Search

Natural products with health benefits, nutraceuticals, have shown considerable promise in many studies; however, this potential has yet to translate into widespread clinical use for any condition. Notably, many drugs currently on the market, including the first analgesic aspirin, are derived from plant extracts, emphasizing the historical significance of natural products in drug development. Curcumin and resveratrol, well-studied nutraceuticals, have excellent safety profiles with relatively mild side effects. Their long history of safe use and the natural origins of numerous drugs contrast with the unfavorable reputation associated with nutraceuticals. This review aims to explore the nutraceutical potential for treating pseudoachondroplasia, a rare dwarfing condition, by relating the mechanisms of action of curcumin and resveratrol to molecular pathology. Specifically, we will examine the curcumin and resveratrol mechanisms of action related to endoplasmic reticulum stress, inflammation, oxidative stress, cartilage health, and pain. Additionally, the barriers to the effective use of nutraceuticals will be discussed. These challenges include poor bioavailability, variations in content and purity that lead to inconsistent results in clinical trials, as well as prevailing perceptions among both the public and medical professionals. Addressing these hurdles is crucial to realizing the full therapeutic potential of nutraceuticals in the context of pseudoachondroplasia and other health conditions that might benefit. [ABSTRACT FROM AUTHOR]

Pseudoachondroplasia (PSACH), a severe dwarfing condition associated with early-onset joint degeneration and lifelong joint pain, is caused by mutations in cartilage oligomeric matrix protein (COMP). The mechanisms underlying the mutant-COMP pathology have been defined using the MT-COMP mouse model of PSACH that has the common D469del mutation. Mutant-COMP protein does not fold properly, and it is retained in the rough endoplasmic reticulum (rER) of chondrocytes rather than being exported to the extracellular matrix (ECM), driving ER stress that stimulates oxidative stress and inflammation, driving a self-perpetuating cycle. CHOP (ER stress signaling protein) and TNFα inflammation drive high levels of mTORC1 signaling, shutting down autophagy and blocking ER clearance, resulting in premature loss of chondrocytes that negatively impacts linear growth and causes early joint degeneration in MT-COMP mice and PSACH. Previously, we have shown that resveratrol treatment from birth to 20 weeks prevents joint degeneration and decreases the pathological processes in articular chondrocytes. Resveratrol's therapeutic mechanism of action in the mutant-COMP pathology was shown to act by primarily stimulating autophagy and reducing inflammation. Importantly, we demonstrated that MT-COMP mice experience pain consistent with PSACH joint pain. Here, we show, in the MT-COMP mouse, that resveratrol treatment must begin within 4 weeks to preserve joint health and reduce pain. Resveratrol treatment started at 6 or 8 weeks (to 20 weeks) was not effective in preventing joint degeneration. Collectively, our findings in MT-COMP mice show that there is a postnatal resveratrol treatment window wherein the inevitable mutant-COMP joint degeneration and pain can be prevented. [ABSTRACT FROM AUTHOR]

Research demonstrates that the DNA cleavage activity of the yeast homing endonuclease can be turned on and off with a redox switch. Data show that Cys-67/Cys-365 variants of the endonuclease exhibit different DNA binding conformations under redox conditions.The DNA binding defects reduce DNA cleavage activities of the disulfide containing proteins.

Misfolding mutations in cartilage oligomeric matrix protein (COMP) cause it to be retained within the endoplasmic reticulum (ER) of chondrocytes, stimulating a multitude of damaging cellular responses including ER stress, inflammation, and oxidative stress, which ultimately culminates in the death of growth plate chondrocytes and pseudoachondroplasia (PSACH). Previously, we demonstrated that an antioxidant, resveratrol, substantially reduces the intracellular accumulation of mutant‐COMP, dampens cellular stress, and lowers the level of growth plate chondrocyte death. In addition, we showed that resveratrol reduces mammalian target of rapamycin complex 1 (mTORC1) signaling, suggesting a potential mechanism. In this work, we investigate the role of autophagy in treatment of COMPopathies. In cultured chondrocytes expressing wild‐type COMP or mutant‐COMP, resveratrol significantly increased the number of Microtubule‐associated protein 1A/1B‐light chain 3 (LC3) vesicles, directly demonstrating that resveratrol‐stimulated autophagy is an important component of the resveratrol‐driven mechanism responsible for the degradation of mutant‐COMP. Moreover, pharmacological inhibitors of autophagy suppressed degradation of mutant‐COMP in our established mouse model of PSACH. In contrast, blockage of the proteasome did not substantially alter resveratrol clearance of mutant‐COMP from growth plate chondrocytes. Mechanistically, resveratrol increased SIRT1 and PP2A expression and reduced MID1 expression and activation of phosphorylated protein kinase B (pAKT) and mTORC1 signaling in growth plate chondrocytes, allowing clearance of mutant‐COMP by autophagy. Importantly, we show that optimal reduction in growth plate pathology, including decreased mutant‐COMP retention, decreased mTORC1 signaling, and restoration of chondrocyte proliferation was attained when treatment was initiated between birth to 1 week of age in MT‐COMP mice, translating to birth to approximately 2 years of age in children with PSACH. These results clearly demonstrate that resveratrol stimulates clearance of mutant‐COMP by an autophagy‐centric mechanism. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research. [ABSTRACT FROM AUTHOR]

Examines the insertion of a reversible reduction oxidation switch into a rare-cutting DNA endonuclease. Modulation in the activity of proteins; Accounts of DNA binding for the decreased DNA cleavage activities of the proteins; Control of homing endonuclease activity using a molecular switch.

The PI-SceI protein from Saccharomyces cerevisiae is a member of the LAGLIDADG family of homing endonucleases that have been used in genomic engineering. To assess the flexibility of the PI-SceI-binding interaction and to make progress towards the directed evolution of homing endonucleases that cleave specified DNA targets, we applied a two-hybrid method to select PI-SceI variants from a randomized expression library that bind to different DNA substrates. In particular, the codon for Arg94, which is located in the protein splicing domain and makes essential contacts to two adjacent base-pairs, and the codons for four proximal residues were randomized. There is little conservation of the wild-type amino acid residues at the five randomized positions in the variants that were selected to bind to the wild-type site, yet one of the purified derivatives displays DNA-binding specificity and DNA endonuclease activity that is similar to that of the wild-type enzyme. A spectrum of DNA-binding behaviors ranging from partial relaxation of specificity to marked shifts in target site recognition are present in variants selected to bind to sites containing mutations at the two base-pairs. Our results illustrate the inherent plasticity of the PI-SceI/DNA interface and demonstrate that selection based on DNA binding is an effective means of altering the DNA cleavage specificity of homing endonucleases. Furthermore, it is apparent that homing endonuclease target specificity derives, in part, from constraints on the flexibility of DNA contacts imposed by hydrogen bonds to proximal residues. [Copyright &y& Elsevier]