# Distinct roles of clustered MicroRNAs miR-286 and miR-6 in JNK activation critical to apoptosis-induced proliferation in Drosophila

## TL;DR

This study reveals how two microRNAs, miR-286 and miR-6, regulate JNK signaling during apoptosis-induced proliferation in fruit flies.

## Contribution

The paper identifies distinct roles for miR-286 and miR-6 in coordinating JNK activation and amplification during apoptosis-induced proliferation.

## Key findings

- miR-6 promotes initial JNK activation, while miR-286 inhibits its amplification during apoptosis-induced proliferation.
- miR-286 targets Calx, a sodium/calcium exchanger, and its loss enhances JNK amplification and apoptosis-induced proliferation.
- The study reveals a microRNA-based regulatory mechanism coordinating JNK signaling during apoptosis-induced proliferation.

## Abstract

Apoptosis-induced proliferation (AiP) is an evolutionarily conserved process implicated in tissue regeneration and tumorigenesis. Studies in Drosophila have identified activation of the stress response molecule c-Jun N-terminal kinase (JNK) as a critical step in mediating AiP. Interestingly, JNK activation can be further amplified to drive tissue overgrowth during this process. However, the mechanisms that coordinate the initial activation of JNK and its subsequent amplification remain poorly understood. In this study, we identified distinct functions for two members of the microRNA cluster miR-309/3/286/4/5/6 − 1/6 − 2/6 − 3, specifically miR-286 and miR-6, in regulating JNK signaling during AiP. We found that miR-6 promoted the initial activation of JNK, whereas miR-286 inhibited its amplification. During AiP, the expression of miR-286 was reduced, and we identified Calx, a gene encoding a sodium/calcium exchanger involved in intracellular calcium homeostasis, as a direct target of miR-286. Loss of miR-286 led to increased Calx expression and enhanced JNK amplification. Genetically, these promoted AiP through calcium signaling. Together, our findings revealed a microRNA-based regulatory mechanism that coordinates different stages of JNK activation during AiP.

The online version contains supplementary material available at 10.1007/s00018-025-05880-w.