Ongoing RNAcore Projects
Telomerase mRNA treatment increases telomere length and reverses most of the stigmata of senescence in vascular cells. We find that iPSC-derived endothelial cells from patients with Hutchison Gilford Progeria Syndrome (HGPS) have shorter telomeres, reduced replicative capacity and function (e.g. ability to generate nitric oxide or form networks in Matrigel), increased release of inflammatory cytokines, aberrant transcriptional profile, abnormal cell and nuclear morphology, and DNA damage. All of these abnormalities are fully or partially reversed by two transfections with mRNA encoding human telomerase. In a murine model of HGPS, overexpression of telomerase using a lentiviral vector also improves vascular function, reduces DNA damage, and mice live longer (see Mojiri A et al, Eur Heart J, 2021)
Transflammation is required for cell fate transitions. Damage- or Pathogen-associated molecular patterns (DAMPs or PAMPs) stimulate pattern recognition receptors such as Toll-like receptor 3 (TLR3) which triggers inflammatory signaling. The inflammatory signaling (mediated by NFkB or other transcriptional activators) causes changes in the expression and/or activity of epigenetic modifiers to increase DNA accessibility. For example, histone acetyltransferase (HAT) expression is increased, thereby augmenting acetylation of histone proteins to increase DNA accessibility. In addition NFkB increases the expression of inducible nitric oxide synthase (iNOS) which translocates to the nucleus and binds to epigenetic modifiers like the NURD complex, nitrosylating them and reducing their activity. The process of transflammation appears to be necessary for any cell fate transition, in this example a fibroblast to induced pluripotent stem cell (iPSC). (See Lee et al, Cell 2012; Cooke JP, Circulation 2013; Sayed et al Circulation 2015; Zhou et al, Cell Reports 2016; Meng et al, Circ Res 2016; Sayed et al, Stem Cell 2017; Li et al, Circulation 2019; Chanda et al Circulation 2019; Meng et al, Circulation 2020)
Transflammation induces a glycolytic shift (increased glycolysis, reduced oxidative phosphorylation) that is associated with mitochondrial export of citrate to the nucleus. There, the citrate is converted to acetylcoA for histone acetylation, to increase DNA accessibility required for cell fate transitions. (See Li et al, Circulation 2019)
Lipid nanoparticles (LNPs) are used to protect and to carry therapeutic nucleic acids (e.g. mRNA, circRNA) to the cell cytoplasm. The LNPs are typically composed of cholesterol, structural lipids, and ionizable or cationic lipids, with polyethylene glycol (PEG) on the surface of the LNP.