About

Zebrafish provide an unparalleled model organism for studying genes and molecular signaling pathways involved in vertebrate development, diseases such as cancer, as well as neurological disorders. These small tropical fish, popular with aquarium hobbyists, are hardy and easily kept in large numbers in the lab. Because they are vertebrates, they have many of the same genes, tissues and organ systems as humans. Zebrafish embryos are easily obtainable in large numbers (thousands per year), externally fertilized, transparent, and undergo rapid organogenesis. These characteristics enable a wide-range of experimental manipulation including: 1) gene editing using CRISPR/Cas9 and TALAN technologies; 2) generating transgenic fish by DNA injection; 3) altering gene expression by injection of antisense oligonucleotides, mRNA, or DNA; 4) forward genetic screening; 5) chemical screening; and 6) cell/tissue transplantation, including xenotransplantation. The effects of experimental manipulations can then be directly visualized, often in the living animal, because the embryos and adults are transparent.

The Glasgow lab studies cancer and brain development using zebrafish. In addition, we provide expertise and access to this powerful animal model through:

1. Georgetown Lombardi Shared Resources.

2. Mid-Atlantic Shared Services Consortium, which includes the University of Maryland, Johns Hopkins University, and the University of Virginia.

3. Science Exchange, for outside investigators.

Projects

1) Cancer cell invasion and metastasis assessed in zebrafish xenograft models.

Human and murine cancer cells can be transplanted into zebrafish embryos (xenografts) to evaluate tumor cell behavior in vivo. Zebrafish xenografts provide reliable in vivo assays of invasive and metastatic behaviors, tumor cell response to pathway manipulation, and effects of anti-metastatic drugs. There are several advantages of the zebrafish human tumor xenograft assay: 1) the in vivo behavior of fluorescently labeled tumor cells can be directly observed in the transparent zebrafish larva from initial injection to intravasation and migration, extravasation and invasion, and formation of secondary metastases; 2) the assay is rapid, taking only five days from the time of tumor cell injection to obtain the results; 3) a relatively high number of animals can be analyzed, allowing for statistical verification.

Clinically, tumor-cell heterogeneity and adaptability present daunting impediments to treatment. Targeted and combinatorial treatments are being actively pursued to overcome drug resistance, however, determining which treatment will work best for which primary tumor, metastasis or recurrence is problematic. Our long-term goal is to develop a zebrafish xenograft assay for rapidly evaluating drug responses of biopsies from individual tumors in an in vivo setting.

2) Molecular genetic basis of brain development: Oxytocin.

Oxytocin, the “hormone of love”, is associated with a wide range of physiological and behavioral responses. Release of oxytocin directly into the peripheral circulation from neuro-hemal sites in the posterior pituitary results in uterine contraction and milk let-down. In addition, oxytocin functions as an anabolic bone hormone. In the central nervous system, oxytocin affects several behaviors including: 1) feeding and ingestive behavior (as well as gastric motility); 2) pain perception; 3) stress and anxiety; 4) learning and memory; and 5) sexual and social behaviors. Consequently, defects of the oxytocin system are associated with several neuropsychiatric disorders, particularly autism, schizophrenia, Prader-Willi syndrome, depression, anorexia and obsessive-compulsive disorders.

We have identified five transcription factors required for oxytocin cell development. In addition, we discovered that embryonic alcohol exposure leads to oxytocin up-regulation in the hindbrain, a novel finding with implications for understanding alcoholism and other addictive disorders. Further, we have shown interaction of thyroid hormone disruption with oxytocin cell development. The oxytocin system may be particularly susceptible to environmental and genetic perturbation during embryonic development, with profound consequences for behavioral health of children, teens and adults.

3) Transcriptional regulation of Wnt/β-catenin signaling in development, regeneration and cancer.

The Wnt/β-Catenin pathway regulates stem cell pluripotency and cell fate decisions during development, and is a central player in regeneration and cancer. The regulation of target genes by β-Catenin requires a multi-protein coactivator complex, Mediator, which bridges gene regulatory regions with the general transcriptional machinery and RNA polymerase. A regulatory component of Mediator, called the CD8 module, may effect gene activation or repression under specific regulatory states. Using zebrafish, we are investigating the role of the CD8 module in modulating Wnt/β-Catenin pathway regulated gene expression in a variety of in vivo cellular contexts.

Partnerships