Expression patterns of the homeo box-containing genes En-1 and En-2 and the proto-oncogene int-1 diverge during mouse development.

Abstract

We have compared the expression of the murine genes En-l,En-2, and int-1 during development by in situ hybridization. Expression of all three genes was first detected at 8.0 days in overlapping bands of the anterior neural folds. By 12.0 days the expression patterns diverged. En-1 and En-2 were expressed in a similar ring of cells in the central nervous system (CNS) at the midbrain/hindbrain junction. En-1 was also expressed de novo in two lateral stripes extending the length of the hindbrain and spinal cord, in the developing vertebral column, in two lateral stripes of dermatome-derived cells, and in the tail and limb buds. By 12.0 days int-1 expression showed little overlap with the En genes and could not be detected at later stages. At 15.5 days En gene expression was primarily limited to the midbrain/hindbrain in overlapping but nonidentical sets of differentiated cells. In the adult, En-1 and En-2 marked the same sets of cells in the pons, but En-2 alone was detected in the granular layer of the cerebellum. The results are consistent with int-1 and the En genes playing a role early in development in defining spatial domains in the CNS. Later in development the En genes may have an additional function in neurogenesis. En-1 expression in the developing pericordal tube suggests that it may also be involved in vertebral assembly.

Neonatal serotonin depletion alters behavioral responses to spatial change and novelty

“…It is interesting in this context to note that a defective serotonergic innervation is also compatible with alterations of brainstem segmentation genes such as engrailed or Hox 2, which have been implicated in autism (Polleux and Lauder, 2004;Bartlett et al, 2005;Benayed et al, 2005). Serotonergic projection neurons develop in the brainstem areas under control of these segmentation genes (Davis and Joyner, 1988;Gavalas et al, 2003). Yet, serotonergic afferents only innervate cortex just before birth and thus begin to exert their effects on cortical maturation predominantly after birth in both rodent and human (Lidov and Molliver, 1982;Dori et al, 1996;Connell et al, 2004).…”

Expression patterns of the murine LIM class homeobox gene lim1 in the developing brain and excretory system

“…The largest class of homeobox genes, the Hox genes, are expressed in a region posterior to the midbrain where they are thought to confer regional identity on specific fields of cells (review in Deschamps and Meijlink, 1992;McGinnis and Krumlauf, 1992). Likewise, en-1 and en-2 are not expressed anterior of the midbrain (Davis and Joyner, 1988), and are known to be involved in midbrain and hindbrain development (Joyner et al, 1991). Genes of the Pax family, on the other hand, are expressed along the entire longitudinal axis of the neural tube (for review, see Deutsch and Gruss, 1991).…”

The mouse Engrailed genes: A window into autism

“…A null mutation of En1 results in the absence of most of the cerebellum and midbrain, and in lethality shortly after birth [66]. En2 expression is also found at the presumptive midbrain-hindbrain region but initiates later, at the 5 somite stage [25,26]. Unlike En1, null alleles of Engrailed-2 have only a subtle neurological phenotype.…”