MURINE INTERLEUKIN-11 (IL-11) IS EXPRESSED AT HIGH-LEVELS IN THE HIPPOCAMPUS AND EXPRESSION IS DEVELOPMENTALLY-REGULATED IN THE TESTIS

IL-11, derived from a bone marrow stromal cell line, has pleiotropic e ffects on both hematopoietic cells and nonhematopoietic cells. However , no previous studies have systematically addressed expression of IL-l l in primary tissues in vivo and the relationship of IL-11 tissue spec ific gene expression and function of IL-11 is not clear. In the presen t study, we examined constitutive IL-11 expression in various murine a dult tissues in vivo. IL-ll mRNA is expressed in a wide range of norma l tissues (including hematopoietic organs) at levels only detected by RT-PCR. IL-ll protein was detected in brain and testis by Western blot analysis. The in vivo cellular distribution of IL-11 expression was e xamined by in situ hybridization. In brain, IL-ll message is distribut ed in granular layer dentate gyrus and pyramidal cell layers of hippoc ampus. IL-11 is also expressed in anterior horn cells and lateral colu mn neuronal cells of the spinal cord. In testis, IL-11 mRNA is express ed in round spermatids at stage VI-IX seminiferous tubules. IL-11 expr ession in testis is restricted to developing spermatogonia and is deve lopmentally regulated, since no expression is seen in mice genetically deficient in germ cells and in mice prior to sexual maturation. These expression data correlate with functional data demonstrating that IL- 11 stimulates proliferation in vitro of a hippocampus neuronal progeni tor cell line and administration of IL-ll in vivo accelerates recovery of spermatogenesis after cytotoxic therapy. These studies suggest tha t IL-11 may be an important regulator in neural and testicular functio n. (C) 1996 Wiley-Liss, Inc.