Robust and efficient control of therapeutic gene expression is needed for timing and dosing of gene therapy drugs in clinical applications. Ribozyme riboswitch provides a promising building block for ligand-controlled gene-regulatory system, based on its property that exhibits tunable gene regulation, design modularity, and target specificity. Ribozyme riboswitch can be used in various gene delivery vectors. In recent years, there have been breakthroughs in extending ribozyme riboswitch's application from gene-expression control to cellular function and fate control. High throughput screening platforms were established, that allow not only rapid optimization of ribozyme riboswitch in a microbial host, but also straightforward transfer of selected devices exhibiting desired activities to mammalian cell lines in a predictable manner. Mathematical models were employed successfully to explore the performance of ribozyme riboswitch quantitively and its rational design predictably. However, to progress toward gene therapy relevant applications, both precision rational design of regulatory circuits and the biocompatibility of regulatory ligand are still of crucial importance.
Animals ; Cell Line ; Gene Expression ; Gene Expression Regulation ; Genetic Therapy ; Humans ; Ligands ; Models, Theoretical ; RNA, Catalytic ; genetics ; Riboswitch ; genetics

Various artificial riboswitches have been constructed by utilization of designed aptamers or by modification of natural riboswitch systems, because they can regulate gene expression in a highly efficient, precise and fast way, and promise to supply simple cis-acting, modular, and non-immunogenic system for use in future gene therapy applications. In this review, we present an overview of currently available technologies to design and select engineered riboswitches, and discuss some possible technologies that would allow them highly responsive to non-natural ligands, and dynamic control of gene expression in mammalian cells. Though how to bring custom-designed riboswitches as a novel and versatile tool box to gene control system is still a great challenge, the combination of structure-activity relationship information, computer based molecular design, in vitro selection, and high-through screening will serve as powerful tools for further development of riboswitch based gene regulatory systems.
Aptamers, Nucleotide ; genetics ; Gene Expression Regulation ; genetics ; Genetic Engineering ; Genetic Therapy ; Humans ; Protein Biosynthesis ; RNA, Catalytic ; chemistry ; genetics ; Ribosomes ; genetics ; Riboswitch ; genetics

Cyclic diguanylate (c-di-GMP) is a ubiquitous second messenger present in a wide variety of bacteria, which is responsible for cell differentiation, biofilm formation, pathogenic factor generation, and so on. The level of c-di-GMP in bacteria is regulated by two opposing active domains, diguanylate cyclase (DGC) and phosphodiesterase (PDE), which are present in the same bifunctional protein, and in charge of the synthesis and the degradation of c-di-GMP, respectively. The target of c-di-GMP in the bacterial cell consists of PilZ domain and GEMM riboswitch, the only riboswitch that involved in signal transduction. This article gives an overview of c-di-GMP, focusing on its metabolic pathway, regulatory mechanism, biological function of c-di-GMP, and the synthesis of c-di-GMP analogues and their biological activity.
Bacteria ; metabolism ; Cyclic GMP ; analogs & derivatives ; biosynthesis ; metabolism ; Escherichia coli Proteins ; chemistry ; metabolism ; Phosphoric Diester Hydrolases ; chemistry ; metabolism ; Phosphorus-Oxygen Lyases ; chemistry ; metabolism ; Riboswitch ; Second Messenger Systems ; Signal Transduction

Riboswitches are cis-acting domains located in mRNA sequences that could regulate gene expression by sensing small molecules without employing protein. Most known riboswitches in bacteria have naturally evolved to bind essential metabolite ligands and are involved in the regulation of critical genes that are responsible for the biosynthesis or transport of the cognate ligand. The riboswitch-mediated gene expression could be repressed by metabolite analogs, which caused bacterial growth inhibition or even death. A number of leading compounds targeting riboswitches have been discovered. A promising avenue for the development of new class of riboswitch-based antibiotics has been opened. Herein we reviewed the current findings of riboswitches that served as targets for antibacterial drug development and the underlying mechanisms. The development of high-throughput methods and rational drug design for riboswitch-specific drug discovery are relevant challenges are discussed. summarized.
Animals ; Anti-Bacterial Agents ; chemistry ; pharmacology ; Bacteria ; drug effects ; genetics ; Bacterial Proteins ; chemistry ; genetics ; Drug Design ; Drug Discovery ; Flavin Mononucleotide ; chemistry ; genetics ; Gene Expression Regulation, Bacterial ; Guanine ; chemistry ; High-Throughput Screening Assays ; methods ; Ligands ; Lysine ; analogs & derivatives ; chemistry ; genetics ; Riboswitch ; drug effects ; Thiamine Pyrophosphatase ; chemistry ; genetics