Dataset Information

Distinct interactomes of ADAR1 nuclear and cytoplasmic protein isoforms and their responses to Interferon induction

ABSTRACT: The RNA editing enzyme ADAR1, is essential for correct functioning of innate immune responses. The ADAR1p110 isoform is mainly nuclear and ADAR1p150, which is interferon inducible, is predominately cytoplasmic. Using three different approaches, co-IP with endogenous ADAR1, and Strep-tag co-IP and BioID with individual ADAR1 isoforms, a comprehensive interactome was generated during both homeostasis and the IFN response. Both known and novel interactors and editing regulators were identified. Nuclear proteins were detected as stable interactors with both ADAR1 isoforms. In contrast, BioID identified distinct protein networks for each ADAR1 isoform, with nuclear components observed with ADAR1p110 and components of cytoplasmic cellular condensates with ADAR1p150. RNase A digestion distinguished between distal and proximal interactors, as did a dsRNA-binding mutant of ADAR1 which demonstrated the importance of dsRNA binding for ADAR1 interactions. IFN treatment did not affect the core ADAR1 interactomes but resulted in novel interactions, the majority of which are proximal interactions retained after RNase A treatment. Short treatment with HMW poly(I:C) during the IFN response resulted in dsRNA-binding-dependent changes in the proximal protein network of ADAR1p110 and association of the ADAR1p150 proximal protein network with some components of antiviral stress granules.

INSTRUMENT(S): timsTOF Pro

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): A-549 Cell

SUBMITTER: Dragana Vukic

LAB HEAD: Prof. Mary Anne O´Connell, Ph.D.

PROVIDER: PXD056080 | Pride | 2024-12-08

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	21257_1_WT1_IgG_neg_S3-A1_1.d.zip	Other
	21259_2_WT1_IgG_pos_S3-B1_1.d.zip	Other
	21261_3_WT1_A1_neg_S3-C1_1.d.zip	Other
	21263_4_WT1_A1_pos_S3-D1_1.d.zip	Other
	21265_5_WT2_IgG_neg_S3-E1_1.d.zip	Other

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Project description:Sensing of double-stranded RNA (dsRNA) is an important component of innate immunity. Proteins like PKR and MDA5 recognize dsRNA and activate various pathways to fight viral infection. In addition to viral dsRNA, many endogenous RNAs containing double-stranded regions can be misrecognized as immunogenic. The RNA editing enzyme ADAR1, specifically its p150 isoform, has been shown to suppress activation of PKR and MDA5 through its A-to-I editing activity. While the cytoplasmic ADAR1-p150 isoform has been well established within this role, the functions of the nuclear ADAR1-p110 isoform are less understood. To address this knowledge gap, we utilized proximity labeling by APEX2 to identify putative ADAR1-p110 interacting proteins. We identified 110 proteins across three breast cancer cell lines that either interact with p110 or are within close proximity. Many of these proteins have known roles in RNA metabolism. Nine of the identified proteins belong to the DEAD or DEAH box families of RNA helicases, including DHX9. DHX9 is overexpressed in breast cancer, with expression closely correlated with that of p110. By co-immunoprecipitation we confirmed that p110 interacts with DHX9. Knockdown of DHX9 in several triple-negative breast cancer cell lines caused cell death and activation of the dsRNA sensor PKR. In two cell lines that are refractory to knockdown of ADAR1, the combined knockdown of DHX9 and ADAR1 caused a substantial increase in PKR activity, where knockdown of either alone had no effect. Knockdown of DHX9 and ADAR1 caused activation of the type I IFN pathway, RNase L and NF-KB signaling. Activation of these proteins and pathways was not seen with individual knockdown of ADAR1 or DHX9. Activation of PKR following combined knockdown of ADAR1 and DHX9 could be rescued by expression of p110, p150, DHX9, and catalytically inactive DHX9. Additionally PKR activation could be rescued by the dsRBM of DHX9, revealing an important role for dsRBMs in suppressing PKR activation. Together these results reveal an important role for DHX9 in suppressing dsRNA sensing by multiple pathways.

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Distinct interactomes of ADAR1 nuclear and cytoplasmic protein isoforms and their responses to Interferon induction

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