Developing MRI Contrast
The objectives of this project are to use protein engineering/design to develop MRI contrast reagents with significantly improved contrast capability and targeted imaging capability for the diagnosis and treatment of cancers and other diseases.
Developing Calcium and Proteinase Sensors
The goal of this project is to develop fluorescent sensors for monitoring calcium signaling and proteinase activity in subcellular compartments both in vivo and in vitro. More importantly, a novel class of calcium sensors without using natural trigger calcium binding proteins and FRET pairs has been created for cell imaging high calcium concentrations. In addition, we have created sensors for several classes of proteinases, such as trypsin, chymotrypsin, thrombin and caspases, for real-time imaging of enzymatic activity in live cells and disease tissues.
These developed probes will have wide applicability in studies of human diseases including various cardiomyopathies, Alzheimer's Disease, cancer, and lens cataract formation that are known to be associated with altered Ca(II) signaling and protease activation/inhibition.
G Protein Coupled Receptors
Ca(II) -sensing receptor (CaSR) represent a class of receptors that respond to changes in the extracellular Ca(II) concentration [Ca(II) ] o and activate multiple signaling pathways. Nearly one hundred mutations and polymorphisms have been identified in the CaSR that result in reduced or enhanced sensitivity to [Ca(II) ] o as observed in familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NSHPT), on the one hand, and autosomal dominant hypoparathyroidism (ADH), on the other.We are investigating the mechanism of extracellular calcium signaling by calcium sensing receptors in collaboration with Dr. Ed Brown at the Brigham and women's hospital
Integrating Intracellular and Extracellular Calcium Signaling
Calmodulin has been found to interact with more than 300 proteins including phophodiesterase, myosin light chain kinase, CaM kinase, calcineurin, nitric oxide synthase, and p68 RNA helicase. In the past few years, it has been reported to associate with channels, pumps, and gap junction. CaM is believed to be instrumental in proper brain function via interacting with diverse calcium-dependent calmodulin binding proteins. We are currently investigating the Calmodulin-mediated regulation of gap junctions in lens cells (in collaboration with Dr. Charles Louis' group, UC riverside), and of the cardiac ryanodine receptor Ca(II) release channel (in collaboration with Dr. Edward Balog, Georgia Tech).
Calciomics is a specialized area of biochemistry focusing on the study of calcium-binding biological macromolecules and proteins to understand the factors that contribute to calcium-binding affinity and the selectivity of proteins and calcium-dependent conformational change. The objective of this research is to develop bioinformatics methods to predict and identify different classes of calcium binding sites in proteins.
In collaboration with Dr. GT Chen in the Georgia State University Department of Mathematics and Statistics, algorithms for predicting calcium binding sites based on structural and genomic information have been established using geometric, graphing, and statistical algorithms along with a web sever containing up-to-date sequence, structure and literature information about calcium and its binding proteins in chemical, biological, and biomineralization. The Calcium Bank also provides putative calcium binding sites predicted in different genomes.