Acetylation is indispensable for p53 activation

Structural and mechanistic diversity in p53-mediated regulation of organismal longevity across taxonomical orders

The accumulation of senescent cells induces several aging phenotypes, and the p53 tumor suppressor protein regulates one of the two known cellular senescence pathways. p53's regulation of senescence is however not clear. For example, p53 deficiency in some mice has been shown to rescue premature aging while others display significant aging phenotype when p53-deficient. This study seeks to elucidate, structurally and mechanistically, p53's roles in longevity. Through a relative evolutionary scoring (RES) algorithm, we quantify the level of evolutionary change in the residues of p53 across organisms of varying average lifespans in six taxonomic orders. Secondly, we used PEPPI to assess the likelihood of interaction between p53-or p53-linked proteins-and known senescence-regulating proteins across organisms in the orders Primates and Perciformes. Our RES algorithm found variations in the alignments within and across orders, suggesting that mechanisms of p53-mediated regulation of longevity may vary. PEPPI results suggest that longer-lived species may have evolved to regulate induction and inhibition of cellular senescence better than their shorter-lived counterparts. With experimental verification, these predictions could help elucidate the mechanisms of p53-mediated cellular senescence, ultimately clarifying our understanding of p53's connection to aging in a multiple-species context.

Author summary

The p53 tumor suppressor protein protects our genome from cancers by repairing DNA damage, regulating cell death and/or pushing cells to a state where they become permanently unable to divide (known as cellular senescence). An accumulation of senescent cells produces various molecular features of aging in both mouse and human cellular models-thus linking p53 to the aging process. However, the molecular mechanism by which p53 regulates aging and its structural implications on this regulation are not clear. In this study, we assessed quantitatively the evolutionary differences in p53 sequences of organisms across several taxonomical orders to determine if there is a relationship between average lifespan and sequence evolution. In addition, we used a protein-protein interaction tool to assess the likelihood of interaction between p53, or p53-associated protein, and various senescence-associated proteins across organisms of various lifespans in two taxonomic orders: Primates and Perciformes. An elucidation of p53 structural difference and mechanistic proteomic network linked to p53 regulation of cellular senescence could advance therapeutics targeting abnormal aging.

USP19 Negatively Regulates p53 and Promotes Cervical Cancer Progression

p53 is a tumor suppressor gene activated in response to cellular stressors that inhibits cell cycle progression and induces pro-apoptotic signaling. The protein level of p53 is well balanced by the action of several E3 ligases and deubiquitinating enzymes (DUBs). Several DUBs have been reported to negatively regulate and promote p53 degradation in tumors. In this study, we identified USP19 as a negative regulator of p53 protein level. We demonstrate a direct interaction between USP19 and p53 by pull down assay. The overexpression of USP19 promoted ubiquitination of p53 and reduced its protein half-life. We also demonstrate that CRISPR/Cas9-mediated knockout of USP19 in cervical cancer cells elevates p53 protein levels, resulting in reduced colony formation, cell migration, and cell invasion. Overall, our results indicate that USP19 negatively regulates p53 protein levels in cervical cancer progression.

A Barth Syndrome Patient-Derived D75H Point Mutation in TAFAZZIN Drives Progressive Cardiomyopathy in Mice

Cardiomyopathy is the predominant defect in Barth syndrome (BTHS) and is caused by a mutation of the X-linked Tafazzin (TAZ) gene, which encodes an enzyme responsible for remodeling mitochondrial cardiolipin. Despite the known importance of mitochondrial dysfunction in BTHS, how specific TAZ mutations cause diverse BTHS heart phenotypes remains poorly understood. We generated a patient-tailored CRISPR/Cas9 knock-in mouse allele (TazPM) that phenocopies BTHS clinical traits. As TazPM males express a stable mutant protein, we assessed cardiac metabolic dysfunction and mitochondrial changes and identified temporally altered cardioprotective signaling effectors. Specifically, juvenile TazPM males exhibit mild left ventricular dilation in systole but have unaltered fatty acid/amino acid metabolism and normal adenosine triphosphate (ATP). This occurs in concert with a hyperactive p53 pathway, elevation of cardioprotective antioxidant pathways, and induced autophagy-mediated early senescence in juvenile TazPM hearts. However, adult TazPM males exhibit chronic heart failure with reduced growth and ejection fraction, cardiac fibrosis, reduced ATP, and suppressed fatty acid/amino acid metabolism. This biphasic changeover from a mild-to-severe heart phenotype coincides with p53 suppression, downregulation of cardioprotective antioxidant pathways, and the onset of terminal senescence in adult TazPM hearts. Herein, we report a BTHS genotype/phenotype correlation and reveal that absent Taz acyltransferase function is sufficient to drive progressive cardiomyopathy.

Recent Advances on Mutant p53: Unveiling Novel Oncogenic Roles, Degradation Pathways, and Therapeutic Interventions

The p53 protein is the master regulator of cellular integrity, primarily due to its tumor-suppressing functions. Approximately half of all human cancers carry mutations in the TP53 gene, which not only abrogate the tumor-suppressive functions but also confer p53 mutant proteins with oncogenic potential. The latter is achieved through so-called gain-of-function (GOF) mutations that promote cancer progression, metastasis, and therapy resistance by deregulating transcriptional networks, signaling pathways, metabolism, immune surveillance, and cellular compositions of the microenvironment. Despite recent progress in understanding the complexity of mutp53 in neoplastic development, the exact mechanisms of how mutp53 contributes to cancer development and how they escape proteasomal and lysosomal degradation remain only partially understood. In this review, we address recent findings in the field of oncogenic functions of mutp53 specifically regarding, but not limited to, its implications in metabolic pathways, the secretome of cancer cells, the cancer microenvironment, and the regulating scenarios of the aberrant proteasomal degradation. By analyzing proteasomal and lysosomal protein degradation, as well as its connection with autophagy, we propose new therapeutical approaches that aim to destabilize mutp53 proteins and deactivate its oncogenic functions, thereby providing a fundamental basis for further investigation and rational treatment approaches for TP53-mutated cancers.

Is autism a PIN1 deficiency syndrome? A proposed etiological role for glyphosate

Autism is a neurodevelopmental disorder, the prevalence of which has increased dramatically in the United States over the past two decades. It is characterized by stereotyped behaviors and impairments in social interaction and communication. In this paper, we present evidence that autism can be viewed as a PIN1 deficiency syndrome. Peptidyl-prolyl cis/trans isomerase, NIMA-Interacting 1 (PIN1) is a peptidyl-prolyl cis/trans isomerase, and it has widespread influences in biological organisms. Broadly speaking, PIN1 deficiency is linked to many neurodegenerative diseases, whereas PIN1 over-expression is linked to cancer. Death-associated protein kinase 1 (DAPK1) strongly inhibits PIN1, and the hormone melatonin inhibits DAPK1. Melatonin deficiency is strongly linked to autism. It has recently been shown that glyphosate exposure to rats inhibits melatonin synthesis as a result of increased glutamate release from glial cells and increased expression of metabotropic glutamate receptors. Glyphosate's inhibition of melatonin leads to a reduction in PIN1 availability in neurons. In this paper, we show that PIN1 deficiency can explain many of the unique morphological features of autism, including increased dendritic spine density, missing or thin corpus callosum, and reduced bone density. We show how PIN1 deficiency disrupts the functioning of powerful high-level signaling molecules, such as nuclear factor erythroid 2-related factor 2 (NRF2) and p53. Dysregulation of both of these proteins has been linked to autism. Severe depletion of glutathione in the brain resulting from chronic exposure to oxidative stressors and extracellular glutamate leads to oxidation of the cysteine residue in PIN1, inactivating the protein and further contributing to PIN1 deficiency. Impaired autophagy leads to increased sensitivity of neurons to ferroptosis. It is imperative that further research be conducted to experimentally validate whether the mechanisms described here take place in response to chronic glyphosate exposure and whether this ultimately leads to autism.

4-(Benzyloxy)phenol-induced p53 exhibits antimycobacterial response triggering phagosome-lysosome fusion through ROS-dependent intracellular Ca2+ pathway in THP-1 cells

Drug-resistant tuberculosis (TB) outbreak has emerged as a global public health crisis. Therefore, new and innovative therapeutic options like host-directed therapies (HDTs) through novel modulators are urgently required to overcome the challenges associated with TB. In the present study, we have investigated the anti-mycobacterial effect of 4-(Benzyloxy)phenol. Cell-viability assay asserted that 50 μM of 4-(Benzyloxy)phenol was not cytotoxic to phorbol 12-myristate 13-acetate (PMA) differentiated THP-1 (dTHP-1) cells. It was observed that 4-(Benzyloxy)phenol activates p53 expression by hindering its association with KDM1A. Increased ROS, intracellular Ca2+ and phagosome-lysosome fusion, were also observed upon 4-(Benzyloxy)phenol treatment. 4-(Benzyloxy)phenol mediated killing of intracellular mycobacteria was abrogated in the presence of specific inhibitors of ROS, Ca2+ and phagosome-lysosome fusion like NAC, BAPTA-AM, and W7, respectively. We further demonstrate that 4-(Benzyloxy)phenol mediated enhanced ROS production is mediated by acetylation of p53. Blocking of p53 acetylation by Pifithrin-α (PFT- α) enhanced intracellular mycobacterial growth by blocking the mycobactericidal effect of 4-(Benzyloxy)phenol. Altogether, the results showed that 4-(Benzyloxy)phenol executed its anti-mycobacterial effect by modulating p53-mediated ROS production to regulate phagosome-lysosome fusion through Ca2+ production.

Mechanisms and therapeutic strategies for senescence-associated secretory phenotype in the intervertebral disc degeneration microenvironment

As a permanent state of cell cycle arrest, cellular senescence has become an important factor in aging and age-related diseases. As a central regulator of physiology and pathology associated with cellular senescence, the senescence associated secretory phenotype can create an inflammatory and catabolic environment through autocrine and paracrine ways, ultimately affecting tissue microstructure. As an age-related disease, the correlation between intervertebral disc degeneration and cellular senescence has been confirmed by many studies. Various pathological factors in the microenvironment of intervertebral disc degeneration promote senescent cells to produce and accumulate and express excessive senescence associated secretory phenotype. In this case, senescence associated secretory phenotype has received considerable attention as a potential target for delaying or treating disc degeneration. Therefore, we reviewed the latest research progress of senescence associated secretory phenotype, related regulatory mechanisms and intervertebral disc cell senescence treatment strategies. It is expected that further understanding of the underlying mechanism between cellular senescence pathology and intervertebral disc degeneration will help to formulate reasonable senescence regulation strategies, so as to achieve ideal therapeutic effects.

The translational potential of this article

Existing treatment strategies often fall short in addressing the challenge of repairing intervertebral disc Intervertebral disc degeneration（IVD） degeneration. The accumulation of senescent cells and the continuous release of senescence-associated secretory phenotype (SASP) perpetually impede disc homeostasis and hinder tissue regeneration. This impairment in repair capability presents a significant obstacle to the practical clinical implementation of strategies for intervertebral disc degeneration. As a result, we present a comprehensive overview of the latest advancements in research, the associated regulatory mechanisms, and strategies for treating SASP in IVD cells. This article aims to investigate effective interventions for delaying the onset and progression of age-related intervertebral disc degeneration. In an era where the aging population is becoming increasingly prominent, this endeavor holds paramount practical and translational significance.

The Protein Acetylation after Traumatic Spinal Cord Injury: Mechanisms and Therapeutic Opportunities

Spinal cord injury (SCI) leads to deficits of various normal functions and is difficult to return to a normal state. Histone and non-histone protein acetylation after SCI is well documented and regulates spinal cord plasticity, axonal growth, and sensory axon regeneration. However, our understanding of protein acetylation after SCI is still limited. In this review, we summarize current research on the role of acetylation of histone and non-histone proteins in regulating neuron growth and axonal regeneration in SCI. Furthermore, we discuss inhibitors and activators targeting acetylation-related enzymes, such as α-tubulin acetyltransferase 1 (αTAT1), histone deacetylase 6 (HDAC6), and sirtuin 2 (SIRT2), to provide promising opportunities for recovery from SCI. In conclusion, a comprehensive understanding of protein acetylation and deacetylation in SCI may contribute to the development of SCI treatment.

Development and Nanoparticle-Mediated Delivery of Novel MDM2/MDM4 Heterodimer Peptide Inhibitors to Enhance 5-Fluorouracil Nucleolar Stress in Colorectal Cancer Cells

Colorectal cancer (CRC) often involves wild-type p53 inactivation by MDM2 and MDM4 overexpression, promoting tumor progression and resistance to 5-fluoruracil (5-FU). Disrupting the MDM2/4 heterodimer can proficiently reactivate p53, sensitizing cancer cells to 5-FU. Herein, we developed 16 peptides based on Pep3 (1), the only known peptide acting through this mechanism. The new peptides, notably 3 and 9, showed lower IC50 values than 1. When incorporated into tumor-targeted biodegradable nanoparticles, these exhibited cytotoxicity against three different CRC cell lines. Notably, NPs/9 caused a significant increase in p53 levels associated with a strong increment of its main downstream target p21 inducing apoptosis. Also, the combined treatment of 9 with 5-FU caused the activation of nucleolar stress and a synergic apoptotic effect. Hence, the co-delivery of MDM2/4 heterodimer disruptors with 5-FU through nanoparticles might be a promising strategy to overcome drug resistance in CRC.

Pancreatic Neuroendocrine Tumors: Signaling Pathways and Epigenetic Regulation

Pancreatic neuroendocrine tumors (PNETs) are characterized by dysregulated signaling pathways that are crucial for tumor formation and progression. The efficacy of traditional therapies is limited, particularly in the treatment of PNETs at an advanced stage. Epigenetic alterations profoundly impact the activity of signaling pathways in cancer development, offering potential opportunities for drug development. There is currently a lack of extensive research on epigenetic regulation in PNETs. To fill this gap, we first summarize major signaling events that are involved in PNET development. Then, we discuss the epigenetic regulation of these signaling pathways in the context of both PNETs and commonly occurring-and therefore more extensively studied-malignancies. Finally, we will offer a perspective on the future research direction of the PNET epigenome and its potential applications in patient care.

Evidence of Histone H2A.Z Deacetylation and Cardiomyocyte Dedifferentiation in Infarcted/Tip60-depleted Hearts

Myocardial infarction (MI) in the human heart causes death of billions of cardiomyocytes (CMs), resulting in cardiac dysfunction that is incompatible with life or lifestyle. In order to re-muscularize injured myocardium, replacement CMs must be generated via renewed proliferation of surviving CMs. Approaches designed to induce proliferation of CMs after injury have been insufficient. Toward this end, we are targeting the Tip60 acetyltransferase, based on the rationale that its pleiotropic functions conspire to block the CM cell-cycle at several checkpoints. We previously reported that genetic depletion of Tip60 in a mouse model after MI reduces scarring, retains cardiac function, and activates the CM cell-cycle, although it is unclear whether this culminates in the generation of daughter CMs. For pre-existing CMs in the adult heart to resume proliferation, it is becoming widely accepted that they must first dedifferentiate, a process highlighted by loss of maturity, epithelial to mesenchymal transitioning (EMT), and reversion from fatty acid oxidation to glycolytic metabolism, accompanied by softening of the myocardial extracellular matrix. Findings in hematopoietic stem cells, and more recently in neural progenitor cells, have shown that Tip60 induces and maintains the differentiated state via site-specific acetylation of the histone variant H2A.Z. Here, we report that genetic depletion of Tip60 from naïve or infarcted hearts results in the near-complete absence of acetylated H2A.Z in CM nuclei, and that this is accordingly accompanied by altered gene expressions indicative of EMT induction, ECM softening, decreased fatty acid oxidation, and depressed expression of genes that regulate the TCA cycle. These findings, combined with our previous work, support the notion that because Tip60 has multiple targets that combinatorially maintain the differentiated state and inhibit proliferation, its transient therapeutic targeting to ameliorate the effects of cardiac injury should be considered.

Regulated secretion of mutant p53 negatively affects T lymphocytes in the tumor microenvironment

Several studies have demonstrated the role of the oncogenic mutant p53 in promoting tumor progression; however, there is limited information on the effects of secreted oncogenic mutant p53 on the tumor microenvironment and tumor immune escape. In this study, we found that secretion of mutant p53, determined by exosome content, is dependent on its N-terminal dileucine motif via its binding to β-adaptin, and inhibited by the CHK2-mediated-Ser 20 phosphorylation. Moreover, we observed that the mutant p53 caused downregulation and dysfunction of CD4+ T lymphocytes in vivo and downregulated the levels and activities of rate-limiting glycolytic enzymes in vitro. Furthermore, inhibition of mutant p53 secretion by knocking down AP1B1 or mutation of dileucine motif could reverse the quantity and function of CD4+ T lymphocytes and restrain the tumor growth. Our study demonstrates that the tumor-derived exosome-mediated secretion of oncogenic mutant p53 inhibits glycolysis to alter the immune microenvironment via functional suppression of CD4+ T cells, which may be the underlying mechanism for tumor immune escape. Therefore, targeting TDE-mediated p53 secretion may serve as a potential therapeutic target for cancer treatment.

Acetylation and deacetylation of histone in adipocyte differentiation and the potential significance in cancer

Adipocytes are derived from pluripotent mesenchymal stem cells and can develop into several cell types including adipocytes, myocytes, chondrocytes, and osteocytes. Adipocyte differentiation is regulated by a variety of transcription factors and signaling pathways. Various epigenetic factors, particularly histone modifications, play key roles in adipocyte differentiation and have indispensable functions in altering chromatin conformation. Histone acetylases and deacetylases participate in the regulation of protein acetylation, mediate transcriptional and post-translational modifications, and directly acetylate or deacetylate various transcription factors and regulatory proteins. The adipocyte differentiation of stem cells plays a key role in various metabolic diseases. Cancer stem cells(CSCs) play an important function in cancer metastasis, recurrence, and drug resistance, and have the characteristics of stem cells. They are expressed in various cell lineages, including adipocytes. Recent studies have shown that cancer stem cells that undergo epithelial-mesenchymal transformation can undergo adipocytic differentiation, thereby reducing the degree of malignancy. This opens up new possibilities for cancer treatment. This review summarizes the regulation of acetylation during adipocyte differentiation, involving the functions of histone acetylating and deacetylating enzymes as well as non-histone acetylation modifications. Mechanistic studies on adipogenesis and acetylation during the differentiation of cancer cells into a benign cell phenotype may help identify new targets for cancer treatment.

Unbiased interrogation of functional lysine residues in human proteome

CRISPR screens have empowered the high-throughput dissection of gene functions; however, more explicit genetic elements, such as codons of amino acids, require thorough interrogation. Here, we establish a CRISPR strategy for unbiasedly probing functional amino acid residues at the genome scale. By coupling adenine base editors and barcoded sgRNAs, we target 215,689 out of 611,267 (35%) lysine codons, involving 85% of the total protein-coding genes. We identify 1,572 lysine codons whose mutations perturb human cell fitness, with many of them implicated in cancer. These codons are then mirrored to gene knockout screen data to provide functional insights into the role of lysine residues in cellular fitness. Mining these data, we uncover a CUL3-centric regulatory network in which lysine residues of CUL3 CRL complex proteins control cell fitness by specifying protein-protein interactions. Our study offers a general strategy for interrogating genetic elements and provides functional insights into the human proteome.

Clinical and functional analysis of the germline TP53 p.K164E acetylation site variant

TP53 plays a critical role as a tumor suppressor by controlling cell cycle progression, DNA repair, and apoptosis. Post-translational modifications such as acetylation of specific lysine residues in the DNA binding and carboxy-terminus regulatory domains modulate its tumor suppressor activities. In this study, we addressed the functional consequences of the germline TP53 p.K164E (NM_000546.5: c.490A>G) variant identified in a patient with early-onset breast cancer and a significant family history of cancer. K164 is a conserved residue located in the L2 loop of the p53 DNA binding domain that is post-translationally modified by acetylation. In silico, in vitro, and in vivo analyses demonstrated that the glutamate substitution at K164 marginally destabilizes the p53 protein structure but significantly impairs sequence-specific DNA binding, transactivation, and tumor cell growth inhibition. Although p.K164E is currently considered a variant of unknown significance by different clinical genetic testing laboratories, the clinical and laboratory-based findings presented here provide strong evidence to reclassify TP53 p.K164E as a likely pathogenic variant.

A combinatorial therapeutic approach to enhance FLT3-ITD AML treatment

Internal tandem duplication mutations of the FMS-like tyrosine kinase-3 (FLT3-ITDs) occur in 25%-30% of patients with acute myeloid leukemia (AML) and are associated with dismal prognosis. Although FLT3 inhibitors have demonstrated initial clinical efficacy, the overall outcome of patients with FLT3-ITD AML remains poor, highlighting the urgency to develop more effective treatment strategies. In this study, we reveal that FLT3 inhibitors reduced protein stability of the anti-cancer protein p53, resulting in drug resistance. Blocking p53 degradation with proteasome inhibitors restores intracellular p53 protein levels and, in combination with FLT3-ITD inhibitors, shows superior therapeutic effects against FLT3-ITD AML in cells, mouse models, and patients. These data suggest that this combinatorial therapeutic approach may represent a promising strategy to target FLT3-ITD AML.

An engineered nanoplatform cascade to relieve extracellular acidity and enhance resistance-free chemotherapy

Tumor extracellular acidity and chemoresistance are regarded as the main obstacles to achieving optimal chemotherapeutic efficacy in tumor therapy. Herein, a new kind of acid-cascade P-S-Z nanoparticles (NPs) is developed to relieve extracellular acidosis and enhance chemotherapy without causing drug resistance. The P-S-Z NPs selectively accumulate in tumors and then regulate the release of S-Z NPs containing syrosingopine (Syr) and acid-activated prodrug ZMC1-Pt depending on the extracellular acidity. Benefiting from their small size and positive surface charge, S-Z NPs are easily internalized by tumor cells in deep tumor tissue, facilitating the release of Syr to inhibit lactic acid excretion and ultimately enhance cell acidosis. The prolonged intracellular acidosis not only inhibits tumor cell proliferation, but also continuously triggers the activation of ZMC1-Pt prodrug, a platinum-based chemotherapeutic drug that effectively eliminates cancer cells and restores wild-type p53 function to prevent tumor chemoresistance. As a proof of concept, this is a promising strategy to transfer the adverse effect of intracellular acidosis to facilitate chemotherapy. This well-designed delivery system effectively kills tumor cells without causing significant tumor drug resistance, thus opening a new window to treat cancer.

SIRT1 is an actionable target to restore p53 function in HPV-associated cancer therapy

BACKGROUND

Our aim was to evaluate the efficacy and anti-cancer action of a precision medicine approach involving a novel SIRT1-dependent pathway that, when disrupted, leads to the restoration of a functional p53 in human papillomavirus (HPV)-transformed cells.

METHODS

The anticancer potential of inhibiting SIRT1 was evaluated by examining the effects of the specific SIRT1 inhibitor EX527 (also known as Selisistat) or genetic silencing, either individually or in conjunction with standard chemotherapeutic agents, on a range of HPV+ cancer cells and a preclinical mouse model of HPV16-induced cancer.

RESULTS

We show that SIRT1 inhibition restores a transcriptionally active K382-acetylated p53 in HPV+ but not HPV- cell lines, which in turn promotes G0/G1 cell cycle arrest and inhibits clonogenicity specifically in HPV+ cells. Additionally, EX527 treatment increases the sensitivity of HPV+ cells to sublethal doses of standard genotoxic agents. The enhanced sensitivity to cisplatin as well as p53 restoration were also observed in an in vivo tumorigenicity assay using syngeneic C3.43 cells harbouring an integrated HPV16 genome, injected subcutaneously into C57BL/6J mice.

CONCLUSIONS

Our findings uncover an essential role of SIRT1 in HPV-driven oncogenesis, which may have direct translational implications for the treatment of this type of cancer.

Disrupted Binding of Cystathionine γ-Lyase to p53 Promotes Endothelial Senescence

BACKGROUND

Advanced age is unequivocally linked to the development of cardiovascular disease; however, the mechanisms resulting in reduced endothelial cell regeneration remain poorly understood. Here, we investigated novel mechanisms involved in endothelial cell senescence that impact endothelial cell transcription and vascular repair after injury.

METHODS

Native endothelial cells were isolated from young (20±3.4 years) and aged (80±2.3 years) individuals and subjected to molecular analyses to assess global transcriptional and metabolic changes. In vitro studies were conducted using primary human and murine endothelial cells. A murine aortic re-endothelialization model was used to examine endothelial cell regenerative capacity in vivo.

RESULTS

RNA sequencing of native endothelial cells revealed that aging resulted in p53-mediated reprogramming to express senescence-associated genes and suppress glycolysis. Reduced glucose uptake and ATP contributed to attenuated assembly of the telomerase complex, which was required for endothelial cell proliferation. Enhanced p53 activity in aging was linked to its acetylation on K120 due to enhanced activity of the acetyltransferase MOZ (monocytic leukemic zinc finger). Mechanistically, p53 acetylation and translocation were, at least partially, attributed to the loss of the vasoprotective enzyme, CSE (cystathionine γ-lyase). CSE physically anchored p53 in the cytosol to prevent its nuclear translocation and CSE absence inhibited AKT (Protein kinase B)-mediated MOZ phosphorylation, which in turn increased MOZ activity and subsequently p53 acetylation. In mice, the endothelial cell-specific deletion of CSE activated p53, induced premature endothelial senescence, and arrested vascular repair after injury. In contrast, the adeno-associated virus 9-mediated re-expression of an active CSE mutant retained p53 in the cytosol, maintained endothelial glucose metabolism and proliferation, and prevented endothelial cell senescence. Adenoviral overexpression of CSE in native endothelial cells from aged individuals maintained low p53 activity and reactivated telomerase to revert endothelial cell senescence.

CONCLUSIONS

Aging-associated impairment of vascular repair is partly determined by the vasoprotective enzyme CSE.

A Boolean network model of the double-strand break repair pathway choice

Double strand break (DSB) repair is critical to maintaining the integrity of the genome. DSB repair deficiency underlies multiple pathologies, including cancer, chromosome instability syndromes, and, potentially, neurodevelopmental defects. DSB repair is mainly handled by two pathways: highly accurate homologous recombination (HR), which requires a sister chromatid for template-based repair, limited to S/G2 phases of the cell cycle, and canonical non-homologous end joining (c-NHEJ), available throughout the cell cycle in which minimum homology is sufficient for highly efficient yet error-prone repair. Some circumstances, such as cancer, require alternative highly mutagenic DSB repair pathways like microhomology-mediated end-joining (MMEJ) and single-strand annealing (SSA), which are triggered to attend to DNA damage. These non-canonical repair alternatives are emerging as prominent drivers of resistance in drug-based tumor therapies. Multiple DSB repair options require tight inter-pathway regulation to prevent unscheduled activities. In addition to this complexity, epigenetic modifications of the histones surrounding the DSB region are emerging as critical regulators of the DSB repair pathway choice. Modeling approaches to understanding DSBs repair pathway choice are advantageous to perform simulations and generate predictions on previously uncharacterized aspects of DSBs response. In this work, we present a Boolean network model of the DSB repair pathway choice that incorporates the knowledge, into a dynamic system, of the inter-pathways regulation involved in DSB repair, i.e., HR, c-NHEJ, SSA, and MMEJ. Our model recapitulates the well-characterized HR activity observed in wild-type cells in response to DSBs. It also recovers clinically relevant behaviors of BRCA1/FANCS mutants, and their corresponding drug resistance mechanisms ascribed to DNA repair gain-of-function pathogenic variants. Since epigenetic modifiers are dynamic and possible druggable targets, we incorporated them into our model to better characterize their involvement in DSB repair. Our model predicted that loss of the TIP60 complex and its corresponding histone acetylation activity leads to activation of SSA in response to DSBs. Our experimental validation showed that TIP60 effectively prevents activation of RAD52, a key SSA executor, and confirms the suitable use of Boolean network modeling for understanding DNA DSB repair.

Fine tuning of the transcription juggernaut: A sweet and sour saga of acetylation and ubiquitination

Among post-translational modifications of proteins, acetylation, phosphorylation, and ubiquitination are most extensively studied over the last several decades. Owing to their different target residues for modifications, cross-talk between phosphorylation with that of acetylation and ubiquitination is relatively less pronounced. However, since canonical acetylation and ubiquitination happen only on the lysine residues, an overlap of the same lysine residue being targeted for both acetylation and ubiquitination happens quite frequently and thus plays key roles in overall functional regulation predominantly through modulation of protein stability. In this review, we discuss the cross-talk of acetylation and ubiquitination in the regulation of protein stability for the functional regulation of cellular processes with an emphasis on transcriptional regulation. Further, we emphasize our understanding of the functional regulation of Super Elongation Complex (SEC)-mediated transcription, through regulation of stabilization by acetylation, deacetylation and ubiquitination and associated enzymes and its implication in human diseases.

SCARNA10 regulates p53 acetylation-dependent transcriptional activity

The tumor suppressor p53 is involved in variety of cell progresses including cell cycle arrest, apoptosis, DNA repair, senescence, cell metabolism and ferroptosis. Here, we identified lncRNA SCARNA10 (Small Cajal Body-Specific RNA 10) as a novel cellular factor that interacts with the DNA binding domain (DBD) of p53. Upon binding the DBD of p53 and CREB-binding protein (CBP), SCARNA10 promotes the acetylation of p53, and activates p53-mediated transcriptional activation. Overexpress or knockdown SCARNA10 leads to up (or down)-regulation of p53-mediated transcriptional activation, whereas not affecting p53 protein levels. Moreover, SCARNA10 directly activates transcription by increasing the acetylation of p53 C-terminal domain (CTD) without affecting p53 phosphorylation at Ser15. These results indicate that SCARNA10 is a novel factor which regulates p53 acetylation-dependent transcriptional activity and tumor suppression.

T-Cell Prolymphocytic Leukemia: Diagnosis, Pathogenesis, and Treatment

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells. Most patients with T-PLL present with lymphocytosis, anemia, thrombocytopenia, and hepatosplenomegaly. Correct identification of T-PLL is essential because treatment for this disease is distinct from that of other T-cell neoplasms. In 2019, the T-PLL International Study Group (TPLL-ISG) established criteria for the diagnosis, staging, and assessment of response to treatment of T-PLL with the goal of harmonizing research efforts and supporting clinical decision-making. T-PLL pathogenesis is commonly driven by T-cell leukemia 1 (TCL1) overexpression and ATM loss, genetic alterations that are incorporated into the TPLL-ISG diagnostic criteria. The cooperativity between TCL1 family members and ATM is seemingly unique to T-PLL across the spectrum of T-cell neoplasms. The role of the T-cell receptor, its downstream kinases, and JAK/STAT signaling are also emerging themes in disease pathogenesis and have obvious therapeutic implications. Despite improved understanding of disease pathogenesis, alemtuzumab remains the frontline therapy in the treatment of naïve patients with indications for treatment given its high response rate. Unfortunately, the responses achieved are rarely durable, and the majority of patients are not candidates for consolidation with hematopoietic stem cell transplantation. Improved understanding of T-PLL pathogenesis has unveiled novel therapeutic vulnerabilities that may change the natural history of this lymphoproliferative neoplasm and will be the focus of this concise review.

Acetylation Targeting Chimera Enables Acetylation of the Tumor Suppressor p53

With advances in chemically induced proximity technologies, heterobifunctional modalities such as proteolysis targeting chimeras (PROTACs) have been successfully advanced to clinics for treating cancer. However, pharmacologic activation of tumor-suppressor proteins for cancer treatment remains a major challenge. Here, we present a novel Acetylation Targeting Chimera (AceTAC) strategy to acetylate the p53 tumor suppressor protein. We discovered and characterized the first p53Y220C AceTAC, MS78, which recruits histone acetyltransferase p300/CBP to acetylate the p53Y220C mutant. MS78 effectively acetylated p53Y220C lysine 382 (K382) in a concentration-, time-, and p300-dependent manner and suppressed proliferation and clonogenicity of cancer cells harboring the p53Y220C mutation with little toxicity in cancer cells with wild-type p53. RNA-seq studies revealed novel p53Y220C-dependent upregulation of TRAIL apoptotic genes and downregulation of DNA damage response pathways upon acetylation induced by MS78. Altogether, the AceTAC strategy could provide a generalizable platform for targeting proteins, such as tumor suppressors, via acetylation.

Experimental Insights into the Interplay between Histone Modifiers and p53 in Regulating Gene Expression

Chromatin structure plays a fundamental role in regulating gene expression, with histone modifiers shaping the structure of chromatin by adding or removing chemical changes to histone proteins. The p53 transcription factor controls gene expression, binds target genes, and regulates their activity. While p53 has been extensively studied in cancer research, specifically in relation to fundamental cellular processes, including gene transcription, apoptosis, and cell cycle progression, its association with histone modifiers has received limited attention. This review explores the interplay between histone modifiers and p53 in regulating gene expression. We discuss how histone modifications can influence how p53 binds to target genes and how this interplay can be disrupted in cancer cells. This review provides insights into the complex mechanisms underlying gene regulation and their implications for potential cancer therapy.

Alternatively mechanistic insights into acetylation in p53-mediated transcriptional regulation of cancer cell-intrinsic PD-1

Since the recent discovery of cancer cell-intrinsic programmed cell death protein-1 (PD-1), the mechanisms that manipulate PD-1 functions in tumor development beyond its immune checkpoint roles have become attractive research topics in oncology. Our previous study validated that PD-1 exists in lung cancer cells and is directly transactivated by p53 in a DNA-binding domain (DBD) acetylation-dependent manner. Here, we report that the carboxyl-terminal domain (CTD) of p53 likewise participates in PD-1 transcriptional regulation in cancer cells under different regulatory mechanisms. By mutating the lysine residues within the CTD to mimic either acetylation-deficient or fully acetylated status, we proved that acetylated CTD dramatically impeded p53-mediated transactivation of PD-1. Furthermore, we identified bromodomain-containing protein 4 (BRD4) as a transcriptional coactivator of p53 that facilitates p53-mediated PD-1 transcription. Mechanistically, BRD4 specifically bound to the unacetylated CTD of p53, while CTD acetylation almost completely destroyed the BRD4-p53 interaction and thus led to compromised PD-1 expression. Collectively, this study unveils an alternative mechanism of p53 acetylation-directed PD-1 transcriptional regulation, which would broaden our current understanding of the molecular regulatory network of cancer cell-intrinsic PD-1.

Are inhibitors of histone deacetylase 8 (HDAC8) effective in hematological cancers especially acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL)?

Histone deacetylase 8 (HDAC8) aberrantly deacetylates histone and non-histone proteins. These include structural maintenance of chromosome 3 (SMC3) cohesin protein, retinoic acid induced 1 (RAI1), p53, etc and thus, regulating diverse processes such as leukemic stem cell (LSC) transformation and maintenance. HDAC8, one of the crucial HDACs, affects the gene silencing process in solid and hematological cancer progressions especially on acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). A specific HDAC8 inhibitor PCI-34051 showed promising results against both T-cell lymphoma and AML. Here, we summarize the role of HDAC8 in hematological malignancies, especially in AML and ALL. This article also introduces the structure/function of HDAC8 and a special attention has been paid to address the HDAC8 enzyme selectivity issue in hematological cancer especially against AML and ALL.

Affi-BAMS™: A Robust Targeted Proteomics Microarray Platform to Measure Histone Post-Translational Modifications

For targeted protein panels, the ability to specifically assay post-translational modifications (PTMs) in a quantitative, sensitive, and straightforward manner would substantially advance biological and pharmacological studies. The present study highlights the effectiveness of the Affi-BAMS™ epitope-directed affinity bead capture/MALDI MS platform for quantitatively defining complex PTM marks of H3 and H4 histones. Using H3 and H4 histone peptides and isotopically labelled derivatives, this affinity bead and MALDI MS platform achieves a range of >3 orders of magnitude with a technical precision CV of <5%. Using nuclear cellular lysates, Affi-BAMS PTM-peptide capture resolves heterogeneous histone N-terminal PTMs with as little as 100 µg of starting material. In an HDAC inhibitor and MCF7 cell line model, the ability to monitor dynamic histone H3 acetylation and methylation events is further demonstrated (including SILAC quantification). Affi-BAMS (and its capacity for the multiplexing of samples and target PTM-proteins) thus provides a uniquely efficient and effective approach for analyzing dynamic epigenetic histone marks, which is critical for the regulation of chromatin structure and gene expression.

MDM2 Implications for Potential Molecular Pathogenic Therapies of Soft-Tissue Tumors

Murine double minute 2 (MDM2, gene name MDM2) is an oncogene that mainly codes for a protein that acts as an E3 ubiquitin ligase, which targets the tumor suppressor protein p53 for degradation. Overexpression of MDM2 regulates the p53 protein levels by binding to it and promoting its degradation by the 26S proteasome. This leads to the inhibition of p53's ability to regulate cell cycle progression and apoptosis, allowing for uncontrolled cell growth, and can contribute to the development of soft-tissue tumors. The application of cellular stress leads to changes in the binding of MDM2 to p53, which prevents MDM2 from degrading p53. This results in an increase in p53 levels, which triggers either cell cycle arrest or apoptosis. Inhibiting the function of MDM2 has been identified as a potential therapeutic strategy for treating these types of tumors. By blocking the activity of MDM2, p53 function can be restored, potentially leading to tumor cell death and inhibiting the growth of tumors. However, further research is needed to fully understand the implications of MDM2 inhibition for the treatment of soft-tissue tumors and to determine the safety and efficacy of these therapies in clinical trials. An overview of key milestones and potential uses of MDM2 research is presented in this review.

The Role of NAD+, SIRTs Interactions in Stimulating and Counteracting Carcinogenesis

The World Health Organization has identified oncological diseases as one of the most serious health concerns of the current century. Current research on oncogenesis is focused on the molecular mechanisms of energy-biochemical reprogramming in cancer cell metabolism, including processes contributing to the Warburg effect and the pro-oncogenic and anti-oncogenic roles of sirtuins (SIRTs) and poly-(ADP-ribose) polymerases (PARPs). However, a clear understanding of the interaction between NAD⁺, SIRTs in cancer development, as well as their effects on carcinogenesis, has not been established, and literature data vary greatly. This work aims to provide a summary and structure of the available information on NAD⁺, SIRTs interactions in both stimulating and countering carcinogenesis, and to discuss potential approaches for pharmacological modulation of these interactions to achieve an anticancer effect.

VprBP/DCAF1 regulates p53 function and stability through site-specific phosphorylation

VprBP (also known as DCAF1) is a recently identified kinase that is overexpressed in cancer cells and serves as a major determinant for epigenetic gene silencing and tumorigenesis. The role of VprBP in driving target gene inactivation has been largely attributed to its ability to mediate histone H2A phosphorylation. However, whether VprBP also phosphorylates non-histone proteins and whether these phosphorylation events drive oncogenic signaling pathways have not been explored. Here we report that serine 367 phosphorylation (S367p) of p53 by VprBP is a key player in attenuating p53 transcriptional and growth suppressive activities. VprBP catalyzes p53S367p through a direct interaction with the C-terminal domain of p53. Mechanistically, VprBP-mediated S367p inhibits p53 function in the wake of promoting p53 proteasomal degradation, because blocking p53S367p increases p53 protein levels, thereby enhancing p53 transactivation. Furthermore, abrogation of VprBP-p53 interaction by p53 acetylation is critical for preventing p53S367p and potentiating p53 function in response to DNA damage. Together, our findings establish VprBP-mediated S367p as a negative regulator of p53 function and identify a previously uncharacterized mechanism by which S367p modulates p53 stability.

Sirtuin1-p53: a potential axis for cancer therapy

Sirtuin1 (SIRT1) is a conserved nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylase that plays key roles in a range of cellular events, including the maintenance of genome stability, gene regulation, cell proliferation, and apoptosis. P53 is one of the most studied tumor suppressors and the first identified non-histone target of SIRT1. SIRT1 deacetylates p53 in a NAD⁺-dependent manner and inhibits its transcriptional activity, thus exerting action on a series of pathways related to tissue homeostasis and various pathological states. The SIRT1-p53 axis is thought to play a central role in tumorigenesis. Although SIRT1 was initially identified as a tumor promoter, evidence now indicates that SIRT1 may also act as a tumor suppressor. This seemingly contradictory evidence indicates that the functionality of SIRT1 may be dictated by different cell types and intracellular localization patterns. In this review, we summarize recent evidence relating to the interactions between SIRT1 and p53 and discuss the relative roles of these two molecules with regards to cancer-associated cellular events. We also provide an overview of current knowledge of SIRT1-p53 signaling in tumorigenesis. Given the vital role of the SIRT1-p53 pathway, targeting this axis may provide promising strategies for the treatment of cancer.

SIRT1 activation synergizes with FXR agonism in hepatoprotection via governing nucleocytoplasmic shuttling and degradation of FXR

Farnesoid X receptor (FXR) is widely accepted as a promising target for various liver diseases; however, panels of ligands in drug development show limited clinical benefits, without a clear mechanism. Here, we reveal that acetylation initiates and orchestrates FXR nucleocytoplasmic shuttling and then enhances degradation by the cytosolic E3 ligase CHIP under conditions of liver injury, which represents the major culprit that limits the clinical benefits of FXR agonists against liver diseases. Upon inflammatory and apoptotic stimulation, enhanced FXR acetylation at K217, closed to the nuclear location signal, blocks its recognition by importin KPNA3, thereby preventing its nuclear import. Concomitantly, reduced phosphorylation at T442 within the nuclear export signals promotes its recognition by exportin CRM1, and thereby facilitating FXR export to the cytosol. Acetylation governs nucleocytoplasmic shuttling of FXR, resulting in enhanced cytosolic retention of FXR that is amenable to degradation by CHIP. SIRT1 activators reduce FXR acetylation and prevent its cytosolic degradation. More importantly, SIRT1 activators synergize with FXR agonists in combating acute and chronic liver injuries. In conclusion, these findings innovate a promising strategy to develop therapeutics against liver diseases by combining SIRT1 activators and FXR agonists.

Protein adduction causes non-mutational inhibition of p53 tumor suppressor

p53 is a key tumor suppressor that is frequently mutated in human tumors. In this study, we investigated how p53 is regulated in precancerous lesions prior to mutations in the p53 gene. Analyzing esophageal cells in conditions of genotoxic stress that promotes development of esophageal adenocarcinoma, we find that p53 protein is adducted with reactive isolevuglandins (isoLGs), products of lipid peroxidation. Modification of p53 protein with isoLGs diminishes its acetylation and binding to the promoters of p53 target genes causing modulation of p53-dependent transcription. It also leads to accumulation of adducted p53 protein in intracellular amyloid-like aggregates that can be inhibited by isoLG scavenger 2-HOBA in vitro and in vivo. Taken together, our studies reveal a posttranslational modification of p53 protein that causes molecular aggregation of p53 protein and its non-mutational inactivation in conditions of DNA damage that may play an important role in human tumorigenesis.

Unmasking the biological function and regulatory mechanism of NOC2L: a novel inhibitor of histone acetyltransferase

NOC2 like nucleolar associated transcriptional repressor (NOC2L) was recently identified as a novel inhibitor of histone acetyltransferase (INHAT). NOC2L is found to have two INHAT function domains and regulates histone acetylation in a histone deacetylases (HDAC) independent manner, which is distinct from other INHATs. In this review, we summarize the biological function of NOC2L in histone acetylation regulation, P53-mediated transcription, ribosome RNA processing, certain development events and carcinogenesis. We propose that NOC2L may be explored as a potential biomarker and a therapeutic target in clinical practice.

Ketogenic Diets and Mitochondrial Function: Benefits for Aging But Not for Athletes

As humans age, we lose skeletal muscle mass, even in the absence of disease (sarcopenia), increasing the risk of death. Low mitochondrial mass and activity contributes to sarcopenia. It is our hypothesis that a ketogenic diet improves skeletal muscle mitochondrial mass and function when they have declined because of aging or disease, but not in athletes where mitochondrial quality is high.

Targeting epigenetic regulation for cancer therapy using small molecule inhibitors

Cancer cells display pervasive changes in DNA methylation, disrupted patterns of histone posttranslational modification, chromatin composition or organization and regulatory element activities that alter normal programs of gene expression. It is becoming increasingly clear that disturbances in the epigenome are hallmarks of cancer, which are targetable and represent attractive starting points for drug creation. Remarkable progress has been made in the past decades in discovering and developing epigenetic-based small molecule inhibitors. Recently, epigenetic-targeted agents in hematologic malignancies and solid tumors have been identified and these agents are either in current clinical trials or approved for treatment. However, epigenetic drug applications face many challenges, including low selectivity, poor bioavailability, instability and acquired drug resistance. New multidisciplinary approaches are being designed to overcome these limitations, e.g., applications of machine learning, drug repurposing, high throughput virtual screening technologies, to identify selective compounds with improved stability and better bioavailability. We provide an overview of the key proteins that mediate epigenetic regulation that encompass histone and DNA modifications and discuss effector proteins that affect the organization of chromatin structure and function as well as presently available inhibitors as potential drugs. Current anticancer small-molecule inhibitors targeting epigenetic modified enzymes that have been approved by therapeutic regulatory authorities across the world are highlighted. Many of these are in different stages of clinical evaluation. We also assess emerging strategies for combinatorial approaches of epigenetic drugs with immunotherapy, standard chemotherapy or other classes of agents and advances in the design of novel epigenetic therapies.

Cutaneous T-cell lymphomas: 2023 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or the blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Long non-coding RNA TILR constitutively represses TP53 and apoptosis in lung cancer

Non-coding RNAs have an integral regulatory role in numerous functions related to lung cancer development. Here, we report identification of a novel lncRNA, termed TP53-inhibiting lncRNA (TILR), which was found to function as a constitutive negative regulator of p53 expression, including activation of downstream genes such as p21 and MDM2, and induction of apoptosis. A proteomic search for TILR-associated proteins revealed an association with PCBP2, while the mid-portion of TILR was found to be required for both PCBP2 and p53 mRNA binding. In addition, depletion of PCBP2 resulted in phenocopied effects of TILR silencing. TILR was also shown to suppress p53 expression in a post-transcriptional manner, as well as via a positive feedback loop involving p53 and Fanconi anemia pathway genes. Taken together, the present findings clearly demonstrate that TILR constitutively inhibits p53 expression in cooperation with PCBP2, thus maintaining p53 transcriptional activity at a level sufficiently low for avoidance of spurious apoptosis induction.

Mapping Interactions of the Intrinsically Disordered C-Terminal Regions of Tetrameric p53 by Segmental Isotope Labeling and NMR

The C-terminal region of the tumor suppressor protein p53 contains three domains, nuclear localization signal (NLS), tetramerization domain (TET), and C-terminal regulatory domain (CTD), which are essential for p53 function. Characterization of the structure and interactions of these domains within full-length p53 has been limited by the overall size and flexibility of the p53 tetramer. Using trans-intein splicing, we have generated full-length p53 constructs in which the C-terminal region is isotopically labeled with 15N for NMR analysis, allowing us to obtain atomic-level information on the C-terminal domains in the context of the full-length protein. Resonances of NLS and CTD residues have narrow linewidths, showing that these regions are largely solvent-exposed and dynamically disordered, whereas resonances from the folded TET are broadened beyond detection. Two regions of the CTD, spanning residues 369-374 and 381-388 and with high lysine content, make dynamic and sequence-independent interactions with DNA in regions that flank the p53 recognition element. The population of DNA-bound states increases as the length of the flanking regions is extended up to approximately 20 base pairs on either side of the recognition element. Acetylation of K372, K373, and K382, using a construct of the transcriptional coactivator CBP containing the TAZ2 and acetyltransferase domains, inhibits interaction of the CTD with DNA. This work provides high-resolution insights into the behavior of the intrinsically disordered C-terminal regions of p53 within the full-length tetramer and the molecular basis by which the CTD mediates DNA binding and specificity.

STYK1/NOK affects cell cycle late mitosis and directly interacts with anaphase-promoting complex activator CDH1

The novel oncogene STYK1/NOK plays critical roles in cancer development. However, its regulation during cell division is less defined. In this paper, we show that over-expression of STYK1/NOK caused mitotic arrest and cytokinesis defects. The protein level of STYK/NOK fluctuated during the cell cycle, with a peak at mitosis and a quick reduction upon mitotic exit. The cell cycle-related expression pattern of STYK1/NOK resembled the one of aurora kinases and polo-like kinase 1. Depletion of APC3 led to accumulation of STYK1/NOK and to the G2/M arrest. Co-immunoprecipitation experiment demonstrated the direct interaction of STYK1/NOK with CDH1. Overexpression of CDH1 shortened the half-life of STYK1/NOK. The kinase domain, but not the five D boxes, of STYK1/NOK was responsible for the interaction with CDH1. Altogether, our data demonstrated for the first time that STYK1/NOK could affect cell division, probably by directly targeting key components of APC/C such as CDH1 at late mitosis. Current study may provide a vital mechanistic clue for understanding the roles of STYK1/NOK in mitosis and cytokinesis during STYK1NOK mediated genomic instability and oncogenesis.

The phosphorylation to acetylation/methylation cascade in transcriptional regulation: how kinases regulate transcriptional activities of DNA/histone-modifying enzymes

Transcription factors directly regulate gene expression by recognizing and binding to specific DNA sequences, involving the dynamic alterations of chromatin structure and the formation of a complex with different kinds of cofactors, like DNA/histone modifying-enzymes, chromatin remodeling factors, and cell cycle factors. Despite the significance of transcription factors, it remains unclear to determine how these cofactors are regulated to cooperate with transcription factors, especially DNA/histone modifying-enzymes. It has been known that DNA/histone modifying-enzymes are regulated by post-translational modifications. And the most common and important modification is phosphorylation. Even though various DNA/histone modifying-enzymes have been classified and partly explained how phosphorylated sites of these enzymes function characteristically in recent studies. It still needs to find out the relationship between phosphorylation of these enzymes and the diseases-associated transcriptional regulation. Here this review describes how phosphorylation affects the transcription activity of these enzymes and other functions, including protein stability, subcellular localization, binding to chromatin, and interaction with other proteins.

Epstein-Barr Virus-Encoded MicroRNA-BART18-3p Promotes Colorectal Cancer Progression by Targeting De Novo Lipogenesis

The Epstein-Barr virus (EBV) genome encodes a cluster of 22 viral microRNAs, called miR-BamHI-A rightward transcripts (miR-BARTs), which are shown to promote the development of cancer. Here, this study reports that EBV-miR-BART18-3p is highly expressed in colorectal cancer (CRC) and is closely associated with the pathological and advanced clinical stages of CRC. Ectopic expression of EBV-miR-BART18-3p leads to increased migration and invasion capacities of CRC cells in vitro and causes tumor metastasis in vivo. Mechanistically, EBV-miR-BART18-3p activates the hypoxia inducible factor 1 subunit alpha/lactate dehydrogenase A axis by targeting Sirtuin, which promotes lactate accumulation and acetyl-CoA production in CRC cells under hypoxic condition. Increased acetyl-CoA utilization subsequently leads to histone acetylation of fatty acid synthase and fatty acid synthase-dependent fat synthesis, which in turn drives de novo lipogenesis. The oncogenic role of EBV-miR-BART18-3p is confirmed in the patient-derived tumor xenograft mouse model. Altogether, the findings define a novel mechanism of EBV-miR-BART18-3p in CRC development through the lipogenesis pathway and provide a potential clinical intervention target for CRC.

Insights into Regulators of p53 Acetylation

The tumor suppressor p53 is a transcription factor that regulates the expression of dozens of target genes and diverse physiological processes. To precisely regulate the p53 network, p53 undergoes various post-translational modifications and alters the selectivity of target genes. Acetylation plays an essential role in cell fate determination through the activation of p53. Although the acetylation of p53 has been examined, the underlying regulatory mechanisms remain unclear and, thus, have attracted the interest of researchers. We herein discuss the role of acetylation in the p53 pathway, with a focus on p53 acetyltransferases and deacetylases. We also review recent findings on the regulators of these enzymes to understand the mode of p53 acetylation from a broader perspective.

The Four Homeostasis Knights: In Balance upon Post-Translational Modifications

A cancer outcome is a multifactorial event that comes from both exogenous injuries and an endogenous predisposing background. The healthy state is guaranteed by the fine-tuning of genes controlling cell proliferation, differentiation, and development, whose alteration induces cellular behavioral changes finally leading to cancer. The function of proteins in cells and tissues is controlled at both the transcriptional and translational level, and the mechanism allowing them to carry out their functions is not only a matter of level. A major challenge to the cell is to guarantee that proteins are made, folded, assembled and delivered to function properly, like and even more than other proteins when referring to oncogenes and onco-suppressors products. Over genetic, epigenetic, transcriptional, and translational control, protein synthesis depends on additional steps of regulation. Post-translational modifications are reversible and dynamic processes that allow the cell to rapidly modulate protein amounts and function. Among them, ubiquitination and ubiquitin-like modifications modulate the stability and control the activity of most of the proteins that manage cell cycle, immune responses, apoptosis, and senescence. The crosstalk between ubiquitination and ubiquitin-like modifications and post-translational modifications is a keystone to quickly update the activation state of many proteins responsible for the orchestration of cell metabolism. In this light, the correct activity of post-translational machinery is essential to prevent the development of cancer. Here we summarize the main post-translational modifications engaged in controlling the activity of the principal oncogenes and tumor suppressors genes involved in the development of most human cancers.

2-month ketogenic diet preferentially alters skeletal muscle and augments cognitive function in middle aged female mice

The effect of a ketogenic diet (KD) on middle aged female mice is poorly understood as most of this work have been conducted in young female mice or diseased models. We have previously shown that an isocaloric KD started at middle age in male mice results in enhanced mitochondrial mass and function after 2 months on diet and improved cognitive behavior after being on diet for 14 months when compared with their control diet (CD) fed counterparts. Here, we aimed to investigate the effect of an isocaloric 2-month KD or CD on healthy 14-month-old female mice. At 16 months of age cognitive behavior tests were performed and then serum, skeletal muscle, cortex, and hippocampal tissues were collected for biochemical analysis. Two months on a KD resulted in enhanced cognitive behavior associated with anxiety, memory, and willingness to explore. The improved neurocognitive function was associated with increased PGC1α protein in the gastrocnemius (GTN) muscle and nuclear fraction. The KD resulted in a tissue specific increase in mitochondrial mass and kynurenine aminotransferase (KAT) levels in the GTN and soleus muscles, with a corresponding decrease in kynurenine and increase in kynurenic acid levels in serum. With KAT proteins being responsible for converting kynurenine into kynurenic acid, which is unable to cross the blood brain barrier and be turned into quinolinic acid-a potent neurotoxin, this study provides a potential mechanism of crosstalk between muscle and brain in mice on a KD that may contribute to improved cognitive function in middle-aged female mice.

Targeting the acetylation signaling pathway in cancer therapy

Acetylation represents one of the major post-translational protein modifications, which introduces an acetyl functional group into amino acids such as the lysine residue to yield an acetate ester bond, neutralizing its positive charge. Regulation of protein functions by acetylation occurs in multiple ways, such as affecting protein stability, activity, localization, and interaction with other proteins or DNA. It has been well documented that the recruitment of histone acetyltransferases (HATs) and histone deacetylases (HDACs) to the transcriptional machinery can modulate histone acetylation status, which is directly involved in the dynamic regulation of genes controlling cell proliferation and division. Dysregulation of gene expression is involved in tumorigenesis and aberrant activation of histone deacetylases has been reported in several types of cancer. Moreover, there is growing body of evidence showing that acetylation is widely involved in non-histone proteins to impact their roles in various cellular processes including tumorigenesis. As such, small molecular compounds inhibiting HAT or HDAC enzymatic activities have been developed and investigated for therapeutic purpose. Here we review the recent progress in our understanding of protein acetylation and discuss the therapeutic potential of targeting the acetylation signaling pathway in cancer.

Metabolite-derived protein modifications modulating oncogenic signaling

Malignant growth is defined by multiple aberrant cellular features, including metabolic rewiring, inactivation of tumor suppressors and the activation of oncogenes. Even though these features have been described as separate hallmarks, many studies have shown an extensive mutual regulatory relationship amongst them. On one hand, the change in expression or activity of tumor suppressors and oncogenes has extensive direct and indirect effects on cellular metabolism, activating metabolic pathways required for malignant growth. On the other hand, the tumor microenvironment and tumor intrinsic metabolic alterations result in changes in intracellular metabolite levels, which directly modulate the protein modification of oncogenes and tumor suppressors at both epigenetic and post-translational levels. In this mini-review, we summarize the crosstalk between tumor suppressors/oncogenes and metabolism-induced protein modifications at both levels and explore the impact of metabolic (micro)environments in shaping these.

The role of p53 in the alternation of vascular functions

Ageing is a risk factor for many degenerative diseases. Cardiovascular diseases (CVDs) are usually big burdens for elderly, caregivers and the health system. During the aging process, normal functions of vascular cells and tissue progressively lost and eventually develop vascular diseases. Endothelial dysfunction, reduced bioavailability of endothelium-derived nitric oxide are usual phenomena observed in patients with cardiovascular diseases. Myriad of studies have been done to investigate to delay the vascular dysfunction or improve the vascular function to prolong the aging process. Tumor suppressor gene p53, also a transcription factor, act as a gatekeeper to regulate a number of genes to maintain normal cell function including but not limited to cell proliferation, cell apoptosis. p53 also crosstalk with other key transcription factors like hypoxia-inducible factor 1 alpha that contribute to the progression of cardiovascular diseases. Therefore, in recent three decades, p53 has drawn scientists’ attention on its effects in vascular function. Though the role of tumor suppressor gene p53 is still not clear in vascular function, it is found to play regulatory roles and may involve in vascular remodeling, atherosclerosis or pulmonary hypertension. p53 may have a divergent role in endothelial and vascular muscle cells in those conditions. In this review, we describe the different effects of p53 in cardiovascular physiology. Further studies on the effects of endothelial cell-specific p53 deficiency on atherosclerotic plaque formation in common animal models are required before the therapeutic potential can be realized.