Search Results (78)

Dengue virus (DENV) is a mosquito-borne RNA virus that causes serious illness in humans, ranging from mild fever to severe clinical manifestations, with dengue virus type 2 (DENV-2) being the most virulent among its four serotypes. Despite extensive research, no specific antiviral therapy is currently available, making the host-directed method an appealing therapeutic approach. Evidence shows that DENV manipulates host kinase-driven phosphorylation pathways to control viral pathogenesis. Using the kinase–substrate phosphomotif approach, we predicted phosphorylation sites across the DENV proteome and their potential human kinases. The predicted kinase–substrate interactions were systematically integrated with DENV-2-induced human phosphoproteome datasets, protein–protein interactions, and experimentally-validated viral phosphosites. The therapeutic relevance of the identified host kinases was corroborated by the impact of their inhibitors on DENV-2 infection. Among the 359 potential human kinases predicted to phosphorylate DENV-2 proteins, based on human phosphoproteome and kinase–viral protein interaction analyses, CDK9 emerged as a central hub kinase. Molecular docking analyses further revealed that the host kinases CDK9, EEF2K, HASPIN, and TNNI3K form stable interactions with the viral capsid and NS5 proteins. Additionally, a conservation analysis suggested that the predicted phosphorylation sites are evolutionarily conserved across DENV-2 strains. Computational prediction tools supported the predicted kinase–substrate interactions, underscoring the role of host kinases as key regulators of DENV infection, which may act as potential therapeutic targets. This study highlights the interplay between dengue viral and host proteins, providing insights into host-directed therapeutic strategies for DENV-2 infection and their potential to address the current lack of effective antiviral interventions. Full article

High-density lipoprotein-binding protein (HDLBP), also called Vigilin, is a multifunctional RNA-binding protein with established roles in RNA transport and regulation, chromosome segregation, lipid homeostasis, and translational regulation. Frequently detected to be perturbed in phosphoproteome analysis, phosphorylation is indicated as a major mechanism in the regulation of HDLBP functions; however, its phosphorylation landscape remains unexplored. We performed a meta-phosphoproteome analysis of HDLBP to map site-specific functional and regulatory roles of its two most frequently detected phosphosites, S31 and S944. Co-occurrence analysis across multiple datasets indicated that they can be phosphorylated together, suggesting potential co-ordinated regulation. Site-specific co-regulation analysis revealed distinct phospho-regulatory networks, with upstream kinases identified exclusively for S944. Functional enrichment of co-regulated protein phosphosites (CPPs) highlighted its role in RNA metabolism, chromosome organization, and nucleoplasmic transport, while functional annotation of site-specific phosphorylation of CPPs indicates its involvement in cell cycle regulation, apoptosis, and carcinogenesis. Additionally, the potential role of CPPs in the lipid homeostasis network was explored. Furthermore, the differential expression of HDLBP phosphosites across multiple cancers was observed using UALCAN, suggesting a potential role for phospho-regulation of HDLBP in tumor-associated pathways. Together, these findings provide the first integrated view of HDLBP phosphorylation and could serve as a valuable framework for future targeted studies to elucidate the mechanistic roles of site-specific HDLBP phosphorylation in cellular and pathophysiological processes. Full article

Protein Kinase N1 (PKN1) is a PKC-related serine/threonine kinase of the AGC group within the eukaryotic protein kinase superfamily (ePK) that orchestrates oncogenic, metabolic, and cytoskeletal signaling. Despite these critical roles, the phosphorylation-dependent regulatory network of PKN1 remains largely undefined. We performed a large-scale phosphoproteomic data integration of publicly available human datasets (892 profiling datasets and 191 differential datasets) to identify recurrent PKN1 phosphorylation sites. This analysis identified two predominant PKN1 phosphosites, S562 and S916, that were frequently observed and differentially regulated across studies. The S916 maps to a turn motif (TM) in the AGC group of kinases, which is evolutionarily conserved among PKN paralogs, while S562 is non-conserved and appears to be PKN1-specific. Co-regulation and enrichment analyses suggest that S916 is associated with insulin/AMPK signaling and metabolic pathways, whereas S562 co-occurs with phosphosites involved in cell division, cytoskeletal regulation, and microtubule cytoskeleton organization. Integrating predicted and experimentally validated kinases, substrates, and interactors, we reconstructed a phospho-regulatory network that positions PKN1 at the crossroads of cytoskeleton organization and metabolic signaling. To assess the disease relevance of these phosphorylation events, we integrated transcriptomic and phosphoproteomic data from the hepatocellular carcinoma database (HCCDB). PKN1 was markedly up-regulated in HCC, and its phosphorylation at S916 was positively co-regulated with multiple oncogenic and proliferation-associated protein phosphosites. These results predict S562 and S916 as potential sites for targeted biochemical validation and functional experiments. The identification of S562 and S916 as key regulatory sites provides new mechanistic insight into PKN1 activation and highlights potential avenues for therapeutic targeting. Full article

Background: Fibroblast growth factor receptors (FGFRs) play a crucial role in tissue homeostasis and organ development by regulating cellular processes, including proliferation, differentiation, and survival. Dysregulation of FGFRs contributes to developmental disorders and carcinogenesis. As membrane-bound receptors, they represent promising targets for therapeutic intervention and drug development. Methods: This study employed a systematic in silico analysis of publicly available phosphoproteomics datasets to provide a comprehensive overview of the phosphorylation regulatory network of the FGFR family. Results: We identified predominant phosphosites in FGFR1-4 that exhibited differential abundance across diverse experimental conditions, specifically, Y653 in FGFR1; S453, Y586, Y656, and Y657 in FGFR2; S444 and S445 in FGFR3; and S573 in FGFR4. Our analysis identified 32 and 89 significantly co-modulated phosphosites on other proteins with FGFR3 and FGFR4, respectively. Beyond the upstream kinases from the FGFR family, we also identified MAPK1 as a potential upstream kinase of FGFR4. Furthermore, disease enrichment analysis revealed that proteins co-modulated with FGFR3 were primarily involved in skeletal developmental disorders, such as brachydactyly, short toe, and syndactyly of fingers, whereas those associated with FGFR4 were linked to various cancers. Conclusions: Our findings highlight key disease-associated phosphosites within the FGFRs and offer a foundation for advancing phosphosite-focused therapeutic research. Full article

Reversible protein phosphorylation is an important regulatory mechanism in cellular signalling and disease, regulated by the opposing actions of kinases and phosphatases. Modern computer methods predict kinase–substrate or phosphatase–substrate interactions in isolation and lack specificity for biological conditions, neglecting triadic regulation. We present SPINET-KSP, a multi-modal LLM–Graph foundation model engineered for the prediction of kinase–substrate–phosphatase (KSP) triads with contextual awareness. SPINET-KSP integrates high-confidence interactomes (SIGNOR, BioGRID, STRING), structural contacts obtained from AlphaFold3, ESM-3 sequence embeddings, and a 512-dimensional cell-state manifold with 1612 quantitative phosphoproteomic conditions. A heterogeneous KSP graph is examined utilising a cross-attention Graphormer with Reversible Triad Attention to mimic kinase–phosphatase antagonism. SPINET-KSP, pre-trained on 3.41 million validated phospho-sites utilising masked phosphorylation modelling and contrastive cell-state learning, achieves an AUROC of 0.852 for kinase-family classification (sensitivity 0.821, specificity 0.834, MCC 0.655) and a Pearson correlation coefficient of 0.712 for phospho-occupancy prediction. In distinct 2025 mass spectrometry datasets, it identifies 72% of acknowledged cancer-resistance triads within the top 10 rankings and uncovers 247 supplementary triads validated using orthogonal proteomics. SPINET-KSP is the first foundational model for simulating context-dependent reversible phosphorylation, enabling the targeting of dysregulated kinase-phosphatase pathways in diseases. Full article

We developed OmicIntegrator, a broadly adaptable pipeline designed to standardize and integrate publicly available transcriptomic, proteomic, and phosphoproteomic datasets. We applied this workflow to Arabidopsis thaliana etiolated seedlings to identify protein kinases and phosphatases relevant to skotomorphogenic development, a phase during which seedlings rely on tightly regulated signaling networks to ensure survival in darkness. This meta-analysis provided a comprehensive view of gene and protein expression, revealing discrepancies between transcript and protein abundance, suggesting post-transcriptional and post-translational regulation. By integrating multiple datasets, OmicIntegrator reduces experimental bias and enables the detection of phosphorylation events that may be missed in single-condition studies. Distinct phosphorylation patterns were detected across different protein kinase families. Motif enrichment analysis showed a strong overrepresentation of RxxS motifs among phosphosites in protein phosphatases and microtubule-associated proteins, consistent with potential regulation by calcium-dependent protein kinases (CPKs). Across omics layers, CPK3 and CPK9 repeatedly emerged as prominent candidates, highlighting them as priorities for future functional studies in skotomorphogenesis. Overall, our results demonstrate the power of OmicIntegrator as a flexible framework to contextualize signaling landscapes and identify robust patterns and candidate genes and for generating testable hypotheses from integrated multi-omics data in plant developmental biology. Full article

Protein complexes, assembled by scaffold proteins, act as molecular machines driving development. The mechanosensitive adapter protein Zyxin is a key example, integrating actin cytoskeleton dynamics with gene expression. However, the developmental regulation of its interactions and post-translational modifications remains poorly understood. Here, we characterize the dynamic Zyxin interactome across three early developmental stages of Xenopus laevis (from gastrulation to neurulation) using co-immunoprecipitation coupled with quantitative mass spectrometry (DDA and DIA). We identify stage-specific changes in Zyxin’s association with core focal adhesion components, transcriptional regulators and kinases. Furthermore, we uncover developmentally regulated phosphorylation events on isoforms, suggesting dynamic post-translational control of its interactions. Our work provides a comprehensive resource that positions Zyxin as a central orchestrator of cell adhesion, survival, and gene regulatory programs during morphogenesis. These findings underscore the role of Zyxin as a multifaceted regulatory hub, with important implications for understanding tissue homeostasis and related pathologies. Full article

In response to stresses, jasmonates increase rapidly, leading to plant resistance against necrotrophic pathogens and chewing insect herbivores. Jasmonate biosynthesis is regulated at many levels, including transcriptionally, through alternative splicing, and the phosphorylation of the 13S-lipoxygenase (LOX) that catalyzes an early step in jasmonate biosynthesis. In pepper, transcriptomic analysis of a foliar wounding time course was conducted to deepen our understanding of these regulatory mechanisms. All four CaLOXs are constitutively expressed. CaLOX2, which encodes an enzyme with a Ser in a predicted regulatory phosphosite, shows a rapid but short-lived increase in wound-induced expression. In contrast, CaLOX7, which encodes a protein with a non-phosphorylatable Ala at the phosphosite, shows higher wound-induced expression at 6 h. As well, at this timepoint, there is a predicted increase in exon 4 retention in CaLOX8 transcripts in wounded plants. ChimeraX protein modeling predicts that the retention of exon 4 may negatively affect enzyme activity, possibly by blocking access to the enzyme’s active site. The transcription, alternative splicing, and post-translational regulation of CaLOX enzymes support the dynamic fluctuations observed in the jasmonates, which increase rapidly upon wounding and return to basal levels at 6 h post-stress. Full article

FAM20C, previously known as Golgi casein kinase (GCK), is a serine/threonine kinase localized to the Golgi apparatus and classified within the acidophilic kinase family. Its phosphorylation motif is characterized by a glutamic acid residue at the +2 position relative to the target site. Before its molecular identity was established, analysis of a limited number of phosphosites in secreted proteins showed that around 70% matched the GCK consensus sequence, suggesting that GCK is the principal kinase for secreted proteins. Following the identification of GCK as FAM20C, the generation of FAM20C knockout cell lines and phosphoproteomic data confirmed its role: approximately 80% of serine/threonine phosphosites in the secretome of two different human cell lines were shown to depend on FAM20C. In this study, comparative analysis of in vitro phosphorylation datasets from a broad panel of recombinant Ser/Thr kinases confirmed that the FAM20C consensus sequence is distinct from those of other acidophilic kinases. Examination of experimentally identified human phosphosites within the secretory pathway revealed strong conservation of the FAM20C consensus, firmly establishing this enzyme as the master Ser kinase of the entire pathway. From this dataset, we defined the putative FAM20C substratome, comprising 443 phosphosites across 256 proteins, ~77% of which had not been previously linked to FAM20C. This represents the most extensive FAM20C substratome to date and a valuable resource for functional studies. Notably, enrichment analysis highlights strong links between FAM20C and major extracellular pathways, including collagen fibril organization, complement activation, and blood coagulation, underscoring an underappreciated role for this kinase in regulating hemostasis and innate immunity. Full article

The pleiotropic kinase CK2 plays a crucial role in numerous cellular processes and is frequently deregulated in human diseases. Specifically, elevated CK2 expression and/or activity have been observed in human cancers, thus rendering its inhibition a promising pharmacological strategy for treating malignancies. The most widely used CK2 inhibitor, CX-4945 (Silmitarsetib), was developed by Cylene Pharmaceuticals in 2010. It has been tested in clinical trials for various cancers and, more recently, as a potential therapy for COVID-19 patients. However, it has been demonstrated that CX-4945’s specificity is limited, as CX-4945 also inhibits other kinases beyond CK2. A recently developed derivative of CX-4945, SGC-CK2-2, has demonstrated enhanced specificity compared with CX-4945, albeit with reduced potency. In this study, we conducted a detailed analysis of the effects of SGC-CK2-2 in two cancer cell lines, comparing its efficacy with CX-4945 in inhibiting CK2 signaling and in cell death induction. The findings of this study demonstrate the differential sensitivity of CK2 phospho-substrates to these inhibitors, thus indicating that complete inhibition of a single phosphosite, such as S129 Akt, is insufficient to fully suppress CK2 signaling. Furthermore, the results suggest that partial CK2 inhibition with the suppression of the most sensitive phosphosites does not significantly impact cell viability, while a near-complete suppression of CK2 signaling affects cell viability and leads to cell death induction. Full article

Extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitors show therapeutic potential in triple-negative breast cancer (TNBC), but resistance through compensatory signaling limits their efficacy. We previously identified the secretory carrier membrane protein 3 (SCAMP3) as a regulator of TNBC progression and ERK1/2 activation. Here, we investigated the role of SCAMP3 in ERK1/2 signaling and therapeutic response using TMT-based LC-MS/MS phosphoproteomics of wild-type (WT) and SCAMP3 knockout (SC3KO) SUM-149 cells under basal conditions, after epidermal growth factor (EGF) stimulation, and during ERK1/2 inhibition with MK-8353. A total of 4408 phosphosites were quantified, with 1093 significantly changed. SC3KO abolished residual ERK activity under MK-8353 and affected the compensatory activation of oncogenic pathways observed in WT cells. SC3KO reduced the phosphorylation of ERK feedback regulators RAF proto-oncogene serine/threonine-protein kinase Raf-1 (S43) and the dual-specificity mitogen-activated protein kinase kinase 2 (MEK2) (T394), affected other ERK targets, including nucleoporins, transcription factors, and metabolic enzymes triosephosphate isomerase (TPI1) (S21) and ATP-citrate lyase (ACLY) (S455). SCAMP3 loss also impaired the mammalian target of rapamycin complex I (mTORC1) signaling and disrupted autophagic flux, evidenced by elevated sequestosome-1 (SQSTM1/p62) and microtubule-associated protein light chain 3 (LC3B-II) with reduced levels of the autophagosome lysosome maturation marker, Rab7A. Beyond ERK substrates, SC3KO affected phosphorylation events mediated by other kinases. These findings position SCAMP3 as a central coordinator of ERK signaling and autophagy. Our results support SCAMP3 as a potential therapeutic target to enhance ERK1/2 inhibitor clinical efficacy and overcome adaptive resistance mechanisms in TNBC. Full article

The TP53 gene, frequently mutated across multiple cancer types, plays a pivotal role in regulating the cell cycle and apoptosis through its protein, p53. Missense variants of uncertain significance (VUSs) in TP53 present challenges in understanding their impact on protein function and complicate clinical interpretation. This study aims to analyze the effects of missense VUSs in p53, as reported in the gnomAD database, with a specific focus on their impact on protein stability and phosphorylation. In this study, 33 missense VUSs in TP53 reported in the gnomAD database were analyzed using in silico tools, including PhosphositePlus v6.7.4, the Kinase Library v0.0.11, and Dynamut2. Of these analyzed variants, five disrupted known phosphorylation sites, while another five created new consensus sequences for phosphorylation. Moreover, 20 variants exhibited a moderate destabilizing effect on the protein structure. At least three missense VUSs were identified as potentially affecting p53 function, which may contribute to cancer development. These findings highlight the importance of integrating in silico structural and functional analysis to assess the pathogenic potential of missense VUSs. Full article

Acinetobacter baumannii is a multidrug-resistant bacterium that has gained significant attention in recent years due to its involvement in a growing number of hospital-acquired infections. The World Health Organization has classified it as a critical priority pathogen, underscoring the urgent need for new therapeutic strategies. Post-translational modifications (PTMs), such as phosphorylation, play essential roles in various bacterial processes, including antibiotic resistance, virulence or biofilm formation. Although proteomics has increasingly enabled their characterization, the identification of phosphorylated peptides remains challenging, primarily due to the enrichment procedures. In this study, we focused on characterizing serine, threonine, and tyrosine phosphorylation in the A. baumannii ATCC 17978 strain. We optimized three parameters for phosphopeptide enrichment using titanium dioxide (TiO₂) beads (number of enrichment fractions between the phosphopeptides and TiO₂ beads, the quantity peptides and type of loading buffer) to determine the most effective conditions for maximizing phosphopeptide identification. Using this optimized protocol, we identified 384 unique phosphorylation sites across 241 proteins, including 260 novel phosphosites previously unreported in A. baumannii. Several of these phosphorylated proteins are involved in critical bacterial processes such as antimicrobial resistance, biofilm formation or pathogenicity. We discuss these proteins, focusing on the potential functional implications of their phosphorylation. Notably, we identified 34 phosphoproteins with phosphosites localized at functional sites, such as active sites, multimer interfaces, or domains important for structural integrity. Our findings significantly expand the current phosphoproteomic landscape of A. baumannii and support the hypothesis that PTMs, particularly phosphorylation, play a central regulatory role in its physiology and pathogenic potential. Full article

Salinity is one of the major factors limiting the growth, development, and yield of cotton. Although the mechanisms of cotton tolerance to salt stress have been studied, the regulatory roles and mechanisms of protein kinases and phosphatases in cotton salt response remain poorly understood. Here, we identify Type One Protein Phosphatase 4aD (GhTOPP4aD), belonging to the Type One Protein Phosphatase (TOPP) family, as a negative regulator in cotton salt stress response. To reveal the post-translational modification mechanism by which GhTOPP4aD regulates salt stress response in cotton, phosphoproteome analysis was performed. A total of 6055 phosphoproteins with 12,608 phosphosites were identified. In VIGS-Ctrl plants, there were 935 upregulated and 35 downregulated phosphoproteins, while there were 1026 upregulated and 89 downregulated phosphoproteins in VIGS-GhTOPP4aD plants after NaCl treatment. Moreover, a class of tyrosine kinases responsive to abscisic acid (ABA) was significantly enriched at upregulated, differentially phosphorylated sites that were induced by NaCl in GhTOPP4aD-silenced plants, suggesting that these proteins could be regulated by dephosphorylation mediated by GhTOPP4aD in response to salt stress. Among them, Raf-like Kinase 36 (GhRAF36), FERONIA (GhFER), and Lysin Motif-containing Receptor-like Kinase 3 (GhLYK3) interacted with GhTOPP4aD and their kinase activities were inhibited by GhTOPP4aD. VIGS-GhRAF36, VIGS-GhFER, and VIGS-GhLYK3 plants were sensitive to salt stress, suggesting that these kinases may play important roles in the regulation of cotton salt stress response mediated by GhTOPP4aD. These studies provide new insights into the mechanisms of cotton salt stress tolerance and the potential molecular targets for breeding salt-tolerant cotton varieties. Full article

Rapid ascent to high altitudes by unacclimatized individuals significantly increases the risk of brain damage, given the brain’s heightened sensitivity to hypoxic conditions. Investigating hypoxia-tolerant animals can provide insights into adaptive mechanisms and guide prevention and treatment of hypoxic-ischemic brain injury. In this study, we exposed Brandt’s voles to simulated altitudes (100 m, 3000 m, 5000 m, and 7000 m) for 24 h and performed quantitative proteomic and phosphoproteomic analyses of brain tissue. A total of 3990 proteins and 9125 phosphorylation sites (phospho-sites) were quantified. Differentially expressed (DE) analysis revealed that while protein abundance changes were relatively modest, phosphorylation levels exhibited substantial alterations, suggesting that Brandt’s voles rapidly regulate protein structure and function through phosphorylation to maintain cellular homeostasis under acute hypoxia. Clustering analysis showed that most co-expressed proteins exhibited non-monotonic responses with increasing altitude, which were enriched in pathways related to cytokine secretion regulation and glutathione metabolism, contributing to reduced inflammation and oxidative stress. In contrast, most co-expressed phospho-sites showed monotonic changes, with phospho-proteins enriched in glycolysis and vascular smooth muscle contraction regulation. Kinase activity prediction identified nine hypoxia-responsive kinases, four of which belonging to the CAMK family. Immunoblot validated that the changes in CAMK2A activity were consistent with predictions, suggesting that CAMK may play a crucial role in hypoxic response. In conclusion, this work discovered that Brandt’s voles may cope with hypoxia through three key strategies: (1) vascular regulation to enhance cerebral blood flow, (2) glycolytic activation to increase energy production, and (3) activation of neuroprotective mechanisms. Full article