METTL3 Modulates Ctsk+ Lineage Supporting Cranial Osteogenesis via Hedgehog.

N6-methyladenosine (m6A) modification, a eukaryotic messenger RNA modification catalyzed by methyltransferase-like 3 (METTL3), plays a pivotal role in stem cell fate determination. Calvarial bone development and maintenance are orchestrated by the cranial sutures. Cathepsin K (CTSK)-positive calvarial stem cells (CSCs) contribute to mice calvarial ossification. However, the role of m6A modification in regulating Ctsk+ lineage cells during calvarial development remains elusive. Here, we showed that METTL3 was colocalized with cranial nonosteoclastic Ctsk+ lineage cells, which were also associated with GLI1 expression. During neonatal development, depletion of Mettl3 in the Ctsk+ lineage cells delayed suture formation and decreased mineralization. During adulthood maintenance, loss of Mettl3 in the Ctsk+ lineage cells impaired calvarial bone formation, which was featured by the increased bone porosity, enhanced bone marrow cavity, and decreased number of osteocytes with the less-developed cellular outline. The analysis of methylated RNA immunoprecipitation sequencing and RNA sequencing data indicated that loss of METTL3 reduced Hedgehog (Hh) signaling pathway. Restoration of Hh signaling pathway by crossing Sufufl/+ alleles or by local administration of SAG21 partially rescued the abnormity. Our data indicate that METTL3 modulates Ctsk+ lineage cells supporting calvarial bone formation by regulating the Hh signaling pathway, providing new insights for clinical treatment of skull vault osseous diseases.

A Survey on Oral Health and Practice of Nepalese in Areas Affected by Earthquake in 2015.

Background Understanding post-earthquake oral health indicators is essential for developing oral health interventions of the victims. Presumably, due to a geographic difficulty, there has been no investigation to reveal the oral health status of individuals after the Gorkha earthquake in Nepal. Objective The main objective was to determine the oral health and practice of Nepalese affected by earthquake in April-May, 2015. Method The epidemiological cross sectional study was done at 5 different districts (Sindhupalchok, Dadhing, Bhaktapur, Kathmandu and Kavre) of Nepal from September till November, 2015. Altogether 500 subjects aged form 16 to 80 years of age living in the transitional shelters community were included in earthquake-affected areas. Different parameters were studied from past and present medical and dental problems, habits, oral hygiene habits. DMFT, gingival index, periodontal index were studied and correlation was studied among them. Result It shows that 98% of the participants had plaque and 96.4% of the participants had calculus. Mean decayed was 9, mean missing was 4 and mean filling was 1. 22.60% of the participants had score 0, 34.8% had score 1, 34% had score 2 and 8.60% had score 3 of mean gingivitis index. 10% of the participants showed score 0, 36% showed score 1, 35% showed score 2, 10.2% showed score 3 and 8.2% showed score 4 of mean periodontal index. Moreover, significant correlation was observed among DMFT index, gingival index and periodontal index (p<0.001). Conclusion The oral health care practice, oral hygiene habits, nutritional intake of the people have been affected in the earthquake affected areas. It showed high caries index, gingival index and periodontal index in earthquake affected people suggesting further efforts are needed for an oral health improvement. Data from this study may be used as basic information for oral health planning and future steps in oral health care preventive and therapeutic programs.