African-centric TP53 variant increases iron accumulation and bacterial pathogenesis but improves response to malaria toxin

Hub genes, a diagnostic model, and immune infiltration based on ferroptosis-linked genes in schizophrenia

Background

Schizophrenia (SCZ) is a prevalent and serious mental disorder, and the exact pathophysiology of this condition is not fully understood. In previous studies, it has been proven that ferroprotein levels are high in SCZ. It has also been shown that this inflammatory response may modify fibromodulin. Accumulating evidence indicates a strong link between metabolism and ferroptosis. Therefore, the present study aims to identify ferroptosis-linked hub genes to further investigate the role that ferroptosis plays in the development of SCZ.

Material and methods

From the GEO database, four microarray data sets on SCZ (GSE53987, GSE38481, GSE18312, and GSE38484) and ferroptosis-linked genes were extracted. Using the prefrontal cortex expression matrix of SCZ patients and healthy individuals as the control group from GSE53987, weighted gene co-expression network analysis (WGCNA) was performed to discover SCZ-linked module genes. From the feed, genes associated with ferroptosis were retrieved. The intersection of the module and ferroptosis-linked genes was done to obtain the hub genes. Then, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and Gene Set Enrichment Analysis (GSEA) were conducted. The SCZ diagnostic model was established using logistic regression, and the GSE38481, GSE18312, and GSE38484 data sets were used to validate the model. Finally, hub genes linked to immune infiltration were examined.

Results

A total of 13 SCZ module genes and 7 hub genes linked to ferroptosis were obtained: DECR1, GJA1, EFN2L2, PSAT1, SLC7A11, SOX2, and YAP1. The GO/KEGG/GSEA study indicated that these hub genes were predominantly enriched in mitochondria and lipid metabolism, oxidative stress, immunological inflammation, ferroptosis, Hippo signaling pathway, AMP-activated protein kinase pathway, and other associated biological processes. The diagnostic model created using these hub genes was further confirmed using the data sets of three blood samples from patients with SCZ. The immune infiltration data showed that immune cell dysfunction enhanced ferroptosis and triggered SCZ.

Conclusion

In this study, seven critical genes that are strongly associated with ferroptosis in patients with SCZ were discovered, a valid clinical diagnostic model was built, and a novel therapeutic target for the treatment of SCZ was identified by the investigation of immune infiltration.

Molecular mechanisms of mitochondria-mediated ferroptosis: a potential target for antimalarial interventions

Ferroptosis is an iron-dependent form of regulated cell death characterized by glutathione (GSH) depletion, glutathione peroxidase 4 (GPX4) inactivation, and the build-up of lipotoxic reactive species. Ferroptosis-targeted induction is a promising therapeutic approach for addressing antimalarial drug resistance. In addition to being the primary source of intracellular energy supply and reactive oxygen species (ROS) generation, mitochondria actively participate in diverse forms of regulated cell death, including ferroptosis. Altered mitochondrial morphology and functionality are attributed to ferroptosis. Diverse mitochondria-related proteins and metabolic activities have been implicated in fine-tuning the action of ferroptosis inducers. Herein, we review recent progress in this evolving field, elucidating the numerous mechanisms by which mitochondria regulate ferroptosis and giving an insight into the role of the organelle in ferroptosis. Additionally, we present an overview of how mitochondria contribute to ferroptosis in malaria. Furthermore, we attempt to shed light on an inclusive perspective on how targeting malaria parasites' mitochondrion and attacking redox homeostasis is anticipated to induce ferroptosis-mediated antiparasitic effects.

Ferroptosis in immunostimulation and immunosuppression

Ferroptosis is a form of iron-dependent regulated cell death characterized by the accumulation of toxic lipid peroxides, particularly in the plasma membrane, leading to lytic cell death. While it plays a crucial role in maintaining the overall health and proper functioning of multicellular organisms, it can also contribute to tissue damage and pathological conditions. Although ferroptotic damage is generally recognized as an immunostimulatory process associated with the release of damage-associated molecular patterns (DAMPs), the occurrence of ferroptosis in immune cells or the release of immunosuppressive molecules can result in immune tolerance. Consequently, there is ongoing exploration of targeting the upstream signals or the machinery of ferroptosis to therapeutically enhance or inhibit the immune response. In addition to introducing the core molecular mechanisms of ferroptosis, we will focus on the immune characteristics of ferroptosis in pathological conditions, particularly in the context of infection, sterile inflammation, and tumor immunity.

Emerging insights into ethnic-specific TP53 germline variants

The recent expansion of human genomics repositories has facilitated the discovery of novel TP53 variants in populations of different ethnic origins. Interpreting TP53 variants is a major clinical challenge because they are functionally diverse, confer highly variable predisposition to cancer (including elusive low-penetrance alleles), and interact with genetic modifiers that alter tumor susceptibility. Here, we discuss how a cancer risk continuum may relate to germline TP53 mutations on the basis of our current review of genotype-phenotype studies and an integrative analysis combining functional and sequencing datasets. Our study reveals that each ancestry contains a distinct TP53 variant landscape defined by enriched ethnic-specific alleles. In particular, the discovery and characterization of suspected low-penetrance ethnic-specific variants with unique functional consequences, including P47S (African), G334R (Ashkenazi Jewish), and rs78378222 (Icelandic), may provide new insights in terms of managing cancer risk and the efficacy of therapy. Additionally, our analysis highlights infrequent variants linked to milder cancer phenotypes in various published reports that may be underdiagnosed and require further investigation, including D49H in East Asians and R181H in Europeans. Overall, the sequencing and projected functions of TP53 variants arising within ethnic populations and their interplay with modifiers, as well as the emergence of CRISPR screens and AI tools, are now rapidly improving our understanding of the cancer susceptibility spectrum, leading toward more accurate and personalized cancer risk assessments.

Environmental Determinants of Ferroptosis in Cancer

Given the enormous suffering and death associated with human cancers, there is an urgent need for novel therapeutic approaches to target tumor growth and metastasis. While initial efforts have focused on the dysregulated oncogenic program of cancer cells, recent focus has been on the modulation and targeting of many "cancer-friendly," non-genetic tumor microenvironmental factors, which support and enable tumor progression and metastasis. Two prominent examples are anti-angiogenesis and immunotherapy that target tumor-supporting vascularization and the immune-suppressive tumor microenvironment (TME), respectively. Lately, there has been significant interest in the therapeutic potential of ferroptosis, a natural tumor suppression mechanism that normally occurs as a result of oxidative stress, iron imbalance, and accumulation of lipid peroxides. While numerous studies have identified various cell intrinsic mechanisms to protect or promote ferroptosis, the role of various TME stress factors are also recently recognized to modulate the tumor cells' susceptibility to ferroptosis. This review aims to compile and highlight evidence of these factors, how various TME stresses affect ferroptosis, and their implications in various stages of tumor development and expected response to ferroptosis-triggering therapeutics under development. Consequently, understanding ways to enhance ferroptosis sensitivity both intracellularly and in the TME may optimize therapeutic sensitivity to minimize or prevent tumor growth and metastasis.

Neither the African-Centric S47 Nor P72 Variant of TP53 Is Associated With Reduced Risk of Febrile Malaria in a Malian Cohort Study

BACKGROUND

TP53 has been shown to play a role in inflammatory processes, including malaria. We previously found that p53 attenuates parasite-induced inflammation and predicts clinical protection to Plasmodium falciparum infection in Malian children. Here, we investigated whether p53 codon 47 and 72 polymorphisms are associated with differential risk of P. falciparum infection and uncomplicated malaria in a prospective cohort study of malaria immunity.

METHODS

p53 codon 47 and 72 polymorphisms were determined by sequencing TP53 exon 4 in 631 Malian children and adults enrolled in the Kalifabougou cohort study. The effects of these polymorphisms on the prospective risk of febrile malaria, incident parasitemia, and time to fever after incident parasitemia over 6 months of intense malaria transmission were assessed using Cox proportional hazards models.

RESULTS

Confounders of malaria risk, including age and hemoglobin S or C, were similar between individuals with or without p53 S47 and R72 polymorphisms. Relative to their respective common variants, neither S47 nor R72 was associated with differences in prospective risk of febrile malaria, incident parasitemia, or febrile malaria after parasitemia.

CONCLUSIONS

These findings indicate that p53 codon 47 and 72 polymorphisms are not associated with protection against incident P. falciparum parasitemia or uncomplicated febrile malaria.

The African-centric P47S Variant of TP53 Confers Immune Dysregulation and Impaired Response to Immune Checkpoint Inhibition

The tumor suppressor TP53 is the most frequently mutated gene in cancer and is mutationally inactivated in 50% of sporadic tumors. Inactivating mutations in TP53 also occur in Li Fraumeni syndrome (LFS). In addition to germline mutations in TP53 in LFS that completely inactivate this protein, there are many more germline mutant forms of TP53 in human populations that partially inactivate this protein: we call these partially inactivating mutations "hypomorphs." One of these hypomorphs is a SNP that exists in 6%-10% of Africans and 1%-2% of African Americans, which changes proline at amino acid 47 to serine (Pro47Ser; P47S). We previously showed that the P47S variant of p53 is intrinsically impaired for tumor suppressor function, and that this SNP is associated with increased cancer risk in mice and humans. Here we show that this SNP also influences the tumor microenvironment, and the immune microenvironment profile in P47S mice is more protumorigenic. At basal levels, P47S mice show impaired memory T-cell formation and function, along with increased anti-inflammatory (so-called "M2") macrophages. We show that in tumor-bearing P47S mice, there is an increase in immunosuppressive myeloid-derived suppressor cells and decreased numbers of activated dendritic cells, macrophages, and B cells, along with evidence for increased T-cell exhaustion in the tumor microenvironment. Finally, we show that P47S mice demonstrate an incomplete response to anti-PD-L1 therapy. Our combined data suggest that the African-centric P47S variant leads to both intrinsic and extrinsic defects in tumor suppression.

Significance

Findings presented here show that the P47S variant of TP53 influences the immune microenvironment, and the immune response to cancer. This is the first time that a naturally occurring genetic variant of TP53 has been shown to negatively impact the immune microenvironment and the response to immunotherapy.

Emerging insights into the role of ferroptosis in the pathogenesis of autoimmune diseases

Ferroptosis, a novel type of regulated cell death mediated by iron-dependent lipid oxidation, was discovered a decade ago. Significant progress has been made in our knowledge of ferroptosis and immune dysfunction. This review covers recent advancements in the interaction of ferroptosis and the immune system, with an emphasis on autoimmune diseases. The critical regulators of ferroptosis are summarized in the context of reactive oxygen species biology, lipid metabolism, and iron homeostasis. The molecular crosstalk between ferroptosis and different immune cells is also highlighted. Future research is expected to yield new insights into the mechanisms governing ferroptosis and its potential therapeutic benefits in autoimmune diseases.

Common activities and predictive gene signature identified for genetic hypomorphs of TP53

Missense mutations that inactivate p53 occur commonly in cancer, and germline mutations in TP53 cause Li Fraumeni syndrome, which is associated with early-onset cancer. In addition, there are over two hundred germline missense variants of p53 that remain uncharacterized. In some cases, these germline variants have been shown to encode lesser-functioning, or hypomorphic, p53 protein, and these alleles are associated with increased cancer risk in humans and mouse models. However, most hypomorphic p53 variants remain un- or mis-classified in clinical genetics databases. There thus exists a significant need to better understand the behavior of p53 hypomorphs and to develop a functional assay that can distinguish hypomorphs from wild-type p53 or benign variants. We report the surprising finding that two different African-centric genetic hypomorphs of p53 that occur in distinct functional domains of the protein share common activities. Specifically, the Pro47Ser variant, located in the transactivation domain, and the Tyr107His variant, located in the DNA binding domain, both share increased propensity to misfold into a conformation specific for mutant, misfolded p53. Additionally, cells and tissues containing these hypomorphic variants show increased NF-κB activity. We identify a common gene expression signature from unstressed lymphocyte cell lines that is shared between multiple germline hypomorphic variants of TP53, and which successfully distinguishes wild-type p53 and a benign variant from lesser-functioning hypomorphic p53 variants. Our findings will allow us to better understand the contribution of p53 hypomorphs to disease risk and should help better inform cancer risk in the carriers of p53 variants.

The ferroptosis signature predicts the prognosis and immune microenvironment of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a cancer with a high metastatic rate and poor prognosis. Growing studies suggest that ferroptosis take part in the development of tumours. At the same time, the connection between ferroptosis-related genes (FRGs) and the prognosis of NPC remains unclear. In this study, we explored the dysregulated FRGs between normal control and tumour samples of NPC. Firstly, 14 of 36 differentially expressed FRGs were identified in NPC tissues compared to normal tissues, among which ABCC1, GLS2, CS and HMGCR were associated with poor prognosis for patients. The four ferroptosis genes were used for consensus cluster analysis and two risk-related FRGs (ABCC1 and GLS2) were used in a risk model. The ROC curve revealed the good predictive performance of this risk signature. Multivariate analysis revealed that risk score and intratumoral TILs were independent risk factors linked to prognosis. Additionally, our results suggested that the risk signature was attached to the immune microenvironment. Moreover, the NPC patients with high risk were sensitive to chemotherapeutic drugs including axitinib, docetaxel, embelin, epothilone.B, parthenolide, thapsigargin, tipifarnib, vinorelbine. Finally, the expression of ABCC1 and GLS2 was validated in NPC tissues using immunohistochemistry. Together, these results revealed ferroptosis may be a potential biomarker in NPC and representing a promising future direction in prognosis and therapeutic strategy for the treatment of NPC.

Evaluation of genetic variants in ferroptosis-related genes and house dust mite-induced allergic rhinitis risk

BACKGROUND

Ferroptosis-related genes disrupt iron homeostasis and enhance lipid peroxidation to initiate respiratory system diseases. However, the association between genetic variants in the ferroptosis-related genes with house dust mite (HDM)-induced allergic rhinitis (AR) susceptibility remains unclear.

METHODS

A case-control study, involving 222 cases and 237 healthy controls from a Chinese population, was conducted to evaluate the relationship between single nucleotide polymorphisms (SNPs) in ferroptosis-related genes and HDM-induced AR risk. A gene-based analysis was performed by multi-marker analysis of genomic annotation (MAGMA) to identify candidate associated ferroptosis-related genes. A logistic regression model and joint analysis were used to assess the effect of SNPs on HDM-induced AR susceptibility.

RESULTS

Two independent SNPs (rs2305128 in ENPP2 and rs1868088 in EPAS1) were significantly associated with HDM-induced AR risk (OR = 1.82, 95% CI = 1.19-2.79, P = 5.98 × 10-3, PFDR = 4.88 × 10-2; OR = 2.14, 95% CI = 1.23-3.72, P = 6.95 × 10-3, PFDR = 4.87 × 10-2, respectively). Moreover, combined analysis of these two SNPs revealed that an increased risk of HDM-induced AR was positively associated with an increasing number of risk genotypes (Ptrend = 8.48 × 10-5). The stratification analysis showed that the cumulative effect of two SNPs on HDM-induced AR risk was more pronounced among patients presenting more serious symptoms and harboring one or two risk genotypes.

CONCLUSIONS

These findings suggest that the genetic variants in ferroptosis-related genes ENPP2 and EPAS1 may increase HDM-induced AR risk and serve as potential predictors of HDM-induced AR susceptibility.

PLTP is a p53 target gene with roles in cancer growth suppression and ferroptosis

The tumor suppressor protein p53 suppresses cancer by regulating processes such as apoptosis, cell cycle arrest, senescence, and ferroptosis, which is an iron-mediated and lipid peroxide-induced cell death pathway. Whereas numerous p53 target genes have been identified, only a few appear to be critical for the suppression of tumor growth. Additionally, while ferroptosis is clearly implicated in tumor suppression by p53, few p53 target genes with roles in ferroptosis have been identified. We have previously studied germline missense p53 variants that are hypomorphic or display reduced activity. These hypomorphic variants are associated with increased risk for cancer, but they retain the majority of p53 transcriptional function; as such, study of the transcriptional targets of these hypomorphs has the potential to reveal the identity of other genes important for p53-mediated tumor suppression. Here, using RNA-seq in lymphoblastoid cell lines, we identify PLTP (phospholipid transfer protein) as a p53 target gene that shows impaired transactivation by three different cancer-associated p53 hypomorphs: P47S (Pro47Ser, rs1800371), Y107H (Tyr107His, rs368771578), and G334R (Gly334Arg, rs78378222). We show that enforced expression of PLTP potently suppresses colony formation in human tumor cell lines. We also demonstrate that PLTP regulates the sensitivity of cells to ferroptosis. Taken together, our findings reveal PLTP to be a p53 target gene that is extremely sensitive to p53 transcriptional function and which has roles in growth suppression and ferroptosis.

The complexity of p53-mediated metabolic regulation in tumor suppression

Although the classic activities of p53 including induction of cell-cycle arrest, senescence, and apoptosis are well accepted as critical barriers to cancer development, accumulating evidence suggests that loss of these classic activities is not sufficient to abrogate the tumor suppression activity of p53. Numerous studies suggest that metabolic regulation contributes to tumor suppression, but the mechanisms by which it does so are not completely understood. Cancer cells rewire cellular metabolism to meet the energetic and substrate demands of tumor development. It is well established that p53 suppresses glycolysis and promotes mitochondrial oxidative phosphorylation through a number of downstream targets against the Warburg effect. The role of p53-mediated metabolic regulation in tumor suppression is complexed by its function to promote both cell survival and cell death under different physiological settings. Indeed, p53 can regulate both pro-oxidant and antioxidant target genes for complete opposite effects. In this review, we will summarize the roles of p53 in the regulation of glucose, lipid, amino acid, nucleotide, iron metabolism, and ROS production. We will highlight the mechanisms underlying p53-mediated ferroptosis, AKT/mTOR signaling as well as autophagy and discuss the complexity of p53-metabolic regulation in tumor development.

Ferroptosis turns 10: Emerging mechanisms, physiological functions, and therapeutic applications

Ferroptosis, a form of cell death driven by iron-dependent lipid peroxidation, was identified as a distinct phenomenon and named a decade ago. Ferroptosis has been implicated in a broad set of biological contexts, from development to aging, immunity, and cancer. This review describes key regulators of this form of cell death within a framework of metabolism, ROS biology, and iron biology. Key concepts and major unanswered questions in the ferroptosis field are highlighted. The next decade promises to yield further breakthroughs in the mechanisms governing ferroptosis and additional ways of harnessing ferroptosis for therapeutic benefit.

The Role of Ferroptosis in Adverse Left Ventricular Remodeling Following Acute Myocardial Infarction

Ferroptosis is an iron-dependent form of regulated cell death and is distinct from other conventional forms of regulated cell death. It is often characterized by the dysfunction of the antioxidant selenoprotein glutathione peroxidase 4 (GPX4) antioxidant system. This loss of antioxidant capacity leads to the peroxidation of lipids and subsequent compromised plasma membrane structure. Disruption of the GPX4 antioxidant system has been associated with various conditions such as cardiomyopathy and ischemia-reperfusion (I/R) injury. GPX4 regulates lipid peroxidation, and chemical or genetic inhibition of GPX4 leads to reduced cardiac function. Iron chelators or antioxidants can be used for inhibiting ferroptosis, which restores functionality in in vivo and ex vivo experiments and confers overall cardioprotective effects against I/R injury. Moreover, suppression of ferroptosis also suppresses inflammation and limits the extent of left ventricle remodeling after I/R injury. Future research is necessary to understand the role of ferroptosis following an ischemic incident and can lead to the discovery of more potential therapeutics that prevent ferroptosis in the heart.

p53 in ferroptosis regulation: the new weapon for the old guardian

Although the conventional activities of p53 such as cell cycle arrest, senescence, and apoptosis are well accepted as the major checkpoints in stress responses, accumulating evidence implicates the importance of other tumor suppression mechanisms. Among these unconventional activities, an iron-dependent form of non-apoptotic cell death, termed ferroptosis, attracts great interest. Unlike apoptotic cell death, activation of p53 alone is not sufficient to induce ferroptosis directly; instead, through its metabolic targets, p53 is able to modulate the ferroptosis response in the presence of ferroptosis inducers such as GPX4 inhibitors or high levels of ROS. Here, we review the role of ferroptosis in p53-mediated tumor suppression, with a focus on what cellular factors are critical for p53-dependent ferroptosis during tumor suppression and how p53 modulates both the canonical (GPX4-dependent) and the non-canonical (GPX4-independent) ferroptosis pathways. We also discuss the possibility of targeting p53-mediated ferroptotic responses for the treatment of human cancers and potentially, other diseases.

Local ancestry prediction with PyLAE

Summary

We developed PyLAE, a new tool for determining local ancestry along a genome using whole-genome sequencing data or high-density genotyping experiments. PyLAE can process an arbitrarily large number of ancestral populations (with or without an informative prior). Since PyLAE does not involve estimating many parameters, it can process thousands of genomes within a day. PyLAE can run on phased or unphased genomic data. We have shown how PyLAE can be applied to the identification of differentially enriched pathways between populations. The local ancestry approach results in higher enrichment scores compared to whole-genome approaches. We benchmarked PyLAE using the 1000 Genomes dataset, comparing the aggregated predictions with the global admixture results and the current gold standard program RFMix. Computational efficiency, minimal requirements for data pre-processing, straightforward presentation of results, and ease of installation make PyLAE a valuable tool to study admixed populations.

Availability and implementation

The source code and installation manual are available at https://github.com/smetam/pylae.

Shifting the paradigms for tumor suppression: lessons from the p53 field

The TP53 gene continues to hold distinction as the most frequently mutated gene in cancer. Since its discovery in 1979, hundreds of research groups have devoted their efforts toward understanding why this gene is so frequently selected against by tumors, with the hopes of harnessing this information toward improved therapy of cancer. The result is that this protein has been meticulously analyzed in tumor and normal cells, resulting in over one hundred thousand publications, with an average of five thousand papers published on p53 every year for the past decade. The journey toward understanding p53 function has been anything but straightforward; in fact, the field is notable for the numerous times that established paradigms not only have been shifted, but in fact have been shattered or reversed. In this review, we will discuss the manuscripts, or series of manuscripts, that have most radically changed our thinking about how this tumor suppressor functions, and we will delve into the emerging challenges for the future in this important area of research. It is hoped that this review will serve as a useful historical reference for those interested in p53, and a useful lesson on the need to be flexible in the face of established paradigms.

Ferroptosis in infection, inflammation, and immunity

Ferroptosis is a type of regulated necrosis that is triggered by a combination of iron toxicity, lipid peroxidation, and plasma membrane damage. The upstream inducers of ferroptosis can be divided into two categories (biological versus chemical) and activate two major pathways (the extrinsic/transporter versus the intrinsic/enzymatic pathways). Excessive or deficient ferroptotic cell death is implicated in a growing list of physiological and pathophysiological processes, coupled to a dysregulated immune response. This review focuses on new discoveries related to how ferroptotic cells and their spilled contents shape innate and adaptive immunity in health and disease. Understanding the immunological characteristics and activity of ferroptotic death not only illuminates an intersection between cell death and immunity but may also lead to the development of novel treatment approaches for immunopathological diseases.

Unraveling Cell Death Pathways during Malaria Infection: What Do We Know So Far?

Malaria is a parasitic disease (caused by different Plasmodium species) that affects millions of people worldwide. The lack of effective malaria drugs and a vaccine contributes to this disease, continuing to cause major public health and socioeconomic problems, especially in low-income countries. Cell death is implicated in malaria immune responses by eliminating infected cells, but it can also provoke an intense inflammatory response and lead to severe malaria outcomes. The study of the pathophysiological role of cell death in malaria in mammalians is key to understanding the parasite-host interactions and design prophylactic and therapeutic strategies for malaria. In this work, we review malaria-triggered cell death pathways (apoptosis, autophagy, necrosis, pyroptosis, NETosis, and ferroptosis) and we discuss their potential role in the development of new approaches for human malaria therapies.

Effect of the p53 P72R Polymorphism on Mutant TP53 Allele Selection in Human Cancer

BACKGROUND

TP53 mutations occur in more than 50% of cancers. We sought to determine the effect of the intragenic P72R SNP (rs1042522) on the oncogenic properties of mutant p53.

METHODS

P72R allelic selection in tumors was determined from genotype calls and a Gaussian distributed mixture model. The SNP effect on mutant p53 was determined in p53-negative cancer cell lines. RNA-sequencing, chromatin immunoprecipitation, and survival analysis were performed to describe the SNP effect. All statistical tests were 2-sided.

RESULTS

Among 409 patients with germline heterozygous P72R SNP who harbored somatic mutations in TP53, we observed a selection bias against missense TP53 mutants encoding the P72 SNP (P = 1.64 x 10-13). Exogenously expressed hotspot p53 mutants with the P72 SNP were negatively selected in cancer cells. Gene expression analyses showed the enrichment of p53 pathway genes and inflammatory genes in cancer cells transduced with mutants encoding P72 SNP. Immune gene signature is enriched in patients harboring missense TP53 mutations with homozygous P72 SNP. These patients have improved overall survival as compared to those with the R72 SNP (P = 0.04).

CONCLUSION

This is the largest study demonstrating a selection against the P72 SNP.  Missense p53 mutants with the P72 SNP retain partial wild type tumor-suppressive functions, which may explain the selection bias against P72 SNP across cancer types. Ovarian cancer patients with the P72 SNP have a better prognosis than with the R72 SNP. Our study describes a previously unknown role through which the rs1042522 SNP modifies tumor suppressor activities of mutant p53 in patients.

Ferroptosis: molecular mechanisms and health implications

Cell death can be executed through different subroutines. Since the description of ferroptosis as an iron-dependent form of non-apoptotic cell death in 2012, there has been mounting interest in the process and function of ferroptosis. Ferroptosis can occur through two major pathways, the extrinsic or transporter-dependent pathway and the intrinsic or enzyme-regulated pathway. Ferroptosis is caused by a redox imbalance between the production of oxidants and antioxidants, which is driven by the abnormal expression and activity of multiple redox-active enzymes that produce or detoxify free radicals and lipid oxidation products. Accordingly, ferroptosis is precisely regulated at multiple levels, including epigenetic, transcriptional, posttranscriptional and posttranslational layers. The transcription factor NFE2L2 plays a central role in upregulating anti-ferroptotic defense, whereas selective autophagy may promote ferroptotic death. Here, we review current knowledge on the integrated molecular machinery of ferroptosis and describe how dysregulated ferroptosis is involved in cancer, neurodegeneration, tissue injury, inflammation, and infection.

Ubiquitin-specific protease 7 promotes ferroptosis via activation of the p53/TfR1 pathway in the rat hearts after ischemia/reperfusion

Iron overload triggers the ferroptosis in the heart following ischemia/reperfusion (I/R) and transferrin receptor 1 (TfR1) charges the cellular iron uptake. Bioinformatics analysis shows that the three molecules of ubiquitin-specific protease 7 (USP7), p53 and TfR1 form a unique pathway of USP7/p53/TfR1. This study aims to explore whether USP7/p53/TfR1 pathway promotes ferroptosis in rat hearts suffered I/R and the underlying mechanisms. The SD rat hearts were subjected to 1 h-ischemia plus 3 h-reperfusion, showing myocardial injury (increase in creatine kinase release, infarct size, myocardial fiber loss and disarray) and up-regulation of USP7, p53 and TfR1 concomitant with an increase of ferroptosis (reflecting by accumulation of iron and lipid peroxidation while decrease of glutathione peroxidase activity). Inhibition of USP7 activated p53 via suppressing deubiquitination, which led to down-regulation of TfR1, accompanied by the decreased ferroptosis and myocardial I/R injury. Next, H9c2 cells underwent hypoxia/reoxygenation (H/R) in vitro to mimic the myocardial I/R model in vivo. Consistent with the results in vivo, inhibition or knockdown of USP7 reduced the H/R injury (decrease of LDH release and necrosis) and enhanced the ubiquitination of p53 along with the decreased levels of p53 and TfR1 as well as the attenuated ferroptosis (manifesting as the decreased iron content and lipid peroxidation while the increased GPX activity). Knockdown of TfR1 inhibited H/R-induced ferroptosis without p53 deubiquitination. Based on these observations, we conclude that a novel pathway of USP7/p53/TfR1 has been identified in the I/R-treated rat hearts, where up-regulation of USP7promotes ferrptosis via activation of the p53/TfR1 pathway.

Spontaneous and inherited TP53 genetic alterations

The p53 protein is a transcription factor that prevents tumors from developing. In spontaneous and inherited cancers there are many different missense mutations in the DNA binding domain of the TP53 gene that contributes to tumor formation. These mutations produce a wide distribution in the transcriptional capabilities of the mutant p53 proteins with over four logs differences in the efficiencies of forming cancers in many diverse tissue types. These inherited and spontaneous TP53 mutations produce proteins that interact with both genetic and epigenetic cellular modifiers of p53 function and their inherited polymorphisms to produce a large number of diverse phenotypes in individual patients. This manuscript reviews these variables and discusses how the combinations of TP53 genetic alterations interact with genetic polymorphisms, epigenetic alterations, and environmental factors to begin predicting and modifying patient outcomes and provide a better understanding for new therapeutic opportunities.

Increased mTOR activity and metabolic efficiency in mouse and human cells containing the African-centric tumor-predisposing p53 variant Pro47Ser

The Pro47Ser variant of p53 (S47) exists in African-descent populations and is associated with increased cancer risk in humans and mice. Due to impaired repression of the cystine importer Slc7a11, S47 cells show increased glutathione (GSH) accumulation compared to cells with wild -type p53. We show that mice containing the S47 variant display increased mTOR activity and oxidative metabolism, as well as larger size, improved metabolic efficiency, and signs of superior fitness. Mechanistically, we show that mTOR and its positive regulator Rheb display increased association in S47 cells; this is due to an altered redox state of GAPDH in S47 cells that inhibits its ability to bind and sequester Rheb. Compounds that decrease glutathione normalize GAPDH-Rheb complexes and mTOR activity in S47 cells. This study reveals a novel layer of regulation of mTOR by p53, and raises the possibility that this variant may have been selected for in early Africa.

The Regulation of Ferroptosis by Tumor Suppressor p53 and its Pathway

Tumor suppressor p53 plays a key role in tumor suppression. In addition to tumor suppression, p53 is also involved in many other biological and pathological processes, such as immune response, maternal reproduction, tissue ischemia/reperfusion injuries and neurodegenerative diseases. While it has been widely accepted that the role of p53 in regulation of cell cycle arrest, senescence and apoptosis contributes greatly to the function of p53 in tumor suppression, emerging evidence has implicated that p53 also exerts its tumor suppressive function through regulation of many other cellular processes, such as metabolism, anti-oxidant defense and ferroptosis. Ferroptosis is a unique iron-dependent form of programmed cell death driven by lipid peroxidation in cells. Ferroptosis has been reported to be involved in cancer, tissue ischemia/reperfusion injuries and neurodegenerative diseases. Recent studies have shown that ferroptosis can be regulated by p53 and its signaling pathway as well as tumor-associated mutant p53. Interestingly, the regulation of ferroptosis by p53 appears to be highly context-dependent. In this review, we summarize recent advances in the regulation of ferroptosis by p53 and its signaling pathway. Further elucidation of the role and molecular mechanism of p53 in ferroptosis regulation will yield new therapeutic strategies for cancer and other diseases, including neurodegenerative diseases and tissue ischemia/reperfusion injuries.

Hemozoin in Malarial Complications: More Questions Than Answers

Plasmodium parasites contain various virulence factors that modulate the host immune response. Malarial pigment, or hemozoin (Hz), is an undegradable crystalline product of the hemoglobin degradation pathway in the parasite and possesses immunomodulatory properties. An association has been found between Hz accumulation and severe malaria, suggesting that the effects of Hz on the host immune response may contribute to the development of malarial complications. Although the immunomodulatory roles of Hz have been widely investigated, many conflicting data exist, likely due to the variability between experimental set-ups and technical limitations of Hz generation and isolation methods. Here, we critically assess the potential immunomodulatory effects of Hz, its role in malarial complications, and its potential effects after parasite clearance.

Functional interplay among thiol-based redox signaling, metabolism, and ferroptosis unveiled by a genetic variant of TP53

The p53 tumor suppressor protein is a transcription factor and master stress response mediator, and it is subject to reduction-oxidation (redox)-dependent regulation. The P47S variant of TP53, which exists primarily in African-descent populations, associates with an elevated abundance of low molecular weight (LMW) thiols, including glutathione (GSH) and coenzyme A (CoA). Here we show that S47 and P47 cells exhibit distinct metabolic profiles, controlled by their different redox states and expression of Activating Transcription Factor-4 (ATF4). We find that S47 cells exhibit decreased catabolic glycolysis but increased use of the pentose phosphate pathway (PPP), and an enhanced abundance of the antioxidant, NADPH. We identify ATF4 as differentially expressed in P47 and S47 cells and show that ATF4 can reverse the redox status and rescue metabolism of S47 cells, as well as increase sensitivity to ferroptosis. This adaptive metabolic switch is rapid, reversible, and accompanied by thiol-mediated changes in the structures and activities of key glycolytic signaling pathway proteins, including GAPDH and G6PD. The results presented here unveil the important functional interplay among pathways regulating thiol-redox status, metabolic adaptation, and cellular responses to oxidative stress.

The Intersection of DNA Damage Response and Ferroptosis-A Rationale for Combination Therapeutics

Ferroptosis is a novel form of iron-dependent cell death characterized by lipid peroxidation. While the importance and disease relevance of ferroptosis are gaining recognition, much remains unknown about its interaction with other biological processes and pathways. Recently, several studies have identified intricate and complicated interplay between ferroptosis, ionizing radiation (IR), ATM (ataxia-telangiectasia mutated)/ATR (ATM and Rad3-related), and tumor suppressor p53, which signifies the participation of the DNA damage response (DDR) in iron-related cell death. DDR is an evolutionarily conserved response triggered by various DNA insults to attenuate proliferation, enable DNA repairs, and dispose of cells with damaged DNA to maintain genome integrity. Deficiency in proper DDR in many genetic disorders or tumors also highlights the importance of this pathway. In this review, we will focus on the biological crosstalk between DDR and ferroptosis, which is mediated mostly via noncanonical mechanisms. For clinical applications, we also discuss the potential of combining ionizing radiation and ferroptosis-inducers for synergistic effects. At last, various ATM/ATR inhibitors under clinical development may protect ferroptosis and treat many ferroptosis-related diseases to prevent cell death, delay disease progression, and improve clinical outcomes.