HTR4 gene structure and altered expression in the developing lung

Hodge, Emily and Nelson, Carl P. and Miller, Suzanne and Billington, Charlotte K. and Stewart, Ceri E. and Swan, Caroline and Malarstig, Anders and Henry, Amanda P. and Gowland, Catherine and Melén, Erik and Hall, Ian P. and Sayers, Ian (2013) HTR4 gene structure and altered expression in the developing lung. Respiratory Research, 14 (77). pp. 1-13. ISSN 1465-9921

[img] PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
Available under Licence Creative Commons Attribution.
Download (2MB)


Background: Meta-analyses of genome-wide association studies (GWAS) have identified single nucleotide

polymorphisms (SNPs) spanning the 5-hydroxytryptamine receptor 4 (5-HT4R) gene (HTR4) associated with lung

function. The aims of this study were to i) investigate the expression profile of HTR4 in adult and fetal lung tissue

and cultured airway cells, ii) further define HTR4 gene structure and iii) explore the potential functional implications of key SNPs using a bioinformatic approach.

Methods: Following reverse transcription (RT)-PCR in human brain, 5′ rapid amplification of cDNA ends (5′ RACE) was used to examine the exonic structure of HTR4 at the 5′ end. Quantitative (Q)-PCR was used to quantify HTR4 mRNA expression in total RNA from cultured airway cells and whole lung tissue. Publically available gene microarray data on fetal samples of estimated gestational age 7–22 weeks were mined for HTR4 expression. Immunohistochemistry (IHC; in adult and fetal lung tissue) and a radioligand binding assay (in cultured airway cells) were used to analyze 5HT4R protein expression.

Results: IHC in adult lung, irrespective of the presence of chronic obstructive pulmonary disease (COPD), suggested low

level expression of 5-HT4R protein, which was most prominent in alveolar pneumocytes. There was evidence of differential 5-HT4R protein levels during gestation in fetal lung, which was also evident in gene expression microarray data. HTR4 mRNA expression, assessed by Q-PCR, was <0.5% relative to brain in total adult lung tissue and in human airway smooth muscle (HASM) and bronchial epithelial cells (HBEC) derived from adult donors. Radioligand binding experiments also indicated that HBEC and HASM cells did not express a significant 5-HT4R population. 5′ RACE in brain identified a novel Nterminal

variant, containing an extended N-terminal sequence. The functional significance of key HTR4 SNPs was investigated using the encyclopedia of DNA elements consortium (ENCODE) dataset. These analyses identified multiple alterations in regulatory motifs for transcription factors implicated in lung development, including Foxp1.

Conclusions: Taken together, these data suggest a role for HTR4 in lung development, which may at least in part explain

the genetic association with lung function.

Item Type: Article
Schools/Departments: University of Nottingham UK Campus > Faculty of Medicine and Health Sciences > School of Medicine > Medical Education Unit and Medical Courses Office
Identification Number:
Depositing User: Johnson, Mrs Alison
Date Deposited: 02 May 2014 10:42
Last Modified: 15 Sep 2016 01:01

Actions (Archive Staff Only)

Edit View Edit View