FUBP1 and FUBP2 enforce distinct epigenetic setpoints for MYC expression in primary single murine cells

FUBP1 in human cancer: Characteristics, functions, and potential applications

Far upstream element-binding protein 1 (FUBP1) is a single-stranded nucleic acid-binding protein that binds to the Far Upstream Element (FUSE) sequence and is involved in important biological processes, including DNA transcription, RNA biogenesis, and translation. Recent studies have highlighted the significance of aberrant expression or mutations in FUBP1 in the development of various tumors, with FUBP1 overexpression often indicating oncogenic roles in different tumor types. However, it is worth noting that recent research has discovered its tumor-suppressive role in cancer, which is not yet fully understood and appears to be tissue- or context-dependent. This review summarizes the association between FUBP1 and diverse cancers and discusses the functions of FUBP1 in cancer. In addition, this review proposes potential clinical implications and outlines future research directions to pave the way for the development of targeted therapeutic strategies focusing on FUBP1.

Far upstream element-binding protein 1 confers lobaplatin resistance by transcriptionally activating PTGES and facilitating the arachidonic acid metabolic pathway in osteosarcoma

Drug resistance is a major obstacle in cancer treatment and recurrence prevention and leads to poor outcomes in patients suffering from osteosarcoma. Clarification of the mechanism of drug resistance and exploration of effective strategies to overcome this obstacle could lead to clinical benefits for these patients. The expression of far upstream element-binding protein 1 (FUBP1) was found to be markedly elevated in osteosarcoma cell lines and clinical specimens compared with osteoblast cells and normal bone specimens. High expression of FUBP1 was correlated with a more aggressive phenotype and a poor prognosis in osteosarcoma patients. We found that overexpression of FUBP1 confers lobaplatin resistance, whereas the inhibition of FUBP1 sensitizes osteosarcoma cells to lobaplatin-induced cytotoxicity both in vivo and in vitro. Chromatin immunoprecipitation-seq and RNA-seq were performed to explore the potential mechanism. It was revealed that FUBP1 could regulate the transcription of prostaglandin E synthase (PTGES) and subsequently activate the arachidonic acid (AA) metabolic pathway, which leads to resistance to lobaplatin. Our investigation provides evidence that FUBP1 is a potential therapeutic target for osteosarcoma patients. Targeting FUBP1, its downstream target PTGES and the AA metabolic pathway may be promising strategies for sensitizing chemoresistant osteosarcoma cells to lobaplatin.

MYC: a complex problem

The MYC protooncogene functions as a universal amplifier of transcription through interaction with numerous factors and complexes that regulate almost every cellular process. However, a comprehensive model that explains MYC's actions and the interplay governing the complicated dynamics of components of the transcription and replication machinery is still lacking. Here, we review the potency of MYC as an oncogenic driver and how it regulates the broad spectrum of complexes (effectors and regulators). We propose a 'hand-over model' for differential partitioning and trafficking of unstructured MYC via a loose interaction network between various gene-regulatory complexes and factors. Additionally, the article discusses how unstructured-MYC energetically favors efficient modulation of the energy landscape of the transcription cycle.

Psi promotes Drosophila wing growth via direct transcriptional activation of cell cycle targets and repression of growth inhibitors

The first characterised FUSE Binding Protein family member, FUBP1, binds single-stranded DNA to activate MYC transcription. Psi, the sole FUBP protein in Drosophila, binds RNA to regulate P-element and mRNA splicing. Our previous work revealed pro-growth functions for Psi, which depend, in part, on transcriptional activation of Myc. Genome-wide functions for FUBP family proteins in transcriptional control remain obscure. Here, through the first genome-wide binding and expression profiles obtained for a FUBP family protein, we demonstrate that, in addition to being required to activate Myc to promote cell growth, Psi also directly binds and activates stg to couple growth and cell division. Thus, Psi knockdown results in reduced cell division in the wing imaginal disc. In addition to activating these pro-proliferative targets, Psi directly represses transcription of the growth inhibitor tolkin (tok, a metallopeptidase implicated in TGFβ signalling). We further demonstrate tok overexpression inhibits proliferation, while tok loss of function increases mitosis alone and suppresses impaired cell division caused by Psi knockdown. Thus, Psi orchestrates growth through concurrent transcriptional activation of the pro-proliferative genes Myc and stg, in combination with repression of the growth inhibitor tok.

Extracellular 5'-methylthioadenosine inhibits intracellular symmetric dimethylarginine protein methylation of FUSE-element binding proteins

Methylthioadenosine phosphorylase (MTAP) is a key enzyme in the methionine salvage pathway that converts the polyamine synthesis byproduct 5'-deoxy-5'-methylthioadenosine (MTA) into methionine. Inactivation of MTAP, often by homozygous deletion, is found in both solid and hematologic malignancies and is one of the most frequently observed genetic alterations in human cancer. Previous work established that MTAP-deleted cells accumulate MTA and contain decreased amounts of proteins with arginine residues symmetrically dimethylated (sDMA). These findings led to the hypothesis that accumulation of intracellular MTA inhibits the arginine protein methylase (PRMT5) responsible for bulk protein sDMAylation. Here, we confirm that MTAP-deleted cells have increased MTA accumulation and reduced protein sDMAylation. However, we also show that addition of extracellular MTA can cause a dramatic reduction of the steady-state levels of sDMA-containing proteins in MTAP+ cells, even though no sustained increase in intracellular MTA is found due to catabolism of MTA by MTAP. We determined that inhibition of protein sDMAylation by extracellular MTA occurs within 48 hours, is reversible, and is specific. In addition, we have identified two enhancer-binding proteins, FUBP1 and FUBP3, that are differentially sDMAylated in response to MTAP and MTA. These proteins work via the far upstream element (FUSE)-site located upstream of Myc and other promoters. Using a transcription reporter construct containing the FUSE-site, we demonstrate that MTA addition can reduce transcription, suggesting the reduction in FUBP1 and FUBP3 sDMAylation has functional consequences. Overall, our findings show that extracellular MTA can inhibit protein sDMAylation and that this inhibition can affect FUBP function.

Classification of adult-type diffuse gliomas: Impact of the World Health Organization 2021 update

Over the last decade, developments in molecular profiling have radically altered the diagnosis, classification, and management of numerous cancer types, with primary brain tumors being no exception. Although historically brain tumors have been classified based on their morphological characteristics, recent advances have allowed refinement of tumor classification based on molecular alterations. This shift toward molecular classification of primary brain tumors is reflected in the 2021 5^th edition of the WHO classification of central nervous system tumors (WHO 2021). In this review, we will discuss the most recent updates to the classification of adult‐type diffuse gliomas, a group of highly infiltrative and largely incurable CNS malignancies. It is our hope continued that refinement of molecular criteria will improve diagnosis, prognostication, and eventually treatment of these devastating tumors.

Pan-Cancer Transcriptome and Immune Infiltration Analyses Reveal the Oncogenic Role of Far Upstream Element-Binding Protein 1 (FUBP1)

Despite increasing evidence to support the relationship between FUBP1 and tumorigenesis in some types of cancers, there have been no analyses from a pan-cancer perspective. Here, we are the first to investigate the putative oncogenic role of FUBP1 in 33 cancer types based on The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Dysregulated FUBP1 expression was observed in most cancer types, and high FUBP1 expression suggests poor prognosis in cancers such as ACC, KICH, LIHC, LUAD, LUSC, SARC, CESC, and SKCM. Missense mutation is the most common type of FUBP1 mutation, and R430 in KH_4 is a predominant mutation site. Enhanced phosphorylation of FUBP1 at the S120 site has been observed in clear cell RCC, lung adenocarcinoma, and pediatric brain cancer specimens from African-American and Asian individuals. The expression of FUBP1 was found to be negatively correlated with the infiltration of CD8+ T lymphocytes in GBM, HNSC-HPV- and UCEC but positively correlated with that of tumor-associated fibroblasts in CESC, ESCA, HNSC, LIHC, LUAD, PAAD, and THYM. Furthermore, RNA splicing and spliceosome signaling were predominantly enriched in both GO and KEGG analyses of the functional mechanism of FUBP1. Briefly, this pan-cancer analysis comprehensively revealed the multifaceted characteristics and oncogenic role of FUBP1 in different human cancers.

The Simple Biology of Flipons and Condensates Enhances the Evolution of Complexity

The classical genetic code maps nucleotide triplets to amino acids. The associated sequence composition is complex, representing many elaborations during evolution of form and function. Other genomic elements code for the expression and processing of RNA transcripts. However, over 50% of the human genome consists of widely dispersed repetitive sequences. Among these are simple sequence repeats (SSRs), representing a class of flipons, that under physiological conditions, form alternative nucleic acid conformations such as Z-DNA, G4 quartets, I-motifs, and triplexes. Proteins that bind in a structure-specific manner enable the seeding of condensates with the potential to regulate a wide range of biological processes. SSRs also encode the low complexity peptide repeats to patch condensates together, increasing the number of combinations possible. In situations where SSRs are transcribed, SSR-specific, single-stranded binding proteins may further impact condensate formation. Jointly, flipons and patches speed evolution by enhancing the functionality of condensates. Here, the focus is on the selection of SSR flipons and peptide patches that solve for survival under a wide range of environmental contexts, generating complexity with simple parts.