Lysosomal biogenesis and function is critical for necrotic cell death in Caenorhabditis elegans

Abstract

Necrotic cell death is defined by distinctive morphological characteristics that are displayed by dying cells (Walker, N.I., B.V. Harmon, G.C. Gobe, and J.F. Kerr. 1988. Methods Achiev. Exp. Pathol. 13:18–54). The cellular events that transpire during necrosis to generate these necrotic traits are poorly understood. Recent studies in the nematode Caenorhabditis elegans show that cytoplasmic acidification develops during necrosis and is required for cell death (Syntichaki, P., C. Samara, and N. Tavernarakis. 2005. Curr. Biol. 15:1249–1254). However, the origin of cytoplasmic acidification remains elusive. We show that the alkalization of endosomal and lysosomal compartments ameliorates necrotic cell death triggered by diverse stimuli. In addition, mutations in genes that result in altered lysosomal biogenesis and function markedly affect neuronal necrosis. We used a genetically encoded fluorescent marker to follow lysosome fate during neurodegeneration in vivo. Strikingly, we found that lysosomes fuse and localize exclusively around a swollen nucleus. In the advanced stages of cell death, the nucleus condenses and migrates toward the periphery of the cell, whereas green fluorescent protein–labeled lysosomal membranes fade, indicating lysosomal rupture. Our findings demonstrate a prominent role for lysosomes in cellular destruction during necrotic cell death, which is likely conserved in metazoans.

Autophagy is required for necrotic cell death in Caenorhabditis elegans

“…Construction of p mec-17 GFP and p mec-17 LMP-1HGFP has been described previously. 31 For RNAi experiments, we constructed plasmids that direct the synthesis of dsRNAs corresponding to the genes of interest (see below), in Escherichia coli bacteria, which were then fed to animals, according to a previously described methodology. 39 To augment RNAi, animals were reared for two generations on dsRNA-producing E. coli bacteria before examination.…”

“…Indeed, calpain activity has been implicated in mediating lysosomal rupture during necrosis both in C. elegans and in mammals. 27,31,32 …”

Decreased Insulin-Receptor Signaling Promotes the Autophagic Degradation of β-Amyloid Peptide inC. elegans

“…Aspartyl proteases (ASPs), lysosome-associated membrane protein-1 (LMP-1) and vacuolar H + -ATPases (VHAs) have been implicated in lysosomal-mediated neurodegeneration in C. elegans. [51][52][53] The C. elegans ASP-1, ASP-2, ASP-5 and ASP-6 proteins are homologous to the lysosomal protease …”

“…7,8 Furthermore, LMP-1 has been demonstrated to localize to lysosomes in C. elegans neurons. 53 Vacuolar H + -ATPases mediate the acidification of organelles and their function is required for autophagic degradation. 52,56 Again, we utilized feeding RNAi to inhibit ASP, LMP and VHA-15 function in order to examine the role of lysosomal proteases, lysosomal-membrane proteins and vacuolar acidification during Aβ-toxicity.…”

New frontiers in promoting tumour cell death: targeting apoptosis, necroptosis and autophagy

“…In many cases, necrosis is also accompanied by lysosomal membrane disintegration and release of lysosomal hydrolases, which help catalyse the breakdown of the cell (Artal-Sanz et al, 2006;Boya and Kroemer, 2008). Unlike apoptotic cells, the nuclei of necrotic cells remain largely intact (Vandenabeele et al, 2010).…”