Biology subjects

Adamowicz, M.

Publications and source records attributed to Adamowicz, M..

5 recordsLinked to original sources

bioRxiv2026

DNA Polymerase beta Accelerates Cellular DNA Base Excision Repair by Suppressing Excessive PARP1 Engagement

DNA polymerase beta (POL{beta}) is required for rapid rates of cellular DNA base excision repair (BER). However, the reason for this requirement is unclear, because other DNA polymerases can replace POL{beta}, in vitro. Here, we have identified the essential role of POL{beta} during cellular BER. As expected, POL{beta} deletion in human RPE-1 cells resulted in the rapid accumulation of DNA strand break intermediates during incubation with the monofunctional alkylating agent, methyl methanesulphonate (MMS). However, this accumulation was not detected in cells that also lack PARP1, indicating that POL{beta} is required for BER only if PARP1 is present. This result is reminiscent of the essential role of XRCC1 during BER, which is to suppress the excessive engagement and activity of PARP1 at BER intermediates and thereby enable their access and repair by other enzymes. Indeed, we found that POL{beta} is required to prevent excessive PARP1 engagement and activity during BER, and that XRCC1 and POL{beta} fulfil this function together. Finally, similar to XRCC1, loss of POL{beta} leads to persistent transcriptional suppression during MMS-induced BER, and this suppression is alleviated by treatment with PARP inhibitor. In summary, we show here that the essential role of POL{beta} during cellular BER is to suppress excessive PARP1 engagement and activity, and thereby maintain rapid rates of this important DNA repair process.

molecular biology↗

bioRxiv2025

Plasma Cell-Free DNA in Acute and Chronic Aortic Syndromes.

Acute aortic syndromes and other acute aortic events are commonly misdiagnosed and associated with high mortality and morbidity. There is need for a blood-based biomarker to indicate the acutely unstable aorta. Plasma cell-free DNA (cfDNA) is an established diagnostic marker in prenatal testing and cancer. Its use as a potential diagnostic marker in aortic disease remains to be demonstrated. We found that plasma short-fragment (50-700bp) cfDNA concentration is significantly increased in patients with both acute and chronic aortic disease compared with several control groups, and is significantly increased in acute versus chronic aortic disease. Plasma sf-cfDNA may differentiate acute aortic syndromes from other acute presentations of chest pain with good diagnostic accuracy and could prove a significant advance in the management of aortic disease.

genomics↗

bioRxiv2022

Development of methylation-based biomarkers for breast cancer detection by model training and validation in synthetic cell-free DNA

Circulating tumour-derived DNA (ctDNA) carries the genetic and epigenetic characteristics of the tumour from which it is derived and can give information about the biology and tissue origins of the underlying tumour. DNA methylation is an epigenetic mark that is specific to individual tissues and, as methylation profiles are disrupted in tumours, they can indicate the tissue of origin and cancer type of ctDNA. We have developed a set of methylation biomarkers for detecting breast cancer in plasma cell-free DNA (cfDNA). First, we mined publicly available methylation datasets to create synthetic methylation profiles that were modelled to reflect cfDNA from healthy subjects and cancer patients. These profiles were restricted to the most differentially methylated CpGs between breast tumour samples and haematopoietic cells. Regularised logistic regression models were trained using 10-fold cross-validation on synthetic cfDNA datasets with distinct fractions of breast tumour DNA spiked in silico into healthy cfDNA with the addition of 10% of a mix of different tissues. Initial validation with synthetic cfDNA permitted detection of breast cancer-derived DNA with as little as 0.25% tumour DNA spiked in silico into healthy subject cfDNA with an area under ROC curve (AUC) of 0.63. Performances of classifiers increased with increased fractions of spike-in tumour DNA (AUCs 0.77 and 0.93 at tumour DNA fractions 0.5% and 1% respectively). We then combined the most discriminative CpG markers from our models with methylation markers of breast cancer that had already been published to obtain a single marker set. In vitro testing of MCF-7 breast cancer cell line DNA spiked into leukocyte DNA showed highly significant correlation for individual markers between laboratory-measured and published methylation data for MCF-7 and leukocytes (R > 0.89, P < 2.2 x 10-16). These preliminary data indicate promising results for detection of breast cancer cell line DNA using this methylation marker set, which now require testing in cfDNA from breast cancer patients and healthy controls.

cancer biology↗

bioRxiv2021

The Application of The Skin Virome for Human Identification

The use of skin virome for human identification purposes offers a unique approach to instances where a viable and statistically relevant human DNA profile is unavailable. The human skin virome may act as an alternative DNA profile and/or an additional form of probative genetic material. To date, no study has attempted to investigate the human virome over a time series across various physical locations of the body to identify its potential as a tool for human identification. For this study, we set out to evaluate the stability, diversity, and individualization of the human skin virome. An additional goal was to identify viral signatures that can be used in conjunction with traditional forensic STR loci. In order to accomplish this, human virome metagenomes were collected and sequenced from 42 individuals at three anatomical locations (left hand, right hand, and scalp) across multiple collections periods over a 6-month window of time. Assembly dependent and independent bioinformatic approaches were employed, along with a database-based assessment, which resulted in three sets of stable putative viral markers. In total, with the three sets combined, 59 viral species and uncharacterized viral genome assemblies were identified as being significantly stable (P=5.3x10-15). Viral diversity, based on presence or absence, is significantly different across subjects (P<0.001). Here we demonstrate that not only is the human virome applicable to be used for human identification, but we have identified many viral signatures that can be used for forensic applications, thus providing a foundation to the novel field of forensic virology. HighlightsO_LIHere we provide the largest human skin virome study, to date. Our study revealed novel diversity findings of high abundance for certain viral taxa, for example, the Cress-like DNA phages, that have not previously been characterized in human skin viral ecology studies. C_LIO_LIThere were 59 putative human skin viral biomarkers suitable for human identification from the core stable human skin virome of 42 subjects. C_LIO_LIThe putative markers we identified were significantly stable over a 6-month period of time within individuals and across three autosomal locations of left hand, right hand, and scalp. C_LIO_LIDiversity of profiles, based on the presence and absence of our putative marker data set, were significantly different across test subjects. C_LI

microbiology↗

bioRxiv2018

A role for RNA and DNA:RNA hybrids in the modulation of DNA repair by homologous recombination

DNA double-strand breaks (DSBs) are toxic DNA lesions which, if not properly repaired, may lead to genomic instability, cell death and senescence. Damage-induced long non-coding RNAs (dilncRNAs) are transcribed from broken DNA ends and contribute to DNA damage response (DDR) signaling. Here we show that dilncRNAs play a role in DSB repair by homologous recombination (HR) by contributing to the recruitment of the HR proteins BRCA1, BRCA2, and RAD51, without affecting DNA-end resection. In S/G2-phase cells, dilncRNAs pair to the resected DNA ends and form DNA:RNA hybrids, which are recognized by BRCA1 and promote its recruitment to DSBs. We also show that RNase H2 is in a complex with the HR proteins BRCA1, PALB2, BRCA2, and RAD51, and that it localizes to DSBs in the S/G2 cell-cycle phase. BRCA2 controls DNA:RNA hybrid levels at DSBs by mediating RNase H2 recruitment and, therefore, hybrids degradation. These results demonstrate that regulated DNA:RNA hybrid levels at DSBs contribute to HR-mediated repair.

cell biology↗