Identification of novel HNF1B mRNA splicing variants and their qualitative and semi-quantitative profile in selected healthy and tumour tissues

Jan Hojny,David Cibula,Michaela Bartu,Kristyna Nemejcova,Lenka Plincelnerova,Vladimir Fryba,Pavel Dundr,Jan Sevcik,Ivana Struzinska,Eva Krkavcova

doi:10.1038/s41598-020-63733-x

Jan Hojny, David Cibula + Show 8 more

Open Access

https://doi.org/10.1038/s41598-020-63733-x

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Abstract

Hepatocyte nuclear factor-1-beta (HNF1B) is a transcription factor crucial for the development of several tissues, and a promising biomarker of certain solid tumours. Thus far, two HNF1B alternative splicing variants (ASVs) have been described, however, the complete spectrum, prevalence and role of HNF1B ASVs in tumorigenesis are unclear. Considering the equivocal data about HNF1B ASVs and expression presented in literature, our aim was to characterize the spectrum of HNF1B mRNA splicing variants across different tissues. Here, we characterize HNF1B ASVs with high sensitivity in carcinomas of the uterine corpus, large intestine, kidney, pancreas, and prostate, with selected paired healthy tissues, using the previously described multiplex PCR and NGS approach. We identified 45 ASVs, of which 43 were novel. The spectrum and relative quantity of expressed ASVs mRNA differed among the analysed tissue types. Two known (3p, Δ7_8) and two novel (Δ7, Δ8) ASVs with unknown biological functions were detected in all the analysed tissues in a higher proportion. Our study reveals the wide spectrum of HNF1B ASVs in selected tissues. Characterization of the HNF1B ASVs is an important prerequisite for further expression studies to delineate the HNF1B splicing pattern, potential ASVs functional impact, and eventual refinement of HNF1B’s biomarker role.

Highlights

Hepatocyte nuclear factor-1-beta (HNF1B) is a transcription factor crucial for the development of several tissues, and a promising biomarker of certain solid tumours
Two other alternative splicing variants (ASVs) were detected with read counts
There are studies which define HNF1B as a pro-differentiation factor with a potent tumour-suppressive activity in healthy tissues[6,7,19], while other studies point to its role as an oncogene in tissue-derived cancer cells which have undergone malignant transformation, inducing a cancerous phenotype and activating the formation of invasive phenotypes through epithelial-mesenchymal transition[11,14]

Summary

Introduction

Hepatocyte nuclear factor-1-beta (HNF1B) is a transcription factor crucial for the development of several tissues, and a promising biomarker of certain solid tumours. Considering the equivocal data about HNF1B ASVs and expression presented in literature, our aim was to characterize the spectrum of HNF1B mRNA splicing variants across different tissues. Characterization of the HNF1B ASVs is an important prerequisite for further expression studies to delineate the HNF1B splicing pattern, potential ASVs functional impact, and eventual refinement of HNF1B’s biomarker role. The HNF1B gene comprises 9 exons and codes for a protein with 3 important functional domains: the N-terminal dimerization domain, the DNA-binding domain (consisting of the Pit1/Oct-1/Unc-86-POU-homeodomain and a POU-specific domain), and the C-terminal transactivation domain (Fig. 1)[4]. The green, grey, blue and orange areas illustrate the coding areas for functional domains across the HNF1B transcripts. The scheme was adopted[2] and modified

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