Analysis of expression patterns of IGF-1, caspase-3 and HSP-70 in developing human tooth germs.
OBJECTIVE
To analyze expression patterns of IGF-1, caspase-3 and HSP-70 in human incisor and canine tooth germs during the late bud, cap and bell stages of odontogenesis.


METHODS
Head areas or parts of jaw containing teeth from 10 human fetuses aged between 9th and 20th developmental weeks were immunohistochemically analyzed using IGF-1, active caspase-3 and HSP-70 markers. Semi-quantitative analysis of each marker's expression pattern was also performed.


RESULTS
During the analyzed period, IGF-1 and HSP-70 were mostly expressed in enamel organ. As development progressed, expression of IGF-1 and HSP-70 became more confined to differentiating tissues in the future cusp tip area, as well as in highly proliferating cervical loops. Few apoptotic bodies highly positive to active caspase-3 were observed in enamel organ and dental papilla from the cap stage onward. However, both enamel epithelia moderately expressed active caspase-3 throughout the investigated period.


CONCLUSIONS
Expression patterns of IGF-1, active caspase-3 and HSP-70 imply importance of these factors for early human tooth development. IGF-1 and HSP-70 have versatile functions in control of proliferation, differentiation and anti-apoptotic protection of epithelial parts of human enamel organ. Active caspase-3 is partially involved in formation and apoptotic removal of primary enamel knot, although present findings might reflect its ability to perform other non-death functions such as differentiation of hard dental tissues secreting cells and guidance of ingrowth of proliferating cervical loops.
Study Programme of Dental Medicine, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia. Electronic address: dkero@mefst.hr.
Darko
D
Kero
Study Programme of Dental Medicine, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
Danijela
D
Kalibovic Govorko
Study Programme of Dental Medicine, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
Ivana
I
Medvedec Mikic
Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
Katarina
K
Vukojevic
Study Programme of Dental Medicine, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
Livia
L
Cigic
Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Soltanska 2, 21000 Split, Croatia.
Mirna
M
Saraga-Babic
D053148:Caspase 3 / Q000096:biosynthesis*; D002454:Cell Differentiation; D003481:Cuspid / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D003743:Dental Enamel / Q000378:metabolism; D003771:Dental Papilla / Q000166:cytology / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D004658:Enamel Organ / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D005333:Fetus; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D007180:Incisor / Q000196:embryology / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis*; D009805:Odontogenesis; D014083:Tooth Germ / Q000166:cytology / Q000196:embryology / Q000378:metabolism*
D018840:HSP70 Heat-Shock Proteins; D007334:Insulin-Like Growth Factor I; D053148:Caspase 3
Caspase-3; HSP-70; Human tooth development; IGF-1