Effects of Azgp1-/-on mammary gland, adipose tissue and liver gene expression and milk lipid composition in lactating mice

The Therapeutic Potential of Zinc-Alpha2-Glycoprotein (AZGP1) in Fibrotic Kidney Disease

Chronic kidney disease (CKD) is characterized by a long-term loss of kidney function and, in most cases, by progressive fibrosis. Zinc-alpha2-glycoprotein (AZGP1) is a secreted protein, which is expressed in many different tissues and has been associated with a variety of functions. In a previous study, we have shown in cell culture and in AZGP1 deficient mice that AZGP1 has protective anti-fibrotic effects. In the present study, we tested the therapeutic potential of an experimental increase in AZGP1 using two different strategies. (1) C57Bl/6J mice were treated systemically with recombinant AZGP1, and (2) a transgenic mouse strain was generated to overexpress AZGP1 conditionally in proximal tubular cells. Mice underwent unilateral uretic obstruction as a pro-fibrotic kidney stress model, and kidneys were examined after 14 days. Recombinant AZGP1 treatment was accompanied by better preservation of tubular integrity, reduced collagen deposition, and lower expression of injury and fibrosis markers. Weaker but similar tendencies were observed in transgenic AZGP1 overexpressing mice. Higher AZGP1 levels led to a significant reduction in stress-induced accumulation of tubular lipid droplets, which was paralleled by improved expression of key players in lipid metabolism and fatty acid oxidation. Together these data show beneficial effects of elevated AZGP1 levels in fibrotic kidney disease and highlight a novel link to tubular cell lipid metabolism, which might open up new opportunities for CKD treatment.

Zinc and the Innovative Zinc-α2-Glycoprotein Adipokine Play an Important Role in Lipid Metabolism: A Critical Review

Numerous studies indicate that zinc and the new zinc-related adipokine, zinc-α2-glycoprotein (ZAG), are involved in lipid metabolism. Excess body fat lowers blood concentrations of Zn and ZAG, leading not only to the development of obesity but also to other components of the metabolic syndrome. Zinc homeostasis disorders in the body negatively affect the lipid profile and cytokine secretion. Zinc appears to be a very important ZAG homeostasis regulator. The physiological effects of ZAG are related to lipid metabolism, but studies show that ZAG also affects glucose metabolism and is linked to insulin resistance. ZAG has a zinc binding site in its structure, which may indicate that ZAG mediates the effect of zinc on lipid metabolism. The review aimed to verify the available studies on the effects of zinc and ZAG on lipid metabolism. A literature review within the scope of this research area was conducted using articles available in PubMed (including MEDLINE), Web of Science and Cochrane Library databases. An analysis of available studies has shown that zinc improves hepatic lipid metabolism and has an impact on the lipid profile. Numerous studies have found that zinc supplementation in overweight individuals significantly reduced blood levels of total cholesterol, LDL (Low-density lipoprotein)cholesterol and triglycerides, potentially reducing cardiovascular morbidity and mortality. Some results also indicate that it increases HDL-C (High-density lipoprotein) cholesterol levels. ZAG has been shown to play a significant role in reducing obesity and improving insulin sensitivity, both in experimental animal model studies and in human studies. Furthermore, ZAG at physiologically relevant concentrations increases the release of adiponectin from human adipocytes. In addition, ZAG has been shown to inhibit in vitro leptin production. Further studies are needed to provide more data on the role of zinc and zinc-α2-glycoprotein.

Nitrogen Forms Alter Triterpenoid Accumulation and Related Gene Expression in Cyclocarya paliurus (Batalin) Iljinsk. Seedlings

Cyclocarya paliurus (Batalin) Iljinsk. is a multiple function tree species distributed in subtropical areas, and its leaves have been used in medicine and nutraceutical foods in China. However, little information on the effects of nitrogen (N) forms and ratios on growth and secondary metabolite accumulation is available for C. paliurus. The impact of five NO3−/NH4+ ratios on biomass production, triterpenoid accumulation and related gene expression in C. paliurus seedlings was evaluated at the middle N nutrition supply. Significant differences in seedling growth, triterpenoid accumulation and relative gene expression were observed among the different NO3−/NH4+ ratio treatments. The highest triterpenoid content was achieved in a sole NO3− or NH4+ nutrition, while the mixed N nutrition with equal ratio of NO3− to NH4+ produced the highest biomass production in the seedlings. However, the highest triterpenoid accumulation was achieved at the treatment with the ratio of NO3−/NH4+ = 2.33. Therefore, the mixed N nutrition of NO3− and NH4+ was beneficial to the triterpenoid accumulation per plant. The relative expression of seven genes that are involved in triterpenoid biosynthesis were all up-regulated under the sole NH4+ or NO3− nutrition conditions, and significantly positive correlations between triterpenoid content and relative gene expression of key enzymes were detected in the leaves. Our results indicated that NO3− is the N nutrition preferred by C. paliurus, but the mixture of NO3− and NH4+ at an appropriate ratio would improve the leaf triterpenoid yield per area.