Rochester Oral Biology Research Conference

Speaker Information

Session I: Salivary Gland Development and Maintenance

Co-Chairs: Catherine Ovitt & Kelly Ten Hagen

Monn Myat, Ph.D.
Assistant Professor
Cell and Developmental Biology
Weill Cornell Medical College
Salivary Gland Morphogenesis in Drosophilia
Salivary glands of the Drosophila embryo develop by invagination of primordia from the embryo surface and subsequent migration of the internalized gland. We are investigating the mechanisms by which the salivary gland migrates as a cohesive organ along surrounding mesoderm.   Our studies demonstrate that the gland migrates cohesively through coordinated protrusive activity at the distal tip and contractile activity at the proximal tip concomitant with the assembly and disassembly of integrin- and cadherin-based adhesion complexes.  Through genetic analysis, we identified Rac and Rho small GTPases, p21-activated kinase (Pak), integrins and two novel regulators of integrins as critical components of the signaling pathway that controls these processes.  Our studies of salivary gland migration are beginning to unravel the complex nature by which an intact organ migrates cohesively in vivo. 

 

Kelly Ten Hagen, Ph.D.
Chief, Developmental Glycobiology Unit
NIDCR (National Institute of Dental and Craniofacial Research), NIH
The Role of Mucin-Type Protein Glycosylation During Development
The primary goal of our laboratory is to understand the developmental role of the evolutionarily conserved protein modification known as mucin-type O-linked glycosylation, which is found on proteins that dominate salivary secretions as well as line the digestive, respiratory and urogenital tracts.  We hypothesize that the mucin-type O-linked sugar chains present on secreted and membrane bound molecules would have profound effects on cell adhesion, interaction and signaling cascades occurring during development.   Recent studies of mutations in one glycosyltransferase, provide the first evidence that O-glycosylation is required during embryonic tracheal system development. We found that mutants in this glycosyltransferase displayed abnormal cell size and shape, loss of apicobasal polarity and compromised septate junction formation, leading to a loss of paracellular barrier formation in the tracheal system.  Ongoing studies in both the fly and cell culture are revealing additional roles for O-glycans in many developmental processes.

 

Melinda Larsen, Ph.D.
Assistant Professor of Biological Sciences
University at Albany, SUNY
Cell-Cell and Cell-Matrix Interactions in Salivary Gland Development
Studies using the mouse embryonic submandibular salivary gland organ culture system have revealed that cells undergo cell movements during development, indicating that cell-cell and cell-matrix adhesions are dynamic during branching morphogenesis.  Dynamic remodeling of the basement membrane also appears to be critical for branching to occur. Current studies are focused on identifying molecular mechanisms controlling cell and basement membrane dynamics to facilitate intelligent tissue engineering strategies.

 

Denise Faustman, MD, Ph.D.
Associate Professor
Harvard Medical School
Reversal of Sjögren’s-Like Syndrome from NOD mice to humans?
Non-obese diabetic (NOD) mice exhibit autoimmune diabetes and Sjögren’s like syndrome. We tested if a therapy (injections of splenocytes and complete Freund’s adjuvant) that was reported to reverse diabetes in the NOD mouse would affect their Sjögren’s-like syndrome. Our preliminary data report that a brief intervention into NOD mice with Sjögren’s-like syndrome can reverse salivary gland dysfunction.

 

Catherine Ovitt, Ph.D.
Assistant Professor of Biomedical Genetics
Center for Oral Biology
Univ. of Rochester
Postnatal Salivary Gland Progenitor Cells
Maintenance of salivary gland structure and function in the adult appears to occur by self-renewal of differentiated acinar and duct cells, as well as through the contribution of progenitor cells. The identification of progenitor cells capable of generating the salivary gland cell lineages would be a major step toward the application of cell-based therapies to the treatment of gland dysfunction. A limited population of duct cells in all three major salivary glands is characterized by expression of the transcription factor Ascl3. Lineage analysis shows that these cells act as progenitors of both acinar and ductal cells. Our studies indicate that the Ascl3-expressing cells are important for expansion and maintenance of adult salivary glands.

 

Keynote Speaker- Lawrence A. Tabak Lectureship

Bruce Baum, D.M.D., Ph.D.
Chief, Gene Transfer Section
NIDCR (National Institute of Dental and Craniofacial Research), NIH
Gene Therapy for Radiation-Induced Salivary Gland Damage
My presentation will address our studies to employ gene therapy to prevent, as well as correct, radiation induced salivary gland damage. The preventive approach focuses on the hypothesis that microvascular endothelial cells in the glands are a primary target of radiation, and that transfer of genes  encoding angiogenic factors such as VEGF and bFGF to glands prior to irradiation can minimize gland damage. The corrective approach focuses on transfer of the aquaporin-1 gene to existing radiation damaged glands to facilitate salivary secretion. Preventive studies are currently conducted in pre-clinical animal models, while the corrective approach is currently being studied in the clinic.

 

Session II: Cell Signaling in Epithelial Cells

Co-Chairs: David Yule & Indu Ambudkar

James Sneyd, Ph.D., FRSNZ
Professor of Applied Mathmatics
University of Auckland
Part I – A Systems Biology Approach to Signaling
Mathematical modeling has an important role to play in the study of complex systems such as saliva secretion. In my talks I shall describe the kinds of questions that can be usefully addressed with mathematical models, and the kinds of data that are needed to construct such models. Preliminary results from our current investigations on saliva secretion and its dependence on intracellular calcium dynamics will be discussed.

David Yule, Ph.D.
Associate Professor of Pharmacology and Physiology; of Medicine, Gastroenterology Unit; and in the Center for Oral Biology
Univ. of Rochester
IP3-Ca2+ Signaling
Fluid secretion from salivary acinar cells is dependent on the spatial and temporal characteristics of secretagogue stimulated intracellular Ca2+ signals. These signals are generated following activation of the type-2 and -3 Inositol 1,4,5 trisphosphate receptors (InsP3R). In my presentation I will discuss our recent data investigating the regulation of Ca2+ release through these InsP3R subtypes.

 

 

Trevor Shuttleworth, Ph.D.
Professor of Pharmacology and Physiology
Professor in the Center for Oral Biology
Univ. of Rochester
Ca2+ Entry Pathways
The agonist-activated entry of Ca2+ is essential for sustained secretion of fluid by the parotid gland, and several potential pathways for such entry have been identified. However, their biophysical properties and modes of activation differ, raising the question of which ones are critical for the secretory response, and under what specific circumstances they might operate. Recent advances in the molecular identification of key components in these pathways and their regulation hold the promise of resolving this key question.

 

Stephen Soltoff, Ph.D.
Assistant Professor of Medicine, Department of Medicine
Division of Signal Transduction
Beth Israel Deaconess Medical Center
Salivary Gland Signaling Cascades
Salivary glands have signaling molecules and cascades that also are found in other tissues and cells, and which contribute to normal physiological functions as well as diseases such as cancer.  Among these are the MAPK/ERK (microtubule-associated protein kinase/extracellular signal-regulated kinase) signaling cascade.  New studies suggest that MAPK/ERK signaling in parotid acinar cells interacts reciprocally with the Na,K-ATPase (Sodium Pump), such that Na,K-ATPase activity affects ERK activation as well as the converse, ERK activation affects the Na,K-ATPase activity.  Data supporting this idea will be presented during this talk.

 

Indu Ambudkar, Ph.D.
Chief, Gene Therapy and Therapeutics Branch
NIDCR (National Institute of Dental and Craniofacial Research), NIH
Function of TRP Channels in Ca2+ Entry
Regulated fluid secretion from salivary glands is dependent on calcium entry that is mediated by store operated calcium channels localized in the basolateral plasma membrane region of acinar cells.  The molecular components and regulation of this channel have not yet been conclusively identified.  Our studies address the role of transient receptor potential family of cation channels in salivary gland fluid secretion.  The role of TRPC1 and TRPV4 in fluid secretion and volume regulation will be discussed.

 

Session III: The Epithelial Fluid Secretion Mechanism

Co-Chairs: Ted Begenisich & Shmuel Muallem

Edmund Crampin, DPhil, BSc Hons
Senior Lecturer
Auckland Bioengineering Institute & Department of Engineering Science
University of Auckland
Part II – A Systems Biology Approach to Secretion
Mathematical modeling has an important role to play in the study of complex systems such as saliva secretion. In my talks I shall describe the kinds of questions that can be usefully addressed with mathematical models, and the kinds of data that are needed to construct such models. Preliminary results from our current investigations on saliva secretion will be discussed.

 

James Melvin, D.D.S., Ph.D.
Chair, Center for Oral Biology
Professor of Pharmacology & Physiology
Univ. of Rochester
Cl Channels and Fluid Secretion
Fluid and electrolyte secretion by salivary gland acinar cells is driven by transepithelial Cl- movement. This process is dependent upon activation of an apical Cl channel. The properties of several different types of Cl channels have been characterized in salivary acinar cells, although the Ca2+-activated Cl channel appears to be the key anion channel necessary for secretion. This presentation will provide an update of our current understanding of the functional properties and the molecular identity of Cl channels in salivary acinar cells.

 

Ted Begenisich, Ph.D.
Professor of Pharmacology & Physiology
Professor in the Center for Oral Biology
Univ. of Rochester
K Channel Function / Interaction of Slo and IK1
My talk will include a review of the calcium-activated potassium channels in fluid secreting epithelia including colon and salivary glands.  I'll discuss some of the consequences for fluid secretion of genetically ablating these potassium channels.  We have recently discovered an interaction between these two channels and I will discuss recent experiments designed to uncover the mechanism underlying this interaction.

 

Shmuel Muallem, Ph.D.
Ruth Harrell Professor in Medical Research, Department of Physiology  
UT Southwestern
Mechanism and regulation of HC03-secretion in exocrine gland
Epithelial HCO3- secretion is requires HCO3- influx across the basolateral membrane that is mediated by the Na+-HCO3- co-transporter pNBC1. HCO3- exit across the luminal membrane is mediated by a CFTR-SLC26 transporters complex, where CFTR functions as a Cl- channel and the SLC26 transporters as electrogenic or electroneutral Cl-/HCO3- exchangers. This presentation will discuss the role of each transporter in HCO3- secretion and how events at the basolateral and luminal membranes are coordinated.

 

Marshall Montrose, Ph.D.
Professor and Chair
Dept. of Molecular & Cellular Physiology
Univ. of Cincinnati
Epithelial Barrier and GI Function
All epithelial cells in the GI tract and accessory organs must sustain a barrier to luminal contents while simultaneously providing routes for selective transport (either absorption or secretion) of select molecules. The challenge is heightened in the GI tract because of numerous noxious substances in the lumen, and the rapid turnover of epithelial cells during both physiologic renewal and pathophysiologic damage. Our work has been using in vivo imaging with confocal and two-photon microscopy to study the dynamics of cell replacement in synchrony with the local barrier function that defends the body during such microscopic challenges.

 

Keynote Speaker – William H. Bowen Lectureship

Lawrence Tabak, D.D.S., Ph.D.
Director, National Institute of Dental and Craniofacial Research & Senior Investigator and Chief, Section of Biological Chemistry
National Institute of Diabetes and Digestive and Kidney Diseases, NIH
How Ira’s Protein Led Me Down a Sugar Coated Trail
For my talk, I will trace my interests in mucin biochemistry and focus on the role played by the enzymes that initiate mucin-type O-glycosylation.

 

 

Session IV: Saliva – Biomarkers / Structure and Function

Co-Chairs: Daniel Malamud & Stefan Ruhl

Daniel Malamud, PhD.
Professor of Basic Sciences
NYU College of Dentistry
Update on Oral-Based Diagnostics for Systemic Diseases
The talk will give a brief overview of oral-based diagnostics (what types of samples are used, what types of analytes can be detected, what are the challenges), and then will focus on the program funded by NIDCR to develop  a point of care device.  I will review all of the existing 4 projects, and focus on our own (Oral-based diagnostics for bacterial and viral pathogens).

 

 

Ignacio Sanz, M.D.
Professor of Medicine & Microbiology & Immunology
Chief, Division of Clinical Immunology & Rheumatology
Director, Rochester Autoimmunity Center of Excellence
Univ. of Rochester
B Cells and the Salivary Glands.  Biomarker Applications
Primary SS is an autoimmune disease that progressively damages the exocrine glands with predominant involvement of the salivary and lachrymal glands.  The central pathogenic feature of SS is a lymphocytic infiltrate around the glandular ducts that eventually replaces the acinar epithelium leading to decreased glandular secretions.  Interestingly, many of the extraglandular manifestations of SS also result from a lymphocytic infiltration of the epithelium in the lungs, kidney and biliary tract.  Recent studies have shown that these infiltrates contain a substantial amount of B-cells and plasma cells together with activated CD4+ T helper cells.  Multiple lines of experimental evidence strongly indicate that B-cells are likely to play a central role in the pathogenesis of SS.  Thus, a condition similar to SS with severe sialadenitis, decreased saliva production and destruction of the salivary glands develops in mice with expansion of B-cells due to over-expression of B Lymphocyte Stimulator (BLyS/BAFF) and elevated levels of circulating BLyS have been documented in human SS.   In the human disease, approximately 20% of all infiltrating lymphocytes are B-cells with predominant accumulation of CD27+ memory cells and CD27High plasma cells.  There is strong evidence for both the expansion of oligoclonal populations of B-cells and for the local production of disease-related autoantibodies and it seems likely that these critical pathogenic processes are mediated by the formation within the salivary glands of ectopic germinal center-like structures capable of selecting and expanding and select autoimmune memory and plasma cells in an antigen-drive fashion.  Finally, an important role of B-cells in the pathogenesis of SS is also supported by strong preliminary evidence indicating the clinical efficacy of Rituximab-induced B-cell depletion in the treatment of this condition.

 

Stefan Ruhl, D.D.S., Ph.D.
Assistant Professor, Department of Oral Biology
School of Dental Medicine, SUNY University of Buffalo
A Proteomics-based Search for Bacterial Recognition Sites in Human Saliva
Certain salivary proteins – once adsorbed to mineralized or soft tissue surfaces within the mouth – serve as attachment substrates for oral bacteria, thus enabling them to gain an initial foothold in the oral cavity. In many cases, highly specific recognition of cognate peptide or oligosaccharide motifs in such salivary (glyco)proteins by corresponding adhesin molecules expressed by the bacteria is involved in the attachment of these microorganisms. Proteomics approaches combined with far-Western bacterial overlay techniques will be presented that are suited to map salivary proteins which serve as binding sites for oral commensal bacteria but also for the stomach pathogen Helicobacter pylori.

 

Libuse Bobek, M.A., Ph.D.
Professor, Dept. of Oral Biology
SUNY Buffalo, School of Dentistry
Antimicrobial Activity of MUC7 Peptides
Cationic peptides derived from the N-terminal region of human salivary mucin, MUC7, possess broad-spectrum fungicidal and bactericidal activity in vitro. For example, they are effective against a variety of fungi including C. albicans and C. glabrata, and against gram-positive bacterium S. mutans. Recently, we have demonstrated that MUC7 12-mer-L and D are also effective in vivo, in a mouse model of oral candidiasis, and that both peptides are also capable of preventing the formation of S. mutans biofilm and reduce the preformed S. mutans biofilm. The activities, the possible mechanism of action and the therapeutic potential of these peptides will be presented.

 

Michel Koo, D.D.S., Ph.D.
Assistant Professor of Dentistry
Eastman Dental Center
Assistant Professor in the Center for Oral Biology
Univ. of Rochester
Saliva-Bacterial Interactions - Influences on S. mutans
 Biofilm Formation
Several active enzymes have been identified in salivary pellicles, including lysozyme, amylase and streptococcal glucosyltransferases. This presentation focuses on how the interactions of these surface-adsorbed enzymes may modulate biofilm formation by Streptococcus mutans at physiological, structural and molecular levels.