Biology subjects

Hau, A.

Publications and source records attributed to Hau, A..

3 recordsLinked to original sources

bioRxiv2023

Human light meromyosin mutations linked to skeletal myopathies disrupt the coiled coil structure and myosin head sequestration

Myosin heavy chains encoded by MYH7 and MYH2 are among the most abundant proteins in human skeletal muscle. After decades of intense research using a wide range of biophysical and biological approaches, their functions have begun to be elucidated. Despite this, it remains unclear how mutations in these genes and resultant proteins disrupt myosin structure and function, inducing pathological states and skeletal myopathies termed myosinopathies. Here, we have analysed the effects of several common MYH7 and MYH2 mutations located in light meromyosin (LMM) using a broad range of approaches. We determined the secondary structure and filament forming capabilities of expressed and purified LMM constructs in vitro, performed in-silico modelling of LMM constructs, and evaluated the incorporation of eGFP-myosin heavy chain constructs into sarcomeres in cultured myotubes. Using muscle biopsies from patients, we applied Mant-ATP chase protocols to estimate the proportion of myosin heads that were super-relaxed, X-ray diffraction measurements to estimate myosin head order and myofibre mechanics to investigate contractile function. We found that human MYH7 and MYH2 LMM mutations commonly disrupt myosin coiled-coil structure and packing of filaments in vitro; decrease the myosin super-relaxed state in vivo and increase the basal myosin ATP consumption; but are not associated with myofibre contractile deficits. Altogether, these findings indicate that the structural remodelling resulting from LMM mutations induces a pathogenic state in which formation of shutdown heads is impaired, thus increasing myosin head ATP demand in the filaments, rather than affecting contractility. These key findings will help in the design of future therapies for myosinopathies.

physiology↗

bioRxiv2018

Recombinant expression of Proteorhodopsin and biofilm regulators in Escherichia coli for nanoparticle binding and removal in a wastewater treatment model

The small size of nanoparticles is both an advantage and a problem. Their high surface-area-to-volume ratio enables novel medical, industrial, and commercial applications. However, their small size also allows them to evade conventional filtration during water treatment, posing health risks to humans, plants, and aquatic life. This project aims to remove nanoparticles during wastewater treatment using genetically modified Escherichia coli in two ways: 1) binding citrate-capped nanoparticles with the membrane protein Proteorhodopsin, and 2) trapping nanoparticles using Escherichia coli biofilm produced by overexpressing two regulators: OmpR234 and CsgD. We demonstrate experimentally that Escherichia coli expressing Proteorhodopsin binds to 60 nm citrate-capped silver nanoparticles. We also successfully upregulate biofilm production and show that Escherichia coli biofilms are able to trap 30 nm gold particles. Finally, both Proteorhodopsin and biofilm approaches are able to bind and remove nanoparticles in simulated wastewater treatment tanks. We envision integrating our trapping system in both rural and urban wastewater treatment plants to efficiently capture all nanoparticles before treated water is released into the environment.\n\nFinancial DisclosureThis work was funded by the Taipei American School. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.\n\nCompeting InterestsThe authors have declared that no competing interests exist.\n\nEthics StatementN/A\n\nData AvailabilityYes - all data are fully available without restriction. Sequences for the plasmids used in this study are available through the Registry of Standard Biological Parts. Links to raw data are included in Supplementary Information.

synthetic biology↗

bioRxiv2017

The elephant in the room- Universal coverage for Costly treatments in an upper middle income country

BackgroundUpper middle income countries have made substantial progress towards universal health coverage. We investigated whether the coverage extended to diseases that incur catastrophic health spending, the contribution of pooled financing and the factors driving it in Malaysia.\n\nMethodsWe adapted the WHO definition of catastrophic health spending to define costly treatment as one that cost, at prevailing market price, more than 10% of the median annual household income in Malaysia. Coverage is defined as the proportion of patients in a year who were in need of a treatment and who received it. Data to estimate coverage and financing were extracted from the published and grey literature, as well as secondary data sources available on disease epidemiology and healthcare in Malaysia.\n\nResultsWe found coverage varies from universal for dialysis, cataract surgery, medicines for organ transplant and CML, to practically none for HCV, stroke, psoriasis and epilepsy surgery. Coverage of targeted therapies for solid cancers, knee replacement surgery, anti-TNF for arthritis and coagulation factors for haemophilia were poor while iron chelation for thalassemia, coronary revacularization, epoetin and anti-retrovirals were barely adequate. Coverage correlates negatively (r=-0.82) with health benefits foregone, and is entirely driven by the contribution of pooled financing (r=0.99 p<0.0001). The relative effectiveness of a treatment, its budget impact, media coverage and political influence of the disease area have little influence on financing. Only effectiveness of the leadership representing the therapy area is influential; an increase in one point on the leadership effectiveness scale is associated with 30% increase in the contribution of pooled financing.\n\nConclusionCoverage for catastrophically costly treatments is uneven and inequitable in Malaysia, despite most of these are affordable. Decisions on coverage are driven by political-economic consideration.

epidemiology↗