The lamin Dm0 allele Ari3 acts as an enhancer of position effect variegation of the wm4 allele in Drosophila.

The association of lamin and lamin binding proteins with peripheral heterochromatin suggests the possibility that lamins may influence gene expression by participating in the epigenetic regulation of chromatin stucture. To test this hypothesis we have examined the effect of a recently generated partial loss-of-function lamin Dm0 allele Ari3 on PEV of the wm4 allele in the Drosophila eye. The Lam ( Ari3 ) allele is characterized by a truncation of the COOH-terminal domain and lacks the CaaX box that localizes lamin to the inner nuclear membrane. We show that the Lam ( Ari3 ) allele strongly increased silencing of wm4 expression, thus acting as an enhancer of PEV. These results indicate that lamins may be involved in regulating gene silencing and heterochromatic spreading at the wm4 locus and provide evidence that lamins may contribute to the regulation of higher-order chromatin organization.