Normal and cancer cells express more diversity in proteins than can be accounted for by the predicted number of expressed genomic DNA sequence. Expansion of the genomically encoded expressed sequences through alternative processing of RNA, such as mRNA editing, is a logical hypothesis for how protein diversity and variations seen as tissue-specific and regulated expression of proteins can be achieved. The specific focus of the research is to identify and characterize novel mammalian mRNA editing systems that employ a zinc-dependent deamination mechanism for the post-transcriptional conversion of cytidine to uridine at select sites within mRNAs. Computational modeling has suggested a family of mammalian enzymes known as Cytidine Deaminases Active on RNA or CDARs as responsible for C to U editing of mRNAs.
The expression of these enzymes in biology suggests that mRNA editing may be involved in numerous physiological processes and could be manipulated for the prevention of cardiovascular disease, HIV infection and cancer, and is also necessary for production of antibodies in B lymphocytes. Recent evidence indicates that the enzyme involved in suppressing HIV-1 infectivity (CEM15) and the enzyme that promotes antibody production (AID) may act to mutate deoxy cytidine in DNA rather than or in addition to RNA.
Our research involves molecular biology and protein techniques, DNA microarray analyses and computational biology to identify the mRNAs that are edited by CDARs and to determine the biological consequence of these editing events in terms of the predicted changes in the types of protein structures and functions that can be expressed. Our studies have demonstrated how cytidine to uridine mRNA editing contributes to expansion in the diversity of expressed mRNA sequences known collectively as the transcriptome.
We are also evaluating the regulatory mechanisms controlling the expression of editing factors and their localization in the cell nucleus. The development of this new information will establish an important new annotation of the human genome that will serve as a frame of reference for studies of proteins involved in health and disease and mechanisms regulating their expression.
Suppression of HIV-1 and Viral Infectivity Through Small Molecule Vif Antagonists (SMVA)|
United States Serial NO.: 10/934,090
Filed Date: September 3, 2004
Title: Cytidine Deaminase Activators, Deoxycytidine Deaminase Activators, VIF Antagonists, and Methods of Screening for Molecules Thereof
Invented by: Harold Smith, Mark Sowden, Joseph Wedekind, Stephen Dewhurst, Baek Kim
Arrayed pnc-Si Membranes as Screens for Drugs That Disrupt Protein-Protein Interactions|
United States Serial NO.: 12/878,700
Filed Date: September 9, 2010
Title: Drug Screening Via Nanopore Silicon Filters
Invented by: Harold Smith, James McGrath, Joseph Wedekind
2014 Mar 24
Prohaska KM, Bennett RP, Salter JD, Smith HC. "The multifaceted roles of RNA binding in APOBEC cytidine deaminase functions." Wiley interdisciplinary reviews. RNA.. 2014 Mar 24; Epub 2014 Mar 24.
2014 Feb 13
Ofori LO, Hilimire TA, Bennett RP, Brown NW, Smith HC, Miller BL. "High-affinity recognition of HIV-1 frameshift-stimulating RNA alters frameshifting in vitro and interferes with HIV-1 infectivity." Journal of medicinal chemistry.. 2014 Feb 13; 57(3):723-32. Epub 2014 Jan 15.
Smith HC, Bennett RP, Kizilyer A, McDougall WM, Prohaska KM. "Functions and regulation of the APOBEC family of proteins." Seminars in cell & developmental biology. 2012 May; 23(3):258-68. Epub 2011 Oct 06.
2011 Sep 9
McDougall WM, Smith HC. "Direct evidence that RNA inhibits APOBEC3G ssDNA cytidine deaminase activity." Biochemical and biophysical research communications.. 2011 Sep 9; 412(4):612-7. Epub 2011 Aug 11.
2011 Sep 2
McDougall WM, Okany C, Smith HC. "Deaminase activity on single-stranded DNA (ssDNA) occurs in vitro when APOBEC3G cytidine deaminase forms homotetramers and higher-order complexes." The Journal of biological chemistry.. 2011 Sep 2; 286(35):30655-61. Epub 2011 Jul 07.