Stam2 expression pattern during embryo development.

STAM2 is a tyrosine-phosphorylated protein suggested to be involved in cargo selection during endocytic pathway, regulation of exocytosis and intracellular signaling. Gene trap method was used to create via insertional mutagenesis a mutant mouse line with integration of promoterless βgeo (lacZ-neomycin phosphotransferase fusion) gene in the second intron of Stam2 gene, enabling analysis of its in vivo expression and function. The inserted β-galactosidase (lacZ) reporter gene was used to reveal Stam2 expression during development. Stam2 in situ RNA hybridization and immunostaining confirmed the observed β-galactosidase activity reflecting high Stam2 expression. The homozygous mutant mice showed no overt phenotypic alterations. Stam2 expression was detected after E9.5 in the gut, notochord, neural tube and heart. In the nervous system it was located in the floor, roof and basal plates of the developing neural tube, and in the developing cortex, hippocampus and olfactory bulbs. Toward the end of gestation, Stam2 expression appeared in the testis and ovary, lungs, nasal cavity epithelium, kidneys, urogenital sinus, intestine, pancreas, pituitary and adrenal glands, muscles, brown adipose tissue, skin and epithelium of the tongue and oral cavity.