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Biochemical and Biophysical Research... Oct 2023Myosin phosphatase (MP) is an enzyme complex that regulates muscle contraction and plays important roles in various physiological and pathological conditions. Myosin...
Myosin phosphatase (MP) is an enzyme complex that regulates muscle contraction and plays important roles in various physiological and pathological conditions. Myosin phosphatase targeting subunit (MYPT) 2, a subunit of MP, interacts with protein phosphatase 1c to regulate its phosphatase activity. MYPT2 exists in various isoforms that differ in the composition of essential motifs that contribute to its function. However, regulatory mechanisms underlying these isoforms are poorly understood. Human leukocyte antigen-F adjacent transcript 10 (FAT10) is a ubiquitin-like modifier that not only targets proteins for proteasomal degradation but also stabilizes its interacting proteins. In this study, we investigated the effect of the interaction between FAT10 and MYPT2 isoform a (the canonical full-length form of MYPT2) or MYPT2 isoform f (the natural truncated form of MYPT2). FAT10 interacted with both MYPT2 isoforms a and f; however, only MYPT2 isoform f was increased by FAT10, whereas MYPT2 isoform a remained unaffected by FAT10. We further confirmed that, in contrast to MYPT2 isoform a, MYPT2 isoform f undergoes rapid degradation via the ubiquitin-proteasome pathway and that FAT10 stabilizes MYPT2 isoform f by inhibiting its ubiquitination. Therefore, our findings suggest that the interaction between FAT10 and MYPT2 isoforms leads to distinct stabilization effects on each isoform, potentially modulating MP activity.
Topics: Humans; Myosin-Light-Chain Phosphatase; Protein Isoforms; Protein Phosphatase 1; Ubiquitin; Ubiquitination; Ubiquitins
PubMed: 37506472
DOI: 10.1016/j.bbrc.2023.07.025 -
EMBO Reports Dec 2023Planar cell polarity (PCP) signaling polarizes epithelial cells within the plane of an epithelium. Core PCP signaling components adopt asymmetric subcellular...
Planar cell polarity (PCP) signaling polarizes epithelial cells within the plane of an epithelium. Core PCP signaling components adopt asymmetric subcellular localizations within cells to both polarize and coordinate polarity between cells. Achieving subcellular asymmetry requires additional effectors, including some mediating post-translational modifications of core components. Identification of such proteins is challenging due to pleiotropy. We used mass spectrometry-based proximity labeling proteomics to identify such regulators in the Drosophila wing. We identified the catalytic subunit of protein phosphatase1, Pp1-87B, and show that it regulates core protein polarization. Pp1-87B interacts with the core protein Van Gogh and at least one serine/threonine kinase, Dco/CKIε, that is known to regulate PCP. Pp1-87B modulates Van Gogh subcellular localization and directs its dephosphorylation in vivo. PNUTS, a Pp1 regulatory subunit, also modulates PCP. While the direct substrate(s) of Pp1-87B in control of PCP is not known, our data support the model that cycling between phosphorylated and unphosphorylated forms of one or more core PCP components may regulate acquisition of asymmetry. Finally, our screen serves as a resource for identifying additional regulators of PCP signaling.
Topics: Animals; Cell Polarity; Drosophila Proteins; Membrane Proteins; Protein Phosphatase 1; Protein Processing, Post-Translational; Protein Serine-Threonine Kinases; Signal Transduction
PubMed: 37975164
DOI: 10.15252/embr.202356997 -
European Journal of Medicinal Chemistry Jan 2024Phosphatase is a kind of enzyme that can dephosphorylate target proteins, which can be divided into serine/threonine phosphatase and tyrosine phosphatase according to... (Review)
Review
Phosphatase is a kind of enzyme that can dephosphorylate target proteins, which can be divided into serine/threonine phosphatase and tyrosine phosphatase according to its mode of action. Current evidence showed multiple phosphatases were highly correlated with diseases including various cancers, demonstrating them as potential targets. However, currently, targeting phosphatases with small molecules faces many challenges, resulting in no drug approved. In this case, phosphatases are even regarded as "undruggable" targets for a long time. Recently, a variety of strategies have been adopted in the design of small molecule inhibitors targeting phosphatases, leading many of them to enter into the clinical trials. In this review, we classified these inhibitors into 4 types, including (1) molecular glues, (2) small molecules targeting catalytic sites, (3) allosteric inhibition, and (4) bifunctional molecules (proteolysis targeting chimeras, PROTACs). These molecules with diverse strategies prove the feasibility of phosphatases as drug targets. In addition, the combination therapy of phosphatase inhibitors with other drugs has also entered clinical trials, which suggests a broad prospect. Thus, targeting phosphatases with small molecules by different strategies is emerging as a promising way in the modulation of pathogenetic phosphorylation.
Topics: Humans; Phosphoprotein Phosphatases; Protein Tyrosine Phosphatases; Enzyme Inhibitors; Phosphorylation; Neoplasms; Proteolysis
PubMed: 38101039
DOI: 10.1016/j.ejmech.2023.116031 -
JCI Insight Jul 2023Chemotherapy-related cognitive impairment (CRCI) or "chemo brain" is a devastating neurotoxic sequela of cancer-related treatments, especially for the elderly...
Chemotherapy-related cognitive impairment (CRCI) or "chemo brain" is a devastating neurotoxic sequela of cancer-related treatments, especially for the elderly individuals. Here we show that PTPRO, a tyrosine phosphatase, is highly enriched in the hippocampus, and its level is tightly associated with neurocognitive function but declined significantly during aging. To understand the protective role of PTPRO in CRCI, a mouse model was generated by treating Ptpro-/- female mice with doxorubicin (DOX) because Ptpro-/- female mice are more vulnerable to DOX, showing cognitive impairments and neurodegeneration. By analyzing PTPRO substrates that are neurocognition-associated tyrosine kinases, we found that SRC and EPHA4 are highly phosphorylated/activated in the hippocampi of Ptpro-/- female mice, with increased sensitivity to DOX-induced CRCI. On the other hand, restoration of PTPRO in the hippocampal CA3 region significantly ameliorate CRCI in Ptpro-/- female mice. In addition, we found that the plant alkaloid berberine (BBR) is capable of ameliorating CRCI in aged female mice by upregulating hippocampal PTPRO. Mechanistically, BBR upregulates PTPRO by downregulating miR-25-3p, which directly targeted PTPRO. These findings collectively demonstrate the protective role of hippocampal PTPRO against CRCI.
Topics: Animals; Mice; Chemotherapy-Related Cognitive Impairment; Hippocampus; Protein Tyrosine Phosphatases; Protein-Tyrosine Kinases; Tyrosine
PubMed: 37485875
DOI: 10.1172/jci.insight.166306 -
The EMBO Journal Jul 2023The AAA+-ATPase p97 (also called VCP or Cdc48) unfolds proteins and disassembles protein complexes in numerous cellular processes, but how substrate complexes are loaded...
The AAA+-ATPase p97 (also called VCP or Cdc48) unfolds proteins and disassembles protein complexes in numerous cellular processes, but how substrate complexes are loaded onto p97 and disassembled is unclear. Here, we present cryo-EM structures of p97 in the process of disassembling a protein phosphatase-1 (PP1) complex by extracting an inhibitory subunit from PP1. We show that PP1 and its partners SDS22 and inhibitor-3 (I3) are loaded tightly onto p97, surprisingly via a direct contact of SDS22 with the p97 N-domain. Loading is assisted by the p37 adapter that bridges two adjacent p97 N-domains underneath the substrate complex. A stretch of I3 is threaded into the central channel of the spiral-shaped p97 hexamer, while other elements of I3 are still attached to PP1. Thus, our data show how p97 arranges a protein complex between the p97 N-domain and central channel, suggesting a hold-and-extract mechanism for p97-mediated disassembly.
Topics: Ubiquitin; Protein Phosphatase 1; ATPases Associated with Diverse Cellular Activities; Models, Molecular; Valosin Containing Protein; Cell Cycle Proteins
PubMed: 37264685
DOI: 10.15252/embj.2022113110 -
Nature Communications Aug 2023Loss of the tumor suppressive activity of the protein phosphatase 2A (PP2A) is associated with cancer, but the underlying molecular mechanisms are unclear. PP2A...
Loss of the tumor suppressive activity of the protein phosphatase 2A (PP2A) is associated with cancer, but the underlying molecular mechanisms are unclear. PP2A holoenzyme comprises a heterodimeric core, a scaffolding A subunit and a catalytic C subunit, and one of over 20 distinct substrate-directing regulatory B subunits. Methylation of the C subunit regulates PP2A heterotrimerization, affecting B subunit binding and substrate specificity. Here, we report that the leucine carboxy methyltransferase (LCMT1), which methylates the L309 residue of the C subunit, acts as a suppressor of androgen receptor (AR) addicted prostate cancer (PCa). Decreased methyl-PP2A-C levels in prostate tumors is associated with biochemical recurrence and metastasis. Silencing LCMT1 increases AR activity and promotes castration-resistant prostate cancer growth. LCMT1-dependent methyl-sensitive AB56αCme heterotrimers target AR and its critical coactivator MED1 for dephosphorylation, resulting in the eviction of the AR-MED1 complex from chromatin and loss of target gene expression. Mechanistically, LCMT1 is regulated by S6K1-mediated phosphorylation-induced degradation requiring the β-TRCP, leading to acquired resistance to anti-androgens. Finally, feedforward stabilization of LCMT1 by small molecule activator of phosphatase (SMAP) results in attenuation of AR-signaling and tumor growth inhibition in anti-androgen refractory PCa. These findings highlight methyl-PP2A-C as a prognostic marker and that the loss of LCMT1 is a major determinant in AR-addicted PCa, suggesting therapeutic potential for AR degraders or PP2A modulators in prostate cancer treatment.
Topics: Humans; Male; Androgen Antagonists; Leucine; Methyltransferases; Prostate; Prostatic Neoplasms; Protein Phosphatase 2
PubMed: 37644036
DOI: 10.1038/s41467-023-40760-6 -
Cellular and Molecular Life Sciences :... Jul 2023Dual specificity phosphatase 1 (DUSP1) and valosin-containing protein (VCP) have both been reported to regulate mitochondrial homeostasis. However, their impact on...
Dual specificity phosphatase 1 (DUSP1) and valosin-containing protein (VCP) have both been reported to regulate mitochondrial homeostasis. However, their impact on mitochondrial quality control (MQC) and myocardial function during LPS-induced endotoxemia remains unclear. We addressed this issue by modeling LPS-induced endotoxemia in DUSP1 transgenic (DUSP1) mice and in cultured DUSP1-overexpressing HL-1 cardiomyocytes. Accompanying characteristic structural and functional deficits, cardiac DUSP1 expression was significantly downregulated following endotoxemia induction in wild type mice. In contrast, markedly reduced myocardial inflammation, cardiomyocyte apoptosis, cardiac structural disorder, cardiac injury marker levels, and normalized systolic/diastolic function were observed in DUSP1 mice. Furthermore, DUSP1 overexpression in HL-1 cells significantly attenuated LPS-mediated mitochondrial dysfunction by preserving MQC, as indicated by normalized mitochondrial dynamics, improved mitophagy, enhanced biogenesis, and attenuated mitochondrial unfolded protein response. Molecular assays showed that VCP was a substrate of DUSP1 and the interaction between DUSP1 and VCP primarily occurred on the mitochondria. Mechanistically, DUSP1 phosphatase domain promoted the physiological DUSP1/VCP interaction which prevented LPS-mediated VCP Ser784 phosphorylation. Accordingly, transfection with a phosphomimetic VCP mutant abolished the protective actions of DUSP1 on MQC and aggravated inflammation, apoptosis, and contractility/relaxation capacity in HL-1 cardiomyocytes. These findings support the involvement of the novel DUSP1/VCP/MQC pathway in the pathogenesis of endotoxemia-caused myocardial dysfunction.
Topics: Animals; Mice; Cardiomyopathies; Dual Specificity Phosphatase 1; Endotoxemia; Lipopolysaccharides; Mitochondria; Myocytes, Cardiac; Valosin Containing Protein
PubMed: 37464072
DOI: 10.1007/s00018-023-04863-z -
Renal Failure Dec 2023Hemodialysis (HD) patients are at risk for sarcopenia (SP) and bone loss, which may impact falls and bone fragility and lead to poor prognosis. Patients with HD and...
BACKGROUND
Hemodialysis (HD) patients are at risk for sarcopenia (SP) and bone loss, which may impact falls and bone fragility and lead to poor prognosis. Patients with HD and those with osteoporosis (OP) are still underdiagnosed and untreated. The aims of the present study were to evaluate the factors that affect bone mineral density (BMD) loss in HD patients, and explore traditional and novel approaches to manage chronic kidney disease-mineral-bone disorder (CKD-MBD).
METHODS
Patients who underwent regular HD at the First Affiliated Hospital of Soochow University were retrospectively evaluated. According to the WHO osteoporosis criteria, patients were categorized into three groups: normal BMD, osteopenia, and osteoporosis. Demographic and clinical data, skeletal muscle mass, and bone turnover markers(BTM) were compared between the three groups. The correlation between bone density and muscle mass was calculated, and related risk factors were analyzed.
RESULTS
This study enrolled 130 HD patients, 36 patients were diagnosed with sarcopenia (27.7%), 44 patients were diagnosed with osteopenia (33.8%), 19 patients were diagnosed with osteoporosis (14.6%), and 23 patients were diagnosed with osteosarcopenia (17.7%). The SMI was positively correlated with the BMD of the lumbar spine ( = 0.23, < 0.01) and femoral neck ( = 0.22, < 0.05). In ordinal logistic regression analysis, the odds ratio (OR) for low BMD was high for patients with sarcopenia (OR = 5.894, 95% CI 1.592-21.830, < 0.01), older age (OR = 1.095, 95% CI 1.041-1.153, < 0.001), higher TRACP-5b levels (OR = 1.597, 95% CI 1.230-2.072, < 0.01), and lower 25-OH vitamin D levels (OR = 0.631, 95% CI 0.544-0.733, < 0.001).
CONCLUSION
The preservation of skeletal muscle mass could be important to prevent a BMD decrease in HD patients. Adequate intake of vitamin D and control of TRACP-5b levels will help reduce the occurrence and progression of osteopenia/sarcopenia in HD patients.
Topics: Humans; Bone Density; Bone Diseases, Metabolic; Bone Remodeling; Osteoporosis; Renal Dialysis; Retrospective Studies; Sarcopenia; Tartrate-Resistant Acid Phosphatase; Vitamin D; Chronic Kidney Disease-Mineral and Bone Disorder
PubMed: 37122165
DOI: 10.1080/0886022X.2023.2200846 -
The EMBO Journal Aug 2023CDC14, originally identified as crucial mediator of mitotic exit in budding yeast, belongs to the family of dual-specificity phosphatases (DUSPs) that are present in... (Review)
Review
CDC14, originally identified as crucial mediator of mitotic exit in budding yeast, belongs to the family of dual-specificity phosphatases (DUSPs) that are present in most eukaryotes. Contradicting data have sparked a contentious discussion whether a cell cycle role is conserved in the human paralogs CDC14A and CDC14B but possibly masked due to redundancy. Subsequent studies on CDC14A and CDC14B double knockouts in human and mouse demonstrated that CDC14 activity is dispensable for mitotic progression in higher eukaryotes and instead suggested functional specialization. In this review, we provide a comprehensive overview of our current understanding of how faithful cell division is linked to phosphorylation and dephosphorylation and compare functional similarities and divergences between the mitotic phosphatases CDC14, PP2A, and PP1 from yeast and higher eukaryotes. Furthermore, we review the latest discoveries on CDC14B, which identify this nuclear phosphatase as a key regulator of gene expression and reveal its role in neuronal development. Finally, we discuss CDC14B functions in meiosis and possible implications in other developmental processes.
Topics: Humans; Animals; Mice; Saccharomyces cerevisiae; Protein Tyrosine Phosphatases; Cell Division; Cell Cycle; Dual-Specificity Phosphatases; Cell Cycle Proteins; Phosphorylation; Mitosis; Saccharomyces cerevisiae Proteins
PubMed: 37493185
DOI: 10.15252/embj.2023114364 -
Aging Nov 2023
Topics: Protein Phosphatase 2; Cell Death; Regulated Cell Death
PubMed: 37950723
DOI: 10.18632/aging.205303