Category: Developmental Biology and Congenital Anomalies


Abigail Buchwalter Cool, Ph.D.

 

Research Interests:
We study the mechanisms that govern the specialization and maintenance of nuclear organization across cell types.

Summary:
We seek to understand how the organization of the cell nucleus is established, specialized across cell types, and maintained over time to influence cellular identity. “Nuclear organization” involves the non-random packaging of the genome within the nucleus, but also the assembly and interactions of other nuclear structures, such as the nuclear lamina and the nucleolus.

This work begins with a particular focus on the nuclear lamina, a nuclear structure that is essential for mammalian development and is mutated in ~15 “laminopathy” diseases that afflict the heart, muscle, bone, fat, and nervous system. We focus on three main thematic areas: (i) defining the essential roles that the nuclear lamina plays in nuclear organization, (ii) exploring disruption of nuclear organization as a possible cellular mechanism of aging, and (iii) determining how nuclear organization is maintained (or alternatively, remodeled) over time.

 

 

 


Vasanth Vedantham, M.D.

Research Interests: Development and function of the cardiac conduction system; molecular regulation of cardiac pacemaker cells; mechanisms of cardiac arrhythmias

 

Our lab is focused on cardiac pacemaker cells, specialized cardiomyocytes whose autonomous electrical activity allows the sinoatrial node to serve as the heart’s natural pacemaker. Specific questions include: How are pacemaker cells different from regular heart cells at the level of gene expression and regulation? How does their unique gene expression signature confer their distinctive electrophysiological properties? How have selection pressures generated functional differences in pacemaker cells among different vertebrate species? What are the molecular mechanisms that guide pacemaker cells to integrate electrically with the rest of the heart to form a node? How do pacemaker cell biology and function change in response to physiological and pathological stress? What is the mechanistic link between sinus node dysfunction and atrial fibrillation? Our approaches include mouse genetics, whole-animal and ex-vivo electrophysiology, cellular and molecular electrophysiology, gene expression analysis, and bioinformatics. Ultimately, we hope to design novel treatments for patients suffering from heart rhythm disorders, including sinus node dysfunction and atrial fibrillation

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David R Raleigh, M.D.

Research Interests: Hedgehog signaling, developmental biology, brain tumors and molecular therapeutics

 

More children die from brain tumors than any other type of cancer, and the most common type of brain tumor in children is medulloblastoma. Like all cancers, medulloblastoma is caused by uncontrolled cell growth. Approximately one-third of medulloblastoma cancers arise when a particular signal that tells brain cells to grow, called Hedgehog, gets stuck in the “on” position. We are interested in uncovering exactly how Hedgehog signals tell cancer cells to grow. To do so, we are investigating how the Hedgehog pathway is activated, and how Hedgehog activation regulates the expression of other signals to influence cell growth. Understanding how Hedgehog signals cause cancer may show us how to turn off these signals, and potentially, lead to new therapies for medulloblastoma.

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Rong Wang, Ph.D.

Rong Wang photo copy

Research Interests:
Molecular Regulation of Mammalian Arterial Venous Specification

Summary:

Molecular Regulation of Arterial-Venous Programming in Development and Disease   

 

Research in my lab is focused on angiogenesis, or new blood vessel formation, which is a critical process in development and disease. My lab aims to advance the fundamental understanding of the cellular, molecular, and hemodynamic mechanisms underlying arterial-venous programming in normal and pathological angiogenesis. We use cutting-edge mouse genetics to delete or express genes in a cell lineage-specific and temporally controllable fashion in endothelial cells. This advance is crucial for the study of candidate genes in vascular function, especially when combined with sophisticated 5D two-photon imaging (3D + blood flow over time). These innovative approaches provide us with exceptional access to gene function in both healthy and pathological conditions in living animals. This basic approach is complemented by preclinical studies with patient samples in addition to our mouse models of disease. In particular, we investigate the molecular regulators governing arterial-venous programming – particularly the Notch, ephrin-B2, and TGF-beta signaling pathways – in both normal and pathological conditions.

 

 

Ongoing projects:

 

Vascular Development.  Our lab aims to identify molecular regulators of arterial and venous cell fate determination and morphogenesis in embryonic development. We primarily focus on the origin and morphogenesis of the dorsal aorta and cardinal vein, the first major artery-vein pair to form in the body.

 

Arteriovenous Malformation (AVM).  AVMs are severe vascular anomalies that shunt blood directly from arteries to veins, displace intervening capillaries, and bypass tissues. My lab studies the pathogenesis and regression of AVMs. We have a long history of investigation using animal models into Notch-mediated AVM pathogenesis as well as into potential treatments for the disease.

Arterial occlusive diseases and arteriogenesis.  The body responds to arterial occlusions by inducing arteriogenesis, or radial enlargement of arteries, to restore circulation to blood-deprived tissue. We are investigating pro-arteriogenic molecular regulators to uncover potential therapeutic targets, which may be used to enhance the body’s natural defense against arterial occlusive disease.

Cancer. Solid tumors induce arteriogenesis to support their growth. We investigate the molecular stimulators of arteriogenesis in tumor progression and regression, particularly in hepatocellular carcinoma (HCC), which is characterized by large and highly arterialized tumor masses in the liver. We study genes regulating tumor arterial growth and modify these genes to target tumor arterial supply and to inhibit HCC growth.

Ultimately, through these distinct but interconnected fields of study, we hope to identify novel drug targets and inform rational design of new therapeutics to treat human disease.

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Deepak Srivastava, M.D.

Srivastava

Research Interests:
Developmental biology, pediatric cardiology, congenital heart defects, organogenesis, human genetics, stem cells, cardiac repair

Summary:
Dr. Srivastava’s work focuses on understanding cardiac development by elucidating the molecular events regulating early and late developmental decisions that instruct progenitor cells to adopt a cardiac cell fate and subsequently fashion a functioning heart. This foundation has been used to discover the genetic basis for some congenital heart malformations.

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Xiaokun Shu, Ph.D.

Shu

Research Interests:
Protein Rational Design and Directed Evolution for Biology and Medicine

Summary:
We are developing technologies to bridge the gap between clinical medicine and molecular biology. Their successful use in biomedicine will significantly improve treatment of disease.

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Nelson B Schiller, M.D.

Schiller

Research Interests:
Dr. Schiller specializes in the use of echocardiography in the diagnosis and treatment of heart disease. His research interests center around the quantitation of left ventricular function by quantitative two-dimensional echocardiography and Doppler.

Summary:
Measuring the heart has been a preoccupation of civilizations since ancient Egypt. Measuring the heart using noninvasive techniques that are free of ionizing radiation has riveted the attention of modern medicine because knowledge of the size of the heart’s anatomic parts provides powerful diagnostic and therapeutic information. Dr. Nelson B. Schiller a member of the Department of Medicine, Cardiology Division, CVRI and John J. Sampson-Lucie Stern Endowed Chair in Cardiology, has spent his career investigating the application of echocardiography to the precise measurement and clinical application of the volume, weight and hemodynamics of the chambers and valves of the heart. His work is currently centered on the Heart and Soul Study (Mary Whooley, MD PI), where echocardiography measurements are being related to outcomes of heart disease.

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Jason R. Rock, PhD

Rock

Research Interests:
Stem cells in lung development, maintenance, and disease

Summary:
We investigate how the many epithelial and stromal cell types of our lungs are generated during development, maintained for a lifetime and regenerated following injury. To do this, we use in vivo and in vitro models to identify and test the progenitor capacity of putative stem cell populations. We posit that aberrant stem cell behaviors explain many features of common lung diseases such as mucous cell hyperplasia and pulmonary fibrosis. For this reason, we study the molecular mechanisms and environmental influences (i.e., niche) that regulate the division and differentiation of stem cells along various lineages. Our ultimate goal is to identify genetic, molecular and cellular therapies for the treatment of lung disease.

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Jeremy F Reiter, M.D., Ph.D.

Reiter

Research Interests:
Signaling, primary cilium, stem cell, Hedgehog, Wnt

Summary:
In the process of development, a single egg cell develops into a complex organism. Understanding how that first cell generates such astonishing complexity is one of biology’s great tasks. Not only is this task fundamental to our understanding of ourselves, but it is also critical to understanding the causes of birth defects and other diseases. Many of the mechanisms underlying development depend on intercellular communication, the ability of cells to send and receive information. Secreted signaling proteins can communicate many different types of information, from what type of cell a cell should become to whether a cell should live or die. We are studying the mechanisms by which a cellular organelle, the primary cilium, receives and interprets these signals during development. We are also studying how mistakes in these signals contribute to diseases such as cancer.

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Keith E Mostov, M.D., Ph.D.

Mostov

Research Interests:
Polarized epithelial membrane traffic and epithelial morphogenesis.

Summary:
How do individual cells organize to form a multicellular tissue? An individual cell can exhibit many different behaviors – proliferation, migration, adhesion, polarization, differentiation, and death. But to build a tissue, a population of cells must coordinate these individual behaviors across space and time. Little is understood about the mechanisms that orchestrate the actions of single cells during morphogenesis. To analyze these issues, we are studying how epithelial cells form three-dimensional organs. Epithelia are coherent sheets of cells that form a barrier between the interior of the body and the outside world. Internal epithelial organs contain two types of building blocks, cysts and tubules. Our experimental strategy uses culture of epithelial cells in a three-dimensional extracellular matrix. Single cells plated in matrix grow to form hollow cysts lined by a monolayer of cells. We have discovered a pathway containing the small GTPase, rac1, alpha1-beta3 integrin, and laminin, which coordinates cell polarity, so that apical surfaces of the cells are all oriented towards the cyst lumen. Cysts are remodeled into by growth factors, which cause transient dedifferentiation and migration, followed by redifferentiation into polarized epithelial cells lining the tubule.

Spatial asymmetry is fundamental to the structure and function of most eukaryotic cells. A basic aspect of this polarity is that the cell’s plasma membrane is divided into discrete domains. The best studied and simplest example of this occurs in epithelial cells, which line exposed body surfaces. Epithelial cells have an apical surface facing the outside world and a basolateral surface contacting adjacent cells and the underlying connective tissue. These surfaces have completely different compositions. Epithelial cells use two pathways to send proteins to the cell surface. Newly made proteins can travel directly from the trans-Golgi network (TGN) to either the apical or basolateral surface. Alternatively, proteins can be sent to the basolateral surface and then endocytosed and transcytosed to the apical surface. We are studying the machinery that is responsible for the specificity and regulation of polarized membrane traffic in epithelial cells. I will discuss several recent results.
1. The SNARE hypothesis provides a unified model for how intracellular vesicular targeting and fusion work. Proteins on transport vesicles, known as v-SNAREs, pair with corresponding t-SNAREs on target membranes, leading to vesicle fusion. The correct pairing of particular v- and t-SNAREs can provide a mechanism for specificity of targeting and fusion. Polarized epithelial cells are an ideal system in which to test the role of SNAREs in specificity, as these cells contain two plasma membrane targets, the apical and basolateral surfaces, as well as multiple classes of vesicles traveling to each surface. We have found that that the t-SNARE syntaxin 3, is involved with transport to the apical surface, while the related t-SNARE, syntaxin 4, is utilized for transport to the basolateral surface.
2. The polymeric immunoglobulin receptor (pIgR) transcytoses IgA from the basolateral to the apical surface. Transcytosis is stimulated by ligand binding. Binding of IgA causes dimerization of the pIgR, which leads to activation of a non-receptor tyrosine kinase, p62Yes. Mice knocked out for this kinase are deficient in IgA transport. Phosphatidylinositol-specific phospholipase C gamma is activated, resulting in production of DAG and IP3. The DAG activates protein kinase Ce, which stimulates transcytosis. The IP3 raises intracellular free calcium, which also stimulates transcytosis. Stimulation of transcytosis also involves the small GTPase, rab3b, which directly interacts with the pIgR.
3. When epithelial cells, such as MDCK cells, are plated in a 3 dimensional collagen matrix, the cells form hollow, polarized cysts with the apical surface facing the lumen of the cyst. Overexpression of a dominant negative form of the small GTPase, rac, retards lumen formation and leads to a partial reversal of polarity, with the apical surface oriented towards the outside of the cyst. Growth of the cysts laminin rescues this phenotype, indicating that interfering with rac function interferes with the ability of the cell to assemble, laminin, which normally provides a spatial cue.
4. When collagen-grown cysts are stimulated with hepatocyte growth factor (HGF), the cysts develop branching tubules, providing a simple model system for studying tubulogenesis. The exocyst is an eight-subunit complex involved in targeting transport vesicles to specific regions of the plasma membrane. We have found that HGF treatment causes the exocyst to relocalize from the region of the tight junction to the growing tubule, indicating that new membrane is being directed to the tubule. Overexpression a subunit of the exocyst, hSec10, causes the cysts to elaborate an increased umber of tubules, indicating a direct connection between membrane traffic and tubulogenesis.

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Takashi Mikawa, M.S., Ph.D.

Mikawa

Research Interests:
Morphogenesis, development, body axis, patterning, cell-to-cell communication, cell architecture, cell fate diversification, cardiovascular system, cardiac conduction system, central nervous system, haemodynamics, growth factor signaling.

Summary:
The establishment of extremely complicated structures and functions of our organ systems depends upon orchestrated differentiation and integration of multiple cell types. Our group focuses to explore a common developmental plan for successful organogenesis, by investigating the mechanisms involved in the differentiation and patterning of the cardiovascular and central nervous systems.

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Thomas B Kornberg, B.A., Ph.D.

Kornberg

Research Interests:
Developmental regulation

Summary:
My laboratory investigates the mechanisms that pattern developing organs. We carry out our studies on the fruit fly, as it offers many advantages with its ready accessibility to histological analysis and the ease with which genetic manipulations can be made. We focus on two systems  the fly wing and the fly lung. Both are model systems that offer opportunities to identify and characterize basic genetic and molecular mechanisms that are relevant to human development and disease.

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