The CHARGE syndrome-associated protein FAM172A controls AGO2 nuclear import

Sallis, Séphora; Bérubé-Simard, Félix-Antoine; Grondin, Benoı̂t; Leduc, Elizabeth H.; Azouz, Fatiha; Bélanger, Catherine; Pilon, Nicolas

doi:10.26508/lsa.202302133

Cited by 3 publications

(1 citation statement)

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“…Recent studies revealed competitive binding of TNRC6 to various proteins involved in RNA destabilization, such as TRIM71 and UPF1 [27], therefore, RNAi efficiency also depends on the TNRC6 pool available for AGO binding. Nuclear import of AGO:miRNA complexes was linked with Importin 8 in HeLa cells and more recently to FAM172A in mouse embryonic fibroblasts [17,[28][29]. Nevertheless, the underlying molecular mechanisms of AGOs activity, translocation and subsequent RNAi-mediated gene regulation in the nucleus of cancer cells remains to be fully explored.…”

Section: Introductionmentioning

confidence: 99%

Loss of Lamin A leads to the nuclear translocation of AGO2 and compromised RNA interference

Lobo,

Nowak,

Fernandez

et al. 2023

Preprint

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In mammals, RNA interference (RNAi) is mostly studied as a cytoplasmic event, however, numerous reports convincingly show nuclear localization of the AGO proteins. Nevertheless, the mechanism of nuclear entry remains to be fully elucidated, and the extent of nuclear RNAi further explored. We found that reduced Lamin A levels significantly induced nuclear influx of AGO2 in SHSY5Y neuroblastoma and A375 melanoma cancer cell lines, which normally have no nuclear AGO2. The translocation of AGO2 was accompanied by aggravated cell proliferation and we further found that the loss of Lamin A leads to EGFR and Src kinase activation, which regulates the turnover and stability of cytoplasmic AGO2. Furthermore, Lamin A KO significantly reduced the activity of nuclear RNAi. This was evident by AGO fPAR-CLIP in WT and Lamin A KO cells, where we observed ca 60% less efficiency of RNAi. Mass spectrometry of AGO interactome, from the nuclear fraction, indicated that AGO2 is in complex with FAM120A, a known interactor of AGO2 that reduces the activity of RNAi by competing with AGO2 transcript binding. Therefore, loss of Lamin A starts a signaling cascade that mediates nuclear AGO2 translocation to rapidly inhibit RNAi in order to facilitate cancer proliferation.

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Section: Introductionmentioning

confidence: 99%

Loss of Lamin A leads to the nuclear translocation of AGO2 and compromised RNA interference

Lobo,

Nowak,

Fernandez

et al. 2023

Preprint

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Transcriptomic analysis identifies B-lymphocyte kinase as a therapeutic target for desmoplastic small round cell tumor cancer stem cell-like cells

Magrath,

Flinchum,

Hartono

et al. 2024

Oncogenesis

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Desmoplastic small round cell tumor (DSRCT) is an aggressive pediatric cancer caused by the EWSR1-WT1 fusion oncoprotein. The tumor is refractory to treatment with a 5-year survival rate of only 15–25%, necessitating the development of novel therapeutics, especially those able to target chemoresistant subpopulations. Novel in vitro cancer stem cell-like (CSC-like) culture conditions increase the expression of stemness markers (SOX2, NANOG) and reduce DSRCT cell line susceptibility to chemotherapy while maintaining the ability of DSRCT cells to form xenografts. To gain insights into this chemoresistant model, RNA-seq was performed to elucidate transcriptional alterations between DSRCT cells grown in CSC-like spheres and normal 2-dimensional adherent state. Commonly upregulated and downregulated genes were identified and utilized in pathway analysis revealing upregulation of pathways related to chromatin assembly and disassembly and downregulation of pathways including cell junction assembly and extracellular matrix organization. Alterations in chromatin assembly suggest a role for epigenetics in the DSRCT CSC-like state, which was further investigated with ATAC-seq, identifying over 10,000 differentially accessible peaks, including 4444 sphere accessible peaks and 6,120 adherent accessible peaks. Accessible regions were associated with higher gene expression, including increased accessibility of the CSC marker SOX2 in CSC-like culture conditions. These analyses were further utilized to identify potential CSC therapeutic targets, leading to the identification of B-lymphocyte kinase (BLK) as a CSC-enriched, EWSR1-WT1-regulated, druggable target. BLK inhibition and knockdown reduced CSC-like properties, including abrogation of tumorsphere formation and stemness marker expression. Importantly, BLK knockdown reduced DSRCT CSC-like cell chemoresistance, making its inhibition a promising target for future combination therapy.

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Loss of Lamin A leads to the nuclear translocation of AGO2 and compromised RNA interference

Lobo,

Nowak,

Fernandez

et al. 2024

Nucleic Acids Research

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In mammals, RNA interference (RNAi) was historically studied as a cytoplasmic event; however, in the last decade, a growing number of reports convincingly show the nuclear localization of the Argonaute (AGO) proteins. Nevertheless, the extent of nuclear RNAi and its implication in biological mechanisms remain to be elucidated. We found that reduced Lamin A levels significantly induce nuclear influx of AGO2 in SHSY5Y neuroblastoma and A375 melanoma cancer cell lines, which normally have no nuclear AGO2. Lamin A KO manifested a more pronounced effect in SHSY5Y cells compared to A375 cells, evident by changes in cell morphology, increased cell proliferation, and oncogenic miRNA expression. Moreover, AGO fPAR-CLIP in Lamin A KO SHSY5Y cells revealed significantly reduced RNAi activity. Further exploration of the nuclear AGO interactome by mass spectrometry identified FAM120A, an RNA-binding protein and known interactor of AGO2. Subsequent FAM120A fPAR-CLIP, revealed that FAM120A co-binds AGO targets and that this competition reduces the RNAi activity. Therefore, loss of Lamin A triggers nuclear AGO2 translocation, FAM120A mediated RNAi impairment, and upregulation of oncogenic miRNAs, facilitating cancer cell proliferation.

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The CHARGE syndrome-associated protein FAM172A controls AGO2 nuclear import

Cited by 3 publications

References 58 publications

Loss of Lamin A leads to the nuclear translocation of AGO2 and compromised RNA interference

Loss of Lamin A leads to the nuclear translocation of AGO2 and compromised RNA interference

Transcriptomic analysis identifies B-lymphocyte kinase as a therapeutic target for desmoplastic small round cell tumor cancer stem cell-like cells

Loss of Lamin A leads to the nuclear translocation of AGO2 and compromised RNA interference

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