High impact information on MNR2

• Specification of motor neuron identity by the MNR2 homeodomain protein [1].
• Recent studies have taken advantage of complementary gain and loss-of-function studies in the chick and mouse to clarify the in vivo roles of transforming growth factor beta signaling, basic helix-loop-helix and homeodomain transcription factors in dorsal interneuron development [2].
• In the developing spinal cord, motor neurons acquire columnar subtype identities that can be recognized by distinct profiles of homeodomain transcription factor expression [3].
• Experiments in the chick suggest that the dorsalizing activity of Wnt-7a in the mesenchyme is mediated through the regulation of the LIM-homeodomain transcription factor Lmx-1 [4].
• LIM homeodomain proteins Islet-1 and Lim-3 expression and their role in nervous tissue and endocrine glands have been reported; however, nothing is known concerning Islet-1 and Lim-3 expression in the developing pineal gland of the chick embryo [5].

Biological context of MNR2

• The ectopic expression of MNR2 in neural cells initiates a program of somatic motor neuron differentiation characterized by the expression of homeodomain proteins, by neurotransmitter phenotype, and by axonal trajectory [1].
• Here we report an amphioxus homologue of these genes and show that it diverged before the gene duplication yielding HB9 and MNR2 [6].
• The genomic organization and protein sequence of the human gene are highly conserved with respect to those of its Xenopus and mouse counterparts: all three genes consist of three exons, with conserved exon-intron boundaries; the sequence of the homeodomain is 100% conserved in most vertebrates [7].
• Islet-1 (Isl-1) is a LIM domain/homeodomain-type transcription regulator that has been originally identified as an insulin gene enhancer binding protein [8].
• RESULTS: Subtractive hybridization identified transcripts encoding Hop, a short, atypical homeodomain-containing protein that had previously been shown to be an important regulator of gene expression in the heart and lung [9].

Anatomical context of MNR2

• LIM homeodomain proteins Islet-1 and Lim-3 expressions in the developing pineal gland of chick embryo by immunohistochemistry [5].
• Our data is consistent with a role for islet-1 in differentiating inner ear neurons and sensory epithelia cells, perhaps in the specification of cellular subtypes in conjunction with other LIM/homeodomain proteins [10].
• Melatoninergic differentiation of retinal photoreceptors: activation of the chicken hydroxyindole-O-methyltransferase promoter requires a homeodomain-binding element that interacts with Otx2 [11].
• Here we show that during specification of the elbow joint in the chick limb bud, the homeodomain transcription factors Dlx5 and Dlx6 are highly expressed by a discrete group of cells that encompass the prospective elbow joint [12].
• Prox1 is a divergent homeodomain protein important for the development of the lens, retina, liver, pancreas, and lymphatic vasculature [13].

Associations of MNR2 with chemical compounds

• Transcriptional activation by the zinc-finger homeodomain protein delta EF1 in estrogen signaling cascades [14].

Other interactions of MNR2

• The amino acid sequences in homeodomain and its downstream encoded by human and chick Gbx1 cDNA were almost the same, but those upstream of the homeodomain were rather different [15].
• This upregulation does not require protein synthesis, suggesting a direct effect of the homeodomain on MAP1B transcription [16].
• AKR (Avian Knotted-Related) was the first example of a vertebrate homeodomain protein with a highly divergent Ile residue at position 50 of the DNA-recognition helix [17].

References