Hyperphosphorylation amplifies UPF1 activity to resolve stalls in nonsense-mediated mRNA decay.

Many gene expression factors contain repetitive phosphorylation sites for single kinases, but the functional significance is poorly understood. Here we present evidence for hyperphosphorylation as a mechanism allowing UPF1, the central factor in nonsense-mediated decay (NMD), to increasingly attract downstream machinery with time of residence on target mRNAs. Indeed, slowing NMD by inhibiting late-acting factors triggers UPF1 hyperphosphorylation, which in turn enhances affinity for factors linking UPF1 to decay machinery. Mutational analyses reveal multiple phosphorylation sites contributing to different extents to UPF1 activity with no single site being essential. Moreover, the ability of UPF1 to undergo hyperphosphorylation becomes increasingly important for NMD when downstream factors are depleted. This hyperphosphorylation-dependent feedback mechanism may serve as a molecular clock ensuring timely degradation of target mRNAs while preventing degradation of non-targets, which, given the prevalence of repetitive phosphorylation among central gene regulatory factors, may represent an important general principle in gene expression

Upf1 ATPase-Dependent mRNP Disassembly Is Required for Completion of Nonsense- Mediated mRNA Decay

SummaryCellular mRNAs exist in messenger ribonucleoprotein (mRNP) complexes, which undergo transitions during the lifetime of the mRNAs and direct posttranscriptional gene regulation. A final posttranscriptional step in gene expression is the turnover of the mRNP, which involves degradation of the mRNA and recycling of associated proteins. How tightly associated protein components are released from degrading mRNPs is unknown. Here, we demonstrate that the ATPase activity of the RNA helicase Upf1 allows disassembly of mRNPs undergoing nonsense-mediated mRNA decay (NMD). In the absence of Upf1 ATPase activity, partially degraded NMD mRNA intermediates accumulate in complex with NMD factors and concentrate in processing bodies. Thus, disassembly and completion of turnover of mRNPs undergoing NMD requires ATP hydrolysis by Upf1. This uncovers a previously unappreciated and potentially regulated step in mRNA decay and raises the question of how other mRNA decay pathways release protein components of substrate mRNPs.PaperFlic

associations between general and abdominal adiposity and mortality in individuals with diabetes mellitus

Individuals with diabetes mellitus are advised to achieve a healthy weight to prevent complications. However, fat mass distribution has hardly been investigated as a risk factor for diabetes complications. The authors studied associations between body mass index, waist circumference, waist/hip ratio, and waist/height ratio and mortality among individuals with diabetes mellitus. Within the European Prospective Investigation into Cancer and Nutrition, a subcohort was defined as 5,435 individuals with a confirmed self-report of diabetes mellitus at baseline in 1992-2000. Participants were aged 57.3 (standard deviation, 6.3) years, 54% were men, the median diabetes duration was 4.6 (interquartile range, 2.0-9.8) years, and 22% of the participants used insulin. Body mass index, as indicator of general obesity, was not associated with higher mortality, whereas all measurements of abdominal obesity showed a positive association. Associations generally were slightly weaker in women. The strongest association was observed for waist/height ratio: In the fifth quintile, the hazard rate ratio was 1.88 (95% confidence interval: 1.33, 2.65) for men and 2.46 (95% confidence interval: 1.46, 4.14) for women. Measurements of abdominal, but not general, adiposity were associated with higher mortality in diabetic individuals. The waist/height ratio showed the strongest association. Respective indicators might be investigated in risk prediction models

A family outbreak of tinea capitis due to Trichophyton violaceum in Michigan. Its control with griseofulvin

An outbreak of tinea capitis caused by Trichophyton violaceum in five siblings of a family of eight in Michigan and its control with griseofulvin are described.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43276/1/11046_2005_Article_BF02145740.pd