Le Norcy Elvire, Lesieur Julie, Sadoine Jeremy, Rochefort Gaël Y, Chaussain Catherine, Poliard Anne
EA2496 Faculté de Chirurgie Dentaire, Université Paris Descartes USPC, Paris, France.
APHP, Hôpital Bretonneau, Service d'Odontologie, Paris, France.
Front Physiol. 2018 Feb 8;9:55. doi: 10.3389/fphys.2018.00055. eCollection 2018.
The Leucine Rich Amelogenin Peptide (LRAP) is a product of alternative splicing of the gene. As full length amelogenin, LRAP has been shown, in precipitation experiments, to regulate hydroxyapatite (HAP) crystal formation depending on its phosphorylation status. However, very few studies have questioned the impact of its phosphorylation status on enamel mineralization in biological models. Therefore, we have analyzed the effect of phosphorylated (+P) or non-phosphorylated (-P) LRAP on enamel formation in ameloblast-like cell lines and cultures of murine postnatal day 1 molar germs. To this end, the mineral formed was analyzed by micro-computed tomography, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy, Selected Area Electon Diffraction imaging. gene transcription was evaluated by qPCR analysis. Our data show that, in both cells and germ cultures, LRAP is able to induce an up-regulation of transcription independently of its phosphorylation status. Mineral formation is promoted by LRAP(+P) in all models, while LRAP(-P) essentially affects HAP crystal formation through an increase in crystal length and organization in ameloblast-like cells. Altogether, these data suggest a differential effect of LRAP depending on its phosphorylation status and on the ameloblast stage at the time of treatment. Therefore, LRAP isoforms can be envisioned as potential candidates for treatment of enamel lesions or defects and their action should be further evaluated in pathological models.
富含亮氨酸的釉原蛋白肽（LRAP）是该基因可变剪接的产物。与全长釉原蛋白一样，在沉淀实验中，LRAP已被证明可根据其磷酸化状态调节羟基磷灰石（HAP）晶体的形成。然而，很少有研究探讨其磷酸化状态对生物模型中釉质矿化的影响。因此，我们分析了磷酸化（+P）或非磷酸化（-P）的LRAP对成釉细胞样细胞系和出生后第1天小鼠磨牙胚培养物中釉质形成的影响。为此，通过显微计算机断层扫描、场发射扫描电子显微镜、透射电子显微镜、选区电子衍射成像对形成的矿物质进行了分析。通过qPCR分析评估基因转录。我们的数据表明，在细胞和胚培养物中，LRAP能够上调转录，而与其磷酸化状态无关。在所有模型中，LRAP（+P）促进矿物质形成，而LRAP（-P）主要通过增加成釉细胞样细胞中晶体的长度和排列来影响HAP晶体的形成。总之，这些数据表明LRAP根据其磷酸化状态和治疗时的成釉细胞阶段具有不同的作用。因此，可以设想LRAP异构体是治疗釉质病变或缺陷的潜在候选物，其作用应在病理模型中进一步评估。
