Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Advanced glycation endproduct (AGE), whose formation is accelerated on long lived extracellular matrix proteins in diabetes, is implicated in diabetic complications in various tissues. Type I collagen is the predominant matrix protein of bone and plays an important role in bone cell-matrix interactions. We have previously reported the accelerated accumulation of AGE collagen in bone tissue in diabetes mellitus (DM), in which reduced bone mineral density was observed. In addition, when cultures of mature primary rat osteoblasts were plated onto an in vitro AGE-modified collagen substrate, they showed altered cell functions, in terms of alkaline phosphatase (ALP) activity, osteocalcin secretion, and nodule formation (J Bone Miner Res 11:931-937; 1996). To determine whether AGE collagen might also affect differentiation of preosteoblasts, we compared the effects of plating the preosteoblastic UMR 201-10B cell line onto AGE-modified collagen with plating onto unmodified collagen. The latter had been shown previously to promote differentiation of UMR 201 cells. We have also explored whether these effects might be partly mediated by the transforming growth factor beta (TGF-beta) receptor. Growth of UMR 201-10B cells on a type I collagen substrate significantly inhibited cell growth and retinoic acid (RA)-induced upregulation of ALP activity, compared to cells on plastic. These inhibitory effects were reduced by prior glycation of collagen, in a dose-dependent manner with respect to AGE content. Unmodified collagen stimulated production of osteopontin mRNA, which was reduced by AGE modification to levels attained in cells on plastic. Growth on control collagen inhibited TGF-beta type II receptor binding in 10B cells, while this inhibition was reduced by AGE modification. These data suggest that glycation of collagen interferes with specific interaction(s) between UMR 201-10B cells and collagen. Based on our previous results in UMR 201 cells, these results would be compatible with the notion that glycated collagen has reduced ability to promote differentiation of preosteoblasts to mature osteoblasts. These data further suggest that collagen-mediated events in these cells may be at least in part mediated by regulation of the TGF-beta receptor expression.
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PMID:Nonenzymatic glycation of type I collagen modifies interaction with UMR 201-10B preosteoblastic cells. 927 88

The high-Km glucose transporter, GLUT-2, and the high-Km hexokinase of beta cells, glucokinase (GK), are required for glucose-stimulated insulin secretion (GSIS). GLUT-2 expression in beta cells of Zucker diabetic fatty (ZDF) rats is profoundly reduced at the onset of beta-cell dysfunction of diabetes. Because ZDF rats are homozygous for a mutation in their leptin receptor (OB-R) gene and are therefore leptin-insensitive, we expressed the wild-type OB-R gene in diabetic islets by infusing a recombinant adenovirus (AdCMV-OB-Rb) to determine whether this reversed the abnormalities. Leptin induced a rise in phosphorylated STAT3, indicating that the transferred wild-type OB-R was functional. GLUT-2 protein rose 17-fold in AdCMV-OB-Rb-treated ZDF islets without leptin, and leptin caused no further rise. GK protein rose 7-fold without and 12-fold with leptin. Preproinsulin mRNA increased 64% without leptin and rose no further with leptin, but leptin was required to restore GSIS. Clofibrate and 9-cis-retinoic acid, the partner ligands for binding to peroxisome proliferator-activator receptor alpha (PPARalpha) and retinoid X receptor, up-regulated GLUT-2 expression in islets of normal rats, but not in ZDF rats, in which PPARalpha is very low. Because the fat content of islets of diabetic ZDF rats remains high unless they are treated with leptin, it appears that restoration of GSIS requires normalization of intracellular nutrient homeostasis, whereas up-regulation of GLUT-2 and GK is leptin-independent, requiring only high expression of OB-Rb.
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PMID:Overexpression of leptin receptors in pancreatic islets of Zucker diabetic fatty rats restores GLUT-2, glucokinase, and glucose-stimulated insulin secretion. 975 66

The existence of several different types of retinoid receptors, response elements, and cofactors means that retinoid physiology is mediated by multiple discrete pathways and is highly complex. As a result, non-selective retinoids have a multitude of physiologic effects and are usually associated with toxicity problems that limit their therapeutic usefulness. In contrast, because receptor-selective retinoids have a more focused and targeted action, they are likely to have a better therapeutic index. Tazarotene is the first of a new generation of receptor-selective retinoids. Its actions are targeted on 2 retinoic acid receptors (RARs), RAR-beta and RAR-gamma. Current retinoid research is leading to the development not only of many more novel receptor-selective retinoids but also of novel types of function-selective retinoids such as RAR inverse agonists and RAR antagonists. These retinoids are expected to be of clinical benefit not only in dermatology but also in oncology, diabetes, and diseases associated with the human papilloma virus.
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PMID:Future trends: a new generation of retinoids. 977 94

The recently cloned sodium-iodide symporter (NIS) represents a key molecule for thyroid function by efficiently accumulating iodide from the circulation into the thyrocyte against an electrochemical gradient. This uptake requires energy, is coupled to the action of Na+/K+-ATPase, and stimulated by TSH, the main hormone regulating thyroid-specific functions. NIS mutations are found in congenital hypothyroidism, and potential defects in the NIS gene, its expression, or function of the NIS protein are currently under investigation in various thyroid diseases. Increased NIS expression has been found in autonomous adenoma and Graves' disease, decreased levels of NIS protein and/or mRNA were observed in Hashimoto's disease, cold nodules, most thyroid cancers and cell lines derived therefrom. Autoantibodies directed against NIS have been identified in autoimmune thyroid disease and blocking antibodies isolated from sera of patients with Hashimoto's disease inhibit NIS function in NIS-transfected CHO cells. NIS mRNA expression can be up-regulated by retinoic acid in human thyroid carcinoma cell lines whereas retinoic acid treatment decreases NIS expression and function in differentiated rat thyroid FRTL-5 cells. Apart from thyrocytes, NIS is also expressed in other tissues known to transiently accumulate radioiodide, albeit at much lower levels, requiring RT-PCR for detection of the transcript. Diagnostic and therapeutic implications of the recent cloning of the human NIS gene such as development of NIS-directed drugs, ligands, antibodies, vaccines, gene therapeutic approaches combining NIS targeting and expression together with the long-established, efficient and safe method of radioiodide therapy are discussed both for application to thyroid related diseases and carcinoma, and non-thyroid benign and malignant diseases. Apart from these therapeutic and diagnostic perspectives the availability of the NIS gene will also open new opportunities to develop sensitive and homologous diagnostic test systems to identify factors involved in autoimmune thyroid disease, evolution of goitre, adenoma and thyroid cancer as well as NIS-directed new drugs. Advanced and sophisticated molecular diagnostic approaches (RT-PCR from fine needle aspirations, screening for mutations, analysis of gene defects) are already developed for NIS and will complement or overcome some established procedures in thyroid diagnostics.
Exp Clin Endocrinol Diabetes 1998
PMID:Implications of the molecular characterization of the sodium-iodide symporter (NIS). 986 44

The exposure of SY5Y neuroblastoma cells to high concentrations of glucose, fructose, or galactose is an experimental model commonly used for in vitro evaluation of typical neuronal alterations observed in diabetes mellitus. In the present study, we observed that 2 weeks of exposure to high carbohydrate concentrations caused both a significant impairment in neurite formation induced by supplementation of retinoic acid or by subtraction of fetal calf serum to the culture medium and a marked reduction in Na(+)-K(+)-ATPase activity. However, only the exposure to high millimoles of glucose caused an enhancement of mono-ADP-ribosylation, typical of diabetes mellitus, affecting at least five proteins. The concomitant exposure to high glucose and to silybin, a mono-ADP-ribosylation inhibitor, normalized the extent of ADP-ribosylation of the five proteins and counteracted the inhibitory effects of high glucose on Na(+)-pump activity and on neuritogenesis. Conversely, the supplementation of silybin did not prevent fructose and galactose inhibitory effects on Na(+)-pump activity and neurite formation. These data confirm those of previous reports suggesting a link between excessive protein mono-ADP-ribosylation and the onset of diabetic complications such as diabetic neuropathy.
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PMID:Inhibition of high glucose-induced protein mono-ADP-ribosylation restores neuritogenesis and sodium-pump activity in SY5Y neuroblastoma cells. 1046 90

Naturally occurring retinoids (vitamin A or retinol and its active metabolites) are vital for vision, controlling the differentiation program of epithelial cells in the digestive tract and respiratory system, skin, bone, the nervous system, the immune system, and for hematopoiesis. Retinoids are essential for growth, reproduction (conception and embryonic development), and resistance to and recovery from infection. The functions of retinoids in the embryo begin soon after conception and continue throughout the lifespan of all vertebrates. Both naturally occurring and synthetic retinoids are used in the therapy of various skin diseases, especially acne, for augmenting the treatment of diabetes, and as cancer chemopreventive agents. Retinol metabolites serve as ligands that activate specific transcription factors in the superfamily of steroid/retinoid/thyroid/vitamin D/orphan receptors and thereby control gene expression. Additionally, retinoids may also function through non-genomic actions. Various retinoid binding proteins serve as partners in retinoid function. These binding proteins show high specificity and affinity for specific retinoids and seem to control retinoid metabolism in vivo qualitatively and quantitatively by reducing 'free' retinoid concentrations, protecting retinoids from non-specific interactions, and chaperoning access of metabolic enzymes to retinoids. Implementation of the physiological effects of retinoids depends on the spatial-temporal expressions of binding proteins, receptors and metabolic enzymes. This review will discuss current understanding of the enzymes that catalyze retinol and retinoic acid metabolism and their unique and integral relationship to retinoid binding proteins.
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PMID:Interactions of retinoid binding proteins and enzymes in retinoid metabolism. 1052 99

Retinoids mediate a number of physiological pathways through their effects on cellular growth and differentiation. Upon binding to retinoic acid receptors (RARs) and retinoid X receptors (RXRs), retinoids regulate cellular processes by directly modulating the expression of responsive genes. The wide-ranging effects of retinoid action are attributable to two main factors-the ubiquitous distribution of several subtypes and isoforms of RARs and RXRs, and the ability of these receptors to regulate numerous genes upon ligand activation. The broad range of effects mediated by retinoids means not only that they have many potential therapeutic applications but also that non-selective retinoids are associated with a high incidence of adverse effects. The design of retinoids that are receptor-selective and function-selective is a strategy that is proving successful in developing novel retinoids that offer not only good efficacy but also good tolerability. Tazarotene, a receptor-selective retinoid indicated for the topical treatment of psoriasis, is at the forefront of this new generation of retinoids. In the near future, other receptor-selective retinoids may prove useful for the treatment of other dermatological diseases, cancer, and diabetes.
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PMID:Novel retinoids with receptor selectivity and functional selectivity. 1073 Nov 29

Natural (all trans-retinoic acid, RA) and synthetic retinoids exhibit potent anti-proliferative, normalization of differentiation and anti-inflammatory activities which appear to account for their therapeutic effects in acne, psoriasis, photoaging, precancerous lesions and established cancers. Although RA has shown considerable promise in dermatologic indications, certain side effects have restricted its use as a choice of agent for chronic administration. Systematic synthesis of receptor-selective retinoids has resulted in two topical drugs, Tazorac/Zorac (tazarotene) and Differin (adapalene). Tazorac is indicated for psoriasis and acne and Differin gel for the treatment of acne. These drugs bind to the retinoic acid receptor (RAR) family members. Various RAR subtype-specific and function-selective retinoids have been synthesized. These retinoids, which are in various stages of pre-clinical development for the treatment of cancers, psoriasis and as an antidote to Accutane-mediated mucocutaneous toxicity, will also be discussed in this review. Discovery of another retinoid receptor, retinoid X receptor (RXR), revealed that RXR-specific retinoids already existed in retinoid chemical libraries. Structure activity relationship studies based upon binding and transactivation assays led to the synthesis of RXR-specific ligands with high affinities for RXR subtypes. These compounds were found to be effective in the treatment of hyperglycemia in animal models of type II diabetes. The discovery of novel retinoids along with an increased understanding of the biological functions and mechanisms of action of retinoid receptors are likely to result in improved treatments for existing responsive indications and identification of new retinoid therapeutic targets.
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PMID:Recent developments in receptor-selective retinoids. 1082 16

We identified the peroxisomal proliferator response element (PPRE) in the +68/+89 region of the rat GLUT2 gene. To identify whether the putative PPRE in the GLUT2 gene (GLUT2-PPRE) is functional, GLUT2 promoter-luciferase reporter constructs were transfected into CV-1 cells. Promoter activities were increased by coexpression of peroxisomal proliferator-activated receptor (PPAR)-gamma, retinoid X receptor (RXR)-alpha, and treatment of their ligands; troglitazone and 9-cis retinoic acid potentiated the transactivational effects. Introduction of mutations in GLUT2-PPRE resulted in loss of transactivational effects of the PPAR-gamma/RXR-alpha heterodimer. Electrophoretic mobility shift assay using nuclear extracts of CV-1 cells, which were transfected with various combinations of PPARs or RXR-alpha expression plasmids, revealed that heterodimers of PPAR-gamma and RXR-alpha preferentially bound to GLUT2-PPRE. In HIT-T15 cells, promoter activity of the rat GLUT2 gene was increased by troglitazone and 9-cis retinoic acid, and mutations of GLUT2-PPRE resulted in reduction of promoter activity. In addition, we observed increased GLUT2 transcription by troglitazone and 9-cis retinoic acid in isolated rat primary islets. These results suggested that the GLUT2-PPRE is functional and plays a significant role in gene expression of GLUT2 in pancreatic beta-cells. This is the first report identifying PPRE in a gene involved in glucose homeostasis, linking the effect of troglitazone on the regulation of insulin secretion.
Diabetes 2000 Sep
PMID:Identification and functional characterization of the peroxisomal proliferator response element in rat GLUT2 promoter. 1096 36

Cancer is a common life-threatening disease. Prevention and therapy of the disease are the desire of everybody. This paper summarizes our attempt to the tough challenge. Chronologically we began the study of carcinogenesis, and then turned to the research of anticancer agents. Identification of food mutagens was extensively studied. Once they were identified, the mechanism of nucleic acid modifications by these mutagens had been studied. The modification study gave information on the nucleic acid modification by mitomycin and bleomycin. The structure-activity relationship study of phorbol esters and teleocidines whose tumor promotion is epigenetic, was extensively studied. On the other hand, retinoic acid, a vitamin A metabolite, suppresses the epigenetic tumor promotion. This suggests that an epigenetically active compound rather than a cytotoxic anticancer agent can be used for tumor suppression. In the retinoid research, we found a number of characteristic new active substances which may be of therapeutic use: some of them are in the clinical trial stages in the field of dermatology and cancer. During the chemical study of retinoids, we encountered the retinoic acid receptor, coded by the retinoic acid receptor (RAR) gene which had just reported. Further retinoid research yielded retinoids antagonists, and then RXR(retinoic acid-X-receptor)-agonists and RXR-antagonists. These ligands have a big potential in the therapy of diabetes and obesity.
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PMID:[From cancer prevention to cancer treatment]. 1108 9


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