P40phox, a third cytosolic component of the activation complex of the NADPH oxidase to contain src homology 3 domains.
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ABSTRACT:
SUBMITTER: Wientjes FB
PROVIDER: S-EPMC1137734 | biostudies-other | 1993 Dec
REPOSITORIES: biostudies-other
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Project description:Small nucleolar RNAs (snoRNAs) guide nucleotide modifications of cellular RNAs in the nucleus. We have previously shown that box C/D snoRNAs from the Rpl13a locus are unexpected mediators of physiologic oxidative stress, independent of their predicted ribosomal RNA modifications. Here, we demonstrate that oxidative stress induced by doxorubicin causes rapid cytoplasmic accumulation of the Rpl13a snoRNAs through a mechanism that requires superoxide and a nuclear splice variant of NADPH oxidase. RNA-sequencing analysis reveals that box C/D snoRNAs as a class are present in the cytoplasm, where their levels are dynamically regulated by NADPH oxidase. These findings suggest that snoRNAs may orchestrate the response to environmental stress through molecular interactions outside of the nucleus.
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Project description:Cytosolic components of the NADPH oxidase interact with the actin cytoskeleton. These interactions are thought to be important for the activation of this enzyme system but they are poorly characterised at the molecular level. Here we have explored the interaction between the actin cytoskeleton and p40(phox), one of the cytosolic components of NADPH oxidase. Full length p40(phox) expressed in COS cells co-localised with F-actin in a peripheral lamellar compartment. The co-localisation was lost after deletion of the Phox homology (PX) domain and the PX domain in isolation (p40PX) showed the same F-actin co-localisation as the full length protein. PX domains are known lipid-binding modules however, a mutant p40PX which did not bind lipids still co-localised with F-actin suggesting that lipid-independent interactions underlie the localisation. Affinity chromatography identified actin as a binding partner for p40PX in neutrophil extracts. Pure actin interacted with both p40(phox) and with p40PX suggesting it is a direct interaction. Disruption of the actin cytoskeleton with cytochalasin D resulted in actin rearrangement and concomitantly the localisation of full length p40(phox) proteins and that of p40PX changed. Thus p40PX is a dual F-actin/lipid-binding module and F-actin interactions with the PX domain dictate at least in part the intracellular localisation of the cytosolic p40(phox) subunit of the NADPH oxidase.
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