Project description:Crosstalk between autophagy, host cell death, and inflammatory host responses to bacterial pathogens enables effective innate immune responses that limit bacterial growth while minimizing coincidental host damage. Mycobacterium tuberculosis (Mtb) thwarts innate immune defense mechanisms in alveolar macrophages (AMs) during the initial stages of infection and in recruited bone marrow-derived cells during later stages of infection. However, how protective inflammatory responses are achieved during Mtb infection and the variation of the response in different macrophage subtypes remain obscure. Here, we show that the autophagy receptor Tax1bp1 plays a critical role in enhancing inflammatory cytokine production and increasing the susceptibility of mice to Mtb infection. Surprisingly, although Tax1bp1 restricts Mtb growth during infection of bone marrow-derived macrophages (BMDMs) (Budzik et al. 2020) and terminates cytokine production in response to cytokine stimulation or viral infection, Tax1bp1 instead promotes Mtb growth in AMs, neutrophils, and a subset of recruited monocyte-derived cells from the bone marrow. Tax1bp1 also leads to increases in bacterial growth and inflammatory responses during infection of mice with Listeria monocytogenes, an intracellular pathogen that is not effectively targeted to canonical autophagy. In Mtb-infected AMs but not BMDMs, Tax1bp1 enhances necrotic-like cell death early after infection, reprogramming the mode of host cell death to favor Mtb replication in AMs. Tax1bp1’s impact on host cell death is a mechanism that explains Tax1bp1’s cell type-specific role in the control of Mtb growth. Similar to Tax1bp1-deficiency in AMs, the expression of phosphosite-deficient Tax1bp1 restricts Mtb growth. Together, these results show that Tax1bp1 plays a crucial role in linking the regulation of autophagy, cell death, and pro-inflammatory host responses and enhancing susceptibility to bacterial infection.
Project description:BioID2 Zebrafish Interaction Proteomics analyzed by nanoscale capillary LC coupled to a Fusion Lumos OT with label-free quantitation.
Project description:The fidelity of signal transmission requires the binding of regulatory molecules to their cognate targets. However, the crowded cell interior risks off-target interactions between proteins that are functionally unrelated. Understanding the constraints this imposes on cell systems evolution requires the fitness cost of spurious interactions to be quantified. Towards this end, we express human tyrosine kinases in the budding yeast S. cerevisiae. Yeast lacks bona fide tyrosine kinases and so the majority of resulting pY sites are functionless and artificial. We express 24 unique tyrosine kinases in total and perform phosphoproteomics in each case, resulting in ~30,000 phosphosites sites mapping to 3500 phosphoproteins. Examination of the fitness costs in each strain reveals a strong correlation between the number of spurious pY sites generated and negative effects on growth. Moreover, the prediction of pY effects on protein structure and on protein function (conservation-based) reveals potential for the widespread perturbation of the yeast proteome. Comparing the spurious pY sites (pre-selection) with native pY sites in human (post-selection) also demonstrates the recurrent modification of proteins and sites with no homology to native substrates. However, examination of these data together (fitness and phosphoproteomics) strongly suggests that a large number of the pY sites generated have a negligible effect on fitness. Finally, we test the hypothesis of pY counter-selection following the emergence of tyrosine kinases in metazoan species, but find no strong evidence for proteome-wide selection against spurious Y phosphorylation.
Project description:This study reports the first characterization of the intracellular proteome of peripheral blood mononuclear cells (PBMC) isolated from subjects diagnosed with primary open angle glaucoma (POAG)by shot-gun proteomics. Glaucoma is a chronic optic neuropathy and among the first causes of irreversible blindness on a global scale. Several recent data have pointed out alterations of immune system processes in glaucoma subjects. Very recently, oxygen consumption rate (OCR) and NAD levels have been proposed as biomarkers of disease severity.
Project description:Investigation of gene expression changes in a DvH genotype ES10-5, a strain isolated from population ES10 which has been evolved under salt stress for 5000 generations. The gene expression was compared to a gentype ES9-11 isolated from ES9 evolved under the same condition for 1200 generations and the ancestral strain. The genotype ES10-5 was characterized in this study. ES9-11 was isolated and characterized in Zhou A et al., 2013. Characterization of NaCl tolerance in Desulfovibrio vulgaris Hildenborough through experimental evolution. ISME J, 7(9), 1790-1802
Project description:Evolution of multicellular life forms has involved adaptation of organs that consist of multiple cell types, each with unique functional properties that as a collection, achieve complex organ function. Since each cell type is adapted to deliver specific functionality within the context of an organ, knowledge on functional landscapes occupied by individual cell types could improve comprehension of organ function at the molecular level. In kidney, podocytes and tubules are two cell types that work together, each with vastly different functional roles. Podocytes envelop the blood vessels in the glomerulus and act as filters while tubules, located downstream of the glomerulus, are responsible for reabsorption of important nutrients. Mitochondria hold a critical and well-studied role in tubules due to the high energetic requirements required to fulfill their function. In podocytes however, questions remain regarding the relevance of mitochondrial function in both normal physiology and pathology . Quantitative cross-linking mass spectrometry and proteomics together with a transgenic mitochondrial tagging strategy were used to investigate kidney cell-type specificity of mitochondria. These efforts revealed that despite similarities of podocyte and tubule mitochondrial proteomes, each contain unique features corresponding to known distinct functional roles. These include increased demand for energy production through the TCA cycle in tubules and increased detoxification demand in podocytes. Moreover, tubule and podocyte mitochondrial interactome differences revealed additional cell-type specific functional insights with alterations in betaine metabolism, lysine degradation, and other pathways not regulated through proteome abundance levels. Most importantly, these efforts illustrate that cell specific mitochondrial interactome differences within an organ can now be visualized. Therefore, this approach can generally be used to map cell-specific mitochondrial changes in disease, aging or even with therapy to better understand the roles and contributions of each cell type in normal physiology and pathology within an organ in ways not previously possible .
Project description:Label free quantititative phosphoproteomics analysis following TiO2 enrichment, nanoscale capillary chromatography and high resolution tandem mass spectrometry.
Project description:The CEBPA transcription factor is frequently mutated in acute myeloid leukemia (AML). Mutations in the CEBPA gene, which are typically biallelic, result in the production of a shorter isoform known as p30. Both the canonical 42-kDa isoform (p42) and the AML-associated p30 isoform bind chromatin and activate transcription, but the specific transcriptional programs controlled by each protein and how they are linked to a selective advantage in AML is not well understood. Here, we show that cells expressing the AML-associated p30 have reduced baseline inflammatory gene expression and display altered dynamics of transcriptional induction in response to LPS, consequently impacting cytokine secretion. This confers p30-expressing cells an increased resistance to the adverse effects of prolonged exposure to inflammatory signals. Mechanistically, we show that these differences primarily result from the differential regulation of AP-1 family proteins. In addition, we find that the altered function of the AP-1 member ATF4 in p30-expressing cells alters their response to ER stress. Collectively, these findings uncover a novel link between mutant CEBPA, inflammation and the stress response, potentially revealing a new vulnerability in AML.