# Galectin-8 drives ERK-dependent mitochondrial fragmentation, perinuclear relocation and mitophagy, with metabolic adaptations for cell proliferation

## TL;DR

Galectin-8 causes changes in mitochondria shape and location, boosts mitophagy, and supports cell growth through metabolic shifts.

## Contribution

Galectin-8's role in ERK-dependent mitochondrial dynamics and metabolic adaptations during cell proliferation is newly revealed.

## Key findings

- Gal-8 induces mitochondrial fragmentation and perinuclear redistribution.
- Gal-8 promotes mitophagy and increases aerobic glycolysis for cell proliferation.
- ERK signaling and DRP1 phosphorylation mediate Gal-8's effects on mitochondria.

## Abstract

Mitochondria adapt to the cell proliferative demands induced by growth factors through dynamic changes in morphology, distribution, and metabolic activity. Galectin-8 (Gal-8), a carbohydrate-binding protein that promotes cell proliferation by transactivating the EGFR-ERK signaling pathway, is overexpressed in several cancers. However, its impact on mitochondrial dynamics during cell proliferation remains unknown. Using MDCK and RPTEC kidney epithelial cells, we demonstrate that Gal-8 induces mitochondrial fragmentation and perinuclear redistribution. Additionally, mitochondria adopt donut-shaped morphologies, and live-cell imaging with two Keima-based reporters demonstrates Gal-8-induced mitophagy. ERK signaling inhibition abrogates all these Gal-8-induced mitochondrial changes and cell proliferation. Studies with established mutant versions of Gal-8 and CHO cells reveal that mitochondrial changes and proliferative response require interactions between the N-terminal carbohydrate recognition domain of Gal-8 and α-2,3-sialylated N-glycans at the cell surface. DRP1, a key regulator of mitochondrial fission, becomes phosphorylated in MDCK cells or overexpressed in RPTEC cells in an ERK-dependent manner, mediating mitochondrial fragmentation and perinuclear redistribution. Bafilomycin A abrogates Gal-8-induced cell proliferation, suggesting that mitophagy serves as an adaptation to cell proliferation demands. Functional analysis under Gal-8 stimulation shows that mitochondria maintain an active electron transport chain, partially uncoupled from ATP synthesis, and an increased membrane potential, indicative of healthy mitochondria. Meanwhile, the cells exhibit increased extracellular acidification rate and lactate production via aerobic glycolysis, a hallmark of an active proliferative state. Our findings integrate mitochondrial dynamics with metabolic adaptations during Gal-8-induced cell proliferation, with potential implications for physiology, disease, and therapeutic strategies.

•Galectin-8 induces mitochondrial fragmentation and perinuclear redistribution.•Galectin-8 enhances mitophagy, specifically in a subset of mitochondria.•Galectin-8 modulates mitochondrial dynamics via carbohydrate recognition-ERK-DRP1.•Galectin-8 increases the extracellular acidification rate and lactate production via aerobic glycolysis.

Galectin-8 induces mitochondrial fragmentation and perinuclear redistribution.

Galectin-8 enhances mitophagy, specifically in a subset of mitochondria.

Galectin-8 modulates mitochondrial dynamics via carbohydrate recognition-ERK-DRP1.

Galectin-8 increases the extracellular acidification rate and lactate production via aerobic glycolysis.