-
Molecular Cancer Sep 2023The Eyes Absent (EYA) family of proteins is an atypical group of four dual-functioning protein phosphatases (PP), which have been linked to many vital cellular processes...
The Eyes Absent (EYA) family of proteins is an atypical group of four dual-functioning protein phosphatases (PP), which have been linked to many vital cellular processes and organogenesis pathways. The four family members of this PP family possess transcriptional activation and phosphatase functions, with serine/threonine and tyrosine phosphatase domains. EYA4 has been associated with several human cancers, with tumor-suppressing and tumor-promoting roles. However, EYA4 is the least well-characterized member of this unique family of PP, with its biological functions and molecular mechanisms in cancer progression, particularly in breast cancer, still largely unknown. In the present study, we found that the over-expression of EYA4 in breast tissue leads to an aggressive and invasive breast cancer phenotype, while the inhibition of EYA4 reduced tumorigenic properties of breast cancer cells in vitro and in vivo. Cellular changes downstream of EYA4, including cell proliferation and migration, may explain the increased metastatic power of breast cancer cells over-expressing EYA4. Mechanistically, EYA4 prevents genome instability by inhibiting the accumulation of replication-associated DNA damage. Its depletion results in polyploidy as a consequence of endoreplication, a phenomenon that can occur in response to stress. The absence of EYA4 leads to spontaneous replication stress characterized by the activation of the ATR pathway, sensitivity to hydroxyurea, and accumulation of endogenous DNA damage as indicated by increased γH2AX levels. In addition, we show that EYA4, specifically its serine/threonine phosphatase domain, plays an important and so far, unexpected role in replication fork progression. This phosphatase activity is essential for breast cancer progression and metastasis. Taken together, our data indicate that EYA4 is a novel potential breast cancer oncogene that supports primary tumor growth and metastasis. Developing therapeutics aimed at the serine/threonine phosphatase activity of EYA4 represents a robust strategy for killing breast cancer cells, to limit metastasis and overcome chemotherapy resistance caused by endoreplication and genomic rearrangements.
Topics: Humans; Female; Breast Neoplasms; Trans-Activators; Cell Line, Tumor; Protein Tyrosine Phosphatases; Phosphoprotein Phosphatases; Serine
PubMed: 37777742
DOI: 10.1186/s12943-023-01861-4 -
Toxins Oct 2020Cyanobacterial harmful algal blooms (CyanoHABs) produce microcystins (MCs) which are associated with animal and human hepatotoxicity. Over 270 variants of MC exist. MCs... (Review)
Review
Cyanobacterial harmful algal blooms (CyanoHABs) produce microcystins (MCs) which are associated with animal and human hepatotoxicity. Over 270 variants of MC exist. MCs have been continually studied due of their toxic consequences. Monitoring water quality to assess the presence of MCs is of utmost importance although it is often difficult because CyanoHABs may generate multiple MC variants, and their low concentration in water. To effectively manage and control these toxins and prevent their health risks, sensitive, fast, and reliable methods capable of detecting MCs are required. This paper aims to review the three main analytical methods used to detect MCs ranging from biological (mouse bioassay), biochemical (protein phosphatase inhibition assay and enzyme linked immunosorbent assay), and chemical (high performance liquid chromatography, liquid chromatography-mass spectrometry, high performance capillary electrophoresis, and gas chromatography), as well as the newly emerging biosensor methods. In addition, the current state of these methods regarding their novel development and usage, as well as merits and limitations are presented. Finally, this paper also provides recommendations and future research directions towards method application and improvement.
Topics: Animals; Biological Assay; Biosensing Techniques; Chromatography; Cyanobacteria; Environmental Monitoring; Enzyme Inhibitors; Harmful Algal Bloom; Lethal Dose 50; Mass Spectrometry; Mice; Microcystins; Phosphoprotein Phosphatases; Reproducibility of Results; Water Microbiology; Water Pollutants, Chemical
PubMed: 33020400
DOI: 10.3390/toxins12100641 -
Progress in Neurobiology Mar 2021The dual-specificity phosphatase (DUSP) family includes a heterogeneous group of protein phosphatases that dephosphorylate both phospho-tyrosine and... (Review)
Review
The dual-specificity phosphatase (DUSP) family includes a heterogeneous group of protein phosphatases that dephosphorylate both phospho-tyrosine and phospho-serine/phospho-threonine residues within a single substrate. These protein phosphatases have many substrates and modulate diverse neural functions, such as neurogenesis, differentiation, and apoptosis. DUSP genes have furthermore been associated with mental disorders such as depression and neurological disorders such as Alzheimer's disease. Herein, we review the current literature on the DUSP family of genes concerning mental and neurological disorders. This review i) outlines the structure and general functions of DUSP genes, and ii) overviews the literature on DUSP genes concerning mental and neurological disorders, including model systems, while furthermore providing perspectives for future research.
Topics: Dual-Specificity Phosphatases; Humans; Nervous System Diseases; Neurogenesis; Phosphoprotein Phosphatases
PubMed: 32905807
DOI: 10.1016/j.pneurobio.2020.101906 -
Nature Communications Feb 2023MYC-driven medulloblastomas are highly aggressive childhood brain tumors, however, the molecular and genetic events triggering MYC amplification and malignant...
MYC-driven medulloblastomas are highly aggressive childhood brain tumors, however, the molecular and genetic events triggering MYC amplification and malignant transformation remain elusive. Here we report that mutations in CTDNEP1, a CTD nuclear-envelope-phosphatase, are the most significantly enriched recurrent alterations in MYC-driven medulloblastomas, and define high-risk subsets with poorer prognosis. Ctdnep1 ablation promotes the transformation of murine cerebellar progenitors into Myc-amplified medulloblastomas, resembling their human counterparts. CTDNEP1 deficiency stabilizes and activates MYC activity by elevating MYC serine-62 phosphorylation, and triggers chromosomal instability to induce p53 loss and Myc amplifications. Further, phosphoproteomics reveals that CTDNEP1 post-translationally modulates the activities of key regulators for chromosome segregation and mitotic checkpoint regulators including topoisomerase TOP2A and checkpoint kinase CHEK1. Co-targeting MYC and CHEK1 activities synergistically inhibits CTDNEP1-deficient MYC-amplified tumor growth and prolongs animal survival. Together, our studies demonstrate that CTDNEP1 is a tumor suppressor in highly aggressive MYC-driven medulloblastomas by controlling MYC activity and mitotic fidelity, pointing to a CTDNEP1-dependent targetable therapeutic vulnerability.
Topics: Humans; Mice; Animals; Child; Medulloblastoma; Phosphoric Monoester Hydrolases; Cerebellar Neoplasms; Brain Neoplasms; Cell Transformation, Neoplastic; Genomic Instability; Proto-Oncogene Proteins c-myc; Phosphoprotein Phosphatases
PubMed: 36765089
DOI: 10.1038/s41467-023-36400-8 -
Molekuliarnaia Biologiia 2021Small SCP phosphatases CTDSP1, CTDSP2, and CTDSPL specifically dephosphorylate serine and threonine residues in protein molecules. The enzymes are involved in regulating... (Review)
Review
Small SCP phosphatases CTDSP1, CTDSP2, and CTDSPL specifically dephosphorylate serine and threonine residues in protein molecules. The enzymes are involved in regulating activity of RNA polymerase II at the transition from transcription initiation to elongation, regulating expression of neuron-specific genes, and activating the key cell-cycle protein pRb at the G1/S boundary. In addition, the substrates of SCP phosphatases include SMAD transcription modulators; AKT1 protein kinase, which regulates the cell cycle, apoptosis, and angiogenesis; the TWIST1 and c-MYC transcription factors; Ras family proteins, which are involved in signaling pathways regulating the cell growth and apoptosis; CDCA3, which is associated with cell division; the cyclin-dependent kinase inhibitor p21; and the promyelocytic leukemia protein (PML), which is involved in regulation of the tumor suppressors p53, PTEN, and mTOR. Dysfunction or inactivation of SCP phosphatases leads to various diseases, including cancer. Recently the increase in interest to SCP phosphatases is due to their their tumor growth-inhibiting properties or role in the development of malignant tumors of various etiology and localization. The review discusses the properties of SCP phosphatases and their role in oncogenesis. Understanding the functions of SCP phosphatases and their regulatory mechanisms can be useful in searching for efficient targets for tumor therapy.
Topics: Carcinogenesis; Cell Cycle; Cell Cycle Proteins; Cell Transformation, Neoplastic; Humans; Neoplasms; Phosphoprotein Phosphatases
PubMed: 34432772
DOI: 10.31857/S0026898421040091 -
JCI Insight Feb 2023TGF-β signaling is crucial for modulating osteoarthritis (OA), and protein phosphatase magnesium-dependent 1A (PPM1A) has been reported as a phosphatase of SMAD2 and...
TGF-β signaling is crucial for modulating osteoarthritis (OA), and protein phosphatase magnesium-dependent 1A (PPM1A) has been reported as a phosphatase of SMAD2 and regulates TGF-β signaling, while the role of PPM1A in cartilage homeostasis and OA development remains largely unexplored. In this study, we found increased PPM1A expression in OA chondrocytes and confirmed the interaction between PPM1A and phospho-SMAD2 (p-SMAD2). Importantly, our data show that PPM1A KO substantially protected mice treated with destabilization of medial meniscus (DMM) surgery against cartilage degeneration and subchondral sclerosis. Additionally, PPM1A ablation reduced the cartilage catabolism and cell apoptosis after the DMM operation. Moreover, p-SMAD2 expression in chondrocytes from KO mice was higher than that in WT controls with DMM induction. However, intraarticular injection with SD-208, repressing TGF-β/SMAD2 signaling, dramatically abolished protective phenotypes in PPM1A-KO mice. Finally, a specific pharmacologic PPM1A inhibitor, Sanguinarine chloride (SC) or BC-21, was able to ameliorate OA severity in C57BL/6J mice. In summary, our study identified PPM1A as a pivotal regulator of cartilage homeostasis and demonstrated that PPM1A inhibition attenuates OA progression via regulating TGF-β/SMAD2 signaling in chondrocytes and provided PPM1A as a potential target for OA treatment.
Topics: Animals; Mice; Chondrocytes; Mice, Inbred C57BL; Osteoarthritis; Phosphoprotein Phosphatases; Protein Phosphatase 2C; Signal Transduction; Transforming Growth Factor beta; Smad2 Protein
PubMed: 36752205
DOI: 10.1172/jci.insight.166688 -
Cellular Signalling Feb 2022Reversible phosphorylation of ion channels and calcium-handling proteins provides precise post-translational regulation of cardiac excitation and contractility.... (Review)
Review
Reversible phosphorylation of ion channels and calcium-handling proteins provides precise post-translational regulation of cardiac excitation and contractility. Serine/threonine phosphatases govern dephosphorylation of the majority of cardiac proteins. Accordingly, dysfunction of this regulation contributes to the development and progression of heart failure and atrial fibrillation. On the molecular level, these changes include alterations in the expression level and phosphorylation status of Ca handling and excitation-contraction coupling proteins provoked by dysregulation of phosphatases. The serine/threonine protein phosphatase PP1 is one a major player in the regulation of cardiac excitation-contraction coupling. PP1 essentially impacts on cardiac physiology and pathophysiology via interactions with the cardiac ion channels Cav1.2, NKA, NCX and KCNQ1, sarcoplasmic reticulum-bound Ca handling proteins such as RyR2, SERCA and PLB as well as the contractile proteins MLC2, TnI and MyBP-C. PP1 itself but also PP1-regulatory proteins like inhibitor-1, inhibitor-2 and heat-shock protein 20 are dysregulated in cardiac disease. Therefore, they represent interesting targets to gain more insights in heart pathophysiology and to identify new treatment strategies for patients with heart failure or atrial fibrillation. We describe the genetic and holoenzymatic structure of PP1 and review its role in the heart and cardiac disease. Finally, we highlight the importance of the PP1 regulatory proteins for disease manifestation, provide an overview of genetic models to study the role of PP1 for the development of heart failure and atrial fibrillation and discuss possibilities of pharmacological interventions.
Topics: Calcium; Heart; Heart Failure; Humans; Phosphoprotein Phosphatases; Phosphorylation; Protein Phosphatase 1; Ryanodine Receptor Calcium Release Channel; Sarcoplasmic Reticulum
PubMed: 34822978
DOI: 10.1016/j.cellsig.2021.110203 -
MBio Oct 2023Pyrin, a unique cytosolic receptor, initiates inflammatory responses against RhoA-inactivating bacterial toxins and effectors like YopE and YopT. Understanding pyrin...
Pyrin, a unique cytosolic receptor, initiates inflammatory responses against RhoA-inactivating bacterial toxins and effectors like YopE and YopT. Understanding pyrin regulation is crucial due to its association with dysregulated inflammatory responses, including Familial Mediterranean Fever (FMF), linked to pyrin gene mutations. FMF mutations historically acted as a defense mechanism against plague. Negative regulation of pyrin through PKN phosphorylation is well established, with using the YopM effector to promote pyrin phosphorylation and counteract its activity. This study highlights the importance of phosphoprotein phosphatase activity in positively regulating pyrin inflammasome assembly in phagocytic cells of humans and mice. Oligomeric murine pyrin has S205 phosphorylated before inflammasome assembly, and this study implicates the dephosphorylation of murine pyrin S205 by two catalytic subunits of PP2A in macrophages. These findings offer insights for investigating the regulation of oligomeric pyrin and the balance of kinase and phosphatase activity in pyrin-associated infectious and autoinflammatory diseases.
Topics: Humans; Animals; Mice; Inflammasomes; Pyrin; Protein Processing, Post-Translational; Macrophages; Phosphoprotein Phosphatases; Mutation
PubMed: 37787552
DOI: 10.1128/mbio.02066-23 -
MBio Aug 2020Stimulator of interferon genes (STING) is an essential adaptor protein of the innate DNA-sensing signaling pathway, which recognizes genomic DNA from invading pathogens...
Stimulator of interferon genes (STING) is an essential adaptor protein of the innate DNA-sensing signaling pathway, which recognizes genomic DNA from invading pathogens to establish antiviral responses in host cells. STING activity is tightly regulated by several posttranslational modifications, including phosphorylation. However, specifically how the phosphorylation status of STING is modulated by kinases and phosphatases remains to be fully elucidated. In this study, we identified protein phosphatase 6 catalytic subunit (PPP6C) as a binding partner of Kaposi's sarcoma-associated herpesvirus (KSHV) open reading frame 48 (ORF48), which is a negative regulator of the cyclic GMP-AMP synthase (cGAS)-STING pathway. PPP6C depletion enhances double-stranded DNA (dsDNA)-induced and 5'ppp double-stranded RNA (dsRNA)-induced but not poly(I:C)-induced innate immune responses. PPP6C negatively regulates dsDNA-induced IRF3 activation but not NF-κB activation. Deficiency of PPP6C greatly inhibits the replication of herpes simplex virus 1 (HSV-1) and vesicular stomatitis virus (VSV) as well as the reactivation of KSHV, due to increased type I interferon production. We further demonstrated that PPP6C interacts with STING and that loss of PPP6C enhances STING phosphorylation. These data demonstrate the important role of PPP6C in regulating STING phosphorylation and activation, which provides an additional mechanism by which the host responds to viral infection. Cytosolic DNA, which usually comes from invading microbes, is a dangerous signal to the host. The cGAS-STING pathway is the major player that detects cytosolic DNA and then evokes the innate immune response. As an adaptor protein, STING plays a central role in controlling activation of the cGAS-STING pathway. Although transient activation of STING is essential to trigger the host defense during pathogen invasion, chronic STING activation has been shown to be associated with several autoinflammatory diseases. Here, we report that PPP6C negatively regulates the cGAS-STING pathway by removing STING phosphorylation, which is required for its activation. Dephosphorylation of STING by PPP6C helps prevent the sustained production of STING-dependent cytokines, which would otherwise lead to severe autoimmune disorders. This work provides additional mechanisms on the regulation of STING activity and might facilitate the development of novel therapeutics designed to prevent a variety of autoinflammatory disorders.
Topics: Animals; Chlorocebus aethiops; Gene Expression Regulation; HEK293 Cells; Herpesvirus 1, Human; Host-Pathogen Interactions; Humans; Immunity, Innate; Interferon Regulatory Factor-3; Membrane Proteins; Phosphoprotein Phosphatases; Phosphorylation; Vero Cells; Vesiculovirus; Virus Replication
PubMed: 32753499
DOI: 10.1128/mBio.01728-20 -
Journal of Cell Science Oct 2022Protein phosphorylation on serine and threonine residues is a widely distributed post-translational modification on proteins that acts to regulate their function.... (Review)
Review
Protein phosphorylation on serine and threonine residues is a widely distributed post-translational modification on proteins that acts to regulate their function. Phosphoprotein phosphatases (PPPs) contribute significantly to a plethora of cellular functions through the accurate dephosphorylation of phosphorylated residues. Most PPPs accomplish their purpose through the formation of complex holoenzymes composed of a catalytic subunit with various regulatory subunits. PPP holoenzymes then bind and dephosphorylate substrates in a highly specific manner. Despite the high prevalence of PPPs and their important role for cellular function, their mechanisms of action in the cell are still not well understood. Nevertheless, substantial experimental advancements in (phospho-)proteomics, structural and computational biology have contributed significantly to a better understanding of PPP biology in recent years. This Review focuses on recent approaches and provides an overview of substantial new insights into the complex mechanism of PPP holoenzyme regulation and substrate selectivity.
Topics: Holoenzymes; Phosphoprotein Phosphatases; Phosphoproteins; Phosphorylation; Protein Phosphatase 2; Serine; Threonine
PubMed: 36205606
DOI: 10.1242/jcs.259618