Neurons and a Subset of Interstitial Cells of Cajal in the Enteric Nervous System Highly Express Stam2 Gene

Abstract

Signal transducing adaptor molecule 2 (STAM2) is a phosphotyrosine protein, which is a member of the endosomal sorting complex required for transport (ESCRT-0) and is involved in the sorting process of the mono-ubiquitinated endosomal cargo for degradation in the lysosome. Analysis of gene trap mice carrying lacZ in frame with Stam2 revealed beta-galactosidase activity in the enteric nervous system (both in the myenteric and submucosal plexus) throughout the digestive tract. STAM2 immunostaining confirmed that the observed beta-galactosidase activity coincided with high Stam2 expression. To identify cell types with high Stam2 expression, STAM2 immunostaining was colocalized with the neuronal markers microtubule-associated protein 2 and protein gene product 9.5 and with c-kit as a marker for interstitial cells of Cajal (ICCs). STAM2 and c-kit positive cells comprised a subset of ICCs in the enteric nervous system. Qualitative and quantitative analysis of the morphology of the enteric nervous system in the homozygous mice carrying gene trap insertion in the Stam2 gene did not reveal phenotype changes; therefore, STAM2 function in the digestive tube remains elusive.