Molecular and Cell Biology Research Faculty

Shaun Brinsmade

Email: sb1344@georgetown.edu
website
Shaun is a bacterial physiologist and his laboratory studies the connections between bacterial metabolism and the molecular mechanisms that control toxin production in bacterial pathogens. He is also interested in interspecies cooperation and antagonism during polymicrobial infections such as those of the cystic fibrosis lung and chronic wounds. The current focus of his research is on Staphylococcus aureus and Enterococcus faecalis – opportunistic human pathogens that pose a major health and economic burden globally. Specifically, the lab is investigating how collaborating bacteria help S. aureus construct its membrane during infection. Interestingly, these bacterial collaborations often result in emergent behaviors with respect to persistence, virulence, and antibiotic tolerance, and worsen patient outcomes. 

Elena Casey, see Elena Silva

Thomas Coate

Email: tmc91@georgetown.edu
website
Development of the neurons in the inner ear
The long-term goal of the research in the Coate laboratory will be to define the signaling mechanisms underlying neural development within sensory systems and how synaptic connections can be reestablished in cases of damage or disease. In the field of developmental neuroscience, we are now at an exciting time where we can take multi-faceted approaches to understand (with excellent temporal and spatial resolution) the mechanisms by which precise cell types coordinate appropriate axon guidance decisions and synapse formation. In our research, we aim to understand the mechanisms by which spiral ganglion neurons (SGNs) make functional connections with mechanosensory hair cells in the mouse cochlea. We are currently addressing how secreted Semaphorins, which activate Neuropilin/Plexin co-receptors, control SGN axon guidance decisions in the cochlear sensory epithelium. We are also investigating how the transcription factor Pou3f4 controls the expression of axon guidance factors in the developing cochlea (such as ephrins and Eph receptors) and how those factors control cochlear innervation. The cochlea provides an excellent model for discovering how circuits assemble within a complex organ system, as it is composed of an array of cell types and structures precisely arranged to detect a range of sound frequencies.  

Jeffrey Huang

Email: jh1659@georgetown.edu
website
Neural regeneration and neuron-glia interactions
The goal of my research is to understand how glial cells regulate neuronal function in the mammalian central nervous system (CNS). We focus on oligodendrocytes, a type of glia, whose cellular processes engage with and enwrap CNS axons, and form the lipid-rich myelin membranes required for rapid, saltatory axonal conduction. Oligodendrocyte loss or dysfunction has a profound impact on brain development, homoeostasis and aging, and has been implicated in many neurological disorders including certain leukodystrophies, multiple sclerosis (MS), cerebral palsy, Alzheimer’s disease, schizophrenia, and autism.
  We are currently investigating the mechanisms by which oligodendrocytes interact and communicate with axons, and how their interactions might promote axonal integrity and survival. We are also investigating the mechanism of CNS regeneration, with a focus on how oligodendrocytes regenerate from endogenous neural progenitor cells to replace myelin during homeostatic turnover or after demyelination. We use primary oligodendrocyte/neuron co-cultures, transgenic mice, and models of experimental CNS injury and demyelination, combined with molecular biology and imaging tools to address these questions.

Ronda Rolfes

Email: rolfesr@georgetown.edu
website
Transcriptional control in the yeasts Saccharomyces and Candida
Research in my laboratory is focused on elucidating the mechanisms that yeast cells use to sense external conditions – such as nutrient abundance and host status – and how these cells alter gene expression in response to these conditions. We are studying expression of the enzymes that comprise the purine nucleotide biosynthetic pathway in Saccharomyces cerevisiae. In Candida albicans, we are investigating how filamentation is controlled at the genetic level.

Anne Rosenwald

Email: rosenwaa@georgetown.edu

Protein trafficking and ion homeostasis
 The Rosenwald laboratory investigates a number of different aspects of life at the microbial level, including membrane traffic, cell wall biosynthesis, and ion homeostasis in Saccharomyces cerevisiae (Baker’s yeast) and its close but pathogenic relative, Candida glabrata. We use approaches that combine classical techniques of biochemistry, cell biology, and genetics, but more recently have also included bioinformatics and genomics in our arsenal of tools. 

Elena Silva

Email: emc26@georgetown.edu
website
Neural induction in Xenopus laevis
The goal of the Silva lab is to understand the transcriptional regulation of a class of genes involved in the formation of the early vertebrate body plan. Patterning events such as the establishment of neural tissues require a series of signal transduction events that lead to the transcription of a set of genes. Few of the details of transcriptional regulation in vertebrate development have been deciphered. However, the ability to generate transgenic frogs has revolutionized the field, allowing rapid analysis of promoter functions in a large number of embryos. This technique, along with embryology, traditional biochemical and molecular assays, and expression screens now enables us to define the factors required for the regulation of genes involved in early vertebrate development.

Steven Singer

Email: sms3@georgetown.edu
website
Mucosal immunity and giardiasis
My research centers on the protozoan parasite, Giardia lamblia. Giardia replicates in the small intestines of many species of mammals and is a major cause of human diarrheal disease throughout the world. In the U.S., Giardia infections are mainly found in campers and hikers who forget to treat their water, as well as in daycare and nursing home situations. Although Giardia is a significant cause of diarrhea, the majority of infections are actually subclinical. Indeed, recent data suggest that Giardia infection may actually reduce the severity of diarrhea due to other pathogens. We are studying immune responses against this parasite in humans and mice in order to understand how these responses contribute to the variety of clinical outcomes observed. For example, do immune responses against Giardia reduce the severity of infections by other pathogens? And how do these immune responses contribute to intestinal cramps and nutrient malabsorption that are the hallmarks of giardiasis?

Tiffany Zarrella

Email: tiffany.zarrella@georgetown.edu
 Interactions between co-infecting bacterial pathogens
       Bacteria often exist in multispecies communities, where polymicrobial interactions influence antibiotic resistance, motility, lifestyle, and other bacterial behaviors which collectively affect pathogenesis. Despite this, many species are studied in isolation and therefore many of the molecules underlying interspecies interactions as well as the unique behaviors that emerge in native environments have not been deciphered. Pseudomonas aeruginosa and Staphylococcus aureus are co-infecting pathogens that frequently cause chronic, antibiotic resistant infections in the respiratory tracts of people with cystic fibrosis. We are interested in defining novel molecules that play important roles in modifying bacterial behaviors and determining how bacteria respond to interactions within these communities. This research will ultimately enhance our understanding of bacterial communication and reveal new targets to disrupt persistent bacterial infections.