Master Transcription Regulators

Many complex cellular processes are controlled by a few key transcription factors, known as master transcription regulators. These master regulators promote or inhibit the transcription of groups of genes, such as those required for cell differentiation. 

These important proteins can function either directly or indirectly to regulate gene expression.

Master transcription regulators can bind directly to cis-regulatory sequences to control the transcription of multiple genes involved in related cellular responses. 

MyoD is a master transcriptional regulator required for muscle cell differentiation. It binds to cis-regulatory sequences of hundreds of genes involved in muscle development, including the myosin heavy chain, a motor protein found in muscle, and desmin, a muscle-specific intermediate filament.

Master transcription regulators can also act indirectly by binding to cis-regulatory sequences that control the production of other transcription factors. 

MyoD binds to regulatory sequences that induce the expression of other transcription factors, such as myocyte-specific enhancer factor 2, that regulates additional genes needed for the development and repair of muscle tissue.

Master regulators often work together to promote cell differentiation. The master regulators Oct4 and Sox2 work together to regulate the expression of Zfp206. This transcription factor must be highly expressed in the embryonic stem cells of mice and humans to trigger cell differentiation. 

Similarly, together, PPARγ and C/EBPα trigger adipocyte, or fat cell development by binding to cis-regulatory sites for adipocyte-specific proteins. Additionally, PPARγ and C/EBPα each bind to a transcription regulatory site for the other creating a positive feedback loop to increase transcription during differentiation further.