Identification of PDCL2 as a candidate marker in Sertoli cell-only syndrome by chromatin immunoprecipitation-sequencing and bioinformatics analysis

Sertoli cell-only syndrome (SCOS) or germ cell aplasia is one of the most serious histopathological subtypes within the scope of non-obstructive azoospermia (NOA). Understanding the molecular mechanism of SCOS and identifying new non-invasive markers for clinical application is crucial to guide proper sperm procurement and avoid unnecessary interventions. This study sought to identify the differentially expressed genes (DEGs) of SCOS by using gene sequencing identity and verify the key marker genes to provide basic data for subsequent research on SCOS.A total of 50 testicular samples were collected in this study from 25 patients with SCOS and 25 patients with normal spermatogenesis. In total, 5 pairs of testis samples were used for the RNA-sequencing (RNA-seq). We identified the DEGs between the SCOS and normal spermatogenesis patients and conducted a Gene Ontology (GO) analysis and a Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The expression of the main target gene phosducin-like 2 (PDCL2) was examined by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC).In total, 3,133 upregulated DEGs and 1,406 downregulated DEGs were identified by the RNA-seq. The highly enriched processes involved in spermatogenesis included the mitotic cell cycle, cell cycle, and oocyte maturation. The expression of PDCL2 was verified as a downregulation marker in SCOS by qRT-PCR and IHC.This study identified the DEGs of SCOS, and the bioinformatics analysis results identified the potential target key genes and pathways for SCOS. PDCL2 is a key gene involved in SCOS and may serve as a non-invasive downregulation marker of SCOS.