Stem Leydig Cell Differentiation: Gene Expression During Development of the Adult Rat Population of Leydig Cells1

Abstract

Leydig cells are the testosterone-producing cells in the adult male. Adult Leydig cells (ALCs) develop from stem Leydig cells (SLCs) through at least two intermediate cells, progenitor Leydig cells (PLCs) and immature Leydig cells (ILCs). Microarray gene expression was used to identify the transcriptional changes that occur with the differentiation of SLCs to PLCs and, thus, with the entry of SLCs into the Leydig cell lineage; to comprehensively examine differentiation through the development of ALCs; and to relate the pattern of gene expression in SLCs to that in a well-established stem cell, bone marrow stem cells (BSCs). We show that the pattern of gene expression by SLCs was more similar to the expression by BSCs, an established stem cell outside the male reproductive tract, than to any of the cells in the Leydig cell developmental lineage. These results indicated that the SLCs have many of the molecular characteristics of other stem cells. Pathway analysis indicated that development of Leydig cells from SLCs to PLCs was associated with decreased expression of genes related to adhesion and increased expression of genes related to steroidogenesis. Gene expression changes between PLCs and ILCs and between ILCs and ALCs were relatively minimal, suggesting that these cells are highly similar. In contrast, gene expression changes between SLCs and ALCs were quite distinct.

Regulation of seminiferous tubule-associated stem Leydig cells in adult rat testes

“…CD51 and p75NTR also are cell surface proteins whose expressions were found to overlap with that of nestin in the neonatal mouse testis (11). By reanalysis of an earlier array study (13), we also identified a number of cell surface proteins whose mRNAs were highly expressed by stem cells but turned off with the transit of these cells to progenitor Leydig cells.…”

“…In an earlier study, we had conducted microarray analysis of gene expression during the differentiation of neonatal stem Leydig cells to cells that entered the Leydig cell lineage as progenitor Leydig cells (13). The significantly up-regulated or down-regulated genes for signaling molecules and receptors were among those in which we took particular interest.…”

Identification of Leydig cell-specific mRNA transcripts in the adult rat testis

“…Microarray analysis of transcripts from isolated adult rat Leydig cells by Stanley et al (2011) showed the presence of 16 713 specific species (not allowing for duplicates on Leydig cell mRNA transcripts the arrays). Most of these transcripts will not be unique to the Leydig cells, but a degree of specificity can be estimated by determining the relative enrichment of these transcripts in comparison to our control wholetestis arrays.…”

“…This is consistent with a predominant Leydig cell expression of transcripts listed in Table 1. Stanley et al (2011) also identified 42 genes upregulated during Leydig cell development and, of these genes, 17 are also included in Supplementary Table 2, including eight of the top 11 genes we identified. When the same 42 genes identified by Stanley (2011) were compared with the full list of transcripts significantly altered by EDS (Supplementary Table 1), the number of matches increased to 23 although most of the additional six matches showed either low expression or complex changes in expression after EDS treatment (Supplementary Table 3, see section on supplementary data given at the end of this article).…”

“…To understand the role of the Leydig cell, a comprehensive list of transcripts strongly and uniquely expressed in these cells is a prerequisite. Previous studies have generated lists of transcripts expressed in Leydig cells by microarray analysis of isolated cells (Stanley et al 2011). While these lists are of considerable value, most of the transcripts present are expressed in multiple cell types, so that identifying Leydig cell-specific transcripts can be complex.…”