Abstracts From the First Annual Research Day Hosted by the Michigan State University College of Osteopathic Medicine, Novi, Michigan, May 15, 2023.

The Spartan Medical Research Journal (SMRJ) is pleased to publish abstracts from the First Annual Research Day hosted by the Michigan State University College of Osteopathic Medicine (MSUCOM), held in Novi, Michigan, on May 15, 2023. Sponsored by MSUCOM, the Statewide Campus System (SCS), and Research, Innovation, and Scholarly Engagement (RISE), this event showcased a total of 139 selected research abstracts following a meticulous blinded review by the MSUCOM Research Day Planning Committee and SMRJ editorial staff. These abstracts were subsequently presented at the MSUCOM First Annual Research Day in 2023, with awards for exceptional oral and poster presentations conferred on May 15, 2023. Of the 139 presentations that were ultimately chosen, 45 authors consented and elected to have their abstracts published in SMRJ. The abstracts from 2023 encompass a wide array of contemporary medical and clinical subjects, incorporating a variety of research designs that cover basic science, clinical research, case reports, medical education, and quality improvement. While abstracts offer concise overview of research projects or presentations, they do not permit a comprehensive evaluation of the scientific rigor employed in the respective works. Although these abstracts offer preliminary results that may necessitate further refinement and validation, they serve a vital function in disseminating novel research concepts and advancements in the discipline of medicine. This knowledge-sharing promotes meaningful dialogue among researchers, clinicians, and educators, thereby making a valuable contribution to the collective body of knowledge in the fields of medical sciences and osteopathic medicine. Andrea Amalfitano, DO, PhD Osteopathic Heritage Foundation Professor of Pediatrics, Microbiology and Molecular Genetics Professor, BioMolecular Science Gateway Editor-in-Chief, Spartan Medical Research Journal (SMRJ) MSU College of Osteopathic Medicine- Statewide Campus System C. Patricia Obando S., PhD Associate Dean and DIO, Graduate Medical Education Associate Professor- MSU College of Osteopathic Medicine- Statewide Campus System Rana Ismail, PhD, MSc, CPHQ Director of Research Editor, Spartan Medical Research Journal (SMRJ) MSU College of Osteopathic Medicine- Statewide Campus System Francis Akenami, BMLS, PhD, MSc, FIMLS Managing Editor Spartan Medical Research Journal (SMRJ) MSU College of Osteopathic Medicine- Statewide Campus System.

Recurrent Duplication and Diversification of a Vital DNA Repair Gene Family Across Drosophila.

Maintaining genome integrity is vital for organismal survival and reproduction. Essential, broadly conserved DNA repair pathways actively preserve genome integrity. However, many DNA repair proteins evolve adaptively. Ecological forces like UV exposure are classically cited drivers of DNA repair evolution. Intrinsic forces like repetitive DNA, which also imperil genome integrity, have received less attention. We recently reported that a Drosophila melanogaster-specific DNA satellite array triggered species-specific, adaptive evolution of a DNA repair protein called Spartan/MH. The Spartan family of proteases cleave hazardous, covalent crosslinks that form between DNA and proteins ("DNA-protein crosslink repair"). Appreciating that DNA satellites are both ubiquitous and universally fast-evolving, we hypothesized that satellite DNA turnover spurs adaptive evolution of DNA-protein crosslink repair beyond a single gene and beyond the D. melanogaster lineage. This hypothesis predicts pervasive Spartan gene family diversification across Drosophila species. To study the evolutionary history of the Drosophila Spartan gene family, we conducted population genetic, molecular evolution, phylogenomic, and tissue-specific expression analyses. We uncovered widespread signals of positive selection across multiple Spartan family genes and across multiple evolutionary timescales. We also detected recurrent Spartan family gene duplication, divergence, and gene loss. Finally, we found that ovary-enriched parent genes consistently birthed functionally diverged, testis-enriched daughter genes. To account for Spartan family diversification, we introduce a novel mechanistic model of antagonistic coevolution that links DNA satellite evolution and adaptive regulation of Spartan protease activity. This framework promises to accelerate our understanding of how DNA repeats drive recurrent evolutionary innovation to preserve genome integrity.

Design of efficient binary multiplier architecture using hybrid compressor with FPGA implementation.

In signal processing applications, the multipliers are essential component of arithmetic functional units in many applications, like digital signal processors, image/video processing, Machine Learning, Cryptography and Arithmetic & Logical units (ALU). In recent years, Profuse multipliers are there. In that, Vedic multiplier is one of the high-performance multiplications and it is used to signal/image processing applications. In order to ameliorate the performance of this multiplier further, by proposed a novel multiplier using hybrid compressor. The proposed hybrid compressor-based multiplier is designed and implemented in Field programmable Gate Array (FPGA-spartan 6). The synthesis result shows that the speed of proposed hybrid compressor-based multiplier gets improved as compared to Array multiplier (35.83%), Wallace tree multiplier (34.58%), Vedic Multiplier based on Carry look ahead adder (CLA) (28.49%), Vedic Multiplier based on Ripple carry adder (RCA) (20.65%), Booth Multiplication (21.65%) and Vedic Multiplication based on Han-Carlson Adder (HCA) (20.10%) and Hybrid multiplier using Carry Select Adder (CSELA) (17.81%) and Hybrid Vedic Multiplier (7.15%).

Prostate-specific Membrane Antigen Positron Emission Tomography-detected Disease Extent and Overall Survival of Patients with High-risk Nonmetastatic Castration-resistant Prostate Cancer: An International Multicenter Retrospective Study.

Previously, we demonstrated that prostate-specific membrane antigen positron emission tomography (PSMA-PET) revealed distant metastases in 109/200 patients (39% distant nodes, 24% bone, and 6% visceral organ) with nonmetastatic castration-resistant prostate cancer (nmCRPC) and high-risk features (International Society of Urological Pathology score ≥4 and/or prostate-specific antigen doubling time ≤10 mo) without metastases by conventional imaging. However, the impact of disease extent determined by PSMA-PET on patient outcomes is unknown. We followed these 200 patients for a median of 43 mo after PSMA-PET and retrospectively assessed the association between patient characteristics, PSMA-PET findings, treatment management, and outcomes using a Kaplan-Meier model and Cox multivariable regressions. Among assessed disease characteristics, polymetastatic disease (five or more distant lesions on PET) was independently associated with shorter overall survival (OS; median 61 mo vs not reached; hazard ratio [95% confidence interval], 1.81 [1.00-3.27]; p = 0.050) and time to new metastases (median 38 vs 60 mo; 1.80 [1.10-2.96]; p = 0.019), and initial pN1 status with shorter OS (55 mo vs not reached; 1.94 [1.12-3.37]; p = 0.019). Following PSMA-PET, locoregional salvage therapies were used most commonly in no/local disease (58%), and androgen receptor signaling inhibitors were used in distant metastatic disease (51%). PSMA-PET provides additional risk stratification for patients with nmCRPC. Polymetastatic disease (five or more distant lesions) is associated with worse outcomes. PATIENT SUMMARY: A novel sensitive imaging technology, called prostate-specific membrane antigen positron emission tomography (PSMA-PET), allows doctors to detect the spread of prostate cancer, known as distant metastases, earlier and more accurately than in the past. In our study, PSMA-PET detected none to many metastases in patients who were considered free of distant metastasis by conventional imaging. These findings predicted outcomes and were used to select appropriate treatment.

Linking Expression of Cell-Surface Receptors with Transcription Factors by Computational Analysis of Paired Single-Cell Proteomes and Transcriptomes.

Complex signaling and transcriptional programs control the development and physiology of specialized cell types. Genetic perturbations in these programs cause human cancers to arise from a diverse set of specialized cell types and developmental states. Understanding these complex systems and their potential to drive cancer is critical for the development of immunotherapies and druggable targets. Pioneering single-cell multi-omics technologies that analyze transcriptional states have been coupled with the expression of cell-surface receptors. This chapter describes SPaRTAN (Single-cell Proteomic and RNA-based Transcription factor Activity Network), a computational framework, to link transcription factors with cell-surface protein expression. SPaRTAN uses CITE-seq (cellular indexing of transcriptomes and epitopes by sequencing) data and cis-regulatory sites to model the effect of interactions between transcription factors and cell-surface receptors on gene expression. We demonstrate the pipeline for SPaRTAN using CITE-seq data from peripheral blood mononuclear cells.

Cross-species incompatibility between a DNA satellite and the Drosophila Spartan homolog poisons germline genome integrity.

Satellite DNA spans megabases of eukaryotic sequence and evolves rapidly.1-6 Paradoxically, satellite-rich genomic regions mediate strictly conserved, essential processes such as chromosome segregation and nuclear structure.7-10 A leading resolution to this paradox posits that satellite DNA and satellite-associated chromosomal proteins coevolve to preserve these essential functions.11 We experimentally test this model of intragenomic coevolution by conducting the first evolution-guided manipulation of both chromosomal protein and DNA satellite. The 359bp satellite spans an 11 Mb array in Drosophila melanogaster that is absent from its sister species, Drosophila simulans.12-14 This species-specific DNA satellite colocalizes with the adaptively evolving, ovary-enriched protein, maternal haploid (MH), the Drosophila homolog of Spartan.15 To determine if MH and 359bp coevolve, we swapped the D. simulans version of MH ("MH[sim]") into D. melanogaster. MH[sim] triggers ovarian cell death, reduced ovary size, and loss of mature eggs. Surprisingly, the D. melanogaster mh-null mutant has no such ovary phenotypes,15 suggesting that MH[sim] is toxic in a D. melanogaster background. Using both cell biology and genetics, we discovered that MH[sim] poisons oogenesis through a DNA-damage pathway. Remarkably, deleting the D. melanogaster-specific 359bp satellite array completely restores mh[sim] germline genome integrity and fertility, consistent with a history of coevolution between these two fast-evolving loci. Germline genome integrity and fertility are also restored by overexpressing topoisomerase II (Top2), suggesting that MH[sim] interferes with Top2-mediated processing of 359bp. The observed 359bp-MH[sim] cross-species incompatibility supports a model under which seemingly inert repetitive DNA and essential chromosomal proteins must coevolve to preserve germline genome integrity.

DNA Structure-Specific Cleavage of DNA-Protein Crosslinks by the SPRTN Protease.

Repair of covalent DNA-protein crosslinks (DPCs) by DNA-dependent proteases has emerged as an essential genome maintenance mechanism required for cellular viability and tumor suppression. However, how proteolysis is restricted to the crosslinked protein while leaving surrounding chromatin proteins unharmed has remained unknown. Using defined DPC model substrates, we show that the DPC protease SPRTN displays strict DNA structure-specific activity. Strikingly, SPRTN cleaves DPCs at or in direct proximity to disruptions within double-stranded DNA. In contrast, proteins crosslinked to intact double- or single-stranded DNA are not cleaved by SPRTN. NMR spectroscopy data suggest that specificity is not merely affinity-driven but achieved through a flexible bipartite strategy based on two DNA binding interfaces recognizing distinct structural features. This couples DNA context to activation of the enzyme, tightly confining SPRTN's action to biologically relevant scenarios.

DNA-Histone Cross-Links: Formation and Repair.

The nucleosome is a stretch of DNA wrapped around a histone octamer. Electrostatic interactions and hydrogen bonds between histones and DNA are vital for the stable organization of nucleosome core particles, and for the folding of chromatin into more compact structures, which regulate gene expression via controlled access to DNA. As a drawback of tight association, under genotoxic stress, DNA can accidentally cross-link to histone in a covalent manner, generating a highly toxic DNA-histone cross-link (DHC). DHC is a bulky lesion that can impede DNA transcription, replication, and repair, often with lethal consequences. The chemotherapeutic agent cisplatin, as well as ionizing and ultraviolet irradiations and endogenously occurring reactive aldehydes, generate DHCs by forming either stable or transient covalent bonds between DNA and side-chain amino groups of histone lysine residues. The mechanisms of DHC repair start to unravel, and certain common principles of DNA-protein cross-link (DPC) repair mechanisms that participate in the removal of cross-linked histones from DNA have been described. In general, DPC is removed via a two-step repair mechanism. First, cross-linked proteins are degraded by specific DPC proteases or by the proteasome, relieving steric hindrance. Second, the remaining DNA-peptide cross-links are eliminated in various DNA repair pathways. Delineating the molecular mechanisms of DHC repair would help target specific DNA repair proteins for therapeutic intervention to combat tumor resistance to chemotherapy and radiotherapy.

GCNA Interacts with Spartan and Topoisomerase II to Regulate Genome Stability.

GCNA proteins are expressed across eukarya in pluripotent cells and have conserved functions in fertility. GCNA homologs Spartan (DVC-1) and Wss1 resolve DNA-protein crosslinks (DPCs), including Topoisomerase-DNA adducts, during DNA replication. Here, we show that GCNA mutants in mouse and C. elegans display defects in genome maintenance including DNA damage, aberrant chromosome condensation, and crossover defects in mouse spermatocytes and spontaneous genomic rearrangements in C. elegans. We show that GCNA and topoisomerase II (TOP2) physically interact in both mice and worms and colocalize on condensed chromosomes during mitosis in C. elegans embryos. Moreover, C. elegans gcna-1 mutants are hypersensitive to TOP2 poison. Together, our findings support a model in which GCNA provides genome maintenance functions in the germline and may do so, in part, by promoting the resolution of TOP2 DPCs.

Geostatistical analysis of precipitation in the island of Crete (Greece) based on a sparse monitoring network.

Based on the predictions of General Circulation Models, significant reduction of precipitation in Mediterranean areas is a possible scenario. Hence, better understanding of the spatial and temporal precipitation patterns is necessary in order to quantify desertification risks and design suitable mitigation measures. This study uses monthly precipitation measurements from a sparse network of 54 monitoring stations on the Mediterranean island of Crete (Greece). The study period extends from 1948 to 2012. The data reveal strong correlations between the western and eastern parts of the island. However, the average annual precipitation in the West is about 450 mm higher than that in the East. We construct a spatial model of average annual precipitation in Crete. The model involves a topographic trend and residuals with anisotropic spatial correlations which are fitted with a recently developed variogram function. We use regression kriging to generate annual precipitation maps and to identify locations of high estimation uncertainty. To our knowledge, this is the most detailed spatial analysis of precipitation in Crete to date. We present the analysis in detail for the year 1971. The trend accounts for ≈ 74% of the total variance. The highest precipitation estimate is 2331 mm in the West and 1781 mm in the East. The highest relative estimation uncertainty (≈ 20%) is observed along the southeastern coastline of the island, where the lowest values of annual precipitation are observed. This region includes one of the major agricultural areas of the island. The same overall patterns are found for other years in the study. Finally, we find no statistical evidence for a decrease in the global (over the entire island) annual precipitation during the study period.

Kasuistik: Hochrisiko-M0CRPC-Therapie mit Apalutamid.

Stieg bei einem Prostatakarzinom-Patienten, der keine Metastasen in der konventionellen Bildgebung hatte, unter der Androgendeprivation (ADT) der PSA-Wert, wurde bislang meist die ADT bis zum Auftreten von Metastasen fortgeführt. Der vorliegende Fall eines Patienten aus der SPARTAN-Studie ist ein Beispiel für die positiven Effekte, die Apalutamid in der Situation erzielen kann.

Structural Insight into DNA-Dependent Activation of Human Metalloprotease Spartan.

The DNA-dependent metalloprotease Spartan (SPRTN) cleaves DNA-protein crosslinks (DPCs) and protects cells from DPC-induced genome instability. Germline mutations of SPRTN are linked to human Ruijs-Aalfs syndrome (RJALS) characterized by progeria and early-onset hepatocellular carcinoma. The mechanism of DNA-mediated activation of SPRTN is not understood. Here, we report the crystal structure of the human SPRTN SprT domain bound to single-stranded DNA (ssDNA). Our structure reveals a Zn2+-binding sub-domain (ZBD) in SprT that shields its active site located in the metalloprotease sub-domain (MPD). The narrow catalytic groove between MPD and ZBD only permits cleavage of flexible substrates. The ZBD contains an ssDNA-binding site, with a DNA-base-binding pocket formed by aromatic residues. Mutations of ssDNA-binding residues diminish the protease activity of SPRTN. We propose that the ZBD contributes to the ssDNA specificity of SPRTN, restricts the access of globular substrates, and positions DPCs, which may need to be partially unfolded, for optimal cleavage.

Management of Nonmetastatic Castration-Resistant Prostate Cancer: Recent Advances and Future Direction.

OPINION STATEMENT: Nonmetastatic castration-resistant prostate cancer (nmCRPC) comprises a relatively narrow niche of advanced prostate cancer, but the treatment landscape for men with nmCRPC has drastically changed over the past year. Prior to the SPARTAN and PROSPER trials, men with nmCRPC were commonly treated with first-generation androgen receptor antagonists, such as bicalutamide or flutamide, or with estrogens or ketoconazole, none of which were associated with any proven survival benefit. The SPARTAN trial evaluated apalutamide versus placebo for men with nmCRPC and found that apalutamide significantly improved metastasis-free survival (MFS), the primary endpoint of this trial. Similarly, the PROSPER trial showed that enzalutamide significantly improved MFS compared with placebo for men with nmCRPC. In both trials, the data for overall survival was immature at the time of analysis. The SPARTAN and PROSPER trials led to the approval of apalutamide and enzalutamide, respectively, for men with nmCRPC. More recently, the phase 3 trial ARAMIS showed that darolutamide, a novel androgen receptor antagonist, also improves MFS compared with placebo for men with nmCRPC, and this trial is expected to garner regulatory approval for darolutamide in the nmCRPC setting. Novel imaging modalities are becoming more prevalent for the diagnostic evaluation of men with prostate cancer and are more sensitive than conventional bone or CT scans for detection of oligometastatic disease that previously was undetected. These modalities are likely to reduce the incidence and prevalence of nmCRPC in the near future. Ultimately, the treatment options for men with nmCRPC have significantly improved over the past 2 years.

SPARTAN promotes genetic diversification of the immunoglobulin-variable gene locus in avian DT40 cells.

Prolonged replication arrest on damaged templates is a cause of fork collapse, potentially resulting in genome instability. Arrested replication is rescued by translesion DNA synthesis (TLS) and homologous recombination (HR)-mediated template switching. SPARTAN, a ubiquitin-PCNA-interacting regulator, regulates TLS via mechanisms incompletely understood. Here we show that SPARTAN promotes diversification of the chicken DT40 immunoglobulin-variable λ gene by facilitating TLS-mediated hypermutation and template switch-mediated gene-conversion, both induced by replication blocks at abasic sites. SPARTAN-/- and SPARTAN-/-/Polη-/-/Polζ-/- cells showed defective and similar decrease in hypermutation rates, as well as alterations in the mutation spectra, with decreased dG-to-dC transversions and increased dG-to-dA transitions. Strikingly, SPARTAN-/- cells also showed reduced template switch-mediated gene-conversion at the immunoglobulin locus, while being proficient in HR-mediated double strand break repair, and sister chromatid recombination. Notably, SPARTAN's ubiquitin-binding zinc-finger 4 domain, but not the PCNA interacting peptide domain or its DNA-binding domain, was specifically required for the promotion of immunoglobulin gene-conversion, while all these three domains were shown to contribute similarly to TLS. In all, our results suggest that SPARTAN mediates TLS in concert with the Polη-Polζ pathway and that it facilitates HR-mediated template switching at a subset of stalled replication forks, potentially by interacting with unknown ubiquitinated proteins.

DNA-Protein Crosslink Proteolysis Repair.

Proteins that are covalently bound to DNA constitute a specific type of DNA lesion known as DNA-protein crosslinks (DPCs). DPCs represent physical obstacles to the progression of DNA replication. If not repaired, DPCs cause stalling of DNA replication forks that consequently leads to DNA double-strand breaks, the most cytotoxic DNA lesion. Although DPCs are common DNA lesions, the mechanism of DPC repair was unclear until now. Recent work unveiled that DPC repair is orchestrated by proteolysis performed by two distinct metalloproteases, SPARTAN in metazoans and Wss1 in yeast. This review summarizes recent discoveries on two proteases in DNA replication-coupled DPC repair and establishes DPC proteolysis repair as a separate DNA repair pathway for genome stability and protection from accelerated aging and cancer.

Quantitative microscopy uncovers ploidy changes during mitosis in live Drosophila embryos and their effect on nuclear size.

Time-lapse microscopy is a powerful tool to investigate cellular and developmental dynamics. In Drosophila melanogaster, it can be used to study division cycles in embryogenesis. To obtain quantitative information from 3D time-lapse data and track proliferating nuclei from the syncytial stage until gastrulation, we developed an image analysis pipeline consisting of nuclear segmentation, tracking, annotation and quantification. Image analysis of maternal-haploid (mh) embryos revealed that a fraction of haploid syncytial nuclei fused to give rise to nuclei of higher ploidy (2n, 3n, 4n). Moreover, nuclear densities in mh embryos at the mid-blastula transition varied over threefold. By tracking synchronized nuclei of different karyotypes side-by-side, we show that DNA content determines nuclear growth rate and size in early interphase, while the nuclear to cytoplasmic ratio constrains nuclear growth during late interphase. mh encodes the Drosophila ortholog of human Spartan, a protein involved in DNA damage tolerance. To explore the link between mh and chromosome instability, we fluorescently tagged Mh protein to study its subcellular localization. We show Mh-mKO2 localizes to nuclear speckles that increase in numbers as nuclei expand in interphase. In summary, quantitative microscopy can provide new insights into well-studied genes and biological processes.

The DNA-binding box of human SPARTAN contributes to the targeting of Polη to DNA damage sites.

Inappropriate repair of UV-induced DNA damage results in human diseases such as Xeroderma pigmentosum (XP), which is associated with an extremely high risk of skin cancer. A variant form of XP is caused by the absence of Polη, which is normally able to bypass UV-induced DNA lesions in an error-free manner. However, Polη is highly error prone when replicating undamaged DNA and, thus, the regulation of the proper targeting of Polη is crucial for the prevention of mutagenesis and UV-induced cancer formation. Spartan is a novel regulator of the damage tolerance pathway, and its association with Ub-PCNA has a role in Polη targeting; however, our knowledge about its function is only rudimentary. Here, we describe a new biochemical property of purified human SPARTAN by showing that it is a DNA-binding protein. Using a DNA binding mutant, we provide in vivo evidence that DNA binding by SPARTAN regulates the targeting of Polη to damage sites after UV exposure, and this function contributes highly to its DNA-damage tolerance function.

Comparison of four different nerve conduction techniques of the superficial fibular sensory nerve.

INTRODUCTION: There are many different nerve conduction study (NCS) techniques to study the superficial fibular sensory nerve (SFSN). We present reference distal latency values and comparative data regarding 4 different NCS for the SFSN. METHODS: Four different NCS techniques, Spartan technique, Izzo techniques (medial and intermediate dorsal cutaneous branches), and Daube technique, were performed on (114) healthy volunteers. A total of 108 subjects with 164 legs were included. RESULTS: The mean latency of the Spartan technique was longest (3.9 ± 0.3 ms) while the Daube technique was the shortest (3.6 ± 0.7 ms). The mean amplitude of the Daube technique displayed the highest (15.2 ± 8.2 µV) with the Spartan technique having the lowest (8.7 ± 4.2 µV). Among the absent sensory nerve action potentials (SNAPs), the Spartan technique was absent only twice (1.2%) and the Izzo Medial technique was absent more than the other techniques (2.9%). CONCLUSIONS: All 4 techniques were reliable methods for obtaining the superficial fibular nerve SNAP, present in 95% of individuals. Muscle Nerve 56: 458-462, 2017.

SPRTN is a mammalian DNA-binding metalloprotease that resolves DNA-protein crosslinks.

Ruijs-Aalfs syndrome is a segmental progeroid syndrome resulting from mutations in the SPRTN gene. Cells derived from patients with SPRTN mutations elicit genomic instability and people afflicted with this syndrome developed hepatocellular carcinoma. Here we describe the molecular mechanism by which SPRTN contributes to genome stability and normal cellular homeostasis. We show that SPRTN is a DNA-dependent mammalian protease required for resolving cytotoxic DNA-protein crosslinks (DPCs)- a function that had only been attributed to the metalloprotease Wss1 in budding yeast. We provide genetic evidence that SPRTN and Wss1 function distinctly in vivo to resolve DPCs. Upon DNA and ubiquitin binding, SPRTN can elicit proteolytic activity; cleaving DPC substrates and itself. SPRTN null cells or cells derived from patients with Ruijs-Aalfs syndrome are impaired in the resolution of covalent DPCs in vivo. Collectively, SPRTN is a mammalian protease required for resolving DNA-protein crosslinks in vivo whose function is compromised in Ruijs-Aalfs syndrome patients.

Mechanism and Regulation of DNA-Protein Crosslink Repair by the DNA-Dependent Metalloprotease SPRTN.

Covalent DNA-protein crosslinks (DPCs) are toxic DNA lesions that interfere with essential chromatin transactions, such as replication and transcription. Little was known about DPC-specific repair mechanisms until the recent identification of a DPC-processing protease in yeast. The existence of a DPC protease in higher eukaryotes is inferred from data in Xenopus laevis egg extracts, but its identity remains elusive. Here we identify the metalloprotease SPRTN as the DPC protease acting in metazoans. Loss of SPRTN results in failure to repair DPCs and hypersensitivity to DPC-inducing agents. SPRTN accomplishes DPC processing through a unique DNA-induced protease activity, which is controlled by several sophisticated regulatory mechanisms. Cellular, biochemical, and structural studies define a DNA switch triggering its protease activity, a ubiquitin switch controlling SPRTN chromatin accessibility, and regulatory autocatalytic cleavage. Our data also provide a molecular explanation on how SPRTN deficiency causes the premature aging and cancer predisposition disorder Ruijs-Aalfs syndrome.