Triptolide induces Sertoli cell apoptosis in mice via ROS/JNK-dependent activation of the mitochondrial pathway and inhibition of Nrf2-mediated antioxidant response

Abstract

Triptolide (TP), an oxygenated diterpene, has a variety of beneficial pharmacodynamic activities but its clinical applications are restricted due to severe testicular injury. This study aimed to delineate the molecular mechanisms of TP-induced testicular injury in vitro and in vivo. TP (5-50000 nmol/L) dose-dependently decreased the viability of TM4 Sertoli cells with an IC value of 669.5-269.45 nmol/L at 24 h. TP (125, 250, and 500 nmol/L) dose-dependently increased the accumulation of ROS, the phosphorylation of JNK, mitochondrial dysfunction and activation of the intrinsic apoptosis pathway in TM4 cells. These processes were attenuated by co-treatment with the antioxidant N-acetyl cysteine (NAC, 1 mmol/L). Furthermore, TP treatment inhibited the translocation of Nrf2 from cytoplasm into the nucleus as well as the expression of downstream genes NAD(P)H quinone oxidoreductase1 (NQO1), catalase (CAT) and hemeoxygenase 1 (HO-1), thus abrogating Nrf2-mediated defense mechanisms against oxidative stress. Moreover, siRNA knockdown of Nrf2 significantly potentiated TP-induced apoptosis of TM4 cells. The above results from in vitro experiments were further validated in male mice after oral administration of TP (30, 60, and 120 mg·kg·d, for 14 d), as evidenced by the detected indexes, including dose-dependently decreased SDH activity, increased MDA concentration, altered testicle histomorphology, elevated caspase-3 activation, apoptosis induction, increased phosphorylation of JNK, and decreased gene expression of NQO1, CAT and HO-1 as well as nuclear protein expression of Nrf2 in testicular tissue. Our results demonstrate that TP activates apoptosis of Sertoli cells and injury of the testis via the ROS/JNK-mediated mitochondrial-dependent apoptosis pathway and down-regulates Nrf2 activation.

Protective effect of Dioscorea zingiberensis ethanol extract on the disruption of blood–testes barrier in high‐fat diet/streptozotocin‐induced diabetic mice by upregulating ZO‐1 and Nrf2

“…The entire epididymis was removed, weighed and minced in 1 ml normal saline for 15 min at 37°C to dissociate the spermatozoa, and then, the sperm straining was carried out using a Quick Sperm Stain Kit (Nanjing Jiancheng Bioengineering Institute, China). Hereafter, the stained spermatozoa were observed with a light microscope (Ts2R, Nikon), as previously reported by Wang et al ().…”

Matrine‐Type Alkaloids Inhibit Advanced Glycation End Products Induced Reactive Oxygen Species‐Mediated Apoptosis of Aortic Endothelial Cells In Vivo and In Vitro by Targeting MKK3 and p38MAPK Signaling

“…Moreover, it was reported that c-Jun N-terminal kinase was also involved in ROS-mediated apoptosis of several types of cells. 41 Thus, further investigations of other possibly involved pathways would also be meaningful. (4) Results from this study just answered whether the MKK3/6 were phosphorylated by matrine-type alkaloids, but did not answer how.…”

Multiple signaling pathways in Sertoli cells: recent findings in spermatogenesis

“…Accumulating studies have indicated that various signaling pathways in SCs are implicated with spermatogenesis 27,28 . Until now, numerous signaling pathways have been found in Sertoli cells, including the androgensignaling pathway 29,30 , the AMP-activated protein kinase (AMPK) signaling pathway 31 , the follicle stimulating hormone (FSH)/adenylate cyclase/cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling pathway 32 , the Hippo signaling pathway 33,34 , the intergrin mediated signaling pathway 4,35 , the Janus kinase/signal transducer and activator of transcription signaling pathway 36,37 , the mitogen-activated protein kinases (MAPK) signaling pathway [38][39][40][41][42][43][44] , the nuclear factor kappa B signaling pathway 45,46 , the nitric oxide/soluble guanylyl cyclase/cyclic guanosine monophosphate/ protein kinase G signaling pathway 47,48 , the Notch signaling pathway 49 , the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3k)/AKT serine/threonine kinase (Akt) signaling pathway 50,51 , the Sonic Hedgehog signaling pathway 52,53 , the transforming growth factor-β (TGF-β)/ Smad signaling pathway 54 , and the Wnt signaling pathway 55,56 (Table 1). Among all these signaling pathways, the TGF-β/Smad, AMPK, and MAPK signaling pathways have attracted much more attentions in the past decade.…”