Characterization of N-cadherin messenger RNA and polypeptide expression in rat

The cell adhesion molecule N-cadherin is a member of the cadherin gene superfamily. The protein is involved in morphogenetic processes, including neurite extension. In this study, N-cadherin mRNA and polypeptide expression were investigated in rat brain, liver, muscle, heart, kidney and lung during postnatal development and aging. Six synthetic oligonucleotide probes covering different parts of mouse N-cadherin cDNA all hybridized to 5.2, 4.3-4.4 and 3.5 kb mRNAs in rat tissues. The mRNA pattern differed between tissues and, furthermore, the amount of N-cadherin mRNA and polypeptides in brain, liver and heart was higher than in muscle, kidney and lung. N-cadherin expression decreased slightly during early postnatal development in all tissues, whereas no changes in N-cadherin expression were observed during aging. Antibodies against a fusion protein containing the transmembrane and cytoplasmic sequence of chick N-cadherin were produced. These antibodies, termed anti-N-cad-cyt, were compared to the R-156 antibodies which recognize the 24 C-terminal amino acids of N-cadherin and which have been shown to react with a broad spectrum of cadherins. Using these two antibodies, it was shown that the 130 kDa N-cadherin polypeptide was subject to calcium-dependent cleavage of the cytoplasmic domain. Conversely, in the absence of calcium the polypeptide was cleaved extracellularly, producing two C-terminal fragments of 85 and 95 kDa. A 122 kDa polypeptide was recognized by both antibodies and may be either an alternatively spliced form of N-cadherin or a closely related cadherin.