Question

Compare and contrast neurotransmitter receptor-mediated effects on gene transcription with steroid receptor-mediated effects on gene transcription

Answer 1

Both of the receptors are associated with a target cell and regulate the gene expression by inhibiting or stimulating it.

Neurotransmitters are specialised chemical signals which are secreted from the nerve terminals. They are secreted at the chemical synapse fromwhere they are essentially picked p by the post synaptic cell. Now, neurotransmitters such as acetylcholine receptors are ligand gated ion channels which are distributed in the brain. Now, these subunits and the enzyme involved in the synthesis of acetylcholine are expressed early. The activation of these type of receptors enhance early expression of genes prior to neuronal development. They mediate both excitatory and inhibtory responses.

Steroid receptors are a subset of proteins which are a part of the nuclear receptor superfamily. They include mineralocorticoid receptor, ER, PR etc. The coactivators which are present in the steroid hormone receptor are involved in the enhancement of transcriptional signal of the receptors following ligand binding. They enhance or repress gene transcription by forming homodimers which interact with specific DNA sequences in the promoter of the target genes. For example, steroidal receptors mediate the negative and positive feedback of gonadal steroids. Estradiol acts through nuclear estrogen receptors that regulate gene transcription within the target cell. They stimulate gene expression by removing an inhibitory transcription factor, facilitating activation of promoter, inhibit gene expression by removing a stimulatory transcription factor.