bims-lycede 2024-08-11 papers

Issue of 2024‒08‒11
four papers selected by
Sofía Peralta, Universidad Nacional de Cuyo

EMBO J. 2024 Aug 05.

Lysosomal TBK1 responds to amino acid availability to relieve Rab7-dependent mTORC1 inhibition.

Gabriel Talaia, Amanda Bentley-DeSousa, Shawn M Ferguson.

Lysosomes play a pivotal role in coordinating macromolecule degradation and regulating cell growth and metabolism. Despite substantial progress in identifying lysosomal signaling proteins, understanding the pathways that synchronize lysosome functions with changing cellular demands remains incomplete. This study uncovers a role for TANK-binding kinase 1 (TBK1), well known for its role in innate immunity and organelle quality control, in modulating lysosomal responsiveness to nutrients. Specifically, we identify a pool of TBK1 that is recruited to lysosomes in response to elevated amino acid levels. This lysosomal TBK1 phosphorylates Rab7 on serine 72. This is critical for alleviating Rab7-mediated inhibition of amino acid-dependent mTORC1 activation. Furthermore, a TBK1 mutant (E696K) associated with amyotrophic lateral sclerosis and frontotemporal dementia constitutively accumulates at lysosomes, resulting in elevated Rab7 phosphorylation and increased mTORC1 activation. This data establishes the lysosome as a site of amino acid regulated TBK1 signaling that is crucial for efficient mTORC1 activation. This lysosomal pool of TBK1 has broader implications for lysosome homeostasis, and its dysregulation could contribute to the pathogenesis of ALS-FTD.

Keywords: ALS-FTD; Lysosome; Nutrient Sensing; TBK1; mTORC1

DOI: https://doi.org/10.1038/s44318-024-00180-8

Front Mol Biosci. 2024 ;11 1463093

Editorial: Intracellular trafficking and membrane dynamics in health and disease.

Andrea Conte, Cédric Delevoye, Raffaella De Pace.

Keywords: GPI proteins; endoplasmic reticulium; extracellular vesicle (EV); intracellular trafficking; membrane dynamics; retinitis pigmenstosa

DOI: https://doi.org/10.3389/fmolb.2024.1463093

NPJ Parkinsons Dis. 2024 Aug 06. 10(1): 146

PDCD4 triggers α-synuclein accumulation and motor deficits via co-suppressing TFE3 and TFEB translation in a model of Parkinson's disease.

Baihui Cao, Xiaotong Chen, Yubin Li, Tian Zhou, Nuo Chen, Yaxin Guo, Ming Zhao, Chun Guo, Yongyu Shi, Qun Wang, Xuexiang Du, Lining Zhang, Yan Li.

TFE3 and TFEB, as the master regulators of lysosome biogenesis and autophagy, are well characterized to enhance the synaptic protein α-synuclein degradation in protecting against Parkinson's disease (PD) and their levels are significantly decreased in the brain of PD patients. However, how TFE3 and TFEB are regulated during PD pathogenesis remains largely vague. Herein, we identified that programmed cell death 4 (PDCD4) promoted pathologic α-synuclein accumulation to facilitate PD development via suppressing both TFE3 and TFEB translation. Conversely, PDCD4 deficiency significantly augmented global and nuclear TFE3 and TFEB distributions to alleviate neurodegeneration in a mouse model of PD with overexpressing α-synuclein in the striatum. Mechanistically, like TFEB as we reported before, PDCD4 also suppressed TFE3 translation, rather than influencing its transcription and protein stability, to restrain its nuclear translocation and lysosomal functions, eventually leading to α-synuclein aggregation. We proved that the two MA3 domains of PDCD4 mediated the translational suppression of TFE3 through binding to its 5'-UTR of mRNA in an eIF-4A dependent manner. Based on this, we developed a blood-brain barrier penetrating RVG polypeptide modified small RNA drug against pdcd4 to efficiently prevent α-synuclein neurodegeneration in improving PD symptoms by intraperitoneal injections. Together, we suggest PDCD4 as a PD-risk protein to facilitate α-synuclein neurodegeneration via suppressing TFE3 and TFEB translation and further provide a potential small RNA drug against pdcd4 to treat PD by intraperitoneal injections.

DOI: https://doi.org/10.1038/s41531-024-00760-9

Spectrochim Acta A Mol Biomol Spectrosc. 2024 Jul 31. pii: S1386-1425(24)01084-9. [Epub ahead of print]323 124918

Application of acid-activated near-infrared viscosity fluorescent probe targeting lysosomes in cancer visualization.

Lei Hu, Liping Su, Zhiyu Wang, Jing Yang, Yuqing Wang, Jie Wang, Xiaoxia Gu, Hui Wang.

The higher viscosity and lower pH in lysosomes of cancer cells highlight their potential as biomarkers for cancer. Therefore, the development of acid-activated viscosity fluorescent probes is significant for the early diagnosis and treatment of cancer. Based on this, we have designed and synthesized a near-infrared fluorescent probe based on the 2-(2-hydroxyphenyl)benzothiazole (HBT) group, namely HBTH, to monitor the viscosity changes within lysosomes. It has been demonstrated that HBTH was extremely sensitive to viscosity, with a strong linear relationship between fluorescence intensity and log(viscosity) within the range of (logη) = 0-3.06 (a correlation coefficient of 0.98), proving its capability for quantitative viscosity measurement. In particular, the most obvious fluorescence enhancement of HBTH was only efficiently triggered by the combined effect of low pH and high viscosity. Furthermore, HBTH can rapidly localize to lysosomes by wash-free procedure at a low concentration (100 nM) and achieve high-fidelity imaging within 20 s. It can also monitor the dynamic processes of lysosomes in cells, viscosity changes under drug stimuli, and lysosomal behavior during mitophagy. Importantly, HBTH is capable of identifying tumors in tumor-bearing nude mice through in vivo imaging. These features make HBTH a powerful tool for the early diagnosis and treatment of cancer.

Keywords: Cell imaging; Lysosomes; Near-infrared fluorescent probe; Viscosity

DOI: https://doi.org/10.1016/j.saa.2024.124918