VIMM Affiliate Member
Professor and Chair
Department of Cell Biology, Microbiology and Molecular Biology
University of South Florida

Research Focus/Projects

The Chalfant Laboratory has historically focused on two major, but diverse areas of basic science in regards to Cell signaling, Cell Biology, Microbiology, and Molecular Biology. Specifically, the Chalfant Laboratory studies mechanisms of cell signaling associated with both bioactive lipids and RNA splicing with a focus on both basic science mechanisms as well as in many cases clinical translation. In regards to their bioactive lipid research, these studies have recently exploded into numerous sectors with clinical application. For example, the Chalfant Laboratory initially described the lipid:protein interaction of the sphingolipid, ceramide-1-phosphate (C1P), with the phospholipase, cPLA₂a. This initial basic research finding has now advanced to a possible new therapeutic target to treat sepsis as well as a therapeutic target to drive rapid wound healing for both acute wounds and chronic wounds. Through this research area, the Chalfant Laboratory then began the global lipidomics initiative at VCU to rapidly analyze the downstream bioactive lipids associated with both this lipid:protein interaction and various human disease states. Through this initiative, clinicians were brought together with basic scientists as bioactive lipids are most proximal to clinical phenome, which led recently to numerous new findings in cardiovascular disease and treatments, sepsis, traumatic injury, and peripheral wound healing. They also continue our strong basic research in this area by exploring how bioactive lipids are synthesized and transported, which led to a co-corresponding author manuscript in 2013 published in Nature on the ceramide-1-phosphate transporter (CPTP).

As to RNA splicing research of the Chalfant laboratory, their main focus has been cancer cell signaling specializing in non-small cell lung cancer (NSCLC). Due to the limited number of researchers in this area, this research continues to remain innovative and underexplored. In this regard, the Chalfant Laboratory has identified key RNA splicing events and signaling mechanisms mediating the tumor maintenance of NSCLC cells. For example, the caspase 9 splice variant, caspase 9b, was shown by the Chalfant laboratory to interact with cIAP1 to activate the NF-kB pathway in NSCLC cells. These findings have been further expanded to a number of RNA splicing events via deep RNA sequencing to identify specific RNA splicing signatures for individual NSCLC patients, which are linked to therapeutic sensitivity.

In another exciting project from just a basic science point of view, the mechanistic research from the laboratory is undertaking studies to validate the “unmasking hypothesis”. For years, researchers in the RNA splicing field overlooked the presence of multiple RNA binding domains (RBDs) in RNA trans-factors. Essentially, SELEX was used to identify high affinity binding sites for a specific RNA trans-factor, and then a dogmatic scientific view wasfounded: One RNA trans-factor, one optimal binding preference. They simply asked the question: “Why is the RNA trans-factor, hnRNP L, binding to a non-standard RNA cis-element in NSCLC cells?” The asking of this straightforward question led to the identification of a specific phosphorylation site that “unmasks” C-terminal RBDs in hnRNP L to bind a separate RNA sequence with high affinity. The RNA trans-factor retains its constitutive RNA splicing function, but also has additional regulatory abilities for a separate set of RNA splicing events important in cell survival and tumor maintenance. These findings are expected to drive a complete paradigm shift in cell signaling and RNA splicing. Furthermore from a therapeutic standpoint, the targeting of just the activated forms of RNA trans-factors is now possible. Importantly, the laboratory has also extended their RNA splicing research into different cancers (e.g. breast cancer and anoikis resistance) as well as cardiovascular disease and type 1 diabetes.