Project description:Tau pathology is a major hallmark of Alzheimer’s disease (AD) and related diseases, called tauopathies. While Tau is normally enriched in axons, somatodendritic missorting of the microtubule-associated protein is a key event in early disease development. Tau missorting promotes synaptic loss and neuronal dysfunction but the mechanisms underlying both normal axonal sorting and pathological missorting remain unclear. Interestingly, the disease-associated Tau brain isoforms show different axodendritic distribution, but the distinct role of these isoforms in health and disease largely unknown. Here, we aimed to identify domains or motifs of Tau and cellular binding partners that are required for efficient axonal Tau sorting, and we studied the differences of the isoform-specific Tau interactome. By using human MAPT-KO induced pluripotent stem cell (iPSC)-derived glutamatergic neurons, we analyzed the sorting behavior of more than 20 truncated or phosphorylation-mutant Tau constructs, and we used TurboID-based proximity labelling and proteomics to identify sorting- and isoform-specific Tau interactors. We found that efficient axonal Tau sorting was independent of the N-terminal tail, the C-terminal repeat domains, and the general microtubule affinity of Tau. In contrast, the presence of the proline-rich region 2 (PRR2) was necessary for successful sorting. Our interactome data revealed peroxisomal accumulation of the Tau N-terminal half, while axonal Tau interacted with the PP2A activator HSP110. When we compared the interactome of 0N3R- and 0N4R-Tau, we observed specific interactions of 0N4R-Tau with regulators of presynaptic exocytosis and postsynaptic plasticity, which are partially associated with AD pathogenesis, such as members of the CDC42 pathway and the RAB11 proteins, while 0N3R-Tau bound to MAP4 and other cytoskeletal elements. In sum, our study postulates that axonal Tau sorting relies on the PRR2 domain but not on microtubule affinity, and unravels a potential isoform-specific role in synaptic function and AD-related dysfunction.
Project description:This project aims to identify novel regulators of mtDNA turnover, for what we used TurboID. For specific detection of the mitochondria-endosome proteome, we fused the N-terminal part of Turbo ID to RAB5C (TurboID aa1-aa72; RAB5C-SplitTurboNt-V5) and, the C-terminal part to SAMM50 (TurboID aa73–aa246; SAMM50-SplitTurboCt-HA). Proximity biotinylation was performed in transduced HEK293 cells expressing Split TurboID constructs. Cells expressing only SAMM50-SplitC-HA were used as a negative control. For protein isolation, HEK293 cells were incubated for 4 h with 0,25 mM biotin. For inducing mtDNA damage, cells were previously transfected with Twinkle K319E-Cherry 24 h before the biotin incubation.
Project description:Interactome of overexpressed, HA-tagged AIFM1 in HEK293T AIFM1 KO background vs control (3797, 3593), Interactome of overexpressed, HA-tagged AIFM1 variants in HEK293T AIFM1 KO background vs control (3859), Comparison of whole cell extract after gelfiltration of HEK293T AIFM1 KO cell line vs WT
Project description:This project includes two proximity labeling experiments, one to establish the vicinity of UNC-45 under non-stress conditions and one to examine changes in the vicinity of UNC-45 under optogenetically induced mechanical muscle stress. The first non-stress experiment consists of 15 samples after biotin-streptavidin pull-down in 5 replicates of 3 conditions (3 transgenic C. elegans strains). Transgenic C. elegans strains expressing the mutant BirA biotin ligases miniTurbo and TurboID in body wall muscle cells were used to compare a proximity-labeled strain expressing an UNC-45-miniTurbo-2xHA fusion protein in the muscle cells (PP3135 unc-119(ed4)III; hhIs241[unc-54p::unc-45::miniTurbo::2xHA; unc-119(+)]) with a strain expressing the biotin ligase TurboID-2xHA without fusion protein in muscle cells (PP3138 unc-119(ed4)III; hhIs242[unc-54p::TurboID::2xHA; unc-119(+)]) to find transient interactors of the myosin chaperone UNC-45 in muscle. As a control, we included a strain expressing a transgenic UNC-45-FLAG protein in the body wall muscle (PP1017 unc-119(ed4)III; hhIs84[unc-119(+); unc-54p::unc-45::FLAG]). Biotinylated proteins in 2.5 mg lysates of these strains were pulled down with streptavidin sepharose beads and identified by mass spectrometry. The second mechanical stress experiment consists of 10 samples after biotin-streptavidin pull-down in 5 replicates of 2 conditions. A transgenic C. elegans strain expressing the biotin ligase miniTurbo fused to UNC-45 in body wall muscle cells was crossed with a transgenic strain expressing the optogenetic channelrhodopsin mutant ChR2(C128S;H134R)-FLAG in body wall muscle cells (PP3358 hhIs241[unc-54p::unc-45::miniTurbo::2xHA; unc-119(+)]; hhIs251[myo-3p::ChR2(C128S,H134R)-FLAG::unc-54 3'UTR, Cbrunc-119(+)]). The latter transgene is used to contract the worms’ muscles by blue light illumination to induce mechanical muscle stress. The optogenetic channel is activated by adding the cofactor all-trans retinal (ATR) to its food source E. coli OP50. In this experiment, we compared proximity-labeling in the UNC-45-miniTurbo-2xHA expressing strain under conditions with ATR (L+, treatment, contraction) with proximity-labeling in the UNC-45-miniTurbo-2xHA expressing strain under conditions without ATR (L-, control, no contraction) to find transient interactors of the candidate UNC-45 in muscle under mechanical stress. Biotinylated proteins in 2.5 mg of lysates of these strains were pulled down using streptavidin sepharose beads and identified by mass spectrometry.
Project description:Identification of whole proteome changes in Purkinje cells of the cerebellum of AP-2 cKo and control mice at 2 months of age after APEX AAV injection
Project description:We overexpressed eGFP, eGFP-SPP and pmRFP-Q74 construct in HEK93 cells. We made immunoprecipitation of GFP. We compare the interactome of eGFP and eGFP-SPP.
Project description:This project includes 16 samples of transgenic C. elegans whole worm lysate after mechanical stress in 4 replicates of 4 conditions. Transgenic C. elegans strains expressing the optogenetic channelrhodopsin mutant ChR2(C128S;H134R)-FLAG in body wall muscle cells (PP3189 hhIs251[myo-3p::ChR2(C128S,H134R)-FLAG::unc-54 3'UTR, Cbrunc-119(+)]) were used to contract the worms’ muscles by blue light illumination to induce mechanical muscle stress. The optogenetic channel is activated by adding the cofactor all-trans retinal (ATR) to it’s food source E. coli OP50. In this experiment, we compared the treatment condition (1) worms after 8 h of illumination on plates with ATR (light plus ATR) to three control conditions: (2) illumination on plates without ATR (light minus ATR), (3) worms kept in the dark on plates with ATR (dark plus ATR), and (4) worms kept in the dark on plates without ATR (dark minus ATR).
Project description:This project includes 20 samples after immunoprecipitation of C. elegans myosin heavy chain B (MHC B/UNC-54/F11C3.3, UniProt P02566 with a Gly387Arg mutation) in 4 replicates of 4 conditions. Lysates from a myosin-misfolding C. elegans strain (unc-54(e1301) with a Gly387Arg substitution in MHC B) grown on (A) control RNAi, (B) RNAi against nhl-1 (F54G8.4), (C) RNAi against F40A3.6, and (D) RNAi against nhl-1 and F40A3.6 together were used for immunoprecipitation. Samples from groups A, B, C and D were incubated over night at 4°C with 1 µg of a mouse monoclonal hybridoma antibody against MHC B (mAb 5-8 from the Developmental Studies Hybridoma Bank, DSHB), while 4 lysate samples from unc-54(e1301) worms on control RNAi (Z) were incubated WITHOUT antibody addition. The next day, co-immunoprecipitated proteins were collected on magnetic Dynabeads Protein A for 2 h at 4°C, washed, on-bead digested, and subjected to identification by mass spectrometry.
Project description:Mitochondria play a crucial role in regulating cellular homeostasis in response to intrinsic and extrinsic cues by changing cellular metabolism to meet these challenges. However, the molecular underpinnings of this regulation and the complete spectrum of these physiological outcomes remain largely unexplored. In this study, we elucidate the mechanisms driving the whitening phenotype in brown adipose tissue (BAT) deficient in the mitochondrial matrix protease CLPP. We find that CLPP-deficient BAT shows aberrant accumulation of lipid droplets, which occurs independently of defects in oxygen consumption and fatty acid oxidation. Our results indicate that mitochondrial dysfunction due to CLPP deficiency leads to the build-up of the oncometabolite 2-hydroxyglutarate (2-HG), which in turn promotes lipid droplet enlargement. We further demonstrate that 2-HG influences gene expression and decreases nuclear stiffness by modifying epigenetic signatures. We propose that lipid accumulation and altered nuclear stiffness regulated through 2-HG are novel stress responses to mitochondrial dysfunction.