bims-lypmec 2024-08-18 papers

Issue of 2024‒08‒18
six papers selected by
Satoru Kobayashi, New York Institute of Technology

Ecotoxicol Environ Saf. 2024 Aug 14. pii: S0147-6513(24)00966-7. [Epub ahead of print]284 116890

Lysosomal iron accumulation and subsequent lysosomes-mitochondria iron transmission mediate PFOS-induced hepatocyte ferroptosis.

Jixun Li, Ruzhen Feng, Wei Yang, Peiyao Liang, Tianming Qiu, Jingyuan Zhang, Xiance Sun, Qiujuan Li, Guang Yang, Xiaofeng Yao.

Perfluorooctane sulfonate (PFOS) is known as a persistent organic pollutant. A significant correlation between PFOS and liver ferroptosis has been unveiled, but the precise mechanism needs to be elucidated. In prior research, we found that PFOS treatment provoked mitochondrial iron overload. In this study, we observed a gradual increase in lysosomal iron in L-O2 cells after exposure to PFOS for 0.5-24 h. In PFOS-exposed L-O2 cells, suppressing autophagy relieved the lysosomal iron overload. Inhibiting transient receptor potential mucolipin 1 (TRPML1), a calcium efflux channel on the lysosomal membrane, led to a further rise in lysosomal iron levels and decreased mitochondrial iron overload during PFOS treatment. Suppressing VDAC1, a subtype of voltage-dependent anion-selective channels (VDACs) on the outer mitochondrial membrane, had no impact on PFOS-triggered mitochondrial iron overload, whereas restraining VDAC2/3 relieved this condition. Although silencing VDAC2 relieved PFOS-induced mitochondrial iron overload, it had no effect on PFOS-triggered lysosomal iron overload. Silencing VDAC3 alleviated PFOS-mediated mitochondrial iron overload and led to an additional increase in lysosomal iron. Therefore, we regarded VDAC3 as the specific VDACs subtype that mediated the lysosomes-mitochondria iron transfer. Additionally, in the presence of PFOS, an enhanced association between TRPML1 and VDAC3 was found in mice liver tissue and L-O2 cells. Our research unveils a novel regulatory mechanism of autophagy on the iron homeostasis and the effect of TRPML1-VDAC3 interaction on lysosomes-mitochondria iron transfer, giving an explanation of PFOS-induced ferroptosis and shedding some light on the role of classic calcium channels in iron transmission.

Keywords: Ferroptosis; Lysosomal iron; Mitochondrial iron; PFOS; Transient receptor potential mucolipin 1; Voltage-dependent anion-selective channel 3

DOI: https://doi.org/10.1016/j.ecoenv.2024.116890

Talanta. 2024 Aug 13. pii: S0039-9140(24)01086-5. [Epub ahead of print]280 126707

Long-term tracking of lysosomal dynamics with highly stable fluorescent probe.

Peng Lei, Chuan Dong, Shaomin Shuang, Minglu Li.

Monitoring lysosomal dynamics in real-time, especially in vivo, poses significant challenges due to the complex and dynamic nature of cellular environments. It is extremely important to construct fluorescent probes with high stability for imaging lysosomes to minimize interference from other cellular components, in order to ensure prolonged imaging. A fluorescent probe (PDB) has been proposed for targeting lysosomes, which was less affected to changes in the cellular microenvironment (such as pH, viscosity and polarity). PDB can be easily prepared by 4'-piperazinoacetophenone and 2-(4-diethylamino)-2-hydroxybenzoyl) benzoicacid, containing a piperazine group for labeling and imaging lysosomes and the high pKa value (∼9.35) allowed PDB to efficiently track lysosomes. The emission wavelength of PDB in aqueous solution was 634 nm (λex = 572 nm, Фf = 0.11). The dynamic process of lysosome induced by starvation and rapamycin was successfully explored by fluorescence imaging. Compared with the commercially available Lyso-Tracker green, the high photostability fluorescent probe can ensure 3D high-fidelity tracking and resist photobleaching. Therefore, PDB, unaffected by the cell microenvironment, successfully achieved long-term tracking of lysosomal movement, even enabling imaging in tumor-bearing mice over 11 days. The strong fluorescence signal, high stability, and long-term tracking capability indicate that PDB has tremendous potential in monitoring biological processes.

Keywords: Fluorescent probe; High photostability; Long-term tracking; Lysosomal dynamics

DOI: https://doi.org/10.1016/j.talanta.2024.126707

Autophagy. 2024 Aug 15.

Optogenetic manipulation of lysosomal physiology and autophagic activity.

Wenping Zeng, Canjun Li, Lili Qu, Chunlei Cang.

Lysosomes are essential degradative organelles and signaling hubs within cells, playing a crucial role in the regulation of macroautophagy/autophagy. Dysfunction of lysosomes and impaired autophagy are closely associated with the development of various neurodegenerative diseases. Enhancing lysosomal activity and boosting autophagy levels holds great promise as effective strategies for treating these diseases. However, there remains a lack of methods to dynamically regulate lysosomal activity and autophagy levels in living cells or animals. In our recent work, we applied optogenetics to manipulate lysosomal physiology and function, developing three lysosome-targeted optogenetic tools: lyso-NpHR3.0, lyso-ArchT, and lyso-ChR2. These new actuators enable light-dependent regulation of key aspects such as lysosomal membrane potential, lumenal pH, hydrolase activity, degradation processes, and Ca2+ dynamics in living cells. Notably, lyso-ChR2 activation induces autophagy via the MTOR pathway while it promotes Aβ clearance through autophagy induction in cellular models of Alzheimer disease. Furthermore, lyso-ChR2 activation reduces Aβ deposition and alleviates Aβ-induced paralysis in Caenorhabditis elegans models of Alzheimer disease. Our lysosomal optogenetic actuators offer a novel method for dynamically regulating lysosomal physiology and autophagic activity in living cells and animals.

Keywords: Alzheimer disease; MTOR; autophagy; lysosome; optogenetics

DOI: https://doi.org/10.1080/15548627.2024.2392464

Nat Commun. 2024 Aug 14. 15(1): 6993

Endocytosed dsRNAs induce lysosomal membrane permeabilization that allows cytosolic dsRNA translocation for Drosophila RNAi responses.

Tsubasa Tanaka, Tamaki Yano, Shingo Usuki, Yoko Seo, Kento Mizuta, Maho Okaguchi, Maki Yamaguchi, Kazuko Hanyu-Nakamura, Noriko Toyama-Sorimachi, Katja Brückner, Akira Nakamura.

RNA interference (RNAi) is a gene-silencing mechanism triggered by the cytosolic entry of double-stranded RNAs (dsRNAs). Many animal cells internalize extracellular dsRNAs via endocytosis for RNAi induction. However, it is not clear how the endocytosed dsRNAs are translocated into the cytosol across the endo/lysosomal membrane. Herein, we show that in Drosophila S2 cells, endocytosed dsRNAs induce lysosomal membrane permeabilization (LMP) that allows cytosolic dsRNA translocation. LMP mediated by dsRNAs requires the lysosomal Cl-/H+ antiporter ClC-b/DmOstm1. In clc-b or dmostm1 knockout S2 cells, extracellular dsRNAs are endocytosed and reach the lysosomes normally but fail to enter the cytosol. Pharmacological induction of LMP restores extracellular dsRNA-directed RNAi in clc-b or dmostm1-knockout cells. Furthermore, clc-b or dmostm1 mutant flies are defective in extracellular dsRNA-directed RNAi and its associated antiviral immunity. Therefore, endocytosed dsRNAs have an intrinsic ability to induce ClC-b/DmOstm1-dependent LMP that allows cytosolic dsRNA translocation for RNAi responses in Drosophila cells.

DOI: https://doi.org/10.1038/s41467-024-51343-4

Front Endocrinol (Lausanne). 2024 ;15 1451100

Update on clinical and experimental management of diabetic cardiomyopathy: addressing current and future therapy.

Peter Galis, Linda Bartosova, Veronika Farkasova, Monika Bartekova, Kristina Ferenczyova, Tomas Rajtik.

Diabetic cardiomyopathy (DCM) is a severe secondary complication of type 2 diabetes mellitus (T2DM) that is diagnosed as a heart disease occurring in the absence of any previous cardiovascular pathology in diabetic patients. Although it is still lacking an exact definition as it combines aspects of both pathologies - T2DM and heart failure, more evidence comes forward that declares DCM as one complex disease that should be treated separately. It is the ambiguous pathological phenotype, symptoms or biomarkers that makes DCM hard to diagnose and screen for its early onset. This re-view provides an updated look on the novel advances in DCM diagnosis and treatment in the experimental and clinical settings. Management of patients with DCM proposes a challenge by itself and we aim to help navigate and advice clinicians with early screening and pharmacotherapy of DCM.

Keywords: diabetes mellitus; diabetic cardiomyopathy; diagnostics; heart failure; pharmacotherapy

DOI: https://doi.org/10.3389/fendo.2024.1451100

Anal Chem. 2024 Aug 14.

Lysosome-Targeted Polarity-Sensitive NIR Fluorescence Probe for Imaging Injured Lung and Liver in Diabetes.

Jinzheng Zhang, Shengyi Gong, Qianhua Li, Shiya Zhang, Guoqiang Feng.

Diabetes is a chronic disease marked by high blood glucose. With the progress of diabetes, complications gradually appear, and various organs may be affected. However, due to the lack of noninvasive in situ detection probes, the diagnosis of organ damage caused by diabetes is significantly delayed, which will cause many complications that cannot be treated in time. Here, we report a BODIPY-based fluorescent probe SNL, which can be used to detect lung and liver damage caused by diabetes. By introducing methylpiperazine and extending the conjugated system, SNL can locate lysosomes and exhibit absorption and emission both in the near-infrared (NIR) region. In addition, SNL is sensitive to polarity and can be used for sensitive detection of lysosomal polarity changes. Unexpectedly, SNL targets and images the lungs and liver of mice. Subsequently, hyperglycemia-stimulated cell models and diabetic mouse models were successfully established, and SNL was utilized to reveal that polarity can be used as a diagnostic signal of diabetic complications. Notably, SNL for the first time confirmed the lung injury and liver injury caused by diabetes using the fluorescent probes method, providing a new approach for the diagnosis of diabetes complications.

DOI: https://doi.org/10.1021/acs.analchem.4c03214