Cloning, Characterization, and Tissue Expression Pattern of Mouse Tuftelin cDNA

Abstract

Tuftelin is a protein that has been suggested to function during enamel crystal nucleation. Published sequences for bovine tuftelin cDNA and genomic clones proposed different reading frames that radically affected the derived amino acid sequence of the tuftelin carboxyl-terminus. We have isolated and characterized a full-length mouse cDNA clone and a partial porcine cDNA clone that include the region of the proposed frame-shift. The mouse tuftelin clone is 2572 nucleotides in length, exclusive of the poly(A+) tail. Translation from the 5'-most ATG yields a protein of 390 amino acids with an isotope-averaged molecular mass of 44.6 kDa and an isoelectric point of 5.9. Comparison of the bovine, mouse, and porcine cDNAs supports the revised bovine tuftelin amino acid sequence and suggests that the bovine tuftelin translation initiation codon be re-assigned to a more 5' ATG. Re-assigning the translation initiation codon lengthens the tuftelin protein by 52 amino acids, 51 of which are identical between bovine and mouse. At the carboxyl-terminus, the revised bovine and the mouse sequences match at 39 of the final 42 amino acid positions, compared with 2 identities with the originally published bovine reading frame. Northern blot analysis reveals that tuftelin is not ameloblast-specific but is expressed in multiple tissues, including kidney, lung, liver, and testis. Two tuftelin RNA messages, of 2.6 and 3.2 kb, were detected. DNA sequence characterization of an RT-PCR amplification product confirmed expression of tuftelin in kidney, and identified an alternatively spliced mouse tuftelin mRNA lacking exon 2.

PERP regulates enamel formation via effects on cell–cell adhesion and gene expression

“…The life cycle of ameloblasts involves several stages (Smith and Nanci, 1995). First, the presecretory ameloblasts differentiate into secretory ameloblasts, which deposit an extracellular matrix comprising proteins such as amelogenin, ameloblastin, enamelin, tuftelin and matrix metalloproteinase-20 (MMP-20) MacDougall et al, 1998;Stephanopoulos et al, 2005), and mineralization is initiated. A shift from matrix deposition to resorption occurs at the transitional and mature stages as MMP-20, kallikrein-4 (Hu et al, 2007;Stephanopoulos et al, 2005), amelotin (Iwasaki et al, 2005;Moffatt et al, 2006) and Odam (Moffatt et al, 2008) are predominantly expressed.…”

Expresión de Tuftelina en Gérmenes Dentales Humanos

“…Estudios previos realizados en modelos animales indican que la tuftelina es sintetizada por los ameloblastos durante las etapas tempranas del desarrollo del esmalte, y, continúa presente en el esmalte extracelular durante su desarrollo y mineralización (Deutsch et al, 1995;MacDougall et al, 1998;Zeichner-David, 2001;Mao et al, 2001;Satchell et al, 2002) En esta investigación se analizaron maxilares superiores e inferiores de fetos humanos; se corroboró que la secreción de la proteína es sintetizada desde etapas tempranas del desarrollo del órgano dental y en el esmalte en desarrollo, no así en el esmalte extracelular mineralizado.…”

“…Simmer & Hu et al, 2002). Esta proteína no es específica del órgano dental, ya que se ha encontrado que se expresa en otros tejidos incluyendo riñón, hígado, pulmón y testícu-los, debido a esto se cree que tiene una función fisiológica más general, que pudiera ser el desarrollo de éstos tejidos, pero aún no ha sido determinada (MacDougall et al, 1998;Satchell et al, 2002).…”

“…El que la tuftelina se encuentre en proximidad de la DEJ puede indicar su relacion en la nucleación de los cristales del esmalte (Satchell et al, 2002;Luo et al, 2004). De acuerdo a los resultados obtenidos es posible suponer que la tuftelina no solamente se expresa durante el proceso de amelogenesis, sino en el de odontogénesis, pero en tejidos no mineralizados (MacDougall et al, 1998;Luo et al, 2004), por lo que aunque el rol de la tuftelina en el desarrollo del esmalte todavía no se ha clarificado, lo cual puede indicar que esta proteína juega un papel importante en la biomineralización de esmalte y dentina, con lo anterior se deduce que una déficit o ausencia de tuftelina derivara en un transtorno de mineraliacion de esmalte y dentina de manto.…”

Localization, quantification, and characterization of tuftelin in soft tissues

“…Further search of the human and mouse expressed sequence tag (EST) databases (Mao et al, 2001;Deutsch et al, 2002) and Northern blot analysis (MacDougall et al, 1998) revealed that, in addition to tuftelin expression in the developing and mineralizing enamel, partial tuftelin cDNA sequences were also detected in many normal as well as cancerous soft tissues. Initial studies indicated that tuftelin protein is also synthesized in some of these tissues, such as eye, stomach, brain, and kidney (Mao et al, 2001;Deutsch et al, 2002).…”