Biology subjects

Moulton, M. J.

Publications and source records attributed to Moulton, M. J..

6 recordsLinked to original sources

bioRxiv2026

Progressive behavioral and cognitive decline in Drosophila harboring AD-associated APOE4 variants

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, and its incidence is rising rapidly with population aging. Pathologically, AD is characterized by the accumulation of amyloid-beta (Abeta) plaques and hyperphosphorylated Tau neurofibrillary tangles. Human genomic studies have identified numerous risk alleles, with the APOE4 variant representing the strongest and most common genetic risk factor, present in approximately 75 percent of AD patients. However, APOE4 is neither necessary nor sufficient to cause disease, suggesting that additional genetic and environmental factors contribute to AD pathogenesis. Emerging evidence highlights a central role for oxidized lipid metabolism in AD. Disruption of lipid metabolism leads to lipid accumulation, reactive oxygen species (ROS) toxicity, and neurodegeneration, suggesting that oxidative stress may be a critical factor in enhancing AD susceptibility. To systematically investigate APOE function in vivo, we tested humanized Drosophila expressing the human APOE3 or APOE4 variants in place of the Drosophila ortholog Glial Lazarillo (GLaz). The lifespan of APOE3 and APOE4 flies does not differ under standard housing conditions, but the lifespan of APOE4 flies is significantly reduced when exposed to the ROS-promoting drug rotenone, supporting a multi-hit model of disease pathogenesis. APOE4 flies exposed to rotenone exhibit several AD-associated phenotypes, including age-related memory loss and chemosensory deficits, supporting the use of this model to investigate AD pathogenesis. Furthermore, progressive AD-associated phenotypes are also observed in APOE4 flies maintained on an obesogenic diet, suggesting that enhanced disease susceptibility is not specific to rotenone-induced stress but reflects a broader vulnerability to metabolic challenges. Together, these findings establish a scalable model to dissect APOE-dependent mechanisms and identify therapeutic targets in AD.

genetics↗

bioRxiv2025

A reference model for adult human cardiovascular mechanics

A previously developed computational model for cardiovascular mechanics is here calibrated using typical values of 22 clinically observed hemodynamic properties in healthy human subjects. The model includes spatially resolved representations of the four heart chambers. The left ventricle is represented as a truncated thick-walled prolate spheroid, with three modes of deformation (short and long axis contraction and torsion). The other chambers are represented as full or partial thick-walled spherical shells. Wave propagation and reflection in the aorta are represented using a one-dimensional model. The closed-loop system is completed using lumped elements representing vascular resistances, compliances and inertances. The resulting system of coupled ordinary differential equations can be solved computationally in less than 0.1 s per cardiac cycle. In the present study, the values of 19 key input parameters to the model are estimated by minimizing the deviation of model predictions from the 22 observed hemodynamic properties. The resulting calibrated reference model provides a baseline for theoretical studies exploring the relationship between fundamental properties of the cardiovascular system, such as ventricular contractility and stiffness or vascular resistance and compliance, and clinically available measurements such as blood pressures, chamber volumes or valve flow waveforms.

bioengineering↗

bioRxiv2022

Autolysosomal exocytosis of lipids protect neurons from ferroptosis

During oxidative stress neurons release lipids that are internalized by glia. Defects in this coordinated process play an important role in several neurodegenerative diseases. Yet, the mechanisms of lipid release and its consequences on neuronal health are unclear. Here, we demonstrate that lipid-protein particle release by autolysosome exocytosis protects neurons from ferroptosis, a form of cell death driven by lipid peroxidation. We show that during oxidative stress, peroxidated lipids and iron are released from neurons by autolysosomal exocytosis which requires the exocytic machinery; VAMP7 and syntaxin 4. We observe membrane-bound lipid-protein particles by TEM and demonstrate that these particles are released from neurons using cryoEM. Failure to release these lipid-protein particles causes lipid hydroperoxide and iron accumulation and sensitizes neurons to ferroptosis. Our results reveal how neurons protect themselves from peroxidated lipids. Given the number of brain pathologies that involve ferroptosis, defects in this pathway likely play a key role in the pathophysiology of neurodegenerative disease. SUMMARYRelease of lipid-protein particles by autolysosomal exocytosis protects neurons from ferroptosis.

cell biology↗

bioRxiv2022

A fast computational model for circulatory dynamics:Effects of left ventricle-aorta coupling

The course of diseases such as hypertension, systolic heart failure and heart failure with a preserved ejection fraction are affected by interactions between the left ventricle (LV) and the vasculature. To study these interactions, a computationally efficient, biophysically based mathematical model for the circulatory system is presented. In a four-chamber model of the heart, the LV is represented by a previously described low-order, wall volume-preserving model that includes torsion and base-to-apex and circumferential wall shortening and lengthening, and the other chambers are represented using spherical geometries. Active and passive myocardial mechanics of all four chambers are included. The cardiac model is coupled with a wave-propagation model for the aorta and a closed lumped-parameter circulation model. Parameters for the normal heart and aorta are determined by fitting to experimental data. Changes in the timing and magnitude of pulse wave reflections by the aorta are demonstrated with changes in compliance and taper of the aorta as seen in aging (decreased compliance, increased diameter and length), and resulting effects on LV pressure-volume loops and LV fiber stress and sarcomere shortening are predicted. Effects of aging of the aorta combined with reduced LV contractile force (failing heart) are examined. In the failing heart, changes in aortic properties with aging affect stroke volume and sarcomere shortening without appreciable augmentation of aortic pressure, and the reflected pressure wave contributes an increased proportion of aortic pressure.

bioengineering↗

bioRxiv2021

Neuronal ROS-Induced Glial Lipid Droplet Formation is Altered by Loss of Alzheimers Disease-associated Genes

A growing list of Alzheimers disease (AD) genetic risk factors is being identified, but the contribution of these genetic mutations to disease remains largely unknown. Accumulating data support a role of lipid dysregulation and excessive ROS in the etiology of AD. Here, we identified cell-specific roles for eight AD risk-associated genes in ROS-induced glial lipid droplet (LD) formation. We demonstrate that ROS-induced glial LD formation requires two ABCA transporters (ABCA1 and ABCA7) in neurons, the APOE receptor (LRP1), endocytic genes (PICALM, CD2AP, and AP2A2) in glia, and retromer genes (VPS26 and VPS35) in both neurons and glia. Moreover, ROS strongly enhances A{beta}42-toxicity in flies and A{beta}42-plaque formation in mice. Finally, an ABCA1-activating peptide restores glial LD formation in the APOE4-associated loss of LD. This study places AD risk factors in a neuron-to-glia lipid transfer pathway with a critical role in protecting neurons from ROS-induced toxicity.

genetics↗

bioRxiv2019

Regulation of BMP Signaling by O-GlcNAcylation

Precise regulation of signal transduction is critical throughout organismal life, both for embryonic development and for adult homeostasis. To ensure proper spatio-temporal signal transduction, Bone Morphogenetic Protein (BMP) signaling pathways, like all other signaling pathways, are regulated by both agonists and antagonists. Here, we report identification of a previously unrecognized method of signal antagonism for Dpp (Decapentaplegic), a Drosophila BMP family member. We demonstrate that the BMP type I receptor Saxophone (Sax) functions as a Dpp receptor in the Drosophila embryonic epidermis, but that its activity is normally inhibited by the O-linked glycosyltransferase Super sex combs (Sxc). In wild-type embryos, inhibition of Saxophone (Sax) activity in the epidermis marks the BMP type I receptor Thickveins (Tkv) as the sole conduit for Dpp. In contrast, in sxc mutants, the Dpp signal is transduced by both Tkv and Sax, and elevated Dpp signaling induces errors in embryonic development that lead to embryonic death. We also demonstrate that Sax is the O-glycosylated target of Sxc and that O-glycosylation of Sax can be modulated by dietary sugar. Together, these findings link fertility to nutritive environment and point to Sax (activin receptor-like kinase 2 [ACVR1 or ALK2]) signaling as the nutrient-sensitive branch of BMP signaling. O_FIG O_LINKSMALLFIG WIDTH=199 HEIGHT=200 SRC="FIGDIR/small/784629v2_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1737655org.highwire.dtl.DTLVardef@15de1ddorg.highwire.dtl.DTLVardef@978c76org.highwire.dtl.DTLVardef@186b60e_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

developmental biology↗