Metabolic transitions define spermatogonial stem cell maturation

• Published in: Human reproduction (Oxford) 2022-08, Vol.37 (9), p.2095-2112
• Main Authors: Voigt, A L, Dardari, R, Su, L, Lara, N L M, Sinha, S, Jaffer, A, Munyoki, S K, Alpaugh, W, Dufour, A, Biernaskie, J, Orwig, K E, Dobrinski, I
• Format: Article
• Language: English
• Subjects: Adult; Animals; Child, Preschool; Humans; Infertility - metabolism; Male; Mammals; Mice; Original; Proteomics; Spermatogonia; Stem Cells; Swine; Testis - metabolism
• ISSN: 0268-1161; 1460-2350
• DOI: 10.1093/humrep/deac157

Abstract STUDY QUESTION Do spermatogonia, including spermatogonial stem cells (SSCs), undergo metabolic changes during prepubertal development? SUMMARY ANSWER Here, we show that the metabolic phenotype of prepubertal human spermatogonia is distinct from that of adult spermatogonia and that SSC development is characterized by distinct metabolic transitions from oxidative phosphorylation (OXPHOS) to anaerobic metabolism. WHAT IS KNOWN ALREADY Maintenance of both mouse and human adult SSCs relies on glycolysis, while embryonic SSC precursors, primordial germ cells (PGCs), exhibit an elevated dependence on OXPHOS. Neonatal porcine SSC precursors reportedly initiate a transition to an adult SSC metabolic phenotype at 2 months of development. However, when and if such a metabolic transition occurs in humans is ambiguous. STUDY DESIGN, SIZE, DURATION To address our research questions: (i) we performed a meta-analysis of publicly available and newly generated (current study) single-cell RNA sequencing (scRNA-Seq) datasets in order to establish a roadmap of SSC metabolic development from embryonic stages (embryonic week 6) to adulthood in humans (25 years of age) with a total of ten groups; (ii) in parallel, we analyzed single-cell RNA sequencing datasets of isolated pup (n = 3) and adult (n = 2) murine spermatogonia to determine whether a similar metabolic switch occurs; and (iii) we characterized the mechanisms that regulate these metabolic transitions during SSC maturation by conducting quantitative proteomic analysis using two different ages of prepubertal pig spermatogonia as a model, each with four independently collected cell populations. PARTICIPANTS/MATERIALS, SETTING, METHODS Single testicular cells collected from 1-year, 2-year and 7-year-old human males and sorted spermatogonia isolated from 6- to 8-day (n = 3) and 4-month (n = 2) old mice were subjected to scRNA-Seq. The human sequences were individually processed and then merged with the publicly available datasets for a meta-analysis using Seurat V4 package. We then performed a pairwise differential gene expression analysis between groups of age, followed by pathways enrichment analysis using gene set enrichment analysis (cutoff of false discovery rate < 0.05). The sequences from mice were subjected to a similar workflow as described for humans. Early (1-week-old) and late (8-week-old) prepubertal pig spermatogonia were analyzed to reveal underlying cellular mechanisms of the metabolic shift using im