Limits...
Alternative splicing of TCF7L2 gene in omental and subcutaneous adipose tissue and risk of type 2 diabetes.

Prokunina-Olsson L, Kaplan LM, Schadt EE, Collins FS - PLoS ONE (2009)

Bottom Line: We hypothesized that these genetic variants might increase the risk of T2D through regulation of alternative splicing or expression level of TCF7L2 in human adipose tissue.TCF7L2 expression in both types of adipose tissue was not associated with SNPs rs7903146 and rs12255372, T2D status and blood levels of glucose or glycosylated hemoglobin (HbA1c).Expression of TCF7L2 alternatively spliced forms may have different functional roles in omental and subcutaneous adipose tissue but is not associated with SNPs rs7903146 and rs12255372 or T2D status.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America. prokuninal@mail.nih.gov

ABSTRACT

Background: Single nucleotide polymorphisms (SNPs) rs7903146 and rs12255372 located within TCF7L2 gene have been identified as the strongest common genetic risk factors for development of type 2 diabetes (T2D). We hypothesized that these genetic variants might increase the risk of T2D through regulation of alternative splicing or expression level of TCF7L2 in human adipose tissue.

Methodology/principal findings: Expression of 13 assays detecting alternatively spliced forms of TCF7L2 was measured by quantitative reverse-transcriptase PCR (qRT-PCR) in paired biopsies of omental and subcutaneous adipose tissue from 159 obese individuals (BMI 54.6+/-12.2 kg/m(2)). TCF7L2 expression in both types of adipose tissue was not associated with SNPs rs7903146 and rs12255372, T2D status and blood levels of glucose or glycosylated hemoglobin (HbA1c). Expression of assays "ex12-13", "ex12-14" and "ex13-13a" detecting C-terminal alternative exons of TCF7L2 was higher in subcutaneous compared to omental adipose tissue by 1.46 fold (p = 6.5x10(-15)), 1.41 fold (p = 1.4x10(-9)) and 1.26 fold (p = 4.7x10(-6)) in the control group and by 1.86 fold (p = 1.7x10(-4)), 1.77 fold (p = 7.3x10(-4)) and 1.58 fold (p = 6.1x10(-4)) in the T2D group. A pathway enrichment analysis on transcripts significantly co-expressed with TCF7L2 in a microarray set combined with individual expression assays, suggested tissue-specific roles of TCF7L2 splicing forms in regulation of transcription, signal transduction and cell adhesion.

Conclusions: Expression of TCF7L2 alternatively spliced forms may have different functional roles in omental and subcutaneous adipose tissue but is not associated with SNPs rs7903146 and rs12255372 or T2D status.

Show MeSH

Related in: MedlinePlus

Alternative splicing forms of TCF7L2 with increased expression in subcutaneous compared to omental adipose.A. Constitutive exons 11 and 14 are marked as black rectangles, alternative exons 12, 13, 13a, 13b are marked as white rectangles, black triangles above exons indicate location of alternative stop codons that define protein reading frames: short (S), medium (M) or long (L); B. Alternative splicing form with exons 11-12-13-13a (GenBank FJ010174) has an alternative stop codon within exon 13a and encodes a protein with short reading frame; C. Alternative splicing form with exons 11-12-14 (GenBank FJ010170) has an alternative stop codon in the beginning of exon 14 and encodes a protein with medium reading frame. Positions of expression assays “ex12-13”, “ex13-13a” and “12-14” used in this study are indicated above corresponding exons. Assays “ex12-13”, “ex13-13a” and “12-14” detect all splicing forms of TCF7L2 that include alternative exon 12.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2747626&req=5

pone-0007231-g002: Alternative splicing forms of TCF7L2 with increased expression in subcutaneous compared to omental adipose.A. Constitutive exons 11 and 14 are marked as black rectangles, alternative exons 12, 13, 13a, 13b are marked as white rectangles, black triangles above exons indicate location of alternative stop codons that define protein reading frames: short (S), medium (M) or long (L); B. Alternative splicing form with exons 11-12-13-13a (GenBank FJ010174) has an alternative stop codon within exon 13a and encodes a protein with short reading frame; C. Alternative splicing form with exons 11-12-14 (GenBank FJ010170) has an alternative stop codon in the beginning of exon 14 and encodes a protein with medium reading frame. Positions of expression assays “ex12-13”, “ex13-13a” and “12-14” used in this study are indicated above corresponding exons. Assays “ex12-13”, “ex13-13a” and “12-14” detect all splicing forms of TCF7L2 that include alternative exon 12.

Mentions: Expression of several assays was higher in subcutaneous compared to omental adipose tissue both in the control and T2D groups: 1.46 and 1.86-fold for assay “ex12-13”, 1.41 and 1.77-fold for assay “ex12-14” and 1.26 and 1.58-fold for assay “ex13-13a” (Table 4). Only expression of alternative exon 3a (assay “ex3a-4”) was decreased in subcutaneous compared to adipose tissue (0.81 fold) in the control group, but not in the T2D group (0.91 fold) (Table 4). The results for assays “ex12-13”, “13-13a” and “12-14” will remain significant even after adjustment for multiple tests. Different ways of normalization of TCF7L2 expression (by expression levels of endogenous controls B2M, GAPDH or both genes together) did not significantly affect the conclusions (data not shown). The assays “ex12-13”, “13-13a” and “12-14” detect two distinct splicing forms that include alternative exon 12 (Figure 2). The first form (GenBank FJ010174) includes C-terminal exons 11-12-13-13a and encodes a protein with a short reading frame terminated by an alternative stop codon within exon 13a. The second form (GenBank FJ010170) includes exons 11-12-14 and encodes a protein with a medium reading frame terminated by an alternative stop codon in the beginning of exon 14 (Fig. 2).


Alternative splicing of TCF7L2 gene in omental and subcutaneous adipose tissue and risk of type 2 diabetes.

Prokunina-Olsson L, Kaplan LM, Schadt EE, Collins FS - PLoS ONE (2009)

Alternative splicing forms of TCF7L2 with increased expression in subcutaneous compared to omental adipose.A. Constitutive exons 11 and 14 are marked as black rectangles, alternative exons 12, 13, 13a, 13b are marked as white rectangles, black triangles above exons indicate location of alternative stop codons that define protein reading frames: short (S), medium (M) or long (L); B. Alternative splicing form with exons 11-12-13-13a (GenBank FJ010174) has an alternative stop codon within exon 13a and encodes a protein with short reading frame; C. Alternative splicing form with exons 11-12-14 (GenBank FJ010170) has an alternative stop codon in the beginning of exon 14 and encodes a protein with medium reading frame. Positions of expression assays “ex12-13”, “ex13-13a” and “12-14” used in this study are indicated above corresponding exons. Assays “ex12-13”, “ex13-13a” and “12-14” detect all splicing forms of TCF7L2 that include alternative exon 12.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2747626&req=5

pone-0007231-g002: Alternative splicing forms of TCF7L2 with increased expression in subcutaneous compared to omental adipose.A. Constitutive exons 11 and 14 are marked as black rectangles, alternative exons 12, 13, 13a, 13b are marked as white rectangles, black triangles above exons indicate location of alternative stop codons that define protein reading frames: short (S), medium (M) or long (L); B. Alternative splicing form with exons 11-12-13-13a (GenBank FJ010174) has an alternative stop codon within exon 13a and encodes a protein with short reading frame; C. Alternative splicing form with exons 11-12-14 (GenBank FJ010170) has an alternative stop codon in the beginning of exon 14 and encodes a protein with medium reading frame. Positions of expression assays “ex12-13”, “ex13-13a” and “12-14” used in this study are indicated above corresponding exons. Assays “ex12-13”, “ex13-13a” and “12-14” detect all splicing forms of TCF7L2 that include alternative exon 12.
Mentions: Expression of several assays was higher in subcutaneous compared to omental adipose tissue both in the control and T2D groups: 1.46 and 1.86-fold for assay “ex12-13”, 1.41 and 1.77-fold for assay “ex12-14” and 1.26 and 1.58-fold for assay “ex13-13a” (Table 4). Only expression of alternative exon 3a (assay “ex3a-4”) was decreased in subcutaneous compared to adipose tissue (0.81 fold) in the control group, but not in the T2D group (0.91 fold) (Table 4). The results for assays “ex12-13”, “13-13a” and “12-14” will remain significant even after adjustment for multiple tests. Different ways of normalization of TCF7L2 expression (by expression levels of endogenous controls B2M, GAPDH or both genes together) did not significantly affect the conclusions (data not shown). The assays “ex12-13”, “13-13a” and “12-14” detect two distinct splicing forms that include alternative exon 12 (Figure 2). The first form (GenBank FJ010174) includes C-terminal exons 11-12-13-13a and encodes a protein with a short reading frame terminated by an alternative stop codon within exon 13a. The second form (GenBank FJ010170) includes exons 11-12-14 and encodes a protein with a medium reading frame terminated by an alternative stop codon in the beginning of exon 14 (Fig. 2).

Bottom Line: We hypothesized that these genetic variants might increase the risk of T2D through regulation of alternative splicing or expression level of TCF7L2 in human adipose tissue.TCF7L2 expression in both types of adipose tissue was not associated with SNPs rs7903146 and rs12255372, T2D status and blood levels of glucose or glycosylated hemoglobin (HbA1c).Expression of TCF7L2 alternatively spliced forms may have different functional roles in omental and subcutaneous adipose tissue but is not associated with SNPs rs7903146 and rs12255372 or T2D status.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America. prokuninal@mail.nih.gov

ABSTRACT

Background: Single nucleotide polymorphisms (SNPs) rs7903146 and rs12255372 located within TCF7L2 gene have been identified as the strongest common genetic risk factors for development of type 2 diabetes (T2D). We hypothesized that these genetic variants might increase the risk of T2D through regulation of alternative splicing or expression level of TCF7L2 in human adipose tissue.

Methodology/principal findings: Expression of 13 assays detecting alternatively spliced forms of TCF7L2 was measured by quantitative reverse-transcriptase PCR (qRT-PCR) in paired biopsies of omental and subcutaneous adipose tissue from 159 obese individuals (BMI 54.6+/-12.2 kg/m(2)). TCF7L2 expression in both types of adipose tissue was not associated with SNPs rs7903146 and rs12255372, T2D status and blood levels of glucose or glycosylated hemoglobin (HbA1c). Expression of assays "ex12-13", "ex12-14" and "ex13-13a" detecting C-terminal alternative exons of TCF7L2 was higher in subcutaneous compared to omental adipose tissue by 1.46 fold (p = 6.5x10(-15)), 1.41 fold (p = 1.4x10(-9)) and 1.26 fold (p = 4.7x10(-6)) in the control group and by 1.86 fold (p = 1.7x10(-4)), 1.77 fold (p = 7.3x10(-4)) and 1.58 fold (p = 6.1x10(-4)) in the T2D group. A pathway enrichment analysis on transcripts significantly co-expressed with TCF7L2 in a microarray set combined with individual expression assays, suggested tissue-specific roles of TCF7L2 splicing forms in regulation of transcription, signal transduction and cell adhesion.

Conclusions: Expression of TCF7L2 alternatively spliced forms may have different functional roles in omental and subcutaneous adipose tissue but is not associated with SNPs rs7903146 and rs12255372 or T2D status.

Show MeSH
Related in: MedlinePlus