The CUE1 domain of the SNF2-like chromatin remodeler SMARCAD1 mediates its association with KRAB-associated protein 1 (KAP1) and KAP1 target genes

The role of Smarcad1 in retroviral repression in mouse embryonic stem cells

BACKGROUND

Moloney murine leukemia virus (MLV) replication is suppressed in mouse embryonic stem cells (ESCs) by the Trim28-SETDB1 complex. The chromatin remodeler Smarcad1 interacts with Trim28 and was suggested to allow the deposition of the histone variant H3.3. However, the role of Trim28, H3.3, and Smarcad1 in MLV repression in ESCs still needs to be fully understood.

RESULTS

In this study, we used MLV to explore the role of Smarcad1 in retroviral silencing in ESCs. We show that Smarcad1 is immediately recruited to the MLV provirus. Based on the repression dynamics of a GFP-reporter MLV, our findings suggest that Smarcad1 plays a critical role in the establishment and maintenance of MLV repression, as well as other Trim28-targeted genomic loci. Furthermore, Smarcad1 is important for stabilizing and strengthening Trim28 binding to the provirus over time, and its presence around the provirus is needed for proper deposition of H3.3 on the provirus. Surprisingly, the combined depletion of Smarcad1 and Trim28 results in enhanced MLV derepression, suggesting that these two proteins may also function independently to maintain repressive chromatin states.

CONCLUSIONS

Overall, the results of this study provide evidence for the crucial role of Smarcad1 in the silencing of retroviral elements in embryonic stem cells. Further research is needed to fully understand how Smarcad1 and Trim28 cooperate and their implications for gene expression and genomic stability.

The Conserved Chromatin Remodeler SMARCAD1 Interacts with TFIIIC and Architectural Proteins in Human and Mouse

In vertebrates, SMARCAD1 participates in transcriptional regulation, heterochromatin maintenance, DNA repair, and replication. The molecular basis underlying its involvement in these processes is not well understood. We identified the RNA polymerase III general transcription factor TFIIIC as an interaction partner of native SMARCAD1 in mouse and human models using endogenous co-immunoprecipitations. TFIIIC has dual functionality, acting as a general transcription factor and as a genome organizer separating chromatin domains. We found that its partnership with SMARCAD1 is conserved across different mammalian cell types, from somatic to pluripotent cells. Using purified proteins, we confirmed that their interaction is direct. A gene expression analysis suggested that SMARCAD1 is dispensable for TFIIIC function as an RNA polymerase III transcription factor in mouse ESCs. The distribution of TFIIIC and SMARCAD1 in the ESC genome is distinct, and unlike in yeast, SMARCAD1 is not enriched at active tRNA genes. Further analysis of SMARCAD1-binding partners in pluripotent and differentiated mammalian cells reveals that SMARCAD1 associates with several factors that have key regulatory roles in chromatin organization, such as cohesin, laminB, and DDX5. Together, our work suggests for the first time that the SMARCAD1 enzyme participates in genome organization in mammalian nuclei through interactions with architectural proteins.

A SAM-key domain required for enzymatic activity of the Fun30 nucleosome remodeler

Fun30 is the prototype of the Fun30-SMARCAD1-ETL subfamily of nucleosome remodelers involved in DNA repair and gene silencing. These proteins appear to act as single-subunit nucleosome remodelers, but their molecular mechanisms are, at this point, poorly understood. Using multiple sequence alignment and structure prediction, we identify an evolutionarily conserved domain that is modeled to contain a SAM-like fold with one long, protruding helix, which we term SAM-key. Deletion of the SAM-key within budding yeast Fun30 leads to a defect in DNA repair and gene silencing similar to that of the fun30Δ mutant. In vitro, Fun30 protein lacking the SAM-key is able to bind nucleosomes but is deficient in DNA-stimulated ATPase activity and nucleosome sliding and eviction. A structural model based on AlphaFold2 prediction and verified by crosslinking-MS indicates an interaction of the long SAM-key helix with protrusion I, a subdomain located between the two ATPase lobes that is critical for control of enzymatic activity. Mutation of the interaction interface phenocopies the domain deletion with a lack of DNA-stimulated ATPase activation and a nucleosome-remodeling defect, thereby confirming a role of the SAM-key helix in regulating ATPase activity. Our data thereby demonstrate a central role of the SAM-key domain in mediating the activation of Fun30 catalytic activity, thus highlighting the importance of allosteric activation for this class of enzymes.

Trim28 citrullination maintains mouse embryonic stem cell pluripotency via regulating Nanog and Klf4 transcription

Protein citrullination, including histone H1 and H3 citrullination, is important for transcriptional regulation, DNA damage response, and pluripotency of embryonic stem cells (ESCs). Tripartite motif containing 28 (Trim28), an embryonic development regulator involved in ESC self-renewal, has recently been identified as a novel substrate for citrullination by Padi4. However, the physiological functions of Trim28 citrullination and its role in regulating the chromatin structure and gene transcription of ESCs remain unknown. In this paper, we show that Trim28 is specifically citrullinated in mouse ESCs (mESCs), and that the loss of Trim28 citrullination induces loss of pluripotency. Mechanistically, Trim28 citrullination enhances the interaction of Trim28 with Smarcad1 and prevents chromatin condensation. Additionally, Trim28 citrullination regulates mESC pluripotency by promoting transcription of Nanog and Klf4 which it does by increasing the enrichment of H3K27ac and H3K4me3 and decreasing the enrichment of H3K9me3 in the transcriptional regulatory region. Thus, our findings suggest that Trim28 citrullination is the key for the epigenetic activation of pluripotency genes and pluripotency maintenance of ESCs. Together, these results uncover a role Trim28 citrullination plays in pluripotency regulation and provide novel insight into how citrullination of proteins other than histones regulates chromatin compaction.

Structure and functional mapping of the KRAB-KAP1 repressor complex

Transposable elements are a genetic reservoir from which new genes and regulatory elements can emerge. However, expression of transposable elements can be pathogenic and is therefore tightly controlled. KRAB domain-containing zinc finger proteins (KRAB-ZFPs) recruit the co-repressor KRAB-associated protein 1 (KAP1/TRIM28) to regulate many transposable elements, but how KRAB-ZFPs and KAP1 interact remains unclear. Here, we report the crystal structure of the KAP1 tripartite motif (TRIM) in complex with the KRAB domain from a human KRAB-ZFP, ZNF93. Structure-guided mutations in the KAP1-KRAB binding interface abolished repressive activity in an epigenetic transcriptional silencing assay. Deposition of H3K9me3 over thousands of loci is lost genome-wide in cells expressing a KAP1 variant with mutations that abolish KRAB binding. Our work identifies and functionally validates the KRAB-KAP1 molecular interface, which is critical for a central transcriptional control axis in vertebrates. In addition, the structure-based prediction of KAP1 recruitment efficiency will enable optimization of KRABs used in CRISPRi.

Fun30 and Rtt109 Mediate Epigenetic Regulation of the DNA Damage Response Pathway in C. albicans

Fun30, an ATP-dependent chromatin remodeler from S. cerevisiae, is known to mediate both regulation of gene expression as well as DNA damage response/repair. The Fun30 from C. albicans has not yet been elucidated. We show that C. albicans Fun30 is functionally homologous to both S. cerevisiae Fun30 and human SMARCAD1. Further, C. albicans Fun30 can mediate double-strand break end resection as well as regulate gene expression. This protein regulates transcription of RTT109, TEL1, MEC1, and SNF2-genes that encode for proteins involved in DNA damage response and repair pathways. The regulation mediated by C. albicans Fun30 is dependent on its ATPase activity. The expression of FUN30, in turn, is regulated by histone H3K56 acetylation catalyzed by Rtt109 and encoded by RTT109. The RTT109Hz/FUN30Hz mutant strain shows sensitivity to oxidative stress and resistance to MMS as compared to the wild-type strain. Quantitative PCR showed that the sensitivity to oxidative stress results from downregulation of MEC1, RAD9, MRC1, and RAD5 expression; ChIP experiments showed that Fun30 but not H3K56ac regulates the expression of these genes in response to oxidative stress. In contrast, upon treatment with MMS, the expression of RAD9 is upregulated, which is modulated by both Fun30 and H3K56 acetylation. Thus, Fun30 and H3K56 acetylation mediate the response to genotoxic agents in C. albicans by regulating the expression of DNA damage response and repair pathway genes.

Arabidopsis CHROMATIN REMODELING 19 acts as a transcriptional repressor and contributes to plant pathogen resistance

Chromatin remodelers act in an ATP-dependent manner to modulate chromatin structure and thus genome function. Here, we report that the Arabidopsis (Arabidopsis thaliana) remodeler CHROMATIN REMODELING19 (CHR19) is enriched in gene body regions, and its depletion causes massive changes in nucleosome position and occupancy in the genome. Consistent with these changes, an in vitro assay verified that CHR19 can utilize ATP to slide nucleosomes. A variety of inducible genes, including several important genes in the salicylic acid (SA) and jasmonic acid (JA) pathways, were transcriptionally upregulated in the chr19 mutant under normal growth conditions, indicative of a role of CHR19 in transcriptional repression. In addition, the chr19 mutation triggered higher susceptibility to the JA pathway-defended necrotrophic fungal pathogen Botrytis cinerea, but did not affect the growth of the SA pathway-defended hemibiotrophic bacterial pathogen Pseudomonas syringae pv. tomato DC3000. Expression of CHR19 was tissue-specific and inhibited specifically by SA treatment. Such inhibition significantly decreased the local chromatin enrichment of CHR19 at the associated SA pathway genes, which resulted in their full activation upon SA treatment. Overall, our findings clarify CHR19 to be a novel regulator acting at the chromatin level to impact the transcription of genes underlying plant resistance to different pathogens.

Huriez syndrome: Additional pathogenic variants supporting allelism to SMARCAD syndrome

Huriez syndrome (HRZ, OMIM181600) is a rare genodermatosis characterized by scleroatrophic hands and feet, hypoplastic nails, palmoplantar keratoderma, and predisposition to cutaneous squamous cell carcinoma (cSCC). We report herein three HRZ families from Croatia, the Netherlands, and Germany. Deep sequencing followed by Sanger validation, confirmed the presence of germline causative SMARCAD1 heterozygous pathogenic variants. All seven HRZ patients displayed hypohidrosis, adermatoglyphia, and one patient developed cSCC at 32 years of age. Two novel monoallelic germline mutations were identified which are predicted to disrupt the first exon-intron boundary of the skin-specific SMARCAD1 isoform. On the basis of phenotypic and genotypic convergence with Adermatoglyphia (OMIM136000) and Basan syndrome (OMIM129200), our results lend credence to the notion that these three Mendelian disorders are allelic. We propose adding Huriez syndrome to the previously suggested SMARCAD syndrome designation, which was originally invoked to describe the spectrum of monogenic disorders between Adermatoglyphia and Basan syndrome.

RIF1 and KAP1 differentially regulate the choice of inactive versus active X chromosomes

The onset of random X chromosome inactivation in mouse requires the switch from a symmetric to an asymmetric state, where the identities of the future inactive and active X chromosomes are assigned. This process is known as X chromosome choice. Here, we show that RIF1 and KAP1 are two fundamental factors for the definition of this transcriptional asymmetry. We found that at the onset of differentiation of mouse embryonic stem cells (mESCs), biallelic up-regulation of the long non-coding RNA Tsix weakens the symmetric association of RIF1 with the Xist promoter. The Xist allele maintaining the association with RIF1 goes on to up-regulate Xist RNA expression in a RIF1-dependent manner. Conversely, the promoter that loses RIF1 gains binding of KAP1, and KAP1 is required for the increase in Tsix levels preceding the choice. We propose that the mutual exclusion of Tsix and RIF1, and of RIF1 and KAP1, at the Xist promoters establish a self-sustaining loop that transforms an initially stochastic event into a stably inherited asymmetric X-chromosome state.

SMARCAD1 is an ATP-dependent histone octamer exchange factor with de novo nucleosome assembly activity

The adenosine 5′-triphosphate (ATP)–dependent chromatin remodeler SMARCAD1 acts on nucleosomes during DNA replication, repair, and transcription, but despite its implication in disease, information on its function and biochemical activities is scarce. Chromatin remodelers use the energy of ATP hydrolysis to slide nucleosomes, evict histones, or exchange histone variants. Here, we show that SMARCAD1 transfers the entire histone octamer from one DNA segment to another in an ATP-dependent manner but is also capable of de novo nucleosome assembly from histone octamer because of its ability to simultaneously bind all histones. We present a low-resolution cryo–electron microscopy structure of SMARCAD1 in complex with a nucleosome and show that the adenosine triphosphatase domains engage their substrate unlike any other chromatin remodeler. Our biochemical and structural data provide mechanistic insights into SMARCAD1-induced nucleosome disassembly and reassembly.

SMARCAD1-mediated active replication fork stability maintains genome integrity

The stalled fork protection pathway mediated by breast cancer 1/2 (BRCA1/2) proteins is critical for replication fork stability. However, it is unclear whether additional mechanisms are required to maintain replication fork stability. We describe a hitherto unknown mechanism, by which the SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily-A containing DEAD/H box-1 (SMARCAD1) stabilizes active replication forks, that is essential to maintaining resistance towards replication poisons. We find that SMARCAD1 prevents accumulation of 53BP1-associated nucleosomes to preclude toxic enrichment of 53BP1 at the forks. In the absence of SMARCAD1, 53BP1 mediates untimely dissociation of PCNA via the PCNA-unloader ATAD5, causing frequent fork stalling, inefficient fork restart, and accumulation of single-stranded DNA. Although loss of 53BP1 in SMARCAD1 mutants rescues these defects and restores genome stability, this rescued stabilization also requires BRCA1-mediated fork protection. Notably, fork protection-challenged BRCA1-deficient naïve- or chemoresistant tumors require SMARCAD1-mediated active fork stabilization to maintain unperturbed fork progression and cellular proliferation.

Long non-coding RNAs: the tentacles of chromatin remodeler complexes

Chromatin remodeler complexes regulate gene transcription, DNA replication and DNA repair by changing both nucleosome position and post-translational modifications. The chromatin remodeler complexes are categorized into four families: the SWI/SNF, INO80/SWR1, ISWI and CHD family. In this review, we describe the subunits of these chromatin remodeler complexes, in particular, the recently identified members of the ISWI family and novelties of the CHD family. Long non-coding (lnc) RNAs regulate gene expression through different epigenetic mechanisms, including interaction with chromatin remodelers. For example, interaction of lncBRM with BRM inhibits the SWI/SNF complex associated with a differentiated phenotype and favors assembly of a stem cell-related SWI/SNF complex. Today, over 50 lncRNAs have been shown to affect chromatin remodeler complexes and we here discuss the mechanisms involved.

The Mechanism of Chromatin Remodeler SMARCAD1/Fun30 in Response to DNA Damage

DNA packs into highly condensed chromatin to organize the genome in eukaryotes but occludes many regulatory DNA elements. Access to DNA within nucleosomes is therefore required for a variety of biological processes in cells including transcription, replication, and DNA repair. To cope with this problem, cells employ a set of specialized ATP-dependent chromatin-remodeling protein complexes to enable dynamic access to packaged DNA. In the present review, we summarize the recent advances in the functional and mechanistic studies on a particular chromatin remodeler SMARCAD1^Fun30 which has been demonstrated to play a key role in distinct cellular processes and gained much attention in recent years. Focus is given to how SMARCAD1^Fun30 regulates various cellular processes through its chromatin remodeling activity, and especially the regulatory role of SMARCAD1^Fun30 in gene expression control, maintenance and establishment of heterochromatin, and DNA damage repair. Moreover, we review the studies on the molecular mechanism of SMARCAD1^Fun30 that promotes the DNA end-resection on double-strand break ends, including the mechanisms of recruitment, activity regulation and chromatin remodeling.

An embryonic stem cell-specific heterochromatin state promotes core histone exchange in the absence of DNA accessibility

Nucleosome turnover concomitant with incorporation of the replication-independent histone variant H3.3 is a hallmark of regulatory regions in the animal genome. Nucleosome turnover is known to be universally linked to DNA accessibility and histone acetylation. In mouse embryonic stem cells, H3.3 is also highly enriched at interstitial heterochromatin, most prominently at intracisternal A-particle endogenous retroviral elements. Interstitial heterochromatin is established over confined domains by the TRIM28-KAP1/SETDB1 corepressor complex and has stereotypical features of repressive chromatin, such as H3K9me3 and recruitment of all HP1 isoforms. Here, we demonstrate that fast histone turnover and H3.3 incorporation is compatible with these hallmarks of heterochromatin. Further, we find that Smarcad1 chromatin remodeler evicts nucleosomes generating accessible DNA. Free DNA is repackaged via DAXX-mediated nucleosome assembly with histone variant H3.3 in this dynamic heterochromatin state. Loss of H3.3 in mouse embryonic stem cells elicits a highly specific opening of interstitial heterochromatin with minimal effects on other silent or active regions of the genome.

Nucleosome turnover concomitant with incorporation of the histone variant H3.3 is a hallmark of regulatory regions in the animal genome. Here, the authors demonstrate that fast histone turnover and H3.3 incorporation defines a dynamic heterochromatin state in pluripotent stem cells.

Silencing and Transcriptional Regulation of Endogenous Retroviruses: An Overview

Almost half of the human genome is made up of transposable elements (TEs), and about 8% consists of endogenous retroviruses (ERVs). ERVs are remnants of ancient exogenous retrovirus infections of the germ line. Most TEs are inactive and not detrimental to the host. They are tightly regulated to ensure genomic stability of the host and avoid deregulation of nearby gene loci. Histone-based posttranslational modifications such as H3K9 trimethylation are one of the main silencing mechanisms. Trim28 is one of the identified master regulators of silencing, which recruits most prominently the H3K9 methyltransferase Setdb1, among other factors. Sumoylation and ATP-dependent chromatin remodeling factors seem to contribute to proper localization of Trim28 to ERV sequences and promote Trim28 interaction with Setdb1. Additionally, DNA methylation as well as RNA-mediated targeting of TEs such as piRNA-based silencing play important roles in ERV regulation. Despite the involvement of ERV overexpression in several cancer types, autoimmune diseases, and viral pathologies, ERVs are now also appreciated for their potential positive role in evolution. ERVs can provide new regulatory gene elements or novel binding sites for transcription factors, and ERV gene products can even be repurposed for the benefit of the host.

The 'dark matter' of ubiquitin-mediated processes: opportunities and challenges in the identification of ubiquitin-binding domains

Ubiquitin modifications of target proteins act to localise, direct and specify a diverse range of cellular processes, many of which are biomedically relevant. To allow this diversity, ubiquitin modifications exhibit remarkable complexity, determined by a combination of polyubiquitin chain length, linkage type, numbers of ubiquitin chains per target, and decoration of ubiquitin with other small modifiers. However, many questions remain about how different ubiquitin signals are specifically recognised and transduced by the decoding ubiquitin-binding domains (UBDs) within ubiquitin-binding proteins. This review briefly outlines our current knowledge surrounding the diversity of UBDs, identifies key challenges in their discovery and considers recent structural studies with implications for the increasing complexity of UBD function and identification. Given the comparatively low numbers of functionally characterised polyubiquitin-selective UBDs relative to the ever-expanding variety of polyubiquitin modifications, it is possible that many UBDs have been overlooked, in part due to limitations of current approaches used to predict their presence within the proteome. Potential experimental approaches for UBD discovery are considered; web-based informatic analyses, Next-Generation Phage Display, deubiquitinase-resistant diubiquitin, proximity-dependent biotinylation and Ubiquitin-Phototrap, including possible advantages and limitations. The concepts discussed here work towards identifying new UBDs which may represent the 'dark matter' of the ubiquitin system.

Nucleosome Remodeling by Fun30SMARCAD1 in the DNA Damage Response

Many cellular pathways are dedicated to maintain the integrity of the genome. In eukaryotes, the underlying DNA transactions occur in the context of chromatin. Cells utilize chromatin and its dynamic nature to regulate those genome integrity pathways. Accordingly, chromatin becomes restructured and modified around DNA damage sites. Here, we review the current knowledge of a chromatin remodeler Fun30^SMARCAD1, which plays a key role in genome maintenance. Fun30^SMARCAD1 promotes DNA end resection and the repair of DNA double-stranded breaks (DSBs). Notably, however, Fun30^SMARCAD1 plays additional roles in maintaining heterochromatin and promoting transcription. Overall, Fun30^SMARCAD1 is involved in distinct processes and the specific roles of Fun30^SMARCAD1 at DSBs, replication forks and sites of transcription appear discordant at first view. Nonetheless, a picture emerges in which commonalities within these context-dependent roles of Fun30^SMARCAD1 exist, which may help to gain a more global understanding of chromatin alterations induced by Fun30^SMARCAD1.

Moving Mountains-The BRCA1 Promotion of DNA Resection

DNA double-strand breaks (DSBs) occur in our cells in the context of chromatin. This type of lesion is toxic, entirely preventing genome continuity and causing cell death or terminal arrest. Several repair mechanisms can act on DNA surrounding a DSB, only some of which carry a low risk of mutation, so that which repair process is utilized is critical to the stability of genetic material of cells. A key component of repair outcome is the degree of DNA resection directed to either side of the break site. This in turn determines the subsequent forms of repair in which DNA homology plays a part. Here we will focus on chromatin and chromatin-bound complexes which constitute the "mountains" that block resection, with a particular focus on how the breast and ovarian cancer predisposition protein-1 (BRCA1) contributes to repair outcomes through overcoming these blocks.

A Ubiquitin-Binding Domain that Binds a Structural Fold Distinct from that of Ubiquitin

Ubiquitylation, the posttranslational linkage of ubiquitin moieties to lysines in target proteins, helps regulate a myriad of biological processes. Ubiquitin, and sometimes ubiquitin-homology domains, are recognized by ubiquitin-binding domains, including CUE domains. CUE domains are thus generally thought to function by mediating interactions with ubiquitylated proteins. The chromatin remodeler, SMARCAD1, interacts with KAP1, a transcriptional corepressor. The SMARCAD1-KAP1 interaction is direct and involves the first SMARCAD1 CUE domain (CUE1) and the RBCC domain of KAP1. Here, we present a structural model of the KAP1 RBCC-SMARCAD1 CUE1 complex based on X-ray crystallography. Remarkably, CUE1, a canonical CUE domain, recognizes a cluster of exposed hydrophobic and surrounding charged/amphipathic residues on KAP1, which are presented in the context of a coiled-coil domain, not in a structure resembling ubiquitin. Together, these data suggest that CUE domains may have a wider function than simply recognizing ubiquitin and the ubiquitin-fold.

SMARCAD1 ATPase activity is required to silence endogenous retroviruses in embryonic stem cells

Endogenous retroviruses (ERVs) can confer benefits to their host but present a threat to genome integrity if not regulated correctly. Here we identify the SWI/SNF-like remodeler SMARCAD1 as a key factor in the control of ERVs in embryonic stem cells. SMARCAD1 is enriched at ERV subfamilies class I and II, particularly at active intracisternal A-type particles (IAPs), where it preserves repressive histone methylation marks. Depletion of SMARCAD1 results in de-repression of IAPs and adjacent genes. Recruitment of SMARCAD1 to ERVs is dependent on KAP1, a central component of the silencing machinery. SMARCAD1 and KAP1 occupancy at ERVs is co-dependent and requires the ATPase function of SMARCAD1. Our findings uncover a role for the enzymatic activity of SMARCAD1 in cooperating with KAP1 to silence ERVs. This reveals ATP-dependent chromatin remodeling as an integral step in retrotransposon regulation in stem cells and advances our understanding of the mechanisms driving heterochromatin establishment.

Tight regulation of retrotransposons such as endogenous retroviruses (ERVs) is essential for genome and transcriptome integrity. Here, the authors show that the ATPase function of the chromatin remodeler SMARCAD1 facilitates the binding of KAP1 to ERVs and is required for their repression in embryonic stem cells.

SMARCAD1 Promotes Pancreatic Cancer Cell Growth and Metastasis through Wnt/β-catenin-Mediated EMT

Pancreatic cancer (PC) is one of the most lethal diseases, characterized by early metastasis and high mortality. Subunits of the SWI/SNF complex have been identified in many studies as the regulators of tumor progression, but the role of SMARCAD1, one member of the SWI/SNF family, in pancreatic cancer has not been elucidated. Based on analysis of GEO database and immunohistochemical detection of patient-derived pancreatic cancer tissues, we found that SMARCAD1 is more highly expressed in pancreatic cancer tissues and that its expression level negatively correlates with patients' survival time. With further investigation, it shows that SMARCAD1 promotes the proliferation, migration, invasion of pancreatic cancer cells. Mechanistically, we first demonstrate that SMARCAD1 induces EMT via activating Wnt/β-catenin signaling pathway in pancreatic cancer. Our results provide the role and potential mechanism of SMARCAD1 in pancreatic cancer, which may prove useful marker for diagnostic or therapeutic applications of PC disease.