A synaptic mitochondrion–ribbon–vesicle complex organizes photoreceptor neurotransmission
Year: 2026
Type: article
Abstract: Photoreceptor synapses rely on mitochondria, synaptic ribbons, and vesicles, yet how these elements integrate into functional units remains unclear. Here we show, using focused ion beam-scanning electron microscopy (FIB-SEM) and electrophysiology, that they form synaptic mitochondrion–ribbon–vesicle complexes (sMRVcs) with fundamentally different architectures in rods and cones. Rod spherules exhibit a strict 1:1 pairing of a single megamitochondrion with one ribbon, sustaining continuous glutamate release in darkness, whereas cone pedicles contain multiple distributed sMRVcs. Disrupting the mitochondrial anchor protein syntaphilin shifts this ratio to 2:1 in rods, with additional mitochondria recruited near the ribbon, and enhances synaptic transmission. In a retinal degeneration model, the sMRVc progressively disassembles before functional decline, with fragmented mitochondria, detached ribbons, and dispersed vesicles. We also identify non-ribbon release sites selectively targeting horizontal cells. These findings establish the sMRVc as a conserved structural–metabolic module whose subtype-specific organization reflects distinct visual demands and whose integrity is essential for synaptic health. Researchers find photoreceptor synapses contain mitochondrion–ribbon–vesicle complexes: rods have a 1:1 megamitochondrion–ribbon pair; cones have distributed units. Disrupting mitochondrial anchoring shifts rods to 2:1 and boosts signaling, while degeneration breaks the complex apart.
Source: Nature Communications
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $6,990
OpenAlex ID: W7223475441
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