Project description:b-cell proliferation induction is one of the most tangible therapeutic strategies to restore b-cell mass. However, this approach has proven challenging due to a remarkable resistance of adult human b-cells to proliferation. Here we aim to unravel the role of a non-canonical IkB kinase TBK1 (TANK-binding kinase 1), which is predominantly expressed in b-cells in mammalian islets, in regulating cell cycle progression. Genetic silencing of TBK1 in INS-1 832/13 rat b-cell line promoted proliferation of b-cells. Proteomic and transcriptome analyses further revealed changes of proteins and genes critical for cell growth and proliferation, including upregulation of ribosomal proteins and cell cycle regulators, upon depletion of TBK1. TBK1 overexpression decreased sensitivity of b-cells to the elevation of cAMP levels and reduced proliferation of b-cells in a manner dependent on the activity of phosphodiesterase 3 (PDE3). Importantly, pharmacological inhibition of TBK1 using (E)3-(3-phenylbenzo[c]isoxazol-5-yl) acrylic acid (PIAA) augmented proliferation and function of rat and human embryonic stem cell (hESC)-derived insulin-producing b-cells under basal conditions. Diabetogenic insults further induced TBK1 expression and accordingly, PIAA protected b-cells against cytokine- and streptozotocin-induced diabetogenic challenges and promoted b-cell replication. Furthermore, PIAA increased proliferation of β-cells in normal and type 2 diabetic human islets with elevation in insulin secretion. Altogether, these data unveil novel and essential function of TBK1 as a key cell-autonomous negative regulator of b-cell replication and presenting PIAA as a valid therapeutic strategy for augmenting proliferation and function of b-cells.
Project description:Small-molecule inhibitors of non-canonical IκB kinases TANK-binding kinase 1 (TBK1) and IκB kinase ε (IKKε) have shown to stimulate β-cell regeneration in multiple species. Here we demonstrate that TBK1 is predominantly expressed in β-cells in mammalian islets. Proteomic and transcriptome analyses revealed that genetic silencing of TBK1 increased expression of proteins and genes essential for cell proliferation in INS-1 832/13 rat β-cells. Conversely, TBK1 overexpression decreased sensitivity of β-cells to the elevation of cyclic AMP (cAMP) levels and reduced proliferation of β-cells in a manner dependent on the activity of cAMP-hydrolyzing phosphodiesterase 3 (PDE3). While the mitogenic effect of (E)3-(3-phenylbenzo[c]isoxazol-5-yl)acrylic acid (PIAA) is derived from inhibition of TBK1, PIAA augmented glucose-stimulated insulin secretion (GSIS) and expression of β-cell differentiation and proliferation markers in human embryonic stem cell (hESC)-derived β-cells and human islets. TBK1 expression was increased in β-cells upon diabetogenic insults, including in human type 2 diabetic islets. PIAA enhanced expression of cell cycle control molecules and β-cell differentiation markers upon diabetogenic challenges, and accelerated restoration of functional β-cells in streptozotocin (STZ)-induced diabetic mice. Altogether, these data suggest the critical function of TBK1 as a β-cell autonomous replication barrier and present PIAA as a valid therapeutic strategy augmenting functional β-cells.
Project description:?-cell proliferation induction is a promising therapeutic strategy to restore ?-cell mass. By screening small molecules in a transgenic zebrafish model of type 1 diabetes, we identified inhibitors of non-canonical I?B kinases (IKKs), TANK-binding kinase 1 (TBK1) and I?B kinase ? (IKK?), as enhancers of ?-cell regeneration. The most potent ?-cell regeneration enhancer was a cinnamic acid derivative (E)-3-(3-phenylbenzo[c]isoxazol-5-yl)acrylic acid (PIAA), which, acting through the cAMP-dependent protein kinase A (PKA), stimulated ?-cell-specific proliferation by increasing cyclic AMP (cAMP) levels and mechanistic target of rapamycin (mTOR) activity. A combination of PIAA and cilostamide, an inhibitor of ?-cell-enriched cAMP hydrolyzing enzyme phosphodiesterase (PDE) 3, enhanced ?-cell proliferation, whereas overexpression of PDE3 blunted the mitogenic effect of PIAA in zebrafish. PIAA augmented proliferation of INS-1?-cells and ?-cells in mammalian islets including human islets with elevation in cAMP levels and insulin secretion. PIAA improved glycemic control in streptozotocin (STZ)-induced diabetic mice with increases in ?-cell proliferation, ?-cell area, and insulin content in the pancreas. Collectively, these data reveal an evolutionarily conserved and critical role of TBK1/IKK? suppression in expanding functional ?-cell mass.
Project description:Germinal center (GC) is a site where somatic hypermutation and clonal selection are coupled for antibody affinity maturation against infections. However, how GCs are formed and regulated is incompletely understood. Here, we identified an unexpected role of Tank-binding kinase-1 (TBK1) as a crucial B-cell-intrinsic factor for GC formation. Using immunization and malaria infection models, we show that TBK1-deficient B cells failed to form GC despite normal Tfh differentiation, although some malaria-infected B-cell-specific TBK1-deficient mice could survive by GC-independent mechanisms. Mechanistically, TBK1 phosphorylation elevates in B cells during GC differentiation and regulates the balance of IRF4/BCL6 expression by limiting CD40 and BCR activation through non-canonical NF-κB and AKTT308 signaling. In the absence of TBK1, CD40 and BCR signaling synergistically enhanced IRF4 expression in Pre-GC leading to BCL6 suppression, therefore failed to form GC. As a result, memory B cells generated from TBK1-deficient B cells fail to confer sterile immunity upon re-infection, suggesting that TBK1 determines B cell fate to promote long-lasting humoral immunity.
Project description:The purpose of the dataset is to analyze expression of genes induced by KRAS and regulated by TBK1; The proto-oncogene KRAS is mutated in a wide array of human cancers, most of which are aggressive and respond poorly to standard therapies. Although the identification of specific oncogenes has led to the development of clinically effective, molecularly targeted therapies in some cases, KRAS has remained refractory to this approach. An alternative strategy for targeting KRAS is to identify gene products that, when suppressed or inhibited, result in cell death only in the presence of an oncogenic allele. Here we have used systematic RNA interference (RNAi) to detect synthetic lethal partners of oncogenic KRAS and found that the non-canonical IkB kinase, TBK1, was selectively essential in cells that harbor mutant KRAS. Suppression of TBK1 induced apoptosis specifically in human cancer cell lines that depend on oncogenic KRAS expression. In these cells, TBK1 activated NF- B anti-apoptotic signals involving cREL and BCL-XL that were essential for survival, providing mechanistic insights into this synthetic lethal interaction. These observations identify TBK1 as a potential therapeutic target in KRAS mutant tumors and establish a general approach for the rational identification of co-dependent pathways in cancer. Experiment Overall Design: Knock out of TBK1 in the contect of KRAS activation (mutant) and control (WT)
Project description:B-DNA-induced gene expression profile in wild-type, TBK1, IKKi(Ikbke), or TBK1 IKKi doubly deficient embryonic fibroblats; to elucidate how TBK1 and/or IKKi mediates B-DNA-mediated innate immune responses. Experiment Overall Design: Total RNA was extracted from embryonic fibroblats transfected for 4 h with or without poly(dA-dT)-poly(dT-dA), after which cRNA was synthesized. Preparation of cRNA, hybridization and scanning of the microarray were done according to the manufacturer's instructions (Affymetrix). A microarray (MG U74A version 2; Affymetrix) was used with Microarray Suite software (version 5.0; Affymetrix) and GeneSpring software (Silicon Genetics).
Project description:The process of regeneration by in vivo transdifferentiation in mammals is poorly understood. Here, using pancreatic β cell regeneration as a paradigm, we performed a single-cell transcriptomic study of in vivo transdifferentiation from adult mouse acinar cells to induced β cells.
Project description:We aimed to understand the functional roles of islet cellular oscillators under diabetic conditions and during β-cell regeneration. We assessed diurnal regulation of β-cell proliferation and the transcriptional landscape in α- and residual β-cells following β-cell ablation in Insulin-rtTA/TET-DTA mice that simultaneously expressed α- and β-cell specific fluorescent reports. The mouse pancreatic islets were isolated over 24-h with 4-h interval, followed by separation of α- and β- cells using FACS sorting, RNA extraction and RNA sequencing. Acute hyperglycemia and loss of β-cell mass perturbed absolute expression levels and temporal transcriptome profiles in residual β-cells, whereas in neighboring α-cells only changes in temporal profiles were observed. Strikingly, compensatory regeneration of β-cells exhibited circadian rhythmicity. In arrhythmic Bmal1 deficient mice, massive β-cell ablation led to aggravated hyperglycemia, hyperglucagonemia and a fatal diabetes. No compensatory proliferation of β-cells was observed in arrhythmic mice, suggesting an essential role of circadian clocks in β-cell regeneration.