Ngo Jordan Matthew, Williams Justin Krish, Temoche-Diaz Morayma Mercedes, Murugupandiyan Abinayaa, Schekman Randy
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.
Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States.
bioRxiv. 2025 Mar 20:2025.03.20.644464. doi: 10.1101/2025.03.20.644464.
Exosomes are multivesicular body-derived extracellular vesicles that are secreted by metazoan cells. Exosomes have utility as disease biomarkers, and exosome-mediated miRNA secretion has been proposed to facilitate tumor growth and metastasis. Previously, we demonstrated that the Lupus La protein (La) mediates the selective incorporation of miR-122 into metastatic breast cancer-derived exosomes; however, the mechanism by which La itself is sorted into exosomes remains unknown. Using unbiased proximity labeling proteomics, biochemical fractionation, superresolution microscopy and genetic tools, we establish that the selective autophagy receptor p62 sorts La and miR-122 into exosomes. We then performed small RNA sequencing and found that p62 depletion reduces the exosomal secretion of tumor suppressor miRNAs and results in their accumulation within cells. Our data indicate that p62 is a quality control factor that modulates the miRNA composition of exosomes. Cancer cells may exploit p62-dependent exosome cargo sorting to eliminate tumor suppressor miRNAs and thus to promote cell proliferation.
外泌体是后生动物细胞分泌的多泡体来源的细胞外囊泡。外泌体可作为疾病生物标志物，并且有人提出外泌体介导的miRNA分泌有助于肿瘤生长和转移。此前，我们证明狼疮La蛋白（La）介导miR-122选择性地掺入转移性乳腺癌来源的外泌体中；然而，La自身被分选到外泌体中的机制仍然未知。通过使用无偏向性邻近标记蛋白质组学、生化分级分离、超分辨率显微镜和遗传学工具，我们确定选择性自噬受体p62将La和miR-122分选到外泌体中。然后我们进行了小RNA测序，发现p62缺失会减少肿瘤抑制性miRNA的外泌体分泌，并导致它们在细胞内积累。我们的数据表明p62是一种调节外泌体miRNA组成的质量控制因子。癌细胞可能利用p62依赖的外泌体货物分选来消除肿瘤抑制性miRNA，从而促进细胞增殖。
