Trainee Profiles

Naazneen Pic cropped

Project Title

Role of Sialic acids in human evolution and host-pathogen interaction

Project Description

The complex relationship between host and pathogen reflects the struggle of the pathogen to proliferate inside the host and spread to new hosts and the need of the infected individual to control and eradicate the disease. To this respect, my project is focused on the large scale phylogenomic analysis of sialic acid related genes in different organisms in order to understand the biology and evolutionary mechanisms of these genes. In addition, my project also focussed on to understand the interaction of different bacterial toxins (such as Yersinia pestis and Yersinia enterocolitica) with sialic acids.

Techniques

Cell culture, protein purification, ELISA, SDS-PAGE, Western blot, phylogenetic analyses.

Katy

Project Title

The role of Tamm-Horsfall glycoprotein during urinary tract infection

Project Description

One out of every three women in the US is diagnosed with a urinary tract infection (UTI) by the age of 24, with a lifetime risk greater than 50%. Treatment of female UTIs a medical economic burden, accounting for more than $2.4 billion in healthcare costs annually, thus, a better grasp of endogenous immune defenses within the urinary tract will reveal new pathways for preventative interventions. Over 60 years ago, Tamm-Horsfall glycoprotein (THP) was identified as the most abundant urine protein. Subsequent in vitro studies revealed THP interacts with immune cells and cytokines. I hypothesize that THP is a critical host defense component against UTI through modulation of innate immune responses. Preliminary data with THP null mice revealed increased E. coli burden in the bladder and kidneys and higher renal cytokines in null mice 10 days post-infection. Since neutrophils are the first responders to UTI, I am characterizing the impact of THP on neutrophil function. I have observed THP exposure reduces neutrophil ROS production, chemotaxis, and killing of E. coli. Because THP is heavily glycosylated with 30% of its molecular weight composed of sugars, I examined if THP interacts with sialic acid-binding Ig-like lectins (Siglecs). Siglecs are inhibitory immune cell surface receptors present which prevent cell activation in response to self (sialic acid-coated host cells). Excitingly, I have discovered that purified human THP engages Siglec-9 in a sialic acid-dependent manner. Future experiments seek to confirm and characterize Siglec-9-THP signaling in vivo, which may identify THP as a potential pathway to be targeted by future therapeutics.

Techniques

in vivo mouse studies, tissue culture, neutrophil functional assays, bacterial genetics and pathogenesis, protein purification and analyses, ELISA, flow cytometry, Western blotting, PCR.

Emi Sato2

Project Title

Calcium ion effects on keratinocyte proteoglycans and glycosaminoglycans

Project Description

Calcium signaling, hyaluronan and heparan sulfate proteoglycans are known to modulate epidermal cell proliferation and differentiation, but the relationship between these important cellular events is unknown. Our previous work has discovered that a novel member of the parathyroid hormone family (TIP39), and its receptor (PTH2R) regulates intracellular calcium signaling in keratinocytes and influences cell differentiation. Our project focuses on evaluating the link between the function of this hormone on calcium signaling and the control of PGs and GAG expression.

Techniques

Imaging, in vivo studies in mice, cell culture, RNA and protein analysis.

HuangMia2

Project Title

Development of synthetic glycomaterials to intercept cellular development

Project Description

Cellular development is orchestrated by a wide variety of glycans at the cell surface. For example, proteoglycans at the surfaces of embryonic stem cells can facilitate growth factor binding and signaling to allow differentiation to occur. My project aims to employ chemical strategies to generate synthetic materials that recapitulate the functions of proteoglycans in order to exert control over stem cell differentiation.

Techniques

Chemical synthesis, Western blot, ELISA, microscopy, cell culture, PCR, flow cytometry.

Tatsuya

Project Title

Role of Hyaloronan in immune system of Fat

Project Description

Skin immune defense and repair is a coordinated response to a variety of danger signals and involves the complex interactions of several different cell types. Dermal fat participates in antimicrobial defense and inflammation. We have previously shown that high-molecular-weight hyaluronan activates endothelial cells, macrophages and DCs. My research is focus on Adipocyte and how does Hyaluronan plays a role in immune system of Fat tissue.

Techniques

In vivo mice experiment, bacterial infection, wound healing and colitis model. qRT-PCR, Western Blotting, Immunofluorescence, HA purifying,

Alison

Project Title

Defining the role of Siglec signaling during the innate immune response to fungal infection

Project Description

An estimated 1.5 to 2 million people die from fungal infections each year. Candida albicans is the leading cause of fungal mucosal infection in HIV/AIDs patients, the fourth most common cause of hospital acquired bloodstream infections and the source of over 13 million vaginal infections in the United States each year. The fungus exists as a commensal on most healthy adults and infections are thought to be driven by changes in the host response as well as the ability of Candida to quickly adapt to environmental shifts. Recent studies suggest C. albicans interacts with Siglecs but the C. albicans molecules that interact with Siglecs and the contribution of these interactions to disease pathogenesis remain unknown. The goal of this project is to identify and characterize Siglec-fungal interactions that may modulate the innate immune response to fungal pathogens, including C. albicans, and influence colonization and pathogenesis. Identifying mechanisms by which fungal pathogens modulate the host immune response not only provides potential targets in the development of antimicrobial drugs but can inform the design of new treatment strategies that amplify protective host responses during infection.

Techniques

in vivo studies in mice, molecular biology, isolation of primary innate immune cells, neutrophil and macrophage killing and activation assays, fungal genetics and pathogenesis, cell culture, flow cytometry, Western blotting, immunoprecipitation, qRT-PCR

Picture of Anne Phan

Project Title

Heparan sulfates in Wound Repair and Regeneration.

Project Description

Although heparan sulfate is a major bioactive component of the extracellular matrix that can regulate signaling of numerous growth factors previously implicated in wound repair (TGF-β, FGF, VEGF, HGF and KGF), the role of heparan sulfate in wound repair is not well understood. Remarkably, 3-O-sulfation in rat skin is higher (~10%) than in any other organ (typically ≤1%). The level of 3-O-sulfation in the skin of other mammals and its biological function have not been analyzed. The goal of this project is to characterize the structure and function of heparan sulfate during wound repair and regeneration. Techniques: Microsurgery (amputation, nerve deviation, skin/bead grafts, heterotopic heart transplant), whole mount skeletal preparations, histology, whole mount immunostaining, limb development, amphibian biology, regeneration

Picture of Dr. Chrissa Dwyer for UCSD Programs of Excellence in Glycosciences

Project Description

My research is focused on the role of glycosaminoglycans, heparan sulfate and chondroitin sulfate, in childhood neurological disorders Sanfilippo Syndrome (MPSIIIA) and Rett Syndrome. The goal of my project is to determine how the expression of glycosaminoglycans by different cell types in the brain, including vascular endothelial cells, contributes to disease pathogenesis. Previous studies have shown heparan sulfate present on the surface of neurons and glia regulates synaptic structure and function, while endothelial and macrophage heparan sulfate mediates inflammatory responses. To evaluate the role of glycosaminoglycans in early childhood neurodevelopmental disorders we have generated novel murine disease models carrying global and targeted deletion of heparan sulfate and chondroitin sulfate biosynthetic genes. By using a multidisciplinary approach encompassing biochemistry, cell biology, animal behavior and molecular genetics we are extracting phenotypes that are glycosaminoglycan-dependent. Findings from my research have the potential to identify novel therapeutic targets for childhood neurological disorders and provide further insight into the function of glycosaminoglycans in the normal and diseased brain. Techniques: In vivo studies in mice, isolation of primary neurons, astrocytes and endothelial cells from mice, purification of glycosaminoglycans and structural analysis by liquid chromatography/ mass spectrometry, Western blotting, immunoprecipitation, molecular biology, brain histology and immunohistochemistry, confocal microscopy.

Picture of Sabrina Etzold

Project Title

Postnatal development of intestinal mucosal glycosylation.

Project Description

The epithelial surface of the gut is lined by glycans constituting the glycocalyx or the mucus layer separating the host from the intestintal microbiota. The mucus layer not only protects against bacterial invasion but also provides a habitat and attachment sites for gut microbes. The diverse microbial community has a great impact on human health especially early in life promoting normal gut physiology and immune maturation. Alterations in mucosal glycosylation coincide with intestinal inflammation and abnormal microbial colonization. My project aims to understand how GI glycosylation matures after birth and how mucosal glycosylation and microbial colonization impact each other. Techniques: ex vivo intestinal enteroid model, in vivo gnotobiotic mice model, RT-qPCR, MS glycan analysis

Anel Lizcano Headshot

Project Title

The role of High Molecular Weight Hyaluronan in health and infection

Project Description

My project focuses on identifying the role of High Molecular Weight Hyaluronan (HMWHA) and its interactions with Siglecs (Sialic acid-recognizing immunoglobulin-like lectins) during homeostasis and infectious disease. Techniques:Western blot, ELISA, bacterial Molecular Cloning, protein purification, Confocal Microscopy, bacterial adhesion assays, cell culture, bacterial biofilm formation, Streptococcus pneumoniae pathogenesis, in vivo studies in mice.

Daniel Sandoval

Project Title

The Endothelial Heparan Sulfate Interactome

Project Description

Heparan sulfate proteoglycans present on the cell surface of endothelial cells mediate a wide range of glycan-protein interactions. The sum of these interactions is termed the heparan sulfate interactome. The following objectives of my project are aimed at unravelling the endothelial heparan sulfate interactome. 1) Using RNAseq, we are examining global changes in gene expression that occur between brain microvascular endothelial cells from wild-type and mutant mice bearing deficiencies in unique heparan sulfate biosynthetic enzymes to identify heparan sulfate dependent signaling pathways. 2) Identify novel endothelial HSBPs using heparin chromatography and LC-MS/MS. Currently, studies are underway to clone, express and purify recombinant candidate proteins for further characterization of their heparan sulfate interactions. These results will increase our understanding of the endothelial heparan sulfate interactome by identifying novel heparan sulfate dependent signaling pathways and HSBPs which may define new targets for treating vascular related diseases. Techniques:loning, protein purification, FPLC, endothelial cell isolation, western blot, immunoprecipitation.

Shoib Siddiqui Headshot

Project Title

Role of CD33-related Siglecs in innate immune-editing and progression of cancer

Project Description

Cancer cells are usually recognized by the immune system, as they tend to express altered protein antigens on their surface and this immune recognition might restrict the growth of tumor to some extent. However, cancer cells have many additional molecular processes that help them to bypass/overcome/counteract the host immune system. Thus, ‘Cancer Immunoediting’ results in cancer cells developing resistance, evading cancer immunosurveillance by selection of less immunogenic clones. The role of adaptive immune response in immunoediting of the cancer clones/cells is extensively studied but the role of innate immune cells (other than NK cells) in this process has remained largely unexplored. In this regard, we proposed to decipher the role(s) of Siglecs, which are inhibitory or activating receptors widely expressed by innate immune cells, in cancer immunosurveillance and immunoediting. Techniques:Cell culture, in vivo studies in mice, fluorescence microscopy, qPCR, immunofluorescence staining.

Eillen Tecle Headshot

Project Title

Elucidating the role of sialic acid in modulating female immunity in response to mating.

Project Description

The roles of glycans during fertilization and early embryonic events form an established and well-studied aspect of glycobiology. However, there is a substantial deficit in our understanding of the glycobiology of pre-zygotic events and reproductive compatibility. Many individuals that exhibit defects in fertility have documented problems in these pre-zygotic processes. Glycans decorate cells of the female reproductive tract (including the ovum) and sperm. The monosaccharide sialic acid is located at the terminal end of N-glycans. In mammals, sialic acid is found in two major forms: N-glycolyneuraminic acid (Neu5Gc) and N-acetylneuraminic acid (Neu5Ac). Humans, unlike chimpanzees or mice, lack Neu5Gc. However, humans do harbor antibodies against Neu5Gc due to incorporation of this non-human sialic acid from red meat and cow dairy products. Work in the Gagneux has implicated sialic acid as a major player in reproductive compatibility in vivo as mice with incompatible sialic acid profiles have reduced fertility. Mice can be modified to express only Neu5Ac and anti Neu5Gc antibodies. When these modified female mice are and mated to wildtype males (whose sperm contains Neu5Gc) there is a significant decrease in the litter size as compared to controls. While there is evidence to implicate pre-zygotic effects, specifically the female immune response to sperm, for this decrease in litter size, the mechanism by which sialic acid functions in reproductive compatibility is unknown. The goal of my post-doctoral research is to investigate and determine the role of female supplied sialic acids, sialidase (sialic acid specific hydrolases) and Siglecs (sialic acid binding Ig-like lectins) in female specific immunity and reproductive compatibility. Techniques:Immunostaining, cell culture, confocal microscopy, estrus staging of mice, ELISA, C. elegans research (including multiple behavioral assays, genetic analysis, microinjections and immunohistochemical staining).

Former Trainees