Autophagy appears during the development of the mouse lower first molar.
Odontogenesis consists of a series of consecutive tooth morphogenesis stages, in which apoptosis is involved to eliminate the unnecessary cells. Autophagy, a lysosome or endosome-mediated self-degradation process, is indicated to participate in embryogenesis and tissue morphogenesis associated with apoptosis. This study hypothesized that autophagy may be involved and associated with apoptosis in odontogenesis. The transcripts of autophagy-related genes (Atg5, Atg7, and Atg12) were positively detected in tooth germs at embryonic day (E) 14.5 and postnatal day (P) 5.5 by quantitative real-time PCR. The protein expression of Atg5-Atg12 conjugate and lipidation of LC3 (microtubule-associated protein 1 light chain 3, autophagic marker) were revealed in the developing tooth germs by western blot. Meanwhile, LC3 was immunolocalized in the enamel organ and dental papilla at embryonic stages (E13.5-E18.5), especially stage E14.5 cervical loop and the PEK that facing the mesenchyme. At postnatal stages (P1.5-P15.5), besides the dental epithelium cells, LC3 was detected in the differentiating and differentiated odontoblasts, dental follicle cells, and Hertwig's epithelium root sheath cells. Moreover, double-immunofluorescence analysis revealed the partial colocalization of LC3 and TUNEL signal in the E14.5 PEK that facing the mesenchyme, the E16.5 stratum intermedium and outer enamel epithelium, the P5.5 stratum intermedium and stellate reticulum. Nevertheless, LC3 was also found in non-apoptotic cells. Furthermore, the transmission electron microscopic images revealed the presence of autophagy, as well as the partial colocalization of autophagic vacuoles and apoptotic nuclei during tooth development. Our findings imply the developmental appearance of autophagy and its partial colocalization with apoptosis during odontogenesis.
The State Key Laboratory Breeding Base of Basic Science of Stomatology-Hubei-MOST, Key Laboratory of Oral Biomedicine, Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079, China.
Jing-wen
JW
Yang
Ling-xin
LX
Zhu
Guo-hua
GH
Yuan
Yang-xi
YX
Chen
Li
L
Zhang
Lu
L
Zhang
Zhi
Z
Chen
D000818:Animals; D017209:Apoptosis; D001343:Autophagy / Q000235:genetics; D000071192:Autophagy-Related Protein 12; D000071187:Autophagy-Related Protein 5; D000071193:Autophagy-Related Protein 7; D015153:Blotting, Western; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D051379:Mice; D008813:Mice, Inbred ICR; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D008963:Molar / Q000196:embryology* / Q000378:metabolism / Q000648:ultrastructure; D009805:Odontogenesis; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D014083:Tooth Germ / Q000378:metabolism / Q000648:ultrastructure
C491971:Atg12 protein, mouse; C495773:Atg5 protein, mouse; C502661:Atg7 protein, mouse; D000071192:Autophagy-Related Protein 12; D000071187:Autophagy-Related Protein 5; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; D011506:Proteins; D012333:RNA, Messenger; D000071193:Autophagy-Related Protein 7