bims-lycede 2024-07-28 papers

Issue of 2024‒07‒28
four papers selected by
Sofía Peralta, Universidad Nacional de Cuyo

EMBO J. 2024 Jul 23.

Connexin43 promotes exocytosis of damaged lysosomes through actin remodelling.

Neuza Domingues, Steve Catarino, Beatriz Cristóvão, Lisa Rodrigues, Filomena A Carvalho, Maria João Sarmento, Mónica Zuzarte, Jani Almeida, Teresa Ribeiro-Rodrigues, Ânia Correia-Rodrigues, Fábio Fernandes, Paulo Rodrigues-Santos, Trond Aasen, Nuno C Santos, Viktor I Korolchuk, Teresa Gonçalves, Ira Milosevic, Nuno Raimundo, Henrique Girão.

A robust and efficient cellular response to lysosomal membrane damage prevents leakage from the lysosome lumen into the cytoplasm. This response is understood to happen through either lysosomal membrane repair or lysophagy. Here we report exocytosis as a third response mechanism to lysosomal damage, which is further potentiated when membrane repair or lysosomal degradation mechanisms are impaired. We show that Connexin43 (Cx43), a protein canonically associated with gap junctions, is recruited from the plasma membrane to damaged lysosomes, promoting their secretion and accelerating cell recovery. The effects of Cx43 on lysosome exocytosis are mediated by a reorganization of the actin cytoskeleton that increases plasma membrane fluidity and decreases cell stiffness. Furthermore, we demonstrate that Cx43 interacts with the actin nucleator Arp2, the activity of which was shown to be necessary for Cx43-mediated actin rearrangement and lysosomal exocytosis following damage. These results define a novel mechanism of lysosomal quality control whereby Cx43-mediated actin remodelling potentiates the secretion of damaged lysosomes.

Keywords: Actin-remodelling; Arp2; Connexin43; Exocytosis; Lysosomal Damage

DOI: https://doi.org/10.1038/s44318-024-00177-3

Ageing Res Rev. 2024 Jul 20. pii: S1568-1637(24)00246-0. [Epub ahead of print] 102428

Autophagy in aging-related diseases and cancer: Principles, regulatory mechanisms and therapeutic potential.

Na Wu, Wenhui Zheng, Yundong Zhou, Yu Tian, Min Tang, Xiaoqiang Feng, Milad Ashrafizadeh, Yuzhuo Wang, Xiaojia Niu, Murtaza Tambuwala, Lingzhi Wang, Vinay Tergaonkar, Gautam Sethi, Daniel Klionsky, Li Huang, Ming Gu.

Macroautophagy/autophagy is primarily accountable for the degradation of damaged organelles and toxic macromolecules in the cells. Regarding the essential function of autophagy for preserving cellular homeostasis, changes in, or dysfunction of, autophagy flux can lead to disease development. In the current paper, the complicated function of autophagy in aging-associated pathologies and cancer is evaluated, highlighting the underlying molecular mechanisms that can affect longevity and disease pathogenesis. As a natural biological process, a reduction in autophagy is observed with aging, resulting in an accumulation of cell damage and the development of different diseases, including neurological disorders, cardiovascular diseases, and cancer. The MTOR, AMPK, and ATG proteins demonstrate changes during aging, and they are promising therapeutic targets. Insulin/IGF1, TOR, PKA, AKT/PKB, caloric restriction and mitochondrial respiration are vital for lifespan regulation and can modulate or have an interaction with autophagy. The specific types of autophagy, such as mitophagy that degrades mitochondria, can regulate aging by affecting these organelles and eliminating those mitochondria with genomic mutations. Autophagy and its specific types contribute to the regulation of carcinogenesis and they are able to dually enhance or decrease cancer progression. Cancer hallmarks, including proliferation, metastasis, therapy resistance and immune reactions, are tightly regulated by autophagy, supporting the conclusion that autophagy is a promising target in cancer therapy.

Keywords: Aging; autophagy; cancer therapy; cell death; longevity

DOI: https://doi.org/10.1016/j.arr.2024.102428

Methods Mol Biol. 2024 Jul 25.

Assessment of Non-canonical Functions of the Autophagy Proteins in LC3-Associated Phagocytosis and LC3-Associated Endocytosis.

Luigi Mari, Emilio Boada-Romero, Zhenrui Li, Joelle Magné, Douglas R Green.

The identification and characterization of noncanonical functions within the autophagy pathway have unveiled intricate cellular processes, including LC3-associated phagocytosis (LAP) and LC3-associated endocytosis (LANDO). These phenomena play pivotal roles in the conjugation of ATG8 with single-membrane phagosomes and endosomes, shedding light on the dynamic interplay between autophagy and cellular homeostasis. Here, we present detailed protocols for both qualitative and quantitative assessment of LAP, including immunofluorescence, flow cytometry, and Western blotting of isolated LAPosomes. Additionally, the protocol for the evaluation of LANDO through immunofluorescent detection of receptor recycling is outlined. The methodologies presented herein serve as a practical guide for researchers seeking to unravel the intricacies of LAP and LANDO. By providing step-by-step instructions, accompanied by insights into potential challenges and optimization strategies, this chapter aims to empower investigators in the exploration of these noncanonical functions of autophagy proteins.

Keywords: ATG8; Autophagy; Flow cytometry; Immunofluorescence; LANDO; LAP; LC3-associated endocytosis; LC3-associated phagocytosis; Phagosome; Receptor recycling; Western blotting

DOI: https://doi.org/10.1007/7651_2024_561

Autophagy. 2024 Jul 20. 1-4

Integrating bioengineering, super-resolution microscopy and mechanobiology in autophagy research: addendum to the guidelines (4th edition).

Andrea Ravasio, Daniel J Klionsky, Cristina Bertocchi.

Recent key technological developments, such as super-resolution microscopy and microfabrication, enabled investigation of biological processes, including macroautophagy/autophagy, with unprecedented spatiotemporal resolution and control over experimental conditions. Such disruptive innovations deepened our capability to provide mechanistic understandings of the autophagic process and its causes. This addendum aims to expand the guidelines on autophagy in three key directions: optical methods enabling visualization of autophagic machinery beyond the diffraction-limited resolution; bioengineering enabling accurate designs and control over experimental conditions; and theoretical advances in mechanobiology connecting autophagy and mechanical processes of the cell. Abbreviation: 3D: three-dimensional; SIM: structured illumination microscopy; STORM: stochastic optical reconstruction microscopy.

Keywords: Bioengineering; interdisciplinarity; mechanoautophagy; microfabrication; microfluidics; super-resolution microscopy

DOI: https://doi.org/10.1080/15548627.2024.2379065