Chan, C. E. | bioRxiv Science

bioRxiv2026

A miniature bioluminescent platform for imaging structured RNAs

A broader understanding of RNA biology requires methods for visualizing transcript dynamics in native environments. Common imaging approaches rely on fluorescent probes that require excitation light and often depend on large aptamer arrays, limiting sensitivity and compatibility with many non-coding RNAs, particularly highly structured folds. To address these challenges, we developed a miniaturized bioluminescent platform for RNA imaging. This system employs a compact RNA tag that assembles luciferase fragments upon binding of monomeric RNA-binding proteins (RNA lanterns). Systematic optimization of the RNA component yielded a structured 24-nucleotide tag, representing greater than 3-fold reduction in size relative to the original C-11-B RNA tag, placing it among the smallest RNA imaging tags reported to date. The optimized tag enabled RNA-dependent bioluminescence detection in live cells, notably as a small, single insert within highly structured non-coding RNAs, including the MALAT1 ENE domain and a small HDV-like ribozyme. Collectively, this work establishes a miniaturized bioluminescent platform for imaging a broad range of RNA targets in living systems.

molecular biology↗

bioRxiv2025

Airway Secretory Cells Contain Both a Perinuclear Golgi Ribbon and Dispersed Golgi Satellites

RationaleFinely tuned production and secretion of the polymeric mucins MUC5AC and MUCB are required for lung health, but knowledge of many details between their translation and their packaging into secretory granules is lacking. ObjectivesTo analyze the structure and function of the Golgi apparatus, a key site of mucin glycosylation, folding, polymerization and packaging, in airway epithelial secretory cells. MethodsLung tissue was obtained from mice stimulated or not with IL-13 to upregulate mucin production, and from normal human lungs. Golgi elements in mouse and human tissue were imaged by high-resolution immunofluorescence microscopy and electron microscopy. Tissue from mice with deletion of both polymeric mucins was also examined. Measurements and Main ResultsBy immunofluorescence microscopy, both mouse and human airway secretory cells contained [~]100 dispersed puncta labeled by markers of medial and trans Golgi cisternae and the trans-Golgi network (TGN), but only a few perinuclear puncta were labeled by markers of cis-Golgi cisternae. By electron microscopy, secretory cells contained both a perinuclear Golgi ribbon and numerous dispersed Golgi stacks, termed satellites. In mucous metaplastic cells, satellites were concentrated among immature mucin granules. Increasing mucin production by cytokine stimulation did not increase the number of TGN puncta, nor did preventing polymeric mucin production by gene deletion reduce TGN puncta. ConclusionsMucin-producing airway secretory cells express an unusual Golgi structure consisting of a conventional perinuclear Golgi ribbon as well as dispersed satellites. While the Golgi satellites are likely an adaptation for mucin production and packaging, their presence is specified developmentally, independent of mucin production.

cell biology↗