Interleukin-34, a Novel Paracrine/Autocrine Factor in Mouse Testis, and Its Possible Role in the Development of Spermatogonial Cells In Vitro.

Alaa Sawaied,Eitan Lunenfeld,Mahmoud Huleihel

doi:10.3390/ijms21218143

Alaa Sawaied, Eitan Lunenfeld + Show 1 more

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https://doi.org/10.3390/ijms21218143

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Abstract

Spermatogenesis is the process of spermatogonial stem cell (SSC) proliferation and differentiation to generate sperm. This process is regulated by cell–cell interactions between Sertoli cells and developing SSCs by autocrine/paracrine and endocrine factors. It is also affected by cells in the interstitial compartment, such as Leydig cells and peritubular cells. Here, we demonstrate, for the first time, the presence of interleukin-34 (IL-34) in Leydig, Sertoli, and peritubular cells and in the premeiotic, meiotic, and postmeiotic cells. Its receptor, colony-stimulating factor-1 (CSF-1), has already been demonstrated in Leydig, Sertoli, premeiotic, and meiotic cells. IL-34 was detected in testicular homogenates and Sertoli cell-conditioned media, and was affected by mouse age. We showed that the addition of IL-34 in vitro to isolated cells from the seminiferous tubules of 7-day-old mice, using the methylcellulose culture system (MCS), increased the percentages and expression of the premeiotic cells (VASA), the meiotic cells (BOULE), and the meiotic/postmeiotic cells (ACROSIN) after four weeks of culture, when examined by immunofluorescence staining (IF) and qPCR analysis. It is possible to suggest that IL-34 is a novel paracrine/autocrine factor involved in the development of spermatogenesis. This factor may be used in future therapeutic strategies for the treatment of male infertility.

Highlights

Spermatogenesis is a complicated process that includes proliferation and differentiation of spermatogonial stem cells (SSCs) to generate sperm [1,2,3,4,5,6]
Our results demonstrated that IL-34 is present in different cells in the seminiferous tubules and in the interstitial compartment along all examined ages (Figure 1A)
Using double immunofluorescence staining (IF) staining for isolated testicular somatic cells (Sertoli, peritubular, and Leydig cells), from 6-week-old mice and IL-34, we demonstrated that all the examined cells were positively stained to IL-34 (Figure 1B)

Summary

Introduction

Spermatogenesis is a complicated process that includes proliferation and differentiation of spermatogonial stem cells (SSCs) to generate sperm [1,2,3,4,5,6]. Cells of each stage express specific markers, such as VASA, PLZF, and SALL4 for the premeiotic stage, BOULE, CREM-1, and ACROSIN for the meiotic stage, and ACROSIN and PROTAMINE for the postmeiotic stage [3,4,7,8,9,10,11] This process is under the regulation of endocrine and testicular autocrine/paracrine factors [1,4,5]. Testicular somatic cells such as Leydig cells, peritubular cells, and Sertoli cells produce various autocrine/paracrine factors that are involved in the regulation of spermatogenesis such as colony-stimulating factor-1 (CSF-1), stem cell factor (SCF), glial cell line-derived neurotrophic factor (GDNF), and others [1,2,3,4,12,13,14,15] Receptors for these factors were demonstrated on spermatogonial cells [12,16,17,18]

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