Aj. Andres et P. Cherbas, TISSUE-SPECIFIC REGULATION BY ECDYSONE - DISTINCT PATTERNS OF EIP28 29 EXPRESSION ARE CONTROLLED BY DIFFERENT ECDYSONE RESPONSE ELEMENTS/, Developmental genetics, 15(4), 1994, pp. 320-331
The Eip28/29 gene of Drosophila is an example of a tissue- and stage-s
pecific ecdysone-responsive gene, lis diverse patterns of expression d
uring the third larval instar and a synopsis of those patterns in term
s of expression groups have been reported previously. Here we have stu
died the expression (in transgenic flies) of reporter genes controlled
by Eip28/29-derived flanking DNA. During the middle and late third in
star, most tissues exhibit normal expression patterns when controlled
by one of two classes of regulatory sequences. Class A sequences inclu
de only 657 Np of 5' flanking DNA from Eip28/29. Class B sequences inc
lude an extended 3' flanking region and a minimal (less than or equal
to 93 Np) 5' flanking region. The class B sequences include all those
elements known to be important for ecdysone induction in cultured cell
s. They are sufficient to direct the normal premetamorphic induction o
f Eip28/29 in the lymph glands, hemocytes, proventriculus, and Malpigh
ian tubules. This is consistent with our suggestion that Kc cells are
derived from embryonic hematopoietic cells. It is remarkable that the
epi dermis requires only class A sequences. These are sufficient to vp
-regulate expression at mid-instar and to down-regulate expression at
metamorphosis. It follows that the epidermis uses EcREs distinct from
those that function in Kc cells. ii is possible that the Upstream EcRE
, which is nearly silent in Kc cells, is active in the epidermis. (C)
1994 Wiley-Liss, Inc.