Pardo-Pinon, M. | Search bioRxiv

bioRxiv2026

Cargo-Adaptor Cooperation Programs Retromer Coat Architecture

Retromer drives endosomal cargo retrieval in combination with sorting nexin (SNX) adaptors, but how adaptor-cargo combinations specify coat architecture remains unclear. We identify sorting nexin 12 (SNX12) as the retromer adaptor required for human papillomavirus 16 (HPV16) infection and show that the viral L2 capsid protein tail directly engages SNX12-retromer complexes to trigger membrane tubulation. The crystal structure reveals a conserved cargo-recognition mode, whereas cryo-electron tomography of reconstituted assemblies shows retromer arches organized into two lattice configurations stabilized by membrane-proximal interfaces. These lattices assemble as multi-start helices and accommodate curvature through hinge-like motions between arches. These findings establish cargo and adaptor identity as co-determinants of retromer coat architecture, revealing retromer as a programmable system capable of generating route-specific transport carriers.

cell biology↗

bioRxiv2025

AAV2 Bypasses Direct Endosomal Escape by Using AAVR to Access the Trans-Golgi Network en Route to the Nucleus.

Vectors based on the adeno-associated virus are widely used as delivery methods in gene therapy applications, yet understanding of the mechanisms governing its intracellular trafficking remains incomplete. Traditional models suggest that AAV escapes from endosomes via membrane disruption, but direct evidence for this process are lacking. Here, we show that AAVR, the essential AAV cell entry receptor, functions as a bona fide retromer cargo. Using in vitro reconstitution assays, we demonstrate that AAVRs cytosolic tail is sufficient to engage the SNX3-retromer complex and drive membrane tubulation, a hallmark of retrograde trafficking. In AAVR-knockout HuH-7 cells, AAV2 particles are internalized but fail to reach the trans-Golgi network (TGN) and support transgene expression. Galectin-8 recruitment assays reveal no evidence of endosomal membrane rupture during productive transduction, distinguishing AAV2 from lytic vectors such as lipid nanoparticles. Moreover, VP1u-deficient and PLA2-mutant AAV2 capsids accumulate at the TGN, indicating that VP1u is dispensable for early trafficking but required for post-TGN progression toward productive transduction. These findings challenge the prevailing model of direct endosomal escape and position AAV transduction as a vesicle-guided, receptor-mediated process.

cell biology↗