To investigate the mechanism of oridonin (ORI)-induced autophagy in prostate cancer PC-3 cells, PC-3 cells cultured in vitro were treated with ORI, and the inhibitory ratio of ORI on PC-3 cells was assayed by 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. The ultrastructural changes of the cells were observed under light microscope, scanning electron microscope (SEM), and transmission electron microscope (TEM). Acridine orange (AO) staining was used to observe the acidic vesicular organelles (AVOs). The level of autophagy-related proteins, MAP1-LC3, was detected by Western Blot, and RT-PCR was used to detect the level of mRNA of beclin 1. After ORI treatment, the proliferation of PC-3 cells was inhibited significantly in a concentration and time-dependent manner. SEM examination revealed cellular shrinkage and disappearance of surface microvilli in ORI-treated cells. Under TEM examination, the nuclei exhibited chromatin condensation and the appearance of a large number of autophagosomes with double-membrane structure in cytoplasm. AO staining showed the existence of AVOs. The expression of LC3 and the mRNA level of beclin 1 was increased by ORI. Furthermore, autophagy inhibitor 3-methyladenine reversed the increase of beclin 1 mRNA. The growth of PC-3 cells was inhibited, and autophagy was induced by ORI, indicating ORI may have a potential antitumor effect. Anat Rec,

Heat stress results in apoptosis in testicular germ cells. A small heat shock protein (hsp), hsp32, is induced by heat stress in the testis, but little is known about its definitive function in physiological processes. To clarify the underlying role of hsp32, hsp32 expression and related signals in the heat shock pathway were analysed in mouse testes and Sertoli cells after heat stress in vivo and in vitro; meanwhile, expression of hsp32 was silenced only in the Sertoli cells using three different small interfering RNAs (siRNAs) to further verify the functional role of hsp32 in Sertoli cells, and hsp32-derived carbon monoxide (CO) contents in cultured media were analysed to clarify whether hsp32-derived CO involve in the apoptosis regulation mechanisms. The results from the in vivo experiment showed that the high expression levels of hsp32 (P < 0.05) were observed whether chronic, moderate or acute, transient heat exposure. The in vitro experiment showed that acute, transient heat exposure resulted in increases in Sertoli cells apoptosis (P < 0.01), the expression of hsp32 and caspase-3 activity; hsp32-siRNA knockdown of hsp32 expression resulted in upregulated apoptosis (P < 0.01) and caspase-3 activity (P < 0.01) in the Sertoli cells and hyperthermia increases CO (P < 0.01) release by Sertoli cells. The results suggested that upregulating hsp32 in Sertoli cells inhibits caspase-3 activity and alleviates heat-induced impairments in mouse testis; hsp32-derived CO may involve in the regulation mechanism.

Hyperactivation is one of the most critical parts for fertilization. cAMP generated by soluble adenylyl cyclase (sAC) is necessary to activate sperm and is a prerequisite for sperm hyperactivation. The aim of this study is to investigate the function of sAC in hyperactivation in male rats. Four siRNAs of sAC gene were designed and were separately transformed into rat sperm using electrotransformation method. Cultured for 12 and 24 h, physiological and biochemical indexes of these sperm were analyzed, and the expressions of some hyperactivation-related genes were detected using real-time PCR. We demonstrated 26.3-30.8% and 49.1-50.5% reduction in sAC at the protein by Western blot and mRNA levels by real-time PCR, respectively. The results showed that two siRNAs, Actb-717 and Actb-4205, were the best RNAi sites for silencing sAC. The VCL (Curvilinear velocity) and ALH (Amplitude of lateral head displacement) of RNAi transfected sperm were reduced. cAMP and protein phosphorylation in RNAi transfected sperm were also decreased. The hyperactivation-related genes, such as CatSper2, LDHC and PKA, were downregulated in the sperm, which sAC was knockdown. These findings demonstrated that sAC might play a critical role in cAMP signaling in the rat sperm hyperactivation, and downregulated sAC gene might prevent the expression of these hyperactivation-ralated genes resulting in sperm dysfunction. These findings suggest that these hyperactivation-ralated genes and sAC are functionally related in sperm hyperactivation and sAC falls into an expanding group of sperm proteins that appear to be promising targets for the development of male contraceptives.

Soluble adenylyl cyclase (sAC) plays a critical role in male fertility in mammals by regulating sperm hyperactivation. We aimed to study the mechanism of sAC in this phenomenon and to explore potential target sites for male contraception. In this study, in vivo electroporation and rete testis microinjection-mediated short hairpin (sh)RNA plasmids were adopted to silence sAC gene expression in male rats. The results showed that high transfection efficiency (shRNA717, 49.0% and shRNA4205, 65.0%) was achieved by shRNA plasmids injected directly into the rete testis. When the sAC was downregulated, the cyclic adenosine monophosphate (cAMP) content and protein phosphorylation level of spermatozoa both declined with a significantly lower hyperactivation rate compared with negative controls. The highest transfection efficiency occurred at 15 d and was obviously time dependent. Bioinformatic and experimental results showed that sAC and tmAC both belong to the AC family and might have analogous functions. ShRNA717 and shRNA4205 were the best targets for the sAC gene, suggesting that they could be candidates for male contraception. Thus, it appears feasible to achieve male contraception by silencing the expression of sAC, affecting sperm hyperactivation via a cAMP-mediated signaling pathway.Rattus norvegicus, sAC, male contraception, hyperactivation, cAMP, shRNA Citation:Yu J, Zhou S, Jiang X Q, et al. Knockdown of sAC affects sperm hyperactivation by cAMP-signaling pathway in male rat (Rattus norvegicus). Chin Sci Bull, 2013, 58: 32563265,