Project description:Group 3 Innate Lymphoid Cells (ILC3s) is important for maintaining intestinal homeostasis and host defense. Emerging studies have shown that metabolic regulation plays a crucial role in regulating ILC3 activation and function. However, the role of Liver Kinase B1 (LKB1), key metabolic regulator, in regulating ILC3 function and intestinal immunity remains poorly understood. In this study, we show that LKB1 is essential for ILC3 postnatal development, effector function, and intestinal immunity. Ablation of LKB1 in ILC3s results in reduced cell number due to increased apoptosis and reduced proliferation, which occurs at 2 -3 weeks after birth. In addition, LKB1 deletion leads to diminished IL-22 production and less protection against C.rodentium infection. Mechanistically, LKB1 deficiency led to impaired mitochondrial metabolism, as indicated by reduced glycolysis and oxidative phosphorylation and less mitochondrial mass. Together, our data demonstrate that LKB1 promotes ILC3 postnatal development and effector function to maintain intestinal immune homeostasis.
Project description:We have shown that removal of Lkb1 in chondorcytes results in enchondroma-like structure in postnatal mouse long bones. To furhter understand the role of Lkb1 in this process, we performed microarrrays to compare the transcriptional profile between control and conditional Lkb1 mutant (Col2a1-Cre; Lkb1c/c) chondrocytes. Postnatal day 30 mouse growth plate chondorcytes from control and mutant mouse femurs and tibiae were isolated for RNA extraction and hybridization on Affymetrix microarrays.
Project description:We have shown that removal of Lkb1 in chondorcytes results in enchondroma-like structure in postnatal mouse long bones. To furhter understand the role of Lkb1 in this process, we performed microarrrays to compare the transcriptional profile between control and conditional Lkb1 mutant (Col2a1-Cre; Lkb1c/c) chondrocytes.
Project description:Innate lymphoid cells (ILC) are tissue-resident effector cells with important roles in tissue homeostasis, protective immunity and inflammatory disease. Current nomenclature divides ILC into subsets based on the expression of master transcription factors and effector cytokine programs. In mucosal barrier tissues, group 3 ILC (ILC3) have been defined by the expression of the master transcription factor RORgt. However, ILC3 can be further subdivided into two major subsets – natural cytotoxicity receptor-expressing (NCR+) ILC3 and lymphoid tissue inducer (LTi)-like ILC3 which share type 3 effector modules but also exhibit significant ontological, transcriptional, phenotypic and functional heterogeneity. In particular, LTi-like ILC3 exhibit effector functions not typically associated with other RORgt-expressing lymphocytes, provoking the hypothesis that other master transcription factors may contribute to LTi-like ILC3 biology. Here we identify Bcl6 as an LTi-like ILC3 associated transcription factor in both mice and humans. Deletion of Bcl6 led to dysregulation of the LTi-like ILC3 transcriptional program and changes to subset-specific phenotypic markers and effector functions. Strikingly, loss of Bcl6 enhanced expression of the type 3 effector cytokines IL-17A and IL-17F in LTi-like ILC3, which was found to be in part dependent upon the commensal microbiota. Together these findings implicate Bcl6 as an ILC3 subset-defining transcription factor and part of a network that confers phenotype and function on LTi-like ILC3. Our study further provides a missing link to redefine analogous immune modules in innate and adaptive lymphocyte responses.
Project description:T helper 17 (Th17) cells are a distinct subset of CD4+ T cells necessary for maintaining gut homeostasis and have prominent roles in autoimmunity and inflammation1. Th17 cells have unique metabolic features, including a stem cell-like signature2,3 and reliance on mitochondrial respiratory chain function and tricarboxylic acid (TCA) cycle to coordinate metabolic and epigenetic remodeling4,5. Dynamic changes in mitochondrial membrane morphology are key to sustain organelle function6. However, it remains unclear whether mitochondrial membrane remodeling orchestrates metabolic and differentiation events in Th17 cells. Here we demonstrate that mitochondrial membrane fusion and tight cristae organization are required for Th17 cell function (i.e. cytokine expression) but dispensable in other T cell subsets. We find that Th17 cells rely on mitochondrial fusion as a result of their low metabolic activity. Thus, lowering metabolic activity in other T cell subsets by nutrient restriction was sufficient to increase reliance on mitochondrial fusion for effector function. Transcriptional, proteomic, and metabolomic profiling identified the serine/threonine kinase liver associated kinase B1 (LKB1) as an essential node coupling mitochondrial function to cytokine expression in T cells. By genetic and metabolomic approaches, we demonstrate that LKB1 regulates IL-17A expression by controlling TCA cycle metabolites and transcriptional remodeling. Th-17 cell-specific deletion of optic atrophy 1 (OPA1), a protein involved in mitochondrial inner membrane fusion and cristae organization, reduced autoimmune pathogenesis in a mouse model of multiple sclerosis, while additional deletion of LKB1 restored disease. Our findings highlight distinct mitochondrial requirements in CD4+ T cells, identify mitochondrial membrane fusion as a major determinant of Th17 responses, and reveal LKB1 as a sensor of mitochondrial integrity that links mitochondrial cues to effector programs in Th17 cells.
Project description:T helper 17 (Th17) cells are a distinct subset of CD4+ T cells necessary for maintaining gut homeostasis and have prominent roles in autoimmunity and inflammation1. Th17 cells have unique metabolic features, including a stem cell-like signature2,3 and reliance on mitochondrial respiratory chain function and tricarboxylic acid (TCA) cycle to coordinate metabolic and epigenetic remodeling4,5. Dynamic changes in mitochondrial membrane morphology are key to sustain organelle function6. However, it remains unclear whether mitochondrial membrane remodeling orchestrates metabolic and differentiation events in Th17 cells. Here we demonstrate that mitochondrial membrane fusion and tight cristae organization are required for Th17 cell function (i.e. cytokine expression) but dispensable in other T cell subsets. We find that Th17 cells rely on mitochondrial fusion as a result of their low metabolic activity. Thus, lowering metabolic activity in other T cell subsets by nutrient restriction was sufficient to increase reliance on mitochondrial fusion for effector function. Transcriptional, proteomic, and metabolomic profiling identified the serine/threonine kinase liver associated kinase B1 (LKB1) as an essential node coupling mitochondrial function to cytokine expression in T cells. By genetic and metabolomic approaches, we demonstrate that LKB1 regulates IL-17A expression by controlling TCA cycle metabolites and transcriptional remodeling. Th-17 cell-specific deletion of optic atrophy 1 (OPA1), a protein involved in mitochondrial inner membrane fusion and cristae organization, reduced autoimmune pathogenesis in a mouse model of multiple sclerosis, while additional deletion of LKB1 restored disease. Our findings highlight distinct mitochondrial requirements in CD4+ T cells, identify mitochondrial membrane fusion as a major determinant of Th17 responses, and reveal LKB1 as a sensor of mitochondrial integrity that links mitochondrial cues to effector programs in Th17 cells.
Project description:T helper 17 (Th17) cells are a distinct subset of CD4+ T cells necessary for maintaining gut homeostasis and have prominent roles in autoimmunity and inflammation1. Th17 cells have unique metabolic features, including a stem cell-like signature2,3 and reliance on mitochondrial respiratory chain function and tricarboxylic acid (TCA) cycle to coordinate metabolic and epigenetic remodeling4,5. Dynamic changes in mitochondrial membrane morphology are key to sustain organelle function6. However, it remains unclear whether mitochondrial membrane remodeling orchestrates metabolic and differentiation events in Th17 cells. Here we demonstrate that mitochondrial membrane fusion and tight cristae organization are required for Th17 cell function (i.e. cytokine expression) but dispensable in other T cell subsets. We find that Th17 cells rely on mitochondrial fusion as a result of their low metabolic activity. Thus, lowering metabolic activity in other T cell subsets by nutrient restriction was sufficient to increase reliance on mitochondrial fusion for effector function. Transcriptional, proteomic, and metabolomic profiling identified the serine/threonine kinase liver associated kinase B1 (LKB1) as an essential node coupling mitochondrial function to cytokine expression in T cells. By genetic and metabolomic approaches, we demonstrate that LKB1 regulates IL-17A expression by controlling TCA cycle metabolites and transcriptional remodeling. Th-17 cell-specific deletion of optic atrophy 1 (OPA1), a protein involved in mitochondrial inner membrane fusion and cristae organization, reduced autoimmune pathogenesis in a mouse model of multiple sclerosis, while additional deletion of LKB1 restored disease. Our findings highlight distinct mitochondrial requirements in CD4+ T cells, identify mitochondrial membrane fusion as a major determinant of Th17 responses, and reveal LKB1 as a sensor of mitochondrial integrity that links mitochondrial cues to effector programs in Th17 cells.