Question

Enhancers are said to be cis-acting. What is meant by cis-acting, and what are enhancers?

Enhancers are said to be cis-acting. What is meant by cis-acting, and what are enhancers? Essay answers are limited to about 500 words (3800 characters maximum, including spaces). 3800 Character(s) remaining

Answer 1

Transcription initiation is the most common target of regulatory mechanisms. The mechanisms include cis acting DNA binding elements (enhancers) that regulate gene expression. These are including enhancers and promoters associated with TATA box, initiators, response elements these cis-acting regulatory elements binds with transcription factors (trans-acting regulatory elements) to promote transcription. Normally trans acting elements are going to promote transcription by binding to TATA box.

Enhancers: These are “gene regulatory elements” and going to interact with protein molecules profoundly bind to the promoter DNA sequences. These are going to act on either upstream, downstream, or within gene

cis-acting regulatory sequences: These are going to control transcription initiation on the same chromosome but has no influence on other chromosomes

Barrier elements differ from insulators and barrier elements specifically enable division of chromosomes into finally as independent free domains. Barrier elements potentially avoid action of enhancers on promoters that situated next to adjacent domains. These independent domains act transcriptional activators to activate gene expression by binding to specific DNA segment.

Insulators called as boundary elements that regulate the eukaryotic transcription in the DNA sequences that usually function to limit or to isolate the activity of an enhancer. These boundary elements often enable in providing a physical barrier in order to keep the enhancers from enhancing a wrong gene. These are having a crucial regulation on mRNA processing followed by RNA stability and RNA silencing. For example in Drosophila species, pair rule and gap gene transcription associated with Sxl –lethal that predominantly affects splicing by binding to the pre-mRNA whereas tran (transformer) of pre mRNA regulated at splicing region.   

For example:

Drosophila embryogenesis- Gap genes- The Gap genes, which involve in the segmental embryogenesis of fruit fly include, transcriptional factors such as Giant, Bicoid, Hunchback associated with eve (even-skipped as per pair-rule). Expression of eve gene greatly depends on the 3 these “cis-acting enhancers” associated with stripe 2. Usually the anterior-posterior incline of Bicoid associate with Hunchback are predominantly important either to inhibit or express gap genes such as eve genes. This Bicoid + Hunch back enable anterior –posterior axis of fruit fly from embryo by stripe 2 enhancement for further expression.