Biology subjects

Chang, K.

Publications and source records attributed to Chang, K..

3 recordsLinked to original sources

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

Drosophila Kruppel homolog 1 represses lipolysis through interaction with dFOXO

Transcriptional coordination is a vital process contributing to metabolic homeostasis. As one of the key nodes in the metabolic network, the forkhead transcription factor FOXO has been shown to interact with diverse transcription co-factors and integrate signals from multiple pathways to control metabolism, oxidative stress response, and cell cycle. Recently, insulin/FOXO signaling has been implicated in the regulation of insect development via the interaction with insect hormones, such as ecdysone and juvenile hormone. In this study, we identified an interaction between dFOXO and the zinc finger transcription factor Kruppel homolog 1 (Kr-h1), one of the key players in juvenile hormone signaling in Drosophila. We found that Kr-h1 mutants have reduced triglyceride storage, decreased insulin signaling and delayed larval development. Notably, Kr-h1 physically and genetically interacts with dFOXO in vitro and in vivo to regulate the transcriptional activation of adipose lipase brummer (bmm). The transcriptional co-regulation by Kr-h1 and dFOXO may represent a broad mechanism by which Kruppel-like factors integrate with insulin signaling to maintain metabolic homeostasis and coordinate organism growth.

genetics↗

bioRxiv2017

Heart-Specific Activin Signaling Promotes Cardiomyopathy And Organismal Aging Through Autophagy Inhibition

Age-dependent loss of cardiac tissue homeostasis largely impacts heart performance and contributes significantly to cardiovascular diseases later in life. Cellular quality control machinery, such as autophagy/lysosome system, plays a crucial role in maintaining cardiac health and preventing age-induced cardiomyopathy and heart failure. However, how aging alters the autophagy/lysosome system to impact cardiac function remains largely unknown. Here using Drosophila heart as a model system, we show that activin signaling, a member of TGF-beta superfamily, negatively regulates cardiac autophagy and cardiac health during aging. We found that cardiac-specific knockdown of Daw, an activin-like protein in Drosophila, increased cardiac autophagy and prevented age-related cardiac dysfunction, including arrhythmia and bradycardia (slow heart rate). Inhibition of autophagy blocked Daw knockdown-mediated cardioprotection. Consistently, cardiac-specific expression of constitutively activated activin type I receptor Babo disrupted cardiac function at young ages. Intriguingly, the key autophagy regulator, mechanistic target of rapamycin complex 1 (mTORC1), was not involved in activin-mediated autophagy. Instead, activin signaling genetically interacted with Rictor, the key subunit of mTORC2, to regulate autophagy and cardiac aging. Knockdown of Daw increased the mRNA expression of Rictor and the phosphorylation of AKT in fly hearts. Finally, cardiac-specific silencing of Daw not only improved cardiac health, but also prolonged lifespan. Thus, our findings highlight an emerging role of activin signaling and mTORC2 in the regulation of autophagy and cardiac aging.

genetics↗