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Spray Drying of Biotherapeutic Compounds
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Since RNA interference (RNAi) was discovered by Fire et al.90 almost two decades ago, it has attracted the attention of scientists to exploit this gene silencing mechanism for the treatment of diseases. Short interfering RNAs (siRNAs) are noncoding small RNAs that mediate RNAi. siRNAs are hydrophilic and negatively charged macromolecules that are incapable of permeating biological membranes. Therapy based on siRNA is an attractive approach for treating conditions characterized by overexpression of genes, including indications that are considered difficult to treat with conventional small molecule drugs.91 As demonstrated by DeVincenzo and others92,93 in Phase II clinical trials, the siRNA therapeutic (ALN-RSV01) targeting the nucleocapsid protein of respiratory syncytial virus (RSV) was shown to possess significant antiviral activity against human RSV infection even in the absence of a delivery vector.
Epigenetic control of cell fate and behavior
Published in David M. Gardiner, Regenerative Engineering and Developmental Biology, 2017
Recently, small RNAs have been described to play large roles in mediating states of cellular differentiation through modulating gene expression states, generally through silencing mechanisms. Small double-stranded RNA molecules, called pre-microRNAs (pre-miRNA), are produced from target genes and processed by the RNA-induced silencing complex (RISC) containing the Dicer protein (Krol et al. 2004). Dicer cleaves the double-stranded structure into two single strands, one of which is the complement of the target gene transcript. The single-stranded mature miRNA then associates with a member of the Argonaute family of proteins, which facilitates base pairing between the miRNA and the target messenger RNA (mRNA). The formation of the new double-stranded structure results in the degradation of the target mRNA, which can no longer be translated to produce a functional protein (Valencia-Sanzhez et al. 2006). The complement of miRNAs within a cell differs based on cell identity and appears to be important in directing the proper development of tissues within an organism (Sayed and Abdellatif 2011). Taken together, the myriad of epigenetic control mechanisms can largely influence states of cellular differentiation, a process that we must hope to control within the context of directed regeneration of complex structures.
Genes and Genomics
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
tRNA is a small RNA molecule (usually about 74–95 nucleotides) that transfers a specific active amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. It has a 3′ terminal site for amino acid attachment. This covalent linkage is catalyzed by an aminoacyl tRNA synthetase. It also contains a three-base region called the anticodon that can base pair to the corresponding three-base codon regions on mRNA. Each type of tRNA molecule can be attached to only one type of amino acid, but because the genetic code contains multiple codons that specify the same amino acid, tRNA molecules bearing different anticodons may also carry the same amino acid (Figure 2.8).
Apoptotic and antiproliferative effects of Inula viscosa L. water extract in the expression of microRnas on HCT 116 cell line: an in vitro study
Published in International Journal of Environmental Health Research, 2023
Betul Apaydın Yildirim, Semin Gedikli, Saban Kordali, Selcuk Kucukaydin
Small RNA molecules called microRNAs (miRNAs), which are 18 to 24 nucleotides in length and have a regulatory role in both healthy and pathological circumstances, are encoded by highly conserved DNA sequences but do not convert into proteins (Saydam et al. 2011). miRNAs are considered to control transcriptional and post-transcriptional levels of cellular gene expression (Jackson and Standart 2007). They play a role in a variety of physiological processes, particularly cell differentiation and cell type determination (Celik et al. 2013).