Mab21l2 Gene Cloning And Preliminary Function Study

There are huge number of various cell in nervous system, making the latter the most important and complex organ of animal. The genes expressed in nervous system is much more than in other organs. The development of the nervous system is tightly and precisely controlled. In the early stage of its development, once induced by the morphogen, transcription factors such as SHH, WNT and BMP, are specifically expressed in neuronal cells to trigger the downstream effects, and determine the cell fate finally. TGF- β family is one type of morphogen. Once binding with the receptors, they transfer the signal into the nucleus through Smads, and regulated the transcription of target genes.Here we describe the identification and characterization of a novel protein, designated MAB21L2 (AF370007). Full-length MAB21L2 cDNA was isolated from human fetal brain cDNA library. MAB21L2 is comprised of 359 amino acids which are encoded by a 1127 bp open reading frame. MAB21L2 shows 55% identity and 73% positives with MAB-21 of C.elegans. MAB21L2 is highly conserved in evolution, but does not contain any known functional domain. It is identified as a ubiquitously expressed protein by Northern blotting analysis. Immunocytochemistry and confocal microscopy experiment shows that MAB21L2 is distributed both in the cell nucleus and cytoplasm. MAB21L2 selectively interacts with Smad4 but not with Smad1 and Smad3 in the yeast two-hybrid system and this interaction was confirmed by pull-down assay and co-immunoprecipitation. The N-terminal 48 residues and C terminal 66 residues are responsible for the interaction. Our findings suggest a new mechanism by which MAB21L2 functions in nervous system development.