Regulation of condensin II by self-suppression and release mechanisms.

In vertebrates, two distinct condensin complexes, condensin I and condensin II, cooperate to drive mitotic chromosome assembly. It remains largely unknown how the two complexes differentially contribute to this process at a mechanistic level. We have previously dissected the role of individual subunits of condensin II by introducing recombinant complexes into Xenopus egg extracts. Here we extend these efforts by introducing a modified functional assay using extracts depleted of topoisomerase IIα (topo IIα), which allows us to further elucidate the functional similarities and differences between condensin I and condensin II. The intrinsically disordered C-terminal region of the CAP-D3 subunit (the D3 C-tail) is a major target of Cdk1 phosphorylation, and phosphorylation-deficient mutations in this region impair condensin II functions. We also identify a unique helical structure in CAP-D3 (the D3 HEAT docker) that is predicted to directly interact with CAP-G2. Deletion of the D3 HEAT docker, along with the D3 C-tail, enhances the ability of condensin II to assemble mitotic chromosomes. Taken together, we propose a self-suppression mechanism unique to condensin II that is released by mitotic phosphorylation. Evolutionary implications of our findings are also discussed.

KMT2C methyltransferase domain regulated INK4A expression suppresses prostate cancer metastasis.

BACKGROUND: Frequent truncation mutations of the histone lysine N-methyltransferase KMT2C have been detected by whole exome sequencing studies in various cancers, including malignancies of the prostate. However, the biological consequences of these alterations in prostate cancer have not yet been elucidated. METHODS: To investigate the functional effects of these mutations, we deleted the C-terminal catalytic core motif of Kmt2c specifically in mouse prostate epithelium. We analysed the effect of Kmt2c SET domain deletion in a Pten-deficient PCa mouse model in vivo and of truncation mutations of KMT2C in a large number of prostate cancer patients. RESULTS: We show here for the first time that impaired KMT2C methyltransferase activity drives proliferation and PIN formation and, when combined with loss of the tumour suppressor PTEN, triggers loss of senescence, metastatic dissemination and dramatically reduces life expectancy. In Kmt2c-mutated tumours we show enrichment of proliferative MYC gene signatures and loss of expression of the cell cycle repressor p16INK4A. In addition, we observe a striking reduction in disease-free survival of patients with KMT2C-mutated prostate cancer. CONCLUSIONS: We identified truncating events of KMT2C as drivers of proliferation and PIN formation. Loss of PTEN and KMT2C in prostate cancer results in loss of senescence, metastatic dissemination and reduced life expectancy. Our data demonstrate the prognostic significance of KMT2C mutation status in prostate cancer patients. Inhibition of the MYC signalling axis may be a viable treatment option for patients with KMT2C truncations and therefore poor prognosis.

Thrap3 promotes osteogenesis by inhibiting the degradation of Runx2.

The dysfunction of osteogenesis is a key character in the pathogenesis of osteoporosis, but the network of signaling mechanisms in controlling the differentiation of osteoblast remain unclear. Thrap3 has been proved participating in various biological process, especially in the differentiation of stem cells. Here, we demonstrate that Thrap3 could promote osteogenesis through the inhibition of the degradation of Runx2, which is a key molecular structure in early osteoblast differentiation. Furthermore, we found that the osteogenesis enhancing capacity of Thrap3 was caused by physically binding with Sox9, inhibiting the transcriptional activity of Sox9, and then decreasing the decomposition-promoted effect of Sox9 on Runx2. Our data shows that Thrap3 promotes osteoblast differentiation through the Thrap3-Sox9-Runx2 axis. What we found may help for further clarifying the molecular mechanism of osteogenic differentiation and give a new potential therapeutic target for osteoporosis.

Lamina-associated polypeptide 2α is required for intranuclear MRTF-A activity.

Myocardin-related transcription factor A (MRTF-A), a coactivator of serum response factor (SRF), regulates the expression of many cytoskeletal genes in response to cytoplasmic and nuclear actin dynamics. Here we describe a novel mechanism to regulate MRTF-A activity within the nucleus by showing that lamina-associated polypeptide 2α (Lap2α), the nucleoplasmic isoform of Lap2, is a direct binding partner of MRTF-A, and required for the efficient expression of MRTF-A/SRF target genes. Mechanistically, Lap2α is not required for MRTF-A nuclear localization, unlike most other MRTF-A regulators, but is required for efficient recruitment of MRTF-A to its target genes. This regulatory step takes place prior to MRTF-A chromatin binding, because Lap2α neither interacts with, nor specifically influences active histone marks on MRTF-A/SRF target genes. Phenotypically, Lap2α is required for serum-induced cell migration, and deregulated MRTF-A activity may also contribute to muscle and proliferation phenotypes associated with loss of Lap2α. Our studies therefore add another regulatory layer to the control of MRTF-A-SRF-mediated gene expression, and broaden the role of Lap2α in transcriptional regulation.

A20 and ABIN-1 cooperate in balancing CBM complex-triggered NF-κB signaling in activated T cells.

T cell activation initiates protective adaptive immunity, but counterbalancing mechanisms are critical to prevent overshooting responses and to maintain immune homeostasis. The CARD11-BCL10-MALT1 (CBM) complex bridges T cell receptor engagement to NF-κB signaling and MALT1 protease activation. Here, we show that ABIN-1 is modulating the suppressive function of A20 in T cells. Using quantitative mass spectrometry, we identified ABIN-1 as an interactor of the CBM signalosome in activated T cells. A20 and ABIN-1 counteract inducible activation of human primary CD4 and Jurkat T cells. While A20 overexpression is able to silence CBM complex-triggered NF-κB and MALT1 protease activation independent of ABIN-1, the negative regulatory function of ABIN-1 depends on A20. The suppressive function of A20 in T cells relies on ubiquitin binding through the C-terminal zinc finger (ZnF)4/7 motifs, but does not involve the deubiquitinating activity of the OTU domain. Our mechanistic studies reveal that the A20/ABIN-1 module is recruited to the CBM complex via A20 ZnF4/7 and that proteasomal degradation of A20 and ABIN-1 releases the CBM complex from the negative impact of both regulators. Ubiquitin binding to A20 ZnF4/7 promotes destructive K48-polyubiquitination to itself and to ABIN-1. Further, after prolonged T cell stimulation, ABIN-1 antagonizes MALT1-catalyzed cleavage of re-synthesized A20 and thereby diminishes sustained CBM complex signaling. Taken together, interdependent post-translational mechanisms are tightly controlling expression and activity of the A20/ABIN-1 silencing module and the cooperative action of both negative regulators is critical to balance CBM complex signaling and T cell activation.

The Ets protein Pointed P1 represses Asense expression in type II neuroblasts by activating Tailless.

Intermediate neural progenitors (INPs) boost the number and diversity of neurons generated from neural stem cells (NSCs) by undergoing transient proliferation. In the developing Drosophila brains, INPs are generated from type II neuroblasts (NBs). In order to maintain type II NB identity and their capability to produce INPs, the proneural protein Asense (Ase) needs to be silenced by the Ets transcription factor pointed P1 (PntP1), a master regulator of type II NB development. However, the molecular mechanisms underlying the PntP1-mediated suppression of Ase is still unclear. In this study, we utilized genetic and molecular approaches to determine the transcriptional property of PntP1 and identify the direct downstream effector of PntP1 and the cis-DNA elements that mediate the suppression of ase. Our results demonstrate that PntP1 directly activates the expression of the transcriptional repressor, Tailless (Tll), by binding to seven Ets-binding sites, and Tll in turn suppresses the expression of Ase in type II NBs by binding to two hexameric core half-site motifs. We further show that Tll provides positive feedback to maintain the expression of PntP1 and the identity of type II NBs. Thus, our study identifies a novel direct target of PntP1 and reveals mechanistic details of the specification and maintenance of the type II NB identity by PntP1.

Long non-coding RNA MEG8 induced by PLAG1 promotes clear cell renal cell carcinoma through the miR-495-3p/G3BP1 axis.

Clear cell renal cell carcinoma (ccRCC) is recognized as one of the most lethal malignancies among the urological system, with constantly increasing mortality. While the molecular mechanisms underlying ccRCC progression are still poorly understood, the molecular and functional role of lncRNA in multiple diseases has been well demonstrated. In this study, we hypothesized that lncRNA MEG8 might participate in ccRCC development. At first, we found that MEG8 expression was increased in ccRCC tumor tissues and cells. Next, we demonstrated that MEG8 knockdown suppressed cell viability, migration, and invasion in vitro and inhibited tumor growth in vivo. Subsequently, we utilized bioinformatics analysis, ChIP, and luciferase assays, and we found that PLAG1 could transcriptionally regulate MEG8 in ccRCC cells. Furthermore, MEG8 promoted G3BP1 expression to aggravate ccRCC tumorigenic properties through sponging miR-495-3p. Our study identified a novel PLAG1/MEG8/miR-495-3p/G3BP1 network in ccRCC development, which might be a promising direction for developing new diagnoses or therapeutic agents for ccRCC.

Coordinated post-transcriptional control of oncogene-induced senescence by UNR/CSDE1.

Oncogene-induced senescence (OIS) is a form of stable cell-cycle arrest arising in response to oncogenic stimulation. OIS must be bypassed for transformation, but the mechanisms of OIS establishment and bypass remain poorly understood, especially at the post-transcriptional level. Here, we show that the RNA-binding protein UNR/CSDE1 enables OIS in primary mouse keratinocytes. Depletion of CSDE1 leads to senescence bypass, cell immortalization, and tumor formation, indicating that CSDE1 behaves as a tumor suppressor. Unbiased high-throughput analyses uncovered that CSDE1 promotes OIS by two independent molecular mechanisms: enhancement of the stability of senescence-associated secretory phenotype (SASP) factor mRNAs and repression of Ybx1 mRNA translation. Importantly, depletion of YBX1 from immortal keratinocytes rescues senescence and uncouples proliferation arrest from the SASP, revealing multilayered mechanisms exerted by CSDE1 to coordinate senescence. Our data highlight the relevance of post-transcriptional control in the regulation of senescence.

MicroRNA-543 inhibits the proliferation, migration, invasion, and epithelial-mesenchymal transition of triple-negative breast cancer cells via down-regulation of ACTL6A gene.

PURPOSE: To investigate the effect of microRNA-543 (miR-543) on the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of triple-negative breast cancer (TNBC) cells, and the associated mechanism. METHODS: Human breast cancer cells (MDA-MB-231, HCC1937, and MCF-7, ZR-75-1) and normal human breast epithelial cell line (MCF10A) were transfected with miR-543 mimics or inhibitor using lipofectamine 2000. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting were used to determine the mRNA and protein expression levels of miR-543, actin-like protein 6A (ACTL6A), vimentin, Snail, and E-cadherin in breast cancer cells/tissue. Cell counting kit-8 (CCK-8), wound-healing, and Transwell assays were used to measure the effect of miR-543 on TNBC cell proliferation, invasion, and migration. Overall survival was determined using data from Gene Expression Omnibus (GEO) and Cancer Genome Atlas (TCGA) databases. Bioinformatics analysis and luciferase reporter gene assay were used to determine the regulatory effect of miR-543 on ACTL6A. RESULTS: The level of expression of miR-543 was significantly lower in breast cancer cells/tissue than in normal human breast epithelial cell/tissue (p < 0.05). MicroRNA-543 expression level was significantly reduced in TNBC cells/tissue, relative to the other breast cancer cells/normal breast tissue (p < 0.05). MicroRNA-543 significantly suppressed tumor growth and the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of TNBC cells, in mouse xenograft model (p < 0.05). CONCLUSIONS: miR-543 influences the biological behavior of TNBC cells by directly targeting ACTL6A gene. miR-543 could serve as a novel diagnostic and therapeutic target for TNBC.

Loss of ARID1A activates mTOR signaling and SOX9 in gastric adenocarcinoma-rationale for targeting ARID1A deficiency.

BACKGROUND: Gastric adenocarcinoma (GAC) is a lethal disease with limited therapeutic options. Genetic alterations in chromatin remodelling gene AT-rich interactive domain 1A (ARID1A) and mTOR pathway activation occur frequently in GAC. Targeting the mechanistic target of rapamycin (mTOR) pathway in unselected patients has failed to show survival benefit. A deeper understanding of GAC might identify a subset that can benefit from mTOR inhibition. METHODS: Genomic alterations in ARID1A were analysed in GAC. Mouse gastric epithelial cells from CK19-Cre-Arid1Afl/fl and wild-type mice were used to determine the activation of oncogenic genes due to loss of Arid1A. Functional studies were performed to determine the significance of loss of ARID1A and the sensitivity of ARID1A-deficient cancer cells to mTOR inhibition in GAC. RESULTS: More than 30% of GAC cases had alterations (mutations or deletions) of ARID1A and ARID1A expression was negatively associated with phosphorylation of S6 and SOX9 in GAC tissues and patient-derived xenografts (PDXs). Activation of mTOR signalling (increased pS6) and SOX9 nuclear expression were strongly increased in Arid1A-/- mouse gastric tissues which could be curtailed by RAD001, an mTOR inhibitor. Knockdown of ARID1A in GAC cell lines increased pS6 and nuclear SOX9 and increased sensitivity to an mTOR inhibitor which was further amplified by its combination with fluorouracil both in vitro and in vivo in PDXs. CONCLUSIONS: The loss of ARID1A activates pS6 and SOX9 in GAC, which can be effectively targeted by an mTOR inhibitor. Therefore, our studies suggest a new therapeutic strategy of clinically targeting the mTOR pathway in patients with GAC with ARID1A deficiency.

Control of Foxp3 induction and maintenance by sequential histone acetylation and DNA demethylation.

Regulatory T (Treg) cells play crucial roles in suppressing deleterious immune response. Here, we investigate how Treg cells are mechanistically induced in vitro (iTreg) and stabilized via transcriptional regulation of Treg lineage-specifying factor Foxp3. We find that acetylation of histone tails at the Foxp3 promoter is required for inducing Foxp3 transcription. Upon induction, histone acetylation signals via bromodomain-containing proteins, particularly targets of inhibitor JQ1, and sustains Foxp3 transcription via a global or trans effect. Subsequently, Tet-mediated DNA demethylation of Foxp3 cis-regulatory elements, mainly enhancer CNS2, increases chromatin accessibility and protein binding, stabilizing Foxp3 transcription and obviating the need for the histone acetylation signal. These processes transform stochastic iTreg induction into a stable cell fate, with the former sensitive and the latter resistant to genetic and environmental perturbations. Thus, sequential histone acetylation and DNA demethylation in Foxp3 induction and maintenance reflect stepwise mechanical switches governing iTreg cell lineage specification.

High Expression of GSDMC Is Associated with Poor Survival in Kidney Clear Cell Cancer.

This study is aimed at exploring the potential role of GSDMC in kidney renal clear cell carcinoma (KIRC). We analyzed the expression of GSDMC in 33 types of cancers in TCGA database. The results showed that the expression of GSDMC was upregulated in most cancers. We found a significant association between high expression of GSDMC and shortened patient overall survival, progression-free survival, and disease-specific survival. In vitro experiments have shown that the expression of GSDMC was significantly elevated in KIRC cell lines. Moreover, decreased expression of GSDMC was significantly associated with decreased cell proliferation. In summary, we believe that this study provides valuable data supporting future clinical treatment.

Differentiation of fetal hematopoietic stem cells requires ARID4B to restrict autocrine KITLG/KIT-Src signaling.

Balance between the hematopoietic stem cell (HSC) duality to either possess self-renewal capacity or differentiate into multipotency progenitors (MPPs) is crucial for maintaining homeostasis of the hematopoietic stem/progenitor cell (HSPC) compartment. To retain the HSC self-renewal activity, KIT, a receptor tyrosine kinase, in HSCs is activated by its cognate ligand KITLG originating from niche cells. Here, we show that AT-rich interaction domain 4B (ARID4B) interferes with KITLG/KIT signaling, consequently allowing HSC differentiation. Conditional Arid4b knockout in mouse hematopoietic cells blocks fetal HSC differentiation, preventing hematopoiesis. Mechanistically, ARID4B-deficient HSCs self-express KITLG and overexpress KIT. As to downstream pathways of KITLG/KIT signaling, inhibition of Src family kinases rescues the HSC differentiation defect elicited by ARID4B loss. In summary, the intrinsic ARID4B-KITLG/KIT-Src axis is an HSPC regulatory program that enables the differentiation state, while KIT stimulation by KITLG from niche cells preserves the HSPC undifferentiated pool.

SUMO orchestrates multiple alternative DNA-protein crosslink repair pathways.

Endogenous metabolites, environmental agents, and therapeutic drugs promote formation of covalent DNA-protein crosslinks (DPCs). Persistent DPCs compromise genome integrity and are eliminated by multiple repair pathways. Aberrant Top1-DNA crosslinks, or Top1ccs, are processed by Tdp1 and Wss1 functioning in parallel pathways in Saccharomyces cerevisiae. It remains obscure how cells choose between diverse mechanisms of DPC repair. Here, we show that several SUMO biogenesis factors (Ulp1, Siz2, Slx5, and Slx8) control repair of Top1cc or an analogous DPC lesion. Genetic analysis reveals that SUMO promotes Top1cc processing in the absence of Tdp1 but has an inhibitory role if cells additionally lack Wss1. In the tdp1Δ wss1Δ mutant, the E3 SUMO ligase Siz2 stimulates sumoylation in the vicinity of the DPC, but not SUMO conjugation to Top1. This Siz2-dependent sumoylation inhibits alternative DPC repair mechanisms, including Ddi1. Our findings suggest that SUMO tunes available repair pathways to facilitate faithful DPC repair.

Ycs4 Subunit of Saccharomyces cerevisiae Condensin Binds DNA and Modulates the Enzyme Turnover.

Condensins play a key role in higher order chromosome organization. In budding yeast Saccharomyces cerevisiae, a condensin complex consists of five subunits: two conserved structural maintenance of chromosome subunits, Smc2 and Smc4, a kleisin Brn1, and two HEAT repeat subunits, Ycg1, which possesses a DNA binding activity, and Ycs4, which can transiently associate with Smc4 and thereby disrupt its association with the Smc2 head. We characterized here DNA binding activity of the non-SMC subunits using an agnostic, model-independent approach. To this end, we mapped the DNA interface of the complex using sulfo-NHS biotin labeling. Besides the known site on Ycg1, we found a patch of lysines at the C-terminal domain of Ycs4 that were protected from biotinylation in the presence of DNA. Point mutations at the predicted protein-DNA interface reduced both Ycs4 binding to DNA and the DNA stimulated ATPase activity of the reconstituted condensin, whereas overproduction of the mutant Ycs4 was detrimental for yeast viability. Notably, the DNA binding site on Ycs4 partially overlapped with its interface with SMC4, revealing an intricate interplay between DNA binding, engagement of the Smc2-Smc4 heads, and ATP hydrolysis and suggesting a mechanism for ATP-modulated loading and translocation of condensins on DNA.

RNF6 enhances radioresistance in colorectal cancer via activating the Wnt pathway.

PURPOSE: RNF6 is verified to promote the malignant growth of colorectal cancer (CRC) and its level is linked to prognosis in CRC patients. Radioresistance is a key factor influencing prognosis in CRC. This study aimed to uncover the potential regulation of ring finger protein 6 (RNF6) in CRC radioresistance. METHODS: RNF6 levels in radioresistant and non-radioresistant CRC patients were detected. In vitro and in vivo regulatory effects of RNF6 on radioresistant CRC cell lines and nude mice bearing radioresistant CRC were examined, respectively. The involvement of Wnt pathway in CRC radioresistance was explored by Western blot. RESULTS: RNF6 was highly expressed in radioresistant CRC species than that of non-radioresistant ones. Identically, RNF6 was upregulated in radioresistant CRC cells compared to parental cells. SW1116 cells overexpressing RNF6 were more tolerant to radiotherapy, and similar results were obtained in nude mice bearing radioresistant CRC with overexpression of RNF6. Moreover, the Wnt pathway was activated during RNF6-induced radioresistance improvement in CRC. CONCLUSIONS: RNF6 enhances radioresistance of CRC through activating the Wnt pathway.

Tumorigenesis and cell competition in Drosophila in the absence of polyhomeotic function.

Cell competition is a homeostatic process that eliminates by apoptosis unfit or undesirable cells from animal tissues, including tumor cells that appear during the life of the organism. In Drosophila there is evidence that many types of oncogenic cells are eliminated by cell competition. One exception is cells mutant for polyhomeotic (ph), a member of the Polycomb family of genes; most of the isolated mutant ph clones survive and develop tumorous overgrowths in imaginal discs. To characterize the tumorigenic effect of the lack of ph, we first studied the growth of different regions of the wing disc deficient in ph activity and found that the effect is restricted to the proximal appendage. Moreover, we found that ph-deficient tissue is partially refractory to apoptosis. Second, we analyzed the behavior of clones lacking ph function and found that many suffer cell competition but are not completely eliminated. Unexpectedly, we found that nonmutant cells also undergo cell competition when surrounded by ph-deficient cells, indicating that within the same tissue cell competition may operate in opposite directions. We suggest two reasons for the incompleteness of cell competition in ph mutant cells: 1) These cells are partially refractory to apoptosis, and 2) the loss of ph function alters the identity of imaginal cells and subsequently their cell affinities. It compromises the winner/loser interaction, a prerequisite for cell competition.

RBMS1 regulates lung cancer ferroptosis through translational control of SLC7A11.

Ferroptosis, an iron-dependent nonapoptotic cell death, is a highly regulated tumor suppressing process. However, functions and mechanisms of RNA-binding proteins in regulation of evasion of ferroptosis during lung cancer progression are still largely unknown. Here, we report that the RNA-binding protein RBMS1 participates in lung cancer development via mediating ferroptosis evasion. Through an shRNA-mediated systematic screen, we discovered that RBMS1 is a key ferroptosis regulator. Clinically, RBMS1 was elevated in lung cancer and its high expression was associated with reduced patient survival. Conversely, depletion of RBMS1 inhibited lung cancer progression both in vivo and in vitro. Mechanistically, RBMS1 interacted with the translation initiation factor eIF3d directly to bridge the 3'- and 5'-UTR of SLC7A11. RBMS1 ablation inhibited the translation of SLC7A11, reduced SLC7A11-mediated cystine uptake, and promoted ferroptosis. In a drug screen that targeted RBMS1, we further uncovered that nortriptyline hydrochloride decreased the level of RBMS1, thereby promoting ferroptosis. Importantly, RBMS1 depletion or inhibition by nortriptyline hydrochloride sensitized radioresistant lung cancer cells to radiotherapy. Our findings established RBMS1 as a translational regulator of ferroptosis and a prognostic factor with therapeutic potential and clinical value.

Molecular Insights into Conformational Heterogeneity and Enhanced Structural Integrity of Helicobacter pylori DNA Binding Protein Hup at Low pH.

The summarized amalgam of internal relaxation modulations and external forces like pH, temperature, and solvent conditions determine the protein structure, stability, and function. In a free-energy landscape, although conformers are arranged in vertical hierarchy, there exist several adjacent parallel sets with conformers occupying equivalent energy cleft. Such conformational states are pre-requisites for the functioning of proteins that have oscillating environmental conditions. As these conformational changes have utterly small re-arrangements, nuclear magnetic resonance (NMR) spectroscopy is unique in elucidating the structure-dynamics-stability-function relationships for such conformations. Helicobacter pylori survives and causes gastric cancer at extremely low pH also. However, least is known as to how the genome of the pathogen is protected from reactive oxygen species (ROS) scavenging in the gut at low pH under acidic stress. In the current study, biophysical characteristics of H. pylori DNA binding protein (Hup) have been elucidated at pH 2 using a combination of circular dichroism, fluorescence, NMR spectroscopy, and molecular dynamics simulations. Interestingly, the protein was found to have conserved structural features, differential backbone dynamics, enhanced stability, and DNA binding ability at low pH as well. In summary, the study suggests the partaking of Hup protein even at low pH in DNA protection for maintaining the genome integrity.

BAF45b Is Required for Efficient Zika Virus Infection of HAP1 Cells.

The 2016 Zika virus (ZIKV) epidemic illustrates the impact of flaviviruses as emerging human pathogens. For unknown reasons, ZIKV replicates more efficiently in neural progenitor cells (NPCs) than in postmitotic neurons. Here, we identified host factors used by ZIKV using the NCI-60 library of cell lines and COMPARE analysis, and cross-analyzed this library with two other libraries of host factors with importance for ZIKV infection. We identified BAF45b, a subunit of the BAF (Brg1/Brm-associated factors) protein complexes that regulate differentiation of NPCs to post-mitotic neurons. ZIKV (and other flaviviruses) infected HAP1 cells deficient in expression of BAF45b and other BAF subunits less efficiently than wildtype (WT) HAP1 cells. We concluded that subunits of the BAF complex are important for infection of ZIKV and other flavivirus. Given their function in cell and tissue differentiation, such regulators may be important determinants of tropism and pathogenesis of arthropod-borne flaviviruses.