Therapeutic actions of tea phenolic compounds against oxidative stress and inflammation as central mediators in the development and progression of health problems: A review focusing on microRNA regulation

Chromatin is not an inert structure, but rather an instructive DNA scaffold that can respond to external cues to regulate the many uses of DNA. A principle component of chromatin that plays a key role in this regulation is the modification of histones. There is an ever-growing list of these modifications and the complexity of their action is only just beginning to be understood. However, it is clear that histone modifications play fundamental roles in most biological processes that are involved in the manipulation and expression of DNA. Here, we describe the known histone modifications, define where they are found genomically and discuss some of their functional consequences, concentrating mostly on transcription where the majority of characterisation has taken place.

A major mechanism in the cellular defense against oxidative or electrophilic stress is activation of the Nrf2-antioxidant response element signaling pathway, which controls the expression of genes whose protein products are involved in the detoxication and elimination of reactive oxidants and electrophilic agents through conjugative reactions and by enhancing cellular antioxidant capacity. At the molecular level, however, the regulatory mechanisms involved in mediating Nrf2 activation are not fully understood. It is well established that Nrf2 activity is controlled, in part, by the cytosolic protein Keap1, but the nature of this pathway and the mechanisms by which Keap1 acts to repress Nrf2 activity remain to be fully characterized and are the topics of discussion in this minireview. In addition, a possible role of the Nrf2-antioxidant response element transcriptional pathway in neuroprotection will also be discussed.

MicroRNAs (miRNAs) are a class of small noncoding RNAs, which function in posttranscriptional regulation of gene expression. They are powerful regulators of various cellular activities including cell growth, differentiation, development, and apoptosis. They have been linked to many diseases, and currently miRNA-mediated clinical trial has shown promising results for treatment of cancer and viral infection. This review provides an overview and update on miRNAs biogenesis, regulation of miRNAs expression, their biological functions, and role of miRNAs in epigenetics and cell-cell communication. In addition, alteration of miRNAs following exercise, their association with diseases, and therapeutic potential will be explained. Finally, miRNA bioinformatics tools and conventional methods for miRNA detection and quantification will be discussed.