Deficiency in a cytosolic ribose-5-phosphate isomerase causes chloroplast dysfunction, late flowering and premature cell death in Arabidopsis

The oxidative pentose phosphate pathway (oxPPP) is part of central metabolism, consisting of two distinct phases: the oxidative phase and the non-oxidative phase. The non-oxidative phase of the oxPPP generates carbon skeletons for the synthesis of nucleotides, aromatic amino acids, phenylpropanoids and their derivatives, which are essential for plant growth and development. However, it is not well understood how the non-oxidative phase of the oxPPP contributes to plant growth and development. Here, we report the characterization of Arabidopsis T-DNA knockout mutants of the RPI2 gene (At2g01290), which encodes a cytosolic ribose-5-phosphate isomerase (RPI) that catalyzes the reversible interconversion of ribulose-5-phosphate and ribose-5-phosphate in the non-oxidative phase of the oxPPP. Although recombinant Arabidopsis RPI2 protein exhibits marked RPI enzymatic activity, knockout of the RPI2 gene does not significantly change the total RPI activity in the mutant plants. Interestingly, knockout of RPI2 interferes with chloroplast structure and decreases chloroplast photosynthetic capacity. The rpi2 mutants accumulate less starch in the leaves and flower significantly later than wild-type when grown under short-day conditions. Furthermore, the rpi2 mutants display premature cell death in the leaves when grown at an above-normal temperature (26°C). These results demonstrate that a deficiency in the non-oxidative phase of the cytosolic oxPPP has pleiotropic effects on plant growth and development and causes premature cell death.     

Pharmacogenetic associations of MMP9 and MMP12 variants with cardiovascular disease in patients with hypertension

Objectives

MMP-9 and -12 function in tissue remodeling and may play roles in cardiovascular disease (CVD). We assessed associations of four MMP polymorphisms and three antihypertensive drugs with cardiovascular outcomes.

Methods

Hypertensives (n = 42,418) from a double-blind, randomized, clinical trial were randomized to chlorthalidone, amlodipine, lisinopril, or doxazosin treatment (mean follow up, 4.9 years). The primary outcome was coronary heart disease (CHD). Secondary outcomes included combined CHD, all CVD outcomes combined, stroke, heart failure (HF), and mortality. Genotype-treatment interactions were tested.

Results

There were 38,698 participants genotyped for at least one of the polymorphisms included here. For MMP9 R668Q (rs2274756), lower hazard ratios (HRs) were found for AA subjects for most outcomes when treated with chlorthalidone versus amlodipine (eg., CCHD: GG = 1.00, GA = 1.01, AA = 0.64; P = 0.038). For MMP9 R279Q (rs17576), modest pharmacogenetic findings were observed for combined CHD and the composite CVD outcome. For MMP12 N122S (rs652438), lower HRs were observed for CHD in subjects carrying at least one G allele and being treated with chlorthalidone versus lisinopril (CHD: AA = 1.07, AG = 0.80, GG = 0.49; P = 0.005). In the lisinopril-amlodipine comparison, higher HRs were observed for participants having at least one G allele at the MMP12 N122S locus (CHD: AA = 0.94, AG = 1.19, GG = 1.93; P = 0.041). For MMP12 −82A>G (rs2276109), no pharmacogenetic effect was found for the primary outcome, although lower HRs were observed for AA homozygotes in the chlorthalidone-amlodipine comparison for HF (P = 0.015).

Conclusions

We observed interactions between antihypertensive drugs and MMP9 and MMP12 for CHD and composite CVD. The data suggest that these genes may provide useful clinical information with respect to treatment decisions.     

Pyrimidinone-peptoid hybrid molecules with distinct effects on molecular chaperone function and cell proliferation

The Hsp70 molecular chaperones are ATPases that play critical roles in the pathogenesis of many human diseases, including breast cancer. Hsp70 ATP hydrolysis is relatively weak but is stimulated by J domain-containing proteins. We identified pyrimidinone-peptoid hybrid molecules that inhibit cell proliferation with greater potency than previously described Hsp70 modulators. In many cases, anti-proliferative activity correlated with inhibition of J domain stimulation of Hsp70.     

Properties of epinephrine-induced activation of cardiac adenosine 3′,5′-monophosphate-dependent protein kinase

The effects of epinephrine on cyclic AMP content and protein kinase activity were examined in an in situ rat heart preparation. Bolus injection of epinephrine into the superior vena cava caused an increase in the activity ratio (—cyclic AMP/+cyclic AMP) of 12 000 × g supernatant protein kinase. The increase was significant within 5 s and maximal in 10 s. Epinephrine produced a dose-dependent increase in both protein kinase activity ratio and cyclic AMP content. The increases in both parameters exhibited a high degree of correlation. The increase in protein kinase activity ratio observed with low doses of epinephrine (less than or equal to 1 μg/kg) resulted from an increase in independent protein kinase activity (—cyclic 2 AMP) without a change in total protein observ activity (+cyclic AMP). However, the increase in the activity ratio observed with higher doses of epinephrine (greater than 1 μg/kg) was due mainly to a decrease in total protein kinase activity rather than a further increase in independent protein kinase activity. The loss of supernatant total protein kinase activity could be accounted for by an increase in activity associated with particulate fractions obtained from the homogenates. A similar redistribution of protein kinase could be demonstrated by the addition of cyclic AMP to homogenates prepared from hearts not stimulated with epinephrine. These results demonstrate that epinephrine over a wide dose range produces a parallel increase in the content of cyclic AMP and the activation of soluble protein kinase. The findings also suggest that protein kinase translocation to particulate material may depend on the degree of epinephrine-induced enzyme activation.     

Population-specific home ranges and migration timing of Pacific Arctic beluga whales (Delphinapterus leucas)

Two populations of beluga whales (Delphinapterus leucas), the Eastern Beaufort Sea (BS) and Eastern Chukchi Sea (ECS), make extensive seasonal migrations into the Pacific Arctic. However, the extent to which these populations overlap in time and space is not known. We quantified distribution and migration patterns for BS and ECS belugas using daily locations from whales tracked with satellite-linked transmitters. Home ranges and core areas in summer (July and August) and in each month (July–November), daily displacement, dispersal from core areas, and autumn migration timing were estimated. Distinct summer and fall distribution patterns and staggered autumn migration timing were identified for BS and ECS whales. Summer home ranges for each population had less than 10 % overlap. Monthly home ranges were also relatively distinct between populations except in September (up to 88 % home range overlap). A distinct east–west shift in focal area use occurred in September that persisted into October, with the two populations essentially switching longitudinal positions. Highest daily displacements occurred during the migratory period in September for BS whales and October for ECS whales, further indicating westward fall migration was offset between populations. Sexual segregation of males and females within a population also varied monthly. Autumn migration timing as well as differences in spatial and temporal segregation between BS and ECS beluga populations may be a result of maternally driven philopatry and population-specific adaptations to dynamically available resources. Our results contribute to the management of these populations by identifying seasonal area use and differences in migration patterns.     

MRE11-Deficiency Associated with Improved Long-Term Disease Free Survival and Overall Survival in a Subset of Stage III Colon Cancer Patients in Randomized CALGB 89803 Trial

Purpose

Colon cancers deficient in mismatch repair (MMR) may exhibit diminished expression of the DNA repair gene, MRE11, as a consequence of contraction of a T₁₁ mononucleotide tract. This study investigated MRE11 status and its association with prognosis, survival and drug response in patients with stage III colon cancer.

Patients and Methods

Cancer and Leukemia Group B 89803 (Alliance) randomly assigned 1,264 patients with stage III colon cancer to postoperative weekly adjuvant bolus 5-fluorouracil/leucovorin (FU/LV) or irinotecan+FU/LV (IFL), with 8 year follow-up. Tumors from these patients were analyzed to determine stability of a T₁₁ tract in the MRE11 gene. The primary endpoint was overall survival (OS), and a secondary endpoint was disease-free survival (DFS). Non-proportional hazards were addressed using time-dependent covariates in Cox analyses.

Results

Of 625 tumor cases examined, 70 (11.2%) exhibited contraction at the T₁₁ tract in one or both MRE11 alleles and were thus predicted to be deficient in MRE11 (dMRE11). In pooled treatment analyses, dMRE11 patients showed initially reduced DFS and OS but improved long-term DFS and OS compared with patients with an intact MRE11 T₁₁ tract. In the subgroup of dMRE11 patients treated with IFL, an unexplained early increase in mortality but better long-term DFS than IFL-treated pMRE11 patients was observed.

Conclusions

Analysis of this relatively small number of patients and events showed that the dMRE11 marker predicts better prognosis independent of treatment in the long-term. In subgroup analyses, dMRE11 patients treated with irinotecan exhibited unexplained short-term mortality. MRE11 status is readily assayed and may therefore prove to be a useful prognostic marker, provided that the results reported here for a relatively small number of patients can be generalized in independent analyses of larger numbers of samples.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00003835","term_id":"NCT00003835"}}NCT00003835     

Regional mapping panel for human chromosome 17: Application to neurofibromatosis type 1

A somatic cell hybrid mapping panel was constructed to localize cloned DNA sequences to any of 15 potentially different regions of human chromosome 17. Relatively high-resolution mapping is possible for 50% of the chromosome length in which 12 breakpoints are distributed over approximately 45 megabases, with an average spacing estimated at 1 breakpoint every 2-7 megabases. This high-resolution capability includes the pericentromeric region of 17 to which von Recklinghausen neurofibromatosis (NF1) has recently been mapped. Using 20 cloned genes and anonymous probes, we have tested the expected order and location of panel breakpoints and confirmed, refined, or corrected the regional assignment of several cloned genes and anonymous probes. Four markers with varying degrees of linkage to NF1 have been physically localized and ordered by the panel: the loosely linked markers myosin heavy chain 2 (25 cM) to p12----13.105 and nerve growth factor receptor (14 cM) to q21.1----q23; the more closely linked pABL10-41 (D17S71, 5 cM) to p11.2; and the tightly linked pHHH202 (D17S33) to q11.2-q12. Thus, physical mapping of linked markers confirms a pericentromeric location of NF1 and, along with other data, suggests the most likely localization is proximal 17q.     

Incidence and Identification of Pseudomonas fluorescens and Pseudomonas putida in the Clinical Laboratory

Strains of Pseudomonas producing fluorescin but no pyocyanin or pyorubrin were studied by biochemical and antibiotic sensitivity testing. A rapid nitrate test was found to be useful in distinguishing P. aeruginosa (positive) from P. fluorescens and P. putida (both negative). A shortened gelatin test differentiated P. fluorescens (positive) from P. putida (negative). P. fluorescens and P. putida were very sensitive to low levels of kanamycin and resistant to carbenicillin, a pattern just the opposite of that obtained with P. aeruginosa.     

The human LSm1-7 proteins colocalize with the mRNA-degrading enzymes Dcp1/2 and Xrnl in distinct cytoplasmic foci

Sm and Sm-like (LSm) proteins form heptameric complexes that are involved in various steps of RNA metabolism. In yeast, the Lsm1-7 complex functions in mRNA degradation and is associated with several enzymes of this pathway, while the complex LSm2-8, the composition of which largely overlaps with that of LSm1-7, has a role in pre-mRNA splicing. A human gene encoding an LSm1 homolog has been identified, but its role in mRNA degradation has yet to be elucidated. We performed subcellular localization studies and found hLSm1 predominantly in the cytoplasm. However, it is not distributed evenly; rather, it is highly enriched in small, discrete foci. The endogenous hLSm4 is similarly localized, as are the overexpressed proteins hLSm1-7, but not hLSm8. The foci also contain two key factors in mRNA degradation, namely the decapping enzyme hDcp1/2 and the exonuclease hXrn1. Moreover, coexpression of wild-type and mutant LSm proteins, as well as fluorescence resonance energy transfer (FRET) studies, indicate that the mammalian proteins hLSm1-7 form a complex similar to the one found in yeast, and that complex formation is required for enrichment of the proteins in the cytoplasmic foci. Therefore, the foci contain a partially or fully assembled machinery for the degradation of mRNA.