Combined prenatal to postnatal protein restriction augments protein quality control processes and proteolysis in the muscle of rat offspring.

Several human epidemiological and animal studies suggest that a maternal low-protein (MLP) diet affects skeletal muscle (SM) health in the offspring. However, effect of combined prenatal to postnatal protein restriction (chronic PR) and prenatal to perinatal protein restriction (PR) with postnatal rehabilitation maternal protein restriction (MPR) on protein quality control (PQC) processes and proteolysis in the offspring remains poorly understood. The current study explored the impact of chronic PR and MPR on SM protein degradation rates, chaperones, unfolded protein response (UPR), ubiquitin-proteasome system (UPS), autophagy, and apoptosis, in the adult offspring. Wistar rats were randomly assigned to a normal protein (NP; 20% casein), or low-protein (LP; 8% casein) isocaloric diets from 7 weeks prior to breeding through weaning. Offspring born to NP dams received the same diet (NP offspring) while a group of LP offspring remained on LP diet and another group was rehabilitated with NP diet (LPR offspring) from weaning for 16 weeks. LP offspring displayed lower body weight, lean mass, and myofiber cross-sectional area than NP. Furthermore, LP offspring demonstrated increased total protein degradation, urinary 3-methyl histidine, ER stress, autophagy, UPS components, proteasomal activity, muscle atrophy markers, and apoptosis-related proteins than NP. However, MPR showed little or no effect on muscle proteolysis, UPR, UPS, autophagy, apoptosis, and muscle atrophy in LPR offspring. These results indicate that exposure to chronic PR diets induces muscle atrophy and accelerates SM proteolysis via augmenting PQC processes in the offspring, while MPR shows little or no effect.

Chemopreventive Effect of Cinnamon and Its Bioactive Compounds in a Rat Model of Premalignant Prostate Carcinogenesis.

Cinnamon and its bioactive compounds inhibit prostate cancer cell proliferation in vitro. The aim of the current study was to assess the chemopreventive efficacy of cinnamon (CN) and its bioactive compounds in vivo using N-methyl-N-nitrosourea (MNU) and testosterone (T) to induce prostate carcinogenesis in male Wistar/National Institute of Nutrition rats. Cancer-induced (CI) rats (n = 10) developed prostatic hyperplasia and prostatic intraepithelial neoplasia. These histopathologic changes were diminished in CI rats fed for 4 months with diets supplemented with either CN (n = 20) or its bioactive compounds (cinnamaldehyde, n = 10 and procyanidin B2, n = 10). Androgen receptor (AR) expression was lower in the prostates of CI rats than in control, but the AR target gene, probasin, was robustly upregulated. Treatment of CI rats with CN or its bioactive compounds upregulated AR expression but inhibited the expression of the 5-alpha reductase genes (Srd5a1 and Srd5a2) and did not further increase probasin expression, suggesting blunted transcriptional activity of AR due to the limited availability of dihydrotestosterone. MNU+T induced an altered oxidant status in rat prostate, which was reflected by an increase in lipid peroxidation and DNA oxidation. These changes were completely or partially corrected by treatment with CN or the bioactive compounds. CN and its active components increased the activity of the apoptotic enzymes caspase-8 and caspase-3 in the prostates of CI rats. In conclusion, our data demonstrate that CN and its bioactive compounds have inhibitory effects on premalignant prostate lesions induced by MNU + T and, therefore, may be considered for the chemoprevention of prostate cancer. PREVENTION RELEVANCE: The research work presented in this article demonstrates the chemopreventive efficacy of CN and its bioactive compounds in a rat model of premalignant prostate cancer.

Disrupted expression of genes essential for skeletal muscle fibre integrity and energy metabolism in Vitamin D deficient rats.

Vitamin D, a secosteroid that regulates mineral homeostasis via its actions in intestine, bone, kidneys and parathyroid glands, has many other target tissues, including skeletal muscle. In the present study, we used rats to examine if diet-induced vitamin D deficiency or insufficiency altered protein synthesis in muscle via the mTOR pathway, and impaired skeletal muscle quality by changing expression of genes needed for its function. Vitamin D deficiency resulted in reduced levels of phosphorylated mTOR, and suppressed mTOR-dependent phosphorylation of 4E-BP1 and p70-S6K, implying a decrease in activity of the protein synthesis machinery. These changes were coupled with up regulation of genes that are negative regulators of muscle growth (Fbxo32 & Trim63), leading to a net loss of skeletal muscle mass. Vitamin D deficiency or insufficiency also led to a decrease in expression of both myosin and actin-associated proteins (Myh1, Myh2, Myh7, Tnnc1& Tnnt1), which are essential for generation of the mechanical force needed for muscle contraction. We also detected a decrease in expression of glycolytic and oxidative enzyme genes (Hk2, Pfkm, Cs, Pdk4 & ßHad) and transcriptional coactivator genes (Ppargc-1α & Ppargc-1ß) which indicate a low oxidative capacity of skeletal muscle in the vitamin D deficient state. Furthermore, decreased citrate synthase activity corroborates a decrease in mitochondrial density and aerobic capacity of the muscle. In conclusion, our study demonstrates that chronic vitamin D deficiency or insufficiency reduced the size of skeletal muscle fibres, altered their composition, and decreased their oxidative potential. Most of the changes observed were reversible, either partially or completely, by restoring vitamin D to the diet of the deficient rats.

Cytotoxicity and Proteasome Inhibition by Alkaloid Extract from Murraya koenigii Leaves in Breast Cancer Cells-Molecular Docking Studies.

Murraya koenigii (curry tree) leaves are rich in bioactive compounds such as flavonoids, alkaloids, and coumarins. Alkaloids from M. koenigii leaves have antianalgesic, antiulcerogenic, antiobesity, and antitumor activities. In this study, we tested the cytotoxic and proteasome-inhibitory potential of a total alkaloid extract (TAE) from M. koenigii leaves in the breast cancer cell line MDA-MB-231. The TAE decreased cell viability with an IC50 of 14.4 µg/mL and altered growth kinetics of breast cancer cells. TAE (32 µg/mL) arrested cells (35%) in the "S" phase of the cell cycle and induced apoptosis. The 26S proteasome, a multicatalytic protease complex, promotes tumor cell proliferation and protects tumor cells from apoptosis. The TAE and mahanine, a carbazole alkaloid present in M. koenigii leaves, preferentially inhibited the trypsin-like, but not the chymotrypsin-like proteolytic activity of the proteasome with an IC50 of 162 µg/mL and 287 µM, respectively. In silico analysis of 26 compounds from M. koenigii leaves revealed significant docking scores for mahanine and two other carbazole alkaloids with the ß2 and ß5 subunits of the catalytic 20S proteasome. Taken together, this study demonstrates that inhibition of the proteasome is an important biological activity of M. koenigii alkaloids, which may lead to cancer cell death.

In Vivo Inhibition of Proteasome Activity and Tumour Growth by Murraya koenigii Leaf Extract in Breast Cancer Xenografts and by Its Active Flavonoids in Breast Cancer Cells.

Inhibition of the 26S proteasome is an attractive approach for anticancer therapy. Proteasome inhibitors are known to selectively target cancer cells and make them more sensitive to chemotherapeutic agents. Murraya koenigii is a medicinally important herb of Asian origin and a rich source of bioactive compounds such as flavonoids and alkaloids. In the present study, we investigated the proteasome inhibitory and apoptotic effect of M. koenigii leaf extract in vivo in a xenograft tumor mouse model, and also assessed the toxicity if any in normal mice. M. koenigii extract did not lead to any toxicity in mice. Analysis of extract revealed the presence of flavonoid compounds which act as proteasome inhibitors. Quercetin treatment led to the decrease in the cell viability and arrest of cells in G2/M phase. Quercetin, Apigenin, Kaempferol and Rutin; flavonoids present in the leaf extract, dose-dependently inhibited the endogenous 26S proteasome activity in MDA-MB-231 cells. Reduction in tumor growth was associated with a decrease in proteasomal enzyme activities in the treated groups. Increased caspase-3 activity and TUNEL-positive cells indicated enhanced apoptosis with Murraya leaf extract treatment. Decreased expression of angiogenic and anti-apoptotic gene markers is indicative of inhibition of angiogenesis and promotion of apoptosis in the leaf extract treated tumors.