Matrix metalloproteinases (MMPs) are suggested to play a critical role in extracellular matrix degradation and remodeling during inflammation and wound healing processes. However, the role of MMPs in indomethacin-induced gastric ulcer and its healing process are not clearly understood. This study is aimed at determining the regulation of MMP-9 and -2 activities in indomethacin-induced acute gastric ulceration and healing. Indomethacin-ulcerated stomach extracts exhibit significant up-regulation of pro-MMP-9 (92 kDa) activity and moderate reduction of MMP-2 activity, which strongly correlate with indomethacin dose and severity of ulcer. The anti-inflammatory and antioxidant properties of curcumin, an active component of turmeric, suggest that curcumin may exert antiulcer activity through scavenging reactive oxygen species, by regulating MMP activity, or both. To test these possibilities, the effect of curcumin in indomethacin-induced gastric ulcer is examined by biochemical and histological methods. The results show that curcumin exhibits potent antiulcer activity in acute ulcer in rat model by preventing glutathione depletion, lipid peroxidation, and protein oxidation. Denudation of epithelial cells during damage of gastric lumen is reversed by curcumin through re-epithelialization. Furthermore, both oral and intraperitoneal administration of curcumin blocks gastric ulceration in a dose-dependent manner. It accelerates the healing process and protects gastric ulcer through attenuation of MMP-9 activity and amelioration of MMP-2 activity. Omeprazole, an established antiulcer drug does not inhibit MMP-9 while protecting indomethacin-induced gastric ulcer. We conclude that antiulcer activity of curcumin is primarily attributed to MMP-9 inhibition, one of the major path-ways of ulcer healing.

Endometriosis is characterized by the ectopic development of the endometrium which relies on angiogenesis. Although studies have identified the involvement of different matrix metalloproteinases (MMPs) in endometriosis, no study has yet investigated the role of MMP-2 in endometriosis-associated angiogenesis. The present study aims to understand the regulation of MMP-2 activity in endothelial cells and on angiogenesis during progression of ovarian endometriosis. Histological and biochemical data showed increased expressions of vascular endothelial growth factor (VEGF), VEGF receptor-2, cycloxygenase (COX)-2, von Willebrand factor along with angiogenesis during endometriosis progression. Women with endometriosis showed decreased MMP-2 activity in eutopic endometrium as compared to women without endometriosis. However, ectopic ovarian endometrioma showed significantly elevated MMP-2 activity with disease severity. In addition, increased MT1MMP and decreased tissue inhibitors of metalloproteinases (TIMP)-2 expressions were found in the late stages of endometriosis indicating more MMP-2 activation with disease progression. In vitro study using human endothelial cells showed that prostaglandin E2 (PGE2) significantly increased MMP-2 activity as well as tube formation. Inhibition of COX-2 and/or phosphorylated AKT suppressed MMP-2 activity and endothelial tube formation suggesting involvement of PGE2 in regulation of MMP-2 activity during angiogenesis. Moreover, specific inhibition of MMP-2 by chemical inhibitor significantly reduced cellular migration, invasion and tube formation. In ovo assay showed decreased angiogenic branching upon MMP-2 inhibition. Furthermore, a significant reduction of lesion numbers was observed upon inhibition of MMP-2 and COX-2 in mouse model of endometriosis. In conclusion, our study establishes the involvement of MMP-2 activity via COX-2-PGE2-pAKT axis in promoting angiogenesis during endometriosis progression.

Abstract:  Matrix metalloproteinases (MMPs) are part of a superfamily of metal‐requiring proteases that play important roles in tissue remodeling by breaking down proteins in the extracellular matrix that provides structural support for cells. The intricate balance in protease/anti‐protease stoichiometry is a contributing factor in a number of diseases. Melatonin possesses multifunctional bioactivities including antioxidative, anti‐inflammatory, endocrinologic and behavioral effects. As melatonin affects the redox status of tissues, the association of reactive oxygen species (ROS) with tissue injury under different circumstances may be mitigated by melatonin. Redox signaling is expanding into all areas of basic and clinical sciences, and this timely review focuses on the topic of regulation of MMP activities by melatonin. This is a rapidly growing field. Accumulating evidence indicates that oxidative stress plays an important role in regulating the activities of MMPs that are involved in various cellular processes such as cellular proliferation, angiogenesis, apoptosis, invasion and metastasis. This review offers sections on MMPs, melatonin, major physiological and pathophysiological conditions in the context to MMPs, followed by redox signaling mechanisms that are known to influence the cellular processes. Finally, we discuss the emerging molecular mechanisms relevant to regulatory actions of melatonin on the activities of MMPs. The possibility that melatonin might have therapeutic significance via regulation of MMPs may be a novel approach in the treatment of some diseases.

The discovery of Clustered Regularly Interspaced Palindromic Repeats (CRISPR) and its associated Cas endonucleases in bacterial and archaeal species allowed scientists to modify, utilized, and revolutionize this tool for genetic alterations in any species. Especially the type II CRISPR-Cas9 system has been extensively studied and utilized for precise and efficient DNA manipulation in plant and mammalian systems over the past few decades. Further, the discovery of the type V CRISPR-Cas12 (Cpf1) system provides more flexibility and precision in DNA manipulation in prokaryotes, plants, and animals. However, much effort has been made to employ and utilize the above CRISPR tools for RNA manipulation but the ability of Cas9 and Cas12 to cut DNA involves the nuisance of off-target effects on genes and thus may not be employed in all RNA-targeting applications. Therefore, the search for new and diverse Cas effectors which can precisely detect and manipulate the targeted RNA begins and this led to the discovery of a novel RNA targeting class 2, type VI CRISPR-Cas13 system. The CRISPR-Cas13 system consists of single RNA-guided Cas13 effector nucleases that solely target single-stranded RNA (ssRNA) in a programmable way without altering the DNA. The Cas13 effectors family comprises four subtypes (a-d) and each subtype has distinctive primary sequence divergence except the two consensuses Higher eukaryotes and prokaryotes nucleotide-binding domain (HEPN) that includes RNase motifs i.e. R-X4-6-H. These two HEPN domains are solely responsible for executing targetable RNA cleavage activity with high efficiency. Further, recent studies have shown that Cas13d exhibits higher efficiency and specificity in cleaving targeted RNA in the mammalian system compared to other Cas13 endonucleases of the Cas13 enzyme family. In addition to that, Cas13d has shown additional advantages over other Cas13 variants, structurally as well as functionally which makes it a prominent and superlative tool for RNA engineering and editing. Therefore considering the advantages of Cas13d over previously characterized Cas13 subtypes, in this review, we encompass the structural and mechanistic properties of type VI CRISPR-Cas13d systems, an overview of the current reported various applications of Cas13d, and the prospects to improve Cas13d based tools for diagnostic and therapeutic purposes.