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2,107 result(s) for "Regulatory subunits"
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Protein kinase CK2 in breast cancer: the CK2β regulatory subunit takes center stage in epithelial plasticity
Structurally, protein kinase CK2 consists of two catalytic subunits (α and α′) and two regulatory subunits (β), which play a critical role in targeting specific CK2 substrates. Compelling evidence shows the complexity of the CK2 cellular signaling network and supports the view that this enzyme is a key component of regulatory protein kinase networks that are involved in several aspects of cancer. CK2 both activates and suppresses the expression of a number of essential oncogenes and tumor suppressors, and its expression and activity are upregulated in blood tumors and virtually all solid tumors. The prognostic significance of CK2α expression in association with various clinicopathological parameters highlighted this kinase as an adverse prognostic marker in breast cancer. In addition, several recent studies reported its implication in the regulation of the epithelial-to-mesenchymal transition (EMT), an early step in cancer invasion and metastasis. In this review, we briefly overview the contribution of CK2 to several aspects of cancer and discuss how in mammary epithelial cells, the expression of its CK2β regulatory subunit plays a critical role in maintaining an epithelial phenotype through CK2-mediated control of key EMT-related transcription factors. Importantly, decreased CK2β expression in breast tumors is correlated with inefficient phosphorylation and nuclear translocation of Snail1 and Foxc2, ultimately leading to EMT induction. This review highlights the pivotal role played by CK2β in the mammary epithelial phenotype and discusses how a modest alteration in its expression may be sufficient to induce dramatic effects facilitating the early steps in tumor cell dissemination through the coordinated regulation of two key transcription factors.
Enhanced multi-stress tolerance and glucose utilization of Saccharomyces cerevisiae by overexpression of the SNF1 gene and varied beta isoform of Snf1 dominates in stresses
Background The Saccharomyces cerevisiae Snf1 complex is a member of the AMP-activated protein kinase family and plays an important role in response to environmental stress. The α catalytic subunit Snf1 regulates the activity of the protein kinase, while the β regulatory subunits Sip1/Sip2/Gal83 specify substrate preferences and stress response capacities of Snf1. In this study, we aim to investigate the effects of SNF1 overexpression on the cell tolerance and glucose consumption of S. cerevisiae in high glucose, ethanol, and heat stresses and to explore the valid Snf1 form in the light of β subunits in these stresses. Results The results suggest that overexpression of SNF1 is effective to improve cell resistance and glucose consumption of S. cerevisiae in high glucose, ethanol, and heat stresses, which might be related to the changed accumulation of fatty acids and amino acids and altered expression levels of genes involved in glucose transport and glycolysis. However, different form of β regulatory subunits dominated in stresses with regard to cell tolerance and glucose utilization. The Sip1 isoform was more necessary to the growth and glucose consumption in ethanol stress. The glucose uptake largely depended on the Sip2 isoform in high sugar and ethanol stresses. The Gal83 isoform only contributed inferior effect on the growth in ethanol stress. Therefore, redundancy and synergistic effect of β subunits might occur in high glucose, ethanol, and heat stresses, but each subunit showed specificity under various stresses. Conclusions This study enriches the understanding of the function of Snf1 protein kinase and provides an insight to breed multi-stress tolerant yeast strains.
Leucine Carboxyl Methyltransferase Downregulation and Protein Phosphatase Methylesterase Upregulation Contribute Toward the Inhibition of Protein Phosphatase 2A by α-Synuclein
The pathology of Parkinson's disease (PD) is characterized by intracellular neurofibrillary tangles of phosphorylated α-synuclein (α-syn). Protein phosphatase 2A (PP2A) is responsible for α-syn dephosphorylation. Previous work has demonstrated that α-syn can regulate PP2A activity. However, the mechanisms underlying α-syn regulation of PP2A activity are not well understood. In this study, we found that α-syn overexpression induced increased α-syn phosphorylation at serine 129 (Ser129), and PP2A inhibition, and . α-syn overexpression resulted in PP2A demethylation. This demethylation was mediated via downregulated leucine carboxyl methyltransferase (LCMT-1) expression, and upregulated protein phosphatase methylesterase (PME-1) expression. Furthermore, LCMT-1 overexpression, or PME-1 inhibition, reversed α-syn-induced increases in α-syn phosphorylation and apoptosis. In addition to post-translational modifications of the catalytic subunit, regulatory subunits are involved in the regulation of PP2A activity. We found that the levels of regulatory subunits which belong to the subfamily, not the subfamily, were downregulated in the examined brain regions of transgenic mice. Our work identifies a novel mechanism to explain how α-syn regulates PP2A activity, and provides the optimization of PP2A methylation as a new target for PD treatment.
MiR-126-3p inhibits apoptosis and promotes proliferation by targeting phosphatidylinositol 3-kinase regulatory subunit 2 in porcine ovarian granulosa cells
Objective: Numerous studies have indicated that the apoptosis and proliferation of granulosa cells (GCs) are closely related to the normal growth and development of follicles and ovaries. Previous evidence has suggested that miR-126-3p might get involved in the apoptosis and proliferation of GCs, and phosphatidylinositol 3-kinase regulatory subunit 2 (PIK3R2) gene has been predicted as one target of miR-126-3p. However, the molecular regulation of miR-126-3p on PIK3R2 and the effects of PIK3R2 on porcine GCs apoptosis and proliferation remain virtually unexplored. Methods: In this study, using porcine GCs as a cellular model, luciferase report assay, mutation and deletion were applied to verify the targeting relationship between miR-126-3p and PIK3R2. Annexin-V/PI staining and 5-ethynyl-2’-deoxyuridine assay were applied to explore the effect of PIK3R2 on GCs apoptosis and proliferation, respectively. Real-time quantitative polymerase chain reaction and Western Blot were applied to explore the regulation of miR-126-3p on PIK3R2 expression. Results: We found that miR-126-3p targeted at PIK3R2 and inhibited its mRNA and protein expression. Knockdown of PIK3R2 significantly inhibited the apoptosis and promoted the proliferation of porcine GCs, and significantly down-regulated the mRNA expression of several key genes of PI3K pathway such as insulin-like growth factor 1 receptor (IGF1R), insulin receptor (INSR), pyruvate dehydrogenase kinase 1 (PDK1), and serine/threonine kinase 1 (AKT1). Conclusion: MiR-126-3p might target and inhibit the mRNA and protein expressions of PIK3R2, thereby inhibiting GC apoptosis and promoting GC proliferation by down-regulating several key genes of the PI3K pathway, IGF1R, INSR, PDK1, and AKT1. These findings would provide great insight into further exploring the molecular regulation of miR-126-3p and PIK3R2 on the functions of GCs during the folliculogenesis in female mammals. KCI Citation Count: 6
Macrophage–Derived Ferritin Exacerbates Silica‐Induced Pulmonary Fibrosis via PIK3R2‐Mediated Fibroblast Differentiation
Silicosis is a progressive and life‐threatening fibrotic lung disease caused by crystalline silica. However, targeted therapies remain unavailable due to its incompletely understood pathogenic mechanisms. Here, we identify ferritin as a pivotal mediator of silica‐induced pulmonary fibrosis by integrating clinical exploration with experimental validation. We detected persistently elevated ferritin levels in lung tissues and serum from silicosis patients and silica‐exposed mice, and demonstrated that exogenous ferritin administration exacerbates fibrosis in vivo. Multi‐omics profiling and co‐culture experiments revealed that macrophage–secreted ferritin promotes fibroblast‐to‐myofibroblast differentiation and pathological extracellular matrix (ECM) deposition via the PIK3R2/SMAD signaling axis. Importantly, genetic knockdown of ferritin in macrophages significantly suppressed myofibroblast differentiation and collagen accumulation both in vivo and in vitro. These findings underscore that ferritin functions not only as a potential clinical biomarker for silicosis surveillance but also as a pathogenic driver through macrophage‐fibroblast crosstalk, and provide a theoretical foundation for developing integrated diagnostic and therapeutic strategies against silicosis. This study identifies ferritin as a pivotal mediator of silica‐induced pulmonary fibrosis. Macrophage‐derived ferritin drives fibroblast‐to‐myofibroblast differentiation via the PIK3R2/SMAD pathway, while ferritin knockdown alleviates fibrosis. These findings define ferritin as both a biomarker and pathogenic driver, highlighting ferritin‐PIK3R2 signaling axis as a promising cross‐cellular therapeutic target for silicosis.
Enhanced AKT Phosphorylation of Circulating B Cells in Patients With Activated PI3Kδ Syndrome
Activated PI3Kδ syndrome (APDS) is a primary immunodeficiency characterized by recurrent respiratory tract infections, lymphoproliferation, and defective IgG production. Heterozygous mutations in , or , which are related to the hyperactive phosphoinositide 3-kinase (PI3K) signaling, were recently presented to cause APDS1 or APDS2 (APDSs), or APDS-like (APDS-L) disorder. In this study, we examined the AKT phosphorylation of peripheral blood lymphocytes and monocytes in patients with APDSs and APDS-L by using flow cytometry. CD19 B cells of peripheral blood in APDS2 patients showed the enhanced phosphorylation of AKT at Ser473 (pAKT) without any specific stimulation. The enhanced pAKT in CD19 B cells was normalized by the addition of a p110δ inhibitor. In contrast, CD3 T cells and CD14 monocytes did not show the enhanced pAKT in the absence of stimulation. These findings were similarly observed in patients with APDS1 and APDS-L. Among CD19 B cells, enhanced pAKT was prominently detected in CD10 immature B cells compared with CD10 mature B cells. Enhanced pAKT was not observed in B cells of healthy controls, patients with common variable immunodeficiency, and hyper IgM syndrome due to CD40L deficiency. These results suggest that the enhanced pAKT in circulating B cells may be useful for the discrimination of APDS1, APDS2, and APDS-L from other antibody deficiencies.
MicroRNA-411 inhibits malignant biological behaviours of colorectal cancer cells by directly targeting PIK3R3
Colorectal cancer (CRC) is the third most common cancer and the fourth leading cause of cancer-related mortality worldwide. Aberrant expression of miRNAs play important roles in the development and progression of various types of cancers by modulating oncogenic and tumour-suppressor pathways. Therefore, exploring the functions of microRNAs (miRNAs) that specifically contribute to CRC tumourigenesis and tumour development would greatly aid in obtaining more information on CRC and provide new targets for its diagnosis and treatment. miRNA-411 (miR-411) was previously observed to be aberrantly expressed in multiple human cancers. However, the expression pattern, function and underlying molecular mechanism of miR-411 in CRC remain unclear. Therefore, the present study was performed to detect miR-411 expression, investigate the biological roles of miR-411 and identify its mechanism of action in CRC cells. Here, miR-411 expression was significantly downregulated in human CRC tissues and cell lines, and low levels of miR-411 were correlated with lymph node metastasis, distant metastasis and TNM stage. Resumed expression of miR-411 suppressed cell proliferation and invasion but promoted apoptosis in CRC. Additionally, phosphoinositide-3-kinase regulatory subunit 3 (PIK3R3) was identified as a direct target of miR-411 in CRC. PIK3R3 was upregulated in the CRC tissues and inversely correlated with miR-411 expression. Downregulation of PIK3R3 had tumour-suppressive effects similar to those of miR-411 overexpression in CRC. Moreover, upregulation of PIK3R3 could rescue the tumour-suppressing effects of miR-411 overexpression in CRC cells. More importantly, miR-411 specifically suppressed the activation of the AKT/mTOR signalling pathway in CRC. Therefore, miR-411 functions as a tumour-suppressive miRNA by directly targeting PIK3R3 and indirectly regulating AKT/mTOR signalling pathway. miR-411 may serve as a new therapeutic target for patients with CRC.
Unveiling CKS2: A Key Player in Aggressive B‐Cell Lymphoma Progression and a Target for Synergistic Therapy
Background The objective of this study was to investigate the expression levels and biological significance of CKS2 in Burkitt cell lymphoma (BL) and diffuse large B‐cell lymphoma (DLBCL). Additionally, the potential synergistic anti‐tumor effects of CKS2 knockdown in combination with etoposide in BL and DLBCL were explored for the first time. Methods Bioinformatics analysis was utilized to explore the transcriptional levels, prognostic value, and gene function enrichment of CKS2 in BL and DLBCL. Specific shRNA sequences were designed to target CKS2 for the purpose of constructing a lentiviral expression vector, and therapeutic effects were assessed through analyses of cell proliferation, cell cycle distribution, and cell apoptosis. Results First, the study examined the increased transcriptional and protein levels of CKS2 in BL and DLBCL through analysis of various databases and immunohistochemistry tests. Elevated CKS2 expression was found to be correlated with a worse prognosis in BL and DLBCL patients, as evidenced by data from the TCGA and GEO databases. Enrichment analysis indicated that CKS2 functions were primarily linked to protein kinase regulatory activity, G1/S phase transition of the cell cycle, and the p53 signaling pathway, among others. Second, stable suppression of CKS2 gene expression in Raji and SUDHL6 cells using shRNA resulted in a significant inhibition of cell proliferation. Moreover, CKS2‐shRNA induced G0/G1 cell cycle arrest and apoptosis by activating the p53 signaling pathway in Raji and SUDHL6 cells. Third, the combined treatment of CKS2‐shRNA and etoposide exhibited a synergistic effect on the proliferation and apoptosis of Raji and SUDHL6 cells. Conclusions Our findings suggest that CKS2 may play a critical role in the progression of BL and DLBCL and provide evidence for the potential therapeutic application of combining CKS2‐shRNA and etoposide agents in the treatment of BL and DLBCL.
A guide to selecting high-performing antibodies for Serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit delta isoform (PPP2R5D) for use in Western Blot, immunoprecipitation and immunofluorescence version 2; peer review: 1 approved with reservations
Protein phosphatase 2A is a serine/threonine phosphatase with activity dependent on an associated regulatory subunit, serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit delta (δ) isoform (PPP2R5D). PPP2R5D is the δ isoform in the B56 family of regulatory subunits. Abundantly expressed in the brain and involved in a broad range of cellular processes, PPP2R5D plays an essential role in modulating key neuronal pathways and signalling. Pathogenic mutations in the PPP2R5D gene are linked to clinical symptoms characterized by neurodevelopmental delay, intellectual disability, and autism spectrum disorders. The etiology of these genetic disorders remains unknown, which can partly be due to the lack of independently characterized antibodies. Here we have characterized six PPP2R5D commercial antibodies for Western Blot, immunoprecipitation, and immunofluorescence using a standardized experimental protocol based on comparing read-outs in knockout cell lines and isogenic parental controls. These studies are part of a larger, collaborative initiative seeking to address antibody reproducibility by characterizing commercially available antibodies for human proteins and publishing the results openly as a resource for the scientific community. While use of antibodies and protocols vary between laboratories, we encourage readers to use this report as a guide to select the most appropriate antibodies for their specific needs.
Comparative Analysis and Molecular Evolution of Class I PI3K Regulatory Subunit p85α Reveal the Structural Similarity Between nSH2 and cSH2 Domains
Phosphoinositide 3-kinase (PI3K) is an essential regulatory protein of the insulin signaling pathway and several other pathways that govern cell survival, cell proliferation, cell differentiation and oncogene regulation. The protein has main two subunits; regulatory p85 and catalytic p110. Other regulatory subunits are p50, p55. The catalytic activity of p110 is stabilized by the regulatory subunit p85α. This regulatory subunit is composed of five domains; the SH3, BCR-homology (BH), N-terminal SH2 (nSH2), C-terminal SH2 (cSH2), and inter-SH2 (iSH2). In the current study, we executed comparative analysis of the computational proteomic and molecular evolution of these five domains. Our results reveal that faster and more cost-effective methods for forming intricate relationships between the domains are worth pursuing according to vital proteomic parameters such as physico-chemical properties, evolution and post-translational modification (PTM). The results show variation instability, grand average of hydrophobicity (GRAVY), aliphatic index, globularity, PTM among the five domains, and strongly indicate a likeness between the nSH2 and cSH2 domains. The study provides vital information for the structural and functional aspects of PI3K regulatory subunit p85α. Many of these property changes might be defined as protein–protein interactions, protein folding structures and structure–function correlations in future.