A self-amplifying loop of TP53INP1 and P53 drives oxidative stress-induced apoptosis of bone marrow mesenchymal stem cells.

Bone marrow mesenchymal stem cell (BMSC) transplantation is a promising regenerative therapy; however, the survival rate of BMSCs after transplantation is low. Oxidative stress is one of the main reasons for the high apoptosis rate of BMSCs after transplantation, so there is an urgent need to explore the mechanism of oxidative stress-induced apoptosis of BMSCs. Our previous transcriptome sequencing results suggested that the expression of P53-induced nuclear protein 1 (TP53INP1) and the tumor suppressor P53 (P53) was significantly upregulated during the process of oxidative stress-induced apoptosis of BMSCs. The present study further revealed the role and mechanism of TP53INP1 and P53 in oxidative stress-induced apoptosis in BMSCs. Overexpression of TP53INP1 induced apoptosis of BMSCs, knockdown of TP53INP1 alleviated oxidative stress apoptosis of BMSCs. Under oxidative stress conditions, P53 is regulated by TP53INP1, while P53 can positively regulate the expression of TP53INP1, so the two form a positive feedback loop. To clarify the mechanism of feedback loop formation. We found that TP53INP1 inhibited the ubiquitination and degradation of P53 by increasing the phosphorylation level of P53, leading to the accumulation of P53 protein. P53 can act on the promoter of the TP53INP1 gene and increase the expression of TP53INP1 through transcriptional activation. This is the first report on a positive feedback loop formed by TP53INP1 and P53 under oxidative stress. The present study clarified the formation mechanism of the positive feedback loop. The TP53INP1-P53 positive feedback loop may serve as a potential target for inhibiting oxidative stress-induced apoptosis in BMSCs.

p53-Bad* Fusion Gene Therapy Induces Apoptosis In Vitro and Reduces Zebrafish Tumor Burden in Hepatocellular Carcinoma.

With few curative treatments and a global yearly death rate of over 800,000, hepatocellular carcinoma (HCC) desperately needs new therapies. Although wild-type p53 gene therapy has been shown to be safe in HCC patients, it has not shown enough efficacy to merit approval. This work aims to show how p53 can be re-engineered through fusion to the pro-apoptotic BH3 protein Bcl-2 antagonist of cell death (Bad) to improve anti-HCC activity and potentially lead to a novel HCC therapeutic, p53-Bad*. p53-Bad* is a fusion of p53 and Bad, with two mutations, S112A and S136A. We determined mitochondrial localization of p53-Bad* in liver cancer cell lines with varying p53 mutation statuses via fluorescence microscopy. We defined the apoptotic activity of p53-Bad* in four liver cancer cell lines using flow cytometry. To determine the effects of p53-Bad* in vivo, we generated and analyzed transgenic zebrafish expressing hepatocyte-specific p53-Bad*. p53-Bad* localized to the mitochondria regardless of the p53 mutation status and demonstrated superior apoptotic activity over WT p53 in early, middle, and late apoptosis assays. Tumor burden in zebrafish HCC was reduced by p53-Bad* as measured by the liver-to-body mass ratio and histopathology. p53-Bad* induced significant apoptosis in zebrafish HCC as measured by TUNEL staining but did not induce apoptosis in non-HCC fish. p53-Bad* can induce apoptosis in a panel of liver cancer cell lines with varying p53 mutation statuses and induce apoptosis/reduce HCC tumor burden in vivo in zebrafish. p53-Bad* warrants further investigation as a potential new HCC therapeutic.

Generation and Characterization of Site-Specifically Mono-Ubiquitylated p53.

The tumor suppressor p53 is regulated by various posttranslational modifications including different types of ubiquitylation, which exert distinct effects on p53. While modification by ubiquitin chains targets p53 for degradation, attachment of single ubiquitin moieties (mono-ubiquitylation) affects the intracellular location of p53 and/or its interaction with chromatin. However, how this is achieved at the molecular level remains largely unknown. Similarly, since p53 can be ubiquitylated at different lysine residues, it remains unclear if the eventual effect depends on the position of the lysine modified. Here, we combined genetic code expansion with oxime ligation to generate p53 site-specifically mono-ubiquitylated at position 120. We found that mono-ubiquitylation at this position neither interferes with p53 ubiquitylation by the E3 ligases HDM2 and E6AP in complex with the viral E6 oncoprotein nor affects p53 binding to a cognate DNA sequence. Thus, ubiquitylation per se does not affect physiologically relevant properties of p53.

Orotic acid protects pancreatic ß cell by p53 inactivation in diabetic mouse model.

Impairment of pancreatic ß cells is a principal driver of the development of diabetes. Restoring normal insulin release from the ß cells depends on the ATP produced by the intracellular mitochondria. In maintaining mitochondrial function, the tumor suppressor p53 has emerged as a novel regulator of metabolic homeostasis and participates in adaptations to nutritional changes. In this study, we used orotic acid, an intermediate in the pathway for de novo synthesis of the pyrimidine nucleotide, to reduce genotoxicity. Administration of orotic acid reduced p53 activation of MIN6 ß cells and subsequently reduced ß cell death in the db/db mouse. Orotic acid intake helped to maintain the islet size, number of ß cells, and protected insulin secretion in the db/db mouse. In conclusion, orotic acid treatment maintained ß cell function and reduced cell death, and may therefore, be a future therapeutic strategy for the prevention and treatment of diabetes.

Chaperoning the guardian of the genome. The two-faced role of molecular chaperones in p53 tumor suppressor action.

Organized networks of heat shock proteins, which possess molecular chaperone activity, protect cells from abrupt environmental changes. Additionally, molecular chaperones are essential during stress-free periods, where they moderate housekeeping functions. During tumorigenesis, these chaperone networks are extensively remodeled in such a way that they are advantageous to the transforming cell. Molecular chaperones by buffering critical elements of signaling pathways empower tumor evolution leading to chemoresistance of cancer cells. Controversially, the same molecular chaperones, which are indispensable for p53 in reaching its tumor suppressor potential, are beneficial in adopting an oncogenic gain of function phenotype when TP53 is mutated. On the molecular level, heat shock proteins by unwinding the mutant p53 protein expose aggregation-prone sites leading to the sequestration of other tumor suppressor proteins causing inhibition of apoptosis and chemoresistance. Therefore, within this review therapeutic approaches combining classical immuno- and/or chemotherapy with specific inhibition of selected molecular chaperones shall be discussed.

p53-inducible DPYSL4 associates with mitochondrial supercomplexes and regulates energy metabolism in adipocytes and cancer cells.

The tumor suppressor p53 regulates multiple cellular functions, including energy metabolism. Metabolic deregulation is implicated in the pathogenesis of some cancers and in metabolic disorders and may result from the inactivation of p53 functions. Using RNA sequencing and ChIP sequencing of cancer cells and preadipocytes, we demonstrate that p53 modulates several metabolic processes via the transactivation of energy metabolism genes including dihydropyrimidinase-like 4 (DPYSL4). DPYSL4 is a member of the collapsin response mediator protein family, which is involved in cancer invasion and progression. Intriguingly, DPYSL4 overexpression in cancer cells and preadipocytes up-regulated ATP production and oxygen consumption, while DPYSL4 knockdown using siRNA or CRISPR/Cas9 down-regulated energy production. Furthermore, DPYSL4 was associated with mitochondrial supercomplexes, and deletion of its dihydropyrimidinase-like domain abolished its association and its ability to stimulate ATP production and suppress the cancer cell invasion. Mouse-xenograft and lung-metastasis models indicated that DPYSL4 expression compromised tumor growth and metastasis in vivo. Consistently, database analyses demonstrated that low DPYSL4 expression was significantly associated with poor survival of breast and ovarian cancers in accordance with its reduced expression in certain types of cancer tissues. Moreover, immunohistochemical analysis using the adipose tissue of obese patients revealed that DPYSL4 expression was positively correlated with INFg and body mass index in accordance with p53 activation. Together, these results suggest that DPYSL4 plays a key role in the tumor-suppressor function of p53 by regulating oxidative phosphorylation and the cellular energy supply via its association with mitochondrial supercomplexes, possibly linking to the pathophysiology of both cancer and obesity.

Rationale for a Combination Therapy with the STAT5 Inhibitor AC-4-130 and the MCL1 Inhibitor S63845 in the Treatment of FLT3-Mutated or TET2-Mutated Acute Myeloid Leukemia.

The FMS-like tyrosine kinase 3 (FLT3) gene is mutated in one-third of patients with de novo acute myeloid leukemia (AML). Mutated FLT3 variants are constitutively active kinases signaling via AKT kinase, MAP kinases, and STAT5. FLT3 inhibitors have been approved for the treatment of FLT3-mutated AML. However, treatment response to FLT3 inhibitors may be short-lived, and resistance may emerge. Compounds targeting STAT5 may enhance and prolong effects of FLT3 inhibitors in this subset of patients with FLT3-mutated AML. Here STAT5-inhibitor AC-4-130, FLT3 inhibitor midostaurin (PKC412), BMI-1 inhibitor PTC596, MEK-inhibitor trametinib, MCL1-inhibitor S63845, and BCL-2 inhibitor venetoclax were assessed as single agents and in combination for their ability to induce apoptosis and cell death in leukemic cells grown in the absence or presence of bone marrow stroma. Synergistic effects on cell viability were detected in both FLT3-mutated and FLT3-wild-type AML cells treated with AC-4-130 in combination with the MCL1 inhibitor S63845. AML patient samples with a strong response to AC-4-130 and S63845 combination treatment were characterized by mutated FLT3 or mutated TET2 genes. Susceptibility of AML cells to AC-4-130, PTC596, trametinib, PKC412, and venetoclax was altered in the presence of HS-5 stroma. Only the MCL1 inhibitor S63845 induced cell death with equal efficacy in the absence or presence of bone marrow stroma. The combination of the STAT5-inhibitor AC-4-130 and the MCL1 inhibitor S63845 may be an effective treatment targeting FLT3-mutated or TET2-mutated AML.

The role of tumor suppressor p53 in metabolism and energy regulation, and its implication in cancer and lifestyle-related diseases.

The tumor suppressor gene p53 is mutated in approximately more than 50% of human cancers. p53 is also referred to as the "cellular gatekeeper" or "guardian of the genome" because it protects the body from spreading mutated genome induced by various stress. When the cells receives stimuli such as DNA damage, oncogene activation, oxidative stress or undernutrition, p53 gives rise to a number of cellular responses, including cell cycle arrest, apoptosis, cellular senescence and metabolic adaptation. Related to energy metabolisms, it has been reported that p53 reduces glycolysis and enhances mitochondrial respiration. p53 is also involved in the regulation of other cellular metabolism and energy production systems: amino acid metabolism, fatty acid metabolism, nucleic acid metabolism, anti-oxidation, mitochondrial quality control, and autophagy. Moreover, recent studies have shown that p53 gene polymorphisms affect life expectancy and lifestyle-related disease such as type 2 diabetes, suggesting that there is a certain relationship between p53 function and metabolic disorders. In addition, mutant p53 protein does not only lose the tumor suppressor function, but it also gains novel oncogenic function and contributes to tumor development, involving cellular metabolism modification. Therefore, the importance of multifunctionality of p53, particularly with regard to intracellular metabolisms, arouses therapeutic interest and calls attention as the key molecule among cancer, lifestyle-related diseases and life expectancy.

Discovery of Mieap-regulated mitochondrial quality control as a new function of tumor suppressor p53.

The tumor suppressor p53 gene is frequently mutated in human cancers, and the p53 protein suppresses cancer. However, the mechanism behind the p53-mediated tumor suppression is still unclear. Recently, the mitochondria-eating protein (Mieap) was identified as a p53-inducible protein. Mieap induces the accumulation of lysosomal proteins within mitochondria (Mieap-induced accumulation of lysosome-like organelles within mitochondria, or MALM) in response to mitochondrial damage, and eliminates the oxidized mitochondrial proteins to repair unhealthy mitochondria. Furthermore, Mieap also induces vacuole-like structures (Mieap-induced vacuole, or MIV) to eat and degrade unhealthy mitochondria. Therefore, Mieap controls mitochondrial quality by repairing or eliminating unhealthy mitochondria by MALM or MIV, respectively. This mechanism is not mediated by canonical autophagy. Mieap-deficient ApcMin/+ mice show strikingly high rates of intestinal tumor development as well as advanced-grade adenomas and adenocarcinomas. The p53/Mieap/BCL2 interacting protein 3 mitochondrial quality control pathway is frequently inactivated in human colorectal cancers. Defects in Mieap-regulated mitochondrial quality control lead to accumulation of unhealthy mitochondria in cancer cells. Cancer-specific unhealthy mitochondria could contribute to cancer development and aggressiveness through mitochondrial reactive oxygen species and altered metabolism. Mieap-regulated mitochondrial quality control is a newly discovered function of p53 that plays a critical role in tumor suppression.

Cold-water immersion following sprint interval training does not alter endurance signaling pathways or training adaptations in human skeletal muscle.

We investigated the underlying molecular mechanisms by which postexercise cold-water immersion (CWI) may alter key markers of mitochondrial biogenesis following both a single session and 6 wk of sprint interval training (SIT). Nineteen men performed a single SIT session, followed by one of two 15-min recovery conditions: cold-water immersion (10°C) or a passive room temperature control (23°C). Sixteen of these participants also completed 6 wk of SIT, each session followed immediately by their designated recovery condition. Four muscle biopsies were obtained in total, three during the single SIT session (preexercise, postrecovery, and 3 h postrecovery) and one 48 h after the last SIT session. After a single SIT session, phosphorylated (p-)AMPK, p-p38 MAPK, p-p53, and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) mRNA were all increased (P < 0.05). Postexercise CWI had no effect on these responses. Consistent with the lack of a response after a single session, regular postexercise CWI had no effect on PGC-1α or p53 protein content. Six weeks of SIT increased peak aerobic power, maximal oxygen consumption, maximal uncoupled respiration (complexes I and II), and 2-km time trial performance (P < 0.05). However, regular CWI had no effect on changes in these markers, consistent with the lack of response in the markers of mitochondrial biogenesis. Although these observations suggest that CWI is not detrimental to endurance adaptations following 6 wk of SIT, they question whether postexercise CWI is an effective strategy to promote mitochondrial biogenesis and improvements in endurance performance.

Tumor-suppressive p53 Signaling Empowers Metastatic Inhibitor KLF17-dependent Transcription to Overcome Tumorigenesis in Non-small Cell Lung Cancer.

Metastasis, which is controlled by concerted action of multiple genes, is a complex process and is an important cause of cancer death. Krüppel-like factor 17 (KLF17) is a negative regulator of metastasis and epithelial-mesenchymal transition (EMT) during cancer progression. However, the underlying molecular mechanism and biological relevance of KLF17 in cancer cells are poorly understood. Here, we show that tumor suppressor protein p53 plays an integral role to induce KLF17 expression in non-small cell lung cancer (NSCLC). p53 is recruited to the KLF17 promoter and results in the formation of p53-DNA complex. p53 enhances binding of p300 and favors histone acetylation on the KLF17 promoter. Mechanistically, p53 physically interacts with KLF17 and thereby enhances the anti-metastatic function of KLF17. p53 empowers KLF17-mediated EMT genes transcription via enhancing physical association of KLF17 with target gene promoters. Nutlin-3 recruits KLF17 to EMT target gene promoters and results in the formation of KLF17-DNA complex via a p53-dependent pathway. p53 depletion abrogates DNA binding affinity of KLF17 to EMT target gene promoters. KLF17 is critical for p53 cellular activities in NSCLC. Importantly, KLF17 enhances p53 transcription to generate a novel positive feedback loop. KLF17 depletion accelerates lung cancer cell growth in response to chemotherapy. Mechanistically, we found that KLF17 increases the expression of tumor suppressor genes p53, p21, and pRB. Functionally, KLF17 required p53 to suppress cancer cell invasion and migration in NSCLC. In conclusion, our study highlights a novel insight into the anti-EMT effect of KLF17 via a p53-dependent pathway in NSCLC, and KLF17 may be a new therapeutic target in NSCLC with p53 status.

Metabolic activation of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine and DNA adduct formation depends on p53: Studies in Trp53(+/+),Trp53(+/-) and Trp53(-/-) mice.

The expression of the tumor suppressor p53 can influence the bioactivation of, and DNA damage induced by, the environmental carcinogen benzo[a]pyrene, indicating a role for p53 in its cytochrome P450 (CYP)-mediated biotransformation. The carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), which is formed during the cooking of food, is also metabolically activated by CYP enzymes, particularly CYP1A2. We investigated the potential role of p53 in PhIP metabolism in vivo by treating Trp53(+/+), Trp53(+/-) and Trp53(-/-) mice with a single oral dose of 50 mg/kg body weight PhIP. N-(Deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP-C8-dG) levels in DNA, measured by liquid chromatography-tandem mass spectrometry, were significantly lower in liver, colon, forestomach and glandular stomach of Trp53(-/-) mice compared to Trp53(+/+) mice. Lower PhIP-DNA adduct levels in the livers of Trp53(-/-) mice correlated with lower Cyp1a2 enzyme activity (measured by methoxyresorufin-O-demethylase activity) in these animals. Interestingly, PhIP-DNA adduct levels were significantly higher in kidney and bladder of Trp53(-/-) mice compared to Trp53(+/+) mice, which was accompanied by higher sulfotransferase (Sult) 1a1 protein levels and increased Sult1a1 enzyme activity (measured by 2-naphthylsulfate formation from 2-naphthol) in kidneys of these animals. Our study demonstrates a role for p53 in the metabolism of PhIP in vivo, extending previous results on a novel role for p53 in xenobiotic metabolism. Our results also indicate that the impact of p53 on PhIP biotransformation is tissue-dependent and that in addition to Cyp1a enzymes, Sult1a1 can contribute to PhIP-DNA adduct formation.

Highly activated p53 contributes to selectively increased apoptosis of latently HIV-1 infected cells upon treatment of anticancer drugs.

BACKGROUND: Despite the successful inhibition of human immunodeficiency virus type 1 (HIV-1) replication by combination antiretroviral therapy, cells latently infected with HIV-1 remaining in patients are a major obstacle for eradication of HIV-1 infection. The tumor suppressor factor p53 is activated by HIV-1 infection, and restricts HIV-1 replication. However, a therapeutic strategy based on p53 activity has not been considered for elimination of latently infected cells. METHODS: Apoptotic cells were analyzed using flow cytometry with anti-annexin A5-FITC Ab and PI staining upon treatment of anticancer drugs. The expression and activation of p53 and apoptotic molecules in latently HIV-1-infected T cells were compared using Western blot analysis. The role of p53 in the anticancer drug treatment-induced apoptosis of cells latently infected with HIV-1 was determined by knock-down experiment using siRNA against p53. RESULTS: Upon treatment with 5-fluorouracil (5-FU), apoptosis was increased in latently infected ACH2 cells encoding competent p53 compared with uninfected parent A3.01 cells, while the apoptosis of latently infected p53 null J1.1 cells was less than that of uninfected cells. Treatment with 5-FU increased the levels of cleaved caspase-3 and PARP in ACH2 cells compared with uninfected and latently infected p53 null J1.1 cells. The levels of expression and activation of p53 were higher in both latently infected ACH2 and NCHA2 cells than in uninfected cells. Furthermore, the activation levels of p53 in both cells were further increased upon 5-FU treatment. Consistent with p53 status, apoptosis was markedly increased in ACH2 and NCHA2 cells compared with uninfected and latently infected J1.1 cells upon treatment with other anticancer drugs such as doxorubicin and etoposide. Inhibition of p53 in cells with latent HIV-1 infection diminished apoptosis upon 5-FU treatment. CONCLUSION: Evidence described here indicate that when treated with anticancer drugs, apoptosis of cells with latent HIV-1 infection was increased via the p53 activation pathway and may provide information for application of anticancer drugs to selectively eliminate HIV-1 reservoirs.

Immunomodulatory Function of the Tumor Suppressor p53 in Host Immune Response and the Tumor Microenvironment.

The tumor suppressor p53 is the most frequently mutated gene in human cancers. Most of the mutations are missense leading to loss of p53 function in inducing apoptosis and senescence. In addition to these autonomous effects of p53 inactivation/dysfunction on tumorigenesis, compelling evidence suggests that p53 mutation/inactivation also leads to gain-of-function or activation of non-autonomous pathways, which either directly or indirectly promote tumorigenesis. Experimental and clinical results suggest that p53 dysfunction fuels pro-tumor inflammation and serves as an immunological gain-of-function driver of tumorigenesis via skewing immune landscape of the tumor microenvironment (TME). It is now increasingly appreciated that p53 dysfunction in various cellular compartments of the TME leads to immunosuppression and immune evasion. Although our understanding of the cellular and molecular processes that link p53 activity to host immune regulation is still incomplete, it is clear that activating/reactivating the p53 pathway in the TME also represents a compelling immunological strategy to reverse immunosuppression and enhance antitumor immunity. Here, we review our current understanding of the potential cellular and molecular mechanisms by which p53 participates in immune regulation and discuss how targeting the p53 pathway can be exploited to alter the immunological landscape of tumors for maximizing therapeutic outcome.

Vulnerability of Antioxidant Drug Therapies on Targeting the Nrf2-Trp53-Jdp2 Axis in Controlling Tumorigenesis.

Control of oxidation/antioxidation homeostasis is important for cellular protective functions, and disruption of the antioxidation balance by exogenous and endogenous ligands can lead to profound pathological consequences of cancerous commitment within cells. Although cancers are sensitive to antioxidation drugs, these drugs are sometimes associated with problems including tumor resistance or dose-limiting toxicity in host animals and patients. These problems are often caused by the imbalance between the levels of oxidative stress-induced reactive oxygen species (ROS) and the redox efficacy of antioxidants. Increased ROS levels, because of abnormal function, including metabolic abnormality and signaling aberrations, can promote tumorigenesis and the progression of malignancy, which are generated by genome mutations and activation of proto-oncogene signaling. This hypothesis is supported by various experiments showing that the balance of oxidative stress and redox control is important for cancer therapy. Although many antioxidant drugs exhibit therapeutic potential, there is a heterogeneity of antioxidation functions, including cell growth, cell survival, invasion abilities, and tumor formation, as well as the expression of marker genes including tumor suppressor proteins, cell cycle regulators, nuclear factor erythroid 2-related factor 2, and Jun dimerization protein 2; their effectiveness in cancer remains unproven. Here, we summarize the rationale for the use of antioxidative drugs in preclinical and clinical antioxidant therapy of cancer, and recent advances in this area using cancer cells and their organoids, including the targeting of ROS homeostasis.

JinLiDa granules alleviates cardiac hypertrophy and inflammation in diabetic cardiomyopathy by regulating TP53.

BACKGROUND: JinLiDa granules (JLD) is a traditional Chinese medicine (TCM) used to treat type 2 diabetes mellitus with Qi and Yin deficiency. Clinical evidence has shown that JLD can alleviate diabetic cardiomyopathy, but the exact mechanism is not yet clear. PURPOSE: The purpose of this study was to examine the potential role and mechanism of JLD in the treatment of diabetic cardiomyopathy through network pharmacological analysis and basic experiments. METHODS: The targets of JLD associated with diabetic cardiomyopathy were examined by network pharmacology. Protein interaction analysis was performed on the targets, and the associated pathways were searched by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Diabetic mice were treated with low or high doses of JLD by gavage, and AC16 and H9C2 cardiomyocytes exposed to high-glucose conditions were treated with JLD. The analysis results were verified by various experimental techniques to examine molecular mechanisms. RESULTS: Network pharmacological analysis revealed that JLD acted on the tumor suppressor p53 (TP53) during inflammation and fibrosis associated with diabetic cardiomyopathy. The results of basic experiments showed that after JLD treatment, ventricular wall thickening in diabetic mouse hearts was attenuated, cardiac hypertrophy and myocardial inflammation were alleviated, and the expression of cardiac hypertrophy- and inflammation-related factors in cardiomyocytes exposed to a high-glucose environment was decreased. Cardiomyocyte morphology also improved after JLD treatment. TP53 expression and the tumor necrosis factor (TNF) and transforming growth factor beta-1 (TGFß1) signaling pathways were significantly altered, and inhibiting TP53 expression effectively alleviated the activation of the TNF and TGFß1 signaling pathways under high glucose conditions. Overexpression of TP53 activated these signaling pathways. CONCLUSIONS: JLD acted on TP53 to regulate the TNF and TGFß1 signaling pathways, effectively alleviating cardiomyocyte hypertrophy and inflammation in high glucose and diabetic conditions. Our study provides a solid foundation for the future treatment of diabetic cardiomyopathy with JLD.

Influence of the interaction between p53 and ZNF568 on mitochondrial oxidative phosphorylation.

The tumor suppressor p53 plays important roles in suppressing the development and progression of cancer by responding to various stress signals. In addition, p53 can regulate the metabolic pathways of cancer cells by regulating energy metabolism and oxidative phosphorylation. Here, we present a mechanism for the interaction between p53 and ZNF568. Initially, we used X-ray crystallography to determine the irregular loop structure of the ZNF568 KRAB domain; this loop plays an important role in the interaction between p53 and ZNF568. In addition, Cryo-EM was used to examine how the p53 DBD and ZNF568 KRAB domains bind together. The function of ZNF568 on p53-mediated mitochondrial respiration was confirmed by measuring glucose consumption and lactate production. These findings show that ZNF568 can reduce p53-mediated mitochondrial respiratory activity by binding to p53 and inhibiting the transcription of SCO2. SIGNIFICANCE: ZNF568 can directly bind to the p53 DBD and transcriptionally regulate the SCO2 gene. SCO2 transcriptional regulation by interaction between ZNF568 and p53 may regulate the balance between mitochondrial respiration and glycolysis.

Attenuation of aggressive tumor progression of anaplastic thyroid cancer by p53.

Anaplastic thyroid cancer (ATC) is the most aggressive thyroid cancer, with very limited treatment options. Mutations of p53 are associated with lethal outcomes of ATC. In this study, we tested the hypothesis that wild type p53 (WTp53) mitigates its aggressive progression. We used human 8505C cells (from human ATC tumors) as a model, harboring a BRAFV600E mutation and single of mutated p53C742G allele. We exogenously expressed WTp53 or mutant p53C742G into 8505C cells (8505C-WTp53 or 8505C-MTp53, respectively). The expressed WTp53 inhibited cell proliferation, decreased cell migration, and induced apoptosis via induction of proapoptotic WTp53 target BAX and PUMA genes in vitro. Mouse xenograft studies showed suppression of tumors induced by 8505C-WTp53 but not by 8505C-MTp53 cells. Consistent with in vitro findings, WTp53 inhibited proliferation of tumor cells, evidenced by decreased proliferation marker Ki-67 in tumors. WTp53 also induced apoptosis in xenograft tumors as shown by increased cleaved caspase-3 proteins and pro-apoptotic regulators, BAX and PUMA. Single cells RNA-sequencing (scRNA-seq) of tumors induced by 8505C, 8505C-WTp53, and 8505C-MTp53 cells demonstrated differential expression gene (DEG) patterns between 8505C-WTp53 and 8505C tumors. DEGs analysis identified alteration of multiple pathways, leading to attenuating the oncogenic actions of mutant p53. The discovery of the suppression of TNFα via NFκB pathway topped the pathways list, resulting in subduing the deleterious inflammatory responses caused by mutant p53. Our findings that exogenously expressed WTp53 could counter act the oncogenic actions of p53 has heightened the feasibility of using CRISPR/Cas9 genome editing to modify the p53 alleles for potential treatment of ATC.

p53 promotes antiviral innate immunity by driving hexosamine metabolism.

The tumor suppressor p53 controls cell fate decisions and prevents malignant transformation, but its functions in antiviral immunity remain unclear. Here, we demonstrate that p53 metabolically promotes antiviral innate immune responses to RNA viral infection. p53-deficient macrophages or mice display reduced expression of glutamine fructose-6-phosphate amidotransferase 2 (GFPT2), a key enzyme of the hexosamine biosynthetic pathway (HBP). Through transcriptional upregulation of GFPT2, p53 drives HBP activity and de novo synthesis of UDP-GlcNAc, which in turn leads to the O-GlcNAcylation of mitochondrial antiviral signaling protein (MAVS) and UBX-domain-containing protein 1 (UBXN1) during virus infection. Moreover, O-GlcNAcylation of UBXN1 blocks its interaction with MAVS, thereby further liberating MAVS for tumor necrosis factor receptor-associated factor 3 binding to activate TANK-binding kinase 1-interferon (IFN) regulatory factor 3 signaling cascades and IFN-ß production. Genetic or pharmaceutical inhibition of GFPT efficiently reduces MAVS activation and abrogates the antiviral innate immunity promoted by p53 in vitro and in vivo. Our findings reveal that p53 drives HBP activity and O-GlcNAcylation of UBXN1 and MAVS to enhance IFN-ß-mediated antiviral innate immunity.

p53 and MYC-regulated squalene epoxidase as Achilles heel in colorectal cancer.

The transcription factors p53 and MYC are often considered non-druggable targets, but their dysregulation can generate new dependencies and treatment opportunities in cancer cells. The p53 and MYC-regulated squalene epoxidase (SQLE) has been identified as a potential Achilles heel in colorectal cancer. This is of great interest because the FDA-approved anti-fungal SQLE inhibitor Terbinafine could be repurposed to treat colorectal cancer patients.