PAN2-PAN3 deadenylase activity is selectively required for mitotic robustness under microtubule stress

Abstract

HIGHLIGHTSO_LIPAN2-PAN3 catalytic activity is required for mitotic robustness under MT stress C_LIO_LICatalytic-dead Pan2-D1020A phenocopies pan2{Delta}: spindle defects and G2/M arrest C_LIO_LILoss of Pan2 catalytic activity amplifies nocodazole-induced changes in CLB1 and CLN3 mRNA C_LIO_LIPAN2 depletion in human cells produces multipolar spindles under MT stress C_LI IN BRIEFVerma et al. show that PAN2-PAN3 deadenylase catalytic activity is selectively required for mitotic fidelity under microtubule stress. Yeast pan2{Delta} cells exhibit spindle defects, G2/M arrest, and altered CLB1 and CLN3 mRNA levels under nocodazole. PAN2 knockdown in human cells produces multipolar spindles, demonstrating evolutionary conservation. Cytoplasmic deadenylation by PAN2-PAN3 and CCR4-NOT regulates mRNA stability and translation, but the contribution of individual deadenylases to mitotic progression is poorly defined. Here we show that PAN2-PAN3 catalytic activity is selectively required for mitotic robustness under microtubule stress. In budding yeast, the catalytically inactive Pan2-D1020A mutant fails to complement pan2{Delta} nocodazole sensitivity, leading to G2/M arrest, spindle defects, and increased cell death. pan2{Delta} exhibits synthetic genetic interactions with tubulin and tubulin-folding genes, and RNA-seq reveals dysregulation of cell-cycle transcripts including the cyclins CLB1 and CLN3. The phenotype is stress-conditional: pan2{Delta} cells proliferate normally without drug. In mammalian cells, PAN2 depletion sensitizes HEK293A cells to nocodazole and colchicine and produces prolonged metaphase with multipolar spindles. Together, these findings define a conserved, stress-conditional role for PAN2-PAN3 deadenylase activity in safeguarding mitotic fidelity when microtubules are compromised. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/591760v3_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@19e6662org.highwire.dtl.DTLVardef@53ba18org.highwire.dtl.DTLVardef@de9c99org.highwire.dtl.DTLVardef@fb0f9d_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO See accompanying graphical abstract file. C_FIG