Exam 7: Control of Gene Expression

Expression of the Even-skipped (Eve) gene in early Drosophila embryos is under the control of several transcription regulators. In one example, one of the Eve stripes is positioned near the anterior region of the embryo, and its regulatory module contains binding sites for Bicoid and Hunchback (activators) as well as Giant and Krüppel (inhibitors) such that the gene is expressed only in the region where concentrations of the two activators are high and the concentrations of the two inhibitors are low. A reporter gene can be placed under the control of this module, and it can be shown to form a stripe in the same place in the embryo as the corresponding stripe of Eve. Answer the following question(s) based on these findings. -In the Eve regulatory modules, the binding sites for Giant and Krüppel are usually close to, or even overlapping with, those of Bicoid and Hunchback. This implies that Eve expression is regulated by … between the activators and regulators.

Consider the descriptions below for three different lncRNAs, and determine whether they function in cis (C) or in trans (T). Your answer would be a three-letter string composed of letters C and T only, e.g. CCT. ( ) The tsiX RNA is transcribed from the X-inactivation center in the X chromosome that will not be inactivated. It is antisense with respect to Xist, repressing its transcription and function. ( ) The ANRIL lncRNA is an antisense transcript in a gene cluster expressing inhibitors of cell-cycle proteins. It silences the entire cluster by recruiting heterochromatin proteins of the Polycomb group. ( ) The PTENP1 lncRNA is similar to an mRNA that encodes the protein PTEN, and contains many of the miRNA response elements present in PTEN mRNA; it therefore protects the PTEN mRNA from miRNA-mediated silencing by acting as a decoy.