مجال
التميز

تميز دراسي و بحثي

البحوث المنشورة

البحث (1):

عنوان البحث:

The role of IREB2 and transforming
growth factor  beta-1 genetic variants in COPD:
a replication case-control study

رابط إلى البحث:

Link

تاريخ النشر:

14/02/2011

موجز عن البحث:

Background:

Genetic factors are known to contribute to COPD susceptibility and
these factors are not fully understood. Conflicting results have been
reported for many genetic studies of candidate genes based on their role in
the disease. Genome-wide association studies in combination with expression
profiling have identified a number of new candidates including IREB2.
A meta-analysis has implicated transforming growth factor beta-1 (TGFbeta1)
as a contributor to disease susceptibility.

Methods:

We have examined previously reported
associations in both genes in a collection of 1017 white COPD patients and
912 non-diseased smoking controls. Genotype information was obtained for
seven SNPs in the IREB2 gene, and for four SNPs in the TGFbeta1 gene.
Allele and genotype frequencies were compared between COPD cases and
controls, and odds ratios were calculated. The analysis was adjusted for age,
sex, smoking and centre, including interactions of age, sex and smoking with
centre.

Results:

Our data replicate the association of IREB2 SNPs in association
with COPD for SNP rs2568494, rs2656069 and rs12593229 with respective
adjusted p-values of 0.0018, 0.0039 and 0.0053. No significant associations
were identified for TGFbeta1.

Conclusions:

These studies have therefore confirmed that the IREB2 locus is
a contributor to COPD susceptibility and suggests a new pathway in COPD
pathogenesis invoking iron homeostasis.

المؤتمرات العلمية:

المؤتمر (1):

عنوان المؤتمر:

European
Respiratory Society Annual Congress

تاريخ الإنعقاد:

01/09/2012

بلد
ومكان الإنعقاد:

Vienna, Austria

طبيعة المشاركة:

Poster
Discussion

عنوان
المشاركة:

Investigating the role of IREB2 genetic
variants in susceptibility to COPD

موجز عن المشاركة:

The IREB2 gene encodes the iron-binding
protein 2 (IRP2), which is a major regulator of iron homeostasis. Several
studies, including genome wide association studies, have shown that the IREB2 locus is a contributor to COPD
susceptibility. In a previous report, we observed significant associations of
seven IREB2 genetic variants (6 intronic and 1 in exon 21) with increased
risk of COPD in a large case-control study. Subsequent in-silico analysis
showed that six of these SNPs were in tight linkage disequilibrium (r²=0.99)
with two additional polymorphisms that lie within the promoter (rs2656070)
and the 3’UTR (rs12899351) region of IREB2 gene. The promoter SNP is
predicted to disrupt the binding of two transcription factors (SP-1 and AP-1)
while the 3’UTR SNP is located in a region that is predicted to be a target
site of micro RNAs mir-1285 and mir-5096, by PITA software and miRBase
alignment tool, respectively and may alter
translation. The aims of this study were to evaluate the functional
consequences of these variants on IREB2 expression.

To test the effect of the promoter SNP on transcriptional
activity, two fragments were amplified and cloned from genomic DNA
corresponding to homozygotes for each allele of rs2656070. The first fragment
contained 1.08 kb of sequence upstream of the IREB2 transcription start site.
The second fragment spans 413bp of the 5’ region predicted to harbor
regulatory elements by bioinformatics analysis. Both fragments were inserted
upstream of the luciferase reporter gene in the pGL3-Basic vector and then
transfected into the A549 cell line. Our results show a significant promoter
activity equating to a mean 101-fold and 130-fold increase in reporter gene
activation for the 1.08 kb and 413 bp fragments, respectively. There was no
significant difference (p-value of 0.19) in the relative luciferase
expression in A549 cells transiently transfected with rs2656070 wild type (G)
construct compared with the risk allele (A) for both fragments under basal
conditions. Additional analysis will be undertaken to examine the effect of
the SNP rs2656070 under conditions that are known to stimulate IREB2 expression including hypoxia and
low iron cellular levels.

For the 3’UTR SNP, two fragments for the wild type (TT) and the
risk allele (CC) of rs12899351 were cloned immediately downstream of the
luciferase gene in pmirGLO vector. The inserts are 22 base pairs long
encompassing the potential miRNA (mir-1285 and mir-5096) target element of
the IREB2 3’UTR. The constructs were transfected into HepG2 cells that are
known to express mir-1285. Our result showed that the expression of
luciferase gene from the wild type construct was similar to that of the
control construct (vector with no insert). Additionally, the result revealed
that there is no difference in reporter gene expression from both wild type
and mutant constructs. These findings indicate that the cloned sequence was
not recognized by mir-1285. Additional analysis will be carried out to
investigate the regulatory role of mir-5096 on IREB2 expression.