Biomedical Engineering Reference
In-Depth Information
10
Elucidating Gene Function
through Use of Genetically
Engineered Mice
Mary P. Heyer, Catia Feliciano, Joao Peca and Guoping Feng
Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA
10.1 Introduction
The development of molecular genetics techniques for the direct manipulation of the mouse
genome has revolutionized biological and biomedical research. These techniques are now
in widespread use, with increasingly sophisticated genetic alterations possible. The mouse
genome is the most easily manipulated of all mammals; thus, genetically engineered mice
facilitate detailed
in vivo
analysis of gene function and provide models for a variety of human
disorders. Several methods are available for loss or gain of gene function in mice, including
overexpression, deletion, point mutation and reporter expression, with additional control
through techniques facilitating temporal and spatial restriction of these manipulations. Phe-
notypic consequences of these heritable genetic alterations can be examined within the rich
complexity of the living mouse, yielding insights into gene function in various biological
phenomena and disease states.
Transgenic technology is widely used for gene overexpression
in vivo
through ran-
dom insertion of an exogenous vector DNA sequence after pronuclear injection of mouse
oocytes. This method can be adapted for expression of a reporter gene downstream of a
promoter of interest, while gene function can also be inhibited through overexpression of
dominant-negative mutants. Transgenic technology is relatively straightforward, well estab-
lished and highly efficient, generating founder animals in a relatively short time period. In
some cases, owing to random vector integration, transgene expression patterns and levels
may be affected by neighboring sequences. DNA is often inserted as multiple, concatemer-
ized copies, generating variable expression levels. The injected DNA must contain all the
