ORCID Profile
0000-0002-2402-4483
Current Organisation
University of Adelaide
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 07-2021
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 29-07-2016
Abstract: Aquaporin-1 (AQP1) is a major intrinsic protein that facilitates flux of water and other small solutes across cell membranes. In addition to its function as a water channel in maintaining fluid homeostasis, AQP1 also acts as a nonselective cation channel gated by cGMP, a property shown previously to facilitate rapid cell migration in a AQP1-expressing colon cancer cell line. Here we report two new modulators of AQP1 channels, bacopaside I and bacopaside II, isolated from the medicinal plant Bacopa monnieri Screening was conducted in the Xenopus oocyte expression system, using quantitative swelling and two-electrode voltage cl techniques. Results showed bacopaside I blocked both the water (IC50 117 μM) and ion channel activities of AQP1 but did not alter AQP4 activity, whereas bacopaside II selectively blocked the AQP1 water channel (IC50 18 μM) without impairing the ionic conductance. These results fit with predictions from in silico molecular modeling. Both bacopasides were tested in migration assays using HT29 and SW480 colon cancer cell lines, with high and low levels of AQP1 expression, respectively. Bacopaside I (IC50 48 μM) and bacopaside II (IC50 14 μM) impaired migration of HT29 cells but had minimal effect on SW480 cell migration. Our results are the first to identify differential AQP1 modulators isolated from a medicinal plant. Bacopasides could serve as novel lead compounds for pharmaceutic development of selective aquaporin modulators.
Publisher: Portland Press Ltd.
Date: 31-10-2018
DOI: 10.1042/BSR20180698
Abstract: Cell migration is important in many physiological and pathological processes. Mechanisms of two-dimensional cell migration have been investigated most commonly by evaluating rates of cell migration into linearly scratched zones on the surfaces of culture plates. Here, we present a detailed description of a simple adaptation for the well-known and popular wound closure assay, using a circular wound instead of a straight line. This method demonstrates improved precision, reproducibility, and s ling objectivity for measurements of wound sizes as compared with classic scratch assays, enabling more accurate calculations of migration rate. The added benefits of the method are simplicity and low cost as compared with commercially available assays for generating circular wounds.
Publisher: Frontiers Media SA
Date: 25-04-2018
Publisher: Elsevier BV
Date: 11-2022
Publisher: Frontiers Media SA
Date: 26-04-2019
Publisher: Elsevier BV
Date: 11-2023
Publisher: Frontiers Media SA
Date: 27-04-2018
Publisher: Springer Science and Business Media LLC
Date: 02-09-2019
DOI: 10.1038/S41598-019-49045-9
Abstract: Aquaporin-1 (AQP1) has been proposed as a dual water and cation channel that when upregulated in cancers enhances cell migration rates however, the mechanism remains unknown. Previous work identified AqB011 as an inhibitor of the gated human AQP1 cation conductance, and bacopaside II as a blocker of AQP1 water pores. In two colorectal adenocarcinoma cell lines, high levels of AQP1 transcript were confirmed in HT29, and low levels in SW480 cells, by quantitative PCR (polymerase chain reaction). Comparable differences in membrane AQP1 protein levels were demonstrated by immunofluorescence imaging. Migration rates were quantified using circular wound closure assays and live-cell tracking. AqB011 and bacopaside II, applied in combination, produced greater inhibitory effects on cell migration than did either agent alone. The high efficacy of AqB011 alone and in combination with bacopaside II in slowing HT29 cell motility correlated with abundant membrane localization of AQP1 protein. In SW480, neither agent alone was effective in blocking cell motility however, combined application did cause inhibition of motility, consistent with low levels of membrane AQP1 expression. Bacopaside alone or combined with AqB011 also significantly impaired lamellipodial formation in both cell lines. Knockdown of AQP1 with siRNA (confirmed by quantitative PCR) reduced the effectiveness of the combined inhibitors, confirming AQP1 as a target of action. Invasiveness measured using transwell filters layered with extracellular matrix in both cell lines was inhibited by AqB011, with a greater potency in HT29 than SW480. A side effect of bacopaside II at high doses was a potentiation of invasiveness, that was reversed by AqB011. Results here are the first to demonstrate that combined block of the AQP1 ion channel and water pores is more potent in impairing motility across erse classes of colon cancer cells than single agents alone.
Publisher: Elsevier BV
Date: 12-2022
DOI: 10.1016/J.EXER.2022.109249
Abstract: Previously we identified B6.EDA
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 07-02-2022
DOI: 10.1167/IOVS.63.2.12
Publisher: Cold Spring Harbor Laboratory
Date: 07-2020
DOI: 10.1101/2020.06.30.180653
Abstract: Mechanosensitivity of the trabecular meshwork (TM) is a key determinant of intraocular pressure (IOP) yet our understanding of the molecular mechanisms that subserve it remains in its infancy. Here, we show that mechanosensitive Piezo1 channels modulate the TM pressure response via calcium signaling and dynamics of the conventional outflow pathway. Pressure steps evoked fast, inactivating cation currents and calcium signals that were inhibited by Ruthenium Red, GsMTx4 and Piezo1 shRNA. Piezo1 expression was confirmed by transcript and protein analysis, and by visualizing Yoda1-mediated currents and [Ca 2+ ] i elevations in primary human TM cells. Piezo1 activation was obligatory for transduction of physiological shear stress and was coupled to reorganization of F-actin cytoskeleton and focal adhesions. The importance of Piezo1 channels as pressure sensors was shown by the GsMTx4 -dependence of the pressure-evoked current and conventional outflow function. We also demonstrate that Piezo1 collaborates with the stretch-activated TRPV4 channel, which mediated slow, delayed currents to pressure steps. Collectively, these results suggest that TM mechanosensitivity utilizes kinetically, regulatory and functionally distinct pressure transducers to inform the cells about force-sensing contexts. Piezo1-dependent control of shear flow sensing, calcium homeostasis, cytoskeletal dynamics and pressure-dependent outflow suggests a novel potential therapeutic target for treating glaucoma. Trabecular meshwork (TM) is a highly mechanosensitive tissue in the eye that regulates intraocular pressure through the control of aqueous humor drainage. Its dysfunction underlies the progression of glaucoma but neither the mechanisms through which TM cells sense pressure nor their role in aqueous humor outflow are understood at the molecular level. We identified the Piezo1 channel as a key TM transducer of tensile stretch, shear flow and pressure. Its activation resulted in intracellular signals that altered organization of the cytoskeleton and cell-extracellular matrix contacts, and modulated the trabecular component of aqueous outflow whereas another channel, TRPV4, mediated a delayed mechanoresponse. These findings provide a new mechanistic framework for trabecular mechanotransduction and its role in the regulation of fast fluctuations in ocular pressure, as well as chronic remodeling of TM architecture that epitomizes glaucoma.
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 26-06-2023
DOI: 10.1167/IOVS.64.7.36
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 14-10-2015
Publisher: Frontiers Media SA
Date: 17-03-2022
DOI: 10.3389/FCELL.2022.855097
Abstract: Polymorphisms in the CAV1/2 gene loci impart increased risk for primary open-angle glaucoma (POAG). CAV1 encodes caveolin-1 (Cav1), which is required for biosynthesis of plasma membrane invaginations called caveolae. Cav1 knockout mice exhibit elevated intraocular pressure (IOP) and decreased outflow facility, but the mechanistic role of Cav1 in IOP homeostasis is unknown. We hypothesized that caveolae sequester/inhibit RhoA, to regulate trabecular meshwork (TM) mechanosensing and contractile tone. Using phosphorylated myosin light chain (pMLC) as a surrogate indicator for Rho/ROCK activity and contractile tone, we found that pMLC was elevated in Cav1-deficient TM cells compared to control (131 ± 10%, n = 10, p = 0.016). Elevation of pMLC levels following Cav1 knockdown occurred in cells on a soft surface (137 ± 7%, n = 24, p & 0.0001), but not on a hard surface (122 ± 17%, n = 12, p = 0.22). In Cav1-deficient TM cells where pMLC was elevated, Rho activity was also increased (123 ± 7%, n = 6, p = 0.017), suggesting activation of the Rho/ROCK pathway. Cyclic stretch reduced pMLC/MLC levels in TM cells (69 ± 7% n = 9, p = 0.002) and in Cav1-deficient TM cells, although not significantly (77 ± 11% n = 10, p = 0.059). Treatment with the Cav1 scaffolding domain mimetic, cavtratin (1 μM) caused a reduction in pMLC (70 ± 5% n = 7, p = 0.001), as did treatment with the scaffolding domain mutant cavnoxin (1 μM) (82 ± 7% n = 7, p = 0.04). Data suggest that caveolae differentially regulate RhoA signaling, and that caveolae participate in TM mechanotransduction. Cav1 regulation of these key TM functions provide evidence for underlying mechanisms linking polymorphisms in the Cav1/2 gene loci with increased POAG risk.
Publisher: Wiley
Date: 11-01-2018
Abstract: Aquaporin (AQP) channels in the major intrinsic protein (MIP) family are known to facilitate transmembrane water fluxes in prokaryotes and eukaryotes. Some classes of AQPs also conduct ions, glycerol, urea, CO
Publisher: Wiley
Date: 12-12-2020
DOI: 10.1113/JP281011
Abstract: Trabecular meshwork (TM) is a highly mechanosensitive tissue in the eye that regulates intraocular pressure through the control of aqueous humour drainage. Its dysfunction underlies the progression of glaucoma but neither the mechanisms through which TM cells sense pressure nor their role in aqueous humour outflow are understood at the molecular level. We identified the Piezo1 channel as a key TM transducer of tensile stretch, shear flow and pressure. Its activation resulted in intracellular signals that altered organization of the cytoskeleton and cell‐extracellular matrix contacts and modulated the trabecular component of aqueous outflow whereas another channel, TRPV4, mediated a delayed mechanoresponse. This study helps elucidate basic mechanotransduction properties that may contribute to intraocular pressure regulation in the vertebrate eye. Chronic elevations in intraocular pressure (IOP) can cause blindness by compromising the function of trabecular meshwork (TM) cells in the anterior eye, but how these cells sense and transduce pressure stimuli is poorly understood. Here, we demonstrate functional expression of two mechanically activated channels in human TM cells. Pressure‐induced cell stretch evoked a rapid increase in transmembrane current that was inhibited by antagonists of the mechanogated channel Piezo1, Ruthenium Red and GsMTx4, and attenuated in Piezo1‐deficient cells. The majority of TM cells exhibited a delayed stretch‐activated current that was mediated independently of Piezo1 by TRPV4 (transient receptor potential cation channel, subfamily V, member 4) channels. Piezo1 functions as the principal TM transducer of physiological levels of shear stress, with both shear and the Piezo1 agonist Yoda1 increasing the number of focal cell‐matrix contacts. Analysis of TM‐dependent fluid drainage from the anterior eye showed significant inhibition by GsMTx4. Collectively, these results suggest that TM mechanosensitivity utilizes kinetically, regulatory and functionally distinct pressure transducers to inform the cells about force‐sensing contexts. Piezo1‐dependent control of shear flow sensing, calcium homeostasis, cytoskeletal dynamics and pressure‐dependent outflow suggests potential for a novel therapeutic target in treating glaucoma.
Publisher: Cold Spring Harbor Laboratory
Date: 19-12-2018
DOI: 10.1101/500124
Abstract: Cancer metastasis is a major cause of death. Traditional Chinese medicines (TCM) are promising sources of new anti-metastatic agents. Compound Kushen Injection (CKI), extracted from medicinal plants, Kushen (Sophora flavescens) and Baituling (Heterosmilax chinensis), contains a mixture of alkaloids and flavonoids known to disrupt cell cycle and induce apoptosis in breast cancer (MCF7). However, effects on cancer cell migration and invasion have remained unknown. CKI, fractionated mixtures, and single identified components were tested in migration assays with colon (HT-29, SW-480, DLD-1), brain (U-87 MG, U-251 MG), and breast (MDA-MB-231) cancer cell lines. Human embryonic kidney (HEK-293) and human foreskin fibroblast (HFF) served as non-cancerous controls. Wound closure, transwell invasion, and live cell imaging assays showed that CKI reduced motility in all eight cell lines. The greatest inhibition of migration occurred in HT-29 and MDA-MB-231, and the least in HEK-293. Fractionation and reconstitution of CKI showed that combinations of compounds were required for activity. Live cell imaging confirmed CKI strongly reduced migration of HT-29 and MDA-MB-231 cells, moderately slowed brain cancer cells, and had no effect on HEK-293. CKI uniformly blocked invasiveness through extracellular matrix. Apoptosis was increased by CKI in MDA-MB-231 cells but not in non-cancerous cells. Cell viability in CKI was unaffected in all cell lines. Transcriptomic analyses of MDA-MB-231 with and without CKI indicated down-regulated expression of actin cytoskeletal and focal adhesion genes, consistent with the observed impairment of cell migration. The pharmacological complexity of CKI is important for its effective block of cancer cell migration and invasion.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 11-03-2019
Abstract: This is the first work to use a newly designed Li
No related grants have been discovered for Michael Lucio De Ieso.