ABSTRACT: Human filamin C (FLNc) is a target of the protease calpain at Y2625. To confirm the dependency of calpain cleavage from FLNc phosphorylation at position S2623/S2624 by PKCa, FLNc was overexpressed in HEK293 cells and cells were treated with PMA to stimulated kinase activity, with Gö6976 to inhibit kinase activity or mock-treated with DMSO. Subsequently, recombinant calpain-1 and GluC were used and the resulting peptide TVTSSSSRGSSY was monitored by SRM analyses.
Project description:Human filamin C (FLNc) is a target of the protease calpain at Y2625. To confirm the dependency of calpain cleavage from FLNc phosphorylation at position S2623/S2624 by PKCa, FLNc was overexpressed in HEK293 cells and cells were treated with PMA to stimulated kinase activity, with Gö6976 to inhibit kinase activity or mock-treated with DMSO. Subsequently, recombinant calpain-1 and GluC were used and the resulting peptide TVTSSSSRGSSY was monitored by SRM analyses.
Project description:Skeletal muscle is known to adapt dynamically to changes in workload by regulatory processes of the phosphatidylinositide 3-kinase (PI3K)/Akt pathway. We performed a global quantitative phosphoproteomics analysis of contracting mouse C2 myotubes treated with insulin growth factor 1 (IGF-1) or LY294002 to activate or inhibit PI3K/Akt signaling, respectively. Among the significantly regulated phosphopeptides we identified the novel extended basophilic motif RxRxxp[S/T]xxp[S] to be enriched in the set of down-regulated phosphopeptides following inhibition of PI3K/Akt signaling. Using literature-based text mining we identified the kinases Akt, serum and glucocorticoid-regulated kinase 1 (SGK1) and p70S6 kinase to be potentially involved in the phosphorylation of the first serine in the RxRxxp[S/T]xxp[S] motif, whereas no kinase targeting the serine in the +3 position was revealed. In the signaling adapter protein filamin c (FLNc) we found this novel motif in immunoglobulin (Ig)-like domain 20 which is involved in various protein interactions. Through in vitro and in cellulo kinase assays we identified Akt and protein kinase C alpha as the responsible kinases phosphorylating FLNc in this motif at the first and the second serine, respectively.
Project description:FLNc, the muscle-specific isoform of the filamin family, is a multi-adaptor protein, comprising 1 amino-terminal actin-binding (ABD) domain followed by 24 immunoglobulin-like (Ig) domains. While FLNc can form homodimers via the last Ig-like domain and thus function as an actin-crosslinker like the other filamins, it features a unique insertion of 82 amino acids (aa) in domain 20. This insert was not only shown to mediate the interaction to several FLNc binding partners, but also to contain an Akt-mediated phosphorylation site at S2234 of mouse FLNc (mFLNc). To reveal novel proteins in the nano-environment of FLNc within myotubes under mild electrical pulse stimulation conditions, we applied a quantitative BioID appraoch.
Project description:The Z-disc is a protein-rich structure critically important for myofibril development and integrity. Since a role of the Z-disc for signal integration and transduction was recently suggested, its precise phosphorylation landscape warranted in-depth analysis. We therefore established a site-resolved protein phosphorylation map of the Z-disc in skeletal myocytes and found that it is a phosphorylation hotspot in living cells, underscoring its functions in signalling and disease-related processes. In an exemplary fashion, we analysed the actin-binding multi-adaptor protein filamin C (FLNc), which is essential for Z-disc assembly and maintenance, and found that PKC phosphorylation at distinct serine residues in its hinge 2 region prevents its cleavage at an adjacent tyrosine residue by calpain 1. With this quantitative in vivo kinase assay, we show that the phosphorylation site S2625 in mouse FLNc is significantly down-regulated upon treatment of C2C12 myotubes with the PKCα inhibitor Gö6976.
Project description:This project was designed to identify a difference in the binding affinity of FILIP1 to different FLNc variants. To this end FLNc domain 1-3 and FLNc d18-21 were used as bait for a pull-down analysis.
Project description:Filamin C (encoded by the FLNC gene) is a large actin-cross-linking protein involved in shaping the actin cytoskeleton in response to signaling events both at the sarcolemma and at myofibrillar Z-discs of cross-striated muscle cells. Multiple mutations in FLNC are associated with myofibrillar myopathies of autosomal dominant inheritance. Here, we describe a boy with congenital onset of generalized muscular hypotonia and muscular weakness, delayed motor development but no cardiac involvement associated with a homozygous FLNC mutation affecting the rod domain of the protein. To demonstrate pathogenicity of this homozygous FLNC-mutation described, ultra-morphological, proteomic and functional investigations were performed in addition to immunological studies of known marker proteins for dominant filaminopathies. Our results showed that the mutant protein is expressed to similar quantities as the wildtype variant in control skeletal muscle fibres, alters the proteomic signature of quadriceps muscle, and results in the presence of ultrastructural perturbations. Moreover, comparable findings for filaminopathy marker proteins were found in both, our homozygous and a dominant case. The mutant protein is less stable and more prone to degradation by proteolytic enzymes than the wildtype variant. These combined findings extend the currently recognized clinical, genetic and biochemical spectrum of filaminopathies. The unusual congenital presentation of the disease indicates that homozygosity for a mutation in filamin C severely aggravates the phenotype.
Project description:Amphotericin B (AMB) is the most widely used polyene antifungal drug for the treatment of systemic fungal infections including invasive aspergillosis. We aimed to understand molecular targets of AMB in Aspergillus fumigatus (Afu) by genomic approaches. Amphotericin B (AMB) is the most widely used polyene antifungal drug for the treatment of systemic fungal infections including invasive aspergillosis. We aimed to understand molecular targets of AMB in Aspergillus fumigatus (Afu) by microarray and proteomic methods. Keywords: Aspergillus fumigatus treated with amphotericin B for 24 hours Experiment was performed in dye swap manner from two different biological replicates
Project description:Transcriptional profiling of calpain-6-deficient murine bone marrow-derived macrophages comparing with calpain-6 wild-type macrophages. Total RNA was extracted from the pooled cells. Two-condition experiment, wild-type macrophages vs. calpain-6-deficiennt macrophages. The cells were derived from four mice, and were pooled for analysis.