bims-nenemi Biomed News
on Neuroinflammation, neurodegeneration and mitochondria
Issue of 2024–10–06
seven papers selected by
Marco Tigano, Thomas Jefferson University
  1. Temporal alterations of the nascent proteome in response to mitochondrial stress.
  2. Integrated stress response plasticity governs normal cell adaptation to chronic stress via the PP2A-TFE3-ATF4 pathway.
  3. Mitotic ER-mitochondria contact enhances mitochondrial Ca2+ influx to promote cell division.
  4. SUMOylation of MFF coordinates fission complexes to promote stress-induced mitochondrial fragmentation.
  5. Longitudinal autophagy profiling of the mammalian brain reveals sustained mitophagy throughout healthy aging.
  6. Oncogenic KRAS drives immunosuppression of colorectal cancer by impairing DDX60-mediated dsRNA accumulation and viral mimicry.
  7. Alzheimer's disease-linked risk alleles elevate microglial cGAS-associated senescence and neurodegeneration in a tauopathy model.
  1. Cell Rep. 2024 Oct 02. pii: S2211-1247(24)01154-9. [Epub ahead of print]43(10): 114803
    Temporal alterations of the nascent proteome in response to mitochondrial stress.
    Tomasz M Stępkowski, Vanessa Linke, Dorota Stadnik, Maciej Zakrzewski, Anna E Zawada, Remigiusz A Serwa, Agnieszka Chacinska.
      Under stress, protein synthesis is attenuated to preserve energy and mitigate challenges to protein homeostasis. Here, we describe, with high temporal resolution, the dynamic landscape of changes in the abundance of proteins synthesized upon stress from transient mitochondrial inner membrane depolarization. This nascent proteome was altered when global translation was attenuated by stress and began to normalize as translation was recovering. This transition was associated with a transient desynchronization of cytosolic and mitochondrial translation and recovery of cytosolic and mitochondrial ribosomal proteins. Further, the elongation factor EEF1A1 was downregulated upon mitochondrial stress, and its silencing mimicked the stress-induced nascent proteome remodeling, including alterations in the nascent respiratory chain proteins. Unexpectedly, the stress-induced alterations in the nascent proteome were independent of physiological protein abundance and turnover. In summary, we provide insights into the physiological and pathological consequences of mitochondrial function and dysfunction.
    Keywords:  CP: Cell biology; CP: Metabolism; EEF1A; EEF1A1; cellular stress; elongation factor; mass spectrometry; mitochondria; nascent chain; protein synthesis; proteomics; translation
    DOI:  https://doi.org/10.1016/j.celrep.2024.114803
  2. Cell Death Differ. 2024 Sep 30.
    Integrated stress response plasticity governs normal cell adaptation to chronic stress via the PP2A-TFE3-ATF4 pathway.
    Rita A Avelar, Riya Gupta, Grace Carvette, Felipe da Veiga Leprevost, Medhasri Jasti, Jose Colina, Jessica Teitel, Alexey I Nesvizhskii, Caitlin M O'Connor, Maria Hatzoglou, Shirish Shenolikar, Peter Arvan, Goutham Narla, Analisa DiFeo.
      The integrated stress response (ISR) regulates cell fate during conditions of stress by leveraging the cell's capacity to endure sustainable and efficient adaptive stress responses. Protein phosphatase 2A (PP2A) activity modulation has been shown to be successful in achieving both therapeutic efficacy and safety across various cancer models. However, the molecular mechanisms driving its selective antitumor effects remain unclear. Here, we show for the first time that ISR plasticity relies on PP2A activation to regulate drug response and dictate cellular survival under conditions of chronic stress. We demonstrate that genetic and chemical modulation of the PP2A leads to chronic proteolytic stress and triggers an ISR to dictate whether the cell lives or dies. More specifically, we uncovered that the PP2A-TFE3-ATF4 pathway governs ISR cell plasticity during endoplasmic reticular and cellular stress independent of the unfolded protein response. We further show that normal cells reprogram their genetic signatures to undergo ISR-mediated adaptation and homeostatic recovery thereby avoiding toxicity following PP2A-mediated stress. Conversely, oncogenic specific cytotoxicity induced by chemical modulation of PP2A is achieved by activating chronic and irreversible ISR in cancer cells. Our findings propose that a differential response to chemical modulation of PP2A is determined by intrinsic ISR plasticity, providing a novel biological vulnerability to selectively induce cancer cell death and improve targeted therapeutic efficacy.
    DOI:  https://doi.org/10.1038/s41418-024-01378-3
  3. Cell Rep. 2024 Sep 28. pii: S2211-1247(24)01145-8. [Epub ahead of print]43(10): 114794
    Mitotic ER-mitochondria contact enhances mitochondrial Ca2+ influx to promote cell division.
    Gan Zhao, Mingkang Jia, Shicong Zhu, He Ren, Guopeng Wang, Guangwei Xin, Mengjie Sun, Xiangyang Wang, Qiaoyu Lin, Qing Jiang, Chuanmao Zhang.
      Cell division is tightly regulated and requires an expanded energy supply. However, how this energy is generated remains unclear. Here, we establish a correlation between two mitochondrial Ca2+ influx events and ATP production during mitosis. While both events promote ATP production during mitosis, the second event, the Ca2+ influx surge, is substantial. To facilitate this Ca2+ influx surge, the lamin B receptor (LBR) organizes a mitosis-specific endoplasmic reticulum (ER)-mitochondrial contact site (ERMCS), creating a rapid Ca2+ transport pathway. LBR acts as a tether, connecting the ER Ca2+ release channel IP3R with the mitochondrial VDAC2. Depletion of LBR disrupts the Ca2+ influx surge, reduces ATP production, and postpones the metaphase-anaphase transition and subsequent cell division. These findings provide insight into the mechanisms underlying mitotic energy production and supply required for cell proliferation.
    Keywords:  CP: Cell biology; CP: Metabolism; Ca(2+); ER-mitochondrial contact; LBR; VDAC2; cell cycle; cell division; energy generation; metaphase-anaphase transition; mitochondria; mitosis
    DOI:  https://doi.org/10.1016/j.celrep.2024.114794
  4. Sci Adv. 2024 Oct 04. 10(40): eadq6223
    SUMOylation of MFF coordinates fission complexes to promote stress-induced mitochondrial fragmentation.
    Richard Seager, Nitheyaa Shree Ramesh, Stephen Cross, Chun Guo, Kevin A Wilkinson, Jeremy M Henley.
      Mitochondria undergo fragmentation in response to bioenergetic stress, mediated by dynamin-related protein 1 (DRP1) recruitment to the mitochondria. The major pro-fission DRP1 receptor is mitochondrial fission factor (MFF), and mitochondrial dynamics proteins of 49 and 51 kilodaltons (MiD49/51), which can sequester inactive DRP1. Together, they form a trimeric DRP1-MiD-MFF complex. Adenosine monophosphate-activated protein kinase (AMPK)-mediated phosphorylation of MFF is necessary for mitochondrial fragmentation, but the molecular mechanisms are unclear. Here, we identify MFF as a target of small ubiquitin-like modifier (SUMO) at Lys151, MFF SUMOylation is enhanced following AMPK-mediated phosphorylation and that MFF SUMOylation regulates the level of MiD binding to MFF. The mitochondrial stressor carbonyl cyanide 3-chlorophenylhydrazone (CCCP) promotes MFF SUMOylation and mitochondrial fragmentation. However, CCCP-induced fragmentation is impaired in MFF-knockout mouse embryonic fibroblasts expressing non-SUMOylatable MFF K151R. These data suggest that the AMPK-MFF SUMOylation axis dynamically controls stress-induced mitochondrial fragmentation by regulating the levels of MiD in trimeric fission complexes.
    DOI:  https://doi.org/10.1126/sciadv.adq6223
  5. EMBO J. 2024 Oct 04.
    Longitudinal autophagy profiling of the mammalian brain reveals sustained mitophagy throughout healthy aging.
    Anna Rappe, Helena A Vihinen, Fumi Suomi, Antti J Hassinen, Homa Ehsan, Eija S Jokitalo, Thomas G McWilliams.
      Mitophagy neutralizes mitochondrial damage, thereby preventing cellular dysfunction and apoptosis. Defects in mitophagy have been strongly implicated in age-related neurodegenerative disorders such as Parkinson's and Alzheimer's disease. While mitophagy decreases throughout the lifespan of short-lived model organisms, it remains unknown whether such a decline occurs in the aging mammalian brain-a question of fundamental importance for understanding cell type- and region-specific susceptibility to neurodegeneration. Here, we define the longitudinal dynamics of basal mitophagy and macroautophagy across neuronal and non-neuronal cell types within the intact aging mouse brain in vivo. Quantitative profiling of reporter mouse cohorts from young to geriatric ages reveals cell- and tissue-specific alterations in mitophagy and macroautophagy between distinct subregions and cell populations, including dopaminergic neurons, cerebellar Purkinje cells, astrocytes, microglia and interneurons. We also find that healthy aging is hallmarked by the dynamic accumulation of differentially acidified lysosomes in several neural cell subsets. Our findings argue against any widespread age-related decline in mitophagic activity, instead demonstrating dynamic fluctuations in mitophagy across the aging trajectory, with strong implications for ongoing theragnostic development.
    Keywords:  Aging; Autophagy; Brain; Mitochondria; Mitophagy
    DOI:  https://doi.org/10.1038/s44318-024-00241-y
  6. Sci Immunol. 2024 Oct 04. 9(100): eado8758
    Oncogenic KRAS drives immunosuppression of colorectal cancer by impairing DDX60-mediated dsRNA accumulation and viral mimicry.
    Yi Zhou, Yaxin Zhang, Mingzhou Li, Tian Ming, Chao Zhang, Chengmei Huang, Jiexi Li, Fengtian Li, Huali Li, Enen Zhao, Feng Shu, Lingtao Liu, Xingyan Pan, Yijun Gao, Lin Tian, Libing Song, Huilin Huang, Wenting Liao.
      The interferon (IFN) response is vital for the effectiveness of immune checkpoint inhibition (ICI) therapy. Our previous research showed that KRAS (Kirsten rat sarcoma viral) mutation impairs the IFN response in colorectal cancer (CRC), with an unclear mechanism. Here, we demonstrate that KRAS accelerates double-stranded RNA (dsRNA) degradation, impairing dsRNA sensing and IFN response by down-regulating DExD/H-box helicase 6 (DDX60). DDX60 was identified as a KRAS target here and could bind to dsRNAs to protect against RNA-induced silencing complex (RISC)-mediated degradation. Overexpressing DDX60 induced dsRNA accumulation, reactivated IFN signaling, and increased CRC sensitivity to ICI therapy. Mechanistically, KRAS engaged the AKT (also known as protein kinase B)-GSK3β (glycogen synthase kinase-3 beta) pathway to suppress STAT3 phosphorylation, thereby inhibiting STAT3-driven DDX60 transcription. Our findings reveal a role for KRAS in dsRNA homeostasis, suggesting potential strategies to convert "cold" tumors to "hot" and to overcome ICI resistance in CRC with KRAS mutations.
    DOI:  https://doi.org/10.1126/sciimmunol.ado8758
  7. Neuron. 2024 Sep 24. pii: S0896-6273(24)00654-8. [Epub ahead of print]
    Alzheimer's disease-linked risk alleles elevate microglial cGAS-associated senescence and neurodegeneration in a tauopathy model.
    Gillian K Carling, Li Fan, Nessa R Foxe, Kendra Norman, Man Ying Wong, Daphne Zhu, Carlo Corona, Agnese Razzoli, Fangmin Yu, Allan Yarahmady, Pearly Ye, Hao Chen, Yige Huang, Sadaf Amin, Rebecca Sereda, Chloe Lopez-Lee, Emmanouil Zacharioudakis, Xiaoying Chen, Jielin Xu, Feixiong Cheng, Evripidis Gavathiotis, Ana Maria Cuervo, David M Holtzman, Sue-Ann Mok, Subhash C Sinha, Simone Sidoli, Rajiv R Ratan, Wenjie Luo, Shiaoching Gong, Li Gan.
      The strongest risk factors for late-onset sporadic Alzheimer's disease (AD) include the ε4 allele of apolipoprotein E (APOE), the R47H variant of triggering receptor expressed on myeloid cells 2 (TREM2), and female sex. Here, we combine APOE4 and TREM2R47H (R47H) in female P301S tauopathy mice to identify the pathways activated when AD risk is the strongest, thereby highlighting detrimental disease mechanisms. We find that R47H induces neurodegeneration in 9- to 10-month-old female APOE4 tauopathy mice. The combination of APOE4 and R47H (APOE4-R47H) worsened hyperphosphorylated tau pathology in the frontal cortex and amplified tauopathy-induced microglial cyclic guanosine monophosphate (GMP)-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling and downstream interferon response. APOE4-R47H microglia displayed cGAS- and BAX-dependent upregulation of senescence, showing association between neurotoxic signatures and implicating mitochondrial permeabilization in pathogenesis. By uncovering pathways enhanced by the strongest AD risk factors, our study points to cGAS-STING signaling and associated microglial senescence as potential drivers of AD risk.
    Keywords:  APOE; Alzheimer’s disease; R47H; TREM2; cGAS; inflammation; interferon; microglia; senescence; tau
    DOI:  https://doi.org/10.1016/j.neuron.2024.09.006
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