Mitochondrial dysfunction is a central hallmark of aging, contributing to impaired energy production, reduced mitophagy, and tissue decline across species [1]. A key driver of this dysfunction is the imbalance of mitochondrial dynamics: with age, mitochondria lose their ability to undergo fission, resulting in enlarged and dysfunctional organelles 1, 2, 3, 4. Remarkably, restoring the activity of the fission GTPase Drp1 in midlife is sufficient to reverse age-associated defects and extend lifespan in Drosophila [3]. These findings highlight that the failure of fission is not merely a consequence of aging but a causal mechanism contributing to cellular and organismal decline [4]. Yet, the upstream signals that trigger the age-dependent loss of fission capacity remain poorly defined.

Drp1 is a cytosolic GTPase that is recruited to the outer mitochondrial membrane (OMM), where it oligomerizes to drive membrane constriction and division 5, 6. This recruitment is regulated by post-translational modifications and by adaptor proteins such as Mff, Fis1, and MiD49/51 7, 8, 9. While these protein-based mechanisms have been extensively characterized, the contribution of the lipid environment to Drp1 function is less understood. Cardiolipin and phosphatidic acid have been implicated in remodeling mitochondrial membranes 10, 11, 12, but whether other lipid classes, particularly those altered by aging, directly regulate Drp1 recruitment remains unresolved.

Plasmalogens are vinyl-ether phospholipids enriched in polyunsaturated fatty acids that promote membrane curvature [13], modulate fluidity [14], and buffer oxidative stress [15]. Their biosynthesis requires sequential peroxisomal and ER steps, with the terminal desaturation catalyzed by plasmanylethanolamine desaturase (PEDS), encoded by Kua in Drosophila and TMEM189 in mammals. Loss of Kua/TMEM189 markedly reduces plasmalogen levels 16, 17. Plasmalogen has recently emerged as a novel regulator of mitochondrial dynamics [18], respirasome assembly [19], oxidative stress and ferroptosis 20, 21, 22, neuronal protection 23, 24, 25, and lifespan 26, 27, 28. Importantly, plasmalogen abundance declines progressively with age in humans, mice, and rats 29, 30, 31, 32. This age-related depletion destabilizes membranes, increases oxidative vulnerability, and has been associated with mitochondrial defects 13, 15, 18, 33. Despite these observations, whether plasmalogen decline directly contributes to impaired mitochondrial fission during aging is unknown.

Drosophila melanogaster provides a genetically tractable platform to dissect lipid regulation of organelle aging. Its oenocytes, peroxisome-rich and hepatocyte-like cells 34, 35, are highly specialized for lipid metabolism and are uniquely sensitive to age-related declines in peroxisomal import and mitochondrial maintenance 36, 37. These properties make them a powerful platform to probe how lipid composition governs mitochondrial dynamics during aging. Although peroxisome-derived lipids can influence mitochondrial morphology in mammalian adipocytes during thermogenesis [18], whether plasmalogen biosynthesis itself directly regulates mitochondrial fission in vivo, particularly in context of aging, remains unknown.

Mitochondrial dynamics have been studied extensively in cultured cells, yet direct methods to visualize these processes in adult tissues in Drosophila have been lacking, limiting in vivo insights into how aging influences fission and fusion. To address this gap, we developed a live-cell imaging pipeline for adult oenocytes and applied it to examine mitochondrial dynamics during aging. In parallel, we used confocal microscopy, and biochemical fractionation to test whether plasmalogen biosynthesis regulates Drp1 recruitment and mitochondrial fission. By integrating these approaches, we identify plasmalogens as critical lipid cofactors for mitochondrial remodeling and demonstrate that aging itself suppresses stress-induced fission, thereby establishing a conserved lipid–protein checkpoint that governs mitochondrial dynamics during aging.