The complex of the yeast Lsm1p-7p proteins with Pat1p is an important mRNA decay factor that is involved in translational shutdown of deadenylated mRNAs and thus prepares these mRNAs for degradation. While the Lsm proteins are highly conserved, there is no unique mammalian homolog of Pat1p. To identify proteins that interact with human LSm1, we developed a novel immunoprecipitation technique that yields virtually pure immunocomplexes. Mass-spec analysis therefore identifies mostly true positives, avoiding tedious functional screening. The method unambiguously identified the Pat1p homolog in HeLa cells, Pat1b. When targeted to a reporter mRNA, Pat1b represses gene expression by inducing deadenylation of the mRNAs. This demonstrates that Pat1b, unlike yPat1p, acts as an mRNA-specific deadenylation factor, highlighting the emerging importance of deadenylation in the mRNA regulation of higher eukaryotes.

Objective:To investigate the role of the HS1,2 enhancer polymorphisms as a new candidate marker for rheumatoid arthritis (RA) and to define the possible association with autoantibody positivity and clinical outcome.Methods:Genomic DNA was obtained from two cohorts of patients with RA (100 with early RA (ERA) and 114 with longstanding RA (LSRA)) and from 248 gender-matched controls from the same geographical area. Clinical and immunological characteristics were recorded for all the patients.Results:The percentage of the 2/2 genotype was higher in patients with ERA (27.0%), and in patients with LSRA (34.2%), than in controls (14.9%) (ERA: OR = 2.11 (95% CI 1.20 to 3.70) vs controls; LSRA: OR = 2.96 (95% CI 1.76 to 5.00) vs controls). A lower representation of allele *3 was present in patients with ERA (2.0%) than in controls (6.0%; OR = 0.32 (95% CI 0.11 to 0.91)). No significant associations were found between polymorphisms and autoantibodies positivity.Conclusion:The HS1,2A allele *2 associates with early and longstanding RA.