A recent study by Mitrovic and Schachner (J Neurosci Res 42:710-717, 1
995) reported the detection of a small amount of truncated tenascin-C
(TN-C) in the nervous system of the TN-C knockout mice created by Saga
et al. (Genes Dev 6:1821-1831, 1992), The authors suggested that the
truncated protein might be responsible for the failure to detect any p
henotypic abnormalities in the knockout mice, We have reexamined the k
nockout mice in our laboratories by Western blot and immunocytochemist
ry, and have not detected any full-length or truncated TN-C protein, I
n addition, we note that the construction of the knockout gene deleted
the signal sequence, so if any residual truncated protein were produc
ed it would be trapped in the cytoplasm, and therefore inaccessible to
extracellular ligands or receptors, We therefore conclude that the TN
-C knockout created by Saga et al. is a valid TN-C null. (C) 1997 Wile
y-Liss, Inc.