Loss of Ubiquitin Carboxy-Terminal Hydrolase L1 Impairs Long-Term Differentiation Competence and Metabolic Regulation in Murine Spermatogonial Stem Cells.

Whitney F Alpaugh,Rkia Dardari,Lin Su,Jeff Biernaskie,Krysta M Coyle,Timothy E Shutt,Claudia Klein,Wisoo Shin,Lin A Tang,Taylor M Goldsmith,Anna L Voigt,Iman Al Khatib,Ina Dobrinski

doi:10.3390/cells10092265

Whitney F Alpaugh, Rkia Dardari + Show 11 more

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https://doi.org/10.3390/cells10092265

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Abstract

Spermatogonia are stem and progenitor cells responsible for maintaining mammalian spermatogenesis. Preserving the balance between self-renewal of spermatogonial stem cells (SSCs) and differentiation is critical for spermatogenesis and fertility. Ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1) is highly expressed in spermatogonia of many species; however, its functional role has not been identified. Here, we aimed to understand the role of UCH-L1 in murine spermatogonia using a Uch-l1−/− mouse model. We confirmed that UCH-L1 is expressed in undifferentiated and early-differentiating spermatogonia in the post-natal mammalian testis. The Uch-l1−/− mice showed reduced testis weight and progressive degeneration of seminiferous tubules. Single-cell transcriptome analysis detected a dysregulated metabolic profile in spermatogonia of Uch-l1−/− compared to wild-type mice. Furthermore, cultured Uch-l1−/− SSCs had decreased capacity in regenerating full spermatogenesis after transplantation in vivo and accelerated oxidative phosphorylation (OXPHOS) during maintenance in vitro. Together, these results indicate that the absence of UCH-L1 impacts the maintenance of SSC homeostasis and metabolism and impacts the differentiation competence. Metabolic perturbations associated with loss of UCH-L1 appear to underlie a reduced capacity for supporting spermatogenesis and fertility with age. This work is one step further in understanding the complex regulatory circuits underlying SSC function.

Highlights

Uch-l1−/− mouse model that lacks all Ubiquitin carboxy-terminal hydrolaseL1 (UCH-L1) function, we found an increased number of degenerative seminiferous tubules in Uchl1−/− compared to Uch-l1+/+, a condition that is preceded by a dysregulation of normal metabolic transitions in undifferentiated spermatogonia, as revealed by single cell RNA sequencing analysis
UCH-L1 Is Expressed in Mouse Spermatogonia and Sertoli Cells
To examine the expression pattern of UCH-L1 in testes, immunohistochemistry was performed on PFA-fixed, paraffin-embedded sections from Uch-l1+/+ mouse testes collected at different stages of development

Summary

Introduction

Mammalian spermatogenesis is a complex, highly regulated process of cell proliferation and differentiation sustained by spermatogonial stem cells (SSCs). These cells give rise to progenitors that undergo a finite number of synchronous cell divisions before entering meiosis as a spermatocyte [1]. Considered a cell population committed to differentiation, an early subset of progenitors can de-differentiate and regain stem cell capacity, which highlights the plasticity of the undifferentiated, mitotic germ cell state [2,3]. Germ cell populations that express these markers are generally regarded as a mixed population containing SSCs among other undifferentiated spermatogonia [4,5,6]

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