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Becker D, Weikard R, Heimes A, Hadlich F, Hammon HM, Meyerholz MM, Petzl W, Zerbe H, Schuberth HJ, Hoedemaker M, Schmicke M, Engelmann S, Kühn C. Allele-biased expression of the bovine APOB gene associated with the cholesterol deficiency defect suggests cis-regulatory enhancer effects of the LTR retrotransposon insertion. Sci Rep 2022; 12:13469. [PMID: 35931741 PMCID: PMC9355974 DOI: 10.1038/s41598-022-17798-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 07/31/2022] [Indexed: 11/09/2022] Open
Abstract
The insertion of an endogenous retroviral long terminal repeat (LTR) sequence into the bovine apolipoprotein B (APOB) gene is causal to the inherited genetic defect cholesterol deficiency (CD) observed in neonatal and young calves. Affected calves suffer from developmental abnormalities, symptoms of incurable diarrhoea and often die within weeks to a few months after birth. Neither the detailed effects of the LTR insertion on APOB expression profile nor the specific mode of inheritance nor detailed phenotypic consequences of the mutation are undisputed. In our study, we analysed German Holstein dairy heifers at the peak of hepatic metabolic load and exposed to an additional pathogen challenge for clinical, metabolic and hepatic transcriptome differences between wild type (CDF) and heterozygote carriers of the mutation (CDC). Our data revealed that a divergent allele-biased expression pattern of the APOB gene in heterozygous CDC animals leads to a tenfold higher expression of exons upstream and a decreased expression of exons downstream of the LTR insertion compared to expression levels of CDF animals. This expression pattern could be a result of enhancer activity induced by the LTR insertion, in addition to a previously reported artificial polyadenylation signal. Thus, our data support a regulatory potential of mobile element insertions. With regard to the phenotype generated by the LTR insertion, heterozygote CDC carriers display significantly differential hepatic expression of genes involved in cholesterol biosynthesis and lipid metabolism. Phenotypically, CDC carriers show a significantly affected lipomobilization compared to wild type animals. These results reject a completely recessive mode of inheritance for the CD defect, which should be considered for selection decisions in the affected population. Exemplarily, our results illustrate the regulatory impact of mobile element insertions not only on specific host target gene expression but also on global transcriptome profiles with subsequent biological, functional and phenotypic consequences in a natural in-vivo model of a non-model mammalian organism.
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Affiliation(s)
- Doreen Becker
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Rosemarie Weikard
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Annika Heimes
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Frieder Hadlich
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Harald M Hammon
- Institute of Nutritional Physiology, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Marie M Meyerholz
- Clinic for Ruminants with Ambulatory and Herd Health Services, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-University Munich, Oberschleißheim, Germany
- Institute for Immunology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Wolfram Petzl
- Clinic for Ruminants with Ambulatory and Herd Health Services, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-University Munich, Oberschleißheim, Germany
| | - Holm Zerbe
- Clinic for Ruminants with Ambulatory and Herd Health Services, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-University Munich, Oberschleißheim, Germany
| | | | - Martina Hoedemaker
- Clinic for Cattle, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Marion Schmicke
- Faculty of Natural Sciences III, Martin-Luther University Halle-Wittenberg, Halle, Germany
| | - Susanne Engelmann
- Institute for Microbiology, Technical University Braunschweig, Brunswick, Germany
- Microbial Proteomics, Helmholtz Centre for Infection Research, Brunswick, Germany
| | - Christa Kühn
- Institute of Genome Biology, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany.
- Agricultural and Environmental Faculty, University of Rostock, Rostock, Germany.
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