Development of Potent MALT1 Inhibitors Featuring a Novel "2-Thioxo-2,3-dihydrothiazolo[4,5-d]pyrimidin-7(6H)-one" Scaffold for the Treatment of B Cell Lymphoma.

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) has emerged as a novel and promising therapeutic target for the treatment of lymphomas and autoimmune diseases. Herein, we reported a new class of MALT1 inhibitors featuring a novel "2-thioxo-2,3-dihydrothiazolo[4,5-d]pyrimidin-7(6H)-one" scaffold developed by structure-based drug design. Structure-activity relationship studies finally led to the discovery of MALT1 inhibitor 10m, which covalently and potently inhibited MALT1 protease with the IC50 value of 1.7 µM. 10m demonstrated potent and selective antiproliferative activity against ABC-DLBCL and powerful ability to induce HBL1 apoptosis. 10m also effectively downregulated the activities of MALT1 and its downstream signal pathways. Furthermore, 10m induced upregulation of mTOR and PI3K-Akt signals and exhibited a synergistic antitumor effect with Rapamycin in HBL1 cells. More importantly, 10m remarkably suppressed the tumor growth both in the implanted HBL1 and TMD8 xenograft models. Collectively, this work provides valuable MALT1 inhibitors with a distinct core structure.

Glyburide Regulates UCP1 Expression in Adipocytes Independent of KATP Channel Blockade.

Identification of safe and effective compounds to increase or activate UCP1 expression in brown or white adipocytes remains a potent therapeutic strategy to combat obesity. Here we reported that, glyburide, one of the FDA-approved drugs currently used to treat type 2 diabetes, can significantly enhance UCP1 expression in both brown and white adipocytes. Glyburide-fed mice exhibited a clear resistance to high-fat diet-induced obesity, reduced blood triglyceride level, and increased UCP1 expression in brown adipose tissue. Moreover, in situ injection of glyburide to inguinal white adipose tissue remarkably enhanced UCP1 expression and increased thermogenesis. Further mechanistic studies indicated that the glyburide effect in UCP1 expression in adipocytes was KATP channel independent but may involve the regulation of the Ca2+-Calcineurin-NFAT signal pathway. Overall, our findings revealed the significant effects of glyburide in regulating UCP1 expression and thermogenesis in adipocytes, which can be potentially repurposed to treat obesity.

MRG15 orchestrates rhythmic epigenomic remodelling and controls hepatic lipid metabolism.

The rhythmic regulation of transcriptional processes is intimately linked to lipid homeostasis, to anticipate daily changes in energy access. The Rev-erbα-HDAC3 complex was previously discovered to execute the rhythmic repression of lipid genes; however, the epigenetic switch that turns on these genes is less clear. Here, we show that genomic recruitment of MRG15, which is encoded by the mortality factor on chromosome 4 (MORF4)-related gene on chromosome 15, displays a significant diurnal rhythm and activates lipid genes in the mouse liver. RNA polymerase II (Pol II) recruitment and histone acetylation correspond to MRG15 binding, and the rhythm is impaired upon MRG15 depletion, establishing MRG15 as a key modulator in global rhythmic transcriptional regulation. MRG15 interacts with the nuclear receptor LRH-1, rather than with known core clock proteins, and is recruited to genomic loci near lipid genes via LRH-1. Blocking of MRG15 by CRISPR targeting or by the FDA-approved drug argatroban, which is an antagonist to MRG15, attenuates liver steatosis. This work highlights MRG15 as a targetable master regulator in the rhythmic regulation of hepatic lipid metabolism.

Type 2 Diabetes Variants in the SLC16A11 Coding Region Are Not Loss-of-Function Mutations.

This Matters Arising Response paper addresses the Hoch et al. (2019) Matters Arising paper published concurrently in this issue of Cell Reports. The genetic study in humans revealed a strong association of DNA variants in the SLC16A11 coding region with type 2 diabetes mellitus (T2DM). However, how these T2D variants affect the function of SLC16A11 remains controversial. In Zhao et al. (2019), with studies using genetic knockout mouse models and in vivo gene reconstitution experiments, we demonstrated gain of aberrant functions of mutant SLC16A11-carrying T2D variants, which cause liver steatosis and insulin resistance. Hoch et al. (2019) raise concerns regarding the animal models and experimental settings used in the study. Here, we address their concerns and emphasize that discoveries from the physiological studies of SLC16A11 by using mouse models disagree with the previous proposal by Rusu et al. (2017) that "therapeutics that enhance SLC16A11 levels or activity may be beneficial for T2D."

Identification of a rhodanine derivative BML-260 as a potent stimulator of UCP1 expression.

Identification of proper agents to increase or activate UCP1+ cells in adipose tissues remains a potent therapeutic strategy to combat obesity. Screening systems for UCP1 activators have been previously established and allow for unbiased discovery of effective compound(s). Methods: A previously established Ucp1-2A-GFP reporter system was applied to a chemical library containing 33 phosphatase inhibitors. Compounds that can significantly activate UCP1 expression were further tested in vivo in mouse adipose tissues. Possible underlying mechanism was explored via RNA profiling, CMAP analysis, CRISPR targeting as well as inhibitor treatments. Results: We identified BML-260, a known potent inhibitor of the dual-specific phosphatase JSP-1, that significantly increased UCP1 expression in both brown and white adipocytes. BML-260 treatment also activated oxidative phosphorylation genes, increased mitochondrial activity as well as heat generation in vitro and in vivo. Mechanistic studies revealed that effect of BML-260 on adipocytes was partly through activated CREB, STAT3 and PPAR signaling pathways, and was unexpectedly JSP-1 independent. Conclusion: The rhodanine derivate BML-260 was previously identified to be a JSP-1 inhibitor, and thus was proposed to treat inflammatory and proliferative disorders associated with dysfunctional JNK signaling. This work provides evidences that BML-260 can also exert a JSP-1-independent effect in activating UCP1 and thermogenesis in adipocytes, and be potentially applied to treat obesity.

Gain-of-Function Mutations of SLC16A11 Contribute to the Pathogenesis of Type 2 Diabetes.

DNA variants in the SLC16A11 coding region were identified to be strongly associated with type 2 diabetes (T2DM) in a Mexican population. Previous studies suggested that these variants disrupt SLC16A11 function and therefore proposed to revive SLC16A11 levels or activity to achieve therapeutic benefit. However, with knockout mouse models, here we show that Slc16a11 depletion has no significant metabolic defects. Further studies demonstrate that reconstitution of the mutant, but not the wild-type Slc16a11, in the liver of knockout mice causes more triglyceride accumulation and induction of insulin resistance via upregulation of lipin 1, suggesting gaining of aberrant functions of the mutant protein that affects lipid metabolism. Our findings offer a different explanation to the function of these diabetic variants, challenging the concept of enhancing SLC16A11 function to treat T2DM. The contradictory results by our and previous studies suggest that how the SLC16A11 locus contributes to human metabolism warrants further investigation.

Screening of FDA-approved drugs identifies sutent as a modulator of UCP1 expression in brown adipose tissue.

BACKGROUND: The pharmacological activation of thermogenesis in brown adipose tissue has long been considered promising strategies to treat obesity. However, identification of safe and effective agents remains a challenge. In this study, we addressed this challenge by developing a cellular system with a fluorescence readout, and applied in a high-throughput manner to screen for FDA-approved drugs that may activate endogenous UCP1 expression in adipocytes. METHODS: We have generated a Ucp1-2A-GFP reporter mouse, in which GFP intensity serves as a surrogate of the endogenous expression level of UCP1 protein; and immortalized brown adipocytes were derived from this mouse model and applied in drug screening. Candidate drugs were further tested in mouse models either fed with normal chow or high fat diet to induce obesity. FINDINGS: By using the cellular screening platform, we identified a group of FDA-approved drugs that can upregulate UCP1 expression in brown adipocyte, including previously known UCP1 activators and new candidate drugs. Further studies focusing on a previously unreported drug-sutent, revealed that sutent treatment could increase the energy expenditure and inhibit lipid synthesis in mouse adipose and liver tissues, resulting in improved metabolism and resistance to obesity. INTERPRETATION: This study offered an easy-to-use cellular screening system for UCP1 activators, and provided a candidate list of FDA-approved drugs that can potentially treat obesity. Further study of these candidates may shed new light on the drug discovery towards obesity. FUND: National Key Research and Development Program and the Strategic Priority Research Program of the Chinese Academy of Sciences, etc. (250 words).

Genetic and Chemical Screenings Identify HDAC3 as a Key Regulator in Hepatic Differentiation of Human Pluripotent Stem Cells.

Hepatocyte-like cells (HLCs) derived from human pluripotent stem cells (hPSCs) offer a promising cell resource for disease modeling and transplantation. However, differentiated HLCs exhibit an immature phenotype and comprise a heterogeneous population. Thus, a better understanding of HLC differentiation will improve the likelihood of future application. Here, by taking advantage of CRISPR-Cas9-based genome-wide screening technology and a high-throughput hPSC screening platform with a reporter readout, we identified several potential genetic regulators of HLC differentiation. By using a chemical screening approach within our platform, we also identified compounds that can further promote HLC differentiation and preserve the characteristics of in vitro cultured primary hepatocytes. Remarkably, both screenings identified histone deacetylase 3 (HDAC3) as a key regulator in hepatic differentiation. Mechanistically, HDAC3 formed a complex with liver transcriptional factors, e.g., HNF4, and co-regulated the transcriptional program during hepatic differentiation. This study highlights a broadly useful approach for studying and optimizing hPSC differentiation.