Apo E, a key regulator of cholesterol-rich lipoprotein metabolism, is synthesized by numerous extrahepatic tissues. Although its synthesis in macrophages is documented, the contribution of macrophage-derived apo E to hepatic clearance of serum cholesterol is unknown. To address this issue bone marrow transplantation was performed on hypercholesterolemic apo E-deficient mice with either syngeneic apo Edeficient mouse bone marrow cells (EO-control) or wildtype mouse bone marrow cells expressing apo E (EOtreated). EO-control and EO-treated mice were fed either a regular chow diet or an atherogenic diet (designated EOcontrol-HF and EO-treated-HF). Serum cholesterol levels dropped dramatically in the EO-treated mice largely due to a reduction in their VLDL cholesterol. No changes were seen in the EO-control mice. After 4 wk serum cholesterol in EO-treated-HF mice was about four-fold lower compared to EO-control-HF animals. Moreover, the extent of atherosclerosis in the EO-treated-HF mice after 14-16 wk was greatly reduced. Wild-type apo E mRNA was detected in the liver, spleen, and brain of the EO-treated mice indicating that apo E gene transfer was successfully achieved through bone marrow transplantation. More importantly, the level of apo E expression was sufficient to reduce the severe hypercholesterolemia of the apo E-deficient mice fed either chow or atherogenic diets. (J. Clin. Invest. 1995. 96:1118-1124
The aim of this study was to determine the impact of ischemia on gene and protein expression profiles of healthy and malignant colon tissue and, thus, on screening studies for identification of molecular targets and diagnostic molecular patterns. Healthy and malignant colon tissue were snap-frozen at various time points (3-30 min) after colon resection. Gene and protein expression were determined by microarray (HG-U133A chips) and surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) technology (CM10 chips, SAX2 chips, and IMAC3Ni chips), respectively. Real-time reverse transcription PCR (RT-PCR) was used for comparative measurement of expression of particular genes. Initial changes of gene and protein expression profiles were already observed 5-8 min after colon resection. Fifteen minutes after surgery, 10%-15% of molecules, and after 30 min, 20% of all detectable genes and proteins, respectively, differed significantly from the baseline values. Significant changes of expression were found in most functional groups. As confirmed by real-time RT-PCR, this included not only known hypoxia-related molecules (HIF-1 alpha, c-fos, HO-1) but also cytoskeletal genes (e.g., CK20) and tumor-associated antigens (e.g., CEA). In conclusion, preanalytical factors, such as tissue ischemia time, dramatically affect molecular data. Control of these variables is mandatory to obtain reliable data in screening programs for molecular targets and diagnostic molecular patterns.
Bone marrow-derived macrophages and lymphocytes express LDL receptors (LDL-R), which allow these cells to take up cholesterol-rich lipoproteins. Although these cells are ubiquitously distributed in the body, it is not known whether they influence plasma cholesterol. Macrophages and T lymphocytes also are found in atherosclerotic lesions, but it is not known whether their LDL-R expression plays a role in atherosclerosis. To address these questions, we subjected LDL-R -/-mice to total body irradiation to eliminate their endogenous bone marrow-derived cells and repopulated them with either LDL-R-expressing wild-type bone marrow (treated mice) or LDL-R -/- bone marrow (control mice). Thus, the only difference between the two groups of mice was the ability of the bone marrow-derived cells to express the LDL-R in the treated mice. Plasma cholesterol levels were similar in the two groups of mice at 8 and 16 weeks after transplantation. Chromatographic separation of the lipoproteins revealed similar lipoprotein cholesterol distributions. Although the extent of lesion area in the aortic valves of the high-fat-diet-fed mice was more severe than that in the chow-fed mice, lesions appeared similar between control and treated mice given either chow or high-fat diet. Abundant LDL-R expression was detected in the lesions of treated mice, whereas the lesions of control mice showed no LDL-R expression, indicating that donor-derived leukocytes had migrated into the lesions of the recipient mice. Thus, bone marrow transplantation can be used as a tool to replace the endogenous bone marrow-derived cells in the artery wall with those of the donor origin.
Functional characterization of Na(+)-D-glucose cotransport in intestine and kidney indicates the existence of heterogeneous Na(+)-D-glucose cotransport systems. Target size analysis of the transporting unit and model analysis of substrate binding have been performed and proteins have been cloned which mediate (SGLT1) and modulate (RS1) the expression of Na(+)-D-glucose cotransport. The experiments support the hypothesis that functional Na(+)-D-glucose cotransport systems in mammals are composed of two SGLT1-type subunits and may contain one or two RS1-type proteins. SGLT1 contains up to twelve membrane-spanning alpha-helices, whereas RS1 is a hydrophilic extracellular protein which is anchored in the brush-border membrane by a hydrophobic alpha-helix at the C-terminus. SGLT1 alone is able to translocate glucose together with sodium; however, RS1 increases the Vmax of transport expressed by SGLT1. In addition, the biphasic glucose dependence of transport, which is typical for kidney and has been often observed in intestine, was only obtained after coexpression of SGLT1 and RS1.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.