Expression and alternative splicing of the neural cell adhesion molecule NCAM in human granulosa cells during luteinization

Freshly aspirated human granulosa cells from pre-ovulatory
follicles and granulosa cells luteinized in culture possess the
neural cell adhesion molecule (NCAM) of approximate molecular mass
of 140,000 and NCAM mRNA as confirmed by S1-nuclease protection
assays and RT-PCR. Moreover, in the process of luteinization the
NCAM isoform pattern is modified. Isoforms containing an insert of
10 amino acids (termed VASE) in the extracellular domain of NCAM
were supplemented by alternatively spliced isoforms without this
insert. NCAM immunoreactivity, at light and electron microscope
levels, was associated with the cell membrane of most granulosa
cells which formed clusters. During time in culture an increasing
subpopulation of granulosa cells, devoid of NCAM immunoreactivity,
spread out and formed monolayers. This differential expression and
the alternative splicing of NCAM during luteinization of granulosa
cells raise the possibility that NCAM could be involved in
folliculogenesis and the formation of the corpus luteum in the
human.