The Molecular Signature of Human Testicular Peritubular Cells Revealed by Single-Cell Analysis

Abstract

Peritubular cells of the human testis form a small compartment surrounding the seminiferous tubules. They are crucial for sperm transport, and they emerge as contributors to the spermatogonial stem cell niche. They are among the least known cell types of the human body. We employed single-cell RNA sequencing of cultured human testicular peritubular cells (HTPCs), which had been isolated from testicular samples of donors with normal spermatogenesis. The significant overlap between our results and recently published ex vivo data indicates that HTPCs are a highly adequate cellular model to define and study these cells. Thus, based on the expression of several markers, HTPCs can be classified as testicular smooth muscle cells. Small differences between the in vivo/in vitro expressed genes may be due to cellular plasticity. Plasticity was also shown upon addition of FCS to the culture medium. Based on transcriptome similarities, four cellular states were identified. Further analyses confirmed the presence of known stem cell niche-relevant factors (e.g., GDNF) and identified unknown functions, e.g., the ability to produce retinoic acid. Therefore, HTPCs allow us to define the signature(s) and delineate the functions of human testicular peritubular cells. The data may also serve as a resource for future studies to better understand male (in)fertility.

Prolonged exposure to dexamethasone alters the proteome and cellular phenotype of human testicular peritubular cells

“…Human testicular peritubular cells (HTPCs) are contractile smooth muscle cells [1], which together with extracellular matrix (ECM) form the peritubular compartment within the testis. This region is located between the compartment, in which spermatogenesis takes place, and the interstitial areas, which contain Leydig cells and blood vessels [2–4].…”

“…Their localization at the “interphase” between the testosterone‐producing Leydig cells and Sertoli cells/germ cells enables them to interact with both, the tubular and the interstitial compartments [5]. Contractions of HTPCs cause sperm transport in the testis [6], but these cells also participate in testicular immune surveillance, are important for the spermatogonial stem cell niche and are involved in paracrine signaling [1, 7–9]. Of note, these human testicular cells can be isolated and studied in vitro, as they largely retain their in situ phenotype [1], thereby opening a valuable research opportunity of the male gonad [10].…”

“…Contractions of HTPCs cause sperm transport in the testis [6], but these cells also participate in testicular immune surveillance, are important for the spermatogonial stem cell niche and are involved in paracrine signaling [1, 7–9]. Of note, these human testicular cells can be isolated and studied in vitro, as they largely retain their in situ phenotype [1], thereby opening a valuable research opportunity of the male gonad [10]. Androgen and glucocorticoid receptor (GR, encoded by NR3C1 ) were unveiled in HTPCs in situ and in vitro [11–13] and their expression implies regulation by steroids.…”

“…be isolated and studied in vitro, as they largely retain their in situ phenotype [1], thereby opening a valuable research opportunity of the male gonad [10]. Androgen and glucocorticoid receptor (GR, encoded by NR3C1) were unveiled in HTPCs in situ and in vitro [11][12][13] and their expression implies regulation by steroids.…”

Connecting the Dots: N6‐Methyladenosine (m6A) Modification in Spermatogenesis

“…Single-cell sequencing (scRNA-seq) techniques allow us to visualize the expression profile of m 6 A catalase enzymes in different germ cells. [24][25][26][27][28][29][30][31] It has the potential to provide a comprehensive understanding of these proteins during spermatogenesis. This review aims to summarize and discuss recent findings on m 6 A and spermatogenesis by examining the expression and interrelationship of catalase enzymes in germ cells to provide new insights into the role of m 6 A modifications in spermatogenesis.…”