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. Author manuscript; available in PMC: 2011 May 14.
Published in final edited form as: Mol Cell. 2010 May 14;38(3):345–355. doi: 10.1016/j.molcel.2010.02.039

Figure 5. The 5′-3′ mRNA Decay Pathway Targets HSP26 mRNAs in igo1Δ igo2Δ Mutants.

Figure 5

(A) Loss of Dhh1, Ccr4, or Xrn1 suppresses the defect of igo1Δ igo2Δ, but not that of rim15Δ cells, in rapamycin-induced HSP26 mRNA expression. Northern analyses of HSP26 and of rapamycin-repressible SSB1 were done with wild-type and indicated mutant strains prior to (0) and following a rapamycin treatment (RAP; 0.2 μg ml-1) of 1 hr or 2 hr. Bar graphs show the relative level of HSP26 mRNA per rRNA (quantified by PhosphorImager analysis and arbitrarily set to 1.0 for exponentially growing wild-type cells). All samples were run on the same gel (identical film exposure time). Similar results were obtained for other genes (e.g., SOL4 and DCS2; Figure S3A).

(B, C) Loss of Dhh1 or Ccr4, but not loss of Xrn1, suppresses the defect of igo1Δ igo2 in rapamycin-induced Hsp26 protein expression. (B) Cell extracts from the same strains as in (A), treated (2 hr, 4 hr, and 6 hr) or not (0 hr) with rapamycin, were analyzed by SDS-PAGE and immunoblots were probed with specific anti-Hsp26 antibodies. Ponceau S staining of the membranes prior to Immunoblot analysis served as loading control. (C) HSP26-lacZ expression was monitored (as in Figure 2D) in exponentially growing cells prior to (EXP) and following a 6-hr rapamycin treatment (RAP). Data are reported as averages (n = 3), with SDs indicated by the lines above each bar. Strains were as in (A). Please see Figure S3B for northern blot analyses.