HYL1-CLEAVAGE SUBTILASE 1 (HCS1) suppresses miRNA biogenesis in response to light-to-dark transition.
Proc Natl Acad Sci U S A 2022;
119:2116757119. [PMID:
35121664 PMCID:
PMC8833217 DOI:
10.1073/pnas.2116757119]
[Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2021] [Indexed: 01/02/2023] Open
Abstract
HYPONASTIC LEAVES 1 (HYL1)-CLEAVAGE SUBTILASE 1 (HCS1) is a novel negative regulator of microRNA (miRNA) biogenesis that degrades HYL1 in the cytoplasm. Furthermore, cytoplasm CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) E3 ligase inhibit HCS1-mediated HYL1 degradation. The COP1-HYL1-HCS1 network may integrate two essential cellular pathways: the miRNA-biogenetic pathway and light signaling pathway. Our finding suggests a regulatory pathway in the miRNA-biogenetic system.
The core plant microprocessor consists of DICER-LIKE 1 (DCL1), SERRATE (SE), and HYPONASTIC LEAVES 1 (HYL1) and plays a pivotal role in microRNA (miRNA) biogenesis. However, the proteolytic regulation of each component remains elusive. Here, we show that HYL1-CLEAVAGE SUBTILASE 1 (HCS1) is a cytoplasmic protease for HYL1-destabilization. HCS1-excessiveness reduces HYL1 that disrupts miRNA biogenesis, while HCS1-deficiency accumulates HYL1. Consistently, we identified the HYL1K154A mutant that is insensitive to the proteolytic activity of HCS1, confirming the importance of HCS1 in HYL1 proteostasis. Moreover, HCS1-activity is regulated by light/dark transition. Under light, cytoplasmic CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) E3 ligase suppresses HCS1-activity. COP1 sterically inhibits HCS1 by obstructing HYL1 access into the catalytic sites of HCS1. In contrast, darkness unshackles HCS1-activity for HYL1-destabilization due to nuclear COP1 relocation. Overall, the COP1-HYL1-HCS1 network may integrate two essential cellular pathways: the miRNA-biogenetic pathway and light signaling pathway.
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