Gene expression during testis development in Duroc boars

Abstract

Androstenone is a steroid pheromone occurring in the pubertal Leydig cells. Breeding against androstenone can decrease pheromone odour in swine meat but appears to cause unwanted side effects such as delayed onset of puberty. To study causality, global gene expression in developing boar testes at 12, 16, 20 and 27 weeks was investigated using a porcine cDNA microarray. The morphological status and androgenic levels of the same individuals have been described in a previous publication. In the present paper, expression of genes and pathways has been analysed with reference to these findings. Nine clusters of genes with significant differential expression over time and 49 functional charts were found in the analysed testis samples. Prominent pathways in the prepubertal testis were associated with tissue renewal, cell respiration and increased endocytocis. E-cadherines may be associated with the onset of pubertal development. With elevated steroidogenesis (weeks 16 to 27), there was an increase in the expression of genes in the MAPK pathway, STAR and its analogue STARD6. A pubertal shift in genes coding for cellular cholesterol transport was observed. Increased expression of meiotic pathways coincided with the morphological onset of puberty. Puberty-related change in Ca (2+) pathway transcripts, neurosteroids, neuronal changes and signalling in redox pathways suggested a developmental-specific period of neuromorphogenesis. Several growth factors were found to increase differentially over time as the testis matured. There may be interactions between MAPK, STAR and growth factors during specific periods. In conclusion, pathways for neurogenesis, morphological pathways and several transcripts for growth factors, which have known modulating effects on steroidogenesis and gonadotropins in humans and rodents, act at specific ages and developmental stages in the boar testis. The age dependency and complexity shown for development-specific testis transcripts must be considered when selecting phenotypic parameters for genetic selection for low androstenone. The results of selection based on measurement of phenotypic maturation and androstenone (or other steroid) levels at one specific age may differ depending on the age used. More research is necessary to find the optimal phenotype to use in order to reduce the unwanted side effects.

Differential expression and co-expression gene networks reveal candidate biomarkers of boar taint in non-castrated pigs

“…Estrogen concentrations have been found to be correlated with androstenone in adipose tissue 90 , 91 . The roles of the MAPK pathway in variation of BT has recently been shown in a gene expression study on Duroc boars 92 . The authors found that upregulation of MAPK coincided with pubertal increase in androstenone and testosterone production 92 as the upregulation was observed several weeks earlier than complex morphological restructuring of testis into reproductive tissue.…”

“…The roles of the MAPK pathway in variation of BT has recently been shown in a gene expression study on Duroc boars 92 . The authors found that upregulation of MAPK coincided with pubertal increase in androstenone and testosterone production 92 as the upregulation was observed several weeks earlier than complex morphological restructuring of testis into reproductive tissue. Furthermore, proteins encoded by MAPK may regulate the Steroidogenic Acute Regulatory protein (STAR) (a cholesterol traffic regulator) and have a complex interaction with steroidgenesis (see review by Manna and Stocco 93 ).…”

“…Interestingly, STARD10 , which may play a metabolic role in sperm maturation and lipid transport 93 , was found upregulated in testis (Supplementary file 2 ) and may have other localised functions such as enrichment of lipids in milk in the mammary glands 94 . Previous works have documented the role of a subfamily of STAR in BT in testis, especially STARD6 and STAR 66 , 92 . To our knowledge this is the first time a relationship between STARD10 and BT has been reported and the association warrants further investigation of the role of STARD10 in BT.…”

“…37 summarised genes currently believed to be controlling levels of androstenone ( CYP11A1 , CYP17A , CYP21A2 , CYB5A , LHB , HSD17B7 ), androstenone metabolism ( HSD3B , SULT2A1 , SULT2B1 , TEAD3 ), phase I skatole metabolism ( CYP2A6 , CYP2E1 , CYB5A ) and phase II skatole metabolism ( SULT1A1 ). Other important genes were FMO3 72 , GSTO2 77 , COX4I1 64 , MAPK14 79 , STARD6 92 and ACOX1 77 . Thus, a high level of consistency is evident between known gene families involved in BT and the selection of candidate biomarkers in this study.…”

Lipid Metabolism is Closely Associated with Normal Testicular Growth Based on Global Transcriptome Profiles in Normal and Underdeveloped Testis of Obese Zucker (fa/fa) Rats

“…Only few studies have attempted to use a microarray as a tool to study global transcriptome analysis in testis development and sperm maturation in different species. Lervik et al [15] evaluated the developmental changes in boar testes from 12 to 27 weeks, and found that transcripts regulating steroidogenesis act at specific developmental stages. Another study identified genes with crucial roles in sperm formation, maturation and fertility, which have similar regulation across various species [16].…”