Functional Diversity of Human Basic Helix-Loop-Helix Transcription Factor TCF4 Isoforms Generated by Alternative 5′ Exon Usage and Splicing

BACKGROUND: Transcription factor 4 (TCF4 alias ITF2, E2-2, ME2 or SEF2) is a ubiquitous class A basic helix-loop-helix protein that binds to E-box DNA sequences (CANNTG). While involved in the development and functioning of many different cell types, recent studies point to important roles for TCF4 in the nervous system. Specifically, human TCF4 gene is implicated in susceptibility to schizophrenia and TCF4 haploinsufficiency is the cause of the Pitt-Hopkins mental retardation syndrome. However, the structure, expression and coding potential of the human TCF4 gene have not been described in detail. PRINCIPAL FINDINGS: In the present study we used human tissue samples to characterize human TCF4 gene structure and TCF4 expression at mRNA and protein level. We report that although widely expressed, human TCF4 mRNA expression is particularly high in the brain. We demonstrate that usage of numerous 5' exons of the human TCF4 gene potentially yields in TCF4 protein isoforms with 18 different N-termini. In addition, the diversity of isoforms is increased by alternative splicing of several internal exons. For functional characterization of TCF4 isoforms, we overexpressed individual isoforms in cultured human cells. Our analysis revealed that subcellular distribution of TCF4 isoforms is differentially regulated: Some isoforms contain a bipartite nuclear localization signal and are exclusively nuclear, whereas distribution of other isoforms relies on heterodimerization partners. Furthermore, the ability of different TCF4 isoforms to regulate E-box controlled reporter gene transcription is varied depending on whether one or both of the two TCF4 transcription activation domains are present in the protein. Both TCF4 activation domains are able to activate transcription independently, but act synergistically in combination. CONCLUSIONS: Altogether, in this study we have described the inter-tissue variability of TCF4 expression in human and provided evidence about the functional diversity of the alternative TCF4 protein isoforms

Quantitative Proteomics Identify Novel miR-155 Target Proteins

Background: MicroRNAs are 22 nucleotides long non-coding RNAs and exert their function either by transcriptional or translational inhibition. Although many microRNA profiles in different tissues and disease states have already been discovered, only little is known about their target proteins. The microRNA miR-155 is deregulated in many diseases, including cancer, where it might function as an oncoMir. Methodology/Principal Findings: We employed a proteomics technique called ‘‘stable isotope labelling by amino acids in cell culture’ ’ (SILAC) allowing relative quantification to reliably identify target proteins of miR-155. Using SILAC, we identified 46 putative miR-155 target proteins, some of which were previously reported. With luciferase reporter assays, CKAP5 was confirmed as a new target of miR-155. Functional annotation of miR-155 target proteins pointed to a role in cell cycle regulation. Conclusions/Significance: To the best of our knowledge we have investigated for the first time miR-155 target proteins in the HEK293T cell line in large scale. In addition, by comparing our results to previously identified miR-155 target proteins i

Valsartan Improves Adipose Tissue Function in Humans with Impaired Glucose Metabolism: A Randomized Placebo-Controlled Double-Blind Trial

<div><h3>Background</h3><p>Blockade of the renin-angiotensin system (RAS) reduces the incidence of type 2 diabetes mellitus. In rodents, it has been demonstrated that RAS blockade improved adipose tissue (AT) function and glucose homeostasis. However, the effects of long-term RAS blockade on AT function have not been investigated in humans. Therefore, we examined whether 26-wks treatment with the angiotensin II type 1 receptor blocker valsartan affects AT function in humans with impaired glucose metabolism (IGM).</p> <h3>Methodology/Principal Findings</h3><p>We performed a randomized, double-blind, placebo-controlled parallel-group study, in which 38 subjects with IGM were treated with valsartan (VAL, 320 mg/d) or placebo (PLB) for 26 weeks. Before and after treatment, an abdominal subcutaneous AT biopsy was collected for measurement of adipocyte size and AT gene/protein expression of angiogenesis/capillarization, adipogenesis, lipolytic and inflammatory cell markers. Furthermore, we evaluated fasting and postprandial AT blood flow (ATBF) (¹³³Xe wash-out), systemic inflammation and insulin sensitivity (hyperinsulinemic-euglycemic clamp). VAL treatment markedly reduced adipocyte size (<em>P</em><0.001), with a shift toward a higher proportion of small adipocytes. In addition, fasting (<em>P</em> = 0.043) and postprandial ATBF (<em>P</em> = 0.049) were increased, whereas gene expression of angiogenesis/capillarization, adipogenesis and macrophage infiltration markers in AT was significantly decreased after VAL compared with PLB treatment. Interestingly, the change in adipocyte size was associated with alterations in insulin sensitivity and reduced AT gene expression of macrophage infiltration markers. VAL did not alter plasma monocyte-chemoattractant protein (MCP)-1, TNF-α, adiponectin and leptin concentrations.</p> <h3>Conclusions/Significance</h3><p>26-wks VAL treatment markedly reduced abdominal subcutaneous adipocyte size and AT macrophage infiltration markers, and increased ATBF in IGM subjects. The VAL-induced decrease in adipocyte size was associated with reduced expression of macrophage infiltration markers in AT. Our findings suggest that interventions targeting the RAS may improve AT function, thereby contributing to a reduced risk of developing cardiovascular disease and type 2 diabetes.</p> <h3>Trial Registration</h3><p>Trialregister.nl NTR721 (ISRCTN Registry: ISRCTN<a href="http://www.controlled-trials.com/isrctn/pf/42786336">42786336</a>)</p> </div

Effectiveness and tolerability of treatment intensification to basal&ndash;bolus therapy in patients with type 2 diabetes on previous basal insulin-supported oral therapy with insulin glargine or supplementary insulin therapy with insulin glulisine: the PARTNER observational study

Martin Pfohl,1 Thorsten Siegmund,2 Stefan Pscherer,3 Katrin Pegelow,4 Jochen Seufert5 1Medizinische Klinik I, Evangelisches Bethesda-Klinikum GmbH, Duisburg, Germany; 2St&auml;dtisches Klinikum M&uuml;nchen GmbH, Klinikum Bogenhausen, III. Medizinische Abteilung, M&uuml;nchen, Germany; 3Klinisches Diabeteszentrum S&uuml;dostbayern, Innere Medizin &ndash; Diabetologie, Traunstein, Germany; 4Sanofi-Aventis Deutschland GmbH, Berlin, Germany; 5Medizinische Universit&auml;tsklinik, Klinik f&uuml;r Innere Medizin II, Abteilung f&uuml;r Endokrinologie und Diabetologie, Freiburg, Germany Background: Due to the progressive nature of type 2 diabetes mellitus (T2DM), antidiabetic treatment needs to be continuously intensified to avoid long-term complications. In T2DM patients on either basal insulin-supported oral therapy (BOT) or supplementary insulin therapy (SIT) presenting with HbA1c values above individual targets for 3&ndash;6 months, therapy should be intensified. This study investigated effectiveness and tolerability of an intensification of BOT or SIT to a basal&ndash;bolus therapy (BBT) regimen in T2DM patients in daily clinical practice. Methods: This noninterventional, 8-month, prospective, multicenter study evaluated parameters of glucose control, occurrence of adverse events (eg, hypoglycemia), and acceptance of devices in daily clinical practice routine after 12 and 24 weeks of intensifying insulin therapy to a BBT regimen starting from either preexisting BOT with insulin glargine (pre-BOT) or preexisting SIT with &ge;3 daily injections of insulin glulisine (pre-SIT). Results: A total of 1,530 patients were documented in 258 German medical practices. A total of 1,301 patients were included in the full analysis set (55% male, 45% female; age median 64 years; body mass index median 30.8 kg/m2; pre-BOT: n=1,072; pre-SIT: n=229), and 1,515 patients were evaluated for safety. After 12 weeks, HbA1c decreased versus baseline (pre-BOT 8.67%; pre-SIT 8.46%) to 7.73% and 7.66%, respectively (&Delta; mean -0.94% and -0.80%; P&lt;0.0001). At week 24, HbA1c was further reduced to 7.38% and 7.30%, respectively (&Delta; mean &ndash;1.29% and -1.15%; P&lt;0.0001), with a mean reduction of fasting blood glucose values in both treatment groups by more than 46 mg/dL. An HbA1c goal of &le;6.5% was reached by 17.9% (pre-BOT) and 18.6% (pre-SIT), and an HbA1c &le;7.0% by 46.1% (pre-BOT) and 43.0% (pre-SIT) of patients. During 24 weeks, severe as well as serious hypoglycemic events were rare (pre-BOT: n=5; pre-SIT: n=2; pretreated with both insulins: n=1). Conclusion: Intensifying glargine-based BOT or glulisine-based SIT to a BBT regimen in poorly controlled T2DM patients in daily routine care led to marked improvements of glycemic control and was well tolerated. Keywords: type 2 diabetes, clinical practice, BBT, insulin glargine, insulin glulisine, basal&ndash;bolus therap

Effectiveness and safety of insulin glargine 300 U/mL in insulin-naive patients with type 2 diabetes after failure of oral therapy in a real-world setting.

Aim To evaluate the effectiveness and safety of initiating basal insulin-supported oral therapy (BOT) with insulin glargine 300 U/mL (Gla-300) in patients with type 2 diabetes inadequately controlled on oral antidiabetic drugs (OADs). Materials and Methods This non-interventional, multi-centre, prospective 52-week study, conducted in Germany and Switzerland, documented patients with type 2 diabetes with an HbA1c of between 7.5% and 10.0%, currently treated with OADs, after the physician had decided to start a BOT regimen with Gla-300. The primary endpoint was the rate of achievement of the individualized predefined HbA1c target. Results Of 1748 patients included, 1153 comprised the full analysis set, of whom 721 completed documentation of 12 months of Gla-300 treatment. Twelve months after starting Gla-300, 49.9% achieved their individualized HbA1c target, and 61.1% achieved either their HbA1c target or a fasting plasma glucose (FPG) of &lt;= 110 mg/dL. Mean HbA1c decreased by -1.22% +/- 1.05% to 7.28% +/- 0.92% and mean FPG by -51.5 (+/- 48.63) mg/dl to 132.9 +/- 33.0 mg/dL. Median duration of HbA1c target achievement was 341 days and probability to remain on target after 6 months was 81%. Hypoglycaemia incidence and rates remained low after 12 months of Gla-300 treatment; no severe or severe nocturnal hypoglycaemia was observed. Body weight remained unchanged. Conclusions Starting a BOT regimen with Gla-300 allowed about 60% of 721 German and Swiss patients with inadequately controlled type 2 diabetes to achieve glycaemic control within 12 months in daily clinical practice. Glycaemic control was achieved without weight gain or increased risk of nocturnal or severe hypoglycaemia