Neurohypophysial dysmorphogenesis in mice lacking the homeobox gene Uncx4.1.

A number of transcription factors have been implicated in the development of the hypothalamo-neurohypophysial system (HNS). Null mutations for these factors caused severe defects in proliferation, migration and survival during early embryogenesis. While they have informed about early events of HNS developments no insights in mechanisms of late development and maturation of this major peptidergic system have been obtained as yet.

CNS expression pattern of Lmx1b and coexpression with ptx genes suggest functional cooperativity in the development of forebrain motor control systems.

In the central nervous system, acquisition of regional specification is an important developmental process. The regional specification is reflected by restricted and overlapping expression of homeobox genes, which are regulators of this event. Here, we detail the expression pattern of Lmx1b during late embryonic brain development and show that this gene is expressed in multiple regions and diverse sets of neurons.

Survey for paired-like homeodomain gene expression in the hypothalamus: restricted expression patterns of Rx, Alx4 and goosecoid.

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.

The homeobox genes Lhx7 and Gbx1 are expressed in the basal forebrain cholinergic system.

The specific combination of homeobox genes is proposed to be decisive in the terminal differentiation of neuronal systems. In order to identify combined expression of homeobox genes in the ventral forebrain, a reverse transcriptase-polymerase chain reaction strategy using degenerated primers was employed. We identified, amongst others, Lhx7 and Gbx1, displaying a marked overlapping expression in septal and pallidal areas.

A second independent pathway for development of mesencephalic dopaminergic neurons requires Lmx1b.

We identified the LIM homeodomain transcription factor Lmx1b in the mesencephalic dopamine (mesDA) systems of embryos and adults. Analysis of spatiotemporal expression in Lmx1b null mutants and wild-type mice implicated a cascade involving Lmx1b in the early development of mesDA neurons. Although disruption of this cascade did not block induction of tyrosine hydroxylase (TH), a key enzyme in DA synthesis, or Nurr1, a nuclear hormone receptor, Lmx1b knockout mice failed to induce the mesDA-specific homeodomain gene Ptx3 in TH-positive neurons.