D. Osterloh et al., CHARACTERIZATION AND DEVELOPMENTALLY-REGULATED EXPRESSION OF 4 ANNEXINS IN THE KILLIFISH MEDAKA, DNA and cell biology, 17(10), 1998, pp. 835-847
Annexins are Ca2+-regulated membrane binding proteins implicated in a
wide range of membrane-related and signal transduction events, includi
ng the endocytosis of membrane receptors and Ca2+-regulated as well as
constitutive secretion, To date, 10 unique members of this multigene
family have been identified in a variety of cell types and tissues of
higher vertebrates, with different members showing distinct tissue dis
tributions in the adult organisms. To establish whether annexins also
function in embryonic development, we analyzed the expression pattern
during vertebrate morphogenesis using the medaka fish Oryzias latipes
as a model system, From a larval medaka cDNA library, we isolated four
types of clones, which were shown by sequence analysis to encode four
different annexins (herein referred to as max 1-4). A comparison with
known annexin sequences in the databases revealed that two medaka ann
exins (max 1 and 2) are highly similar in sequence to mammalian annexi
ns V and IV, respectively, whereas the other two medaka annexins (max
3 and 4) are probably novel members of the family most closely related
to mammalian annexins I and XI, Using whole-mount RNA in situ hybridi
zation, we showed that the expression of the different medaka annexins
during embryogenesis was strictly regulated at both the spatial and t
he temporal level, High levels of max 1, 2, and 3 transcripts were pre
sent in the developing stomach, gut, liver, air-bladder, and rectum du
ring somitogenesis, thus identifying the digestive tract as the prime
region of annexin expression, Interestingly, two structures playing cr
ucial roles in neuronal patterning showed a distinct expression of ann
exins, The mesendoderm of the anterior prechordal plate of neurula-sta
ge embryos was a site of max 4 transcription, and the floor plate of s
omitogenesis-stage embryos showed expression of max 2 and 3 to differi
ng rostrocaudal extends along the brain and spinal cord. These results
suggest specific functions of different annexins during vertebrate mo
rphogenesis.