Biomedical subjects

Gary Weisinger

Publications and source records attributed to Gary Weisinger.

7 recordsLinked to original sources

PubMed2006

The 5 lipoxygenase system in the vasculature: emerging role in health and disease.

Activation of the 5 lipoygenase (5LO) system within the vascular bed requires the presence of several cell types with distinct transcellular cross-talk mechanisms, resulting in the generation of 5LO produced metabolites and increased expression of receptors for these metabolites in vascular cells. The key products in this system, the leukotriens LTB4, LTC4 and LTD4, are potent mediators of vascular inflammation initiated by white blood cells and sustained or propagated thereafter through amplified metabolite generation and direct effects in endothelial and vascular smooth muscle cells. Leukotrienes act to enhance cell permeability and increase oxidative stress, vascular smooth muscle cell migration and arterial tone. 5LO activation is highly regulated, and is apparently both model/species-specific and region-specific. 5LO activation is also linked to plaque progression, plaque stability, activation of matrix metalloproteinases, propensity to coronary and cerebrovascular events and the evolution of aortic aneurysms. Genetic variants in the 5LO activating protein are strongly linked to increased cardiovascular risk and may serve as useful markers for future therapy targeting down regulation of 5LO expression and activity as a means to combat cardiovascular disease.

Arachidonate 5-Lipoxygenase↗

PubMed2005

Identification of cytoplasmic p53 protein in corneal epithelium of vertebrates.

The tumour suppressor gene p53 encodes a phosphoprotein involved in the control of cell growth. It's expression and function have been documented in malignancy, apoptosis and the aging processes. Recently, p53 expression has been demonstrated in normal murine tissues, including whole eye. Currently, we intend to map and to characterize p53 expression in the normal cornea across different species. To do this, eyes of animals were enucleated after sacrifice by CO(2) narcosis and then p53 expression in whole eyes (cornea) was mapped by indirect immunohistochemical staining techniques using the anti-p53 monoclonal antibodies PAb 248, PAb 421 and PAb 240 (alternatively called mAb 248, mAb 421 and mAb 240, respectively). Additionally, eyes were freshly dissected to separate the corneas, for quantitating p53 expression, using Western blot analysis. We found strong cytoplasmic p53 expression in the corneal epithelium of various vertebrate species by immunohistochemistry and by Western analysis. High levels of cytoplasmic p53 protein were normally found in normal corneal epithelium of various vertebrate species. Hence, these data may indicate that p53 may have a new evolutionary significant function in the eye.

Animals↗

PubMed2005

The peripheral-type benzodiazepine receptor and tumorigenicity: isoquinoline binding protein (IBP) antisense knockdown in the C6 glioma cell line.

Peripheral-type benzodiazepine receptors (PBR) are constituted by three protein components, the isoquinoline binding protein (IBP), the voltage-dependent anion channel (VDAC), and the adenine nucleotide transporter (ANT). Recently, we found that high levels of PBR ligand binding in glioma cell lines correlate with in vitro tumorigenicity. To study whether enhanced PBR expression is causative or in response to cancer, we genetically modified C6 glioma cells. Antisense knockdown of the IBP resulted in more than 50% reductions in PBR ligand binding both in the mitochondrial and whole cell fractions, accompanied by similar reductions in IBP levels in these respective fractions. The IBP knockdown was accompanied by a 25% increase in cell number in confluent cultures. This correlated with an 8-fold increase in in vitro tumorigenicity, as assessed by anchorage independent growth. Cell cycle analysis indicated that knockdown of the IBP resulted in a 60% reduction in the number of cells in the pre-G1 apoptosis phase. This paralleled the reduction seen in apoptosis and cell death shown by DNA fragmentation and Trypan blue assays, respectively. Furthermore, knockdown of the IBP appeared to prevent induction of apoptosis by the antineoplastic agent, erucylphosphocholine. In addition, IBP knockdown prevented processing of the caspase 3 component of the apoptosis cascade by the erucylphosphocholine congener, erucylphospho-N,N,N-trimethylammonium. In conclusion, our results suggest that enhanced IBP expression, including enhanced PBR ligand binding, such as occurring in untreated C6 glioma cells, may provide a mechanism to increase apoptotic rates of cancer cells.

Animals↗

PubMed2005

Angiotensin II increases the expression of lectin-like oxidized low-density lipoprotein receptor-1 in human vascular smooth muscle cells via a lipoxygenase-dependent pathway.

BACKGROUND: Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a membrane protein that can act as a surface endocytosis receptor for oxidized LDL (ox-LDL). As increased cellular uptake of ox-LDL by macrophages and activated smooth muscle cells may transform these cells into foam cells, potential interactions among LDL oxidation, ox-LDL uptake, and regulators of vascular smooth muscle cell function are of obvious interest. The objective of this study was to examine the effect of angiotensin II (AII) on the expression of LOX-1 and ox-LDL degradation in human vascular smooth muscle cells (VSMC) METHODS: We performed in vitro experiments in a human VSMC line (T/G HA-VSMC) derived from normal aortic VSMC, using standards methods. RESULTS: We found that AII (10(-7) mol/L) increased the expression of LOX-1 (approximately 2.5-fold, P < .0001) in association with higher degradation of ox-LDL by HA-SMC (from 4019 +/- 529 ng/mg cell protein to 6207 +/- 287 ng/mg cell protein; P = .0033). AII also increased the expression of 12-lipoxygenase (12-LO) and 15-lipoxygenase (15-LO) by approximately 2.2-fold (P = .03) and approximately 3-fold (P = .006), respectively. In addition, AII (10(-7) mol/L) increased the release of 12- and 15-hydroxyeicosatetraenoic acid from VSMC within 10 min approximately 3-fold (P = .03) and 50% (P < .05), respectively. CONCLUSIONS: Our study findings provide evidence that angiotensin II upregulates LOX-1 and 12-LO and 15-LO expression in human VSMC, thereby potentially providing mechanisms for both accelerated LDL oxidation within the cell and the internalization of exogenous ox-LDL, two processes that could increase the susceptibility of human VSMC to further transformation into foam cells.

Angiotensin II↗

PubMed2004

Peripheral benzodiazepine receptor antisense knockout increases tumorigenicity of MA-10 Leydig cells in vivo and in vitro.

Peripheral benzodiazepine receptors (PBR), first described more than 20 years ago, have been attributed with many putative functions including ones in cellular proliferation and cellular respiration. Hence, it is quite conceivable that deregulation of this receptor could lead to pathology. We and others have reported the existence of PBR overexpression in different human and nonhuman malignancies, but it has never been made clear whether this aberrant malignant PBR expression is a cause or consequence of the cancer. In the current study we induced PBR underexpression by downregulating one critical subunit of the PBR complex, the isoquinoline-binding protein (IBP), using the stable antisense knockout approach, in the MA-10 Leydig cell line. Resultant clones, showing PBR deregulation, also demonstrated increased tumorigenicity, using both in vitro (loss of contact inhibition and growth in soft agar) and in vivo (increased mortality on grafting back into isogenic mice) assays. We suggest that this type of deregulation could be a later event in natural tumor progression. Consequently, PBR deregulation should be more closely studied in human malignancy.

Animals↗

PubMed2004

Peripheral-type benzodiazepine receptor density and in vitro tumorigenicity of glioma cell lines.

The peripheral-type benzodiazepine receptor is found primarily on the outer mitochondrial membrane and consists of three subunits: the 18kDa isoquinoline binding protein, the 32kDa voltage-dependent anion channel, and the 30kDa adenine nucleotide transporter. The current study evaluates the potential importance of peripheral-type benzodiazepine receptor expression in glioma cell tumorigenicity. While previous studies have suggested that peripheral-type benzodiazepine receptor-binding may be relatively increased in tumor tissue and cells, so far, little is known about the relationships between peripheral-type benzodiazepine receptor density and factors underlying tumorigenicity. In the present study, we found in glioma cell lines (C6, U87MG, and T98G), that peripheral-type benzodiazepine receptor ligand-binding density is relatively high for C6 and low for T98G, while U87MG displays intermediate levels. Cell growth of these cell lines in soft agar indicated that high levels of peripheral-type benzodiazepine receptor-binding were associated with increased colony size, indicative of their ability to establish anchorage independent cell proliferation. Potential causes for differences in tumorigenicity between these cell lines were suggested by various cell death and proliferation assays. Cell death, including apoptosis, appeared to be low in C6, and high in T98G, while U87MG displayed intermediate levels in this respect. Cell proliferation appeared to be high in C6, low in T98G, and intermediate in U87MG. In conclusion, our study suggests that relatively high peripheral-type benzodiazepine receptor-binding density is associated with enhanced tumorigenicity and cell proliferation rate. In particular, apoptosis appears to be an important tumorigenic determinant in these glioma cell lines. Moreover, application of PBR-specific ligands indicated that PBR indeed are functionally involved in apoptosis in glioma cells.

Animals↗

PubMed2002

p53 expression in the normal murine eye.

PURPOSE: The tumor-suppressor gene p53 encodes a phosphoprotein involved in the control of cell growth. Its expression and function have been documented in malignancy, apoptosis, and other abnormal cell proliferation processes. Recently, expression of p53 has been demonstrated in certain normal tissues, including whole eye. The purpose of the study was to map and to characterize expression of p53 in the normal murine eye. METHODS: Eyes of adult C57BL/6 mice were enucleated after death by CO2 narcosis. Expression of p53 in frozen sections of whole cryoprotected eyes was mapped by indirect immunofluorescence microscopy using the anti-p53 monoclonal antibodies 248 and 421 and the polyclonal antibody FL-393. Additionally, eyes were freshly dissected to separate the various ocular tissues. In these ocular tissues, expression of p53 was quantitated with ELISA and Western blot analyses. RESULTS: Strong expression of p53 was observed in various normal ocular tissues. The corneal and conjunctival epithelium exhibited very high cytoplasmic p53 protein levels. High nuclear p53 protein staining was seen in the lens epithelial cells of the central and pre-equatorial zones and in the lens fiber nuclear bow, situated posterior to the epithelial germinative zone. Cells of the actual lens germinative zone did not stain for p53 protein. Low levels of p53 protein were expressed in retinal tissue. CONCLUSIONS: High levels of p53 protein are found in various normal murine ocular tissues, especially the corneal and conjunctival structures and the lens epithelium. Each of these tissues demonstrate unique patterns of staining.

Animals↗