Region-specific localization of NOS isoforms and NADPH-diaphorase activity in the intratesticular and excurrent duct systems of adult domestic cats (Felis catus)

The effects of S-nitrosylation-induced PPARγ/SFRP5 pathway inhibition on the conversion of non-alcoholic fatty liver to non-alcoholic steatohepatitis

Background

Peroxisome proliferators-activated receptors γ (PPARγ) and secreted frizzled related protein 5 (SFRP5) are abnormally expressed in liver cells. But their role in the transformation of non-alcoholic fatty liver (NAFL) to non-alcoholic steatohepatitis (NASH) remains to be studied. We aimed to explore the role of S-nitrosylation (SNO) in the conversion of NAFL to NASH via the peroxisome PPARγ/SFRP5 pathway.

Methods

A normal diet and methionine-choline deficient diet were used to construct the NAFL and NASH mouse models, respectively. The differences between the SNO of PPARγ in both models were measured by irreversible biotinylation. Quantitative reverse transcription PCR (qRT-PCR) and Western blotting were used to detect the effect of SNO on the expression of PPARγ messageRNA (mRNA) and protein in L02 hepatocytes. Nubiscan software, luciferase reporter gene, and chromatin immunoprecipitation assay (CHIP) were used to verify the targeting relationship between PPAR and SFRP5. The expression of tumor necrosis factor α (TNFα), interleukin-1β (IL-1β), and interleukin-6 (IL-6), which are indicators for the activation of Kupffer cells, were determined by enzyme linked immunosorbent assay (ELISA) after co-cultivation of L02 hepatocytes and Kupffer macrophages, as well as the exogenous regulation of SNO, PPARγ, and SFRP5 in hepatic L02 cells.

Results

The NAFL and NASH mouse models were successfully constructed, and the level of PPARγ SNO in the NAFL model was significantly lower than the NASH model (P<0.05). The level of PPARγ was significantly downregulated after increasing the SNO of L02 cells, respectively (P<0.05). Nubiscan software and CHIP confirmed that PPARγ could bind to the promoter region of SFRP5 (P<0.05). Overexpression of PPARγ and SFRP5 could significantly downregulate the expression of TNFα, IL-1β, and IL-6 (P<0.05) correspondingly, while increasing the SNO level of L02 cells could restore the expression levels of TNFα, IL-1β, and IL-6.

Conclusions

SNO promoted the activation of macrophage Kupffer cells by inhibiting the PPARγ/SFRP5 pathway in L02 hepatocytes, thereby promoting the conversion of NAFL into NASH.

The Roles of NO and H2S in Sperm Biology: Recent Advances and New Perspectives

After being historically considered as noxious agents, nitric oxide (NO) and hydrogen sulfide (H2S) are now listed as gasotransmitters, gaseous molecules that play a key role in a variety of cellular functions. Both NO and H2S are endogenously produced, enzymatically or non-enzymatically, and interact with each other in a range of cells and tissues. In spite of the great advances achieved in recent decades in other biological systems, knowledge about H2S function and interactions with NO in sperm biology is in its infancy. Here, we aim to provide an update on the importance of these molecules in the physiology of the male gamete. Special emphasis is given to the most recent advances in the metabolism, mechanisms of action, and effects (both physiological and pathophysiological) of these gasotransmitters. This manuscript also illustrates the physiological implications of NO and H2S observed in other cell types, which might be important for sperm function. The relevance of these gasotransmitters to several signaling pathways within sperm cells highlights their potential use for the improvement and successful application of assisted reproductive technologies.

The expression and localization of Toll-like receptors 2, 4, 5 and 9 in the epididymis and vas deferens of a adult tom cats

Toll-like receptors (TLRs) are important molecules, which provide protection against infections of the reproductive tract. This study demonstrates for the first time the expression and localization patterns of TLRs in the caput, corpus and cauda segments of the epididymal duct (ED) and the vas deferens (VD) of adult domestic cats using immunohistochemistry and western blotting. While immunoblot analyses revealed relatively similar protein levels for TLRs 2, 4, 5, and 9 in three segments of the ED, the protein levels of TLR2 and TLR4 in the VD were found to be significantly higher than those measured in the ED segments (P < 0.05). On the other hand, immunostaining showed that TLRs exhibited regional- and cell-specific localization patterns. TLR2 and TLR5 were immunolocalized to the nucleus and cytoplasm of the principal cells in all ducts. TLR4 was restricted to the stereocilia, and TLR9 was located in the cytoplasm of the principal cells. Narrow cells displayed positive immunoreactions for TLR4 and TLR5. The basal cells of the different ED segments were positive for all four TLRs. TLR2, TLR5 and TLR9 were detected in the cytoplasmic droplets of the spermatozoa. TLR4 and TLR9 were detected along the entire length of the sperm tail, whilst TLR2 and TLR5 were absent in the midpiece. TLR2 and TLR5 were also detected in the equatorial segment of the sperm head. These results suggest that TLR2, TLR4, TLR5 and TLR9 are important not only for the protection of the ED, VD and spermatozoa but also for the maturation and storage of spermatozoa in the ED and VD, respectively.