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Nature Communications Jan 2023The heptad repeats of the C-terminal domain (CTD) of RNA polymerase II (Pol II) are extensively modified throughout the transcription cycle. The CTD coordinates RNA...
The heptad repeats of the C-terminal domain (CTD) of RNA polymerase II (Pol II) are extensively modified throughout the transcription cycle. The CTD coordinates RNA synthesis and processing by recruiting transcription regulators as well as RNA capping, splicing and 3'end processing factors. The SPOC domain of PHF3 was recently identified as a CTD reader domain specifically binding to phosphorylated serine-2 residues in adjacent CTD repeats. Here, we establish the SPOC domains of the human proteins DIDO, SHARP (also known as SPEN) and RBM15 as phosphoserine binding modules that can act as CTD readers but also recognize other phosphorylated binding partners. We report the crystal structure of SHARP SPOC in complex with CTD and identify the molecular determinants for its specific binding to phosphorylated serine-5. PHF3 and DIDO SPOC domains preferentially interact with the Pol II elongation complex, while RBM15 and SHARP SPOC domains engage with writers and readers of mA, the most abundant RNA modification. RBM15 positively regulates mA levels and mRNA stability in a SPOC-dependent manner, while SHARP SPOC is essential for its localization to inactive X-chromosomes. Our findings suggest that the SPOC domain is a major interface between the transcription machinery and regulators of transcription and co-transcriptional processes.
Topics: Humans; Phosphorylation; Phosphoserine; RNA Polymerase II; RNA Processing, Post-Transcriptional; RNA Splicing; Transcription, Genetic; Protein Domains; DNA-Binding Proteins; RNA-Binding Proteins
PubMed: 36631525
DOI: 10.1038/s41467-023-35853-1 -
European Review For Medical and... Oct 2020To evaluate the neuroprotective role of phosphoserine (P-Ser) in primary open-angle glaucoma (POAG) patients and to compare its therapeutic effectiveness to placebo...
OBJECTIVE
To evaluate the neuroprotective role of phosphoserine (P-Ser) in primary open-angle glaucoma (POAG) patients and to compare its therapeutic effectiveness to placebo treatment.
PATIENTS AND METHODS
Fifty-one patients (24 males and 27 females) between 35 and 61 years (average 46 years ± 3.8 SD) affected by POAG were enrolled in this study. Patients were divided in two groups: group A included 28 subjects that received an oral P-Ser treatment for 12 months; and group B included 23 subjects that received an oral placebo treatment for 12 months. Complete ophthalmological examination, standard automated perimetric examination, analysis of ON fibers via scanning laser polarimetry and glaucoma staging was performed in all patients at enrolment and 1, 3, 6, and 12 months after. Statistical analysis was performed using STATA 14.0 (Collage Station, TX, USA).
RESULTS
Mean deviation (MD) and pattern standard deviation (PSD) analysis by means of 30-2 full threshold of the visual fields (VFs), retinal nerve fiber layer (RNFL) thickness by means of GDx, and IOP were considered to evaluate P-Ser therapy effectiveness in both groups. A statistically significant improvement (p<0.05) in VF, RNFL thickness and IOP compared to pre-treatment was found in patients in group A.
CONCLUSIONS
Our study shows a significant improvement in several variables in patients with glaucoma treated with P-Ser compared to placebo and suggests a potential neuroprotective effect of P-Ser in treating glaucoma patients in association with the traditional hypotonic topical therapy.
Topics: Administration, Oral; Adult; Female; Glaucoma, Open-Angle; Humans; Male; Middle Aged; Neuroprotective Agents; Phosphoserine
PubMed: 33090380
DOI: 10.26355/eurrev_202010_23186 -
Annual Review of Biophysics and... 2004Phosphoserine/threonine-binding domains integrate intracellular signal transduction events by forming multiprotein complexes with substrates of protein serine/threonine... (Review)
Review
Phosphoserine/threonine-binding domains integrate intracellular signal transduction events by forming multiprotein complexes with substrates of protein serine/threonine kinases. These phosphorylation-dependent molecular recognition events are responsible for coordinating the precise temporal and spatial response of cells to a wide range of stimuli, particularly those involved in cell cycle control and the response to DNA damage. The known families of phosphoserine/threonine-binding modules include 14-3-3 proteins, WW domains, FHA domains, WD40 repeats, and the Polo-box domains of Polo-like kinases. Peptide-library experiments reveal the optimal sequence motifs recognized by these domains, and facilitate high-resolution structural studies elucidating the mechanisms of phospho-dependent binding and the molecular basis for domain function within intricate signaling networks. Information emerging from these studies is critical for the design of novel experimental and therapeutic tools aimed at altering signal transduction cascades in normal and diseased cells.
Topics: Amino Acid Motifs; Binding Sites; Models, Molecular; Peptide Library; Phosphoserine; Protein Binding; Protein Interaction Mapping; Protein Structure, Tertiary; Threonine
PubMed: 15139812
DOI: 10.1146/annurev.biophys.33.110502.133346 -
Biomaterials Science Dec 2023Inflammatory M1 macrophages create a hostile environment that impedes wound healing. Phosphoserine (PS) is a naturally occurring immunosuppressive molecule capable of...
Inflammatory M1 macrophages create a hostile environment that impedes wound healing. Phosphoserine (PS) is a naturally occurring immunosuppressive molecule capable of polarizing macrophages from an inflammatory phenotype (M1) to an anti-inflammatory phenotype (M2). In this study, we designed, fabricated, and characterized PS-immobilized chitosan hydrogels as potential wound dressing materials. A PS group precursor was synthesized a phosphoramidite reaction and subsequently immobilized onto the chitosan chain through an EDC/-hydroxysuccinimide reaction using a crosslink moiety HPA. The PS/HPA-conjugated chitosan (CS-PS) was successfully synthesized by deprotecting the PS group in HCl. In addition, the hydrogels were prepared by the HRP/HO enzyme-catalyzed reaction with different PS group contents (0, 7.27, 44.28 and 56.88 μmol g). The immobilization of the PS group improved the hydrophilicity of the hydrogels. Interestingly, CS-PS hydrogel treatment upregulated both pro-inflammatory and anti-inflammatory cytokines. This treatment also resulted in alterations in the macrophage cell morphology from the M1 to M2 phenotype. The CS-PS hydrogel significantly accelerated diabetic wound healing. Overall, this study provides insights into the potential of PS-immobilized hydrogel materials for improved inflammatory disease therapy.
Topics: Chitosan; Hydrogels; Phosphoserine; Hydrogen Peroxide; Anti-Inflammatory Agents; Bandages; Apoptosis
PubMed: 37906511
DOI: 10.1039/d3bm01259j -
Talanta May 2017Cancer antigen 125 (CA 125) is widely used as diagnostic biomarker for ovarian cancer. Change in the concentration level of CA 125 is associated with disease progression...
Cancer antigen 125 (CA 125) is widely used as diagnostic biomarker for ovarian cancer. Change in the concentration level of CA 125 is associated with disease progression or regression. CA 125 posseses a phosphorylation site and protein backbone is phosphorylated on serine, before secretion. In this study, we have developed an imprinting method for CA 125 recognition and determination. In this method, methacryloyl antipyrine europium (III) [(MAAP)-Eu(III)] and methacryloyl antipyrine terbium (III) [(MAAP)-Tb(III)] have been used as new metal-chelating monomers via metal coordination-chelation interactions. Phosphoserine (PS) has been used as a template for the detection of CA 125. PS imprinted carbon nanotube (CNT) and FeO nanoparticle (SPN) have cavities that are selective for CA 125. The binding affinity of the PS imprinted CNT and SPN nanosensor has been investigated using Langmuir adsorption isotherms and affinity constants (K) have found to be 1.85 10M for PS and 13.5 10 mLU and 7.73 10 mLU for CA 125 (for CNT and SPN, respectively). Detection limit of PS imprinted CNT nanosensor for PS and CA 125 have been found to be 1.77 10M and 0.49 UmL, respectively. Human serum samples have been spiked with different concentrations of CA 125 (in pH 7.4 PBS) to investigate the feasibility of the nanosensors for clinical applications. Experimental results have been revealed that prepared nanosensors have been exhibited better sensivity, recovery and reproducibility.
Topics: CA-125 Antigen; Limit of Detection; Methacrylates; Molecular Imprinting; Nanotechnology; Nanotubes, Carbon; Phosphoserine
PubMed: 28340708
DOI: 10.1016/j.talanta.2017.01.093 -
Pesticide Biochemistry and Physiology May 2023Neonicotinoids are insect-selective nicotinic acetylcholine receptors (nAChRs) agonists that are used extensively for plant protection and animal health care. Some...
A consensus phosphoserine within the large cytoplasmic loop of insect nAChR α8 subunits modulated interaction between 14-3-3ε and nAChRs to regulate neonicotinoid efficacy.
Neonicotinoids are insect-selective nicotinic acetylcholine receptors (nAChRs) agonists that are used extensively for plant protection and animal health care. Some chaperone proteins, such as 14-3-3 proteins, importantly modulate nAChRs to display the physiological and pharmacological properties. Here we found that there is a 14-3-3 binding motif RSPSTH within the cytoplasmic loop of most insect α8 subunits. In the motif, a potential phosphorylated serine residue, serine 337, was a putative protein kinase A (PKA) substrate. Using Locusta migratoria α8 subunit as a representative, here we demonstrated that Loc14-3-3ε interacted with the unique phosphoserine (α8) of Locα8 subunit to regulate agonist efficacy on hybrid Locα8/β2 nAChRs in Xenopus oocytes. Co-expression of Loc14-3-3ε caused a dramatic rise of maximal inward currents (I) of Locα8/β2 for acetylcholine and imidacloprid to 2.9-fold and 3.1-fold of that of Locα8/β2 alone. The S337A substitution of Locα8 reduced the I rise when Locα8/β2 and Loc14-3-3ε were co-expressed. The increased agonist currents by exogenous Loc14-3-3ε on Locα8/β2 could be almost abolished by either PKA inhibitor KT5720 or 14-3-3 inhibitor difopein. The findings revealed that serine 337 within motif RSPSTH was important for the interaction between insect nAChRs and 14-3-3ε, and inhibiting the interaction would change the pharmacological property of insect nAChRs to agonist such as neonicotinoids which may provide insights to develop new targets for insecticide design.
Topics: Animals; Phosphoserine; Consensus; Insecta; Neonicotinoids; Receptors, Nicotinic; Oocytes; Xenopus laevis; Protein Subunits
PubMed: 37105614
DOI: 10.1016/j.pestbp.2023.105384 -
Acta Biomaterialia Mar 2020Calcium phosphate-based bone cements have been widely adopted in both orthopedic and dental applications. Phosphoserine (pSer), which has a natural role in...
Calcium phosphate-based bone cements have been widely adopted in both orthopedic and dental applications. Phosphoserine (pSer), which has a natural role in biomineralization, has been identified to possess the functionality to react with calcium phosphate phases, such as tetracalcium phosphate (TTCP) and α-tricalcium phosphate (α-TCP), and form a uniquely adhesive cement. This study investigated the chemical composition and phase evolution of a heterogeneous calcium phosphate (56% TTCP and 15% α-TCP) and pSer cement system with respect to pH. The coordination network of calcium phosphoserine monohydrate was discovered as the predominant crystalline phase of this adhesive apatitic cement system. Furthermore, it was determined that pH has a significant effect on the reaction kinetics of the system, whereby a lower pH tends to accelerate the reaction rate and favor products with lower Ca/P ratios. These findings provide a better understanding of the reaction and products of this adhesive organo-ceramic cement, which can be compositionally tuned for broad applications in the orthopedic and dental spaces. STATEMENT OF SIGNIFICANCE: The application of self-setting calcium phosphate cements (CPCs) in hard tissue regeneration has been a topic of significant research since their introduction to the field 30 years ago. Traditional CPCs, however, are limited by their suboptimal mechanical properties due to their solely inorganic composition. Recently, it was discovered that monomeric phosphoserine (pSer) is capable of serving as a setting reagent for a subset of CPC systems, resulting in an adhesive organo-ceramic composite. Despite its adhesive functionality and biomedical potential, its reaction chemistry and product composition were not well characterized. The present study identifies a calcium phosphoserine coordination network as the primary crystalline phase of this apatitic cement system and further characterizes compositional tunability of the products with respect to pH.
Topics: Apatites; Bone Cements; Calcium; Calcium Phosphates; Hydrogen-Ion Concentration; Models, Molecular; Phosphoserine; Resin Cements; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction
PubMed: 31945507
DOI: 10.1016/j.actbio.2020.01.007 -
Biochimica Et Biophysica Acta Jul 1956
Topics: Animals; Liver; Phosphoserine; Rabbits; Serine
PubMed: 13363884
DOI: 10.1016/0006-3002(56)90117-2 -
Toxicology in Vitro : An International... Jun 2023Epidemiological studies indicate that human and animal exposure to environmental mercury (Hg) disrupts normal immune system function, but the molecular mechanism...
At low levels, inorganic mercury interference with antigen signaling is associated with modifications to a panel of novel phosphoserine sites in B cell receptor pathway proteins.
Epidemiological studies indicate that human and animal exposure to environmental mercury (Hg) disrupts normal immune system function, but the molecular mechanism responsible for this is still unresolved. We have previously utilized phospho-proteomic mass spectrometry to demonstrate that in the absence of B Cell Receptor (BCR) stimulation, exposure of B cells to Hg induces significant changes to a great many elements of the BCR signaling pathway in a concentration dependent manner. In this report, we have extended those initial findings by utilizing mass spectrometry to evaluate in detail the effect of low-level Hg exposure on BCR induced phospho-proteomic changes. Specifically, murine WEHI-231 B lymphoma cells were exposed to environmentally relevant levels of Hg with or without concomitant BCR stimulation. The cellular phospho-proteomes were then profiled by LC-MS/MS. We found that for low-level exposures, Hg interference with signal transduction across the BCR pathway was predominantly associated with modification of phosphorylation of 12 phosphosites located on seven different proteins. Nine sites were serine, two sites tyrosine and one site threonine. Most of these sites are novel, in the sense that only the two tyrosine and one of the serine sites have previously been reported to be associated with BCR signaling.
Topics: Animals; Mice; Humans; Phosphoserine; Mercury; Chromatography, Liquid; Proteomics; Cell Line; Tandem Mass Spectrometry; Signal Transduction; Receptors, Antigen, B-Cell; Proteins; Phosphorylation; Tyrosine
PubMed: 36736710
DOI: 10.1016/j.tiv.2023.105564 -
Autophagy Sep 2020There is a type of noncanonical autophagy, which is independent of ATG5 (autophagy related 5), also referred to as alternative autophagy. Both canonical and...
There is a type of noncanonical autophagy, which is independent of ATG5 (autophagy related 5), also referred to as alternative autophagy. Both canonical and ATG5-independent alternative autophagy require the initiator ULK1 (unc-51 like kinase 1), but how ULK1 regulates these two types of autophagy differently remains unclear. A recent paper from Torii et al. demonstrates that phosphorylation of ULK1 at Ser746 by RIPK3 (receptor interacting serine/threonine kinase 3) is the key difference between these two types of autophagy; this phosphorylation is exclusively found during alternative autophagy.
Topics: Animals; Autophagy; Autophagy-Related Protein 5; Autophagy-Related Protein-1 Homolog; Fibroblasts; Mice; Phosphorylation; Phosphoserine
PubMed: 32544365
DOI: 10.1080/15548627.2020.1780844