Biology subjects

Elazar, Z.

Publications and source records attributed to Elazar, Z..

4 recordsLinked to original sources

bioRxiv2025

Aberrant inheritance of extrachromosomal DNA amplifications promotes cancer evolution

Gene amplification in the form of extrachromosomal DNA (ecDNA) is a frequent driver in multiple cancer types. As ecDNA lack centromeres, their mitotic segregation does not follow traditional inheritance principles. However, the mechanisms that govern ecDNA fate following mitosis remain unclear. We found that ecDNA undergo numerical and structural optimization under increased selective pressure, with mitotic chromosomal tethering, or detachment, dictating ecDNA fate. When tethered, ecDNA aggregates promote uneven distribution into the newly formed daughter cells, thereby driving inter-cellular numerical heterogeneity and rapid increase of amplification under selective pressure. Mitotically detached ecDNA frequently encapsulate within micronuclei of variable size and content that appear to be highly fragile. Strikingly, ecDNA enclosed in very small micronuclei, which we term nanonuclei, are being actively degraded through autophagy. Together with ongoing structural rearrangements, nanonuclear ecDNA degradation promotes their structural evolution, which facilitates cancer cell adaptation. Our work highlights ecDNA aggregation, micronucleation, and degradation, as pivotal events in directing cancer genome evolution trajectories.

cancer biology↗

bioRxiv2025

TECPR2 maintains mitochondrial homeostasis in neurodegeneration

HSAN9 is a rare progressive neurodegenerative disease in children linked to bi-allelic loss-of-function mutations in the TECPR2 gene. TECPR2 is a multi-domain protein harboring N-terminal WD repeats and C-terminal TECPR repeats, followed by a functional LIR motif that serves in autolysosomal targeting. Here, we show that the lack of TECPR2 leads to impairment of mitophagy that can be recovered by the expression of its C-terminal domain. Accordingly, we uncover severe mitochondrial dysfunction and accumulation of mitochondrial content in primary fibroblasts derived from an HSAN9 patient, and in embryonic fibroblasts and dorsal root ganglia derived from an HSAN9 mouse model. Strikingly, these mitochondrial defects are mediated by a mitochondrial stress through activation of the integrated stress response (ISR), whereas mitochondrial function is recovered by pharmaceutical or genetic suppression of ISR. Our findings provide a new link between mitophagy and ISR in mitochondrial homeostasis during neurodegeneration.

cell biology↗

bioRxiv2024

A new cellular platform for studying autophagy

Atg8 proteins play a crucial role in autophagy. There is a single Atg8 isoform in yeast, while mammals have up to seven homologs categorized into LC3s and GABARAPs. The GABARAP subfamily consists of GABARAP, GABARAPL1, and GABARAPL2/GATE16, implicated in various stages along the pathway. However, the intricacies among GABARAP proteins are complex and require a more precise delineation. Here, we introduce a new cellular platform to study autophagy using CRISPR/Cas9-mediated tagging of endogenous genes of the GABARAP subfamily with different fluorescent proteins. This platform allows robust examination of autophagy by flow cytometry of cell populations and monitoring of GABARAP homologs at single-cell resolution using fluorescence microscopy. Strikingly, the simultaneous labeling of the different endogenous GABARAPs allows the identification and isolation of autophagosomes differentially marked by these proteins. Using this system, we found that the different GABARAPs are associated with different autophagosomes. We argue that this new cellular platform will be crucial in studying the unique roles of individual GABARAP proteins in autophagy and other putative cellular processes.

cell biology↗

bioRxiv2023

Rim aperture of autophagic membranesbalances cargo inclusion with vesicle maturation

Autophagy eliminates cytoplasmic material by engulfment in membranous vesicles targeted for lysosome degradation. Nonselective autophagy coordinates the sequestration of bulk cargo with the growth of the isolation membrane (IM) in a yet-unknown manner. Here we show the yeast IM expands while maintaining a rim sufficiently wide for sequestration of large cargo but tight enough to mature in due time. An obligate complex of Atg24/Snx4 with Atg20 or Snx41 assembles locally at the rim in a spatially-extended manner that specifically depends on autophagic PI(3)P. This assembly stabilizes the open rim to promote autophagic sequestration of large cargo in correlation with vesicle inflation. Moreover, constriction of the rim by the PI(3)P-dependent Atg2-Atg18 complex and clearance of PI(3)P by Ymr1 antagonize the rim opening to promote autophagic maturation and consumption of small cargo. Tight regulation of membrane rim aperture by PI(3)P thus couples the mechanism and physiology of nonselective autophagy.

cell biology↗