MicroRNAs-103/107 coordinately regulate macropinocytosis and autophagy

Abstract

Macropinocytosis, by which cells ingest large amounts of fluid, and autophagy, the lysosome-based catabolic process, involve vesicular biogenesis (early stage) and turnover (end stage). Much is known about early-stage events; however, our understanding of how the end stages of these processes are governed is incomplete. Here we demonstrate that the microRNA-103/107(miR-103/107) family, which is preferentially expressed in the stem cell–enriched limbal epithelium, coordinately regulates aspects of both these activities. Loss of miR-103/107 causes dysregulation of macropinocytosis with the formation of large vacuoles, primarily through up-regulation of Src, Ras, and Ankfy1. Vacuole accumulation is not a malfunction of early-stage autophagy; rather, miR-103/107 ensure proper end-stage autophagy by regulating diacylglycerol/protein kinase C and cyclin-dependent kinase 5 signaling, which enables dynamin to function in vacuole clearance. Our findings unveil a key biological function for miR-103/107 in coordinately suppressing macropinocytosis and preserving end-stage autophagy, thereby contributing to maintenance of a stem cell–enriched epithelium.

miR‐20a inhibits hypoxia‐induced autophagy by targeting ATG5/FIP200 in colorectal cancer

“…miR‐17/92, cluster one of the best characterized oncogenic miRNA cluster, was suggested relating to the hypoxia‐induced autophagy regulation . In addition, miR‐103/107 cluster also regulates autophagy and promote metastasis of CRC . After confirmation of the upregulation of HIF‐1α by CoCl 2 treatment, we investigated the expression of seven miRNA candidates in LoVo and SW48 cells.…”

“…45 miR-17/92, cluster one of the best characterized oncogenic miRNA cluster, was suggested relating to the hypoxia-induced autophagy regulation. 46,47 In addition, miR-103/ 107 cluster also regulates autophagy 48 and promote metastasis of CRC. 49 Because of the multiple potential targets of miR-20a, we examine a series of autophagy-related protein, as well as AKT/mTOR, in LoVo and SW48 cells.…”

FIH‐1 engages novel binding partners to positively influence epithelial proliferation via p63

“…31 To conduct BioID assay, a cDNA encoding FIH-1-BirA* fusion proteins was inserted into the retroviral expression plasmid LZRS. 32 23 For siRNA transfection, cells were transfected with 10 nM siRNA SMARTpools against FIH1, Plectin1, STAT1, apoptosis-stimulating of P53 protein 2 (ASPP2), GADD45α, and non-target control (GE Dharmacon, Colorado, USA) as previously described.…”

“…23 Sections were incubated with primary antibodies (1:50) overnight at 4°C. 32 Image reconstruction was performed with the Nikon NIS Elements software package. Sections were counterstained with DAPI.…”

“…23 For siRNA transfection, cells were transfected with 10 nM siRNA SMARTpools against FIH1, Plectin1, STAT1, apoptosis-stimulating of P53 protein 2 (ASPP2), GADD45α, and non-target control (GE Dharmacon, Colorado, USA) as previously described. 32…”