Generation of the dominant-negative mutant of hArpNβ:: A component of human SWI/SNF chromatin remodeling complex

hArpN beta, an actin-related protein located within the nucleus, is a subunit of the human SWI/SNF chromatin remodeling complex. hArpN beta has been proposed to regulate the assembly and activity of the hSWI/SNF complex. Sequence comparisons of the potential ArpN homologs with beta -actin showed that the ArpNs have the divergent subdomains Ib and IIb in addition to the unique N-terminal short insert, MS(G/A)-(V/L)YGG. Since the proposed function of hArpN beta requires more than two distinct but concurrently operating surfaces, we examined whether the disruption of one operating surface of hArpN beta results in dominant-negative phenotype. When overexpressed in HeLa or 293T cells, the subdomain Ib or IIb hybrids, in which the subdomain Ib or IIb of hArpN beta was replaced with that of beta -actin, respectively, showed no effect on cell survival. On the other hand, the overexpression of the N-terminal deletion mutant of hArpN beta resulted in cell death probably through apoptotic process. These results indicate that the proper function of hArpN beta is essential for cell survival in human cells. Furthermore, they suggests the possibility that the N-terminal short sequence is indispensable for the chromatin remodeling activity or the assembly of the hSWI/SNF complex after the binding of hArpN beta with functionally essential partner proteins. (C) 2001 Academic Press.