A lineage-specific selective autophagy receptor module mediates P-body turnover.

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Processing bodies (P-bodies) are conserved ribonucleoprotein granules central to RNA metabolism across eukaryotes. Although the mechanisms underlying their assembly are well understood, the pathways governing their selective turnover remain unclear. Here, we identify the conserved decapping proteins Enhancer of mRNA decapping 4 (EDC4) and decapping protein 1 (DCP1) as a selective autophagy receptor pair responsible for P-body turnover in the model plant Marchantia polymorpha. MpEDC4 engages ATG8 via a canonical ATG8-interacting motif, while MpDCP1 contains a previously unrecognized reverse ATG8-interacting motif within its intrinsically disordered region. Mutations disrupting these motifs impair the autophagic degradation of P-bodies, demonstrating a cooperative receptor mechanism. Notably, this autophagic function is lineage-specific, as orthologs in Arabidopsis and humans lack ATG8-binding capacity. Strikingly, the heterologous expression of MpEDC4 in human cells promotes the degradation of α-synuclein, a protein linked to Parkinson's disease etiology. Our findings uncover an evolutionary innovation that links RNA metabolism to selective autophagy and open avenues for the cross-kingdom engineering of targeted protein degradation pathways.

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