Req: Definition of a promoter showing tissue specificity

Eric H. Mercer Mercer at
Wed Nov 23 00:14:38 EST 1994

In article <leach-211194121158 at>,
leach at (Martin Leach) wrote:

> could anyone post what the scientific community would require to show that
> a promoter shows tissue specificity..

  It depends on how convincing you want to get.

1. Specificity in immoralized cell culture doesn't mean much.  It means
    there are SOME tissue-specific enhancers functioning, but that
    doesn't prove that you've got all the relevant ones.
2. Specificity in transgenic mice, looking at three or more lines, and
    showing that the majority of lines show a transgene pattern
    identical to the endogenous gene, is good proof.  Watch carefully for
    those papers with just one line characterized, or who found only
    one line in five shows the correct pattern. Those constructs are
    missing important elements.
3. When you want to go beyond the call of duty, do it again in transgenics
    with a second reporter gene.  There are NO completely benign reporters
    although lacZ comes close.  On the other hand, there's a report of
    a tyrosine hydroxylase promo that works great driving a growth
    hormone structural gene, but bombs with lacZ.  By the way, nobody does
    step three; it's not worth the effort.

  A good transgene promoter is hard to find, although you wouldn't think
so reading some of the papers out there claiming they've got one based on
one transgenic line.  Yeesh.

Eric H. Mercer                  California Institute of Technology
Division of BIology; 216-76     Pasadena, CA  91125
(818) 356-6822                  mercer at

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