Mary Jordan - Academia.edu (original) (raw)

Papers by Mary Jordan

Biophysical Journal, 2008

Numerous isotypes of the structural protein tubulin have now been characterized in various organi... more Numerous isotypes of the structural protein tubulin have now been characterized in various organisms and their expression offers a plausible explanation for observed differences affecting microtubule function in vivo. While this is an attractive hypothesis, there are only a handful of studies demonstrating a direct influence of tubulin isotype composition on the dynamic properties of microtubules. Here, we present the results of experimental assays on the assembly of microtubules from bovine brain tubulin using purified isotypes at various controlled relative concentrations. A novel data analysis is developed using recursive maps which are shown to be related to the master equation formalism. We have found striking similarities between the three isotypes of bovine tubulin studied in regard to their dynamic instability properties, except for subtle differences in their catastrophe frequencies. When mixtures of tubulin isotypes are analyzed, their nonlinear concentration dependence is modeled and interpreted in terms of lower affinities of tubulin dimers belonging to the same isotype than those that represent different isotypes indicating hitherto unsuspected influences of tubulin dimers on each other within a microtubule. Finally, we investigate the fluctuations in microtubule assembly and disassembly rates and conclude that the inherent rate variability may signify differences in the guanosine-59-triphosphate composition of the growing and shortening microtubule tips. It is the main objective of this article to develop a quantitative model of tubulin polymerization for individual isotypes and their mixtures. The possible biological significance of the observed differences is addressed.

Gynecologic Oncology, 2021

Please refer to published version for the most recent bibliographic citation information. If a pu... more Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.

Acta Horticulturae, 2005

Ethanol concentration and chlorophyll fluorescence were measured as signs of heat stress in apple... more Ethanol concentration and chlorophyll fluorescence were measured as signs of heat stress in apple fruit [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. 'Mclntosh', 'Cortland', 'Jonagold', and 'Northern Spy' apples were held at 46°C for 0, 4, 8, or 12 h. Following treatments, fruit were stored at 0°C in air and evaluated after 0, 4, 8, or 12 weeks. Peel and flesh browning, headspace ethanol concentration, and chlorophyll fluorescence (Fv/Fm) were measured. Peel browning became apparent in all 4 cultivars 4 weeks after treatment and increased during storage. Exposure to 46°C for 12 h caused severe flesh browning in all cultivars. Severity of flesh browning increased with increasing heat treatment time and storage time. Headspace ethanol concentrations immediately following 12 h heat treatments increased and were 48-, 70-, 9-, and 170- fold higher in 'Mclntosh', 'Cortland', 'Jonagold', and 'Northern Spy' apples than in the controls, respectively. Ethanol concentrations also increased in fruit treated for 8 h but not in those treated for 4 h. Ethanol concentrations were maintained or increased during the 12 weeks of storage. Heat treatments reduced chlorophyll fluorescence (Fv/Fm). One day following treatment, fruit exposed to 46°C for 12 h had Fv/Fm values that were 36%, 59%, 63%, and 36% of the control values in 'Mclntosh', 'Cortland', 'Jonagold', and 'Northern Spy', respectively. The 8 h heat treatment also decreased Fv/Fm in treated fruit, but the 4 h treatment had no effect. Fv/Fm decreased in all treatments during storage. Correlations between flesh browning and ethanol concentration ranged from 0.87 to 0.78, and flesh browning and Fv/Fm ranged from -0.91 to -0.67 depending on cultivar. The increase in ethanol production and decrease in chlorophyll fluorescence were apparent before browning was visually apparent and have the potential to predict injury that develops during storage.

Animal Cell Technology Meets Genomics, 2005

Journal of Clinical Oncology, 2006

Microtubule-stabilizing agents (MTSAs), including the taxanes and epothilones, are effective chem... more Microtubule-stabilizing agents (MTSAs), including the taxanes and epothilones, are effective chemotherapeutic agents for the treatment of many cancers. Neuropathy is a major adverse effect of MTSA-based chemotherapy, with severe peripheral neuropathy (grade 3 or 4) occurring in as many as 30% of patients treated with a MTSA. MTSA-induced neuropathy usually resolves gradually after cessation of the treatment. The most reliable method to accurately assess MTSA-induced neuropathy is by clinical evaluation, although additional techniques are being developed and evaluated. Among MTSA-induced neuropathy, the most extensively studied is that induced by taxanes; such a neuropathy usually presents as sensory neuropathy and is more common with paclitaxel than docetaxel. The incidence of MTSA-induced neuropathy seems to depend on the MTSA dose per treatment cycle, the schedule of treatment, and the duration of the infusion. Although there have been several small clinical trials with neuroprote...

Journal of Biological Chemistry, 2007

The envelope protein domain III (ED3) of West Nile virus is the major virus-specific neutralizati... more The envelope protein domain III (ED3) of West Nile virus is the major virus-specific neutralization domain and harbors most of the critical mutations that induce resistance against antibody-mediated neutralization. We investigated the molecular mechanisms of neutralization resistance by studying the biophysical perturbations of monoclonal antibody (mAb)-resistant mutations on ED3 wild type. Our results showed that although the solution structure between ED3 wild type and mutants was preserved, the mutations that confer the highest degree of resistance to mAbs showed low protein stability and high local dynamic motions. Interestingly, the latter was observed in regions outside the mutation sites, indicating long range communications within ED3. Thus, we hypothesized that the mechanisms involved in resistance to mAb neutralization may include, in addition to mutations in the epitope, long range effects among distant structural elements. This hypothesis is consistent with reported mutations in other flaviviruses whose surfaces are not exposed for the interaction with other macromolecules, yet they confer mAb neutralization resistance.

Diabetes, 1995

Diabetes is known to cause impaired endothelium-dependent relaxation of blood vessels. The purpos... more Diabetes is known to cause impaired endothelium-dependent relaxation of blood vessels. The purpose of this study was to determine whether this endothelial dysfunction is a permanent defect or is reversible after acute arginine supplementation in vitro or by surgical intervention in vivo using syngeneic pancreatic islet transplantation. Lewis rats were injected with streptozotocin to induce diabetes and were studied either 8 or 12 weeks later. Another group received syngeneic islets via intraportal injection at 8 weeks of diabetes and were allowed to become euglycemic for 4 weeks before study. Thoracic aortic rings were tethered in isolated muscle baths, contracted with a submaximal concentration of norepinephrine, and challenged with either the endotheliumdependent vasodilator acetylcholine or the endotheliumindependent vasodilator nitroglycerin. Relaxation to acetylcholine (but not nitroglycerin) was reduced in both 8-and 12-week diabetic rings compared with age-matched control rings. Preincubation of diabetic rings in vitro with L-arginine (but not D-arginine) restored relaxation to acetylcholine to normal in rings from 8-week but not 12-week diabetic animals. Plasma basic amino acids (arginine, lysine, and histidine) were reduced by diabetes, whereas other neutral or acidic amino acids were unchanged (phenylalanine, proline, and glutamate), reduced (serine, cysteine, threonine, tyrosine, tryptophan, and aspartate), or elevated (isoleucine, leucine, and valine). Islet transplantation restored to normal the changes in plasma amino acids. Elevation in blood glucose and total glycosylated hemoglobin in diabetic animals was normalized after islet transplantation. Furthermore, islet transplantation completely restored the defective endothelium-dependent relaxation to acetylcholine in diabetic rings. These studies provide evidence for the existence of reversible and irreversible stages of endothelial cell dysfunction that occur in diabetes and that preemptive surgical intervention using pancreatic islet transplantation can completely restore normal endothelial function. Diabetes

Molecular Pharmacology, 1997

The mechanism of action of a novel antiproliferative compound LY290181 [2-amino-4-(3-pyridyl)-4H-... more The mechanism of action of a novel antiproliferative compound LY290181 [2-amino-4-(3-pyridyl)-4H-naphtho(1,2-b)pyran-3carbonitrile] was characterized. LY290181 is a potent inhibitor of cell proliferation, producing 50% inhibition of vascular smooth muscle, endothelial, Chinese hamster ovary, HeLa, and human erythroleukemia cells at concentrations of 8-40 nM. Cell cycle analysis showed that LY290181 caused accumulation of smooth muscle cells at the G 2 /M phase and induced mitotic arrest in Chinese hamster ovary cells and HeLa cells. At low concentrations (3-30 nM), LY290181 blocked transition of cells from metaphase to anaphase and disrupted mitotic spindle organization. At high concentrations (Ն100 nM), LY290181 produced a concentration-dependent loss of cytoplasmic and spindle microtubules. LY290181 inhibited the polymerization of purified bovine brain microtubule protein into microtubules, and it depolymerized preformed microtubules. Using tubulin-1-anilino-8naphthalene sulfonate complex fluorescence, we have shown that LY290181 directly interacted with tubulin in a unique manner. These studies show that LY290181 induces cell growth arrest in prometaphase/metaphase, and tubulin appears to be its molecular target.

Cancer research, Sep 3, 2016

Peripheral neuropathy is a serious, dose-limiting side effect of cancer treatment with microtubul... more Peripheral neuropathy is a serious, dose-limiting side effect of cancer treatment with microtubule-targeting drugs. Symptoms present in a "stocking-glove" distribution, with longest nerves affected most acutely, suggesting a length-dependent component to the toxicity. Axonal transport of ATP-producing mitochondria along neuronal microtubules from cell body to synapse is crucial to neuronal function. We compared the effects of the drugs paclitaxel and ixapebilone that bind along the lengths of microtubules and the drugs eribulin and vincristine that bind at microtubule ends, on mitochondrial trafficking in cultured human neuronal SK-N-SH cells and on axonal transport in mouse sciatic nerves. Antiproliferative concentrations of paclitaxel and ixabepilone significantly inhibited the anterograde transport velocity of mitochondria in neuronal cells, whereas eribulin and vincristine inhibited transport only at significantly higher concentrations. Confirming these observations, a...

Cancer research, 1985

Vinepidine, a new derivative of vincristine, and three clinically used Catharanthus derivatives, ... more Vinepidine, a new derivative of vincristine, and three clinically used Catharanthus derivatives, vinblastine, vincristine, and vindesine, were examined for their abilities to inhibit net tubulin addition at the assembly ends of bovine brain microtubules at steady state. Although all four derivatives were generally similar in potency, their relative abilities to inhibit tubulin addition were distinguishable. Vinepidine and vincristine were the most potent derivatives (Ki, 0.079 +/- 0.018 (SD) microM and 0.085 +/- 0.013 microM, respectively), followed by vindesine (Ki, 0.110 +/- 0.007 microM) and vinblastine (Ki, 0.178 +/- 0.025 microM). In contrast to their relative abilities to inhibit microtubule assembly in vitro, vinblastine and its derivative, vindesine, were generally more potent than vincristine and vinepidine in inhibiting cell proliferation in culture. Vinblastine was nine times more potent than the weakest derivative, vinepidine, in B16 melanoma cells. In L-cells, vinblasti...

Cancer research, Jan 15, 1991

We have used a structure-activity approach to investigate whether the Vinca alkaloids inhibit cel... more We have used a structure-activity approach to investigate whether the Vinca alkaloids inhibit cell proliferation primarily by means of their effects on mitotic spindle microtubules or by another mechanism or by a combination of mechanisms. Five Vinca alkaloids were used to investigate the relationship in HeLa cells between inhibition of cell proliferation and blockage of mitosis, alteration of spindle organization, and depolymerization of microtubules. Indirect immunofluorescence staining of microtubules and 4,6-diamidino-2-phenylindole staining of chromatin were used to characterize the effects of the drugs on the distributions of cells in stages of the cell cycle and on the organization of microtubules and chromosomes in metaphase spindles. The microtubule polymer was isolated from cells and quantified using a competitive enzyme-linked immunoadsorbent assay for tubulin. We observed a nearly perfect coincidence between the concentration of each Vinca derivative that inhibited cell ...

The Journal of Cell Biology, 1987

The length dynamics both of microtubule-associated protein (MAP)-rich and MAP-depleted bovine bra... more The length dynamics both of microtubule-associated protein (MAP)-rich and MAP-depleted bovine brain microtubules were examined at polymer mass steady state. In both preparations, the microtubules exhibited length redistributions shortly after polymer mass steady state was attained. With time, however, both populations relaxed to a state in which no further changes in length distributions could be detected. Shearing the microtubules or diluting the microtubule suspensions transiently increased the extent to which microtubule length redistributions occurred, but again the microtubules relaxed to a state in which changes in the polymer length distributions were not detected. Under steady-state conditions of constant polymer mass and stable microtubule length distribution, both MAP-rich and MAP-depleted microtubules exhibited behavior consistent with treadmilling. MAPs strongly suppressed the magnitude of length redistributions and the steady-state treadmilling rates. These data indicat...

Molecular Biology of the Cell, 2004

The neural microtubule-associated protein tau binds to and stabilizes microtubules. Because of al... more The neural microtubule-associated protein tau binds to and stabilizes microtubules. Because of alternative mRNA splicing, tau is expressed with either 3 or 4 C-terminal repeats. Two observations indicate that differences between these tau isoforms are functionally important. First, the pattern of tau isoform expression is tightly regulated during development. Second, mutation-induced changes in tau RNA splicing cause neuronal cell death and dementia simply by altering the isoform expression ratio. To investigate whether 3- and 4-repeat tau differentially regulate microtubule behavior in cells, we microinjected physiological levels of these two isoforms into EGFP-tubulin–expressing cultured MCF7 cells and measured the effects on the dynamic instability behavior of individual microtubules by time-lapse microscopy. Both isoforms suppressed microtubule dynamics, though to different extents. Specifically, 4-repeat tau reduced the rate and extent of both growing and shortening events. In ...

Journal of Biological Chemistry, 2005

Journal of Biological Chemistry, 2011

Journal of Biological Chemistry, 2001

Journal of Biological Chemistry, 2002

Journal of Biological Chemistry, 2006

The neural microtubule-associated protein Tau binds directly to microtubules and regulates their ... more The neural microtubule-associated protein Tau binds directly to microtubules and regulates their dynamic behavior. In addition to being required for normal development, maintenance, and function of the nervous system, Tau is associated with several neurodegenerative diseases, including Alzheimer disease. One group of neurodegenerative dementias known as FTDP-17 (frontotemporal dementia with Parkinsonism linked to chromosome 17) is directly linked genetically to mutations in the tau gene, demonstrating that Tau misfunction can cause neuronal cell death and dementia. These mutations result either in amino acid substitutions in Tau or in altered Tau mRNA splicing that skews the expression ratio of wild-type 3-repeat and 4-repeat Tau isoforms. Because wild-type Tau regulates microtubule dynamics, one possible mechanism underlying Tau-mediated neurodegeneration is aberrant regulation of microtubule behavior. In this study, we microinjected normal and mutated Tau protein into cultured cells expressing fluorescent tubulin and measured the effects on the dynamic instability of individual microtubules. We found that the FTDP-17 amino acid substitutions G272V (in both 3-repeat and 4-repeat Tau contexts), ⌬K280, and P301L all exhibited markedly reduced abilities to regulate dynamic instability relative to wild-type Tau. In contrast, the FTDP-17 R406W mutation (which maps in a regulatory region outside the microtubule binding domain of Tau) did not significantly alter the ability of 3-repeat or 4-repeat Tau to regulate microtubule dynamics. Overall, these data are consistent with a loss-of-function model in which both amino acid substitutions and altered mRNA splicing in Tau lead to neurodegeneration by diminishing the ability of Tau to properly regulate microtubule dynamics.

Journal of Biological Chemistry, 2008

Mutations affecting either the structure or regulation of the microtubule-associated protein Tau ... more Mutations affecting either the structure or regulation of the microtubule-associated protein Tau cause neuronal cell death and dementia. However, the molecular mechanisms mediating these deleterious effects remain unclear. Among the most characterized activities of Tau is the ability to regulate microtubule dynamics, known to be essential for proper cell function and viability. Here we have tested the hypothesis that Tau mutations causing neurodegeneration also alter the ability of Tau to regulate the dynamic instability behaviors of microtubules. Using in vitro microtubule dynamics assays to assess average microtubule growth rates, microtubule growth rate distributions, and catastrophe frequencies, we found that all tested mutants possessing amino acid substitutions or deletions mapping to either the repeat or interrepeat regions of Tau do indeed compromise its ability to regulate microtubule dynamics. Further mutational analyses suggest a novel mechanism of Tau regulatory action based on an "alternative core" of microtubule binding and regulatory activities composed of two repeats and the interrepeat between them. In this model, the interrepeat serves as the primary regulator of microtubule dynamics, whereas the flanking repeats serve as tethers to properly position the interrepeat on the microtubule. Importantly, since there are multiple interrepeats on each Tau molecule, there are also multiple cores on each Tau molecule, each with distinct mechanistic capabilities, thereby providing significant regulatory potential. Taken together, the data are consistent with a microtubule misregulation mechanism for Tau-mediated neuronal cell death and provide a novel mechanistic model for normal and pathological Tau action.

Chemistry & Biology, 2002

The two novel taxanes, SB-T-1213 and IDN5109 (Figure 1), were synthesized from 10-deacetylbaccati... more The two novel taxanes, SB-T-1213 and IDN5109 (Figure 1), were synthesized from 10-deacetylbaccatin III 1 Department of Molecular, Cellular, and Developmental Biology and and 14␤-hydroxy-10-deacetylbaccatin III isolated from Taxus baccata and Taxus walichiana Zucc., respec