Biology subjects

Gai, W.

Publications and source records attributed to Gai, W..

4 recordsLinked to original sources

bioRxiv2026

Conformation governs cellular behaviors of LRRK2 Parkinson's disease variants

Gain-of-function of leucine-rich repeat kinase 2 (LRRK2) is a common cause of Parkinson's disease (PD). In its autoinhibited state, the leucine-rich repeats of LRRK2 block the kinase active site, preventing substrate phosphorylation. Displacing the repeats ('unlatching') primes LRRK2 for activity. Preferential unlatching causes increased substrate phosphorylation of the PD allele LRRK2[R1441H], but not LRRK2[G2019S]. Here, we define a large class of PD-associated 'unlatching' mutations based on their effect on LRRK2 conformation. Unlatching mutants show increased localization to membranes, the site of LRRK2's Rab substrates. Unlatching mutants are also characterized by decreased LRRK2 S935 phosphorylation, which we define as a biomarker of conformation. This framework resolves the mechanism of variants such as I2020T, which structural studies could not predict. Overall, we establish unlatching as a unifying mechanism for most PD-linked variants and describe measurable readouts for identifying LRRK2-driven disease.

cell biology↗

bioRxiv2026

The structural basis for LRRK2's activation and autoinhibition

Mutations in Leucine-Rich Repeat Kinase 2 (LRRK2) are the second most common cause of autosomal-dominant Parkinsons disease (PD), and increased LRRK2 kinase activity is also observed in idiopathic PD, making LRRK2 a major actionable therapeutic target. LRRK2 is a 286-kDa multidomain enzyme containing a Ras-like GTPase (ROC) and a kinase domain. Using cryo-EM, biochemical reconstitution, and cell-based assays, we show that the ROC GTPase governs switching between autoinhibited and active states: GTP binding promotes activation, whereas GDP binding enforces autoinhibition. Two common PD-linked mutations, G2019S and R1441C/G/H, activate LRRK2 through distinct structural mechanisms, revealing genotype-specific routes to dysregulation. These findings provide a unified framework for understanding LRRK2 regulation with broad therapeutic implications. Stabilizing the GDP-bound state may inhibit LRRK2 by maintaining autoinhibition, whereas promoting the GTP-bound state could be advantageous in specific cellular contexts, such as the lung, where increased LRRK2 kinase activity may play protective or regulatory roles.

neuroscience↗

bioRxiv2024

GTP hydrolysis triggers membrane remodeling by AMPH-1

Membrane-enclosed transport carriers return biological molecules from the recycling endosome to the plasma membrane using a mechanism that is not well understood. In C. elegans, the formation of carriers from the recycling endosome requires the amphiphysin protein, AMPH-1. Recently, we found that purified AMPH-1 is sufficient for tubulation and vesiculation of liposomes in a mechanism that is regulated by guanine nucleotides. Here we propose a model linking GTP binding and hydrolysis to the membrane binding and tubulation required for transport carrier formation. We find that GTP binding stabilizes interactions between AMPH-1 and the membrane through amphipathic, N-terminal alpha helices, which are found at the tips of the arc-shaped, homodimeric structure. By contrast, in the post-hydrolysis, GDP-bound state, these helices are repositioned to interact with the N-terminal helices of other homodimers, to form an oligomeric AMPH-1 lattice that tubulates the membrane, in preparation for carrier formation by membrane fission.

biochemistry↗

bioRxiv2020

Applications of genetic-epigenetic tissue mapping for plasma DNA in prenatal testing, transplantation and oncology

We developed Genetic-Epigenetic Tissue Mapping (GETMap) to determine the tissue composition of plasma DNA carrying genetic variants not present in the constitutional genome through comparing their methylation profiles with relevant tissues. We validated this approach by showing that, in pregnant women, circulating DNA carrying fetal-specific alleles was entirely placenta-derived. In lung-transplant recipients, we showed that, at 72 hours after transplantation, the lung contributed only a median of 17% to the plasma DNA carrying donor-specific alleles and hematopoietic cells contributed a median of 78%. In hepatocellular cancer patients, the liver was identified as the predominant source of plasma DNA carrying tumor-specific mutations. In a pregnant woman with lymphoma, plasma DNA molecules carrying cancer mutations and fetal-specific alleles were accurately shown to be derived from the lymphocytes and placenta, respectively. Analysis of tissue origin for plasma DNA carrying genetic variants is potentially useful for noninvasive prenatal testing, transplantation monitoring and cancer screening.

physiology↗