Biology subjects

Smogorzewska, A.

Publications and source records attributed to Smogorzewska, A..

12 recordsLinked to original sources

bioRxiv2025

Genotoxic formaldehyde and lipid aldehydes are sources of DNA damage in keratinocytes

The Fanconi anemia (FA) pathway is vital for the repair of DNA interstrand crosslinks (ICLs), which are caused by a variety of endogenous and exogenous genotoxins including reactive aldehydes. Patients with pathogenic variants in the FA pathway are predisposed to early-onset, aggressive malignancies, especially leukemia and head and neck, esophageal, and anogenital squamous cell carcinomas (SCCs). Prior studies have linked endogenous formaldehyde and acetaldehyde in hematopoietic stem cells with bone marrow failure and leukemia in FA-deficient mice. However, the genotoxic aldehydes specific to mucosal keratinocytes, precursors of FA-associated SCCs, remain to be identified. Here, to identify alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs) necessary for protection of keratinocyte genomes from endogenous metabolites, we used a sensitized background of FA-pathway deficiency. We systematically inactivated all highly expressed ADH and ALDHs genes in FANCA-deficient keratinocyte cell lines and identified genes required for their survival. We report that loss of ADH5 or ALDH3-family enzymes in FA pathway-deficient cells has a synthetic lethal effect and induces DNA damage markers, nominating these genes as important defense mechanisms in the detoxification of endogenous aldehydes and prevention of carcinogenesis in keratinocytes. Loss of ADH5 increases formaldehyde levels, while simultaneous loss of four functionally redundant ALDH3 isozymes is predicted to cause accumulation of lipid aldehydes. FA-deficient keratinocytes are more sensitive to treatment with formaldehyde and the lipid aldehyde 4-hydroxynonenal (4HNE) compared to FA-competent cells. In addition, the thiol-rich antioxidant N-acetyl-L-cysteine (NAC) partially rescued the growth of FANCA-/- ADH5-/- cells and lowered the level of endogenous DNA damage. This work identifies important defense mechanisms in keratinocytes and suggests cancer preventive strategies in patients with Fanconi anemia. SignificanceThis work shows that ADH5 and ALDH3-family enzymes function as tier 1 defense mechanisms against endogenous DNA-damaging metabolites in keratinocytes. Enhanced detoxification of endogenous aldehydes might prevent DNA damage and mutagenesis, which drive Fanconi anemia-associated head and neck and other mucosal squamous cell carcinomas.

cell biology↗

bioRxiv2025

Proteome-wide in silico screening for human protein-protein interactions

Protein-protein interactions (PPIs) drive virtually all biological processes, yet most PPIs have not been identified and even more remain structurally unresolved. We developed a two-step computational screen for human PPIs. First, a classifier called KIRC (Knowledge-Informed Rapid Classifier), trained on biological features, was used to rank all 200 million possible protein pairs in the human proteome by their interaction likelihood. Second, the [~]1.6 million top-ranked KIRC pairs were subjected to structure prediction by AlphaFold-Multimer and ranked using SPOC (Structure Prediction and Omics Classifier), which identifies functional predictions based on biological and structural features. This pipeline revealed 16,000 high-confidence PPIs ([~]90% precision), of which more than 5,000 were not previously recognized and more than 12,000 have not been structurally resolved. We use this "predictome" to formulate new hypotheses in different areas of biology, reinterpret low-resolution cryo-EM maps, and identify and validate novel PPIs that may support replication-coupled chromatin assembly. The predicted PPIs, viewable at predictomes.org, are expected to accelerate characterization of the molecular interactions that underlie vertebrate cell physiology.

bioinformatics↗

bioRxiv2024

G-quadruplexes are a source of vulnerability in BRCA2 deficient granule cell progenitors and medulloblastoma

Biallelic pathogenic variants in the essential DNA repair gene BRCA2 causes Fanconi anemia, complementation group FA-D1. Patients in this group are highly prone to develop embryonal tumors, most commonly medulloblastoma arising from the cerebellar granule cell progenitors (GCPs). GCPs undergo high proliferation in the postnatal cerebellum under SHH activation, but the type of DNA lesions that require the function of the BRCA2 to prevent tumorigenesis remains unknown. To identify such lesions, we assessed both GCP neurodevelopment and tumor formation using a mouse model with deletion of exons three and four of Brca2 in the central nervous system, coupled with global Trp53 loss. Brca2{Delta}ex3-4;Trp53-/- animals developed SHH subgroup medulloblastomas with complete penetrance. Whole-genome sequencing of the tumors identified structural variants with breakpoints enriched in areas overlapping G-quadruplexes (G4s). Brca2-deficient GCPs exhibited decreased replication speed in the presence of the G4-stabilizer pyridostatin. Pif1 helicase, which resolves G4s during replication, was highly upregulated in tumors, and Pif1 knockout in primary MB tumor cells resulted in increased genome instability upon pyridostatin treatment. These data suggest that G4s may represent sites prone to replication stalling in highly proliferative GCPs and without BRCA2, G4s become a source of genome instability. Tumor cells upregulate G4-resolving helicases to facilitate rapid proliferation through G4s highlighting PIF1 helicase as a potential therapeutic target for treatment of BRCA2-deficient medulloblastomas.

cancer biology↗

bioRxiv2023

RTF2 controls replication repriming and ribonucleotide excision at the replisome

Genetic information is duplicated via the highly regulated process of DNA replication. The machinery coordinating this process, the replisome, encounters many challenges, including replication fork-stalling lesions that threaten the accurate and timely transmission of genetic information. Cells have multiple mechanisms to repair or bypass lesions that would otherwise compromise DNA replication1,2. We have previously shown that proteasome shuttle proteins, DNA Damage Inducible 1 and 2 (DDI1/2) function to regulate Replication Termination Factor 2 (RTF2) at the stalled replisome, allowing for replication fork stabilization and restart3. Here we show that RTF2 regulates replisome localization of RNase H2, a heterotrimeric enzyme responsible for removing RNA in the context of RNA-DNA heteroduplexes4-6. We show that during unperturbed DNA replication, RTF2, like RNase H2, is required to maintain normal replication fork speeds. However, persistent RTF2 and RNase H2 at stalled replication forks compromises the replication stress response, preventing efficient replication restart. Such restart is dependent on PRIM1, the primase component of DNA polymerase -primase. Our data show a fundamental need for regulation of replication-coupled ribonucleotide incorporation during normal replication and the replication stress response that is achieved through RTF2. We also provide evidence for PRIM1 function in direct replication restart following replication stress in mammalian cells.

molecular biology↗

bioRxiv2022

Fanconi anemia-isogenic head and neck cancer cell line pairs - a basic and translational science resource

Fanconi anemia (FA) is a heritable malformation, bone marrow failure and cancer predisposition syndrome that confers an exceptionally high risk of developing carcinomas arising in squamous mucosal epithelia lining the mouth, proximal esophagus, vulva and anus. The origin of these cancers is not understood, and no effective way has been identified to prevent or delay their appearance. FA-associated carcinomas are also therapeutically challenging, as they may be multi-focal and stage-advanced at diagnosis making surgical control challenging. Moreover, individuals with FA have systemic DNA damage hypersensitivity and thus an elevated risk of toxicity when treated with standard-of-care therapies such as DNA cross-linking drugs and ionizing radiation. We developed the Fanconi Anemia Cancer Cell Line Resource (FA-CCLR) in order to foster new research on the origins, treatment, and prevention of FA-associated cancers. The FA-CCLR consists of FANC-isogenic head and neck squamous cell carcinoma (HNSCC) cell line pairs from cancers arising in individuals with FA, or newly engineered from sporadic HNSCC cell lines. Molecular, cellular, and biochemical analyses were used to demonstrate the causal dependence of key FA-associated phenotypes on FANC genotype, expression and pathway activity. These FANC-isogenic cell line pairs are available to academic and non-profit investigators, with ordering information available at the Fanconi Anemia Research Materials Resource and Repository at Oregon Health & Sciences University, Portland OR. SignificanceWe have generated new isogenic cancer cell line models to investigate the origins, treatment and prevention of Fanconi anemia-associated squamous carcinomas that target the oral mucosa, proximal esophagus, and anogenital region.

cancer biology↗

bioRxiv2022

ALDH9A1 Deficiency as a Source of Endogenous DNA Damage that Requires Repair by the Fanconi Anemia Pathway

Fanconi anemia (FA) pathway is required for the repair of DNA interstrand crosslinks (ICL). ICLs are caused by genotoxins, such as chemotherapeutic agents or reactive aldehydes. Inappropriately repaired ICLs contribute to hematopoietic stem cell (HSC) failure and tumorigenesis. While endogenous acetaldehyde and formaldehyde are known to induce HSC failure and leukemia in humans with FA, the effects of other toxic metabolites in FA pathogenesis have not been systematically investigated. Using a metabolism-focused CRISPR screen, we found that ALDH9A1 deficiency causes synthetic lethality in FA pathway-deficient cells. Combined deficiency of ALDH9A1 and FANCD2 causes genomic instability, apoptosis, and decreased hematopoietic colony formation. Fanca-/-Aldh9a1-/- mice exhibited an increased incidence of ovarian tumors. A suppressor CRISPR screen revealed that the loss of ATP13A3, a polyamine transporter, resulted in improved survival of FANCD2-/-ALDH9A1-/- cells. These findings implicate high intracellular polyamines and the resulting 3-aminopropanal or acrolein in the pathogenesis of FA. In addition, we find that ALDH9A1 variants may be modifying disease onset in FA patients. Statement of SignificanceALDH9A1 deficiency is a previously unrecognized source of endogenous DNA damage. If not repaired by the Fanconi anemia pathway, such damage leads to increased genomic instability and tumorigenesis. Limiting substrates that accumulate when ALDH9A1 is absent can reduce aldehyde production and rescue synthetic lethality in the combined deficiency of ALDH9A1/FANCD2.

genetics↗

bioRxiv2021

Comprehensive analysis of DNA replication timing in genetic diseases and gene knockouts identifies MCM10 as a novel regulator of the replication program

Cellular proliferation depends on the accurate and timely replication of the genome. Several genetic diseases are caused by mutations in key DNA replication genes; however, it remains unclear whether these genes influence the normal program of DNA replication timing. Similarly, the factors that regulate DNA replication dynamics are poorly understood. To systematically identify trans-acting modulators of replication timing, we profiled replication in 184 cell lines from three cell types, encompassing 60 different gene knockouts or genetic diseases. Through a rigorous approach that considers the background variability of replication timing, we concluded that most samples displayed normal replication timing. However, mutations in two genes showed consistently abnormal replication timing. The first gene was RIF1, a known modulator of replication timing. The second was MCM10, a highly conserved member of the pre-replication complex. MCM10 mutant cells demonstrated replication timing variability comprising 46% of the genome and at different locations than RIF1 knockouts. Replication timing alterations in MCM10-mutant cells was predominantly comprised of replication initiation defects. Taken together, this study demonstrates the remarkable robustness of the human replication timing program and reveals MCM10 as a novel modulator of DNA replication timing.

genetics↗

bioRxiv2020

Transcriptional silencing of ALDH2 in acute myeloid leukemia confers a dependency on Fanconi anemia proteins

Hundreds of genes become aberrantly silenced in acute myeloid leukemia (AML), with most of these epigenetic changes being of unknown functional consequence. Here, we demonstrate how gene silencing can lead to an acquired dependency on the DNA repair machinery in AML. We make this observation by profiling the essentiality of the ubiquitin conjugation and ligation machinery in cancer cell lines using domain-focused CRISPR screening, which revealed Fanconi anemia (FA) proteins UBE2T (an E2) and FANCL (an E3) as unique dependencies in AML. We demonstrate that these dependencies are due to a synthetic lethal interaction between FA proteins and Aldehyde Dehydrogenase 2 (ALDH2), which function in parallel pathways to counteract the genotoxic effects of endogenous aldehydes. We provide evidence that DNA hypermethylation and transcriptional silencing of ALDH2 occur in a recurrent manner in human AML patient samples, which is sufficient to confer FA pathway dependency in this disease. Taken together, our study suggests that targeting of the ubiquitination reaction catalyzed by FA proteins can eliminate ALDH2-deficient AML.

cancer biology↗

bioRxiv2020

CENP-A chromatin prevents replication stress at centromeres to avoid structural aneuploidy

Chromosome segregation relies on centromeres, yet their repetitive DNA is often prone to aberrant rearrangements under pathological conditions. Factors that maintain centromere integrity to prevent centromere-associated chromosome translocations are unknown. Here, we demonstrate the importance of the centromere-specific histone H3 variant CENP-A in safeguarding DNA replication of alpha-satellite repeats to prevent structural aneuploidy. Rapid removal of CENP-A in S-phase, but not other cell cycle stages, caused accumulation of R-loops with increased centromeric transcripts, and interfered with replication fork progression. Replication without CENP-A causes recombination at alpha-satellites in an R-loop-dependent manner, unfinished replication and anaphase bridges. In turn, chromosome breakage and translocations arise specifically at centromeric regions. Our findings provide insights into how specialized centromeric chromatin maintains the integrity of transcribed noncoding repetitive DNA during S-phase. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=177 SRC="FIGDIR/small/277103v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@4e6dc4org.highwire.dtl.DTLVardef@1089c90org.highwire.dtl.DTLVardef@5ee5c2org.highwire.dtl.DTLVardef@3e300d_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2019

Distinct roles of BRCA2 in replication fork protection in response to hydroxyurea and DNA interstrand crosslinks

DNA interstrand crosslinks (ICLs) are a form of DNA damage that requires the interplay of a number of repair proteins including those of the Fanconi anemia (FA) and the homologous recombination (HR) pathways. Pathogenic variants in the essential gene BRCA2/FANCD1, when monoallelic, predispose to breast and ovarian cancer, and when biallelic, results in a severe subtype of Fanconi anemia. BRCA2 function in the FA pathway is attributed to its role as a mediator of the RAD51 recombinase in HR repair of the programmed DNA double strand breaks (DSB). BRCA2 and RAD51 functions are also required to protect stalled replication forks from nucleolytic degradation during response to hydroxyurea (HU). While RAD51 has been shown to be necessary in the early steps of ICL repair to prevent aberrant nuclease resection, the role of BRCA2 in this process has not been described. Here, based on the analysis of BRCA2 DNA binding domain (DBD) mutants discovered in FA patients presenting with atypical FA-like phenotypes, we establish that BRCA2 is necessary for protection of DNA at an ICL. Cells carrying DBD BRCA2 mutations are sensitive to ICL inducing agents but resistant to HU treatment consistent with relatively high HR repair in these cells. BRCA2 function at an ICL protects against DNA2-WRN nuclease-helicase complex and not the MRE11 nuclease implicated in the resection of HU-stalled replication forks. Our results also indicate that unlike the processing at HU-stalled forks, function of the SNF2 translocases (SMARCAL1, ZRANB3, or HLTF), implicated in fork reversal, are not an integral component of the ICL repair, pointing to a different mechanism of fork protection at different DNA lesions.

molecular biology↗

bioRxiv2019

Clinical severity in Fanconi anemia correlates with residual function of FANCB missense variants

Fanconi anemia (FA) is the most common genetic cause of bone marrow failure, and is caused by inherited pathogenic variants in any of 22 genes. Of these, only FANCB is X-linked. We describe a cohort of 19 children with FANCB variants, from 16 families of the International Fanconi Anemia Registry (IFAR). Those with FANCB deletion or truncation demonstrate earlier than average onset of bone marrow failure, and more severe congenital abnormalities compared to a large series of FA individuals in the published reports. This reflects the indispensable role of FANCB protein in the enzymatic activation of FANCD2 monoubiquitination, an essential step in the repair of DNA interstrand crosslinks. For FANCB missense variants, more variable severity is associated with the extent of residual FANCD2 monoubiquitination activity. We used transcript analysis, genetic complementation, and biochemical reconstitution of FANCD2 monoubiquitination to determine the pathogenicity of each variant. Aberrant splicing and transcript destabilization was associated with two missence variants. Individuals carrying missense variants with drastically reduced FANCD2 monoubiquitination in biochemical and/or cell-based assays showed earlier onset of hematologic disease and shorter survival. Conversely, variants with near-normal FANCD2 monoubiquitination were associated with more favorable outcome. Our study reveals a genotype-phenotype correlation within the FA-B complementation group of FA, where severity is linked to the extent of residual FANCD2 monoubiquitination.\n\nKEY POINTSO_LIX-linked FANCB pathogenic variants predominantly cause acute, early onset bone marrow failure and severe congenital abnormalities\nC_LIO_LIBiochemical and cell-based assays with patient variants reveal functional properties of FANCB that associate with clinical severity\nC_LI

molecular biology↗

bioRxiv2017

Suppression of non-homologous end joining does not rescue DNA repair defects in Fanconi anemia patient cells

Severe cellular sensitivity and aberrant chromosomal rearrangements in response to DNA interstrand crosslink (ICL) inducing agents are hallmarks of Fanconi anemia (FA) deficient cells. These phenotypes have previously been ascribed to inappropriate activity of non-homologous end joining (NHEJ) rather than a direct consequence of DNA ICL repair defects. Here we used chemical inhibitors, RNAi, and Clusterd Regularly Interspaced Short Palindromic Repeat (CRISPR)-Cas9 to inactivate various components of NHEJ in cells from FA patients. We show that suppression of DNA-PKcs, DNA Ligase IV and 53BP1 is not capable of rescuing ICL-induced proliferation defects and only 53BP1 knockout partially suppresses the chromosomal abnormalities of FA patient cells.

molecular biology↗