Developmental expression of pim kinases suggests functions also outside of the hematopoietic system

We have cloned a novel quail cDNA with strong homology to the pim family of proto-oncogenes. The deduced amino acid (aa) sequence of the cDNA, named qpim, is more closely related to Xenopus Pim and to the recently identified rat Pim-3 than to human or rodent Pim-1 or Pim-2. The protein encoded by the qpim cDNA can autophosphorylate itself and share substrates with murine Pim-1, suggesting functional redundancy to other Pim family serine/threonine kinases. We have compared the expression of qpim in avian embryos to mouse pim-1, -2 and -3 by in situ hybridization. qpim shows a highly dynamic expression pattern, particularly at early developmental stages. Surprisingly, its expression pattern is not identical to any of the murine pim genes, which show complementary and/or partially overlapping expression sites both in- and outside of the hematopoietic system. Altogether, our results suggest novel functions for Pim family kinases during embryonic development, in particular in epithelia and in the central nervous system.