| Summary: | <p>Abstract</p> <p>Background</p> <p>A number of transgenic mice carrying different deletions in the Locus Control Region (LCR) of the mouse <it>tyrosinase (Tyr) </it>gene have been developed and analysed in our laboratory. We require melanocytes from these mice, to further study, at the cellular level, the effect of these deletions on the expression of the <it>Tyr </it>transgene, without potential interference with or from the endogenous <it>Tyr </it>alleles. It has been previously reported that it is possible to obtain and immortalise melanocyte cell cultures from postnatal mouse skin.</p> <p>Results</p> <p>Here, we describe the efforts towards obtaining melanocyte cultures from our <it>Tyr </it>transgenic mice. We have bred our <it>Tyr </it>transgenic mice into <it>Tyr </it><sup><it>c</it>-32<it>DSD </it></sup>mutant background, lacking the endogenous <it>Tyr </it>locus. In these conditions, we failed to obtain immortalised melanocytes. We decided to include the inactivation of the <it>Ink4a-Arf </it>locus to promote melanocyte immortalisation. For this purpose, we report the segregation of the <it>Ink4a-Arf </it>null allele from the <it>brown </it>(<it>Tyrp1</it><sup><it>b</it></sup>) mutation in mice. Finally, we found that <it>Ink4a-Arf </it><sup>+/- </sup>and <it>Ink4a-Arf </it><sup>-/- </sup>melanocytes had undistinguishable tyrosine hydroxylase activities, although the latter showed reduced cellular pigmentation content.</p> <p>Conclusion</p> <p>The simultaneous presence of precise genomic deletions that include the <it>tyrosinase </it>locus, such as the <it>Tyr </it><sup><it>c</it>-32<it>DSD </it></sup>allele, the <it>Tyr </it>transgene itself and the inactivated <it>Ink4a-Arf </it>locus in <it>Tyrp1</it><sup><it>B </it></sup>genetic background appear as the crucial combination to perform forthcoming experiments. We cannot exclude that <it>Ink4a-Arf </it>mutations could affect the melanin biosynthetic pathway. Therefore, subsequent experiments with melanocytes will have to be performed in a normalized genetic background regarding the <it>Ink4a-Arf </it>locus.</p>
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