Biology subjects

Henikoff, S.

Publications and source records attributed to Henikoff, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Elevated polyadenylated histone gene transcription in human cancer

Histone production is tightly restricted to S-phase to prevent genomic instability, yet human cancers with an overabundance of RNA Polymerase II (RNAPII) at histone genes are associated with aggressive cancers. To better understand histone gene overexpression in cancer, we applied a quantitative PCR assay to measure total replication-coupled histone output across the histone gene clusters using cell line models. We observed pervasive accumulation of polyadenylated histone transcripts, supported by analysis of >1,400 RNA-sequencing datasets in human cancers, with more than 70% of patients showing tumor specific increases. This alternative processing preferentially enriches for histone H2B, which lacks replication independent variants, across >8,300 tumors comprising diverse cancer types and transcriptional subtypes. We also found that disruption of nuclear components required to maintain RNAPII levels at the histone genes increased polyadenylated histone transcripts. Our results suggest that S-phase-dependent histone genes are subject to unscheduled gap phase transcription in human cancer.

cancer biology↗

bioRxiv2026

FFPE-CUTAC: A Single Assay, Multiple Layers

Background: Archival biobanks of formalin-fixed paraffin-embedded (FFPE) specimens represent a vast and underused resource for retrospective molecular studies linked to clinical follow-up. However, fixation-induced chemical modification and nucleic acid fragmentation limit scalable genomic and transcriptomic profiling. FFPE-CUTAC (Cleavage Under Targeted Accessible Chromatin) is an RNA polymerase II-targeted DNA assay specifically designed to profile regulatory activity in FFPE tissue. Here, we assess its archival robustness, information content, compatibility with RNA-seq, and ability to recover copy-number alterations. Results: In meningioma and breast cancer cohorts, we benchmarked FFPE-CUTAC against matched fresh-frozen RNA-seq, FFPE RNA-seq and FFPE whole-genome sequencing. For FFPE specimens spanning up to 25 years, FFPE-CUTAC showed no systematic collection-year-associated decline in library yield or signal-quality metrics. In contrast, FFPE RNA-seq is more affected by the FFPE tissue degradation and specimen age on read composition, gene-body coverage, and gene detection. By measuring RNA polymerase II occupancy on chromatin rather than mature RNA abundance, FFPE-CUTAC is less constrained by transcript half-life, polyadenylation or transcript-capture design. FFPE-CUTAC extends beyond gene regions to non-coding regulatory elements, while the shared gene-level signals supported its integration with existing RNA-seq cohorts for large-scale, long-term clinical association study. FFPE-CUTAC libraries also retain DNA dosage information and can be used to recover chromosome-arm gain, loss and intact states with 96% concordance to matched whole-genome sequencing. Conclusions: By converting routinely preserved pathology sections into integrated regulatory and copy-number profiles, FFPE-CUTAC provides a practical foundation for constructing clinically annotated disease maps to support molecular stratification, prognostic modeling and treatment-association studies.

cancer biology↗

bioRxiv2026

BAF perturbation augments cancer cell dependence on CDK12-driven transcription elongation by RNA polymerase II

CDK12 facilitates transcriptional elongation and processivity by RNA polymerase II (Pol II). Although it has emerged as a promising actor and target in cancer, better understanding of CDK12 gene transcription control could inform the design of novel anti-cancer strategies. Here, we identify a co-dependency between CDK12 and the BAF chromatin-remodeling complex in triple-negative breast cancer (TNBC). Genome-scale CRISPR interference screening revealed multiple BAF subunits as strong dependencies upon CDK12 inhibition. In turn, pharmacological co-targeting of CDK12 and BAF ATPase synergistically reduced the viability of multiple TNBC models. Mechanistically, the co-inhibition attenuated di-phosphorylation of the Pol II C-terminal domain at Serine-2 and Serine-5 and depleted canonical pre-mRNA 3'-end processing factors from chromatin, driving accumulation of chromatin-associated Pol II, upstream of apoptosis. Whereas BAF inhibition rapidly reduced transcription-coupled DNA accessibility, CDK12 inhibition imposed a gene length-biased transcriptional defect exacerbated by BAF deficiency. In turn, co-inhibited cells, marked by synergistic induction of MYC and repression of long cell-cycle and mitotic genes, showed a failure of DNA synthesis and mitotic entry, culminating in MYC-mediated apoptosis. Together, our findings reveal a regulatory axis in which impaired Pol II elongation creates a heightened requirement for BAF-dependent chromatin remodeling. This discovered co-dependency provides a rationale for co-targeting the CDK12-BAF axis in transcriptionally addicted cancers.

molecular biology↗

bioRxiv2026

Aclarubicin disrupts RNA polymerase II progression at replication-coupled histone genes

Anthracyclines are highly effective chemotherapeutic agents that cause DNA and chromatin damage. One member of the anthracyclines, aclarubicin, has recently gained therapeutic interest due to its ability to kill cancer cells through chromatin-based mechanisms, thus avoiding the off-target effects associated with DNA damage. Despite this, the molecular mechanism of action leading to aclarubicin-induced chromatin damage remains elusive. Here we performed Cleavage Under Targets and Tagmentation (CUT&Tag) of RNA polymerase II (Pol II) and other transcriptional regulators in human cells during aclarubicin treatment. We found that aclarubicin strongly disrupts the replication-coupled histone genes, resulting in a nonproductive accumulation of Pol II-transcription machinery here beyond the levels at other genes. We attribute this sensitivity to the dense Pol II loading and rapid transcription of the histone genes, which intensify the chromatin-disrupting effects of aclarubicin at these loci. Together, our findings support the effectiveness of aclarubicin as an anticancer drug and point to the histone gene cluster as a promising target for therapeutic intervention.

molecular biology↗

bioRxiv2026

KAS-CUT&Tag for direct mapping of transcription bubbles

Transcription by RNA Polymerase II (Pol II) generates dynamic transcription bubbles as it moves forward, but existing methods map transcriptional activity in vivo only indirectly. We introduce KAS-CUT&Tag, a method that combines N3-kethoxal labeling of exposed guanines with CUT&Tag to directly map transcription bubbles. We find that bubble density varies across Pol II-bound genes at transcription start sites, gene bodies, and termination sites. Transcription bubbles are enriched at genes marked by the H3K36me3 histone modification and chromatin-bound splicing factor U2AF2, but the highest enrichment is at replication-coupled histone genes throughout the cell cycle. KAS-CUT&Tag also detects colocalization of the histone gene transcription factor NPAT with Pol II at the Histone Locus Body, suggesting NPAT is juxtaposed to transcription bubbles via interaction with Pol II. Together, KAS-CUT&Tag enables direct mapping of Pol II and regulatory interactions at transcription bubbles, providing a powerful tool for precise analysis of transcriptional activity.

genomics↗

bioRxiv2026

Histone H3K27 methylation states are sequentially catalyzed in cycling cells

Polycomb domains form at silenced genes and are marked by histone H3 lysine 27 tri-methylation, but it is unclear how this methylation is maintained following DNA replication in proliferating cells. Here, we use CUT&Tag chromatin profiling to track the dynamics of H3K27 methylation in human cells. We find that tri-methylation in Polycomb domains is maintained by stepwise methylation after DNA replication. Outside of Polycomb domains, thousands of inactive genes gain histone H3K27 di-methylation hours after DNA replication. Acute treatment with small-molecule inhibitors of the Polycomb Repressive Complex 2 (PRC2) histone methyltransferase slows H3K27 methylation during S-phase of the cell cycle and increases acetylation of the residue. This effect is most pronounced at Polycomb domains replicating in early S-phase, suggesting that early replication and slow histone methylation confers plasticity to developmentally silenced genes. Together, our results explain how H3K27 modification patterns are faithfully duplicated in rapidly proliferating cells.

genomics↗

bioRxiv2025

Chromatin profiling for everyone: FFPE-CUTAC for the theory and practice of modern molecular biology

In 2025, together with the Fred Hutch Summer Undergraduate Research and Summer High School Internship programs, we developed and implemented a laboratory genomics research experience to introduce students to modern molecular biology techniques and bioinformatics. The course centered around using a new method we had developed in 2023 that uses readily available fixed tissue sections on glass slides. Students performed a series of steps to tagment genomic locations of RNA Polymerase II and then used PCR to enrich libraries for next-generation sequencing in a core facility. Students then visualized their data in genomic browser tracks and assessed the results. At the end of the summer, students prepared and presented their work and experiences in seminar format to their cohorts. Overall, the technical simplicity of on-slide chromatin profiling introduced the students to laboratory practice and current techniques in genomics, bioinformatics, and medical sciences.

scientific communication and education↗

bioRxiv2025

Superabundant microRNAs are transcribed from human rDNA spacer promoters insulated by CTCF

MicroRNAs are [~]22-nucleotide RNAs processed from primary transcripts and exported from the nucleus to repress gene expression by base-pairing to mRNAs. We find that the highest levels of RNA Polymerase II at human microRNA genes are within the ribosomal gene repeat arrays (rDNAs). Alignment of public nascent transcript data to the hs1 human genome assembly reveals a 50-nucleotide transcript for both miR-1275 and miR-6724, which exits from the nucleus with exceptional rapidity. We show that the miR-1275/miR-6724 transcription unit is closely flanked by CCCTC-binding factor (CTCF) within a <400-bp span of the rDNA spacer promoter. MiR-1275/miR-6724 and microRNA precursors expressed from the 5 External Transcribed Spacer (5ETS) are exported independently of known RNA processing activities and are detected in exosomes and as circulating cancer biomarkers. We propose that rDNA spacer promoter and 5ETS microRNA genes have evolved for general regulatory functions in recipient cells.

genomics↗

bioRxiv2025

Nascent CUT&Tag captures transcription factor binding after chromatin duplication

DNA replication strips off all chromatin proteins, which must be reassembled behind the replication fork. To track chromatin reassembly on newly synthesized DNA, we developed Nascent CUT&Tag, a chromatin profiling method that directly measures transcription factor (TF) binding on nascent chromatin. We tracked the recovery of GAGA factor (GAF) and Pleiohomeotic (PHO) in Drosophila Kc167 cells. Whereas both TFs are evicted following passage of the replication fork, GAF recovers on newly synthesized DNA over a minutes-to-hours range, whereas PHO generally requires hours to fully reestablish binding. Early recovering GAF peaks are characterized by shorter GAF motifs and are associated with functions related to cell cycle progression. Conversely, late recovering peaks are characterized by longer, degenerate GAF motifs and are associated with developmental functions. GAF recovery on newly synthesized DNA requires chromatin remodeling by Brahma Associated Factor (BAF), implying that nucleosome turnover is critical to fully reestablish GAF binding.

genomics↗

bioRxiv2025

CUT&TIME captures the history of open chromatin indeveloping neurons

Chromatin structure plays a central role in defining cell identity by regulating gene expression. During development, shifts in chromatin structure facilitate changes in gene expression needed to specify distinct cell types. To understand how changes in chromatin structure influence the developmental trajectory of neural progenitor cells, we developed CUT&TIME, a technique that uses a hyperactive 6-methyl adenosine (6mA) methyltransferase pulsed in living cells to map historical chromatin accessibility genome-wide in single cells. We show that CUT&TIME produces a record of the chromatin landscape during neurogenesis in the developing retina, specifically as neural progenitors produce the major projection neuron type, retinal ganglion cells (RGCs). We further show that this method is compatible with single cell profiling technologies, which allows us to visualize and capture the diversity of chromatin states that produce RGCs. Additionally, we identify changes in promoter accessibility associated with the transition from progenitor to RGC. Together, these data demonstrate that CUT&TIME captures a historical record of chromatin structure, which can be used to identify early changes in accessibility associated with cell-fate commitment.

developmental biology↗

bioRxiv2025

Total whole-arm chromosome losses predict malignancy in human cancer

Aneuploidy is observed as gains or losses of whole chromosomes or chromosome arms and is a common hallmark of cancer. Whereas models for the generation of aneuploidy in cancer invoke mitotic chromosome segregation errors, whole-arm losses might occur simply as a result of centromere breakage. We recently showed that elevated RNA Polymerase II (RNAPII) level over S-phase-dependent histone genes predicts rapid recurrence of human meningioma and is correlated with total whole-arm losses relative to gains. To explain this imbalance in arm losses over gains, we have proposed that histone overexpression at S-phase competes with the histone H3 variant CENP-A, resulting in centromere breaks and whole-arm losses. To test whether centromere breaks alone can drive aneuploidy, we ask whether total whole-arm aneuploids can predict outcome across different cancer types in large RNA and whole-genome sequencing databanks. We find that total whole-arm losses generally predict outcome, suggesting that centromere breakage is a major initiating factor leading to aneuploidy and the resulting changes in the selective landscape that drive most cancers. We also present evidence that centromere breakage alone is sufficient to account for whole-arm losses and gains, contrary to mitotic spindle error models for generation of aneuploidy. Our results suggest that therapeutic intervention targeting histone overexpression has the potential of reducing aneuploidy and slowing cancer progression. Significance StatementGain or loss of whole chromosome arms following centromere breaks is frequent in cancer, but whether or not there is a common initiating event is unknown. Here we show that the total number of whole-arm losses predicts patient outcomes across cancer types, suggesting a causal relationship. This general excess of losses over gains is not predicted by mitotic error models of aneuploidy but rather suggests that centromere breaks themselves initiate whole-arm aneuploidies. Insofar as aneuploidy reshapes the selective landscapes that drive most cancers, our results have potential clinical implications.

cancer biology↗

bioRxiv2024

Histone H4 limits transcription of the histone locus in Drosophila

In all eukaryotes DNA replication is coupled to histone synthesis to coordinate chromatin packaging of the genome. Canonical histone genes coalesce in the nucleus into the Histone Locus Body (HLB), where gene transcription and 3 mRNA processing occurs. Both histone gene transcription and mRNA stability are reduced when DNA replication is inhibited, implying that the Histone Locus Body senses the rate of DNA synthesis. In Drosophila melanogaster, the S-phase-induced histone genes are tandemly repeated in an [~]100 copy array, whereas in humans, these histone genes are scattered. In both organisms these genes coalesce into Histone Locus Bodies. We used a transgenic histone gene reporter and RNAi in Drosophila to identify canonical H4 histone as a unique repressor of histone synthesis during the G2 phase in germline cells. Using cytology and CUT&Tag chromatin profiling, we find that histone H4 uniquely occupies histone gene promoters in both Drosophila and human cells. Our results suggest that repression of histone genes by soluble histone H4 is a conserved mechanism that coordinates DNA replication with histone synthesis in proliferating cells.

genomics↗

bioRxiv2024

An integrated view of the structure and function of the human 4D nucleome

The dynamic three-dimensional (3D) organization of the human genome (the "4D Nucleome") is closely linked to genome function. Here, we integrate a wide variety of genomic data generated by the 4D Nucleome Project to provide a detailed view of human 3D genome organization in widely used embryonic stem cells (H1-hESCs) and immortalized fibroblasts (HFFc6). We provide extensive benchmarking of 3D genome mapping assays and integrate these diverse datasets to annotate spatial genomic features across scales. The data reveal a rich complexity of chromatin domains and their sub-nuclear positions, and over one hundred thousand structural loops and promoter-enhancer interactions. We developed 3D models of population-based and individual cell-to-cell variation in genome structure, establishing connections between chromosome folding, nuclear organization, chromatin looping, gene transcription, and DNA replication. We demonstrate the use of computational methods to predict genome folding from DNA sequence, uncovering potential effects of genetic variants on genome structure and function. Together, this comprehensive analysis contributes insights into human genome organization and enhances our understanding of connections between the regulation of genome function and 3D genome organization in general.

genomics↗

bioRxiv2024

Direct measurement of RNA Polymerase II hypertranscription in cancer FFPE samples

Genome-wide hypertranscription is common in hu-man cancer and predicts poor prognosis. To under-stand how hypertranscription might drive cancer, we applied our FFPE-CUTAC method for mapping RNA Polymerase II (RNAPII) genome-wide in formalin-fixed paraffin-embedded (FFPE) sections. We demonstrate global RNAPII elevations in mouse gliomas and assort-ed human tumors in small clinical samples and discov-er regional elevations corresponding to de novo HER2 amplifications punctuated by likely selective sweeps. RNAPII occupancy at replication-coupled histone genes correlated with WHO grade in meningiomas, ac-curately predicted rapid recurrence, and corresponded to whole-arm chromosome losses. Elevated RNAPII at histone genes in meningiomas and diverse breast cancers is consistent with histone production being rate-limiting for S-phase progression and histone gene hypertranscription driving overproliferation and aneu-ploidy in cancer, with general implications for precision oncology.

cancer biology↗

bioRxiv2023

KMT2A oncoproteins induce epigenetic resistance to targeted therapies

Chromosomal translocations involving the Lysine-Methyl-Transferase-2A (KMT2A) locus generate potent oncogenic fusion proteins (oncoproteins) that disrupt regulation of developmental gene expression. By profiling the oncoprotein-target sites of 36 broadly representative KMT2A-rearranged leukemia samples, including three samples that underwent a lymphoid-to-myeloid lineage-switching event in response to therapy, we find the genomic enrichment of the oncoprotein is highly variable between samples and subject to dynamic regulation. At high levels of expression, the oncoproteins preferentially activate either an acute lymphoblastic leukemia (ALL) program, enriched for pro-B-cell genes, or an acute myeloid leukemia (AML) program, enriched for hematopoietic-stem-cell genes. The fusion-partner-specific-binding patterns over these gene sets are highly correlated with the prevalence of each mutation in ALL versus AML. In lineage-switching samples the oncoprotein levels are reduced and the oncoproteins preferentially activate granulocyte-monocyte progenitor (GMP) genes. In a sample that lineage switched during treatment with the menin inhibitor revumenib, the oncoprotein and menin are reduced to undetectable levels, but ENL, a transcriptional cofactor of the oncoprotein, persists on numerous oncoprotein-target loci, including genes in the GMP-like lineage-switching program. We propose KMT2A oncoproteins promote lineage-switching events through dynamic chromatin binding and can induce epigenetic lesions, marked by ENL, that support resistance to targeted therapies.

cancer biology↗

bioRxiv2023

Expansion of human centromeric arrays in cells undergoing break-induced replication

Human centromeres are located within -satellite arrays and evolve rapidly, which can lead to individual variation in array lengths. Proposed mechanisms for such alterations in lengths are unequal cross-over between sister chromatids, gene conversion, and break-induced replication. However, the underlying molecular mechanisms responsible for the massive, complex, and homogeneous organization of centromeric arrays have not been experimentally validated. Here, we use droplet digital PCR assays to demonstrate that centromeric arrays can expand and contract within ~20 somatic cell divisions of a cell line. We find that the frequency of array variation among single-cell-derived subclones ranges from a minimum of ~7% to a maximum of ~100%. Further clonal evolution revealed that centromere expansion is favored over contraction. We find that the homologous recombination protein RAD52 and the helicase PIF1 are required for extensive array change, suggesting that centromere sequence evolution can occur via break-induced replication.

genetics↗

bioRxiv2023

Chromatin Profiling of CBFA2T3-GLIS2 AMLs Identifies Key Transcription Factor Dependencies and BRG1 Inhibition as a Novel Therapeutic Strategy

Oncogenic fusions involving transcription factors are present in the majority of pediatric leukemias; however, the context-specific mechanisms they employ to drive cancer remain poorly understood. CBFA2T3-GLIS2 (C/G) fusions occur in treatment-refractory acute myeloid leukemias and are restricted to young children. To understand how the C/G fusion drives oncogenesis we applied CUT&RUN chromatin profiling to an umbilical cord blood/endothelial cell (EC) co-culture model of C/G AML that recapitulates the biology of this malignancy. We find C/G fusion binding is mediated by its zinc finger domains. Integration of fusion binding sites in C/G- transduced cells with Polycomb Repressive Complex 2 (PRC2) sites in control cord blood cells identifies MYCN, ZFPM1, ZBTB16 and LMO2 as direct C/G targets. Transcriptomic analysis of a large pediatric AML cohort shows that these genes are upregulated in C/G patient samples. Single cell RNA-sequencing of umbilical cord blood identifies a population of megakaryocyte precursors that already express many of these genes despite lacking the fusion. By integrating CUT&RUN data with CRISPR dependency screens we identify BRG1/SMARCA4 as a vulnerability in C/G AML. BRG1 profiling in C/G patient-derived cell lines shows that the CBFA2T3 locus is a binding site, and treatment with clinically-available BRG1 inhibitors reduces fusion levels and downstream C/G targets including N-MYC, resulting in C/G leukemia cell death and extending survival in a murine xenograft model.

cancer biology↗

bioRxiv2023

Epigenomic analysis of Formalin-Fixed Paraffin-Embedded samples by CUT&Tag

For more than a century, Formalin Fixed Paraffin Embedded (FFPE) sample preparation has been the preferred method for long-term preservation of biological material. However, the use of FFPE samples for epigenomic studies has been difficult because of chromatin damage from long exposure to high concentrations of formaldehyde. Previously, we introduced Cleavage Under Targeted Accessible Chromatin (CUTAC), an antibody-targeted chromatin accessibility mapping protocol based on CUT&Tag. Here we show that simple modifications of our single-tube CUTAC protocol are sufficient to produce high-resolution maps of paused RNA Polymerase II (RNAPII) at enhancers and promoters using FFPE samples. We find that transcriptional regulatory element differences produced by FFPE-CUTAC distinguish between mouse brain tumor specimens and identify regulatory element markers with high confidence and precision. Our simple work-flow is suitable for automation, making possible affordable epigenomic profiling of archived biological samples for biomarker identification, clinical applications and retrospective studies.

cancer biology↗