ABSTRACT
Homeobox genes are important regulators of cellular identity. Several homeobox genes are known to be specifically expressed in subsets of neurons in the forebrain, exclusively, or in distinct combinations. In this study, we explored the expression of homeobox genes in the forebrain of the adult rat by a degenerate polymerase chain reaction cloning strategy. We identified the expression of 12 homeobox genes, several of which display a remarkable restricted expression pattern in the adult brain. We demonstrated the expression of goosecoid in a very small set of neurons in the hypothalamus. By using Otp as a marker, these goosecoid-positive cells were found to constitute a small area just beside the paraventricular nucleus. Furthermore, we found expression of Rx in the pineal gland, along with Alx4. Rx was additionally found in the posterior pituitary and in cells aligning the bottom of the third ventricle. These findings form a starting point to reveal functions of the described homeobox genes in the forebrain.
Subject(s)
DNA-Binding Proteins , Eye Proteins , Gene Expression Regulation, Developmental/physiology , Homeodomain Proteins/genetics , Hypothalamus/embryology , Hypothalamus/physiology , Repressor Proteins , Transcription Factors , Age Factors , Amino Acid Sequence , Animals , Cloning, Molecular , Goosecoid Protein , Mice , Molecular Sequence Data , Proteins/genetics , Rats , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The transcription factors that confer high level expression and regulate the genes encoding neurohypophysial hormones are largely unknown. A number of different approaches have been taken to identify these factors and to elucidate molecular mechanisms of physiological gene regulation. In this chapter two transcription factor families are considered: homeodomain proteins and nuclear receptors. Their identification in the hypothalamus and actions on the OT gene are addressed here.