Researchers@EVMS

My laboratory research focus derives from a broad background in DNA replication and from our research regarding Pur family protein, Pur-alpha, and its coding gene, PURA. In 2018, I co-authored an invited Gene review of PURA structure and evolutionary conservation that included a review of the characterization of Pur-alpha protein. In 2017, as part of the Gene Wiki initiative, I developed the PURA gene Wikipedia site. I have begun to extend our studies of the Pur family, through work with a Pur based peptide as a therapeutic for guanine (G)-rich repeat expansion diseases and for certain cancers with amplified oncogenes containing G-rich promoter regions. We have developed a peptide, TZIP, comprising a Pur polynucleotide binding domain based on the retention of conserved sequences in this binding domain among species during evolution. In 2020, our paper in BBC-Molecular Cell Research concerned the ability of this peptide to help form and un-form G-quadruplex secondary structure in a hexanucleotide repeat expansion (HRE) of the C9orf72 (C9) gene. This repeat expansion is the most common genetic cause of both amyotrophic lateral sclerosis and frontotemporal dementia, and is a canonical Pur-alpha ‘binding element’. In animal models, Pur-alpha reduces neurodegeneration caused by expansions of these G-rich elements. G-quadruplex structures have a proposed regulatory function in RNA metabolism, and Pur-alpha has a known role in RNA transport. We are investigating the role of G-quadruplex interaction with Pur-alpha in RNA transport in repeat expansion diseases. The Pur-based peptide may help facilitate RNA transport in cells where Pur-alpha is preferentially bound to the G-rich HRE. This peptide is also beneficial in certain types of cancer that have amplified oncogenes with G-quadruplex-forming sequences in their promoter regions. Our work indicates that TZIP peptide treatment of these cancer cells in culture reduces their proliferation and increases cancer cell death. The peptide has a transporter sequence that allows it to pass into cells, where fluorescently tagged peptide can be visualized in the cytoplasm as well as the nucleus. Importantly, intracerebroventricular injection of the peptide into mice does not cause acute toxicity at concentrations used in our studies.

A second focus of the lab is to understand the function of Pur family member, Pur-gamma. Our data indicate a coordinate function for Pur-gamma with WRN protein in cells undergoing developmental reorganization, high replicative potential or viral infection– all of which lead to genomic stress. The cellular functions attributed to WRN support the maintenance of genome stability. There are two isoforms of Pur-gamma, Purg-A and Purg-B, and we are currently developing monoclonal antibodies to distinguish these. Our research group is interested in determining the mechanistic pathways in brain cells in which the two isoforms of Pur-gamma differentially interact with WRN and with family member, Pur-alpha, known to be essential for brain development.

Research funding derived from:

• National Institutes of Health
• Alzheimer's and Related Diseases Research Award Fund
• EVMS Grant Enhancement Fund
• EVMS Professional Enrichment & Growth Award