Expression of galectin-7 during epithelial development coincides with the onset of stratification.
Galectin-7 is a 14 KDa member of the galectin family that we have cloned from human, rat and mouse. Our previous studies have shown that in the adult, galectin-7 is expressed in all cell layers of epidermis and of other stratified epithelia such asthe cornea and the lining of the oesophagus. This suggested that galectin-7 expression might be induced at a particular stage in the embryonic development of stratified epithelia. In the present study we have investigated this hypothesis by in situ hybridization of galectin-7 mRNA in mouse embryos. Starting from E13.5, weak expression of galectin-7 was detected in bilayered ectoderm, and stronger expression was found in areas of embryonic epidermis where stratification was more advanced. Galectin-7 expression was maintained in all living layers after epidermal development was completed. Galectin-7 was also strongly and specifically expressed in stratified regions of ectodermally-derived non-epidermal epithelia such as the lining of the buccal cavity, the oesophagus and the ano-rectal region. In contrast, no expression of galectin-7 was found in epithelia derived from endoderm, such as lining of the intestine, kidney and lung. Our results demonstrate that galectin-7 is expressed in all stratified epithelia examined so far, and that the onset of its expression coincides with the first visible signs of stratification. These results establish galectin-7 as the first region-independent marker of epithelial stratification.
Unité INSERM 257, ICGM, Paris, France.
P M
PM
Timmons
C
C
Colnot
I
I
Cail
F
F
Poirier
T
T
Magnaldo
D000818:Animals; D005314:Embryonic and Fetal Development / Q000235:genetics*; D004848:Epithelium / Q000196:embryology / Q000502:physiology; D037161:Galectins; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D037102:Lectins / Q000235:genetics*; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats
D037161:Galectins; C092525:LGALS7 protein, human; D037102:Lectins; C490487:Lgals7 protein, mouse; C490488:Lgals7 protein, rat; D012333:RNA, Messenger