Putative “Stemness” Gene Jam-B Is Not Required for Maintenance of Stem Cell State in Embryonic, Neural, or Hematopoietic Stem Cells

Abstract

Many genes have been identified that are specifically expressed in multiple types of stem cells in their undifferentiated state. It is generally assumed that at least some of these putative “stemness” genes are involved in maintaining properties that are common to all stem cells. We compared gene expression profiles between undifferentiated and differentiated embryonic stem cells (ESCs) using DNA microarrays. We identified several genes with much greater signal in undifferentiated ESCs than in their differentiated derivatives, among them the putative stemness gene encoding junctional adhesion molecule B (Jam-B gene). However, in spite of the specific expression in undifferentiated ESCs, Jam-B mutant ESCs had normal morphology and pluripotency. Furthermore, Jam-B homozygous mutant mice are fertile and have no overt developmental defects. Moreover, we found that neural and hematopoietic stem cells recovered from Jam-B mutant mice are not impaired in their ability to self-renew and differentiate. These results demonstrate that Jam-B is dispensable for normal mouse development and stem cell identity in embryonic, neural, and hematopoietic stem cells.

We are grateful to Jun Nomura and Konosuke Mitani for their insightful ideas and encouragement.

This work was supported in part by the Ministry of Education, Science, Sports, and Culture, in particular by a Ministry Grant to Saitama Medical University Research Center for Genomic Medicine. This work was also performed as part of the Rational Evolutionary Design of Advanced Biomolecules (REDS) Project, Saitama Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence, supported by the Japan Science and Technology Agency, Japan.