Molecular mechanisms of membrane traffic at the endosomes and late golgi

The National Institute of General Medical Sciences awarded the Regents of the University of Michigan $1,770,576 on July 1, 2026, under the Biomedical Research and Research Training program (CFDA 93.859) to investigate molecular mechanisms of membrane traffic at endosomes and the trans-Golgi network, focusing on clathrin adaptor protein complex-1 (AP1)-mediated traffic and the role of HEATR5 proteins in AP1 function and coat regulation.

The research employs in vitro and in vivo methods, including synthetic systems for ectopic coat formation, structure-function analyses, partially purified systems, and advanced imaging technologies to elucidate HEATR5 membrane recruitment, regulation, and AP1 modulation. The work addresses gaps in understanding membrane traffic that controls protein localization and function across plasma and organellar membranes; mutations impairing endosomal and trans-Golgi traffic proteins cause inherited human diseases affecting skin, intestine, brain, eyes, and ears, and pathways are exploited by pathogens.

The recipient is the University of Michigan, performing the work at Ann Arbor, Michigan. The period of performance extends from July 1, 2026, through June 30, 2030. The obligated amount is $1,770,576. This is assistance provided as a Project Grant, an R01 award mechanism supporting investigator-initiated basic research.

Abstract

Membrane traffic controls the localization and, thereby, function of many biomedically important proteins located at the plasma membrane and within internal membrane-bounded organelles. This traffic allows cells to adapt to environmental changes, cellular signals, or developmental stimuli. Mutations that impair the proteins involved in traffic at the endosomes and late golgi, also known as the TGN, result in various inherited human diseases affecting systems like the skin, intestine, brain, eyes, and ears. Additionally, these pathways are vital for numerous pathogens. Our overarching aim is to thoroughly understand TGN traffic, leveraging this understanding to enhance human health. Despite being crucial, many aspects of TGN traffic remain poorly characterized, leaving several key aspects of the process unclear. Our current aim is to investigate traffic centered on the clathrin adaptor protein complex-1 (AP1)-mediated traffic. Recent findings from our research group and others have highlighted the importance of HEATR5 proteins in AP1 function and coat regulation, though the mechanism remains unknown. We will explore unresolved questions about HEATR5 proteins, such as their membrane recruitment, regulation, and role in AP1 modulation. To achieve this, we'LL employ both in vitro and in vivo methods, including a synthetic in vivo system for ectopic coat formation, structure-function analyses, partially purified systems, and advanced imaging technologies. These investigations will bridge gaps in our knowledge of TGN traffic and offer mechanistic insights essential for guiding the diagnosis of rare diseases and laying the groundwork for developing therapies targeting this critical cellular process.