Sialoglycoconjugate Profiling of Human Choroid, Retinal Pigment Epithelium, and Macular Degeneration Related Lesions

Navratil, E. M.; Wenzel, P. A.; Flamme-Wiese, M. J.; Miller, J. E. B.; Wiley, L. A.; Stone, E. M.; Tucker, B. A.; Mullins, R. F.

doi:10.1101/2025.04.23.650306

bioRxiv · 10.1101/2025.04.23.650306

Sialoglycoconjugate Profiling of Human Choroid, Retinal Pigment Epithelium, and Macular Degeneration Related Lesions

Navratil, E. M.·Wenzel, P. A.·Flamme-Wiese, M. J.·Miller, J. E. B.·Wiley, L. A.·Stone, E. M.·Tucker, B. A.·Mullins, R. F.

View original source ↗Export metadata ↓

Abstract

Age-related macular degeneration is a leading cause of central vision loss in the elderly. Early hallmarks of the disease include basal laminar deposit and choriocapillaris degeneration. The location and composition of sialoglycoconjugates in healthy and diseased choroid and disease-related lesions have not been thoroughly examined. This study utilized lectins to examine sialoglycoconjugates in human tissue, specifically Sambucus nigra/Elderberry Bark Lectin (EBL) and Maackia amurensis lectin II (MAL-II), to examine -2,6 and -2,3 sialic acids, respectively. EBL and MAL-II both label the choroid and basal laminar deposit, with slightly different patterns. Whereas MAL-II predominantly labels the choriocapillaris endothelium, EBL also labels Bruchs membrane and extracellular domains surrounding the vasculature (intercapillary pillars). EBL labeling overlaps with the distribution of complement factor H to a greater extent than MAL-II. After treatment with neuraminidase to remove terminal sialic acids, a battery of lectins was applied to sections of choroids. Lectins that recognize {beta}-galactose, N-acetyllactosamine, galactose ({beta}-1,3) N-acetylgalactosamine, and - or {beta}-N-acetylgalactosamine showed increased reactivity, including increased labeling of glycans in basal laminar deposits. This study provides insight into the location and partial identities of sialoglycoconjugates in the human choroid, with possible implications for the pathogenesis of macular degeneration.

Explore related subjects

cell biology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Navratil, E. M., Wenzel, P. A., Flamme-Wiese, M. J., Miller, J. E. B., Wiley, L. A., Stone, E. M., Tucker, B. A., Mullins, R. F.. 2025-04-23. Sialoglycoconjugate Profiling of Human Choroid, Retinal Pigment Epithelium, and Macular Degeneration Related Lesions. https://doi.org/10.1101/2025.04.23.650306

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Sequence context and partner availability specify divergent cell fates from a single transcription factor

Transcription factors drive the gene regulatory networks that control developmental transitions, yet which of their many targets a cell uses remains unresolved. Expressing Cebp, Cebp{beta} or Cebp{delta} identically, alone or with Oct4, Sox2, Klf4 and cMyc, gave four outcomes: adipocyte from fibroblasts and neural stem cells, trophectoderm from embryonic stem cells, and myeloid from B cells. Raising Cebp levels changed how many sites it reached, not which sequence it read: clustered motifs maintained somatic enhancers, while spillover onto low-copy sites created de novo enhancers carrying composites of Cebp and cell-type-restricted partners. In fibroblasts, Cebp also redistributed Oct4, Sox2 and Klf4 from early targets, blocking iPSC formation. Supplying the predicted partners rewrote the output: Spi1 redirected Cebp into parallel adipogenic and myeloid programs, via a transient PpargCD45 state using separate enhancers for each; TFAP2C abolished adipogenic conversion. Motif density and partner composites therefore assemble a factor's instructive output in the receiving cell.

cell biology↗

bioRxiv2026

Tracking the conformational dynamics of single molecules in live cells; GTPase cycling in Cdc42 gradients and microclusters

The Rho family of GTPases play a critical role in many cellular processes by acting as molecular switches relying on conformational changes to transition between active and inactive states. The spatial distribution and kinetics of these conformational changes are complex and vary across the cell. We describe here biosensors based on environment-responsive fluorescent dyes, capable of reporting the conformational changes of individual GTPase molecules as they traffic within living cells (SPARC Cdc42 and SPARC Rac1, 'Single Particle Activation Reporter Constructs'). We use SPARC Cdc42 to determine the rates of different steps in GTPase regulation, activation/inactivation and membrane insertion, that together generate localized gradients of Cdc42 activity driving cell motility. The biosensors also revealed heterogeneously distributed clusters of Cdc42, the mechanisms of their activation, and potential roles in polarized motility.

cell biology↗

bioRxiv2026

High-content screening identifies FDA-approved activators of mitophagy

Mitochondrial diseases are highly heterogeneous disorders caused by defects in oxidative phosphorylation, for which only limited therapeutic options are available. The elimination of dysfunctional mitochondria via mitophagy activation is an attractive strategy to treat several mitochondrial diseases, irrespective of the underlying genetic defect. To identify pharmacological activators of this pathway, we performed a high-content screening of 1,971 FDA-approved compounds using cellular reporters of TFEB nuclear translocation and mitophagy. This screening identified 294 compounds that promoted TFEB translocation, nine of which increased the number of mitolysosomes without compromising cell viability or damaging mitochondria. Among the selected compounds, Meptazinol and Ponatinib emerged as the top-ranked mitophagy inducers in fibroblasts from patients with complex I and IV deficiency, respectively, and were prioritised for further characterisation. However, they did not rescue the bioenergetic defect, suggesting that the stimulation of mitophagy per se is not sufficient to ameliorate the OXPHOS defect in mitochondrial diseases. Overall, our findings establish a scalable platform for the identification of pharmacological activators of TFEB and identify candidate compounds for therapeutic modulation of mitophagy.

cell biology↗