Cyclophilin A is a mitochondrial factor that forms complexes with p23 - correlative evidence for an anti-apoptotic action

p23 protects against ferroptosis of brain microvascular endothelial cells in ischemic stroke

Ferroptosis is a type of iron‑dependent regulated cell death that differs from apoptosis, autophagy or necrosis. p23 serves as a co‑chaperone and performs a unique biological function in various diseases by binding to client proteins to modulate their biological functions; however, its effect on ferroptosis remains largely unknown. In the present study, the effects of cerebral ischemia/reperfusion (I/R) injury (CIRI) or oxygen‑glucose deprivation/reoxygenation on the blood‑brain barrier (BBB) and ferroptosis in brain microvascular endothelial cells (BMECs), as well as the expression of p23, were examined. Subsequently, the effects of p23 on CIRI‑induced BBB dysfunction and BMEC ferroptosis were determined. Finally, the role of glutathione peroxidase 4 (GPX4) in the regulatory effects of p23 on ferroptosis was detected. The results revealed that p23 protected against BBB injury caused by CIRI by inhibiting ferroptosis in BMECs. The effect of p23 on ferroptosis was then explored, and it was found that the expression of GPX4, a major regulator of ferroptosis, was promoted by p23. Furthermore, molecular docking and co‑immunoprecipitation experiments revealed that p23 could bind to GPX4 through its N‑terminal domain (1‑90aa), enhance the stability of GPX4 and inhibit the degradation of GPX4 by cycloheximide. Finally, a cerebral I/R animal model was established using GPX4 conditional knockout mice (GPX4 FosCreERT2/+), and it was revealed that the protective effect of p23 overexpression on the BBB in GPX4 FosCreERT2/+ mice was attenuated compared with that in GPX4 FosCreERT2/‑ mice. In conclusion, p23 may serve a protective role against cerebral I/R‑induced BBB injury by inhibiting ferroptosis in BMECs through enhancing the stability of GPX4, providing a potential therapeutic target for ischemic stroke.

TNF-α disrupts the malate-aspartate shuttle, driving metabolic rewiring in iPSC-derived enteric neural lineages from Parkinson's Disease patients

Gastrointestinal (GI) dysfunction emerges years before motor symptoms in Parkinson's disease (PD), implicating the enteric nervous system (ENS) in early disease progression. However, the mechanisms linking the PD hallmark protein, α-synuclein (α-syn), to ENS dysfunction - and whether these mechanisms are influenced by inflammation - remains elusive. Using iPSC-derived enteric neural lineages from patients with α-syn triplications, we reveal that TNF-α increases mitochondrial-α-syn interactions, disrupts the malate-aspartate shuttle, and forces a metabolic shift toward glutamine oxidation. These alterations drive mitochondrial dysfunction, characterizing metabolic impairment under cytokine stress. Interestingly, targeting glutamate metabolism with Chicago Sky Blue 6B restores mitochondrial function, reversing TNF-α-driven metabolic disruption. Our findings position the ENS as a central player in PD pathogenesis, establishing a direct link between cytokines, α-syn accumulation, metabolic stress and mitochondrial dysfunction. By uncovering a previously unrecognized metabolic vulnerability in the ENS, we highlight its potential as a therapeutic target for early PD intervention.

Memory T Cells: Investigation of Original Models with Transgenic T Cell Receptors

This review summarizes the research data on original mouse models developed in the laboratory of regulatory mechanisms in immunity of the Research Institute of Carcinogenesis, N. N. Blokhin National Medical Research Center of Oncology, Ministry of Health of the Russian Federation. Transfer of the genes of individual α- and β-chains of T cell receptors (TCRs) of memory cells has resulted in production of transgenic animal lines valuable for studying T lymphocyte homeostasis and patterns of formation of their activation profile markers. Investigation of the transgenic models revealed new features of immune selection and tumor progression. In particular, the fundamental property of some TCRs, termed "chain-centricity", has been confirmed; it involves dominance of one of the TCR chains during recognition of the MHC (major histocompatibility complex)/peptide complex. This property makes it possible to artificially generate a significant pool of immunocompetent T cells so it could be used in adoptive immunotherapy for oncological and infectious diseases. Transfer of the dominant active TCR α-chains provides the possibility for constructing organisms with innate specific immunological resistance to certain pathogens. The results of recent studies indicate that TCR, determining the T lymphocyte relationship with its MHC microenvironment, has an instructive role in formation of its functions and phenotype. One of these functions may be production of cyclophilin A by the cortisone-resistant memory cells localized in thymus. The evidence has been accumulated that expression of TCR with a certain structure and specificity is a sufficient condition for formation of the functional potential of memory cells in a T cell, regardless of its former interaction with antigenic MHC/peptide complexes.

Cyclophilin A facilitates HIV-1 integration

Cyclophilin A (CypA) binds to the HIV-1 capsid to facilitate reverse transcription and nuclear entry and counter the antiviral activity of TRIM5α. Interestingly, recent studies suggest that the capsid enters the nucleus of an infected cell and uncoats prior to integration. We have previously reported that the capsid protein regulates HIV-1 integration. Therefore, we probed whether CypA-capsid interaction also regulates this post-nuclear entry step. First, we challenged CypA-expressing (CypA+/+) and CypA-depleted (CypA-/-) cells with HIV-1 and quantified the levels of provirus. CypA-depletion significantly reduced integration, an effect that was independent of CypA's effect on reverse transcription, nuclear entry, and the presence or absence of TRIM5α. In addition, cyclosporin A, an inhibitor that disrupts CypA-capsid binding, inhibited proviral integration in CypA+/+ cells but not in CypA-/- cells. HIV-1 capsid mutants (G89V and P90A) deficient in CypA binding were also blocked at the integration step in CypA+/+ cells but not in CypA-/- cells. Then, to understand the mechanism, we assessed the integration activity of the HIV-1 preintegration complexes (PICs) extracted from acutely infected cells. PICs from CypA-/- cells retained lower integration activity in vitro compared to those from CypA+/+ cells. PICs from cells depleted of both CypA and TRIM5α also had lower activity, suggesting that CypA's effect on PIC was independent of TRIM5α. Finally, CypA protein specifically stimulated PIC activity, as this effect was significantly blocked by CsA. Collectively, these results provide strong evidence that CypA directly promotes HIV-1 integration, a previously unknown role of this host factor in the nucleus of an infected cell.

IMPORTANCE

Interaction between the HIV-1 capsid and host cellular factors is essential for infection. However, the molecular details and functional consequences of viral-host factor interactions during HIV-1 infection are not fully understood. Over 30 years ago, Cyclophilin A (CypA) was identified as the first host protein to bind to the HIV-1 capsid. Now it is established that CypA-capsid interaction promotes reverse transcription and nuclear entry of HIV-1. In addition, CypA blocks TRIM5α-mediated restriction of HIV-1. In this report, we show that CypA promotes the post-nuclear entry step of HIV-1 integration by binding to the viral capsid. Notably, we show that CypA stimulates the viral DNA integration activity of the HIV-1 preintegration complex. Collectively, our studies identify a novel role of CypA during the early steps of HIV-1 infection. This new knowledge is important because recent reports suggest that an operationally intact HIV-1 capsid enters the nucleus of an infected cell.

Cyclophilin A Facilitates HIV-1 DNA Integration

Cyclophilin A (CypA) promotes HIV-1 infection by facilitating reverse transcription, nuclear entry and by countering the antiviral activity of TRIM5α. These multifunctional roles of CypA are driven by its binding to the viral capsid. Interestingly, recent studies suggest that the HIV-1 capsid lattice enters the nucleus of an infected cell and uncoats just before integration. Therefore, we tested whether CypA-capsid interaction regulates post-nuclear entry steps of infection, particularly integration. First, we challenged CypA-expressing (CypA +/+ ) and CypA-depleted (CypA -/- ) cells with HIV-1 particles and quantified the resulting levels of provirus. Surprisingly, CypA-depletion significantly reduced integration, an effect that was independent of CypA's effect on reverse transcription, nuclear entry, and the presence or absence of TRIM5α. Additionally, cyclosporin A, an inhibitor that disrupts CypA-capsid binding, inhibited HIV-1 integration in CypA +/+ cells but not in CypA -/- cells. Accordingly, HIV-1 capsid mutants (G89V and P90A) deficient in CypA binding were also blocked at integration in CypA +/+ cells but not in CypA -/- cells. Then, to understand the mechanism, we assessed the integration activity of HIV-1 preintegration complexes (PICs) extracted from infected cells. The PICs from CypA -/- cells had lower activity in vitro compared to those from CypA +/+ cells. PICs from cells depleted for CypA and TRIM5α also had lower activity, suggesting that CypA's effect on PIC activity is independent of TRIM5α. Finally, addition of CypA protein significantly stimulated the integration activity of PICs extracted from both CypA +/+ and CypA -/- cells. Collectively, these results suggest that CypA promotes HIV-1 integration, a previously unknown role of this host factor.

Importance

HIV-1 capsid interaction with host cellular factors is essential for establishing a productive infection. However, the molecular details of such virus-host interactions are not fully understood. Cyclophilin A (CypA) is the first host protein identified to specifically bind to the HIV-1 capsid. Now it is established that CypA promotes reverse transcription and nuclear entry steps of HIV-1 infection. In this report, we show that CypA promotes HIV-1 integration by binding to the viral capsid. Specifically, our results demonstrate that CypA promotes HIV-1 integration by stimulating the activity of the viral preintegration complex and identifies a novel role of CypA during HIV-1 infection. This new knowledge is important because recent reports suggest that an operationally intact HIV-1 capsid enters the nucleus of an infected cell.

Emerging role of cyclophilin A in HIV-1 infection: from producer cell to the target cell nucleus

The HIV-1 genome encodes a small number of proteins with structural, enzymatic, regulatory, and accessory functions. These viral proteins interact with a number of host factors to promote the early and late stages of HIV-1 infection. During the early stages of infection, interactions between the viral proteins and host factors enable HIV-1 to enter the target cell, traverse the cytosol, dock at the nuclear pore, gain access to the nucleus, and integrate into the host genome. Similarly, the viral proteins recruit another set of host factors during the late stages of infection to orchestrate HIV-1 transcription, translation, assembly, and release of progeny virions. Among the host factors implicated in HIV-1 infection, Cyclophilin A (CypA) was identified as the first host factor to be packaged within HIV-1 particles. It is now well established that CypA promotes HIV-1 infection by directly binding to the viral capsid. Mechanistic models to pinpoint CypA's role have spanned from an effect in the producer cell to the early steps of infection in the target cell. In this review, we will describe our understanding of the role(s) of CypA in HIV-1 infection, highlight the current knowledge gaps, and discuss the potential role of this host factor in the post-nuclear entry steps of HIV-1 infection.

Testosterone upregulates glial cell line-derived neurotrophic factor (GDNF) and promotes neuroinflammation to enhance glioma cell survival and proliferation

BACKGROUND

Testosterone contributes to male organism development, such as bone density, muscle development, and fat repartition. Estrogen (derived from testosterone) also contributes to female reproductive system development. Here, we investigated the effect of testosterone on glioma cells and brain neuron inflammation essential for cancer development and progression.

METHODS

The human astrocyte and glioma cell lines were treated with 6 ng/ml exogenous testosterone in vitro. We performed cell counting kit-8, transwell, and wound healing assays to determine the effect of testosterone on glioma cell proliferation, migration, and invasion. The glioma cells were injected into the xenograft and treated with 5 µl concentrated testosterone. Transcriptional suppression of glial cell line-derived neurotrophic factor (GDNF) was performed to evaluate brain neuron inflammation and survival. The tumor tissues were assessed by hematoxylin-eosin staining and immunohistochemistry.

RESULTS

Testosterone upregulates GDNF to stimulate proliferation, migration, and invasion of glioma cells. Pathologically, the augmentation of GDNF and cyclophilin A contributed to neuroprotection when treated with testosterone. Our investigation showed that testosterone contributes to brain neuron and astrocyte inflammation through the upregulation of nuclear factor erythroid 2-related factor 2 (NRF2), glial fibrillary acid protein (GFAP), and sirtuin 5 (SIRT5), resulting in pro-inflammatory macrophages recruitments into the neural microenvironment. Mechanically, testosterone treatment regulates GDNF translocation from the glioma cells and astrocyte nuclei to the cytoplasm.

CONCLUSION

Testosterone upregulates GDNF in glioma cells and astrocytes essential for microglial proliferation, migration, and invasion. Testosterone contributes to brain tumor growth via GDNF and inflammation. The contribution of testosterone, macrophages, and astrocytes, in old neuron rescue, survival, and proliferation. During brain neuron inflammation, the organism activates and stimulates the neuron rescue through the enrichment of the old neuron microenvironment with growth factors such as GDNF, BDNF, SOX1/2, and MAPK secreted by the surrounding neurons and glial cells to maintain the damaged neuron by inflammation alive even if the axon is dead. The immune response also contributes to brain cell survival through the secretion of proinflammatory cytokines, resulting in inflammation maintenance. The rescued old neuron interaction with infiltrated macrophages contributes to angiogenesis to supplement the old neuron with more nutrients leading to metabolism activation and surrounding cell uncontrollable cell growth.

The emerging importance of immunophilins in fibrosis development

Immunophilins are a family of proteins encompassing FK506-binding proteins (FKBPs) and cyclophilins (Cyps). FKBPs and Cyps exert peptidyl-prolyl cis-trans isomerase (PPIase) activity, which facilitates diverse protein folding assembly, or disassembly. In addition, they bind to immunosuppressant medications where FKBPs bind to tacrolimus (FK506) and rapamycin, whereas cyclophilins bind to cyclosporin. Some large immunophilins have domains other than PPIase referred to as tetratricopeptide (TPR) domain, which is involved in heat shock protein 90 (Hsp90) and heat shock protein 70 (Hsp 70) chaperone interaction. The TPR domain confers immunophilins’ pleotropic actions to mediate various physiological and biochemical processes. So far, immunophilins have been implicated to play an important role in pathophysiology of inflammation, cancer and neurodegenerative disorders. However, their importance in the development of fibrosis has not yet been elucidated. In this review we focus on the pivotal functional and mechanistic roles of different immunophilins in fibrosis establishment affecting various organs. The vast majority of the studies reported that cyclophilin A, FKBP12 and FKBP10 likely induce organ fibrosis through the calcineurin or TGF-β pathways. FKBP51 demonstrated a role in myelofibrosis development through calcineurin-dependant pathway, STAT5 or NF-κB pathways. Inhibition of these specific immunophilins has been shown to decrease the extent of fibrosis suggesting that immunophilins could be a novel promising therapeutic target to prevent or reverse fibrosis.

The adhesion protein of Mycoplasma genitalium inhibits urethral epithelial cell apoptosis through CypA-CD147 activating PI3K/ Akt/NF-κB pathway

By interacting with the receptor on the host cells membrane, Mycoplasma genitalium, a prokaryotic bacterium primarily transmitted through sexual contact, can adhere to and even enter cells. The adhesion protein of M. genitalium (MgPa) plays a critical function in the adhering and subsequent invasion into host cells. Our prior studies verified that cyclophilin A (CypA) was the receptor of MgPa on human urethral epithelial cells (SV-HUC-1) membrane and could induce pro-inflammatory cytokines production through the CypA-CD147-ERK-NF-κB pathway. This research aims to understand how MgPa interacts with its membrane receptor CypA to cause apoptosis in host cells. We employed flow cytometry to see if MgPa prevents or enhances apoptosis of SV-HUC-1 cells. The apoptosis-related proteins such as Bax, caspase-3, and cleaved caspase-3 were assayed using Western blot. Results suggested that MgPa could inhibit the apoptosis of SV-HUC-1 cells. And we demonstrated that interference with the expression of CypA or CD147 significantly reversed the inhibitory effect of MgPa on SV-HUC-1 cells apoptosis, indicating that MgPa inhibited urothelial cells apoptosis through CypA/CD147. Furthermore, we discovered that MgPa regulates the PI3K/Akt/NF-κB pathway through CypA/CD147 to inhibit SV-HUC-1 cells apoptosis. Ultimately, the inhibitory effect of MgPa on the apoptosis of the urothelial epithelial cells extracted from CypA-knockout mice was validated by Annexin V/PI assay. The results corroborated that MgPa could also inhibit mouse urothelial epithelial cells apoptosis. In summary, we demonstrated that MgPa could inhibit SV-HUC-1 cells apoptosis via regulating the PI3K/Akt/NF-κB pathway through CypA/CD147, providing experimental evidence for elucidating the survival strategies of M. genitalium in host cells. KEY POINTS: • M. genitalium protein of adhesion inhibited human urethral epithelial cells apoptosis through CypA-CD147 activating the signal pathway of PI3K/Akt/NF-κB • The knockdown of CypA and CD147 could downregulate the M. genitalium -activated PI3K/Akt/NF-κB pathway in SV-HUC-1 cells • MgPa could inhibit the apoptosis of normal C57BL mouse primary urethral epithelial cells, but not for CypA-knockout C57BL mouse primary urethral epithelial cells.

A necroptosis -related signature for predicting prognosis and immunotherapy in hepatocellular carcinoma

Background: Hepatocellular Carcinoma (HCC) is an aggressive tumor with an inferior prognosis. Necroptosis is a new form of programmed death that plays a dual effect on the tumor. However, the role of necroptosis-related genes(NRGs) in HCC remains unknown.

Methods: All datasets were downloaded from publicly available databases. The consensus clustering analysis was used to classify patients into different subtypes based on NRGs. The Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression were used to develop a prognostic signature. Tumor Immune Dysfunction and Exclusion (TIDE) was used to predict immunotherapy response.

Results: The genetic and transcriptional changes of NRGs were observed in HCC. Patients were classified into three clusters based on differentially expressed NRGs, of which Cluster-3 had the worst prognosis and the highest immune infiltration. The prognostic signature was developed based on 8-NRGs, which have shown excellent prognostic performance. The high-risk group in the signature presented significantly higher immune infiltration, such as aDCs, iDCs, macrophages, and Treg, compared to the low-risk group. TMB and immune checkpoints were also higher in the high-risk group. Moreover, a lower TIDE score was observed in the high-risk group, indicating the patients with high risk-score may be suitable for immunotherapy. Via the dataset of IMvigor210, we found a higher risk score in the immunotherapy response group.

Conclusion: We developed a new necroptosis-related signature for predicting prognosis with the potential to predict immunotherapy for HCC patients.

Mitochondrial-Targeted Therapy for Doxorubicin-Induced Cardiotoxicity

Anthracyclines, such as doxorubicin, are effective chemotherapeutic agents for the treatment of cancer, but their clinical use is associated with severe and potentially life-threatening cardiotoxicity. Despite decades of research, treatment options remain limited. The mitochondria is commonly considered to be the main target of doxorubicin and mitochondrial dysfunction is the hallmark of doxorubicin-induced cardiotoxicity. Here, we review the pathogenic mechanisms of doxorubicin-induced cardiotoxicity and present an update on cardioprotective strategies for this disorder. Specifically, we focus on strategies that can protect the mitochondria and cover different therapeutic modalities encompassing small molecules, post-transcriptional regulators, and mitochondrial transfer. We also discuss the shortcomings of existing models of doxorubicin-induced cardiotoxicity and explore advances in the use of human pluripotent stem cell derived cardiomyocytes as a platform to facilitate the identification of novel treatments against this disorder.

Ivabradine Induces Cardiac Protection against Myocardial Infarction by Preventing Cyclophilin-A Secretion in Pigs under Coronary Ischemia/Reperfusion

In response to cardiac ischemia/reperfusion, proteolysis mediated by extracellular matrix metalloproteinase inducer (EMMPRIN) and its secreted ligand cyclophilin-A (CyPA) significantly contributes to cardiac injury and necrosis. Here, we aimed to investigate if, in addition to the effect on the funny current (I(f)), Ivabradine may also play a role against cardiac necrosis by reducing EMMPRIN/CyPA-mediated cardiac inflammation. In a porcine model of cardiac ischemia/reperfusion (IR), we found that administration of 0.3 mg/kg Ivabradine significantly improved cardiac function and reduced cardiac necrosis by day 7 after IR, detecting a significant increase in cardiac CyPA in the necrotic compared to the risk areas, which was inversely correlated with the levels of circulating CyPA detected in plasma samples from the same subjects. In testing whether Ivabradine may regulate the levels of CyPA, no changes in tissue CyPA were found in healthy pigs treated with 0.3 mg/kg Ivabradine, but interestingly, when analyzing the complex EMMPRIN/CyPA, rather high glycosylated EMMPRIN, which is required for EMMPRIN-mediated matrix metalloproteinase (MMP) activation and increased CyPA bonding to low-glycosylated forms of EMMPRIN were detected by day 7 after IR in pigs treated with Ivabradine. To study the mechanism by which Ivabradine may prevent secretion of CyPA, we first found that Ivabradine was time-dependent in inhibiting co-localization of CyPA with the granule exocytosis marker vesicle-associated membrane protein 1 (VAMP1). However, Ivabradine had no effect on mRNA expression nor in the proteasome and lysosome degradation of CyPA. In conclusion, our results point toward CyPA, its ligand EMMPRIN, and the complex CyPA/EMMPRIN as important targets of Ivabradine in cardiac protection against IR.