A Novel Model Using AAV9-Cre to Knockout Adult Leydig Cell Gene Expression Reveals a Physiological Role of Glucocorticoid Receptor Signalling in Leydig Cell Function

Abstract

Glucocorticoids are steroids involved in key physiological processes such as development, metabolism, inflammatory and stress responses and are mostly used exogenously as medications to treat various inflammation-based conditions. They act via the glucocorticoid receptor (GR) expressed in most cells. Exogenous glucocorticoids can negatively impact the function of the Leydig cells in the testis, leading to decreased androgen production. However, endogenous glucocorticoids are produced by the adrenal and within the testis, but whether their action on GR in Leydig cells regulates steroidogenesis is unknown. This study aimed to define the role of endogenous GR signalling in adult Leydig cells. We developed and compared two models; an inducible Cre transgene driven by expression of the Cyp17a1 steroidogenic gene (Cyp17-iCre) that depletes GR during development and a viral vector-driven Cre (AAV9-Cre) to deplete GR in adulthood. The delivery of AAV9-Cre ablated GR in adult mouse Leydig cells depleted Leydig cell GR more efficiently than the Cyp17-iCre model. Importantly, adult depletion of GR in Leydig cells caused reduced expression of luteinising hormone receptor (Lhcgr) and of steroidogenic enzymes required for normal androgen production. These findings reveal that Leydig cell GR signalling plays a physiological role in the testis and highlight that a normal balance of glucocorticoid activity in the testis is important for steroidogenesis.

Steroid hormone signaling: multifaceted support of testicular function

“…Sertoli-specific Gr deletion in mice had a limited impact on fertility but did reduce Sertoli cell and spermatocyte numbers (Hazra et al, 2014). A 50% reduction of GR in Leydig cells using AAV9-Cre disrupted steroidogenesis (Gannon et al, 2022), suggesting a role for GR in Leydig cell function. Rat adrenalectomy studies showed decreased sperm counts were partially restored by dexamethasone, but not sperm morphology (Silva et al, 2014).…”

Unlocking Genetic Mysteries during the Epic Sperm Journey toward Fertilization: Further Expanding Cre Mouse Lines

“…Annalucia et al characterized the ability of viral vectors, including adenovirus, lentivirus, and adeno-associated virus (AAV), to deliver exogenous genes targeting Leydig cells in adult mouse testes and determined that AAV serotype 9 (AAV9) + neuraminidase transported the transgenes efficiently [142]. Moreover, AAV9-driven Cre was generated by the Diane group to delete endogenous glucocorticoid receptors in adult Leydig cells; the silencing efficiency of AAV9-Cre to AR was 48% 7 days after injection, which was higher than that of the Cyp17a1-iCre transgenic approach (28%) [143]. The AAV9 virus was found to infect germ cells of the testes from 3-week mice [144], possibly because these testes are not fully developed in immature mice, and the blood-testis barrier is not fully established.…”

Glucocorticoids improve sperm performance in physiological and pathological conditions: their role in sperm fight/flight response

“…Detectable GR expression has been described in several key testicular cell types, including the somatic Sertoli, Leydig, and peritubular cells, as well as early germ cell populations [ 10 - 12 ]. The specific role of GR within most of these cell types remains unknown.…”