TY - JOUR AB - The existence of N6-adenosine methylation (m6A) of mRNA has been known for a long time, but only recently its regulatory potential was uncovered. Current research deciphers the molecular determinants leading to the deposition of this modification and consequences for modified mRNAs. It also evaluates the importance of such modifications for specific cell types and programs. In this review, we summarize the current knowledge on m6A modification of mRNAs in conventional and regulatory T cells and T-cell-driven immune responses and pathology. We discuss the impact of m6A modification on T cell activation including cytokine and antigen receptor signaling or sensing of double-stranded RNAs (dsRNA). AU - Ito-Kureha, T.* AU - Heissmeyer, V. C1 - 66460 C2 - 53182 TI - Critical functions of N6-adenosine methylation of mRNAs in T cells. JO - Biochim. Biophys. Acta-Mol. Cell Res. VL - 1870 IS - 1 PY - 2023 SN - 0167-4889 ER - TY - JOUR AB - Ferroptosis is a necrotic form of cell death caused by inactivation of the glutathione system and uncontrolled iron-mediated lipid peroxidation. Increasing evidence implicates ferroptosis in a wide range of diseases from neurotrauma to cancer, highlighting the importance of identifying an executioner system that can be exploited for clinical applications. In this study, using pharmacological and genetic models of ferroptosis, we observed that lysosomal membrane permeabilization and cytoplasmic leakage of cathepsin B unleashes structural and functional changes in mitochondria and promotes a not previously reported cleavage of histone H3. Inhibition of cathepsin-B robustly rescued cellular membrane integrity and chromatin degradation. We show that these protective effects are independent of glutathione peroxidase-4 and are mediated by preventing lysosomal membrane damage. This was further confirmed when cathepsin B knockout primary fibroblasts remained unaffected in response to various ferroptosis inducers. Our work identifies new and yet-unrecognized aspects of ferroptosis and identifies cathepsin B as a mediator of ferroptotic cell death. AU - Nagakannan, P.* AU - Islam, M.I.* AU - Conrad, M. AU - Eftekharpour, E.* C1 - 60867 C2 - 49023 CY - Radarweg 29, 1043 Nx Amsterdam, Netherlands TI - Cathepsin B is an executioner of ferroptosis. JO - Biochim. Biophys. Acta-Mol. Cell Res. VL - 1868 IS - 3 PB - Elsevier PY - 2021 SN - 0167-4889 ER - TY - JOUR AB - Trypanosomatid parasites cause devastating African sleeping sickness, Chagas disease, and Leishmaniasis that affect about 18 million people worldwide. Recently, we showed that the biogenesis of glycosomes could be the "Achilles' heel" of trypanosomatids suitable for the development of new therapies against trypanosomiases. This was shown for inhibitors of the import machinery of matrix proteins, while the distinct machinery for the topogenesis of glycosomal membrane proteins evaded investigation due to the lack of a druggable interface. Here we report on the identification of the highly divergent trypanosomal PEX3, a central component of the transport machinery of peroxisomal membrane proteins and the master regulator of peroxisome biogenesis. The trypanosomatid PEX3 shows very low degree of conservation and its identification was made possible by a combinatory approach identifying of PEX19-interacting proteins and secondary structure homology screening. The trypanosomal PEX3 localizes to glycosomes and directly interacts with the membrane protein import receptor PEX19. RNAi-studies revealed that the PEX3 is essential and that its depletion results in mislocalization of glycosomal proteins to the cytosol and a severe growth defect. Comparison of the parasites and human PEX3-PEX19 interface disclosed differences that might be accessible for drug development. The absolute requirement for biogenesis of glycosomes and its structural distinction from its human counterpart make PEX3 a prime drug target for the development of novel therapies against trypanosomiases. The identification paves the way for future drug development targeting PEX3, and for the analysis of additional partners involved in this crucial step of glycosome biogenesis. AU - Kalel, V.C.* AU - Li, M.* AU - Gaussmann, S. AU - Delhommel, F. AU - Schaefer, A.* AU - Tippler, B.* AU - Jung, M.* AU - Maier, R.* AU - Oeljeklaus, S.* AU - Schliebs, W.* AU - Warscheid, B.* AU - Sattler, M. AU - Erdmann, R.* C1 - 57619 C2 - 47862 CY - Radarweg 29, 1043 Nx Amsterdam, Netherlands TI - Evolutionary divergent PEX3 is essential for glycosome biogenesis and survival of trypanosomatid parasites. JO - Biochim. Biophys. Acta-Mol. Cell Res. VL - 1866 IS - 12 PB - Elsevier PY - 2019 SN - 0167-4889 ER - TY - JOUR AB - The peroxisomal proteins (peroxins) that mediate the import of peroxisomal matrix proteins have been identified. Recently, the purification of a functional peroxisomal translocon has been reported. However, the molecular details of the import pathways and the mechanisms by which the cargo is translocated into the lumen of the organelle are still poorly understood. Structural studies have begun to provide insight into molecular mechanisms of peroxisomal import pathways for cargo proteins that harbor peroxisomal targeting signals, PTS1 and PTS2, at their C- and N-termini, respectively. So far structures have been reported for binary or tertiary protein-protein interfaces, and highlight the role of intrinsically disordered regions for these interactions. Here, we provide an overview of the currently available structural biology of peroxisomal import pathways. Current challenges and future perspectives of the structural biology of peroxisomal protein translocation are discussed. AU - Emmanouilidis, L. AU - Gopalswamy, M. AU - Passon, D.M.* AU - Wilmanns, M.* AU - Sattler, M. C1 - 47251 C2 - 40616 CY - Amsterdam SP - 804-813 TI - Structural biology of the import pathways of peroxisomal matrix proteins. JO - Biochim. Biophys. Acta-Mol. Cell Res. VL - 1863 IS - 5 PB - Elsevier Science Bv PY - 2016 SN - 0167-4889 ER - TY - JOUR AB - The correct topogenesis of peroxisomal membrane proteins is a crucial step for the formation of functioning peroxisomes. Although this process has been widely studied, the exact mechanism with which it occurs has not yet been fully characterized. Nevertheless, it is generally accepted that peroxisomes employ three proteins - Pex3, Pex19 and Pex16 in mammals - for the insertion of peroxisomal membrane proteins into the peroxisomal membrane. Structural biology approaches have been utilized for the elucidation of the mechanistic questions of peroxisome biogenesis, mainly by providing information on the architecture of the proteins significant for this process. This review aims to summarize, compare and put into perspective the structural knowledge that has been generated mainly for Pex3 and Pex19 and their interaction partners in recent years. AU - Giannopoulou, E.A.* AU - Emmanouilidis, L. AU - Sattler, M. AU - Dodt, G.* AU - Wilmanns, M.* C1 - 47257 C2 - 40617 CY - Amsterdam SP - 863-869 TI - Towards the molecular mechanism of the integration of peroxisomal membrane proteins. JO - Biochim. Biophys. Acta-Mol. Cell Res. VL - 1863 IS - 5 PB - Elsevier Science Bv PY - 2016 SN - 0167-4889 ER - TY - JOUR AB - The CATS protein (also known as FAM64A and RCS1) was first identified as a novel CALM (PICALM) interactor that influences the subcellular localization of the leukemogenic fusion protein CALM/AF10. CATS is highly expressed in cancer cell lines in a cell cycle dependent manner and is induced by mitogens. CATS is considered a marker for proliferation, known to control the metaphase-to-anaphase transition during the cell division. Using CATS as a bait in a yeast two-hybrid screen we identified the Kinase Interacting Stathmin (MS or UHMK1) protein as a CATS interacting partner. The interaction between CATS and KIS was confirmed by GST pull-down, co-immunopreciptation and co-localization experiments. Using kinase assay we showed that CATS is a substrate of KIS and mapped the phosphorylation site to CATS serine 131 (S131). Protein expression analysis revealed that KIS levels changed in a cell cycle-dependent manner and in the opposite direction to CATS levels. In a reporter gene assay KIS was able to enhance the transcriptional repressor activity of CATS, independent of CATS phophorylation at S131. Moreover, we showed that CATS and KIS antagonize the transactivation capacity of CALM/AF10.In summary, our results show that CATS interacts with and is a substrate for KIS, suggesting that KIS regulates CATS function. AU - Archangelo, L.F.* AU - Greif, P.A. AU - Maucuer, A.* AU - Manceau, V.* AU - Koneru, N. AU - Bigarella, C.L.* AU - Niemann, F.* AU - dos Santos, M.T.* AU - Kobarg, J.* AU - Bohlander, S.K. AU - Saad, S.T.O.* C1 - 24445 C2 - 31557 SP - 1269-1279 TI - The CATS (FAM64A) protein is a substrate of the Kinase Interacting Stathmin (KIS). JO - Biochim. Biophys. Acta-Mol. Cell Res. VL - 1833 IS - 5 PB - Elsevier Science PY - 2013 SN - 0167-4889 ER - TY - JOUR AB - Dominant mutations in the visual pigment Rhodopsin (Rh) cause retinitis pigmentosa (RP) characterized by progressive blindness and retinal degeneration. The most common Rh mutation, Rh(P23H) forms aggregates in the endoplasmic reticulum (ER) and impairs the proteasome; however, the mechanisms linking Rh aggregate formation to proteasome dysfunction and photoreceptor cell loss remain unclear. Using mammalian cell cultures, we provide the first evidence that misfolded Rh(P23H) is a substrate of the ERAD effector VCP, an ATP-dependent chaperone that extracts misfolded proteins from the ER and escorts them for proteasomal degradation. VCP co-localizes with misfolded Rh(P23H) in retinal cells and requires functional N-terminal and D1 ATPase domains to form a complex with Rh(P23H) aggregates. Furthermore, VCP uses its D2 ATPase activity to promote Rh(P23H) aggregate retrotranslocation and proteasomal delivery. Our results raise the possibility that modulation of VCP and ERAD activity might have potential therapeutic significance for RP. AU - Griciuc, A. AU - Aron, L.* AU - Piccoli, G. AU - Ueffing, M. C1 - 5983 C2 - 27765 SP - 424-434 TI - Clearance of Rhodopsin(P23H) aggregates requires the ERAD effector VCP. JO - Biochim. Biophys. Acta-Mol. Cell Res. VL - 1803 IS - 3 PB - Elsevier PY - 2010 SN - 0167-4889 ER - TY - JOUR AB - The evolutionary conserved protein Cdc48/VCP is involved in various cellular processes, such as protein degradation, membrane fusion and chaperone activity. Increased levels of Cdc48/VCP correlate with cancer, whereas Cdc48/VCP at endogenous levels has been proposed to be a pathological effector in protein deposition diseases. Upon mutation Cdc48/VCP triggers the multisystem disorder 'inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia' (IBMPFD). The roles of Cdc48/VCP under these diverse pathological conditions, especially its function in decreased and increased incidences of cell death underlying these diseases, are poorly understood. Mutation of yeast CDC48 (cdc48(S565G)) results in yeast cells demonstrating morphological markers of apoptotic cell death. In other species it has been confirmed that mutations and depletion of Cdc48/VCP cause apoptosis, whereas increased levels of this protein provide an anti-apoptotic effect. This review critically compares mechanisms of Cdc48/VCP-mediated apoptosis observed in yeast and other species. Cdc48/VCP plays a triple role in cell death. At first, loss-of-function of Cdc48/VCP due to mutation or depletion causes ER stress and oxidative stress, triggering apoptosis. Secondly, upon exogenously applied ER stress functional Cdc48/VCP is important in the processing of caspases and plays therewith a pro-apoptotic role. Finally, Cdc48/VCP protects cells from apoptosis through mediating and activating pro-survival signaling pathways, namely Akt and NFkappaB signaling. This complex role in cell death pathways could correspond with the various pathophysiological conditions Cdc48/VCP is involved in. AU - Braun, R.J. AU - Zischka, H. C1 - 3631 C2 - 25420 SP - 1418-1435 TI - Mechanisms of Cdc48/VCP-mediated cell death: From yeast apoptosis to human disease. JO - Biochim. Biophys. Acta-Mol. Cell Res. VL - 1783 IS - 7 PB - Elsevier PY - 2008 SN - 0167-4889 ER -