Krüppel expression during postembryonic development of Drosophila.
The Drosophila gap gene Krüppel (Kr) codes for a Zn2+ finger transcription factor important in embryo patterning, segment identity, and specification of various cell types. Based on Northern blot analysis, Kr function has been thought to be restricted to embryogenesis. I report here that Kr is also expressed during larval development, primarily in the fat body. Using both a P-element enhancer-trap line and a portion of the Kr promoter fused to lacZ, I find the activation of Kr in the fat body does not begin until the early-third-instar stage. Earlier in larval development, Kr is detected in the nerve cells associated with the gut. Kr's role as a transcription factor during early embryogenesis is well established. After gastrulation Kr protein is detected in a variety of cell types and is probably involved in cell specification. Kr is not detected in fat cells during embryogenesis nor during the first- and second-instar stages. The delayed expression of Kr in the fat cells occurs at a time in which the larva is undergoing a reprogramming in preparation for metamorphosis. It is possible that Kr serves as a transcriptional regulator in the fat body in this last larval instar. During this last larval stage, several fat-body-specific genes are transcriptionally activated in response to increasing levels of ecdysone. The possible role of Kr in the expression of these ecdysone-regulated genes is discussed.
Hoshizaki
D K
DK
Department of Biochemistry, University of Illinois at Chicago 60612.
D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D004330:Drosophila / Q000196:embryology* / Q000235:genetics*; D029721:Drosophila Proteins; D051741:Kruppel-Like Transcription Factors; D008969:Molecular Sequence Data; D012097:Repressor Proteins; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology; D016335:Zinc Fingers; D001616:beta-Galactosidase / Q000378:metabolism
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C497244:Kr protein, Drosophila; D051741:Kruppel-Like Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors; D001616:beta-Galactosidase