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.

AG4 sequence within PHR1 promoter acts as a gate for cross‐talks between damage‐signaling pathway and multi‐stress response

Abstract: Rph1 and Gisl are damage-responsive repressors involved in PHR1 expression. They have two H/ sub 2/ zinc finger motifs as putative DNA binding domains and N-terminal conserved domain with unknown function. They are also found in the human retinoblastoma binding protein 2 and the mouse jumonji- encoded protein. The repressors are able to bind to A sequence within a 39-bp sequence called upstream repressing sequence of PHR1 promoter (UR ) responsible for the damage-response of PHR1. We report here that Rph1 is predominantly localized in the nucleus as examined by fluorescence microscopic analysis with GFP-Rph1 fusion protein. On the basis of the fact that the A sequence that is recognized by Rph1 and Gisl is also recognized by Msn2 and Msn4 in a process of stress response, we a1so tried to examine the in vivo function of A and the role of Msn2 and Msn4 in PHR1 expression. Our results demonstrate that Msn2 and Msn4 are actually required for the basal transcription of PHR1 expression but not for its damage induction. When A sequence was inserted into the minimal promoter of the cyc1-LacZ reporter, the increased LacZ expression was observed indicating its involvement in transcriptional activation. The data suggest that the A is primarily required for basal transcriptional activation of PHR1 or CYC1 promoter through the possible involvement of Msn2 and Msn4. However, since the A is also involved in the repression of PHR1 via Rphl and Gisl, it is proposed that A functions as either URS or upstream activating sequence (UAS) depending on the promoter context.t.

Knockdown transgenic Drosophila and Parkinson's disease

Abstract: In 2000, by using the binary galactose 4 (GAL4)/upstream activating sequence (UAS) system, Feany and Bender were the first to report a transgenic Drosophila melanogaster fly model expressing familial Parkinson's disease (PD)-linked mutants (Alanine53Treonine and Alanine30Proline) of human alpha-synuclein. Amazingly, these mutant Drosophila (as was not the case with normal Drosophila) replicated the essential features of human PD including adult-onset loss of dopaminergic neurons, filamentous intraneuronal inclusions containing alpha-synuclein, and locomotor dysfunction. We provide highlights in the history of Drosophila PD research with special attention paid to the knockdown transgenic Drosophila GAL4/UAS RNA interference system to characterize and understand the response of mutant parkin, dj-1β, and Lrrk flies to oxidative stress phenomena induced by PQ2+ intoxication, thereby exploring potential therapeutic treatments.

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.

Novel insights into the epigenetic regulation of Plasmodium falciparum virulence genes

Abstract: Plasmodium falciparum malaria still places a major health burden upon the developing world. The high virulence of this parasite is linked to the variegated expression of single P. falciparum erythrocyte membrane protein 1 (PfEMP1) variants that are encoded by the var gene family. Most vars and other virulence genes implicated in host-parasite interactions are found within transcriptionally inert chromatin domains at the nuclear periphery and are associated with heterochromatin protein 1 (PfHP1). Mutually exclusive gene activation relies on the escape of a single var locus from this repressive environment into a transcriptionally competent perinuclear zone and non-coding elements play an essential role in this process. The exact mechanisms involved in singular gene choice, however, remain elusive. Using a transfection-based approach we identified cis-acting regulatory promoter elements, namely an upstream activating sequence and a mutual exclusion element (MEE), which are essential for var gene induction and singular locus recognition, respectively. Interestingly, in absence of the MEE, active var promoters are no longer introduced into the mutual exclusion programme. A yet unknown nuclear factor binds specifically to the MEE and I consider this interaction to be a prime candidate for the regulation of singular var activity. In addition, the MEE regulates PfEMP1 expression post-transcriptionally. On the mRNA level, this element is able to drastically reduce translation in an autonomous manner. In an independent project, I generated a conditional PfHP1 loss-of-function mutant to functionally characterise this epigenetic regulator. After inducing PfHP1 depletion during early intra-erythrocytic development, parasites progress normally through schizogony but do not enter mitosis in the subsequent generation. Detailed analysis of these PfHP1-deprived parasites revealed four striking phenotypes: (1) they show a massive de-repression of PfHP1-controlled virulence genes, including the entire var repertoire; (2) over 50% of the cells in the parasite population represent viable early stage gametocytes that complete sexual development in absence of PfHP1; (3) this high conversion rate is linked to the induction of an apiap2 TF family member during schizogony of the previous cell cycle; (4) the non-gametocyte cells represent asexual parasites that are reversibly arrested prior to enter S-phase and mitosis. We could thus identify essential roles for PfHP1 in gene silencing, cell cycle progression and showed for the first time that the mechanism of sexual conversion involves a strong epigenetic component.