Physiological Ecology of Stress-Responsive Gene Expression in the American Lobster, Homarus americanus: Molecular Chaperones and Polyubiquitin

Homologous molecular probes were used to examine in vivo molecular chaperone and polyubiquitin gene expression patterns in the American lobster, Homarus americanus, an ectothermic marine crustacean. Following long-term laboratory acclimation to temperatures experienced during overintering in nature, juvenile lobsters failed to elicit the classical "heat-shock response'' when subjected to an acute 13°C thermal stress. Levels of mRNA coding for molecular chaperones (HSC70, HSP70, and HSP90) and polyubiquitin were not induced during thermal stress or recovery in cold-acclimated animals. These results contrasted with those for lobsters acclimated to ambient Pacific Ocean temperatures that experienced an acute stress over an equivalent thermal interval. Ambient-acclimated lobsters displayed significant inductions in the mRNA levels for both molecular chaperones and polyubiquitin. Hyper- and hypo-osmotic stress were found to significantly induce HSP90 and polyubiquitin mRNA levels in ambient-acclimated juvenile lobsters. Additionally, osmotic and thermal stress interactively altered HSP90 and polyubiquitin gene expression in animals that received both types of stress. Physiological changes over the molt cycle significantly affected gene expression in claw muscles undergoing atrophy in preparation for molting. Molecular chaperone and polyubiquitin mRNA levels differed significantly between premolt claw and abdominal muscle, which does not undergo atrophy during the premolt stages

Physiological Ecology of Stress-Responsive Gene Expression in the American Lobster, Homarus americanus: Molecular Chaperones and Polyubiquitin

Homologous molecular probes were used to examine in vivo molecular chaperone and polyubiquitin gene expression patterns in the American lobster, Homarus americanus, an ectothermic marine crustacean. Following long-term laboratory acclimation to temperatures experienced during overintering in nature, juvenile lobsters failed to elicit the classical "heat-shock response'' when subjected to an acute 13°C thermal stress. Levels of mRNA coding for molecular chaperones (HSC70, HSP70, and HSP90) and polyubiquitin were not induced during thermal stress or recovery in cold-acclimated animals. These results contrasted with those for lobsters acclimated to ambient Pacific Ocean temperatures that experienced an acute stress over an equivalent thermal interval. Ambient-acclimated lobsters displayed significant inductions in the mRNA levels for both molecular chaperones and polyubiquitin. Hyper- and hypo-osmotic stress were found to significantly induce HSP90 and polyubiquitin mRNA levels in ambient-acclimated juvenile lobsters. Additionally, osmotic and thermal stress interactively altered HSP90 and polyubiquitin gene expression in animals that received both types of stress. Physiological changes over the molt cycle significantly affected gene expression in claw muscles undergoing atrophy in preparation for molting. Molecular chaperone and polyubiquitin mRNA levels differed significantly between premolt claw and abdominal muscle, which does not undergo atrophy during the premolt stages

Osmotic Induction of Stress-Responsive Gene Expression in the Lobster Homarus americanus

Volume: 203Start Page: 331End Page: 33

The Neural Progenitor Cell-Associated Transcription Factor FoxG1 Regulates Cardiac Epicardial Cell Proliferation

The epicardium is a layer of mesothelial cells that covers the surface of the heart. During development, epicardial cells undergo epithelial-to-mesenchymal transition (EMT) to form multipotent precursors that migrate into the heart and contribute to the coronary vasculature by differentiating into adventitial fibroblasts, smooth muscle cells, and endothelial cells. Epicardial cells also provide paracrine signals to cardiac myocytes that are required for appropriate heart growth. In adult hearts, a similar process of epicardial cell EMT, migration, and differentiation occurs after myocardial infarction (MI, heart attack). Pathological cardiac hypertrophy is associated with fibrosis, negative remodeling, and reduced cardiac function. In contrast, aerobic exercises such as swimming and running promote physiological (i.e., beneficial) hypertrophy, which is associated with angiogenesis and improved cardiac function. As epicardial cell function(s) during physiological hypertrophy are poorly understood, we analyzed and compared the native epicardial cells isolated directly from the hearts of running-exercised mice and age-matched, nonrunning littermates. To obtain epicardial cells, we enzymatically digested the surfaces of whole hearts and performed magnetic-activated cell sorting (MACS) with antibodies against CD104 (integrin β4). By cDNA microarray assays, we identified genes with increased transcription in epicardial cells after running exercise; these included FoxG1, a transcription factor that controls neural progenitor cell proliferation during brain development and Snord116, a small noncoding RNA that coordinates expression of genes with epigenetic, circadian, and metabolic functions. In cultured epicardial cells, shRNA-mediated FoxG1 knockdown significantly decreased cell proliferation, as well as Snord116 expression. Our results demonstrate that FoxG1 regulates epicardial proliferation, and suggest it may affect cardiac remodeling

Bone marrow-derived mesenchymal stem cells inhibit vascular smooth muscle cell proliferation and neointimal hyperplasia after arterial injury in rats

We investigated whether mesenchymal stem cell (MSC)-based treatment could inhibit neointimal hyperplasia in a rat model of carotid arterial injury and explored potential mechanisms underlying the positive effects of MSC therapy on vascular remodeling/repair. Sprague-Dawley rats underwent balloon injury to their right carotid arteries. After 2 days, we administered cultured MSCs from bone marrow of GFP-transgenic rats (0.8 × 106 cells, n = 10) or vehicle (controls, n = 10) to adventitial sites of the injured arteries. As an additional control, some rats received a higher dose of MSCs by systemic infusion (3 × 106 cells, tail vein; n = 4). Local vascular MSC administration significantly prevented neointimal hyperplasia (intima/media ratio) and reduced the percentage of Ki67 + proliferating cells in arterial walls by 14 days after treatment, despite little evidence of long-term MSC engraftment. Notably, systemic MSC infusion did not alter neointimal formation. By immunohistochemistry, compared with neointimal cells of controls, cells in MSC-treated arteries expressed reduced levels of embryonic myosin heavy chain and RM-4, an inflammatory cell marker. In the presence of platelet-derived growth factor (PDGF-BB), conditioned medium from MSCs increased p27 protein levels and significantly attenuated VSMC proliferation in culture. Furthermore, MSC-conditioned medium suppressed the expression of inflammatory cytokines and RM-4 in PDGF-BB-treated VSMCs. Thus, perivascular administration of MSCs may improve restenosis after vascular injury through paracrine effects that modulate VSMC inflammatory phenotype. Keywords: Mesenchymal stem cells, Vascular smooth muscle cells, Neointimal hyperplasia, Stem cell-secreted factor

Pre-Treatment with Amifostine Protects against Cyclophosphamide-Induced Disruption of Taste in Mice

<div><p>Cyclophosphamide (CYP), a commonly prescribed chemotherapy drug, has multiple adverse side effects including alteration of taste. The effects on taste are a cause of concern for patients as changes in taste are often associated with loss of appetite, malnutrition, poor recovery and reduced quality of life. Amifostine is a cytoprotective agent that was previously shown to be effective in preventing chemotherapy-induced mucositis and nephrotoxicity. Here we determined its ability to protect against chemotherapy-induced damage to taste buds using a mouse model of CYP injury. We conducted detection threshold tests to measure changes in sucrose taste sensitivity and found that administration of amifostine 30 mins prior to CYP injection protected against CYP-induced loss in taste sensitivity. Morphological studies showed that pre-treatment with amifostine prevented CYP-induced reduction in the number of fungiform taste papillae and increased the number of taste buds. Immunohistochemical assays for markers of the cell cycle showed that amifostine administration prevented CYP-induced inhibition of cell proliferation and also protected against loss of mature taste cells after CYP exposure. Our results indicate that treatment of cancer patients with amifostine prior to chemotherapy may improve their sensitivity for taste stimuli and protect the taste system from the detrimental effects of chemotherapy.</p> </div

Representative images of PLCβ2-positive cells (red) in fungiform and circumvallate taste buds on days 4, 7, 10 and 16 post-injection in saline-, CYP- or AMF/CYP-injected mice.

<p>Sytox green was used as a nuclear marker. There was a reduction in the number of PLCβ2-positive cells in fungiform and circumvallate taste buds on day 4 in CYP-injected mice but not in AMF/CYP-injected mice. The bar graphs illustrate the mean (± SEM) number of PLCβ2-positive cells in fungiform (upper graph) and circumvallate (lower graph) taste buds across days in each drug group. (<b>a</b>) In fungiform taste buds, there was a reduction in the number of PLCβ2-positive cells on day 4, 7 and 10 in CYP-injected mice and on day 7 in AMF/CYP-injected mice. Scale bar = 25 µm. (<b>b</b>) In circumvallate taste buds, there was a reduction in the number of PLCβ2-positive cells on day 7 and 10 in CYP-injected mice and on day 7 in AMF/CYP-injected mice. Scale bar = 50 µm. (*** <i>P</i><0.001;** <i>P</i><0.01;* <i>P</i><0.05).</p