Upstream activating sequence

About: Upstream activating sequence is a research topic. Over the lifetime, 1633 publications have been published within this topic receiving 100112 citations.

A zinc-finger fusion protein refines Gal4-defined neural circuits.

Abstract: The analysis of behavior requires that the underlying neuronal circuits are identified and genetically isolated. In several major model species—most notably Drosophila—neurogeneticists identify and isolate neural circuits with a binary heterologous expression-control system: Gal4–UASG. One limitation of Gal4–UASG is that expression patterns are often too broad to map circuits precisely. To help refine the range of Gal4 lines, we developed an intersectional genetic AND operator. Interoperable with Gal4, the new system’s key component is a fusion protein in which the DNA-binding domain of Gal4 has been replaced with a zinc finger domain with a different DNA-binding specificity. In combination with its cognate binding site (UASZ) the zinc-finger-replaced Gal4 (‘Zal1’) was functional as a standalone transcription factor. Zal1 transgenes also refined Gal4 expression ranges when combined with UASGZ, a hybrid upstream activation sequence. In this way, combining Gal4 and Zal1 drivers captured restricted cell sets compared with single drivers and improved genetic fidelity. This intersectional genetic AND operation presumably derives from the action of a heterodimeric transcription factor: Gal4-Zal1. Configurations of Zal1–UASZ and Zal1-Gal4-UASGZ are versatile tools for defining, refining, and manipulating targeted neural expression patterns with precision.

The Role of Sp Family Members, Basic Krupple-Like Factor, and E Box Factors in the Basal and IFN-γ Regulated Expression of the Human Complement C4 Promoter

Abstract: The fourth component of human complement (C4) is a serum protein that is expressed in the liver and other organs. The promoter region of the C4 gene has been analyzed in reporter gene assays in two cell lines that represent hepatic (HepG2) and monocytic (U937) lineages. Analysis indicated that regions important for basal transcription in HepG2 cells included Sp1 and E box sites within the first 100 bp upstream of the transcription initiation site but not the nuclear factor-1 site important in the control of the mouse C4 gene. Also, a region encompassing −468 to −310 was able to repress activity 2-fold. However, when a CACCC or GT box sequence at −140 was mutated the repressive activity of the upstream region resulted in almost no activity. The −140 region consists of a series of four closely positioned GT boxes that were shown to bind Sp1, Sp3, and basic Krupple-like factor in EMSA. This novel two-part regulatory element may be involved in the regulated expression of C4. However, IFN-γ a major activator of C4 expression did not signal through this two-part regulatory element. We were able to map the position of an IFN-γ responsive element in U937. IFN-γ was able to increase transcription by up to 20-fold with mutations in the E box sequence at −78 to −73, thus completely abolishing induction. We conclude that the E box binding factors, which appear to be distinct from upstream stimulatory factors 1 and 2, are totally responsible for IFN-γ induction of C4.