bims-lycede 2024-07-21 papers

Issue of 2024‒07‒21
three papers selected by
Sofía Peralta, Universidad Nacional de Cuyo

Exp Cell Res. 2024 Jul 17. pii: S0014-4827(24)00260-X. [Epub ahead of print] 114169

Sulfiredoxin-1 promotes the growth of hepatocellular carcinoma by inhibiting TFEB-mediated autophagy and lysosome biogenesis.

Qianwen Rao, Mengzhou Guo, Jialei Sun, Biwei Yang, Xin Cao, Jinglin Xia.

Advanced hepatocellular carcinoma (HCC) patients have poor prognosis. As an endogenous antioxidant enzyme involved in a variety of bioprocesses, sulfiredoxin-1 (SRXN1) plays an irreplaceable role in promoting the development of tumors. However, the role and working mechanism of SRXN1 in HCC remain unclear. In this study, we confirmed that SRXN1 promoted the cell proliferation of HCC at genetic and pharmacological level, respectively. Transcriptome sequencing analysis revealed SRXN1 knockdown had a significant effect on the expression of lysosome biogenesis related genes. Further experiments validated that lysosome biogenesis and autophagic flux were enhanced after SRXN1 inhibition and reduced as SRXN1 overexpression. Mechanism study revealed that ROS accumulation induced TFEB nuclear translocation, followed by increased autophagy. Following this rationale, the combination of SRXN1 inhibitor and sorafenib demonstrated noticeable synergistic antitumor effect through the boost of ROS both in vivo and in vitro. Taken together, SRXN1 could be a potential therapeutic target for HCC therapy.

Keywords: HCC; ROS; SRXN1; TFEB; autophagy

DOI: https://doi.org/10.1016/j.yexcr.2024.114169

Zool Res. 2024 07 18. pii: 2095-8137(2024)04-0937-14. [Epub ahead of print]45(4): 937-950

TAX1BP1 and FIP200 orchestrate non-canonical autophagy of p62 aggregates for mouse neural stem cell maintenance.

Yi-Fu Zhu, Rong-Hua Yu, Shuai Zhou, Pei-Pei Tang, Rui Zhang, Yu-Xin Wu, Ran Xu, Jia-Ming Wei, Ying-Ying Wang, Jia-Li Zhang, Meng-Ke Li, Xiao-Jing Shi, Yu-Wei Zhang, Guang-Zhi Liu, Rick F Thorne, Xu Dong Zhang, Mian Wu, Song Chen.

Autophagy plays a pivotal role in diverse biological processes, including the maintenance and differentiation of neural stem cells (NSCs). Interestingly, while complete deletion of Fip200 severely impairs NSC maintenance and differentiation, inhibiting canonical autophagy via deletion of core genes, such as Atg5, Atg16l1, and Atg7, or blockade of canonical interactions between FIP200 and ATG13 (designated as FIP200-4A mutant or FIP200 KI) does not produce comparable detrimental effects. This highlights the likely critical involvement of the non-canonical functions of FIP200, the mechanisms of which have remained elusive. Here, utilizing genetic mouse models, we demonstrated that FIP200 mediates non-canonical autophagic degradation of p62/sequestome1, primarily via TAX1BP1 in NSCs. Conditional deletion of Tax1bp1 in fip200 hGFAP conditional knock-in (cKI) mice led to NSC deficiency, resembling the fip200 hGFAP conditional knockout (cKO) mouse phenotype. Notably, reintroducing wild-type TAX1BP1 not only restored the maintenance of NSCs derived from tax1bp1-knockout fip200 hGFAP cKI mice but also led to a marked reduction in p62 aggregate accumulation. Conversely, a TAX1BP1 mutant incapable of binding to FIP200 or NBR1/p62 failed to achieve this restoration. Furthermore, conditional deletion of Tax1bp1 in fip200 hGFAP cKO mice exacerbated NSC deficiency and p62 aggregate accumulation compared to fip200 hGFAP cKO mice. Collectively, these findings illustrate the essential role of the FIP200-TAX1BP1 axis in mediating the non-canonical autophagic degradation of p62 aggregates towards NSC maintenance and function, presenting novel therapeutic targets for neurodegenerative diseases.

Keywords: Aggregates; FIP200; Neural stem cell; Non-canonical autophagy; TAX1BP1; p62

DOI: https://doi.org/10.24272/j.issn.2095-8137.2024.021

Bio Protoc. 2024 Jul 05. 14(13): e5025

Quantification of Autophagosomes in Human Fibroblasts Using Cyto-ID® Staining and Cytation Imaging.

Barbara Hochecker, Katja C Matt, Alica L Meßmer, Melanie M Scherer, Jörg Bergemann.

As an essential process for the maintenance of cellular homeostasis and function, autophagy is responsible for the lysosome-mediated degradation of damaged proteins and organelles; therefore, dysregulation of autophagy in humans can lead to a variety of diseases. The link between impaired autophagy and disease highlights the need to investigate possible interventions to address dysregulations. One possible intervention is hyperthermia, which is described in this protocol. To investigate these interventions, a method for absolute quantification of autophagosomal compartments is required that allows comparison of autophagosomal activity under different conditions. Existing methods such as western blotting and immunohistochemistry for analysing the location and relative abundance of intracellular proteins associated with autophagy, or transmission electron microscopy (TEM), which are either very time-consuming, expensive, or both, are less suitable for this purpose. The method described in this protocol allows the absolute quantification of autophagosomes per cell in human fibroblasts using the CYTO-ID® Autophagy Detection Kit after heat therapy compared to a control. The Cyto-ID® assay is based on the use of a specific dye that selectively stains autophagic compartments, combined with an additional Hoechst 33342 dye for nuclear staining. The subsequent recognition of these stained compartments by the Cytation Imager enables the software to determine the number of autophagosomes per nucleus in living cells. Additionally, this absolute quantification uses an image-based method, and the protocol is easy to use and not time-consuming. Furthermore, the method is not only suitable for heat therapy but can also be adapted to any other desired therapy or substance. Key features • Absolute quantification of autophagic compartments in living cells. • Optimised protocol for the determination of autophagy in primary human skin fibroblasts. • Allows the testing of active substances and treatments concerning autophagy. • Imaging-based method for the determination of autophagy.

Keywords: Absolute quantification; Autophagy; Hyperthermia; Imaging-based method; Primary human skin fibroblasts

DOI: https://doi.org/10.21769/BioProtoc.5025