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Yasushi Toyoshima1 , Satoshi Tanaka1 , Kunio Shiota1 *
Laboratory of Cellular Biochemistry, Animal Resource Science/ Veterinary Medical Science, The University of Tokyo, Tokyo, Japan 1
PAL31, a novel molecule highly expressed in the fetal brain, possesses leucine-rich repeat and nuclear localization signal. A series of experiments revealed that PAL31 is also expressed in other proliferating cells in the adult tissue including spleen, testis and ovary. We assumed, therefore, that the molecule is a nuclear protein functioning in cellular proliferation. In the present study, we investigated the localization of PAL31 in the rat mammary gland, in which the cellular component markedly changes during the reproductive cycle, using the anti-PAL31 antibody. PAL31 signals were observed in the cells of mammary epithelium, connective tissue and capillary blood vessel in cycling and pregnant rats. The expression level fluctuated during the estrous cycle and markedly increased in the mammary gland during the pregnancy. Interestingly, the signal for PAL31 was observed both in nuclei and cytosol, suggesting the intracellular translocation depending on the cell cycle. Further analysis of nuclear localization by using confocal laser scanning microscopy indicated that PAL31 exists at the perinuclei area and inside the nucleus. More importantly, speckled signal of PAL31 was found in the nucleus only when PCNA was expressed. These results indicate that PAL31 is expressed in the mammary gland in association with the cell-proliferation, in which PAL31 is translocated from the cytosol into the nucleus at S phase.
This abstract is being presented on Tuesday, August 3 at 5:30 PM at Todd 125.