Adenosine-A Regulator of Human Testicular Peritubular Cells

Extracellular purines, in particular ATP and adenosine, are regulators of physiological and pathophysiological processes throughout the human body. Roles in the human testis are emerging and include actions on peritubular cells, which form the wall of seminiferous tubules.

Here, we examined adenosine-evoked consequences in human testicular peritubular cells (HTPCs).

HTPCs were isolated from testicular samples, cultured and examined. The ability of HTPCs to generate extracellular adenosine was investigated. Acute actions of adenosine were evaluated by monitoring intracellular Ca²⁺ levels and signaling pathways. Studies with selective adenosine receptor agonists and knockdown of the ADORA2B receptor were performed. Transcriptional and translational changes evoked by adenosine were evaluated using scRNA-seq and proteomic studies. Regulation of ADORA2B by the synthetic glucocorticoid dexamethasone and 5⍺-dihydrotestosterone were analyzed by qPCR.

HTPCs metabolized extracellular ATP and generated adenosine. They express the required enzymatic machinery and functional adenosine receptors (ADORA1, ADORA2A, and ADORA2B), which likely mediated adenosine action on MAPK pathways and intracellular Ca²⁺ transients. Proteomic studies revealed that exposure to adenosine for 24 h affected the abundance of 38 proteins. Among others, IL33 and StAR were strongly increased. Agonist- and siRNA-mediated knockdown studies identified ADORA2B as a key mediator of IL33 upregulation. StAR upregulation was accompanied by increased pregnenolone formation. The proteomic changes were confirmed by scRNA-seq, which revealed additional transcriptional remodeling, including HIF1A induction and enrichment of pathways linked to cell communication, migration and inflammation. Dexamethasone reduced ADORA2B levels, implying plasticity of this member of the purinergic signaling system.

HTPCs generate extracellular adenosine and respond to adenosine via receptor-mediated signaling, transcriptional remodeling, inflammatory signaling and steroidogenesis. If transferable to the in situ situation, adenosine is a multifunctional regulator of the peritubular compartment, involved in testicular homeostasis and male (in)fertility.