Biology subjects

Gonzalez-Prieto, R.

Publications and source records attributed to Gonzalez-Prieto, R..

11 recordsLinked to original sources

bioRxiv2026

BCLAF1 links RNA splicing to ATF4-dependent metabolic adaptation in acute myeloid leukemia

Acute myeloid leukemia (AML) is driven by a combination of genetic alterations and non-mutational mechanisms that disrupt normal hematopoiesis and support leukemic cell survival. While the mutational landscape of AML is well characterized, the non-genetic processes that sustain leukemic maintenance remain comparatively less understood. Using human AML cell lines and murine models of AML, we identify BCL2-associated transcription factor 1 (BCLAF1) as a key regulator of leukemic progression through control of mRNA processing. BCLAF1 physically associates with core spliceosome components and regulates alternative splicing, with a predominant effect on intron retention. We demonstrate that BCLAF1 is required for the productive splicing of activating transcription factor 4 (ATF4) mRNA, thereby sustaining ATF4 protein expression. Loss of BCLAF1 reduces ATF4 protein levels, leading to downregulation of metabolic target genes and disruption of de novo amino acid biosynthesis. Furthermore, depletion of BCLAF1 sensitizes AML cells to venetoclax, a clinically relevant BCL-2 inhibitor. Together, these findings uncover a previously unrecognized role for BCLAF1 in coordinating mRNA splicing and metabolic adaptation in AML, highlighting its potential as a therapeutic target. Statement of significanceAberrant RNA splicing and metabolic reprogramming are hallmarks of cancer, yet how these processes are mechanistically linked remains unclear. This study identifies BCLAF1 as a key regulator connecting splicing control to amino acid metabolism in acute myeloid leukemia, revealing a previously unrecognized functional vulnerability at the intersection of these pathways.

cancer biology↗

bioRxiv2026

DNA end-resection is stimulated by an interaction between BRCA1 exon 11 and TOPBP1

Approximately 60% of the tumour suppressor protein BRCA1 is encoded by a single exon. Many tumours carry mutations in this exon, often resulting in exon skipping and thus a protein of a severely reduced size. Although none of the well-described protein domains of BRCA1 are encoded by this exon 11, the isoform lacking this part shows a hypomorphic activity in homologous recombination. To better understand the function of this large exon, we performed proteomic analyses to identify interaction partners via this part of the protein. Here, we report a DNA damage-and phospho-dependent interaction of TOPBP1 to the protein region of BRCA1 encoded by exon 11. Mechanistically, this interaction is required for BRCA1s role in end-resection during homologous recombination. In contrast, the interaction is not required for TOPBP1s role in ATR activation. Our data provide novel mechanistic insight into the function of this poorly characterized part of the BRCA1 protein.

molecular biology↗

bioRxiv2025

miRNA-mediated cell-to-cell communications boost DNA repair during theRadioadaptative Response

The Radioadaptive Response (RAR) is a phenomenon where a low, or priming, dose of ionizing radiation enhances cellular resistance to subsequent higher doses. We investigated whether RAR involves alterations in Homologous Recombination (HR), a high-fidelity DNA repair pathway. Using fibroblast models, we found that primed cells exhibit accelerated DNA end resection, an initial and essential HR step. This effect is mostly mediated by a bystander mechanism involving small extracellular vesicles (sEVs), as conditioned media fully replicated it. RNA profiling of sEVs identified miR-126-3p and miR-451a as key regulators of this response. Significantly, inhibiting miR-451a induced RAR in normally unresponsive cells. We further identified a miR-451a-p38-CCAR2 axis that enhances HR through suppression of CCAR2. These findings delineate a novel miRNA-mediated, sEV-driven mechanism that regulates HR during RAR, with potential therapeutic implications. Significance StatementWe uncover a previously unrecognized mechanism by which human fibroblasts enhance DNA double-strand break repair through homologous recombination following a priming dose of ionizing radiation-a phenomenon known as the radioadaptive response (RAR). We demonstrate that this enhanced repair capacity is driven by small extracellular vesicle (sEV)-mediated intercellular communication, through a transient reprograming of the DNA repair capacity of neighboring cells by modulating the levels of two key microRNAs. These provide new clues on how extracellular RNA signaling governs genome maintenance, with significant implications for genome stability in healthy and pathological context. The identification of actionable modulators further strengthens the translational potential of our work.

molecular biology↗

bioRxiv2024

SUMOylation differentially regulates SMCHD1 complex formation and function in a genomic context-specific manner

Structural Maintenance of Chromosomes Hinge Domain Containing 1 (SMCHD1) is a chromatin repressor regulating gene expression and chromatin architecture of distinct autosomal and X-chromosomal loci. SMCHD1 mutations cause derepression of the D4Z4 macrosatellite repeat-embedded DUX4 gene in skeletal muscle of facioscapulohumeral muscular dystrophy (FSHD) patients Little is known about the regulation and post-translational modification of SMCHD1. Here we report the SUMOylation dynamics of SMCHD1 and its impact on autosomal single copy and repetitive loci, and the inactive X chromosome (Xi). We identify that SMCHD1 is SUMOylated primarily at lysine 1374, uncover factors regulating SMCHD1 SUMOylation, and demonstrate that SMCHD1 interacts with chromatin repressors TRIM28, HNRNPK and SETDB1 in a SUMO-dependent manner. We find that SUMOylation impacts Xi engagement of SMCHD1, maintenance of a repressive D4Z4 chromatin structure preventing DUX4 expression, and regulation of LRIF1 promoter activity. The rapid, SUMO-dependent upregulation of DUX4 could explain the bursts of DUX4 expression typical for FSHD muscle.

molecular biology↗

bioRxiv2023

BRCA1/BARD1 ubiquitinates PCNA in unperturbed conditions to promote replication fork stability and continuous DNA synthesis.

Deficiencies in the BRCA1 tumor suppressor gene are the main cause of hereditary breast and ovarian cancer. BRCA1 is involved in the Homologous Recombination DNA repair pathway, and, together with BARD1, forms a heterodimer with ubiquitin E3 activity. The relevance of the BRCA1/BARD1 ubiquitin E3 activity for tumor suppression and DNA repair remains controversial and most efforts aimed to identify BRCA1/BARD1 ubiquitination substrates rely on indirect evidence. Here, we observed that the BRCA1/BARD1 ubiquitin E3 activity was not required for Homologous Recombination or resistance to Olaparib. Using TULIP2 methodology, which enables the direct identification of E3-specific ubiquitination substrates, we identified substrates for BRCA1/BARD1. We found that PCNA is ubiquitinated by BRCA1/BARD1 in unperturbed conditions independently of RAD18. PCNA ubiquitination by BRCA1/BARD1 avoids the formation of ssDNA gaps during DNA replication and promotes replication fork stability epistatically to BRCA1 S114 phosphorylation, addressing the controversy about the function of BRCA1/BARD1 E3 activity in Homologous Recombination.

molecular biology↗

bioRxiv2022

SUMO Activated Target Traps (SATTs) enable the identification of a comprehensive E3-specific SUMO proteome.

Ubiquitin and ubiquitin-like conjugation cascades consist of dedicated E1, E2 and E3 enzymes with E3s providing substrate specificity. Mass spectrometry-based approaches have enabled the identification of more than 60,000 acceptor sites for ubiquitin and 40,000 acceptor sites for SUMO2/3. However, E3-to-target wiring is poorly understood. The limited number of SUMO E3s provides the unique opportunity to systematically study E3-substrate wiring. We developed SUMO Activated Target Traps (SATTs) and systematically identified substrates for eight different SUMO E3s, PIAS1, PIAS2, PIAS3, PIAS4, NSMCE2, ZNF451, LAZSUL(ZNF451-3) and ZMIZ2. SATTs enabled us to identify 590 SUMO1 and 1195 SUMO2/3 targets in an E3-specific manner. We found pronounced E3 substrate preference, even at the substrate isoform level. Quantitative proteomics enabled us to measure substrate specificity of E3s, quantified using the SATT index. Furthermore, we developed the Polar SATTs web-based tool (https://amsterdamstudygroup.shinyapps.io/PolaRVolcaNoseR/) to browse the dataset in an interactive manner, increasing the accessibility of this resource for the community. Overall, we uncover E3-to-target wiring of 1681 SUMO substrates, highlighting unique and overlapping sets of substrates for eight different SUMO E3 ligases.

molecular biology↗

bioRxiv2022

UBC9 and EME1 sumoylation foster ribosomal DNA damage repair in CPT response

UBC9 sumoylation (S*UBC9) in mammals contributes to SUMO target discrimination, biochemically1. Here, we present biological insights by characterizing a sumoylation mimetic UBC9-fusion (mCS~UBC9) in comparison to its wild-type (mCUBC9). We observe that sumoylation promotes UBC9s stability, nuclear localization and is beneficial for cell survival. We identified EME1, the regulatory subunit of the structure-specific endonuclease EME1-MUS81, as S*UBC9 substrate and demonstrate EME1 and UBC9 sumoylation being advantageous for survival upon Camptothecin (CPT) exposure. Moreover, mCS~UBC9 expression enhances double-strand breaks (DSBs) and replication upon CPT treatment, features assigned to the EME1-MUS81 complex2. EME1 and mCS~UBC9 co-localize in nucleolar repair-condensates, that enlarge and round when exposed to the drug. Together, these findings imply that S*UBC9-induced EME1 sumoylation improves ribosomal rDNA repair, which might prevent dangerous second template switches in highly repetitive ribosomal chromatin and allow the converging replication fork to complete DNA replication. Finally, we discuss implications of these findings for anti-cancer therapy.

molecular biology↗

bioRxiv2022

Multi-level monitoring of EME1-MUS81 in CPT induced nucleolar rDNA repair

We identified EME1, the regulatory subunit of the structure-specific endonuclease complex EME1-MUS81, as substrate for the sumoylated UBC9 and demonstrated synergistic functions in promoting Camptothecin (CPT)-induced nucleolar ribosomal DNA (rDNA) repair (Nagamalleswari et al, co-submitted). Sumoylation of EME1 appears complex involving mono- and poly-sumoylation. Hence, we addressed here whether these modifications differentially regulate EME1 functions by analyzing EME1-variant expressing cell lines including mono-sumo(1)ylation and poly-sumo(2)ylation mimetic fusions. We complemented our analysis with the regulated endogenous EME1 interactome and our observation that Trichostatin A (TSA) induced EME1 and UBC9 sumoylation. Our findings are substantiated by identifying several regulatory proteins and by detecting CPT-induced endogenous di- and poly-sumoylated EME1 in different cell fractions. Together, our data suggest that Histone H4 acetylation, two mono-sumoylation events, poly-sumoylation, ISG15 and ubiquitination sequentially and in mutual dependence tightly control the intracellular localization, recruitment to DNA lesions, enzymatic activity, withdrawal from DNA lesions and the stability of EME1.

molecular biology↗

bioRxiv2021

Unbiased in vivo exploration of nuclear bodies-enhanced sumoylation reveals that PML orchestrates embryonic stem cell fate

Membrane-less organelles are condensates formed by phase separation whose functions often remain enigmatic. Upon oxidative stress, PML scaffolds Nuclear Bodies (NBs) to regulate senescence or metabolic adaptation, but their role in pluripotency remains elusive. Here we establish that PML is required for basal SUMO2/3 conjugation in mESCs and oxidative stress-driven sumoylation in mESCs or in vivo. PML NBs create an oxidation-protective environment for UBC9-driven SUMO2/3 conjugation of PML partners, often followed by their poly-ubiquitination and degradation. Differential in vivo proteomics identified several members of the KAP1 complex as PML NB-dependent SUMO2-targets. The latter drives functional activation of this key epigenetic repressor. Accordingly, Pml-/- mESCs re-express transposable elements and display features of totipotent-like cells, a process further enforced by PML-controlled SUMO2-conjugation of DPPA2. Finally, PML is required for adaptive stress responses in mESCs. Collectively, PML orchestrates mESC fate through SUMO2-conjugation of key transcriptional or epigenetic regulators, raising new mechanistic hypotheses about PML roles in normal or cancer stem cells.

cell biology↗

bioRxiv2020

A CSB-PAF1C axis restores processive transcription elongation after DNA damage repair

The coordinated transcription of genes involves the regulated release of RNA polymerase II (RNAPII) from promoter-proximal sites into active elongation. DNA lesions in transcribed strands block elongation and induce a strong transcriptional arrest. The transcription-coupled repair (TCR) pathway efficiently removes transcription-blocking DNA lesions, but this is not sufficient to resume transcription. Through proteomics screens, we find that the TCR-specific CSB protein loads the evolutionary conserved PAF1 complex (PAF1C) onto RNAPII in promoter-proximal regions in response to DNA damage. PAF1C is dispensable for TCR-mediated repair, but is essential for recovery of RNA synthesis after UV irradiation, suggesting an uncoupling between DNA repair and transcription recovery. Moreover, we find that PAF1C promotes RNAPII pause release in promoter-proximal regions and subsequently acts as a processivity factor that stimulates transcription elongation throughout genes. Our findings expose the molecular basis for a non-canonical PAF1C-dependent pathway that restores transcription throughout the human genome after genotoxic stress.

cell biology↗

bioRxiv2019

The sequential and cooperative action of CSB, CSA and UVSSA targets the TFIIH complex to DNA damage-stalled RNA polymerase II

The response to DNA damage-stalled RNA polymerase II (RNAPIIo) involves the assembly of the transcription-coupled repair (TCR) complex on actively transcribed strands. The function of the TCR proteins CSB, CSA and UVSSA and the manner in which the core DNA repair complex, including transcription factor IIH (TFIIH), is recruited are largely unknown. Here, we define the assembly mechanism of the TCR complex in human isogenic knockout cells. We show that TCR is initiated by RNAPIIo-bound CSB, which recruits CSA through a newly identified CSA-interaction motif (CIM). Once recruited, CSA facilitates the association of UVSSA with stalled RNAPIIo. Importantly, we find that UVSSA is the key factor that recruits the TFIIH complex in a manner that is stimulated by CSB and CSA. Together these findings reveal a sequential and highly cooperative assembly mechanism of TCR proteins and reveal the mechanism for TFIIH recruitment to DNA damage-stalled RNAPIIo to initiate repair.

molecular biology↗