Muscle developmental defects in heterogeneous nuclear Ribonucleoprotein A1 knockout mice.

Ting-Yuan Liu,Huai-Jen Tsai,Ya-Sian Chang,Yu-Chia Chen,Yuh-Jyh Jong,Jan-Gowth Chang,Yung-Fu Chang,Chien-Chin Lee

doi:10.1098/rsob.160303

Ting-Yuan Liu, Huai-Jen Tsai + Show 6 more

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https://doi.org/10.1098/rsob.160303

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Abstract

Heterogeneous ribonucleoprotein A1 (hnRNP A1) is crucial for regulating alternative splicing. Its integrated function within an organism has not, however, been identified. We generated hnRNP A1 knockout mice to study the role of hnRNP A1 in vivo. The knockout mice, hnRNP A1−/−, showed embryonic lethality because of muscle developmental defects. The blood pressure and heart rate of the heterozygous mice were higher than those of the wild-type mice, indicating heart function defects. We performed mouse exon arrays to study the muscle development mechanism. The processes regulated by hnRNP A1 included cell adhesion and muscle contraction. The expression levels of muscle development-related genes in hnRNP A1+/− mice were significantly different from those in wild-type mice, as detected using qRT-PCR. We further confirmed the alternative splicing patterns of muscle development-related genes including mef2c, lrrfip1, usp28 and abcc9. Alternative mRNA isoforms of these genes were increased in hnRNP A1+/− mice compared with wild-type mice. Furthermore, we revealed that the functionally similar hnRNP A2/B1 did not compensate for the expression of hnRNP A1 in organisms. In summary, our study demonstrated that hnRNP A1 plays a critical and irreplaceable role in embryonic muscle development by regulating the expression and alternative splicing of muscle-related genes.

Highlights

Alternative splicing is the most critical posttranscriptional mechanism by which cells can generate a diverse repertoire of protein isoforms from a limited number of genes
The heterogeneous ribonucleoprotein (hnRNP) A1 gene is disrupted by deleting exons 2–7, a strategy illustrated in figure 1a
There were 22 wild-type, 2 43 heterozygous and 17 homozygous mice. These results were similar to our expectations (20.5 wild-type, 41 heterozygous and 20.5 homozygous mice), supporting our speculation on embryonic lethality in the hnRNP A1 knockout mice

Summary

Introduction

Alternative splicing is the most critical posttranscriptional mechanism by which cells can generate a diverse repertoire of protein isoforms from a limited number of genes. This process plays a crucial regulatory role by altering the function, expression level and localization of gene products. Alternative splicing has been shown to play an important role in human diseases such as amyotrophic lateral sclerosis, frontotemporal lobe dementia, spinal muscular atrophy, Alzheimer’s disease and LMNA-related disorders [2,3]. Alternative splicing is modulated by cis-regulatory elements located within alternative exons or introns and by trans-acting splicing factors.

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