The Expression Levels and Cellular Localization of Pigment Epithelium Derived Factor (PEDF) in Mouse Testis: Its Possible Involvement in the Differentiation of Spermatogonial Cells.

Noy Bagdadi,Alaa Sawaied,Mahmoud Huleihel,Eitan Lunenfeld,Ali Abumadighem

doi:10.3390/ijms22031147

Abstract

Pigment epithelium derived factor (PEDF) is a multifunctional secretory soluble glycoprotein that belongs to the serine protease inhibitor (serpin) family. It was reported to have neurotrophic, anti-angiogenic and anti-tumorigenic activity. Recently, PEDF was found in testicular peritubular cells and it was assumed to be involved in the avascular nature of seminiferous tubules. The aim of this study was to determine the cellular origin, expression levels and target cells of PEDF in testicular tissue of immature and adult mice under physiological conditions, and to explore its possible role in the process of spermatogenesis in vitro. Using immunofluorescence staining, we showed that PEDF was localized in spermatogenic cells at different stages of development as well as in the somatic cells of the testis. Its protein levels in testicular homogenates and Sertoli cells supernatant showed a significant decrease with age. PEDF receptor (PEDF-R) was localized within the seminiferous tubule cells and in the interstitial cells compartment. Its RNA expression levels showed an increase with age until 8 weeks followed by a decrease. RNA levels of PEDF-R showed the opposite trend of the protein. Addition of PEDF to cultures of isolated cells from the seminiferous tubules did not changed their proliferation rate, however, a significant increase was observed in number of meiotic/post meiotic cells at 1000 ng/mL of PEDF; indicating an in vitro differentiation effect. This study may suggest a role for PEDF in the process of spermatogenesis.

Highlights

Pigment epithelium derived factor (PEDF) is a glycoprotein that belongs to the serine protease inhibitor proteins superfamily but lost its protease inhibitory properties [1]
Our results show for the first time the localization of PEDF in mouse spermatogenic cells at different stages of development as well as in the testicular somatic cells: Sertoli and Leydig cells
Staining quantification results showed no effect of PEDF on the percentages of the VASA-positive stained cells (Figure 5C)

Summary

Introduction

Pigment epithelium derived factor (PEDF) is a glycoprotein that belongs to the serine protease inhibitor proteins superfamily but lost its protease inhibitory properties [1]. It is widely expressed in most body tissues [1,2] but the highest expression has been observed in the eye, liver, adult testis, ovaries, placenta and the pancreas [3]. Several receptors have been suggested to participate in the PEDF mechanism of action: patatin-like phospholipase domain containing 2 (PNPLA2) [11,12], laminin receptor (LR) [13], lipoprotein receptor-related protein 5 (LPR5; Wnt co-receptor) [14] and cell surface F1F0-ATP synthase [15]. PEDF binds with high affinity to PNPLA2; it is regarded as the main receptor for PEDF [16,17]

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