Proline hydroxylation linked to Akt activation

Akt: a key transducer in cancer

Growth factor signaling plays a pivotal role in diverse biological functions, such as cell growth, apoptosis, senescence, and migration and its deregulation has been linked to various human diseases. Akt kinase is a central player transmitting extracellular clues to various cellular compartments, in turn executing these biological processes. Since the discovery of Akt three decades ago, the tremendous progress towards identifying its upstream regulators and downstream effectors and its roles in cancer has been made, offering novel paradigms and therapeutic strategies for targeting human diseases and cancers with deregulated Akt activation. Unraveling the molecular mechanisms for Akt signaling networks paves the way for developing selective inhibitors targeting Akt and its signaling regulation for the management of human diseases including cancer.

Hydroxyproline in animal metabolism, nutrition, and cell signaling

trans-4-Hydroxy-L-proline is highly abundant in collagen (accounting for about one-third of body proteins in humans and other animals). This imino acid (loosely called amino acid) and its minor analogue trans-3-hydroxy-L-proline in their ratio of approximately 100:1 are formed from the post-translational hydroxylation of proteins (primarily collagen and, to a much lesser extent, non-collagen proteins). Besides their structural and physiological significance in the connective tissue, both trans-4-hydroxy-L-proline and trans-3-hydroxy-L-proline can scavenge reactive oxygen species and have both structural and physiological significance in animals. The formation of trans-4-hydroxy-L-proline residues in protein kinases B and DYRK1A, eukaryotic elongation factor 2 activity, and hypoxia-inducible transcription factor plays an important role in regulating their phosphorylation and catalytic activation as well as cell signaling in animal cells. These biochemical events contribute to the modulation of cell metabolism, growth, development, responses to nutritional and physiological changes (e.g., dietary protein intake and hypoxia), and survival. Milk, meat, skin hydrolysates, and blood, as well as whole-body collagen degradation provide a large amount of trans-4-hydroxy-L-proline. In animals, most (nearly 90%) of the collagen-derived trans-4-hydroxy-L-proline is catabolized to glycine via the trans-4-hydroxy-L-proline oxidase pathway, and trans-3-hydroxy-L-proline is degraded via the trans-3-hydroxy-L-proline dehydratase pathway to ornithine and glutamate, thereby conserving dietary and endogenously synthesized proline and arginine. Supplementing trans-4-hydroxy-L-proline or its small peptides to plant-based diets can alleviate oxidative stress, while increasing collagen synthesis and accretion in the body. New knowledge of hydroxyproline biochemistry and nutrition aids in improving the growth, health and well-being of humans and other animals.

Effects of compound deer bone extract on osteoporosis model mice and intestinal microflora

The preventive and therapeutic mechanisms of CDBE on osteoporosis were studied by observing the serum bone-related biochemical indicators, bone trabecular micro-structure and intestinal flora in ovariectomized osteoporosis model mice, in order to provide a scientific theoretical basis for the further study on the effect of CDBE on osteoporosis, and the prevention and treatment of osteoporosis with clinical traditional Chinese medicines. The components in CDBE were detected by UHPLC-MS. A mouse osteoporosis model was established by the bilateral ovariectomy in female ICR mice. The biochemical indicators related to osteoporosis were detected, the right proximal tibia was scanned by Micro-CT, the intestinal microflora in the colon contents were examined, and the changes of microflora were taken as the main target to evaluate the effect of CDBE on the intestinal microflora in the model mice. A total of 16 compounds were obtained by the combined application of UHPLC-MS. CDBE could significantly increase the contents of E2, Ca²⁺ , CT, HyP, OCN, FOXP3, P1NP and CTX-II, in the model mice. CDBE could significantly improve the trabecular micro-structure, Tb.N, Tb.Sp, SMI and Conn.D. CDBE could make the intestinal flora of osteoporosis model mice tend to healthy mice in species and quantity. CDBE can improve the symptoms of postmenopausal osteoporosis in mice, with a positive effect on the intestinal flora of postmenopausal mice. Its mechanism of regulating the symptoms of osteoporosis may be related to the regulation of bone-related biochemical indicators in the serum of mice. PRACTICAL APPLICATIONS: This research has a positive impact on the development of functional food with anti-osteoporosis in the future.