Grem2 Deficiency Disrupts Msc Homeostasis Leading To Tooth Agenesis

Nonsyndromic tooth agenesis/hypodontia represents the most prevalent human dental developmental disorder. While GREMLIN 2 (GREM2) mutations are clinically linked to isolated tooth agenesis, microdontia, and taurodontism, their pathogenic mechanisms remain elusive, This study aims to 1) characterize Grem2′s spatiotemporal expression pattern during odontogenesis, and 2) elucidate its mechanistic role in MSC homeostasis regulation underlying dental malformations. Grem2 expression were spatially mapped with scRNA-seq, RNAScope ISH, and immunofluorescence. Grem2-KO mice were generated using CRISPR-Cas9 method. Molar and incisor agenesis phenotype was evaluated by micro-CT, H&E, and IHC staining. MSC function were assayed through EdU incorporation and injury response. Downstream analyses were performed by Bulk RNA-seq and in-vitro cell culture validation. Grem2+ cells constitute a unique MSC subpopulation localized to dental follicle (incisors) and apical periodontal regions (molars), co-expressing with Gli1+cell and label-retaining cell, indicating it may regulate MSC homeostasis. Grem2-KO mice exhibited tooth agenesis with taurodontism molars and needle-like incisors. The incisors showed narrowed pulp chamber and apical-lingual region close failure. Grem2 deficiency slowed the incisor eruption rate and impaired the MSC proliferation and injury-response ability. Mechanically, Grem2 may regulate MSC homeostasis through Ogn-Shh axis. As the first demonstration of Grem2′s essential role in dental MSC homeostasis regulation, this study identifies Grem2 as novel MSC regulator and uncovered the pathogenic mechanism underlying GREM2-associated malformations, which may offer therapeutic targets for congenital tooth agenesis management.