Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied a 15-year-old girl (P1) suffering from the Hutchinson-Gilford syndrome (progeria) associated with a severe insulin resistance. Insulin binding activity to P1 erythrocytes was 85% reduced when compared to that measured in ten normal controls matched for sex and age. This finding was confirmed in Epstein-Barr virus (EBV)-transformed lymphoblasts and depends on a reduction in insulin receptor number. Also the amount of total insulin receptors, [35S]methionine labeled and immunoprecipitated, was 90% reduced in P1 lymphoblasts when compared to controls. Next, we measured insulin receptor mRNA levels and we found undetectable levels of insulin receptor transcript in P1 EBV-transformed lymphoblasts, in the absence of any rearrangement of insulin receptor gene as evaluated by Southern blot analysis. The marked reduction in insulin receptor gene expression probably accounts for the severe insulin resistance presented by the patient. Despite extensive studies, the molecular basis of progeria is still unknown. The near complete absence of a molecule crucial in the transduction of cell growth and differentiation signals could be involved in the accelerated aging of the patient.
Mol Cell Endocrinol 1991 Jan
PMID:Insulin receptor gene expression is reduced in cells from a progeric patient. 164 40

To investigate whether overexpression of the insulin receptor results in altered cell growth we used NIH 3T3 cells transfected with a bovine papilloma virus/insulin receptor cDNA construct (3T3/HIR). These cells expressed high numbers of insulin receptors (mean +/- sd, 631.0 +/- 16.7 ng receptors/10(6) cells). Insulin significantly stimulated the growth of 3T3/HIR cells maintained in serum-free medium. Moreover, in these cells, insulin induced marked phenotypic changes, including alterations in cell shape, loss of contact inhibition, and focal growth. In contrast to 3T3/HIR cells, insulin was without effect in either wild-type 3T3 cells (3T3/wt), 3T3 cells transfected with the neomycin resistance gene (3T3/NEO), or the bovine papilloma virus (3T3/BPV). To assess the presence of anchorage-independent growth, cells were seeded in soft agar and inspected for colony formation. 3T3/HIR cells showed absent or minimal colony growth in the absence of insulin. However, there was a dose-dependent insulin-stimulated increase in both colony size and number. Insulin-stimulated colony formation was specifically inhibited by an insulin antagonist, monoclonal antibody MA-10. In the presence of 100 nM insulin, about 3% of cells formed large colonies. Insulin neither stimulated growth nor induced colony formation in 3T3/wt cells or 3T3/NEO cells. Insulin also stimulated colony formation in CHO cells transfected with an insulin receptor cDNA construct. In conclusion, overexpression of normal insulin receptors induces a ligand-dependent transformed phenotype. This phenomenon may have clinical relevance by conferring a selective growth advantage to tumor cells with high numbers of insulin receptors.
Mol Endocrinol 1991 Mar
PMID:Overexpression of insulin receptors in fibroblast and ovary cells induces a ligand-mediated transformed phenotype. 165 97

The (Ca2+ + Mg2+) ATPase which serves as a Ca2+ pump in the kidney basolateral membranes is essential to the maintenance of an intracellular Ca2+ concentration optimal for kidney function. Since atrial natriuretic peptide (ANP) is known to participate in the Ca2+ homeostasis mechanism, altered levels of ANP in diabetes may vary the pump activity and consequently the kidney function. In order to examine the modulatory role of ANP on (Ca2+ + Mg2+) ATPase in short- (6 weeks) and long-term (6 months) diabetes, rats were injected with streptozotocin (65 mg/kg body wt, i.v.). At 6 weeks, the plasma ANP was decreased whereas, ANP-receptor binding in the kidney basolateral membrane was increased. In contrast, there was an increased plasma ANP and decreased ANP receptor binding at 6 months. Insulin treatment to diabetic animals normalized these parameters. The (Ca2+ + Mg2+) ATPase activity was unchanged both at 6 weeks and 6 months. Our results demonstrate that the unchanged Ca2+ pump activity in short-term and long-term diabetes serves to maintain the Ca2+ homeostasis in the kidney cells and thus may maintain the hyperfiltration state in diabetes. Unaltered (Ca2+ + Mg2+) ATPase is achieved by the initial up-regulation and subsequent down-regulation of the ANP receptors.
Mol Cell Biochem 1991 Jun 26
PMID:(Ca2+ + Mg2+) ATPase activity in kidney basolateral membrane in diabetes: role of atrial natriuretic peptide. 165

Insulin induces a rapid activation of p21ras in NIH 3T3 and Chinese hamster ovary cells that overexpress the insulin receptor. Previously, we suggested that p21ras may mediate insulin-induced gene expression. To test such a function of p21ras more directly, we studied the effect of different dominant inhibitory mutants of p21ras on the induction of gene expression in response to insulin. We transfected a collagenase promoter-chloramphenicol acetyltransferase (CAT) gene or a fos promoter-luciferase gene into NIH 3T3 cells that overexpressed the insulin receptor. The activities of both promoters were strongly induced after treatment with insulin. This induction could be suppressed by cotransfection of two inhibitory mutant ras genes, H-ras(Asn-17) or H-ras(Leu-61,Ser-186). In particular, insulin-induced activation of the fos promoter was inhibited completely by H-ras(Asn-17). These results show that p21ras functions as an intermediate in the insulin signal transduction route leading to the induction of gene expression.
Mol Cell Biol 1991 Dec
PMID:Two dominant inhibitory mutants of p21ras interfere with insulin-induced gene expression. 165 21

Oxytocin is produced in the granulosa-derived cells of the ruminant corpus luteum where its gene is dramatically up-regulated within days of ovulation. Regulation of these processes is poorly understood but oxytocin release can be increased by insulin, insulin-like growth factor I (IGF-I), and gonadotropins. Here we have assessed interactions between these regulatory systems. Follicle-stimulating hormone (FSH), luteinizing hormone (LH) and human chorionic gonadotropin (hCG) caused dose-dependent release of oxytocin from bovine granulosa cells cultured in medium containing 100 ng/ml insulin. The gonadotropins also increased oxytocin mRNA levels and their effects were mimicked by forskolin. The effects of these stimuli on oxytocin and progesterone release were synergistically increased by insulin or IGF-I. Binding studies revealed separate binding sites with characteristics of insulin and IGF-I receptors. Insulin potentiated the effects of hCG and forskolin on oxytocin mRNA levels and release of oxytocin and progesterone in cells from follicles containing greater than 50 ng/ml estradiol. In cells from follicles containing less than 5 ng/ml estradiol these stimuli had little effect on oxytocin release although progesterone release was synergistically increased by insulin and forskolin. The data suggest that gonadotropins regulate oxytocin synthesis and release and that these effects are amplified by insulin or IGF-I acting via their own receptors. Changes associated with maturation of the target cells in vitro appear prerequisite for oxytocin production in response to increased cAMP levels in the presence of insulin or IGF-I.
Mol Cell Endocrinol 1991 Jul
PMID:Effects of gonadotropins, insulin and insulin-like growth factor I on ovarian oxytocin and progesterone production. 166 78

Insulin-like growth factor-II (IGF-II), the predominant form of IGF in fetal and neonatal serum and tissues, is found in vivo complexed with IGF-binding proteins. One of these binding proteins, IGFBP-2, is present at high levels in fetal rat plasma and binds both IGF-I and IGF-II with high affinity. We here have used in situ hybridization to compare the distribution of IGFBP-2 mRNA with that of IGF-II mRNA in embryonic day 13.5-15 rat embryos. The spatial patterns of IGF-II and IGFBP-2 expression in the fetal trunk were distinct and, in general, nonoverlapping. Most mesoderm derivatives that express IGF-II at high levels contained little, if any, IGFBP-2 mRNA. Instead, IGFBP-2 mRNA was expressed at high levels in many cell types derived from ectoderm and endoderm. The expression of IGFBP-2 mRNA in the central nervous system (CNS) during this developmental period was examined in particular detail. The three most prominent sites of IGFBP-2 expression in the CNS were comprised of cells with nonneuronal phenotypes: 1) the epithelium of the choroid plexus, a tissue that produces cerebrospinal fluid; 2) the floor plate, an area that can guide axonal outgrowth from commissural neurons of the spinal cord in vitro; and 3) the infundibulum, the progenitor of the posterior pituitary that is believed to influence differentiation of the adjacent intermediate pituitary.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1990 Aug
PMID:The expression pattern of an insulin-like growth factor (IGF)-binding protein gene is distinct from IGF-II in the midgestational rat embryo. 170 58

We have characterized the role of tyrosine phosphorylation in protooncogene induction mediated by insulin-like growth factors I and II (IGF-I and IGF-II) in the Madin-Darby canine kidney (MDCK) cell line. These cells possess few, if any, insulin receptors, thus allowing determination of the effects of these growth factors in the absence of any secondary signal mediated through the insulin receptor. We found that IGF-I produced a specific stimulation of tyrosine kinase activity of the 97-kDa beta-subunit of the IGF-I receptor, resulting in autophosphorylation of the receptor and an increase in kinase activity toward a synthetic peptide substrate. This was associated with a gradual decrease in the level of phosphorylation of pp120, the major constitutive phosphotyrosine-containing protein of MDCK cells, and an increase in the ratio of serine to tyrosine phosphorylation. This was followed by a rapid, but transient, induction of c-fos gene expression, with no change in the levels of c-myc mRNA. Cycloheximide treatment resulted in a superinduction of both c-fos and c-myc and prevented any further stimulation by IGF-I. IGF-II did not stimulate tyrosine phosphorylation of its own receptor, but was 25% as active as IGF-I in stimulating phosphorylation of the IGF-I receptor. Despite this, IGF-II did not significantly enhance the expression of either nuclear protooncogene. Insulin also produced a delayed stimulation of IGF-I receptor phosphorylation, but was unable to stimulate biological effects in these cells. Under these conditions neither of the IGFs nor insulin produced any significant stimulation of thymidine incorporation into DNA. These data indicate that the IGF-I receptor can be activated upon binding of IGF-I, and to a lesser extent IGF-II, in intact cells to mediate cellular events. The nature of the signal generated by the IGF-I receptor appears to vary depending on the ligand that occupies it.
Mol Endocrinol 1991 Jan
PMID:Insulin-like growth factor-mediated phosphorylation and protooncogene induction in Madin-Darby canine kidney cells. 170 99

Insulin-like growth factors (IGFs) together with their binding proteins (BPs) are potential regulators of folliculogenesis in mammalian ovary. To identify the various species of IGFBPs present in the ovary, we have undertaken a comprehensive purification scheme using gel filtration, ligand-affinity chromatography, and several steps of reverse phase HPLC to isolate all of the BPs in pig ovarian follicular fluid. Our effort yielded five distinct IGFBPs, and upon analysis, they were found to correspond to the previously identified human and rat IGFBP-2, -3, -4, -5, and -6. IGFBP-1 was not found in the pig ovarian follicular fluid under our experimental procedure. Of the six known classes of IGFBPs, the complete primary structures of the first five have been determined, but not IGFBP-6. Using amino acid sequence information from a tryptic fragment of pig IGFBP-6 to prepare a probe, cDNA clones encoding rat and human IGFBP-6 have been isolated and characterized. The deduced amino acid sequence revealed that rat IGFBP-6 contains 201 amino acids with a calculated mol wt of 21,461, while the human homolog contains 216 amino acids with a calculated mol wt of 22,847. In addition, a distinctive feature of human and rat IGFBP-6 is that they lack, respectively, two and four of the 18 homologous cysteines that are present in all other five IGFBPs. The missing cysteines in IGFBP-6 resulted in the absence of the invariant Gly-Cys-Gly-Cys-Cys sequence in the amino-terminal region of the molecule. Human IGFBP-6 possesses a single Asn-linked glycosylation site near the carboxyl-terminal, whereas no potential Asn-linked glycosylation sites are present in the rat sequence. A single 1.3-kilobase IGFBP-6 mRNA was detected by Northern analysis in all rat tissues examined, including testis, intestine, adrenal, kidney, stomach, spleen, heart, lung, brain, and liver, indicating that this BP is a ubiquitous protein. The chromosome location of the IGFBP-6 gene in human has been determined using polymerase chain reaction on somatic cell hybrid DNAs of human and hamster, and the results showed that it is located on chromosome 12.
Mol Endocrinol 1991 Jul
PMID:Isolation and molecular cloning of insulin-like growth factor-binding protein-6. 171 83

The insulin-like growth factor-binding proteins (IGFBPs) are thought to determine the distribution of IGF-I and IGF-II between the blood and tissue compartments and to modulate their biological activities. A dynamic metabolic role for one of the IGFBPs, IGFBP-1, is suggested by the fact that plasma IGFBP-1 was increased after fasting and diabetes and rapidly decreased by refeeding or insulin treatment, respectively. IGFBP-1 mRNA also is increased in the livers of diabetic rats and decreased by insulin treatment. To understand the molecular basis for this regulation, we have examined the effects of insulin on IGFBP-1 and IGFBP-1 mRNA in the H4-II-E cell line derived from the well differentiated H35 rat hepatoma. IGFBP-1, identified by ligand blotting and immunoblotting, is the major IGFBP in H4-II-E cells. Incubation of H4-II-E cells with insulin for 24 h decreased IGFBP-1 in the culture medium by approximately 50%. Inhibition was observed at physiological concentrations of insulin (ED50, less than 0.5 nM), but not at higher concentrations of IGF-II. These results, together with the fact that H4-II-E cells do not possess IGF-I receptors with which insulin might cross-react, suggest that insulin acts via the insulin receptor. Insulin inhibited IGFBP-1 in the medium by 80% in the absence of glucose, suggesting that the inhibition is a direct effect of insulin; glucose exerted a smaller independent effect in the absence of insulin. Insulin decreased IGFBP-1 mRNA in H4-II-E cells by 50% within 1 h and by 90% after 2-12 h of incubation. Nuclear run-on transcription assays indicated a corresponding decrease in the rate of IGFBP-1 gene transcription. Pretreatment of H4-II-E cells with dexamethasone stimulated IGFBP-1 transcription and increased steady state IGFBP-1 mRNA; stimulation was abolished by insulin treatment, indicating that inhibition by insulin was dominant over induction by dexamethasone. Thus, insulin, acting through the insulin receptor, rapidly decreases the abundance of IGFBP-1 mRNA in H4-II-E cells. Regulation occurs at least in part at the level of gene transcription. We propose that regulation of IGFBP-1 synthesis is an important component of the regulation of IGFBP-1 by insulin in vivo.
Mol Endocrinol 1991 Aug
PMID:Insulin rapidly inhibits insulin-like growth factor-binding protein-1 gene expression in H4-II-E rat hepatoma cells. 171 86

The insulin receptor (IR) tyrosine kinase is essential for the regulation of different cellular functions by insulin. This may occur by a direct phosphorylation of membrane and/or cytoplasmic proteins by the IR tyrosine kinase. Hence it is important to identify putative physiological substrates for the IR tyrosine kinase. In this study we found that the glycoprotein fraction from rat liver membranes contain a 43 kDa protein (pp43) which, like the beta-subunit of IR, is phosphorylated in an insulin-dependent manner. A 25-fold enhancement of 32P incorporation into pp43 by insulin was found under optimal conditions. Half-maximal phosphorylation of pp43 and the beta-subunit of IR were attained at 66 nM and 60 nM insulin, respectively. Mn2+ (Ka = 1.0 mM) was much better than Mg2+ (Ka = 6.3 mM) in supporting pp43 phosphorylation. Insulin-stimulated phosphorylation of pp43 (t1/2 = 3.6 min) proceeded at a much slower rate compared to that of the beta-subunit of IR (t1/2 = 1.2 min). Phosphoamino acid analysis of pp43 revealed that both tyrosine and serine are phosphorylated in the ratio 4:1. Tyrosine, but not serine, phosphorylation was increased 12-fold by insulin. Phosphorylation of pp43 occurred on 4 major tryptic peptides. Comparison to the tryptic phosphopeptides from IR beta-subunit suggest that pp43 was not derived from IR beta-subunit by proteolysis. Our results suggest that pp43 may be an endogenous substrate for the IR tyrosine kinase.
Mol Cell Biochem 1991 Nov 13
PMID:Insulin-stimulated tyrosine phosphorylation of a 43 kDa protein in rat liver membranes. 172 68


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