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Regulation of gene expression in kinetoplastid mitochondria is largely post-transcriptional and involves the orchestration of polycistronic RNA processing, 3-terminal maturation, RNA editing, turnover, and translation; however, these processes remain poorly studied. Core editing complexes and their U-insertion/deletion activities are relatively well characterized, and a battery of ancillary factors has recently emerged. This study characterized a novel DExH-box RNA helicase, termed here REH2 (RNA editing associated helicase 2), in unique ribonucleoprotein complexes that exhibit unwinding and guide RNA binding activities, both of which required a double-stranded RNA-binding domain (dsRBD) and a functional helicase motif I of REH2. REH2 complexes and recently identified related particles share a multiprotein core but are distinguished by several differential polypeptides. Finally, REH2 associates transiently, via RNA, with editing complexes, mitochondrial ribosomes, and several ancillary factors that control editing and RNA stability. We propose that these putative higher order structures coordinate mitochondrial gene expression.Unique gene expression mechanisms in kinetoplastid flagellates include U-insertion/deletion RNA editing by concerted cycles of cleavage, U-addition/removal, and ligation that can create hundreds of amino acid codons in most mitochondrial mRNAs (1, 2). The RNA editing core complex (RECC) 4 contains 18 -20 subunits (3-6), although a few subunits seem to exchange in substrate-specific variants of this complex (7). The RECC acronym was recently introduced by Simpson et al. (55). Editing complexes recognize partial helices between pre-mRNA and complementary guide RNAs (gRNAs) initially stabilized by a short "anchor" duplex (6,8,9). Substrate determinants for duplex binding and nuclease specificity (6, 10, 11) and substrate structure in solution (12-14) have been characterized.Several accessory factors, mostly in multisubunit arrays, have been proposed to modulate RNA editing during catalysis, substrate production, or RNA turnover. The MRP complex has RNA annealing activity in vitro and may promote mRNA and gRNA pairing (15, 16). Post-transcriptional mRNA terminal 3Ј-poly(A)/(U) and gRNA 3Ј-poly(U) maturation are mediated by KPAP1 and RET1 complexes (17,18). MRB1, TbRGG1, and GRBC complexes proposed to contain between 14 and 24 proteins (termed here MRB-related complexes) share several components, but their functional relationship remains unclear. Repression of a few common subunits inhibited RNA editing and in some cases also decreased the level of total gRNA. GRBC1 and GRBC2 co-purified with RECC subunits (18 -24). MERS1, MRP, and RBP16 proteins were associated with mRNA stability (23, 25). RBP16 also stimulated RNA insertion in vitro (26,27). DEAD-box mHel61 (also termed REH1) is the only predicted helicase known to impact RNA editing (28). Most of these proteins are likely to have additional roles outside editing. RNA helicases are common across species and typically multifunctional; howev...

BackgroundMinimally invasive parathyroidectomy (MIP) is the preferred approach to primary hyperparathyroidism (PHPT) when a single adenoma can be localized preoperatively. The added value of intraoperative parathyroid hormone (IOPTH) monitoring remains debated because its ability to prevent failed parathyroidectomy due to unrecognized multiple gland disease (MGD) must be balanced against assay-related costs. We used a decision tree and cost analysis model to examine IOPTH monitoring in localized PHPT.MethodsLiterature review identified 17 studies involving 4,280 unique patients, permitting estimation of base case costs and probabilities. Sensitivity analyses were performed to evaluate the uncertainty of the assumptions associated with IOPTH monitoring and surgical outcomes. IOPTH cost, MGD rate, and reoperation cost were varied to evaluate potential cost savings from IOPTH.ResultsThe base case assumption was that in well-localized PHPT, IOPTH monitoring would increase the success rate of MIP from 96.3 to 98.8%. The cost of IOPTH varied with operating room time used. IOPTH reduced overall treatment costs only when total assay-related costs fell below $110 per case. Inaccurate localization and high reoperation cost both independently increased the value of IOPTH monitoring. The IOPTH strategy was cost saving when the rate of unrecognized MGD exceeded 6% or if the cost of reoperation exceeded $12,000 (compared with initial MIP cost of $3733). Setting the positive predictive value of IOPTH at 100% and reducing the false-negative rate to 0% did not substantially alter these findings.ConclusionsInstitution-specific factors influence the value of IOPTH. In this model, IOPTH increased the cure rate marginally while incurring approximately 4% additional cost.

Background:The mechanism by which XPD helicase acquires its Fe-S cluster is unknown. Results: XPD associates with the CIA targeting complex or TFIIH in two mutually exclusive protein complexes. Blocking Fe-S cluster assembly on XPD inhibits its incorporation into TFIIH. Conclusion: XPD maturation is a stepwise process in which XPD acquires its Fe-S cluster before binding TFIIH. Significance: The XPD-CIA targeting complex interaction is required for TFIIH assembly.

Background: Radioactive iodine (RAI) ablation is frequently performed after initial surgery for welldifferentiated thyroid cancer (WDTC). We examined the frequency and timing of childbirth as well as nononcologic complications after RAI ablation for WDTC on a population level. Methods: A retrospective cohort study of 25,333 patients (18,850 women) with WDTC was performed using the California Cancer Registry and California Office of Statewide Health Planning and Development database, 1999-2008. The primary outcomes were birthrate and median time to first live birth among women of childbearing age. Secondary outcomes were nononcologic diagnoses occurring outside the acute setting ( > 30 days) after ablation. Results: RAI ablation did not affect birthrate among women in the full dataset. However, in subgroup analyses, birthrate among women age 35-39 was significantly decreased in those who received RAI versus those who did not (11.5 versus 16.3 births per 1000 woman-years, p < 0.001). Median time to first live birth after diagnosis of WDTC was prolonged among women who received RAI compared to those who did not (34.5 versus 26.1 months; p < 0.0001). When 5-year age groups were examined individually, delay to first live birth was observed in women age 20-39 ( p < 0.05). This remained significant after adjustment for tumor characteristics, socioeconomic status, and marital status. The only nononcologic, nonreproductive adverse effect associated with RAI ablation was an increased rate of nasolacrimal stenosis (RR 3.44, p < 0.0001). Conclusions: RAI ablation is associated with delayed childbearing in women across most of the reproductive lifespan, and with decreased birthrate in the late reproductive years. The underlying mechanism likely involves physician recommendation to delay pregnancy, as well as a potential impact of RAI on both reproductive choice and reproductive health. Further investigation is merited.