BackgroundObesity induced by high fat (HF) diet is associated with inflammation which contributes to development of insulin resistance. Most prior studies have focused on adipose tissue as the source of obesity-associated inflammation. Increasing evidence links intestinal bacteria to development of diet-induced obesity (DIO). This study tested the hypothesis that HF western diet and gut bacteria interact to promote intestinal inflammation, which contributes to the progression of obesity and insulin resistance.Methodology/Principal FindingsConventionally raised specific-pathogen free (CONV) and germ-free (GF) mice were given HF or low fat (LF) diet for 2–16 weeks. Body weight and adiposity were measured. Intestinal inflammation was assessed by evaluation of TNF-α mRNA and activation of a NF-κBEGFP reporter gene. In CONV but not GF mice, HF diet induced increases in body weight and adiposity. HF diet induced ileal TNF-α mRNA in CONV but not GF mice and this increase preceded obesity and strongly and significantly correlated with diet induced weight gain, adiposity, plasma insulin and glucose. In CONV mice HF diet also resulted in activation of NF-κBEGFP in epithelial cells, immune cells and endothelial cells of small intestine. Further experiments demonstrated that fecal slurries from CONV mice fed HF diet are sufficient to activate NF-κBEGFP in GF NF-κBEGFP mice.Conclusions/SignificanceBacteria and HF diet interact to promote proinflammatory changes in the small intestine, which precede weight gain and obesity and show strong and significant associations with progression of obesity and development of insulin resistance. To our knowledge, this is the first evidence that intestinal inflammation is an early consequence of HF diet which may contribute to obesity and associated insulin resistance. Interventions which limit intestinal inflammation induced by HF diet and bacteria may protect against obesity and insulin resistance.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the initial and rate-limiting step of glycerolipid synthesis. Two distinct GPAT isoenzymes had been identified in mammalian tissues, an N-ethylmaleimide (NEM)-sensitive isoform in the endoplasmic reticulum membrane (microsomal GPAT) and an NEM-resistant form in the outer mitochondrial membrane (mtGPAT). Although only mtGPAT has been cloned, the microsomal and mitochondrial GPAT isoforms can be distinguished, because they differ in acyl-CoA substrate preference, sensitivity to inhibition by dihydroxyacetone phosphate and polymixin B, temperature sensitivity, and ability to be activated by acetone. The preponderance of evidence supports a role for mtGPAT in synthesizing the precursors for triacylglycerol synthesis. In mtGPAT ؊/؊ mice, PCR genotyping and Northern analysis showed successful knockout of mtGPAT; however, we detected a novel NEM-sensitive GPAT activity in mitochondrial fractions and an anti-mtGPAT immunoreactive protein in liver mitochondria, but not in microsomes. Rigorous analysis using two-dimensional gel electrophoresis revealed that the anti-mtGPAT immunoreactive proteins in wild type and mtGPAT ؊/؊ liver mitochondria have different isoelectric points. These results suggested the presence of a second GPAT in liver mitochondria from mtGPAT ؊/؊ mice. Characterization of this GPAT activity in liver from mtGPAT null mice showed that, unlike the mtG-PAT activity in wild type samples, activity in mtGPAT knockout mitochondria did not prefer palmitoyl-CoA, was sensitive to inactivation by NEM, was inhibited by dihydroxyacetone phosphate and polymixin B, was temperature-sensitive, and was not activated by acetone. We conclude that a novel GPAT (mtGPAT2) with antigenic epitopes similar to those of mtGPAT is detectable in mitochondria from the livers of mtGPAT ؊/؊ mice.The initial and rate-limiting step of glycerolipid synthesis is the acylation of glycerol 3-phosphate with long-chain fatty acylCoA to form 1-acyl-glycerol 3-phosphate (LPA). 1 This reaction is catalyzed by two glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15) isoenzymes that are encoded by different genes (1). One isoform is present in the endoplasmic reticulum membrane (microsomal GPAT), and the other is located in the outer mitochondrial membrane (mtGPAT). Although the microsomal GPAT has not been cloned or purified, its activity is easily distinguished, because, unlike mtGPAT, the microsomal isoform is inhibited by sulfhydryl reagents (2). In most tissues, the microsomal GPAT activity is 10 times higher than that found in the mitochondrial fraction, but in liver, mtGPAT contributes 30 -50% of the total activity (1).Microsomal GPAT and mtGPAT also differ in their acyl-CoA substrate preference. The microsomal isoform esterifies both saturated and unsaturated long-chain acyl-CoAs equally well, but mtGPAT prefers C16:0-CoA (2). In rat liver, kidney, and heart, mtGPAT activity is 3-10-fold higher with C16:0-CoA than with other long-chain saturated or unsaturated acyl-CoA substrates (3...

There is an urgent need for new therapeutics for the treatment of aggressive and metastatic refractory human non-small-cell lung cancer (NSCLC). Antiangiogenesis therapy and chemotherapy are the two major treatment options. Unfortunately, both types of therapies when used individually have their disadvantages. Integrating antiangiogenesis therapy with chemotherapy is expected to target the tumor's vascular endothelial cells and the tumor cells simultaneously. In this study, we coformulated Vascular endothelial growth factor (VEGF) siRNA targeting VEGFs and gemcitabine monophosphate (GMP) into a single cell-specific, targeted lipid/calcium/phosphate (LCP) nanoparticle formulation. Antitumor effect of the combination therapy using LCP loaded with both VEGF siRNA and GMP was evaluated in both subcutaneous and orthotopic xenograft models of NSCLC with systemic administration. The improved therapeutic response, as compared with either VEGF siRNA or GMP therapy alone, was supported by the observation of 30-40% induction of tumor cell apoptosis, eightfold reduction of tumor cell proliferation and significant decrease of tumor microvessel density (MVD). The combination therapy led to dramatic inhibition of tumor growth, with little in vivo toxicity. In addition, the current studies demonstrated the possibility of incorporating multiple nucleic acid molecules and phosphorylated small-molecule drugs, targeting to different pathways, into a single nanoparticle formulation for profound therapeutic effect.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the initial and rate-limiting step in glycerolipid synthesis. Several mammalian GPAT activities have been recognized, including Nethylmaleimide (NEM)-sensitive isoforms in microsomes and mitochondria and an NEM-resistant form in mitochondrial outer membrane (GPAT1). We have now cloned a second mitochondrial isoform, GPAT2 from mouse testis. The open reading frame encodes a protein of 798 amino acids with a calculated mass of 88.8 kDa and 27% amino acid identity to GPAT1. Testis mRNA expression was 50-fold higher than in liver or brown adipose tissue, but the specific activity of NEM-sensitive GPAT in testis mitochondria was similar to that in liver. When Cos-7 cells were transiently transfected with GPAT2, NEM-sensitive GPAT activity increased 30%. Confocal microscopy confirmed a mitochondrial location. Incubation of GPAT2-transfected Cos-7 cells with trace (3 μM; 0.25μCi) [1-14 C]oleate for 6 h increased incorporation of [ 14 C]oleate into TAG 84%. In contrast, incorporation into phospholipid species was lower than in control cells. Although a polyclonal antibody raised against full-length GPAT1 detected an ∼89 kDa band in liver and testis from GPAT1 null mice and both 89 and 80 kDa bands in BAT from the knockout animals, the GPAT2 protein expressed in Cos-7 cells was only 80 kDa. In vitro translation showed a single product of 89 kDa. Unlike GPAT1, GPAT2 mRNA abundance in liver was not altered by fasting or refeeding. GPAT2 is likely to have a specialized function in testis.The synthesis of triacylglycerol and all glycerophospholipids begins with the acylation of glycerol-3-phosphate with long-chain fatty acyl-CoA to produce 1-acylglycerol-3-phosphate. This reaction is catalyzed by glycerol-3-phosphate acyltransferase (GPAT 1 ; EC 3.1.3.9) which exhibits the lowest specific activity of all enzymes in the glycerol-3-phosphate pathway, suggesting that it is the rate limiting step [1].Three mammalian GPAT activities have been differentiated based on their subcellular location and biochemical properties [2,3]. GPAT activity is present in microsomal and mitochondrial Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. fractions. In most tissues, 90% of the activity is attributed to a microsomal GPAT which is sensitive to inactivation by sulfhydryl reagents such as NEM. Microsomal GPAT3, prominent in adipose tissue, has been cloned [4]. Microsomal GPAT activity does not appear to be regulated in liver. In contrast, the mitochondrial isoform (GPAT1) 2 that has been purified [5] and cloned [6,7], is highly regulated by i...

The remodeling of maternal uterine spiral arteries (SAs) is an essential process for ensuring low-resistance, high-capacitance blood flow to the growing fetus. Failure of SAs to remodel is causally associated with preeclampsia, a common and life-threatening complication of pregnancy that is harmful to both mother and fetus. Here, using both loss-of-function and gain-of-function genetic mouse models, we show that expression of the pregnancy-related peptide adrenomedullin (AM) by fetal trophoblast cells is necessary and sufficient to promote appropriate recruitment and activation of maternal uterine NK (uNK) cells to the placenta and ultimately facilitate remodeling of maternal SAs. Placentas that lacked either AM or its receptor exhibited reduced fetal vessel branching in the labyrinth, failed SA remodeling and reendothelialization, and markedly reduced numbers of maternal uNK cells. In contrast, overexpression of AM caused a reversal of these phenotypes with a concomitant increase in uNK cell content in vivo. Moreover, AM dose-dependently stimulated the secretion of numerous chemokines, cytokines, and MMPs from uNK cells, which in turn induced VSMC apoptosis. These data identify an essential function for fetal-derived factors in the maternal vascular adaptation to pregnancy and underscore the importance of exploring AM as a biomarker and therapeutic agent for preeclampsia.