text: Sox9 neural crest determinant gene controls patterning and closure of the posterior frontal cranial suture.
  Cranial suture development involves a complex interaction of genes and tissues derived from neural crest cells (NCC) and paraxial mesoderm. In mice, the posterior frontal (PF) suture closes during the first month of life while other sutures remain patent throughout the life of the animal. Given the unique NCC origin of PF suture complex (analogous to metopic suture in humans), we performed quantitative real-time PCR and immunohistochemistry to study the expression pattern of the NCC determinant gene Sox9 and select markers of extracellular matrix. Our results indicated a unique up-regulated expression of Sox9, a regulator of chondrogenesis, during initiation of PF suture closure, along with the expression of specific cartilage markers (Type II Collagen and Type X Collagen), as well as cartilage tissue formation in the PF suture. This process was followed by expression of bone markers (Type I Collagen and Osteocalcin), suggesting endochondral ossification. Moreover, we studied the effect of haploinsufficiency of the NCC determinant gene Sox9 in the NCC derived PF suture complex. A decrease in dosage of Sox9 by haploinsufficiency in NCC-derived tissues resulted in delayed PF suture closure. These results demonstrate a unique development of the PF suture complex and the role of Sox9 as an important contributor to timely and proper closure of the PF suture through endochondral ossification.
  
entities: ['posterior frontal cranial suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T1
entities: ['Cranial suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T2
entities: ['neural crest cells']
entities: Cell
entities: PMID-15882577_T3
entities: ['NCC']
entities: Cell
entities: PMID-15882577_T4
entities: ['paraxial mesoderm']
entities: Multi-tissue_structure
entities: PMID-15882577_T5
entities: ['tissues']
entities: Tissue
entities: PMID-15882577_T6
entities: ['posterior frontal (PF) suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T7
entities: ['sutures']
entities: Multi-tissue_structure
entities: PMID-15882577_T8
entities: ['NCC']
entities: Cell
entities: PMID-15882577_T9
entities: ['PF suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T10
entities: ['metopic suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T11
entities: ['NCC']
entities: Cell
entities: PMID-15882577_T12
entities: ['extracellular matrix']
entities: Cellular_component
entities: PMID-15882577_T13
entities: ['PF suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T14
entities: ['cartilage']
entities: Tissue
entities: PMID-15882577_T15
entities: ['cartilage tissue']
entities: Tissue
entities: PMID-15882577_T16
entities: ['PF suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T17
entities: ['NCC']
entities: Cell
entities: PMID-15882577_T18
entities: ['NCC']
entities: Cell
entities: PMID-15882577_T19
entities: ['PF suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T20
entities: ['NCC-derived tissues']
entities: Tissue
entities: PMID-15882577_T22
entities: ['PF suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T23
entities: ['PF suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T24
entities: ['PF suture']
entities: Multi-tissue_structure
entities: PMID-15882577_T25
entities: ['bone']
entities: Tissue
entities: PMID-15882577_T21
entities: ['neural crest']
entities: Tissue
entities: PMID-15882577_T26