High impact information on LMX1B

• Ectopic expression of Lmx1 in the ventral mesenchyme is sufficient to generate double-dorsal limbs [1].
• C-Lmx1 expression is regulated by the overlying ectoderm where Wnt7a messenger RNA is localized [2].
• Furthermore, the expression of Wnt7a, Lmx1 and En1, genes involved in limb D-V patterning, was found to be abnormal in mutant limb buds [3].
• Thereafter, the formation of the otic vesicle was progressively autonomous, and by the stage of 10 somites the otic ectoderm developed into otic vesicles and expressed lmx1 in foreign environments [4].
• Removal of the ventral aspect of the neural tube (including the notochord) had opposite effects, expression of lmx1 increased, and its domain expanded [4].

Biological context of LMX1B

• The question arises how En-1 and Lmx1, whose role in dorsoventral limb patterning has been well established, can affect skin morphogenesis, which occurs 8 to 12 days later [5].

Anatomical context of LMX1B

• Misexpression of C-Lmx1 during limb outgrowth causes ventral to dorsal transformations of limb mesoderm [2].
• Ablation of the dorsal neural tube resulted in a reduced expression of lmx1, which was more dramatic during early placode and preplacode stages (5-7 somites) [4].
• In 2- to 7-day chick embryos, we find that genes of the LIM homeobox family are expressed differentially among cranial motor nuclei [6].
• At otic cup stages, lmx1 was downregulated in ventral and medial aspects of the otic epithelium facing the neural tube [4].
• Differential expression of LIM homeobox genes among motor neuron subpopulations in the developing chick brain stem [6].

Other interactions of LMX1B

• We have isolated a novel chick transcript, ALC (adjacent to LMX1 in chick) [7].
• A secreted factor Wnt7a and a homeobox protein Lmx1 are involved in the dorsal patterning of the limb, whereas a homeobox protein Engrailed 1 (En1) is involved in the dorsal-ventral patterning as well as AER formation [8].

References