bims-lycede 2025-06-22 papers

Autophagy. 2025 Jun 18. 1-20

Lysosomal membrane permeabilization enhances the anticancer effects of POLR1 (RNA polymerase I) transcription inhibitors.

Lucille Ferret, Jonathan G Pol, Allan Sauvat, Gautier Stoll, Karla Alvarez-Valadez, Alexandra Muller, Julie Le Naour, Felix Peyre, Gerasimos Anagnostopoulos, Isabelle Martins, Maria Chiara Maiuri, Harald Wodrich, Lionel Guittat, Jean-Louis Mergny, Guido Kroemer, Mojgan Djavaheri-Mergny.

Lysosomes contribute to the development of drug resistance through various mechanisms that include drug sequestration and the activation of adaptive stress pathways. While inhibitors of DNA-to-RNA transcription exhibit potent anticancer effects, the role of lysosomes in modulating responses to such transcription inhibitors remains largely unexplored. This study investigates this aspect in the context of two potent POLR1 (RNA polymerase I) transcription inhibitors, CX-3543 (quarfloxin) and CX-5461 (pidnarulex). Unexpectedly, CX-3543 was found to accumulate within lysosomes, leading to lysosomal membrane permeabilization (LMP) and the subsequent activation of cellular stress adaptation pathways, including those regulated by the transcription factor TFEB and autophagy. Disrupting TFEB or autophagy increased cell sensitivity to CX-3543, highlighting the cytoprotective role of these processes in counteracting CX-3543-induced cell death. Moreover, targeting lysosomal membranes with chloroquine derivatives or blue light exposure induced substantial LMP, releasing compound CX-3543 from lysosomes. This effect enhanced both the inhibition of DNA-to-RNA transcription and CX-3543-induced cell death. Similar effects were observed when chloroquine derivatives were combined with CX-5461. Additionally, combining CX-3543 with the chloroquine derivative DC661 more effectively reduced the fibrosarcoma growth in immunocompetent mice than either agent alone. Altogether, our results reveal an unanticipated lysosome-related mechanism that contributes to cancer cell resistance to POLR1 inhibitors and propose a strategy to overcome this resistance.Abbreviations: ATG7: autophagy related 7; ATG13: autophagy related 13; Baf A1: bafilomycin A1; CTSB: cathepsin B; DKO: double knockout; G4: Guanine quadruplex; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LAMP2: lysosomal associated membrane protein 2; LGALS3: galectin 3; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MTORC1: mechanistic target of rapamycin kinase complex 1; NCL: nucleolin; POLR1: RNA polymerase I; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TFE3: transcription factor E3; ULK1: unc-51 like autophagy activating kinase 1.

Keywords: Autophagy; TFEB; cancer; cell death; guanine quadruplex ligands; resistance to therapy

DOI: https://doi.org/10.1080/15548627.2025.2497614

ACS Chem Biol. 2025 Jun 16.

Biphasic Cellular Response Triggered by Tetrandrine-Mediated Dysfunction and Lysophagic Clearance of Lysosomes.

Zhe Yang, Tomoki Takahashi, Ayase Hoshino, Tatsuya Yamamoto, Hideyuki Shigemori, Yusaku Miyamae.

Lysosomes play an important role in the degradation of cellular components and are correlated with various other physiological phenomena. Lysophagy is a cellular quality control system that maintains homeostasis by removing damaged lysosomes through autophagy. The involvement of lysosomal dysfunction in the pathogenesis of certain illnesses (e.g., neurodegeneration) highlights the potential of small molecules that regulate lysophagy as drug candidates. Here, we found that tetrandrine, a bis-benzylisoquinoline alkaloid, induces lysophagy, leading to the clearance of damaged lysosomes in mammalian cells. To visualize the target organelles of tetrandrine, we synthesized a chimeric compound in which tetrandrine was connected to boron-dipyrromethene via a polyethylene glycol linker. Flow cytometry analysis confirmed the cellular uptake of the synthesized probe. An organelle-staining assay showed that the fluorescent signal of the probe was specifically colocalized with lysosomes. Tetrandrine transiently increased the lysosomal pH level, which returned to normal at 24 h post treatment. Consistently, the level of mCherry-tagged galectin-3, a marker protein for lysophagy, transiently increased and then diminished under treatment with tetrandrine. Tetrandrine also induced dephosphorylation of transcription factor EB, a regulator of lysosomal biogenesis, promoting its translocation from the cytosol to the nucleus. These results suggest that tetrandrine induces a biphasic cellular response, first disrupting lysosomal function before facilitating cellular lysosomal homeostasis through lysophagy and lysosomal biogenesis. This dual effect distinguishes tetrandrine from existing lysosomal modulators.

DOI: https://doi.org/10.1021/acschembio.5c00220

Trends Cell Biol. 2025 Jun 16. pii: S0962-8924(25)00115-1. [Epub ahead of print]

Time matters: the dynamics of plasma membrane repair.

Nikita Raj, Volker Gerke.

The plasma membrane (PM) of eukaryotic cells is constantly exposed to many challenges that can cause wounds that necessitate rapid and efficient repair mechanisms to ensure cell survival. PM wound repair not only encompasses the immediate resealing of the membrane barrier, which involves exocytosis of internal vesicles to deliver membrane, but also subsequent processes that are essential to restore cellular homeostasis. These include restoration of membrane and cortical cytoskeleton structures, as well as replenishment of intracellular organelles consumed during resealing. Recent evidence suggests that the different steps in PM repair, resealing, restructuring, and restoration, are spatiotemporally correlated and regulated by membrane tension. Recent advances in understanding the different phases of PM repair are reviewed and a time-dependent classification of repair mechanisms is proposed.

Keywords: calcium; endocytosis; exocytosis; membrane wound

DOI: https://doi.org/10.1016/j.tcb.2025.05.005

Int J Oral Sci. 2025 Jun 16. 17(1): 50

Isolation methods of exosomes derived from dental stem cells.

Paras Ahmad, Nathan Estrin, Nima Farshidfar, Yufeng Zhang, Richard J Miron.

Mesenchymal stem cells are highly regarded for their potential in tissue repair and regenerative medicine due to their multipotency and self-renewal abilities. Recently, mesenchymal stem cells have been redefined as "medical signaling cells," with their primary biological effects mediated through exosome secretion. These exosomes, which contain lipids, proteins, RNA, and metabolites, are crucial in regulating various biological processes and enhancing regenerative therapies. Exosomes replicate the effects of their parent cells while offering benefits such as reduced side effects, low immunogenicity, excellent biocompatibility, and high drug-loading capacity. Dental stem cells, including those from apical papilla, gingiva, dental pulp, and other sources, are key contributors to exosome-mediated regenerative effects, such as tumor cell apoptosis, neuroprotection, angiogenesis, osteogenesis, and immune modulation. Despite their promise, clinical application of exosomes is limited by challenges in isolation techniques. Current methods face issues of complexity, inefficiency, and insufficient purity, hindering detailed analysis. Recent advancements, such as micro-electromechanical systems, alternating current electroosmosis, and serum-free three-dimensional cell cultures, have improved exosome isolation efficacy. This review synthesizes nearly 200 studies on dental stem cell-derived exosomes, highlighting their potential in treating a wide range of conditions, including periodontal diseases, cancer, neurodegenerative disorders, diabetes, and more. Optimized isolation methods offer a path forward for overcoming current limitations and advancing the clinical use of exosome-based therapies.

DOI: https://doi.org/10.1038/s41368-025-00370-y

Cell Commun Signal. 2025 Jun 19. 23(1): 296

Lysosomal targeting of liposomes with acidic pH and Cathepsin B induces protein aggregate clearance.

Minsol Jeon, Da-Eun Kim, So Young Choi, Seoyoung Kim, Seongchan Kim, Hyojin Lee, Hyunkyung Kim.

The autophagy-lysosomal pathway is a cellular degradation mechanism that regulates protein quality by eliminating aggregates and maintaining normal protein function. It has been reported that aging itself reduces lysosomal proteolytic activity in age-related neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. Reduction in lysosomal function may underlie the accumulation of protein aggregates such as amyloid beta (Aβ), tau, and α-synuclein. Some of these protein aggregates may cause additional lysosomal dysfunction and create a vicious cycle leading to a gradual increase in protein aggregation. In this study, liposome-based lysosomal pH-modulating particles (LPPs), containing a liquid solution to adjust lysosomal pH, have been developed to restore lysosomal function. The results demonstrate that acidic LPPs effectively restore lysosomal function by recovering lysosomal pH and facilitating the removal of protein aggregates. These findings demonstrated that acidic LPPs could effectively recover the abnormal lysosomal function via restoration of lysosomal pH and enhance the clearance of protein aggregates. Furthermore, the simultaneous introduction of Cathepsin B (CTSB) proteins and acidic LPP revealed a synergistic effect, promoting lysosomal pH recovery and enhancing aggregates removal. These findings suggest a novel strategy for improving lysosomal clearance activity in proteinopathies.

Keywords: Aggregate clearance; Autophagy; Cathepsin; Lysosome; Proteinopathy

DOI: https://doi.org/10.1186/s12964-025-02310-z