| 1. |
- Singh, Abeer Prakash, 1988, et al.
(författare)
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Molecular Connectivity of Mitochondrial Gene Expression and OXPHOS Biogenesis
- 2020
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Ingår i: Molecular Cell. - : Elsevier BV. - 1097-2765 .- 1097-4164. ; 79:6
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondria contain their own gene expression systems, including membrane-bound ribosomes dedicated to synthesizing a few hydrophobic subunits of the oxidative phosphorylation (OXPHOS) complexes. We used a proximity-dependent biotinylation technique, BiolD, coupled with mass spectrometry to delineate in baker's yeast a comprehensive network of factors involved in biogenesis of mitochondrial encoded proteins. This mitochondrial gene expression network (MiGENet) encompasses proteins involved in transcription, RNA processing, translation, or protein biogenesis. Our analyses indicate the spatial organization of these processes, thereby revealing basic mechanistic principles and the proteins populating strategically important sites. For example, newly synthesized proteins are directly handed over to ribosomal tunnel exit-bound factors that mediate membrane insertion, co-factor acquisition, or their mounting into OXPHOS complexes in a special early assembly hub. Collectively, the data reveal the connectivity of mitochondrial gene expression, reflecting a unique tailoring of the mitochondrial gene expression system.
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| 2. |
- Aufschnaiter, Andreas, et al.
(författare)
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Taking out the garbage : cathepsin D and calcineurin in neurodegeneration
- 2017
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Ingår i: Neural Regeneration Research. - : Medknow. - 1673-5374 .- 1876-7958. ; 12:11, s. 1776-1779
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Forskningsöversikt (refereegranskat)abstract
- Cellular homeostasis requires a tightly controlled balance between protein synthesis, folding and degradation. Especially long-lived, post-mitotic cells such as neurons depend on an efficient proteostasis system to maintain cellular health over decades. Thus, a functional decline of processes contributing to protein degradation such as autophagy and general lysosomal proteolytic capacity is connected to several age-associated neurodegenerative disorders, including Parkinson's, Alzheimer's and Huntington's diseases. These so called proteinopathies are characterized by the accumulation and misfolding of distinct proteins, subsequently driving cellular demise. We recently linked efficient lysosomal protein breakdown via the protease cathepsin D to the Ca2+/calmodulin-dependent phosphatase calcineurin. In a yeast model for Parkinson's disease, functional calcineurin was required for proper trafficking of cathepsin D to the lysosome and for recycling of its endosomal sorting receptor to allow further rounds of shuttling. Here, we discuss these findings in relation to present knowledge about the involvement of cathepsin D in proteinopathies in general and a possible connection between this protease, calcineurin signalling and endosomal sorting in particular. As dysregulation of Ca2+ homeostasis as well as lysosomal impairment is connected to a plethora of neurodegenerative disorders, this novel interplay might very well impact pathologies beyond Parkinson's disease.
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| 3. |
- Aufschnaiter, Andreas, et al.
(författare)
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The Coordinated Action of Calcineurin and Cathepsin D Protects Against alpha-Synuclein Toxicity
- 2017
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Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media SA. - 1662-5099. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The degeneration of dopaminergic neurons during Parkinson's disease (PD) is intimately linked to malfunction of alpha-synuclein (alpha Syn), the main component of the proteinaceous intracellular inclusions characteristic for this pathology. The cytotoxicity of alpha Syn has been attributed to disturbances in several biological processes conserved from yeast to humans, including Ca2+ homeostasis, general lysosomal function and autophagy. However, the precise sequence of events that eventually results in cell death remains unclear. Here, we establish a connection between the major lysosomal protease cathepsin D (CatD) and the Ca2+/calmodulin-dependent phosphatase calcineurin. In a yeast model for PD, high levels of human alpha Syn triggered cytosolic acidification and reduced vacuolar hydrolytic capacity, finally leading to cell death. This could be counteracted by overexpression of yeast CatD (Pep4), which re-installed pH homeostasis and vacuolar proteolytic function, decreased alpha Syn oligomers and aggregates, and provided cytoprotection. Interestingly, these beneficial effects of Pep4 were independent of autophagy. Instead, they required functional calcineurin signaling, since deletion of calcineurin strongly reduced both the proteolytic activity of endogenous Pep4 and the cytoprotective capacity of overexpressed Pep4. Calcineurin contributed to proper endosomal targeting of Pep4 to the vacuole and the recycling of the Pep4 sorting receptor Pep1 from prevacuolar compartments back to the trans-Golgi network. Altogether, we demonstrate that stimulation of this novel calcineurin-Pep4 axis reduces alpha Syn cytotoxicity.
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| 4. |
- Aufschnaiter, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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Yeast Mitoribosome Purification and Analyses by Sucrose Density Centrifugation and Immunoprecipitation
- 2023
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Ingår i: The Mitoribosome. - : Humana Press. - 9781071631706 - 9781071631713 ; , s. 119-132
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Mitochondrial protein biosynthesis is maintained by an interplay between the mitochondrial ribosome (mitoribosome) and a large set of protein interaction partners. This interactome regulates a diverse set of functions, including mitochondrial gene expression, translation, protein quality control, and respiratory chain assembly. Hence, robust methods to biochemically and structurally analyze this molecular machinery are required to understand the sophisticated regulation of mitochondrial protein biosynthesis. In this chapter, we present detailed protocols for immunoprecipitation, sucrose cushions, and linear sucrose gradients to purify and analyze mitoribosomes and their interaction partners.
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| 5. |
- Aufschnaiter, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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Yeast Mitoribosome Purification and Analyses by Sucrose Density Centrifugation and Immunoprecipitation
- 2023
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Ingår i: Methods in Molecular Biology. - : Humana Press. - 1064-3745 .- 1940-6029. ; , s. 119-132, s. 119-132
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Mitochondrial protein biosynthesis is maintained by an interplay between the mitochondrial ribosome (mitoribosome) and a large set of protein interaction partners. This interactome regulates a diverse set of functions, including mitochondrial gene expression, translation, protein quality control, and respiratory chain assembly. Hence, robust methods to biochemically and structurally analyze this molecular machinery are required to understand the sophisticated regulation of mitochondrial protein biosynthesis. In this chapter, we present detailed protocols for immunoprecipitation, sucrose cushions, and linear sucrose gradients to purify and analyze mitoribosomes and their interaction partners.
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| 6. |
- Berndtsson, Jens, et al.
(författare)
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Respiratory supercomplexes enhance electron transport by decreasing cytochrome c diffusion distance
- 2020
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Ingår i: Embo Reports. - : EMBO. - 1469-221X .- 1469-3178. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Respiratory chains are crucial for cellular energy conversion and consist of multi-subunit complexes that can assemble into supercomplexes. These structures have been intensively characterized in various organisms, but their physiological roles remain unclear. Here, we elucidate their function by leveraging a high-resolution structural model of yeast respiratory supercomplexes that allowed us to inhibit supercomplex formation by mutation of key residues in the interaction interface. Analyses of a mutant defective in supercomplex formation, which still contains fully functional individual complexes, show that the lack of supercomplex assembly delays the diffusion of cytochromec between the separated complexes, thus reducing electron transfer efficiency. Consequently, competitive cellular fitness is severely reduced in the absence of supercomplex formation and can be restored by overexpression of cytochromec. In sum, our results establish how respiratory supercomplexes increase the efficiency of cellular energy conversion, thereby providing an evolutionary advantage for aerobic organisms.
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| 7. |
- Dickinson, Q., et al.
(författare)
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Multi-omic integration by machine learning (MIMaL)
- 2022
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Ingår i: Bioinformatics. - : Oxford University Press (OUP). - 1367-4803 .- 1367-4811. ; 38:21, s. 4908-4918
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Tidskriftsartikel (refereegranskat)abstract
- Motivation: Cells respond to environments by regulating gene expression to exploit resources optimally. Recent advances in technologies allow for measuring the abundances of RNA, proteins, lipids and metabolites. These highly complex datasets reflect the states of the different layers in a biological system. Multi-omics is the integration of these disparate methods and data to gain a clearer picture of the biological state. Multi-omic studies of the proteome and metabolome are becoming more common as mass spectrometry technology continues to be democratized. However, knowledge extraction through the integration of these data remains challenging. Results: Connections between molecules in different omic layers were discovered through a combination of machine learning and model interpretation. Discovered connections reflected protein control (ProC) over metabolites. Proteins discovered to control citrate were mapped onto known genetic and metabolic networks, revealing that these protein regulators are novel. Further, clustering the magnitudes of ProC over all metabolites enabled the prediction of five gene functions, each of which was validated experimentally. Two uncharacterized genes, YJR120W and YDL157C, were accurately predicted to modulate mitochondrial translation. Functions for three incompletely characterized genes were also predicted and validated, including SDH9, ISC1 and FMP52. A website enables results exploration and also MIMaL analysis of user-supplied multi-omic data.
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| 8. |
- Gross, Angelina S., et al.
(författare)
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Acetyl-CoA carboxylase 1-dependent lipogenesis promotes autophagy downstream of AMPK
- 2019
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 294:32, s. 12020-12039
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Tidskriftsartikel (refereegranskat)abstract
- Autophagy, a membrane-dependent catabolic process, ensures survival of aging cells and depends on the cellular energetic status. Acetyl-CoA carboxylase 1 (Acc1) connects central energy metabolism to lipid biosynthesis and is rate-limiting for the de novo synthesis of lipids. However, it is unclear how de novo lipogenesis and its metabolic consequences affect autophagic activity. Here, we show that in aging yeast, autophagy levels highly depend on the activity of Acc1. Constitutively active Acc1 (acc1(S/A)) or a deletion of the Acc1 negative regulator, Snf1 (yeast AMPK), shows elevated autophagy levels, which can be reversed by the Acc1 inhibitor soraphen A. Vice versa, pharmacological inhibition of Acc1 drastically reduces cell survival and results in the accumulation of Atg8-positive structures at the vacuolar membrane, suggesting late defects in the autophagic cascade. As expected, acc1(S/A) cells exhibit a reduction in acetate/acetyl-CoA availability along with elevated cellular lipid content. However, concomitant administration of acetate fails to fully revert the increase in autophagy exerted by acc1(S/A). Instead, administration of oleate, while mimicking constitutively active Acc1 in WT cells, alleviates the vacuolar fusion defects induced by Acc1 inhibition. Our results argue for a largely lipid-dependent process of autophagy regulation downstream of Acc1. We present a versatile genetic model to investigate the complex relationship between acetate metabolism, lipid homeostasis, and autophagy and propose Acc1-dependent lipogenesis as a fundamental metabolic path downstream of Snf1 to maintain autophagy and survival during cellular aging.
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| 9. |
- Gross, Angelina S., et al.
(författare)
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Acetyl-CoA carboxylase 1–dependent lipogenesis promotes autophagy downstream of AMPK
- 2019
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Ingår i: Journal of Biological Chemistry. - : Elsevier. - 0021-9258 .- 1083-351X. ; 294:32, s. 12020-12039
-
Tidskriftsartikel (refereegranskat)abstract
- Autophagy, a membrane-dependent catabolic process, ensures survival of aging cells and depends on the cellular energetic status. Acetyl-CoA carboxylase 1 (Acc1) connects central energy metabolism to lipid biosynthesis and is rate-limiting for the de novo synthesis of lipids. However, it is unclear how de novo lipogenesis and its metabolic consequences affect autophagic activity. Here, we show that in aging yeast, autophagy levels highly depend on the activity of Acc1. Constitutively active Acc1 (acc1S/A) or a deletion of the Acc1 negative regulator, Snf1 (yeast AMPK), shows elevated autophagy levels, which can be reversed by the Acc1 inhibitor soraphen A. Vice versa, pharmacological inhibition of Acc1 drastically reduces cell survival and results in the accumulation of Atg8-positive structures at the vacuolar membrane, suggesting late defects in the autophagic cascade. As expected, acc1S/A cells exhibit a reduction in acetate/acetyl-CoA availability along with elevated cellular lipid content. However, concomitant administration of acetate fails to fully revert the increase in autophagy exerted by acc1S/A. Instead, administration of oleate, while mimicking constitutively active Acc1 in WT cells, alleviates the vacuolar fusion defects induced by Acc1 inhibition. Our results argue for a largely lipid-dependent process of autophagy regulation downstream of Acc1. We present a versatile genetic model to investigate the complex relationship between acetate metabolism, lipid homeostasis, and autophagy and propose Acc1-dependent lipogenesis as a fundamental metabolic path downstream of Snf1 to maintain autophagy and survival during cellular aging.
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| 10. |
- Kohler, Andreas, 1988-, et al.
(författare)
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Apitoxin and its components against cancer, neurodegeneration and rheumatoid arthritis : limitations and possibilities
- 2020
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Ingår i: Toxins. - : MDPI. - 2072-6651. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Natural products represent important sources for the discovery and design of novel drugs. Bee venom and its isolated components have been intensively studied with respect to their potential to counteract or ameliorate diverse human diseases. Despite extensive research and significant advances in recent years, multifactorial diseases such as cancer, rheumatoid arthritis and neurodegenerative diseases remain major healthcare issues at present. Although pure bee venom, apitoxin, is mostly described to mediate anti-inflammatory, anti-arthritic and neuroprotective effects, its primary component melittin may represent an anticancer therapeutic. In this review, we approach the possibilities and limitations of apitoxin and its components in the treatment of these multifactorial diseases. We further discuss the observed unspecific cytotoxicity of melittin that strongly restricts its therapeutic use and review interesting possibilities of a beneficial use by selectively targeting melittin to cancer cells.
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| 11. |
- Kohler, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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Mitochondrial lipids in neurodegeneration
- 2016
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Ingår i: Cell and Tissue Research. - : Springer. - 0302-766X .- 1432-0878. ; 367:1, s. 125-140
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Mitochondrial dysfunction is a common feature of many neurodegenerative diseases, including proteinopathies such as Alzheimer’s or Parkinson’s disease, which are characterized by the deposition of aggregated proteins in the form of insoluble fibrils or plaques. The distinct molecular processes that eventually result in mitochondrial dysfunction during neurodegeneration are well studied but still not fully understood. However, defects in mitochondrial fission and fusion, mitophagy, oxidative phosphorylation and mitochondrial bioenergetics have been linked to cellular demise. These processes are influenced by the lipid environment within mitochondrial membranes as, besides membrane structure and curvature, recruitment and activity of different proteins also largely depend on the respective lipid composition. Hence, the interaction of neurotoxic proteins with certain lipids and the modification of lipid composition in different cell compartments, in particular mitochondria, decisively impact cell death associated with neurodegeneration. Here, we discuss the relevance of mitochondrial lipids in the pathological alterations that result in neuronal demise, focussing on proteinopathies.
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| 12. |
- Kohler, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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The enzymatic core of the Parkinson’s disease-associated protein LRRK2 impairs mitochondrial biogenesis in aging yeast
- 2018
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Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media S.A.. - 1662-5099. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondrial dysfunction is a prominent trait of cellular decline during aging and intimately linked to neuronal degeneration during Parkinson’s disease (PD). Various proteins associated with PD have been shown to differentially impact mitochondrial dynamics, quality control and function, including the leucine-rich repeat kinase 2 (LRRK2). Here, we demonstrate that high levels of the enzymatic core of human LRRK2, harboring GTPase as well as kinase activity, decreases mitochondrial mass via an impairment of mitochondrial biogenesis in aging yeast. We link mitochondrial depletion to a global downregulation of mitochondria-related gene transcripts and show that this catalytic core of LRRK2 localizes to mitochondria and selectively compromises respiratory chain complex IV formation. With progressing cellular age, this culminates in dissipation of mitochondrial transmembrane potential, decreased respiratory capacity, ATP depletion and generation of reactive oxygen species. Ultimately, the collapse of the mitochondrial network results in cell death. A point mutation in LRRK2 that increases the intrinsic GTPase activity diminishes mitochondrial impairment and consequently provides cytoprotection. In sum, we report that a downregulation of mitochondrial biogenesis rather than excessive degradation of mitochondria underlies the reduction of mitochondrial abundance induced by the enzymatic core of LRRK2 in aging yeast cells. Thus, our data provide a novel perspective for deciphering the causative mechanisms of LRRK2-associated PD pathology.
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| 13. |
- Kohler, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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The vacuolar shapes of ageing : From function to morphology
- 2019
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Ingår i: Biochimica et Biophysica Acta. Molecular Cell Research. - : Elsevier. - 0167-4889 .- 1879-2596. ; 1866:5, s. 957-970
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Tidskriftsartikel (refereegranskat)abstract
- Cellular ageing results in accumulating damage to various macromolecules and the progressive decline of organelle function. Yeast vacuoles as well as their counterpart in higher eukaryotes, the lysosomes, emerge as central organelles in lifespan determination. These acidic organelles integrate enzymatic breakdown and recycling of cellular waste with nutrient sensing, storage, signalling and mobilization. Establishing physical contact with virtually all other organelles, vacuoles serve as hubs of cellular homeostasis. Studies in Saccharomyces cerevisiae contributed substantially to our understanding of the ageing process per se and the multifaceted roles of vacuoles/lysosomes in the maintenance of cellular fitness with progressing age. Here, we discuss the multiple roles of the vacuole during ageing, ranging from vacuolar dynamics and acidification as determinants of lifespan to the function of this organelle as waste bin, recycling facility, nutrient reservoir and integrator of nutrient signalling.
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| 14. |
- Kohler, Verena, 1992-, et al.
(författare)
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Closing the gap : membrane contact sites in the regulation of autophagy
- 2020
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Ingår i: Cells. - : MDPI. - 2073-4409. ; 9:5, s. 1184-1184
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Forskningsöversikt (refereegranskat)abstract
- In all eukaryotic cells, intracellular organization and spatial separation of incompatible biochemical processes is established by individual cellular subcompartments in form of membrane-bound organelles. Virtually all of these organelles are physically connected via membrane contact sites (MCS), allowing interorganellar communication and a functional integration of cellular processes. These MCS coordinate the exchange of diverse metabolites and serve as hubs for lipid synthesis and trafficking. While this of course indirectly impacts on a plethora of biological functions, including autophagy, accumulating evidence shows that MCS can also directly regulate autophagic processes. Here, we focus on the nexus between interorganellar contacts and autophagy in yeast and mammalian cells, highlighting similarities and differences. We discuss MCS connecting the ER to mitochondria or the plasma membrane, crucial for early steps of both selective and non-selective autophagy, the yeast-specific nuclear–vacuolar tethering system and its role in microautophagy, the emerging function of distinct autophagy-related proteins in organellar tethering as well as novel MCS transiently emanating from the growing phagophore and mature autophagosome.
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| 15. |
- Kohler, Verena, 1992-, et al.
(författare)
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Conjugative type IV secretion in Gram-positive pathogens : TraG, a lytic transglycosylase and endopeptidase, interacts with translocation channel protein TraM
- 2017
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Ingår i: Plasmid. - : Elsevier BV. - 0147-619X .- 1095-9890. ; 91, s. 9-18
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Tidskriftsartikel (refereegranskat)abstract
- Conjugative transfer plays a major role in the transmission of antibiotic resistance in bacteria. pIP501 is a Grampositive conjugative model plasmid with the broadest transfer host-range known so far and is frequently found in Enterococcus faecalis and Enterococcus faecium clinical isolates. The pIP501 type IV secretion system is encoded by 15 transfer genes. In this work, we focus on the VirB1-like protein TraG, a modular peptidoglycan metabolizing enzyme, and the VirB8-homolog TraM, a potential member of the translocation channel. By providing full-length traG in trans, but not with a truncated variant, we achieved full recovery of wild type transfer efficiency in the traG-knockout mutant E. faecalis pIP501AtraG. With peptidoglycan digestion experiments and tandem mass spectrometry we could assign lytic transglycosylase and endopeptidase activity to TraG, with the CHAP domain alone displaying endopeptidase activity. We identified a novel interaction between TraG and TraM in a bacterial 2-hybrid assay. In addition we found that both proteins localize in focal spots at the E. faecalis cell membrane using immunostaining and fluorescence microscopy. Extracellular protease digestion to evaluate protein cell surface exposure revealed that correct membrane localization of TraM requires the transmembrane helix of TraG. Thus, we suggest an essential role for TraG in the assembly of the pIP501 type IV secretion system.
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| 16. |
- Kohler, Verena, 1992-, et al.
(författare)
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TraN: A novel repressor of an Enterococcus conjugative type IV secretion system
- 2018
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Ingår i: Nucleic Acids Research. - : Oxford University Press. - 0305-1048 .- 1362-4962. ; 46:17, s. 9201-9219
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Tidskriftsartikel (refereegranskat)abstract
- The dissemination of multi-resistant bacteria represents an enormous burden on modern healthcare. Plasmid-borne conjugative transfer is the most prevalent mechanism, requiring a type IV secretion system that enables bacteria to spread beneficial traits, such as resistance to last-line antibiotics, among different genera. Inc18 plasmids, like the Gram-positive broad host-range plasmid pIP501, are substantially involved in propagation of vancomycin resistance from Enterococci to methicillin-resistant strains of Staphylococcus aureus. Here, we identified the small cytosolic protein TraN as a repressor of the pIP501-encoded conjugative transfer system, since deletion of traN resulted in upregulation of transfer factors, leading to highly enhanced conjugative transfer. Furthermore, we report the complex structure of TraN with DNA and define the exact sequence of its binding motif. Targeting this protein–DNA interaction might represent a novel therapeutic approach against the spreading of antibiotic resistances.
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| 17. |
- Aufschnaiter, Andreas, et al.
(författare)
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Fließbandfertigung von Atmungskettenkomplexen in Mitochondrien : Assembly line production of respiratory chain complexes in mitochondria
- 2022
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Ingår i: BioSpektrum. - : Springer Science and Business Media LLC. - 0947-0867 .- 1868-6249. ; 28:4, s. 366-369
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Forskningsöversikt (refereegranskat)abstract
- A key function of mitochondria consists of energy conversion, performed with the help of the respiratory chain and the ATP synthase. Biogenesis of these essential molecular machines requires expression of nuclear and mitochondrially encoded genes. We describe our current understanding how these processes are coordinated and how they are organized in specific areas of the inner membrane to facilitate the assembly of these sophisticated complexes.
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| 18. |
- Aufschnaiter, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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Fließbandfertigung von Atmungskettenkomplexen in Mitochondrien
- 2022
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Ingår i: BIOspektrum. - : Springer Nature. - 0947-0867 .- 1868-6249. ; 28:4, s. 366-369
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A key function of mitochondria consists of energy conversion, performed with the help of the respiratory chain and the ATP synthase. Biogenesis of these essential molecular machines requires expression of nuclear and mitochondrially encoded genes. We describe our current understanding how these processes are coordinated and how they are organized in specific areas of the inner membrane to facilitate the assembly of these sophisticated complexes.
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| 19. |
- Aufschnaiter, Andreas, Dr. rer. nat. 1988-, et al.
(författare)
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Peroxisomal fission controls yeast life span
- 2015
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Ingår i: Cell Cycle. - : Taylor & Francis. - 1538-4101 .- 1551-4005. ; 14:15, s. 2389-2390
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Tidskriftsartikel (refereegranskat)
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| 20. |
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| 21. |
- Ebrahimi, Mahsa, 1985-, et al.
(författare)
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Phosphate Restriction Promotes Longevity via Activation of Autophagy and the Multivesicular Body Pathway
- 2021
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Ingår i: Cells. - : MDPI. - 2073-4409. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- Nutrient limitation results in an activation of autophagy in organisms ranging from yeast, nematodes and flies to mammals. Several evolutionary conserved nutrient-sensing kinases are critical for efficient adaptation of yeast cells to glucose, nitrogen or phosphate depletion, subsequent cell-cycle exit and the regulation of autophagy. Here, we demonstrate that phosphate restriction results in a prominent extension of yeast lifespan that requires the coordinated activity of autophagy and the multivesicular body pathway, enabling efficient turnover of cytoplasmic and plasma membrane cargo. While the multivesicular body pathway was essential during the early days of aging, autophagy contributed to long-term survival at later days. The cyclin-dependent kinase Pho85 was critical for phosphate restriction-induced autophagy and full lifespan extension. In contrast, when cell-cycle exit was triggered by exhaustion of glucose instead of phosphate, Pho85 and its cyclin, Pho80, functioned as negative regulators of autophagy and lifespan. The storage of phosphate in form of polyphosphate was completely dispensable to in sustaining viability under phosphate restriction. Collectively, our results identify the multifunctional, nutrient-sensing kinase Pho85 as critical modulator of longevity that differentially coordinates the autophagic response to distinct kinds of starvation.
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| 22. |
- Habernig, Lukas, et al.
(författare)
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Ca2+ administration prevents alpha-synuclein proteotoxicity by stimulating calcineurin-dependent lysosomal proteolysis
- 2021
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 17:11
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Tidskriftsartikel (refereegranskat)abstract
- The capacity of a cell to maintain proteostasis progressively declines during aging. Virtually all age-associated neurodegenerative disorders associated with aggregation of neurotoxic proteins are linked to defects in the cellular proteostasis network, including insufficient lysosomal hydrolysis. Here, we report that proteotoxicity in yeast and Drosophila models for Parkinson’s disease can be prevented by increasing the bioavailability of Ca2+, which adjusts intracellular Ca2+ handling and boosts lysosomal proteolysis. Heterologous expression of human α-synuclein (αSyn), a protein critically linked to Parkinson’s disease, selectively increases total cellular Ca2+ content, while the levels of manganese and iron remain unchanged. Disrupted Ca2+ homeostasis results in inhibition of the lysosomal protease cathepsin D and triggers premature cellular and organismal death. External administration of Ca2+ reduces αSyn oligomerization, stimulates cathepsin D activity and in consequence restores survival, which critically depends on the Ca2+/calmodulin-dependent phosphatase calcineurin. In flies, increasing the availability of Ca2+ discloses a neuroprotective role of αSyn upon manganese overload. In sum, we establish a molecular interplay between cathepsin D and calcineurin that can be activated by Ca2+ administration to counteract αSyn proteotoxicity.
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| 23. |
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| 24. |
- Habernig, Lukas, et al.
(författare)
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Ca2+ administration prevents α-synuclein proteotoxicity by stimulating calcineurin-dependent lysosomal proteolysis
- 2021
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 17:11
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Tidskriftsartikel (refereegranskat)abstract
- The capacity of a cell to maintain proteostasis progressively declines during aging. Virtually all age-associated neurodegenerative disorders associated with aggregation of neurotoxic proteins are linked to defects in the cellular proteostasis network, including insufficient lysosomal hydrolysis. Here, we report that proteotoxicity in yeast and Drosophila models for Parkinson's disease can be prevented by increasing the bioavailability of Ca2+, which adjusts intracellular Ca2+ handling and boosts lysosomal proteolysis. Heterologous expression of human α-synuclein (αSyn), a protein critically linked to Parkinson's disease, selectively increases total cellular Ca2+ content, while the levels of manganese and iron remain unchanged. Disrupted Ca2+ homeostasis results in inhibition of the lysosomal protease cathepsin D and triggers premature cellular and organismal death. External administration of Ca2+ reduces αSyn oligomerization, stimulates cathepsin D activity and in consequence restores survival, which critically depends on the Ca2+/calmodulin-dependent phosphatase calcineurin. In flies, increasing the availability of Ca2+ discloses a neuroprotective role of αSyn upon manganese overload. In sum, we establish a molecular interplay between cathepsin D and calcineurin that can be activated by Ca2+ administration to counteract αSyn proteotoxicity.
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| 25. |
- Leibiger, Christine, et al.
(författare)
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Endolysosomal pathway activity protects cells from neurotoxic TDP-43
- 2018
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Ingår i: Microbial Cell. - : Shared Science Publishers OG. - 2311-2638. ; 5:4, s. 212-214
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The accumulation of protein aggregates in neurons is a typical pathological hallmark of the motor neuron disease amyotrophic lateral sclerosis (ALS) and of frontotemporal dementia (FTD). In many cases, these aggregates are composed of the 43 kDa TAR DNA-binding protein (TDP‑43). Using a yeast model for TDP‑43 proteinopathies, we observed that the vacuole (the yeast equivalent of lysosomes) markedly contributed to the degradation of TDP‑43. This clearance occurred via TDP‑43-containing vesicles fusing with the vacuole through the concerted action of the endosomal-vacuolar (or endolysosomal) pathway and autophagy. In line with its dominant role in the clearance of TDP‑43, endosomal-vacuolar pathway activity protected cells from the detrimental effects of TDP‑43. In contrast, enhanced autophagy contributed to TDP‑43 cytotoxicity, despite being involved in TDP‑43 degradation. TDP‑43’s interference with endosomal-vacuolar pathway activity may have two deleterious consequences. First, it interferes with its own degradation via this pathway, resulting in TDP‑43 accumulation. Second, it affects vacuolar proteolytic activity, which requires endosomal-vacuolar trafficking. We speculate that the latter contributes to aberrant autophagy. In sum, we propose that ameliorating endolysosomal pathway activity enhances cell survival in TDP‑43-associated diseases.
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