TY - JOUR
T1 - Identification of a strong transcriptional activator for the copia retrotransposon responsible for its differential expression in drosophila hydei and melanogaster cell lines
AU - Cavarec, Laurent
AU - Jensen, Silke
AU - Heidmann, Thierry
PY - 1994/8/30
Y1 - 1994/8/30
N2 - We have characterized the regulatory properties of a 72bp sequence located in the 5′ untranslated domain of the Drosophila copia retrotransposon, 3′ to the left LTR, by transient transfection assays with cell lines derived from either Drosophila hydei (DH33 cells) or Drosophila melanogaster (Schneider II and Kc cells). Reporter plasmids were constructed which contained the lacZ gene under the control of either the entire copia LTR with 5′ untranslated domain, or a minimal heterologous promoter flanked with the identified copia regulatory sequences. Upon transfection into the copia-free DH33 cells, the presence of the 72bp sequence resulted for all reporter plasmids in a 100-700 fold increase in expression level -as well as in reporter gene RNA levels- whereas this sequence had no enhancing effect upon transfection of the same plasmids into the copia-containing Schneider II or Kc cells. Moreover, mobility shift assays with the 72bp enhancer sequence disclosed two specific bands of retarded mobility with whole-cell extracts from DH33 cells, whereas no retarded band could be detected, under identical conditions, with extracts from Schneider II cells. UV crosslinking experiments between the enhancer sequence and DH33 extracts revealed a single protein species -of app. mel. wt. 50kD- for both retarded bands, thus strongly suggesting that they simply correspond to the sequential binding of two identical factor molecules to the enhancer sequence. These data demonstrate that the copia-free D. hydei cells express a strong transcriptional activator for the copia element and possible interpretations for the absence of this factor in the copia-containing D. melanogaster cells are discussed in terms of a possible "adaptation" of the "host" (D. melanogaster) to an otherwise highly mutagenic "parasite" (copia with its transcription factor).
AB - We have characterized the regulatory properties of a 72bp sequence located in the 5′ untranslated domain of the Drosophila copia retrotransposon, 3′ to the left LTR, by transient transfection assays with cell lines derived from either Drosophila hydei (DH33 cells) or Drosophila melanogaster (Schneider II and Kc cells). Reporter plasmids were constructed which contained the lacZ gene under the control of either the entire copia LTR with 5′ untranslated domain, or a minimal heterologous promoter flanked with the identified copia regulatory sequences. Upon transfection into the copia-free DH33 cells, the presence of the 72bp sequence resulted for all reporter plasmids in a 100-700 fold increase in expression level -as well as in reporter gene RNA levels- whereas this sequence had no enhancing effect upon transfection of the same plasmids into the copia-containing Schneider II or Kc cells. Moreover, mobility shift assays with the 72bp enhancer sequence disclosed two specific bands of retarded mobility with whole-cell extracts from DH33 cells, whereas no retarded band could be detected, under identical conditions, with extracts from Schneider II cells. UV crosslinking experiments between the enhancer sequence and DH33 extracts revealed a single protein species -of app. mel. wt. 50kD- for both retarded bands, thus strongly suggesting that they simply correspond to the sequential binding of two identical factor molecules to the enhancer sequence. These data demonstrate that the copia-free D. hydei cells express a strong transcriptional activator for the copia element and possible interpretations for the absence of this factor in the copia-containing D. melanogaster cells are discussed in terms of a possible "adaptation" of the "host" (D. melanogaster) to an otherwise highly mutagenic "parasite" (copia with its transcription factor).
UR - http://www.scopus.com/inward/record.url?scp=0027930437&partnerID=8YFLogxK
U2 - 10.1006/bbrc.1994.2195
DO - 10.1006/bbrc.1994.2195
M3 - Article
C2 - 8074683
AN - SCOPUS:0027930437
SN - 0006-291X
VL - 203
SP - 392
EP - 399
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 1
ER -