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, incl uding neurite extension. In this study, N-cadherin mRNA and polypeptid e expression were investigated in rat brain, liver, muscle, heart, kid ney and lung during postnatal development and aging. Six synthetic oli gonucleotide 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 mR NA pattern differed between tissues and, furthermore, the amount of N- cadherin mRNA and polypeptides in brain, liver and heart was higher th an in muscle, kidney and lung. N-cadherin expression decreased slightl y during early postnatal development in all tissues, whereas no change s in N-cadherin expression were observed during aging. Antibodies agai nst a fusion protein containing the transmembrane and cytoplasmic sequ ence of chick N-cadherin were produced. These antibodies, termed anti- N-cad-cyt, were compared to the R-156 antibodies which recognize the 2 4 C-terminal amino acids of N-cadherin and which have been shown to re act with a broad spectrum of cadherins. Using these two antibodies, it was shown that the 130 kDa N-cadherin polypeptide was subject to calc ium-dependent cleavage of the cytoplasmic domain. Conversely, in the a bsence of calcium the polypeptide was cleaved extracellularly, produci ng two C-terminal fragments of 85 and 95 kDa. A 122 kDa polypeptide wa s recognized by both antibodies and may be either an alternatively spl iced form of N-cadherin or a closely related cadherin.