A DNA condensation code for linker histones.

Linker histones play an essential role in chromatin packaging by facilitating compaction of the 11-nm fiber of nucleosomal "beads on a string." The result is a heterogeneous condensed state with local properties that range from dynamic, irregular, and liquid-like to stable and regular structures (the 30-nm fiber), which in turn impact chromatin-dependent activities at a fundamental level. The properties of the condensed state depend on the type of linker histone, particularly on the highly disordered C-terminal tail, which is the most variable region of the protein, both between species, and within the various subtypes and cell-type specific variants of a given organism. We have developed an in vitro model system comprising linker histone tail and linker DNA, which although very minimal, displays surprisingly complex behavior, and is sufficient to model the known states of linker histone-condensed chromatin: disordered "fuzzy" complexes ("open" chromatin), dense liquid-like assemblies (dynamic condensates), and higher-order structures (organized 30-nm fibers). A crucial advantage of such a simple model is that it allows the study of the various condensed states by NMR, circular dichroism, and scattering methods. Moreover, it allows capture of the thermodynamics underpinning the transitions between states through calorimetry. We have leveraged this to rationalize the distinct condensing properties of linker histone subtypes and variants across species that are encoded by the amino acid content of their C-terminal tails. Three properties emerge as key to defining the condensed state: charge density, lysine/arginine ratio, and proline-free regions, and we evaluate each separately using a strategic mutagenesis approach.

Identification of COQ2 as a regulator of proliferation and lipid peroxidation through genome-scale CRISPR-Cas9 screening in myeloma cells.

Multiple myeloma (MM) is the second most common malignant haematological disease with a poor prognosis. The limit therapeutic progress has been made in MM patients with cancer relapse, necessitating deeper research into the molecular mechanisms underlying its occurrence and development. A genome-wide CRISPR-Cas9 loss-of-function screening was utilized to identify potential therapeutic targets in our research. We revealed that COQ2 plays a crucial role in regulating MM cell proliferation and lipid peroxidation (LPO). Knockout of COQ2 inhibited cell proliferation, induced cell cycle arrest and reduced tumour growth in vivo. Mechanistically, COQ2 promoted the activation of the MEK/ERK cascade, which in turn stabilized and activated MYC protein. Moreover, we found that COQ2-deficient MM cells increased sensitivity to the LPO activator, RSL3. Using an inhibitor targeting COQ2 by 4-CBA enhanced the sensitivity to RSL3 in primary CD138+ myeloma cells and in a xenograft mouse model. Nevertheless, co-treatment of 4-CBA and RSL3 induced cell death in bortezomib-resistant MM cells. Together, our findings suggest that COQ2 promotes cell proliferation and tumour growth through the activation of the MEK/ERK/MYC axis and targeting COQ2 could enhance the sensitivity to ferroptosis in MM cells, which may be a promising therapeutic strategy for the treatment of MM patients.

Modular Synthesis of Azidobicyclo[2.1.1]hexanes via (3 + 2) Annulation of α-Substituted Vinyl Azides and Bicyclo[1.1.0]butanes.

Here, we present a mild and rapid method to access azidobicyclo[2.1.1]hexanes via formal (3 + 2) cycloaddition of α-substituted vinyl azides and bicyclo[1.1.0]butanes under Lewis acid catalysis. A wide range of α-substituted vinyl azides were tolerated under mild conditions. Notably, the resulting cycloadducts could be transformed into structurally attractive 3-azabicyclo[3.1.1]heptenes through microwave-promoted rearrangement. The utilities were highlighted by copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of tertiary alkyl azide and further transformation of the azide and ketone groups.

Anti-Acute Myeloid Leukemia Activity of CD38-CAR-T Cells with PI3Kδ Downregulation.

We previously constructed a nanobody-based anti-CD38 chimeric antigen receptor T (CD38-CAR-T) cell efficiently against multiple myeloma. As CD38 is also expressed on most tumor cells of acute myeloid leukemia (AML), we wondered about its efficacy in treating AML. In this study, we demonstrated that our CD38-CAR-T cells effectively lysed CD38+ AML cell lines, including NB4, U937, HL-60, THP-1 with an E:T (effector/target cells) ratio of 1:8, and primary AML cells from patients with a low E:T ratio of 1:16. Moreover, recent studies showed that inhibition of PI3Kδ could enhance CAR-T-cell efficacy. We constructed PI3Kδ-downregulated CD38-CAR-T cells with a CD38-CAR lentiviral vector containing short hairpin RNA (shRNA) sequences against PI3Kδ. CD38-CAR-T cells with PI3Kδ downregulation maintained their antileukemia function against both AML cell lines and primary AML cells while reducing the release of IL-2, IFN-γ, and TNF when co-culturing with AML cell lines. Both CD38-CAR-T and PI3Kδ-downregulated CD38-CAR-T-cell therapy significantly improved the survival of AML mice, whereas the latter had an even better effect on survival. In summary, our study demonstrated that CD38-CAR-T cells had promising activity against AML, and PI3Kδ downregulation in CD38-CAR-T cells could reduce some cytokines release without impairing their antileukemia function.

Alternative splicing analysis showed the splicing factor polypyrimidine tract-binding protein 1 as a potential target in acute myeloid leukemia therapy.

Alternative splicing (AS) is a universal post-transcriptional regulation process in cells, and increasing evidences have validated its crucial role in tumors. We collected AS event, gene expression, and clinical data of 178 AML patients from The Cancer Genome Atlas (TCGA) project. More than 1,000 AS events were found associated with overall survival (OS), and alternate promoter (AP) events were the most significant. The expression of the KIAA0930 transcript was the most significantly different AS event selected from AP events and significantly correlated with the expression of the splicing factor (SF) polypyrimidine tract-binding protein 1 (PTBP1). Then, the roles of PTBP1 on AS of the KIAA0930 and the proliferation of AML cells were confirmed. KIAA0930 variant 1 (KIAA0930-1) was upregulated and variant 2 (KIAA0930-2) downregulated with knockdown PTBP1 expression of AML cells by specific shRNA. A low level of PTBP1 can decrease the proliferation ability of AML cells. In conclusion, the results showed that PTBP1 might be a potential target for AML therapy.

RNF220 promotes the proliferation of leukaemic cells and reduces the degradation of the Cyclin D1 protein through USP22.

Ring finger proteins contain a characteristic ring finger motif and perform a wide range of biological functions in living organisms. These genes are abnormally expressed in many cancers. We found that the expression level of Ring finger protein 220 (RNF220) was negatively correlated with the disease-free survival (DFS) and overall survival (OS) of acute myeloid leukaemia (AML) patients. Moreover, the mRNA level of this gene is significantly higher in the bone marrow cells of AML patients than in the mobilized peripheral blood haematopoietic stem cells of healthy donors. The overexpression of RNF220 promotes the proliferation of AML cells and accelerates the transition from G1 phase to S phase. Increased protein levels and decreased ubiquitylation levels of Cyclin D1 were observed in the nuclei of cells overexpressing RNF220 compared to those of control cells. The protein level of USP22 was also increased in cells overexpressing RNF220. RNF220 cannot enhance the stability of the Cyclin D1 protein without increased expression of the USP22 protein. Our study provided proof of principle to show that RNF220 promotes stabilization of the Cyclin D1 protein via USP22.

CircBA9.3 supports the survival of leukaemic cells by up-regulating c-ABL1 or BCR-ABL1 protein levels.

The unchecked tyrosine kinase activity of BCR-ABL1 contributes to the immortality of leukaemic cells. Therefore, this oncogene is a highly important therapeutic target for chronic myelogenous leukaemia (CML). Tyrosine kinase inhibitors (TKIs) are an excellent drug treatment for CML patients. However, there are still some patients who are not responsive to TKIs. We found that a novel circular RNA (circRNA), named circBA9.3, is derived from BCR-ABL1. CircBA9.3 can efficiently promote the proliferation and inhibit apoptosis of cancer cells. In addition, some patients with TKI resistance have elevated circBA9.3 expression, which is positively correlated with the level of BCR-ABL1. Furthermore, circBA9.3 is predominantly located in the cytoplasm and enhances c-ABL1 and BCR-ABL1 oncoprotein expression. Thus, circBA9.3 is a molecule associated with increased tyrosine kinase activity that promotes resistance against TKI therapy. In this study, we provided a new potential target for the treatment of TKI-resistant CML patients.

Facile access to bicyclo[2.1.1]hexanes by Lewis acid-catalyzed formal cycloaddition between silyl enol ethers and bicyclo[1.1.0]butanes.

Saturated three-dimensional carbocycles have gained increasing prominence in synthetic and medicinal chemistry. In particular, bicyclo[2.1.1]hexanes (BCHs) have been identified as the molecular replacement for benzenes. Here, we present facile access to a variety of BCHs via a stepwise two-electron formal (3 + 2) cycloaddition between silyl enol ethers and bicyclo[1.1.0]butanes (BCBs) under Lewis acid catalysis. The reaction features wide functional group tolerance for silyl enol ethers, allowing the efficient construction of two vicinal quaternary carbon centers and a silyl-protected tertiary alcohol unit in a streamlined fashion. Interestingly, the reaction with conjugated silyl dienol ethers can provide access to bicyclo[4.1.1]octanes (BCOs) equipped with silyl enol ethers that facilitate further transformation. The utilities of this methodology are demonstrated by the late-stage modification of natural products, transformations of tertiary alcohol units on bicyclo[2.1.1]hexane frameworks, and derivatization of silyl enol ethers on bicyclo[4.1.1]octanes, delivering functionalized bicycles that are traditionally inaccessible.

Robust All-Day Frostphobic Surfaces.

The application of solar-thermal surfaces for antifrosting and defrosting has emerged as a passive and environmentally friendly approach to mitigate the negative consequences of frost formation, such as structural damage and reduced heat transfer efficiency. However, achieving robust all-day frostphobicity solely through interfacial modification and solar-thermal effects is challenging in practical applications: The thick frost that accumulates at night strongly scatters solar radiation, rendering the solar-thermal coatings ineffective during the daytime. Additionally, these nanostructured coatings are susceptible to wear and tear when exposed to the outdoors for extended periods of time. To address these challenges, we present an innovative frostphobic surface that incorporates V-grooved structures with superhydrophobic solar-thermal layers (VSSs). The out-of-plane gradient structures facilitate spatially regulated vapor diffusion, an enhanced photothermal effect, and robust water repellency. These features not only prevent frost from covering the entire surface overnight, enabling effective solar-thermal defrosting during the daytime, but also protect the surface from deterioration. The combined merits ensure robust all-day frostphobicity and exceptional durability, making the VSS surface promising for practical applications and extending the lifespan in extreme environments.

Downregulation of RCN1 promotes pyroptosis in acute myeloid leukemia cells.

Reticulocalbin-1 (RCN1) is expressed aberrantly and at a high level in various tumors, including acute myeloid leukemia (AML), yet its impact on AML remains unclear. In this study, we demonstrate that RCN1 knockdown significantly suppresses the viability of bone marrow mononuclear cells (BMMNCs) from AML patients but does not affect the viability of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSCs) from healthy donors in vitro. Downregulation of RCN1 also reduces the viability of AML cell lines. Further studies showed that the RCN1 knockdown upregulates type I interferon (IFN-1) expression and promotes AML cell pyroptosis through caspase-1 and gasdermin D (GSDMD) signaling. Deletion of the mouse Rcn1 gene inhibits the viability of mouse AML cell lines but not the hematopoiesis of mouse bone marrow. In addition, RCN1 downregulation in human AML cells significantly inhibited tumor growth in the NSG mouse xenograft model. Taken together, our results suggest that RCN1 may be a potential target for AML therapy.