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Cell Stress & Chaperones Jun 2024Heart failure (HF) refers to a group of clinical syndromes in which various heart diseases lead to the inability of cardiac output to meet the metabolic needs of the... (Review)
Review
Heart failure (HF) refers to a group of clinical syndromes in which various heart diseases lead to the inability of cardiac output to meet the metabolic needs of the body's tissues. Cardiac metabolism requires enormous amounts of energy; thus, impaired myocardial energy metabolism is considered a key factor in the occurrence and development of HF. Mitochondria serve as the primary energy source for cardiomyocytes, and their regular functionality underpins healthy cardiac function. The mitochondrial quality control system is a crucial mechanism for regulating the functionality of cardiomyocytes, and any abnormality in this system can potentially impact the morphology and structure of mitochondria, as well as the energy metabolism of cardiomyocytes. Phosphoglycerate mutase 5 (PGAM5), a multifunctional protein, plays a key role in the regulation of mitochondrial quality control through multiple pathways. Therefore, abnormal PGAM5 function is closely related to mitochondrial damage. This article reviews the mechanism of PGAM5's involvement in the regulation of the mitochondrial quality control system in the occurrence and development of HF, thereby providing a theoretical basis for future in-depth research.
Topics: Humans; Heart Failure; Animals; Mitochondria, Heart; Phosphoprotein Phosphatases; Mitochondrial Proteins; Myocytes, Cardiac; Mitochondria; Energy Metabolism
PubMed: 38821173
DOI: 10.1016/j.cstres.2024.05.004 -
Science Advances May 2024PR65 is the HEAT repeat scaffold subunit of the heterotrimeric protein phosphatase 2A (PP2A) and an archetypal tandem repeat protein. Its conformational mechanics plays...
PR65 is the HEAT repeat scaffold subunit of the heterotrimeric protein phosphatase 2A (PP2A) and an archetypal tandem repeat protein. Its conformational mechanics plays a crucial role in PP2A function by opening/closing substrate binding/catalysis interface. Using in silico saturation mutagenesis, we identified PR65 "hinge" residues whose substitutions could alter its conformational adaptability and thereby PP2A function, and selected six mutations that were verified to be expressed and soluble. Molecular simulations and nanoaperture optical tweezers revealed consistent results on the specific effects of the mutations on the structure and dynamics of PR65. Two mutants observed in simulations to stabilize extended/open conformations exhibited higher corner frequencies and lower translational scattering in experiments, indicating a shift toward extended conformations, whereas another displayed the opposite features, confirmed by both simulations and experiments. The study highlights the power of single-molecule nanoaperture-based tweezers integrated with in silico approaches for exploring the effect of mutations on protein structure and dynamics.
Topics: Optical Tweezers; Molecular Dynamics Simulation; Point Mutation; Protein Conformation; Protein Phosphatase 2; Humans
PubMed: 38820156
DOI: 10.1126/sciadv.adn2208 -
International Journal of Medical... 2024This study aims to elucidate the roles of Phosphoglycerate Mutase Family Member 5 (Pgam5) and Prohibitin 2 (Phb2) in the context of hyperglycemia-induced myocardial...
This study aims to elucidate the roles of Phosphoglycerate Mutase Family Member 5 (Pgam5) and Prohibitin 2 (Phb2) in the context of hyperglycemia-induced myocardial dysfunction, a critical aspect of diabetic cardiomyopathy. The research employed primary cardiomyocytes, which were then subjected to hyperglycemia treatment to mimic diabetic conditions. We used siRNA transfection to knock down Pgam5 and overexpressed Phb2 using adenovirus transfection to assess their individual and combined effects on cardiomyocyte health. Mitochondrial function was evaluated through measurements of mitochondrial membrane potential using the JC-1 probe, and levels of mitochondrial reactive oxygen species (ROS) were assessed. Additionally, the study involved qPCR analysis to quantify the transcriptional changes in genes related to mitochondrial fission and mitophagy. Our findings indicate that hyperglycemia significantly reduces cardiomyocyte viability and impairs mitochondrial function, as evidenced by decreased mitochondrial membrane potential and increased ROS levels. Pgam5 knockdown was observed to mitigate these adverse effects, preserving mitochondrial function and cardiomyocyte viability. On the molecular level, Pgam5 was found to regulate genes associated with mitochondrial fission (such as Drp1, Mff, and Fis1) and mitophagy (including Parkin, Bnip3, and Fundc1). Furthermore, overexpression of Phb2 countered the hyperglycemia-induced mitochondrial dysfunction and normalized the levels of key mitochondrial antioxidant enzymes. The combined data suggest a protective role for both Pgam5 knockdown and Phb2 overexpression against hyperglycemia-induced cellular and mitochondrial damage. The study elucidates the critical roles of Pgam5 and Phb2 in regulating mitochondrial dynamics in the setting of hyperglycemia-induced myocardial dysfunction. By modulating mitochondrial fission and mitophagy, Pgam5 and Phb2 emerge as key players in preserving mitochondrial integrity and cardiomyocyte health under diabetic conditions. These findings contribute significantly to our understanding of the molecular mechanisms underlying diabetic cardiomyopathy and suggest potential therapeutic targets for mitigating myocardial dysfunction in diabetes.
Topics: Prohibitins; Myocytes, Cardiac; Mitochondrial Dynamics; Hyperglycemia; Humans; Membrane Potential, Mitochondrial; Diabetic Cardiomyopathies; Reactive Oxygen Species; Animals; Mitophagy; Phosphoprotein Phosphatases; Repressor Proteins; Mitochondria, Heart; Mitochondrial Proteins; Rats
PubMed: 38818468
DOI: 10.7150/ijms.92872 -
World Journal of Gastroenterology May 2024Cell division cyclin 25C () is a protein that plays a critical role in the cell cycle, specifically in the transition from the G2 phase to the M phase. Recent research...
BACKGROUND
Cell division cyclin 25C () is a protein that plays a critical role in the cell cycle, specifically in the transition from the G2 phase to the M phase. Recent research has shown that could be a potential therapeutic target for cancers, particularly for hepatocellular carcinoma (HCC). However, the specific regulatory mechanisms underlying the role of in HCC tumorigenesis and development remain incompletely understood.
AIM
To explore the impact of on cell proliferation and apoptosis, as well as its regulatory mechanisms in HCC development.
METHODS
Hepa1-6 and B16 cells were transduced with a lentiviral vector containing shRNA interference sequences (LV- shRNA) to knock down . Subsequently, a xenograft mouse model was established by subcutaneously injecting transduced Hepa1-6 cells into mice to assess the effects of knockdown on HCC development . Cell proliferation and migration were evaluated using a Cell Counting Kit-8 cell proliferation assays and wound healing assays, respectively. The expression of endoplasmic reticulum (ER) stress-related molecules (glucose-regulated protein 78, X-box binding protein-1, and C/EBP homologous protein) was measured in both cells and subcutaneous xenografts using quantitative real-time PCR (qRT-PCR) and western blotting. Additionally, apoptosis was investigated using flow cytometry, qRT-PCR, and western blotting.
RESULTS
was stably suppressed in Hepa1-6 and B16 cells through LV- shRNA transduction. A xenograft model with knockdown was successfully established and that downregulation of expression significantly inhibited HCC growth in mice. knockdown not only inhibited cell proliferation and migration but also significantly increased the ER stress response, ultimately promoting ER stress-induced apoptosis in HCC cells.
CONCLUSION
The regulatory mechanism of in HCC development may involve the activation of ER stress and the ER stress-induced apoptosis signaling pathway.
Topics: Animals; Endoplasmic Reticulum Stress; Carcinoma, Hepatocellular; Cell Proliferation; cdc25 Phosphatases; Apoptosis; Liver Neoplasms; Cell Line, Tumor; Mice; Gene Knockdown Techniques; Cell Movement; Mice, Inbred C57BL; Humans; RNA, Small Interfering; Male; Gene Expression Regulation, Neoplastic; Xenograft Model Antitumor Assays; Carcinogenesis
PubMed: 38817663
DOI: 10.3748/wjg.v30.i19.2564 -
Neuroreport Jul 2024Hyperactivation of the Ca2+/calmodulin-dependent phosphatase calcineurin (CN) is observed in reactive astrocytes associated with neuroinflammation and progressive...
Hyperactivation of the Ca2+/calmodulin-dependent phosphatase calcineurin (CN) is observed in reactive astrocytes associated with neuroinflammation and progressive degenerative diseases, like Alzheimer's disease. Apart from key transcription factors (e.g. nuclear factor of activated t cells and nuclear factor-κB) very few other CN-dependent pathways have been studied in astrocytes. The hemichannel protein, connexin 43 (Cx43) is found at high levels in astrocytes and contains a CN-sensitive Ser residue near its carboxy terminus. CN-dependent dephosphorylation of Cx43 has been reported in primary astrocytes treated with injurious stimuli, but much remains unknown about CN/Cx43 interactions in the context of neuroinflammation and disease. Western blots were used to assess total Cx43 and dephosphorylated Cx43 subtypes in rat embryonic primary astrocytes treated with a hyperactive CN fragment (ΔCN, via adenovirus), or with a proinflammatory cytokine cocktail. Under similar treatment conditions, an ethidium bromide (EtBr) uptake assay was used to assess membrane permeability. Effects of ΔCN and cytokines were tested in the presence or absence of the CN inhibitor, cyclosporin A. A connexin inhibitor, carbenoxolone was also used in EtBr assays to assess the involvement of connexins in membrane permeability. Treatment with ΔCN or cytokines increased dephosphorylated Cx43 levels in conjunction with increased membrane permeability (elevated EtBr uptake). Effects of ΔCN or cytokine treatment were blocked by cyclosporine A. Treatment-induced changes in EtBr uptake were also inhibited by carbenoxolone. The results suggest that Cx43 hemichannels could be an important mechanism through which astrocytic CN disrupts neurologic function associated with neurodegenerative disease.
Topics: Astrocytes; Connexin 43; Animals; Phosphorylation; Calcineurin; Rats; Cell Membrane Permeability; Cells, Cultured; Rats, Sprague-Dawley
PubMed: 38813906
DOI: 10.1097/WNR.0000000000002051 -
BMC Biology May 2024The innate immune system serves as the first line of host defense. Transforming growth factor-β-activated kinase 1 (TAK1) is a key regulator of innate immunity, cell...
BACKGROUND
The innate immune system serves as the first line of host defense. Transforming growth factor-β-activated kinase 1 (TAK1) is a key regulator of innate immunity, cell survival, and cellular homeostasis. Because of its importance in immunity, several pathogens have evolved to carry TAK1 inhibitors. In response, hosts have evolved to sense TAK1 inhibition and induce robust lytic cell death, PANoptosis, mediated by the RIPK1-PANoptosome. PANoptosis is a unique innate immune inflammatory lytic cell death pathway initiated by an innate immune sensor and driven by caspases and RIPKs. While PANoptosis can be beneficial to clear pathogens, excess activation is linked to pathology. Therefore, understanding the molecular mechanisms regulating TAK1 inhibitor (TAK1i)-induced PANoptosis is central to our understanding of RIPK1 in health and disease.
RESULTS
In this study, by analyzing results from a cell death-based CRISPR screen, we identified protein phosphatase 6 (PP6) holoenzyme components as regulators of TAK1i-induced PANoptosis. Loss of the PP6 enzymatic component, PPP6C, significantly reduced TAK1i-induced PANoptosis. Additionally, the PP6 regulatory subunits PPP6R1, PPP6R2, and PPP6R3 had redundant roles in regulating TAK1i-induced PANoptosis, and their combined depletion was required to block TAK1i-induced cell death. Mechanistically, PPP6C and its regulatory subunits promoted the pro-death S166 auto-phosphorylation of RIPK1 and led to a reduction in the pro-survival S321 phosphorylation.
CONCLUSIONS
Overall, our findings demonstrate a key requirement for the phosphatase PP6 complex in the activation of TAK1i-induced, RIPK1-dependent PANoptosis, suggesting this complex could be therapeutically targeted in inflammatory conditions.
Topics: Receptor-Interacting Protein Serine-Threonine Kinases; Humans; Phosphoprotein Phosphatases; MAP Kinase Kinase Kinases; Necroptosis; Immunity, Innate
PubMed: 38807188
DOI: 10.1186/s12915-024-01901-5 -
Open Biology May 2024The precise spatial and temporal control of histone phosphorylations is important for the ordered progression through the different phases of mitosis. The...
The precise spatial and temporal control of histone phosphorylations is important for the ordered progression through the different phases of mitosis. The phosphorylation of H2B at S6 (H2B S6ph), which is crucial for chromosome segregation, reaches its maximum level during metaphase and is limited to the inner centromere. We discovered that the temporal and spatial regulation of this modification, as well as its intensity, are governed by the scaffold protein RepoMan and its associated catalytically active phosphatases, PP1α and PP1γ. Phosphatase activity is inhibited at the area of maximal H2B S6 phosphorylation at the inner centromere by site-specific Aurora B-mediated inactivation of the PP1/RepoMan complex. The motor protein Mklp2 contributes to the relocalization of Aurora B from chromatin to the mitotic spindle during anaphase, thus alleviating Aurora B-dependent repression of the PP1/RepoMan complex and enabling dephosphorylation of H2B S6. Accordingly, dysregulation of Mklp2 levels, as commonly observed in tumour cells, leads to the lack of H2B S6 dephosphorylation during early anaphase, which might contribute to chromosomal instability.
Topics: Aurora Kinase B; Phosphorylation; Humans; Histones; Mitosis; Protein Phosphatase 1; Cell Cycle Proteins; HeLa Cells; Spindle Apparatus; Centromere; Nuclear Proteins
PubMed: 38806145
DOI: 10.1098/rsob.230460 -
Life Science Alliance Aug 2024FK506-binding protein 52 (FKBP52) is a member of the FKBP family of proline isomerases. FKBP52 is up-regulated in various cancers and functions as a positive regulator...
FK506-binding protein 52 (FKBP52) is a member of the FKBP family of proline isomerases. FKBP52 is up-regulated in various cancers and functions as a positive regulator of steroid hormone receptors. Depletion of FKBP52 is known to inhibit cell proliferation; however, the detailed mechanism remains poorly understood. In this study, we found that FKBP52 depletion decreased transcription, leading to stabilization of p53, and suppressed cell proliferation. We identified NFATc1 and NFATc3 as transcription factors that regulate We also found that FKBP52 associated with NFATc3 and facilitated its nuclear translocation. In addition, calcineurin, a well-known Ca phosphatase essential for activation of NFAT, plays a role in transcription. Supporting this notion, expression was found to be regulated by intracellular Ca Taken together, these findings reveal a new role of FKBP52 in promoting cell proliferation via the NFAT-MDM2-p53 axis, and indicate that inhibition of FKBP52 could be a new therapeutic tool to activate p53 and inhibit cell proliferation.
Topics: Humans; Tumor Suppressor Protein p53; Tacrolimus Binding Proteins; Cell Proliferation; NFATC Transcription Factors; Proto-Oncogene Proteins c-mdm2; Cell Line, Tumor; Calcium; Calcineurin; Gene Expression Regulation, Neoplastic; Neoplasms; Signal Transduction
PubMed: 38803221
DOI: 10.26508/lsa.202302426 -
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi =... May 2024Objective To explore the regulatory role of dual-specificity phosphatase 5 (DUSP5) in BCG-mediated inflammatory response in mouse RAW264.7 macrophages. Methods Western...
Objective To explore the regulatory role of dual-specificity phosphatase 5 (DUSP5) in BCG-mediated inflammatory response in mouse RAW264.7 macrophages. Methods Western blot analysis was employed to detect the expression changes of DUSP5 in BCG-infected RAW264.7 macrophages at the period of 0.5, 1, 2, 4, 6, 8, 12 and 24 hours. Intracellular DUSP5 was reduced by small interfering RNA (siRNA) and transfected RAW264.7 macrophages were divided into siRNA-negative control (si-NC) group, DUSP5 knockdown (si-DUSP5) group, si-NC combined BCG infection group, and si-DUSP5 combined BCG infection group. Real-time quantitative PCR was conducted to measure the mRNA expression of interleukin 1β (IL-1β), IL-6, tumor necrosis factor α (TNF-α), and IL-10 in cells. ELISA was performed to measure the concentration of the cytokines in cell culture medium. Western blot analysis was performed to detect the expression changes of cellular nuclear factor κB (NF-κB) and phosphorylated NF-κB (p-NF-κB). Results BCG infection upregulated DUSP5 protein expression in RAW264.7 macrophages with the expression of DUSP5 reaching the peak after 4 hours' BCG stimulation. Comparing with si-NC combined BCG infection group, DUSP5 knockdown inhibited the expression and secretion of pro-inflammatory factors IL-1β, IL-6, and TNF-α, while the expression of the anti-inflammatory factor IL-10 was not affected by DUSP5. Moreover, knockdown of DUSP5 inhibited the phosphorylation of NF-κB in cells. Conclusion DUSP5 knockdown inhibites BCG-mediated macrophage inflammatory response via blocking NF-κB signaling activation.
Topics: Animals; Mice; RAW 264.7 Cells; Dual-Specificity Phosphatases; NF-kappa B; Signal Transduction; Macrophages; Inflammation; Gene Knockdown Techniques; Mycobacterium bovis; Cytokines
PubMed: 38790096
DOI: No ID Found -
Molecular Cancer Research : MCR May 2024HBV-associated hepatocellular carcinoma (HCC) represents the prevalent form of HCC, with HBx protein being a crucial oncoprotein. Numerous members of the protein...
HBV-associated hepatocellular carcinoma (HCC) represents the prevalent form of HCC, with HBx protein being a crucial oncoprotein. Numerous members of the protein tyrosine phosphatase non-receptor (PTPN) family have been confirmed to be significantly associated with the occurrence and progression of malignant tumors. Our group has previously identified the involvement of PTPN13 in HCC. However, the roles of other PTPNs in HCC still requires further investigation. In this study, we found PTPN18 expression was significantly downregulated within HCC tissues compared to that in adjacent non-tumor tissues and normal liver tissues. Functionally, PTPN18 exerted inhibitory effects on the proliferation, migration, invasion, and sphere-forming capability of HCC cells, while concurrently promoting apoptotic processes. Through phospho-protein microarray screening followed by subsequent validation experiments, we identified that PTPN18 could activate the p53 signaling pathway and suppress the AKT/FOXO1 signaling cascade in HCC cells. Moreover, we found that the HBx protein mediated the repression of PTPN18 expression by upregulating miR-128-3p. Collectively, our study unveiled the role of PTPN18 as a tumor suppressor in HBV-related HCC. Implications: Our findings revealed PTPN18 might serve as a potential diagnostic and therapeutic target for HBV-related HCC.
PubMed: 38787319
DOI: 10.1158/1541-7786.MCR-23-0696