Early in vivo and in vitro effects of amelogenin gene splice products on pulp cells

Abstract

Recombinant amelogenin gene splice products A+4 and A-4, implanted in the pulp, induce the recruitment, proliferation, and differentiation of reparative cells. Our aim was to investigate the precocious events occurring in the pulp 1 d and 3 d after implantation of agarose beads alone or loaded with A+4 or A-4. Proliferation and cell recruitment towards an odonto/osteogenic phenotype were visualized by detection of the proliferation cell nuclear antigen (PCNA) and RP59. After implantation of beads alone or loaded with A+4, at day 3, pulp cells were moderately immunopositive for osteopontin (OP), whereas labeling was strongly positive upon treatment with A-4. Dentin sialoprotein (DSP) labeling was not detectable. Parallel in vitro studies were carried out on odontoblastic and mesenchymal progenitor cells in order to evaluate the effect of the amelogenin peptides on the expression of a series of marker genes involved in the odontoblastic/osteogenic/chondrogenic differentiation pathways. Altogether, our results suggest that the 'signaling' effects of the amelogenin peptides A+4 and A-4 may differ according to the type of target cells, their stage of differentiation, the time of treatment, and the type of amelogenin peptide (A+4 or A-4).

Amelogenin in cranio‐facial development: the tooth as a model to study the role of amelogenin during embryogenesis

“…In the past few years, cell signaling functions have been attributed to amelogenin low-mass isoforms such as LRAP (A-4/M59) ( Nebgen et al, 1999;Veis, 2003;Lacerda-Pinheiro et al, 2006a;Lacerda-Pinheiro et al, 2006b;Zeichner-David et al, 2006;Jegat et al, 2007,). The cell surface receptors for amelogenin (M180 and LRAP), were identified, and the exact binding regions of amelogenin to its receptors was deciphered Zou et al, 2007).…”

“…This is in line with the accumulating data on the signaling function of amelogenin, including our recent data (Haze et al in submission). Other studies in which low molecular mass amelogenin isoforms produced ectopically chondrogenic and osteogenic-like tissue and caused ameloblasts and odontoblasts differentiation suggested prenatal and postnatal signaling effects for the different amelogenin isoforms ( Nebgen et al, 1999;Veis, 2003;Lacerda-Pinheiro et al, 2006a;Lacerda-Pinheiro et al, 2006b;Jegat et al, 2007,) (also see introduction on possible signaling activity of amelogenin).…”

“…Low molecular mass amelogenin isoforms were suggested to be signal molecules; were shown to produce ectopically chondrogenic and osteogenic-like tissue and to have different signaling effects on ameloblasts and odontoblasts differentiation in developing tooth culture model, and when implanted in the tooth pulp ( Nebgen et al, 1999;Veis, 2003;Lacerda-Pinheiro et al, 2006a;LacerdaPinheiro et al, 2006b;Zeichner-David et al, 2006;Jegat et al, 2007). Amelogenin (M180), the amelogenin isoform LRAP (leucin-rich amelogenin peptide), and some of the amelogenin degradation products, were found to bind to the cell surface receptors; LAMP-1, LAMP-2 and CD63, which are ubiquitously expressed lysosomal integral membrane proteins that are also localized to the plasma membrane.…”

Leucine-rich amelogenin peptide induces osteogenesis in mouse embryonic stem cells

“…Analyses of the amelogenin constituents of Emdogain suggest that LRAP functions as a signaling molecule [10]. In the previous studies, LRAP has been found to induce osteogenesis in various cell types, including rat muscle fibroblasts [10], mouse cementoblasts [11], and mouse oral mucosal cells [12].…”

Amelogenin Peptide Extract Increases Differentiation and Angiogenic and Local Factor Production and Inhibits Apoptosis in Human Osteoblasts

“…These assembled structures undergo a slow, progressive proteolytic degradation that results in several polypeptide fragments that are released to the matrix [17,20,21]. These peptides as well as isoforms and splice variants of amelogenin can activate diverse functions in adjacent cells or tissues [22][23][24][25][26][27]. Two smaller amelogenin peptides, leucine-rich amelogenin peptide (LRAP) and tyrosine-rich amelogenin peptide (TRAP) [28], have been proposed to be the functional part of the intact amelogenin.…”