Dataset Information

CSN6, a subunit of the COP9 signalosome, is involved in early response to iron deficiency in Oryza sativa.

ABSTRACT: The COP9 signalosome (CSN) plays an important role in proteasome-mediated degradation by regulating CUL1 rubylation of the SCF ligase and is involved in many crucial biological processes. Here, we demonstrate a link between IDEF1 accumulation and the decline in COP9 derubylation activity in response to iron deficiency (-Fe) in rice (Oryza sativa). CSN6 expression is rapidly down-regulated during Fe depletion, contributing to reduced CSN activity, as judged by CSN5 and CUL1 expression, indicating CSN6 is involved in the early stage response of -Fe. In contrast to CSN6, the IDEF1 protein and expression of several iron uptake/utilisation-related genes are increased in response to -Fe. Thus, we constructed CSN6 transgenic sense and antisense lines and found that experimental depletion of CSN6 results in accumulation of the IDEF1 protein and up-regulation of several iron uptake/utilisation-related genes. Furthermore, IDEF1 can be decorated with K48-linked polyubiquitin and degraded via the 26S proteasome. Accumulated IDEF1 in antisense lines led to increased chlorophyll and Fe content in seedlings during -Fe. Collectively, the cellular CSN6 level is decreased during early stages of -Fe to ensure the rapid accumulation of IDEF1, which in turn up-regulates several iron uptake/utilisation-related genes to help overcome -Fe stress in rice.

SUBMITTER: Tan S

PROVIDER: S-EPMC4853791 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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CSN6, a subunit of the COP9 signalosome, is involved in early response to iron deficiency in Oryza sativa.

Tan Song S Liu Fang F Pan Xiao-Xi XX Zang Yue-Peng YP Jin Fei F Zu Wei-Xi WX Qi Xiao-Ting XT Xiao Wei W Yin Li-Ping LP

Scientific reports 20160503

The COP9 signalosome (CSN) plays an important role in proteasome-mediated degradation by regulating CUL1 rubylation of the SCF ligase and is involved in many crucial biological processes. Here, we demonstrate a link between IDEF1 accumulation and the decline in COP9 derubylation activity in response to iron deficiency (-Fe) in rice (Oryza sativa). CSN6 expression is rapidly down-regulated during Fe depletion, contributing to reduced CSN activity, as judged by CSN5 and CUL1 expression, indicating ...[more]

PMID: 27137867

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Project description:The COP9 signalosome (CSN) is a highly conserved protein complex in eukaryotes, affecting various development and signaling processes. To date, the biological functions of the COP9 signalosome and its subunits have not been determined in Magnaporthe oryzae. In this study, we characterized the CSN in M. oryzae (which we named MoCsn6) and analyzed its biological functions. MoCsn6 is involved in fungal development, autophagy, and plant pathogenicity. Compared with the wild-type strain 70-15, ΔMocsn6 mutants showed a significantly reduced growth rate, sporulation rate, and germ tube germination rate. Pathogenicity assays showed that the ΔMocsn6 mutants did not cause or significantly reduced the number of disease spots on isolated barley leaves. After the MoCSN6 gene was complemented into the ΔMocsn6 mutant, vegetative growth, sporulation, and pathogenicity were restored. The Osm1 and Pmk1 phosphorylation pathways were also disrupted in the ΔMocsn6 mutants. Furthermore, we found that MoCsn6 participates in the autophagy pathway by interacting with the autophagy core protein MoAtg6 and regulating its ubiquitination level. Deletion of MoCSN6 resulted in rapid lipidation of MoAtg8 and degradation of the autophagic marker protein green fluorescent protein-tagged MoAtg8 under nutrient and starvation conditions, suggesting that MoCsn6 negatively regulates autophagic activity. Taken together, our results demonstrate that MoCsn6 plays a crucial role in regulating fungal development, pathogenicity, and autophagy in M. oryzae. IMPORTANCE Magnaporthe oryzae, a filamentous fungus, is the cause of many cereal diseases. Autophagy is involved in fungal development and pathogenicity. The COP9 signalosome (CSN) has been extensively studied in ubiquitin pathways, but its regulation of autophagy has rarely been reported in plant-pathogenic fungi. Investigations on the relationship between CSN and autophagy will deepen our understanding of the pathogenic mechanism of M. oryzae and provide new insights into the development of new drug targets to control fungal diseases. In this study, the important function of Csn6 in the autophagy regulation pathway and its impact on the pathogenicity of M. oryzae were determined. We showed that Csn6 manages autophagy by interacting with the autophagy core protein Atg6 and regulating its ubiquitination level. Furthermore, future investigations that explore the function of CSN will deepen our understanding of autophagy mechanisms in rice blast fungus.

Dataset Information

CSN6, a subunit of the COP9 signalosome, is involved in early response to iron deficiency in Oryza sativa.

Publications

CSN6, a subunit of the COP9 signalosome, is involved in early response to iron deficiency in Oryza sativa.

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