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Kommer DC, Stamatiou K, Vagnarelli P. Cell Cycle-Specific Protein Phosphatase 1 (PP1) Substrates Identification Using Genetically Modified Cell Lines. Methods Mol Biol 2024; 2740:37-61. [PMID: 38393468 DOI: 10.1007/978-1-0716-3557-5_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
The identification of protein phosphatase 1 (PP1) holoenzyme substrates has proven to be a challenging task. PP1 can form different holoenzyme complexes with a variety of regulatory subunits, and many of those are cell cycle regulated. Although several methods have been used to identify PP1 substrates, their cell cycle specificity is still an unmet need. Here, we present a new strategy to investigate PP1 substrates throughout the cell cycle using clustered regularly interspersed short palindromic repeats (CRISPR)-Cas9 genome editing and generate cell lines with endogenously tagged PP1 regulatory subunit (regulatory interactor of protein phosphatase one, RIPPO). RIPPOs are tagged with the auxin-inducible degron (AID) or ascorbate peroxidase 2 (APEX2) modules, and PP1 substrate identification is conducted by SILAC proteomic-based approaches. Proteins in close proximity to RIPPOs are first identified through mass spectrometry (MS) analyses using the APEX2 system; then a list of differentially phosphorylated proteins upon RIPPOs rapid degradation (achieved via the AID system) is compiled via SILAC phospho-mass spectrometry. The "in silico" overlap between the two proteomes will be enriched for PP1 putative substrates. Several methods including fluorescence resonance energy transfer (FRET), proximity ligation assays (PLA), and in vitro assays can be used as substrate validations approaches.
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Affiliation(s)
- Dorothee C Kommer
- College of Health, Medicine and Life Science, Brunel University London, London, UK
| | | | - Paola Vagnarelli
- College of Health, Medicine and Life Science, Brunel University London, London, UK.
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Christensen KR, Combs B, Richards C, Grabinski T, Alhadidy MM, Kanaan NM. Phosphomimetics at Ser199/Ser202/Thr205 in Tau Impairs Axonal Transport in Rat Hippocampal Neurons. Mol Neurobiol 2023; 60:3423-3438. [PMID: 36859689 PMCID: PMC10122714 DOI: 10.1007/s12035-023-03281-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/16/2023] [Indexed: 03/03/2023]
Abstract
Our understanding of the biological functions of the tau protein now includes its role as a scaffolding protein involved in signaling regulation, which also has implications for tau-mediated dysfunction and degeneration in Alzheimer's disease and other tauopathies. Recently, we found that pseudophosphorylation at sites linked to the pathology-associated AT8 phosphoepitope of tau disrupts normal fast axonal transport through a protein phosphatase 1 (PP1)-dependent pathway in squid axoplasm. Activation of the pathway and the resulting transport deficits required tau's N-terminal phosphatase-activating domain (PAD) and PP1 but the connection between tau and PP1 was not well defined. Here, we studied functional interactions between tau and PP1 isoforms and their effects on axonal transport in mammalian neurons. First, we found that wild-type tau interacted with PP1α and PP1γ primarily through its microtubule-binding repeat domain. Pseudophosphorylation of tau at S199/S202/T205 (psTau) increased PAD exposure, enhanced interactions with PP1γ, and increased active PP1γ levels in mammalian cells. Expression of psTau also significantly impaired axonal transport in primary rat hippocampal neurons. Deletion of PAD in psTau significantly reduced the interaction with PP1γ, eliminated increases of active PP1γ levels, and rescued axonal transport impairment in neurons. These data suggest that a functional consequence of phosphorylation within S199-T205 in tau, which occurs in AD and several other tauopathies, may be aberrant interaction with and activation of PP1γ and subsequent axonal transport disruption in a PAD-dependent fashion.
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Affiliation(s)
- Kyle R Christensen
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Benjamin Combs
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Collin Richards
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Tessa Grabinski
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Mohammed M Alhadidy
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Nicholas M Kanaan
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA.
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA.
- Hauenstein Neuroscience Center, Mercy Health Saint Mary's, Grand Rapids, MI, 49503, USA.
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Lester WC, Johnson T, Hale B, Serra N, Elgart B, Wang R, Geyer CB, Sperry AO. Aurora a kinase (AURKA) is required for male germline maintenance and regulates sperm motility in the mouse. Biol Reprod 2021; 105:1603-1616. [PMID: 34518881 DOI: 10.1093/biolre/ioab168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 03/12/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
Aurora A kinase (AURKA) is an important regulator of cell division and is required for assembly of the mitotic spindle. We recently reported the unusual finding that this mitotic kinase is also found on the sperm flagellum. To determine its requirement in spermatogenesis, we generated conditional knockout animals with deletion of the Aurka gene in either spermatogonia or spermatocytes to assess its role in mitotic and postmitotic cells, respectively. Deletion of Aurka in spermatogonia resulted in disappearance of all developing germ cells in the testis, as expected given its vital role in mitotic cell division. Deletion of Aurka in spermatocytes reduced testis size, sperm count, and fertility, indicating disruption of meiosis or an effect on spermiogenesis in developing mice. Interestingly, deletion of Aurka in spermatocytes increased apoptosis in spermatocytes along with an increase in the percentage of sperm with abnormal morphology. Despite the increase in abnormal sperm, sperm from spermatocyte Aurka knockout mice displayed increased progressive motility. In addition, sperm lysate prepared from Aurka knockout animals had decreased protein phosphatase 1 (PP1) activity. Together, our results show that AURKA plays multiple roles in spermatogenesis, from mitotic divisions of spermatogonia to sperm morphology and motility.
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Affiliation(s)
- William C Lester
- Department of Anatomy and Cell Biology at the Brody School of Medicine
| | - Taylor Johnson
- Department of Anatomy and Cell Biology at the Brody School of Medicine.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville NC, USA 27834
| | - Ben Hale
- Department of Anatomy and Cell Biology at the Brody School of Medicine.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville NC, USA 27834
| | - Nicholas Serra
- Department of Anatomy and Cell Biology at the Brody School of Medicine.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville NC, USA 27834
| | - Brian Elgart
- Department of Anatomy and Cell Biology at the Brody School of Medicine
| | - Rong Wang
- Department of Anatomy and Cell Biology at the Brody School of Medicine
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology at the Brody School of Medicine.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville NC, USA 27834
| | - Ann O Sperry
- Department of Anatomy and Cell Biology at the Brody School of Medicine
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Bresch AM, Yerich N, Wang R, Sperry AO. The PP1 regulator PPP1R2 coordinately regulates AURKA and PP1 to control centrosome phosphorylation and maintain central spindle architecture. BMC Mol Cell Biol 2020; 21:84. [PMID: 33238888 PMCID: PMC7687763 DOI: 10.1186/s12860-020-00327-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 11/04/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Maintenance of centrosome number in cells is essential for accurate distribution of chromosomes at mitosis and is dependent on both proper centrosome duplication during interphase and their accurate distribution to daughter cells at cytokinesis. Two essential regulators of cell cycle progression are protein phosphatase 1 (PP1) and Aurora A kinase (AURKA), and their activities are each regulated by the PP1 regulatory subunit, protein phosphatase 1 regulatory subunit 2 (PPP1R2). We observed an increase in centrosome number after overexpression of these proteins in cells. Each of these proteins is found on the midbody in telophase and overexpression of PPP1R2 and its mutants increased cell ploidy and disrupted cytokinesis. This suggests that the increase in centrosome number we observed in PPP1R2 overexpressing cells was a consequence of errors in cell division. Furthermore, overexpression of PPP1R2 and its mutants increased midbody length and disrupted midbody architecture. Additionally, we show that overexpression of PPP1R2 alters activity of AURKA and PP1 and their phosphorylation state at the centrosome. RESULTS Overexpression of PPP1R2 caused an increase in the frequency of supernumerary centrosomes in cells corresponding to aberrant cytokinesis reflected by increased nuclear content and cellular ploidy. Furthermore, AURKA, PP1, phospho PPP1R2, and PPP1R2 were all localized to the midbody at telophase, and PP1 localization there was dependent on binding of PPP1R2 with PP1 and AURKA as well as its phosphorylation state. Additionally, overexpression of both PPP1R2 and its C-terminal AURKA binding site altered enzymatic activity of AURKA and PP1 at the centrosome and disrupted central spindle structure. CONCLUSIONS Results from our study reveal the involvement of PPP1R2 in coordinating PP1 and AURKA activity during cytokinesis. Overexpression of PPP1R2 or its mutants disrupted the midbody at cytokinesis causing accumulation of centrosomes in cells. PPP1R2 recruited PP1 to the midbody and interference with its targeting resulted in elongated and severely disrupted central spindles supporting an important role for PPP1R2 in cytokinesis.
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Affiliation(s)
- Alan-Michael Bresch
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA
| | - Nadiya Yerich
- University of North Carolina School of Medicine, Chapel Hill, NC, 27599, USA
| | - Rong Wang
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA
| | - Ann O Sperry
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC, 27834, USA.
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Liu Y, Zhou D, Feng J, Liu Z, Hu Y, Liu C, Kong X. HIV-1 Protein Tat 1-72 Impairs Neuronal Dendrites via Activation of PP1 and Regulation of the CREB/BDNF Pathway. Virol Sin 2018; 33:261-9. [PMID: 29737506 DOI: 10.1007/s12250-018-0031-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/02/2018] [Indexed: 12/18/2022] Open
Abstract
Despite the success of combined antiretroviral therapy in recent years, the prevalence of human immunodeficiency virus (HIV)-associated neurocognitive disorders in people living with HIV-1 is increasing, significantly reducing the health-related quality of their lives. Although neurons cannot be infected by HIV-1, shed viral proteins such as transactivator of transcription (Tat) can cause dendritic damage. However, the detailed molecular mechanism of Tat-induced neuronal impairment remains unknown. In this study, we first showed that recombinant Tat (1-72 aa) induced neurotoxicity in primary cultured mouse neurons. Second, exposure to Tat1-72 was shown to reduce the length and number of dendrites in cultured neurons. Third, Tat1-72 (0-6 h) modulates protein phosphatase 1 (PP1) expression and enhances its activity by decreasing the phosphorylation level of PP1 at Thr320. Finally, Tat1-72 (24 h) downregulates CREB activity and CREB-mediated gene (BDNF, c-fos, Egr-1) expression. Together, these findings suggest that Tat1-72 might impair cognitive function by regulating the activity of PP1 and the CREB/BDNF pathway.
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Zhang X, Ma D, Caruso M, Lewis M, Qi Y, Yi Z. Quantitative phosphoproteomics reveals novel phosphorylation events in insulin signaling regulated by protein phosphatase 1 regulatory subunit 12A. J Proteomics 2014; 109:63-75. [PMID: 24972320 DOI: 10.1016/j.jprot.2014.06.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 06/11/2014] [Accepted: 06/14/2014] [Indexed: 01/07/2023]
Abstract
UNLABELLED Serine/threonine protein phosphatase 1 regulatory subunit 12A (PPP1R12A) modulates the activity and specificity of the catalytic subunit of protein phosphatase 1, regulating various cellular processes via dephosphorylation. Nonetheless, little is known about phosphorylation events controlled by PPP1R12A in skeletal muscle insulin signaling. Here, we used quantitative phosphoproteomics to generate a global picture of phosphorylation events regulated by PPP1R12A in a L6 skeletal muscle cell line, which were engineered for inducible PPP1R12A knockdown. Phosphoproteomics revealed 3876 phosphorylation sites (620 were novel) in these cells. Furthermore, PPP1R12A knockdown resulted in increased overall phosphorylation in L6 cells at the basal condition, and changed phosphorylation levels for 698 sites (assigned to 295 phosphoproteins) at the basal and/or insulin-stimulated conditions. Pathway analysis on the 295 phosphoproteins revealed multiple significantly enriched pathways related to insulin signaling, such as mTOR signaling and RhoA signaling. Moreover, phosphorylation levels for numerous regulatory sites in these pathways were significantly changed due to PPP1R12A knockdown. These results indicate that PPP1R12A indeed plays a role in skeletal muscle insulin signaling, providing novel insights into the biology of insulin action. This new information may facilitate the design of experiments to better understand mechanisms underlying skeletal muscle insulin resistance and type 2 diabetes. BIOLOGICAL SIGNIFICANCE These results identify a large number of potential new substrates of serine/threonine protein phosphatase 1 and suggest that serine/threonine protein phosphatase 1 regulatory subunit 12A indeed plays a regulatory role in multiple pathways related to insulin action, providing novel insights into the biology of skeletal muscle insulin signaling. This information may facilitate the design of experiments to better understand the molecular mechanism responsible for skeletal muscle insulin resistance and associated diseases, such as type 2 diabetes and cardiovascular diseases.
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Affiliation(s)
- Xiangmin Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Danjun Ma
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Michael Caruso
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Monique Lewis
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Yue Qi
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Zhengping Yi
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48202, USA.
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