Biology subjects

Miller, L. R.

Publications and source records attributed to Miller, L. R..

4 recordsLinked to original sources

bioRxiv2026

mTOR drives cerebrovascular dysfunction and blood-brain barrier breakdown in a model of Alzheimers disease with cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is characterized by the deposition of amyloid {beta} fibrils (A{beta}) within walls of the cerebrovasculature and contributes to intracerebral hemorrhage, ischemic stroke, and cognitive dysfunction in patients with Alzheimers disease (AD) and in non-pathological aging. Previous studies have shown that mTOR drives cerebrovascular dysfunction and cognitive impairment observed in AD, vascular cognitive impairment, and normative aging. However, the mechanisms by which mTOR contributes to CAA are unknown. Here, we show that mTOR drives the accumulation of fibrillar vascular A{beta} lesions in the Tg2576 Model of AD with CAA (using equal numbers of female and male mice), which directly impair endothelium-dependent cerebrovascular reactivity. Additionally, we found that blood-brain barrier (BBB) breakdown and remodeling of tight junction proteins, dependent on mTOR, are associated with increased cerebral microhemorrhages. Finally, we show that mTOR contributes to neurovascular uncoupling in Tg2576 AD mice through nNOS dysfunction and inhibition of non-nitric oxide synthase-dependent contributions to neurovascular coupling (NVC). Contextual memory impairments were ameliorated by the mTOR inhibitor rapamycin. Improvements in memory were associated with reduced cerebrovascular A{beta} fibril accumulation, enhanced endothelium-dependent vasodilation, reduced fibrillar A{beta} load, restoration of BBB integrity, attenuation of intracerebral microhemorrhage, and restoration of NVC. These data indicate that mTOR drives vascular accumulation of fibrillar A{beta}, including those associated with brain vasculature, and mediates cerebrovascular dysfunction in a model of AD with CAA. Thus, mTOR inhibitors represent a promising treatment option for patients with CAA and AD.

neuroscience↗

bioRxiv2020

Acyl-lipid desaturases and Vipp1 cooperate in cyanobacteria to produce novel omega-3 PUFA-containing glycolipids

BackgroundDietary omega-3 (n-3), long chain (LC-, [≥] 20 carbons), polyunsaturated fatty acids (PUFAs) derived largely from marine animal sources protect against inflammatory processes and enhance brain development and function. With the depletion of natural stocks of marine animal sources and an increasing demand for n-3 LC-PUFAs, alternative, sustainable supplies are urgently needed. As a result, n-3 18 carbon and LC-PUFAs are being generated from plant or algal sources, either by engineering new biosynthetic pathways or by augmenting existing systems. ResultsWe utilized an engineered plasmid encoding two cyanobacterial acyl-lipid desaturases (DesB and DesD, encoding {Delta}15 and {Delta}6 desaturases, respectively) and "vesicle-inducing protein in plastids" (Vipp1) to induce production of stearidonic acid (SDA,18:4 n-3) at high levels in three strains of cyanobacteria (10, 17 and 27% of total lipids in Anabaena sp. PCC7120, Synechococcus sp. PCC7002, and Leptolyngbya sp. strain BL0902, respectively). Lipidomic analysis revealed that in addition to SDA, the rare anti-inflammatory n-3 LC-PUFA eicosatetraenoic acid (ETA, 20:4 n-3) was synthesized in these engineered strains, and [~]99% of SDA and ETA was complexed to bioavailable monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) species. Importantly, novel molecular species containing alpha-linolenic acid (ALA), SDA and/or ETA in both acyl positions of MGDG and DGDG were observed in the engineered Leptolyngbya and Synechococcus strains, suggesting that these could provide a rich source of anti-inflammatory molecules. ConclusionsOverall, this technology utilizes solar energy, consumes carbon dioxide, and produces large amounts of nutritionally-important n-3 PUFAs and LC-PUFAs. Importantly, it can generate previously-undescribed, highly bioavailable, anti-inflammatory galactosyl lipids. This technology could therefore be transformative in protecting ocean fisheries and augmenting the nutritional quality of human and animal food products. Broader ContextDietary omega-3 (n-3), long chain polyunsaturated fatty acids (LC-PUFAs) typically found in marine products such as fish and krill oil are beneficial to human health. In addition to human consumption, most of the global supply of n-3 LC-PUFAs is used as dietary components for aquaculture. Marked increases in usage have created an intense demand for more sustainable, stable and bioavailable forms of n-3 PUFAs and LC-PUFAs. We utilized an engineered plasmid to dramatically enhance the production of 18-carbon and n-3 LC-PUFAs in three strains of autotrophic cyanobacteria. While the sustainable generation of highly valued and bioavailable nutritional lipid products is the primary goal, additional benefits include the generation of oxygen as a co-product with the consumption of only carbon dioxide as the carbon source and solar radiation as the energy source. This technology could be transformative in protecting ocean fisheries and augmenting the nutritional quality of human and animal food products. Additionally, these engineered cyanobacteria can generate previously undescribed, highly bioavailable, anti-inflammatory galactosyl lipids.

molecular biology↗

bioRxiv2017

ESCRT-III acts in scissioning new peroxisomes from the ER

Dynamic control of peroxisome proliferation is integral to the peroxisomes many functions. A breakdown in the ability of cells to form peroxisomes is linked to many human health issues, including defense against infectious agents, cancer, aging, heart disease, obesity and diabetes, and forms the basis of a spectrum of peroxisomal genetic disorders that cause severe neuropathologies. The ER serves as a source for preperoxisomal vesicles (PPVs) that mature into peroxisomes during de novo peroxisome biogenesis and to support growth and division of existing peroxisomes. However, the mechanism of PPV formation and release from the ER remains poorly understood. Here we show that the evolutionarily ancient endosomal sorting complexes required for transport (ESCRT)-III are peroxisome biogenesis factors that function to cleave PPVs budding from the ER into the cytosol. Using comprehensive morphological and genetic assays of peroxisome formation and function we find that absence of ESCRT-III proteins impedes de novo peroxisome formation and results in an aberrant peroxisome population in vivo. Using a cell-free PPV budding assay we show that ESCRT-III proteins Vps20 and Snf7 are required to release PPVs from the ER. ESCRT-III is therefore a positive effector of membrane scission for vesicles budding both away from and towards the cytosol, a finding that has important implications for the evolutionary timing of emergence of peroxisomes and the rest of the internal membrane architecture of the eukaryotic cell.

cell biology↗

bioRxiv2017

An indicator cell assay for blood-based diagnostics

We have established proof of principle for the Indicator Cell Assay Platform (iCAP), a broadly applicable tool for blood-based diagnostics that uses specifically-selected, standardized cells as biosensors, relying on their innate ability to integrate and respond to diverse signals present in patients blood. To develop an assay, indicator cells are exposed in vitro to serum from case or control subjects and their global differential response patterns are used to train reliable, cost-effective disease classifiers based on a small number of features. In a feasibility study, the iCAP detected pre-symptomatic disease in a murine model of amyotrophic lateral sclerosis (ALS) with 94% accuracy (p-Value=3.81E-6) and correctly identified samples from a murine Huntingtons disease model as non-carriers of ALS. In a preliminary human disease assay, the iCAP detected early stage Alzheimers disease with 72% cross-validated accuracy (p-Value=3.10E-3). For both assays, iCAP features were enriched for disease-related genes, supporting the assays relevance for disease research.

systems biology↗