University of Texas Southwestern Medical Center

About: University of Texas Southwestern Medical Center is a healthcare organization based out in Dallas, Texas, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 39107 authors who have published 75242 publications receiving 4497256 citations. The organization is also known as: UT Southwestern & UT Southwestern Medical School.

Hypoxia-inducible factor 1α induces fibrosis and insulin resistance in white adipose tissue

Abstract: Adipose tissue can undergo rapid expansion during times of excess caloric intake. Like a rapidly expanding tumor mass, obese adipose tissue becomes hypoxic due to the inability of the vasculature to keep pace with tissue growth. Consequently, during the early stages of obesity, hypoxic conditions cause an increase in the level of hypoxia-inducible factor 1alpha (HIF1alpha) expression. Using a transgenic model of overexpression of a constitutively active form of HIF1alpha, we determined that HIF1alpha fails to induce the expected proangiogenic response. In contrast, we observed that HIF1alpha initiates adipose tissue fibrosis, with an associated increase in local inflammation. "Trichrome- and picrosirius red-positive streaks," enriched in fibrillar collagens, are a hallmark of adipose tissue suffering from the early stages of hypoxia-induced fibrosis. Lysyl oxidase (LOX) is a transcriptional target of HIF1alpha and acts by cross-linking collagen I and III to form the fibrillar collagen fibers. Inhibition of LOX activity by beta-aminoproprionitrile treatment results in a significant improvement in several metabolic parameters and further reduces local adipose tissue inflammation. Collectively, our observations are consistent with a model in which adipose tissue hypoxia serves as an early upstream initiator for adipose tissue dysfunction by inducing a local state of fibrosis.

Binding of neuroligins to PSD-95

Abstract: PSD-95 is a component of postsynaptic densities in central synapses. It contains three PDZ domains that localizeN-methyl-d-aspartate receptor subunit 2 (NMDA2 receptor) and K+ channels to synapses. In mouse forebrain, PSD-95 bound to the cytoplasmic COOH-termini of neuroligins, which are neuronal cell adhesion molecules that interact with β-neurexins and form intercellular junctions. Neuroligins bind to the third PDZ domain of PSD-95, whereas NMDA2 receptors and K+ channels interact with the first and second PDZ domains. Thus different PDZ domains of PSD-95 are specialized for distinct functions. PSD-95 may recruit ion channels and neurotransmitter receptors to intercellular junctions formed between neurons by neuroligins and β-neurexins.

A detergent-free method for purifying caveolae membrane from tissue culture cells.

Abstract: Current methods for purifying caveolae from tissue culture cells take advantage of the Triton X-100 insolubility of this membrane domain. To circumvent the use of detergents, we have developed a method that depends upon the unique buoyant density of caveolae membrane. The caveolae fractions that we obtain are highly enriched in caveolin. As a consequence we are able to identify caveolae-associated proteins that had previously gone undetected. Moreover, resident caveolae proteins that are soluble in Triton X-100 are retained during the isolation.

Massive xanthomatosis and atherosclerosis in cholesterol-fed low density lipoprotein receptor-negative mice.

Abstract: Mice that are homozygous for a targeted disruption of the LDL receptor gene (LDLR-/- mice) were fed a diet that contained 1.25% cholesterol, 7.5% cocoa butter, 7.5% casein, and 0.5% cholic acid. The total plasma cholesterol rose from 246 to > 1,500 mg/dl, associated with a marked increase in VLDL, intermediate density lipoproteins (IDL), and LDL cholesterol, and a decrease in HDL cholesterol. In wild type littermates fed the same diet, the total plasma cholesterol remained < 160 mg/dl. After 7 mo, the LDLR-/- mice developed massive xanthomatous infiltration of the skin and subcutaneous tissue. The aorta and coronary ostia exhibited gross atheromata, and the aortic valve leaflets were thickened by cholesterol-laden macrophages. No such changes were seen in the LDLR-/- mice on a normal chow diet, nor in wild type mice that were fed either a chow diet or the high-fat diet. We conclude that LDL receptors are largely responsible for the resistance of wild type mice to atherosclerosis. The cholesterol-fed LDLR-/- mice offer a new model for the study of environmental and genetic factors that modify the processes of atherosclerosis and xanthomatosis.