic microorganisms, animals, and humans. To first identify potential targets of STRIPAK, we performed extensive isobaric tags for relative and absolute quantification (iTRAQ)-based proteomic and phosphoproteomic analyses in the filamentous fungus Sordaria macrospora. In total, we identified 4,193 proteins and 2,489 phosphoproteins, which are represented by 10,635 phosphopeptides. By comparing phosphorylation data from wild-type and mutants, we identified 228 phosphoproteins to be regulated in all three STRIPAK mutants, thus representing potential targets of STRIPAK. To provide an exemplarily functional analysis of a STRIPAK-dependent phosphorylated protein, we selected CLA4, a member of the conserved p21-activated kinase (PAK) family. Functional characterization of the Δcla4 deletion strain showed that CLA4 controls sexual development and polarized growth. To determine the functional relevance of CLA4 phosphorylation and the impact of specific phosphorylation sites on development, we next generated phospho-mimetic and -deficient variants of CLA4. This analysis identified (de)phosphorylation of a highly conserved serine (S685) residue in the catalytic domain of CLA4 as being important for fungal cellular development. Collectively, these analyses significantly contribute to the understanding of the mechanistic function of STRIPAK as a phosphatase and kinase signaling complex.

scholarly journals Phosphoproteomic analysis of STRIPAK mutants identifies a conserved serine phosphorylation site in PAK kinase CLA4 to be important in fungal sexual development and polarized growth

2020 ◽  
Vol 113 (6) ◽  
pp. 1053-1069 ◽  
Author(s):  
Ramona Märker ◽  
Bernhard Blank‐Landeshammer ◽  
Anna Beier‐Rosberger ◽  
Albert Sickmann ◽  
Ulrich Kück
Keyword(s):  
Sexual Development ◽  
Phosphorylation Site ◽  
Serine Phosphorylation ◽  
Polarized Growth ◽  
Pak Kinase

scholarly journals Opposing Effects of Chelidonine on Tyrosine and Serine Phosphorylation of STAT3 in Human Uveal Melanoma Cells

2021 ◽  
Vol 22 (23) ◽  
pp. 12974
Author(s):  
István Csomós ◽  
Péter Nagy ◽  
Csenge Filep ◽  
István Rebenku ◽  
Enikő Nizsalóczki ◽  
...  
Keyword(s):  
Uveal Melanoma ◽  
Nuclear Translocation ◽  
Phosphorylation Site ◽  
Melanoma Cells ◽  
Serine Phosphorylation ◽  
Chelidonium Majus ◽  
Stat3 Phosphorylation ◽  
Partial Overlap ◽  
Opposing Effects ◽  
The Impact

STAT3 is a transcription factor that regulates various cellular processes with oncogenic potential, thereby promoting tumorigenesis when activated uncontrolled. STAT3 activation is mediated by its tyrosine phosphorylation, triggering dimerization and nuclear translocation. STAT3 also contains a serine phosphorylation site, with a postulated regulatory role in STAT3 activation and G2/M transition. Interleukin-6, a major activator of STAT3, is present in elevated concentrations in uveal melanomas, suggesting contribution of dysregulated STAT3 activation to their pathogenesis. Here, we studied the impact of chelidonine on STAT3 signaling in human uveal melanoma cells. Chelidonine, an alkaloid isolated from Chelidonium majus, disrupts microtubules, causes mitotic arrest and provokes cell death in numerous tumor cells. According to our flow cytometry and confocal microscopy data, chelidonine abrogated IL-6-induced activation and nuclear translocation, but amplified constitutive serine phosphorylation of STAT3. Both effects were restricted to a fraction of cells only, in an all-or-none fashion. A partial overlap could be observed between the affected subpopulations; however, no direct connection could be proven. This study is the first proof on a cell-by-cell basis for the opposing effects of a microtubule-targeting agent on the two types of STAT3 phosphorylation.

scholarly journals Protein Kinase C δ Associates with the Interleukin-6 Receptor Subunit Glycoprotein (gp) 130 via Stat3 and Enhances Stat3-gp130 Interaction

2002 ◽  
Vol 277 (51) ◽  
pp. 49134-49142 ◽  
Author(s):  
Veronica Novotny-Diermayr ◽  
Tong Zhang ◽  
Lei Gu ◽  
Xinmin Cao
Keyword(s):  
Protein Kinase ◽  
Catalytic Domain ◽  
Nuclear Translocation ◽  
Phosphorylation Site ◽  
Initial Step ◽  
Dominant Negative ◽  
Serine Phosphorylation ◽  
Dependent Manner ◽  
Transactivation Domain ◽  
Receptor Subunit

The transcriptional regulation of Stat proteins is controlled through their C-terminal domains, which harbor both a tyrosine phosphorylation site, required for dimerization and subsequent nuclear translocation, and a serine phosphorylation site, required for maximum transcriptional activity. Previously, we reported that protein kinase Cδ (PKCδ) phosphorylates and interacts with Stat3 in an interleukin (IL)-6-dependent manner. In this study, we further characterized this interaction, and investigated the potential role of such an interaction. We show here that the catalytic domain of PKCδ interacts with the Src homology 2 domain and part of the adjacent C-terminal transactivation domain of Stat3. This interaction, which does not seem to involve a classical phosphotyrosine SH2-mediated binding, however, significantly enhances the interaction of Stat3 and the IL-6 receptor subunit glycoprotein (gp) 130, which is the initial step for Stat3 activation by IL-6. Expression of a dominant negative PKCδ or depletion of the endogenous PKCδ by phorbol 12-myristate 3-acetate treatment abrogates the association of Stat3 with gp130. At the same time, PKCδ is recruited to gp130 via association with Stat3, which may facilitate its phosphorylation on the gp130 receptor. Finally, we identified Thr-890, a putative PKC phosphorylation site on gp130, to be critical for the effect of PKCδ. Our data indicate that PKCδ plays important regulatory roles in IL-6 signaling.

scholarly journals Targeted Quantification of Phosphorylation Sites Identifies STRIPAK-Dependent Phosphorylation of the Hippo Pathway-Related Kinase SmKIN3

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Valentina Stein ◽  
Bernhard Blank-Landeshammer ◽  
Ramona Märker ◽  
Albert Sickmann ◽  
Ulrich Kück
Keyword(s):  
Phosphorylation Site ◽  
Site Occupancy ◽  
Absolute Quantification ◽  
Time Dependent ◽  
Phosphorylation Sites ◽  
Wild Type ◽  
Content Type ◽  
Sordaria Macrospora ◽  
Septum Formation ◽  
Hyphal Tip

ABSTRACT We showed recently that the germinal center kinase III (GCKIII) SmKIN3 from the fungus Sordaria macrospora is involved in sexual development and hyphal septation. Our recent extensive global proteome and phosphoproteome analysis revealed that SmKIN3 is a target of the striatin-interacting phosphatase and kinase (STRIPAK) multisubunit complex. Here, using protein samples from the wild type and three STRIPAK mutants, we applied absolute quantification by parallel-reaction monitoring (PRM) to analyze phosphorylation site occupancy in SmKIN3 and other septation initiation network (SIN) components, such as CDC7 and DBF2, as well as BUD4, acting downstream of SIN. For SmKIN3, we show that phosphorylation of S668 and S686 is decreased in mutants lacking distinct subunits of STRIPAK, while a third phosphorylation site, S589, was not affected. We constructed SmKIN3 mutants carrying phospho-mimetic and phospho-deficient codons for phosphorylation sites S589, S668, and S686. Investigation of hyphae in a ΔSmkin3 strain complemented by the S668 and S686 mutants showed a hyper-septation phenotype, which was absent in the wild type, the ΔSmkin3 strain complemented with the wild-type gene, and the S589 mutant. Furthermore, localization studies with SmKIN3 phosphorylation variants and STRIPAK mutants showed that SmKIN3 preferentially localizes at the terminal septa, which is distinctly different from the localization of the wild-type strains. We conclude that STRIPAK-dependent phosphorylation of SmKIN3 has an impact on controlled septum formation and on the time-dependent localization of SmKIN3 on septa at the hyphal tip. Thus, STRIPAK seems to regulate SmKIN3, as well as DBF2 and BUD4 phosphorylation, affecting septum formation. IMPORTANCE Phosphorylation and dephosphorylation of proteins are fundamental posttranslational modifications that determine the fine-tuning of their biological activity. Involved in this modification process is the recently identified striatin-interacting phosphatase and kinase (STRIPAK) multisubunit complex, which is evolutionarily conserved from fungi to humans. STRIPAK functions as a macromolecular assembly communicating through physical interactions with other conserved signaling protein complexes to constitute larger dynamic protein networks. Its function is implied in many cellular processes, such as signal transduction pathways, growth, and cellular differentiation. We applied absolute quantification of protein phosphorylation by parallel-reaction monitoring (PRM) to analyze phosphorylation site occupancy in signaling components that are linked to the STRIPAK complex. Using the filamentous fungus Sordaria macrospora, we provide evidence for the phosphorylation-dependent role of the Hippo-like germinal center kinase SmKIN3, which controls septum formation, and localize it in a time-dependent manner on septa at the hyphal tip.

scholarly journals The Arabidopsis Root Tip (Phospho)Proteomes at Growth-Promoting versus Growth-Repressing Conditions Reveal Novel Root Growth Regulators

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1665
Author(s):  
Natalia Nikonorova ◽  
Evan Murphy ◽  
Cassio Flavio Fonseca de Lima ◽  
Shanshuo Zhu ◽  
Brigitte van de Cotte ◽  
...  
Keyword(s):  
Cell Wall ◽  
Root Growth ◽  
Growth Regulators ◽  
Growth Regulation ◽  
Phosphorylation Site ◽  
Primary Root ◽  
Root Tip ◽  
Arabidopsis Root ◽  
Growth Promoting ◽  
The Impact

Auxin plays a dual role in growth regulation and, depending on the tissue and concentration of the hormone, it can either promote or inhibit division and expansion processes in plants. Recent studies have revealed that, beyond transcriptional reprogramming, alternative auxin-controlled mechanisms regulate root growth. Here, we explored the impact of different concentrations of the synthetic auxin NAA that establish growth-promoting and -repressing conditions on the root tip proteome and phosphoproteome, generating a unique resource. From the phosphoproteome data, we pinpointed (novel) growth regulators, such as the RALF34-THE1 module. Our results, together with previously published studies, suggest that auxin, H+-ATPases, cell wall modifications and cell wall sensing receptor-like kinases are tightly embedded in a pathway regulating cell elongation. Furthermore, our study assigned a novel role to MKK2 as a regulator of primary root growth and a (potential) regulator of auxin biosynthesis and signalling, and suggests the importance of the MKK2 Thr31 phosphorylation site for growth regulation in the Arabidopsis root tip.

scholarly journals Co-relation with novel phosphorylation sites of IκBα and necroptosis in breast cancer cells

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sung Hoon Choi ◽  
Hee-Sub Yoon ◽  
Shin-Ae Yoo ◽  
Sung Ho Yun ◽  
Joo-Hee Park ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Phosphorylation Site ◽  
Aurora Kinase ◽  
Serine Phosphorylation ◽  
Flight Mass Spectrometry ◽  
Iκb Kinase ◽  
Orbitrap Mass Spectrometer ◽  
Nf Kappab

Abstract Background Phosphorylation of NF-kappaB inhibitor alpha (IκBα) is key to regulation of NF-κB transcription factor activity in the cell. Several sites of IκBα phosphorylation by members of the IκB kinase family have been identified, but phosphorylation of the protein by other kinases remains poorly understood. We investigated a new phosphorylation site on IκBα and identified its biological function in breast cancer cells. Methods Previously, we observed that aurora kinase (AURK) binds IκBα in the cell. To identify the domains of IκBα essential for phosphorylation by AURK, we performed kinase assays with a series of IκBα truncation mutants. AURK significantly promoted activation of IκBα at serine 32 but not serine 36; by contrast, IκB kinase (IKK) family proteins activated both of these residues. We also confirmed phosphorylation of IκBα by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) and nano-liquid chromatography hybrid quadrupole orbitrap mass spectrometer (nanoLC-MS/MS; Q-Exactive). Results We identified two novel sites of serine phosphorylation, S63 and S262. Alanine substitution of S63 and S262 (S63A and S262A) of IκBα inhibited proliferation and suppressed p65 transcription activity. In addition, S63A and/or S262A of IκBα regulated apoptotic and necroptotic effects in breast cancer cells. Conclusions Phosphorylation of IκBα by AURK at novel sites is related to the apoptosis and necroptosis pathways in breast cancer cells.

scholarly journals POS0352 ALLELIC VARIANTS IN THE ABCG2 GENE CAN LEAD TO HYPERURICEMIA AND GOUT

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 406.2-407
Author(s):  
K. Pavelcova ◽  
J. Bohata ◽  
B. Stiburkova
Keyword(s):  
Uric Acid ◽  
Rare Variants ◽  
Stop Codon ◽  
Functional Characterization ◽  
Premature Stop Codon ◽  
European Population ◽  
Allelic Variants ◽  
Abcg2 Protein ◽  
The Impact ◽  
Abcg2 Gene

Background:The level of uric acid is largely determined by the functions of urate transporters, which are located in the kidney and intestine. The ABCG2 protein is the major excretor of uric acid and its dysfunction may lead to the development of hyperuricemia and gout.Objectives:The aim of our study was to detect the occurrence and frequency of allelic variants in the ABCG2 gene that can lead to impaired function of the ABCG2 protein and to the development of hyperuricemia and gout.Methods:We examined allelic variants of ABCG2 using PCR amplification and Sanger sequencing of all coding regions and exon-intron boundaries in 359 patients with primary hyperuricemia and gout.Results:We found a rare in-frame deletion p.K360del and 15 missense variants, two of which were common (p.V12M, p.Q141K) and 13 were very rare (p.M71V, p.G74D, p.M131I, p.R147W, p.T153M, p.I242T, p.R236X, p.F373C, p.T421A, p.T434M, p.S476P, p.S572R, p.D620N). The p.R236X variant leads to a premature stop codon. The p.V12M variant probably has a protective effect against gout (minor allele frequency – MAF – in our cohort = 0,025 / MAF in the European population = 0,061), while the p.Q141K variant increases the risk of gout (MAF in our cohort = 0,213 / MAF in the European population = 0,094) (1). As for the rare variants, the p.R147W, p.T153M, p.F373C, p.T434M, p.S476P and p.S572R according to functional analyzes reduce the function of the ABCG2 protein (2). Based on in silico prediction, the impact on reduced function is expected for variants p.M71V, p.G74D, p.M131I, p.R147W, p.I242T, p.F373C, p.T434M, p.S476P and p.S572R.Conclusion:Our data suggest that the common variant p.Q141K and most of the rare variants in the ABCG2 gene affect the function of the ABCG2 urate transporter and are a genetic risk factor for hyperuricemia and gout.References:[1]Stiburkova B, et al. Functional non-synonymous variants of ABCG2 and gout risk. Rheumatology (Oxford). 2017 Nov 1; 56(11):1982-1992.[2]Toyoda Y, et al. Functional characterization of clinically-relevant rare variants in ABCG2 identified in a gout and hyperuricemia cohort. Cells. 2019 Apr 18;8(4).Acknowledgements:This study was supported by the project for conceptual development of research organization 00023728 (Institute of Rheumatology) and RVO VFN64165.Disclosure of Interests:None declared

scholarly journals Increased oncogenic potential of ErbB is associated with the loss of a COOH-terminal domain serine phosphorylation site.

1992 ◽  
Vol 267 (12) ◽  
pp. 7967-7970
Author(s):  
S.J. Theroux ◽  
C Taglienti-Sian ◽  
N Nair ◽  
J.L. Countaway ◽  
H.L. Robinson ◽  
...  
Keyword(s):  
Phosphorylation Site ◽  
Serine Phosphorylation ◽  
Oncogenic Potential ◽  
Terminal Domain

scholarly journals The Actin-Binding Protein UNC-115/abLIM Controls Formation of Lamellipodia and Filopodia and Neuronal Morphogenesis in Caenorhabditis elegans

2005 ◽  
Vol 25 (12) ◽  
pp. 5158-5170 ◽  
Author(s):  
Yieyie Yang ◽  
Erik A. Lundquist
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Binding Protein ◽  
Phosphorylation Site ◽  
Serine Phosphorylation ◽  
Actin Binding ◽  
Axon Pathfinding ◽  
Neuronal Morphogenesis ◽  
Actin Binding Protein ◽  
C Elegans

ABSTRACT The roles of actin-binding proteins in development and morphogenesis are not well understood. The actin-binding protein UNC-115 has been implicated in cytoskeletal signaling downstream of Rac in Caenorhabditis elegans axon pathfinding, but the cellular role of UNC-115 in this process remains undefined. Here we report that UNC-115 overactivity in C. elegans neurons promotes the formation of neurites and lamellipodial and filopodial extensions similar to those induced by activated Rac and normally found in C. elegans growth cones. We show that UNC-115 activity in neuronal morphogenesis is enhanced by two molecular mechanisms: when ectopically driven to the plasma membrane by the myristoylation sequence of c-Src, and by mutation of a putative serine phosphorylation site in the actin-binding domain of UNC-115. In support of the hypothesis that UNC-115 modulates actin cytoskeletal organization, we show that UNC-115 activity in serum-starved NIH 3T3 fibroblasts results in the formation of lamellipodia and filopodia. We conclude that UNC-115 is a novel regulator of the formation of lamellipodia and filopodia in neurons, possibly in the growth cone during axon pathfinding.

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