Sus1 maintains a normal lifespan through regulation of TREX-2 complex-mediated mRNA export

Abstract

Eukaryotic gene expression requires multiple cellular events, including transcription and RNA processing and transport. Sus1, a common subunit in both the Spt-Ada-Gcn5 acetyltransferase (SAGA) and transcription and export complex-2 (TREX-2) complexes, is a key factor in coupling transcription activation to mRNA nuclear export. Here we present that the SAGA DUB module and TREX-2 regulates distinctly yeast replicative lifespan in a Sir2-dependent and - independent manner, respectively. The growth and lifespan impaired by SUS1 loss depend on TREX-2 but not on the SAGA DUB module. Notably, an increased dosage of the mRNA export factors Mex67 and Dbp5 rescues the growth defect, shortened lifespan, and nuclear accumulation of poly(A)+ RNA in sus1{Delta} cells, suggesting that boosting the mRNA export process restores the mRNA transport defect and damage in the growth and lifespan of sus1{Delta} cells. Moreover, Sus1 is required for the proper association of Mex67 and Dbp5 with the nuclear rim. Together, these data suggest that Sus1 links transcription and mRNA nuclear export to the lifespan control pathway, indicating that prevention of an abnormal accumulation of nuclear RNA is necessary for maintaining a normal lifespan.