Research in the Holford group applies an evolutionarily integrated approach to the discovery and characterization of novel bioactive venom peptides. Research projects in our lab applies inventive tools from chemistry and biology to: (1) discover disulfide-rich peptides from a venom source, (2) develop high-throughput methods for characterizing structure-function peptide interactions, and (3) deliver novel peptides to their site of action for therapeutic application. We use a learn from nature, Mollusks to Medicine, strategy to discover novel peptides from venomous marine snails that could be used to manipulate cellular physiology pertaining to pain and cancer. We have published several papers outlining our peptide drug discovery strategy as it pertains to venomous snail evolution and phylogeny. The correlation between anatomical function and molecular character in venomous marine snails was first identified by in our group and has provided a tool for effectively improving the time and cost required to screen new snail lineages. Our publications also demonstrate the computational methods for optimizing the activity of venom peptide:channel complexes and application of nanocontainers for peptide drug delivery. We also explore chemical pigmentation in nature. The Holford Lab research program is global, interdisciplinary and collaborative with impacts ranging from evolution and molecular systematics to nanotechnology, biomedicine and drug discovery.
Topic 1: Taxonomy, Phylogeny, and Systematics of Venomous Marine Snails
The Tererbridae (auger snails) are a family of globally distributed predatory marine snails that use venom to subdue their prey. The >400 described terebrid species are highly representative of a broad range of feeding strategies, more so than any other venomous marine taxa. We describe the taxonomy, phylogeny, and venom diversity of terebrid snails. Our results produced the first molecular phylogeny of the Terebridae and used it to identify terebrid lineages that used a venom apparatus similar to cone snails to produce bioactive venom peptides (teretoxins). The correlation between phylogeny and anatomical analyses is a road map for studying terebrid snails and their venom peptides. We are using terebrid taxonomy and teretoxins to clarify conoidean venom evolution.
Topic 2: Venomics - Venom Peptide Discovery, Diversification and Evolution
Animal venoms are complex natural secretions made up of a concoction of bioactive compounds. Despite their complexity, there are generally high levels of venom convergence throughout the animal kingdom that includes similarities in gene structure and targets. We investigate questions pertaining to the evolution, production and function of venom peptides in predatory marine snails of the Terebridae. Venom peptides from predatory organisms are a resource for investigating evolutionary processes such as adaptive radiation or diversification, and exemplify promising targets for biomedical drug development. Terebridae are an understudied lineage of conoidean snails, which also includes cone snails and turrids. Characterization of cone snail venom peptides, conotoxins, has revealed a venom arsenal of bioactive peptides used to investigate physiological cellular function, predator-prey interactions, and to develop novel therapeutics. However, venom diversity of other conoidean snails remains poorly understood. My group applies a systems biology approach, venomics, which combines genomics, transcriptomics, and proteomics to discover new bioactive venom peptides and to study venom diversification in terebrids with in an evolutionary phylogenetic context. Using venomics we produced the first the first structural characterization of a terebrid peptide, Tv1, and was the first to identify novel teretoxin venom gene superfamilies.
Topic 3: High Throughput Venom Peptide Characterization
Venom peptides are levers that manipulate cell signaling. We are interested in finding new therapies for pain and cancer by creating high throughput methods for screening novel venom peptides. Each venomous marine snail of the family Conoidea can produce hundreds of novel peptides to in their venom arsenal. From the breakthrough success of the first commercial venom snail drug Ziconotide (Prialt ®) used to treat chronic pain in HIV and cancer patients, we know that these peptides can potentially be used to develop novel therapies for treating human disorders. Collaboratively we are developing peptide microarrays, microfluidic techniques, and in vitro and in vivo cell and animal assays for rapidly screening venom peptides.
Topic 4: Venom peptide optimization and drug delivery
Peptides are promising therapeutic agents, however these natural compounds often need to be optimized to be used successfully as drug compounds. For example, the first snail drug approved for biomedical use, ziconotide (Prialt ®), is used to treat chronic pain in HIV and cancer patients. Despite being a breakthrough drug, ziconotide has a major drawback in that as a peptide drug, its size and complexity prevents its widespread application and a spinal tap is required to deliver it to patients. To address this issue, we are combining chemical and recombinant biology techniques to devise a method for encapsulating venom peptides from marine snails in viral capsids for delivery to their site of action. In collaborative projects we’re also developing new computational methods for optimizing the function of venom peptides to make them more selective for their molecular targets. The large size of venom peptides and the lack of solved structures of venom peptides bound to their peptide channel targets are barriers to computational docking and design of venom peeptides to screen their functional activity. To address these issues, the first tool we’ve developed is ToxDock and it is freely available at http://rosie.rosettacommons.org/tox_dock.