Investigation of candidate genes for metabolic disorders expressed in liver and pituitary gland by comparing the RNA-seq data of Polish-HF and Polish-Red cattle

Background: Metabolic disorder is a major health problem in dairy cattle, particularly to high milk producing dairy cattle. It is worthily emphasized that metabolic diseases have a very complex etiology and pathogenesis, and the impact of these diseases on hepatic and pituitary gland gene expression and organism oxidative balance is not fully described. The presented study was aimed to determine and predict the hepatic and pituitary gland expression of potential candidate genes in context to maintenance of oxidative balance, negative nitrogen balance, as well as ketosis in Polish HF and Polish Red cattle. Methods: Based on the RNA-seq experimental data, we investigated the candidate genes ( SOD1, SOD2, SOD3, GPx2, GPx3, GPx5, GPx6, GPx7, GPx8, BDH1, FN1, ACSL3 , HMGCL, HMGCS2, BDH2, ACSL6 , ACAT2, IDH3B, ACAT1, HMGCS1, ACSL4 , ACSL1 , PC, CPT1A, OXCT1 and ACSL5 respectively) expressions in liver and pituitary gland tissues of Polish HF and Polish Red cattle. The RNA-seq experimental design comprised of young bulls aged between 6 to 12 months were investigated. For each breed, six liver and six pituitary gland tissues were sequenced using Next-seq 500 illumina platform. The RNA-seq expression data were normalized by the reads per kilobase of exon per million reads mapped (RPKM) method. Results: By comparing the RNA-seq data of liver and pituitary gland tissues, the investigated candidate genes were highly expressed in the hepatic tissues than to pituitary gland in investigated cattle breeds. However, by comparing the Polish HF and Polish Red cattle breeds, results revealed a similar trend of gene expression profiling of all investigated candidate genes for both metabolic tissues. In case of hepatic gene expression profiling, the SOD1, FN1, HMGCL, HMGCS2, ACAT2, ACAT1, HMGCS1, ACSL1 and ACSL5 were highly expressed (FPKM values of >40), followed by SOD2, GPX3, IDH3B, PC and BDH2 as moderately expressed (FPKM values: >10 to 40), followed by SOD2, GPX8, IDH3B, ACAT1, ACSL4 and PC as moderately expressed (FPKM values: >10 to <40), and averagely expressed SOD3, GPX3,GPX5, GPX6, GPX7, GPX2, BDH1, BDH2, ACSL3 , ACSL6 , CPT1A, OXCT1, FN1, HMGCL, HMGCS2, ACAT2, ACAT1, HMGCS1, ACSL1 and ACSL5 respectively, in Polish HF and Polish Red breeds. Conclusions: Based on this presented results on hepatic and pituitary gland gene expression, a further research plan is an essential pre-requisite to validate the identified candidate genes. Study indicated the understanding the genetic factors that predispose metabolic disorders in cattle would benefit the dairy industry as a whole by providing producers, breeding services, and veterinarians a tool to forecast a cow’s susceptibility to metabolic disorders.