Digital Commons Network^™

The Toxicity Of Nanoparticles Depends On Multiple Molecular And Physicochemical Mechanisms, Yue-Wern Huang, Melissa Cambre, Han-Jung Lee

Biological Sciences Faculty Research & Creative Works

Nanotechnology is an emerging discipline that studies matters at the nanoscale level. Eventually, the goal is to manipulate matters at the atomic level to serve mankind. One growing area in nanotechnology is biomedical applications, which involve disease management and the discovery of basic biological principles. In this review, we discuss characteristics of nanomaterials, with an emphasis on transition metal oxide nanoparticles that influence cytotoxicity. Identification of those properties may lead to the design of more efficient and safer nanosized products for various industrial purposes and provide guidance for assessment of human and environmental health risk. We then investigate biochemical and …

Oxidative Stress Disruption Of Receptor-Mediated Calcium Signaling Mechanisms, Tso-Hao Tang, Chiung-Tan Chang, Hsiu-Jen Wang, Joshua Erickson, Rhett A. Reichard, Alexis Martin, Erica Shannon, Adam L. Martin, Yue-Wern Huang, Robert Aronstam

Biological Sciences Faculty Research & Creative Works

Background: Oxidative stress increases the cytosolic content of calcium in the cytoplasm through a combination of effects on calcium pumps, exchangers, channels and binding proteins. In this study, oxidative stress was produced by exposure to tert-butyl hydroperoxide (tBHP); cell viability was assessed using a dye reduction assay; receptor binding was characterized using [³H]N-methylscopolamine ([³H]MS); and cytosolic and luminal endoplasmic reticulum (ER) calcium concentrations ([Ca²⁺]_i and [Ca²⁺]_L, respectively) were measured by fluorescent imaging.

Results: Activation of M3 muscarinic receptors induced a biphasic increase in [Ca²⁺] …

Honokiol Blocks Store Operated Calcium Entry In Cho Cells Expressing The M3 Muscarinic Receptor: Honokiol And Muscarinic Signaling, Hsiu-Jen Wang, Alexis Martin, Po-Kuan Chao, Rhett A. Reichard, Adam L. Martin, Yue-Wern Huang, Ming-Huan Chan, Robert Aronstam

Biological Sciences Faculty Research & Creative Works

Background: Honokiol, a cell-permeable phenolic compound derived from the bark of magnolia trees and present in Asian herbal teas, has a unique array of pharmacological actions, including the inhibition of multiple autonomic responses. We determined the effects of honokiol on calcium signaling underlying transmission mediated by human M3 muscarinic receptors expressed in Chinese hamster ovary (CHO) cells. Receptor binding was determined in radiolabelled ligand binding assays; changes in intracellular calcium concentrations were determined using a fura-2 ratiometric imaging protocol; cytotoxicity was determined using a dye reduction assay.

Results: Honokiol had a potent (EC50 ≈ 5 μmol/l) inhibitory effect on store …

Toxicity Of Transition Metal Oxide Nanoparticles: Recent Insights From In Vitro Studies, Yue-Wern Huang, Chi-Heng Wu, Robert Aronstam

Biological Sciences Faculty Research & Creative Works

Nanotechnology has evolved to play a prominent role in our economy. Increased use of nanomaterials poses potential human health risk. It is therefore critical to understand the nature and origin of the toxicity imposed by nanomaterials (nanotoxicity). In this article we review the toxicity of the transition metal oxides in the 4th period that are widely used in industry and biotechnology. Nanoparticle toxicity is compellingly related to oxidative stress and alteration of calcium homeostasis, gene expression, pro-inflammatory responses, and cellular signaling events. The precise physicochemical properties that dictate the toxicity of nanoparticles have yet to be defined, but may include …

The Multiple Roles Of Cyk1p In The Assembly And Function Of The Actomyosin Ring In Budding Yeast, Katie Shannon, Rong Li

Biological Sciences Faculty Research & Creative Works

The budding yeast IQGAP-like protein Cyk1p/Iqg1p localizes to the mother-bud junction during anaphase and has been shown to be required for the completion of cytokinesis. In this study, video microscopy analysis of cells expressing green fluorescent protein-tagged Cyk1p/Iqg1p demonstrates that Cyk1p/Iqg1p is a dynamic component of the contractile ring during cytokinesis. Furthermore, in the absence of Cyk1p/Iqg1p, myosin II fails to undergo the contraction-like size change at the end of mitosis. To understand the mechanistic role of Cyk1p/Iqg1p in actomyosin ring assembly and dynamics, we have investigated the role of the structural domains that Cyk1p/Iqg1p shares with IQGAPs. An amino …