CD44 in Differentiated Embryonic Stem Cells: Surface Expression and Transcripts Encoding Multiple Variants

摘要

Expression of the surface-adhesion molecule CD44 was investigated during thein vitrodifferentiation of the embryonic stem (ES) cell line D3. By immunofluorescence analysis,totipotent, undifferentiated ES cells did not show surface expression of CD44, although twotranscripts of approximately 1.6 and 3.3 kb were detected on Northern blots. Following 1week of differentiation in either suspension or substrate-attached cultures, CD44 appearedon the surface of some D3 cells, and synthesis of an additional 4.5 kb mRNA species wasdetected on Northern blots. At this stage, at least three distinct transcripts encoding CD44variants were induced within the cultures, resulting from alternative splicing of additionalexons in the variable domains of CD44. From PCR analysis, they all appeared to contain thevariable exon v10, and two of them in addition contained v6. Taken together, these resultssuggest that CD44 may play a role in cell migration and adhesion in the early developmentof the mouse embryo.