UNASSIGNED: Endothelial dysfunction is an early and pre-clinical manifestation of coronary heart disease (CHD).
UNASSIGNED: This study investigates the role of DDX5 in oxidized low-density lipoprotein (ox-LDL)-induced endothelial cell injury to confer novel targets for the treatment of CHD.
UNASSIGNED: Endothelial cells were induced by ox-LDL. DDX5, pri-miR-640, pre-miR-640, miR-640, and SOX6 expressions were analyzed by RT-qPCR and Western blot. DDX5 expression was intervened by shRNA, followed by CCK-8 analysis of proliferation, flow cytometry detection of apoptosis, and tube formation assay analysis of angiogenic potential of cells. The binding between DDX5 and pri-miR-640 was determined by RIP, and the pri-miR-640 RNA stability was measured after actinomycin D treatment. Dual-luciferase assay verified the targeting relationship between miR-640 and SOX6.
UNASSIGNED: DDX5 and miR-640 were highly expressed while SOX6 was poorly expressed in ox-LDL-induced endothelial cells. Silence of DDX5 augmented cell proliferation, abated apoptosis, and facilitated angiogenesis. Mechanistically, RNA binding protein DDX5 elevated miR-640 expression by weakening the degradation of pri-miR-640, thereby reducing SOX6 expression. Combined experimental results indicated that overexpression of miR-640 or low expression of SOX6 offset the protective effect of DDX5 silencing on cell injury.
UNASSIGNED: DDX5 elevates miR-640 expression by repressing the degradation of pri-miR-640 and then reduces SOX6 expression, thus exacerbating ox-LDL-induced endothelial cell injury.

As an RNA binding protein (RBP), DDX5 is widely involved in the regulation of various biological activities. While recent studies have confirmed that DDX5 can act as a transcriptional cofactor that is involved in the formation of gametes, few studies have investigated whether DDX5 can be used as a transcription factor to regulate the formation of primordial germ cells (PGCs). In this study, we found that DDX5 was significantly up-regulated during chicken PGC formation. Under different PGC induction models, the overexpression of DDX5 not only up-regulates PGC markers but also significantly improves the formation efficiency of primordial germ cell-like cells (PGCLC). Conversely, the inhibition of DDX5 expression can significantly inhibit both the expression of PGC markers and PGCLC formation efficiency. The effect of DDX5 on PGC formation in vivo was consistent with that seen in vitro. Interestingly, DDX5 not only participates in the formation of PGCs but also positively regulates their migration and proliferation. In the process of studying the mechanism by which DDX5 regulates PGC formation, we found that DDX5 acts as a transcription factor to bind to the promoter region of BMP4-a key gene for PGC formation-and activates the expression of BMP4. In summary, we confirm that DDX5 can act as a positive transcription factor to regulate the formation of PGCs in chickens. The obtained results not only enhance our understanding of the way in which DDX5 regulates the development of germ cells but also provide a new target for systematically optimizing the culture and induction system of PGCs in chickens in vitro.

UNASSIGNED: Heart failure (HF) is a leading cause of morbidity and mortality worldwide. RNA-binding proteins are identified as regulators of cardiac disease; DDX5 (dead-box helicase 5) is a master regulator of many RNA processes, although its function in heart physiology remains unclear.
UNASSIGNED: We assessed DDX5 expression in human failing hearts and a mouse HF model. To study the function of DDX5 in heart, we engineered cardiomyocyte-specific Ddx5 knockout mice. We overexpressed DDX5 in cardiomyocytes using adeno-associated virus serotype 9 and performed transverse aortic constriction to establish the murine HF model. The mechanisms underlined were subsequently investigated using immunoprecipitation-mass spectrometry, RNA-sequencing, alternative splicing analysis, and RNA immunoprecipitation sequencing.
UNASSIGNED: We screened transcriptome databases of murine HF and human dilated cardiomyopathy samples and found that DDX5 was significantly downregulated in both. Cardiomyocyte-specific deletion of Ddx5 resulted in HF with reduced cardiac function, an enlarged heart chamber, and increased fibrosis in mice. DDX5 overexpression improved cardiac function and protected against adverse cardiac remodeling in mice with transverse aortic constriction-induced HF. Furthermore, proteomics revealed that DDX5 is involved in RNA splicing in cardiomyocytes. We found that DDX5 regulated the aberrant splicing of Ca2+/calmodulin-dependent protein kinase IIδ (CamkIIδ), thus preventing the production of CaMKIIδA, which phosphorylates L-type calcium channel by serine residues of Cacna1c, leading to impaired Ca2+ homeostasis. In line with this, we found increased intracellular Ca2+ transients and increased sarcoplasmic reticulum Ca2+ content in DDX5-depleted cardiomyocytes. Using adeno-associated virus serotype 9 knockdown of CaMKIIδA partially rescued the cardiac dysfunction and HF in Ddx5 knockout mice.
UNASSIGNED: These findings reveal a role for DDX5 in maintaining calcium homeostasis and cardiac function by regulating alternative splicing in cardiomyocytes, identifying the DDX5 as a potential target for therapeutic intervention in HF.

A significant variation in chromatin accessibility is an epigenetic feature of leukemia. The cause of this variation in leukemia, however, remains elusive. Here, we identify SMARCA5, a core ATPase of the imitation switch (ISWI) chromatin remodeling complex, as being responsible for aberrant chromatin accessibility in leukemia cells. We find that SMARCA5 is required to maintain aberrant chromatin accessibility for leukemogenesis and then promotes transcriptional activation of AKR1B1, an aldo/keto reductase, by recruiting transcription co-activator DDX5 and transcription factor SP1. Higher levels of AKR1B1 are associated with a poor prognosis in leukemia patients and promote leukemogenesis by reprogramming fructose metabolism. Moreover, pharmacological inhibition of AKR1B1 has been shown to have significant therapeutic effects in leukemia mice and leukemia patient cells. Thus, our findings link the aberrant chromatin state mediated by SMARCA5 to AKR1B1-mediated endogenous fructose metabolism reprogramming and shed light on the essential role of AKR1B1 in leukemogenesis, which may provide therapeutic strategies for leukemia.

OBJECTIVE: The type X collagen gene (Col10a1), is a specific molecular marker of hypertrophic chondrocytes during endochondral ossification. Col10a1 expression is known to be influenced by many regulators. In this study, we aim to investigate how DEAD-box helicase 5 (DDX5), a potential binding factor for Col10a1 enhancer, may play a role in Col10a1 expression and chondrocyte hypertrophic differentiation in vitro.
METHODS: The potential binding factors of the 150-bp Col10a1 cis-enhancer were identified with the hTFtarget database. The expression of DDX5 and COL10A1 was detected by quantitative real-time PCR (qRT-PCR) and Western blot in chondrogenic ATDC5 and MCT cell models with or without Ddx5 knockdown or overexpression. Dual-luciferase reporter assay and chromatin immunoprecipitation (ChIP) were performed to determine the interaction between DDX5 and the Col10a1 enhancer. The effect and mechanism of DDX5 on chondrocyte differentiation and maturation was evaluated by alcian blue, alkaline phosphatase (ALP), and alizarin red staining in ATDC5 cell lines with stable knockdown of Ddx5.
RESULTS: DDX5 was identified as a potential binding factor for the Col10a1 enhancer. The expression of DDX5 in hypertrophic chondrocytes was higher than that in proliferative chondrocytes. Knockdown of Ddx5 decreased, while overexpression of Ddx5 slightly increased COL10A1 expression. DDX5 promotes the enhancer activity of Col10a1 as demonstrated by dual-luciferase reporter assay, and the ChIP experiment suggests a direct interaction between DDX5 and the Col10a1 enhancer. Compared to the control (NC) group, we observed weaker alcian blue and ALP staining intensity in the Ddx5 knockdown group of ATDC5 cells cultured both for 7 and 14 days. Whereas weaker alizarin red staining intensity was only found in the Ddx5 knockdown group of cells cultured for 7 days. Meanwhile, knockdown of Ddx5 significantly reduced the level of runt-related transcription factor 2 (RUNX2) in related ATDC5 cells examined.
CONCLUSIONS: Our results suggest that DDX5 acts as a positive regulator for Col10a1 expression and may cooperate with RUNX2 together to control Col10a1 expression and promote the proliferation and maturation of chondrocytes.

The authors have requested that this preprint be removed from Research Square.

Chronic myeloid leukemia (CML) is induced by the expression of the fused tyrosine kinase BCR-ABL, which is caused by a chromosomal translocation. BCR-ABL inhibitors have been used to treat CML; however, the acquisition of resistance by CML cells during treatment is a serious issue. We herein demonstrated that BCR-ABL induced the expression of the RNA helicase DDX5 in K562 cells derived from CML patients in a manner that was dependent on its kinase activity, which resulted in cell proliferation and survival. The knockout of DDX5 decreased the expression of BIRC5 (survivin) and activated caspase 3, leading to apoptosis in K562 cells. Similar results were obtained in cells treated with FL118, an inhibitor of DDX5 and a derivative compound of camptothecin (CPT). Furthermore, FL118 potently induced apoptosis not only in Ba/F3 cells expressing BCR-ABL, but also in those expressing the BCR-ABL T315I mutant, which is resistant to BCR-ABL inhibitors. Collectively, these results revealed that DDX5 is a critical therapeutic target in CML and that FL118 is an effective candidate compound for the treatment of BCR-ABL inhibitor-resistant CML.

RNA helicases are emerging as key factors regulating host-virus interactions. The DEAD-box ATP-dependent RNA helicase DDX5, which plays an important role in many aspects of cellular RNA biology, was also found to either promote or inhibit viral replication upon infection with several RNA viruses. Here, our aim is to examine the impact of DDX5 on Sindbis virus (SINV) infection.
We analysed the interaction between DDX5 and the viral RNA using imaging and RNA-immunoprecipitation approaches. The interactome of DDX5 in mock- and SINV-infected cells was determined by mass spectrometry. We validated the interaction between DDX17 and the viral capsid by co- immunoprecipitation in the presence or absence of an RNase treatment. We determined the subcellular localization of DDX5, its cofactor DDX17 and the viral capsid protein by co-immunofluorescence. Finally, we investigated the impact of DDX5 depletion and overexpression on SINV infection at the viral protein, RNA and infectious particle accumulation level. The contribution of DDX17 was also tested by knockdown experiments.
In this study we demonstrate that DDX5 interacts with the SINV RNA during infection. Furthermore, the proteomic analysis of the DDX5 interactome in mock and SINV-infected HCT116 cells identified new cellular and viral partners and confirmed the interaction between DDX5 and DDX17. Both DDX5 and DDX17 re-localize from the nucleus to the cytoplasm upon SINV infection and interact with the viral capsid protein. We also show that DDX5 depletion negatively impacts the viral replication cycle, while its overexpression has a pro-viral effect. Finally, we observed that DDX17 depletion reduces SINV infection, an effect which is even more pronounced in a DDX5-depleted background, suggesting a synergistic pro-viral effect of the DDX5 and DDX17 proteins on SINV.
These results not only shed light on DDX5 as a novel and important host factor to the SINV life cycle, but also expand our understanding of the roles played by DDX5 and DDX17 as regulators of viral infections.

SARS-CoV-2, the causative agent of COVID-19, has been intensely studied in search of effective antiviral treatments. The immunosuppressant cyclosporine A (CsA) has been suggested to be a pan-coronavirus inhibitor, yet its underlying mechanism remained largely unknown. Here, we found that non-structural protein 1 (Nsp1) of SARS-CoV-2 usurped CsA-suppressed nuclear factor of activated T cells (NFAT) signaling to drive the expression of cellular DEAD-box helicase 5 (DDX5), which facilitates viral replication. Nsp1 interacted with calcineurin A (CnA) to displace the regulatory protein regulator of calcineurin 3 (RCAN3) of CnA for NFAT activation. The influence of NFAT activation on SARS-CoV-2 replication was also validated by using the Nsp1-deficient mutant virus. Calcineurin inhibitors, such as CsA and VIVIT, inhibited SARS-CoV-2 replication and exhibited synergistic antiviral effects when used in combination with nirmatrelvir. Our study delineated the molecular mechanism of CsA-mediated inhibition of SARS-CoV-2 replication and the anti-SARS-CoV-2 action of calcineurin inhibitors.
OBJECTIVE: Cyclosporine A (CsA), commonly used to inhibit immune responses, is also known to have anti-SARS-CoV-2 activity, but its mode of action remains elusive. Here, we provide a model to explain how CsA antagonizes SARS-CoV-2 through three critical proteins: DDX5, NFAT1, and Nsp1. DDX5 is a cellular facilitator of SARS-CoV-2 replication, and NFAT1 controls the production of DDX5. Nsp1 is a viral protein absent from the mature viral particle and capable of activating the function of NFAT1 and DDX5. CsA and similar agents suppress Nsp1, NFAT1, and DDX5 to exert their anti-SARS-CoV-2 activity either alone or in combination with Paxlovid.

Our study was to elucidate the role of RNA helicase DEAD-Box Helicase 17 (DDX17) in NAFLD and to explore its underlying mechanisms.
We created hepatocyte-specific Ddx17-deficient mice aim to investigate the impact of Ddx17 on NAFLD induced by a high-fat diet (HFD) as well as methionine and choline-deficient l-amino acid diet (MCD) in adult male mice. RNA-seq and lipidomic analyses were conducted to depict the metabolic landscape, and CUT&Tag combined with chromatin immunoprecipitation (ChIP) and luciferase reporter assays were conducted.
In this work, we observed a notable increase in DDX17 expression in the livers of patients with NASH and in murine models of NASH induced by HFD or MCD. After introducing lentiviruses into hepatocyte L02 for DDX17 knockdown or overexpression, we found that lipid accumulation induced by palmitic acid/oleic acid (PAOA) in L02 cells was noticeably weakened by DDX17 knockdown but augmented by DDX17 overexpression. Furthermore, hepatocyte-specific DDX17 knockout significantly alleviated hepatic steatosis, inflammatory response and fibrosis in mice after the administration of MCD and HFD. Mechanistically, our analysis of RNA-seq and CUT&Tag results combined with ChIP and luciferase reporter assays indicated that DDX17 transcriptionally represses Cyp2c29 gene expression by cooperating with CCCTC binding factor (CTCF) and DEAD-Box Helicase 5 (DDX5). Using absolute quantitative lipidomics analysis, we identified a hepatocyte-specific DDX17 deficiency that decreased lipid accumulation and altered lipid composition in the livers of mice after MCD administration. Based on the RNA-seq analysis, our findings suggest that DDX17 could potentially have an impact on the modulation of lipid metabolism and the activation of M1 macrophages in murine NASH models.
These results imply that DDX17 is involved in NASH development by promoting lipid accumulation in hepatocytes, inducing the activation of M1 macrophages, subsequent inflammatory responses and fibrosis through the transcriptional repression of Cyp2c29 in mice. Therefore, DDX17 holds promise as a potential drug target for the treatment of NASH.