Time-imposed daily restricted feeding induces rhythmic expression of Fgf21 in white adipose tissue of mice

Fibroblast growth factor 21 (FGF21) is a key metabolic regulator that is induced by fasting and starvation, and its expression is thought to be regulated by the circadian clock in the liver. To evaluate the functional role of FGF21 in the circadian regulation of physiology and behavior, we examined the temporal expression profiles of Fgf21 and circadian clock genes in addition to behavioral activity rhythms under adlibitum feeding (ALF) and time-imposed restricted feeding (RF) in mice. Four hours of daily restricted feeding during the daytime induced over an 80-fold increase in feeding-dependent rhythmic Fgf21 mRNA expression in epididymal white adipose tissue (eWAT), although the expression levels were continuously increased 10-fold in the liver of wild-type (WT) mice. Refeeding subsequent to transient fasting revealed that refeeding but not fasting remarkably induces Fgf21 expression in eWAT, although fasting-induced hepatic Fgf21 expression is completely reversed by refeeding. The free-running period of locomotor activity rhythm under ALF and the food anticipatory activity (FAA) under RF remained intact in Fgf21 knockout (KO) mice, suggesting that FGF21 is dispensable for both the central clock in the suprachiasmatic nucleus (SCN) and the food-entrainable oscillator that governs the FAA. Temporal expression profiles of circadian genes such as mPer2 and BMAL1 were essentially identical in both tissues between WT and Fgf21 KO mice under RF. The physiological role of the refeeding-induced adipose Fgf21 expression remains to be elucidated.     

Secreted Wnt "inhibitors" are not just inhibitors: regulation of extracellular Wnt by secreted Frizzled-related proteins

Gradient formation and signaling ranges of secreted proteins are crucial problems to understand how morphogens work for positional information and patterning in animal development. Yet, extracellular behaviors of secreted signaling molecules remain unexplored compared to their downstream pathways inside the cell. Recent advances in bioimaging make it possible to directly visualize morphogen molecules, and this simple strategy has, at least partly, succeeded in uncovering molecular behaviors of morphogens, such as Wnt (wingless-type MMTV integration site family member) and BMP (bone morphogenetic protein) as well as secreted Wnt binding proteins, sFRPs (secreted Frizzled-related proteins), in embryonic tissues. Here, we review the regulation of Wnt signaling by sFRPs, focusing on extracellular regulation of Wnt ligands in comparison with other morphogens. We also discuss evolutionary aspects with comprehensive syntenic and phylogenetic information about vertebrate sfrp genes. We newly annotated several sfrp genes including sfrp2-like 1 (sfrp2l1) in frogs and fishes and crescent in mammals.     

Estimating the flexural rigidity of Arabidopsis inflorescence stems: Free-vibration test vs. three-point bending test

The mechanical strength of a plant stem (a load-bearing organ) helps the plant resist drooping, buckling and fracturing. We previously proposed a method for quickly evaluating the stiffness of an inflorescence stem in the model plant Arabidopsis thaliana based on measuring its natural frequency in a free-vibration test. However, the relationship between the stiffness and flexural rigidity of inflorescence stems was unclear. Here, we compared our previously described free-vibration test with the three-point bending test, the most popular method for calculating the flexural rigidity of A. thaliana stems, and examined the extent to which the results were correlated. Finally, to expand the application range, we present an example of a modified free-vibration test. Our results provide a reference for improving estimates of the flexural rigidity of A. thaliana inflorescence stems.     

Cytoplasmic Location of α1A Voltage-Gated Calcium Channel C-Terminal Fragment (Cav2.1-CTF) Aggregate Is Sufficient to Cause Cell Death

The human α_1A voltage-dependent calcium channel (Ca_v2.1) is a pore-forming essential subunit embedded in the plasma membrane. Its cytoplasmic carboxyl(C)-tail contains a small poly-glutamine (Q) tract, whose length is normally 4∼19 Q, but when expanded up to 20∼33Q, the tract causes an autosomal-dominant neurodegenerative disorder, spinocerebellar ataxia type 6 (SCA6). A recent study has shown that a 75-kDa C-terminal fragment (CTF) containing the polyQ tract remains soluble in normal brains, but becomes insoluble mainly in the cytoplasm with additional localization to the nuclei of human SCA6 Purkinje cells. However, the mechanism by which the CTF aggregation leads to neurodegeneration is completely elusive, particularly whether the CTF exerts more toxicity in the nucleus or in the cytoplasm. We tagged recombinant (r)CTF with either nuclear-localization or nuclear-export signal, created doxycyclin-inducible rat pheochromocytoma (PC12) cell lines, and found that the CTF is more toxic in the cytoplasm than in the nucleus, the observations being more obvious with Q28 (disease range) than with Q13 (normal-length). Surprisingly, the CTF aggregates co-localized both with cAMP response element-binding protein (CREB) and phosphorylated-CREB (p-CREB) in the cytoplasm, and Western blot analysis showed that the quantity of CREB and p-CREB were both decreased in the nucleus when the rCTF formed aggregates in the cytoplasm. In human brains, polyQ aggregates also co-localized with CREB in the cytoplasm of SCA6 Purkinje cells, but not in other conditions. Collectively, the cytoplasmic Ca_v2.1-CTF aggregates are sufficient to cause cell death, and one of the pathogenic mechanisms may be abnormal CREB trafficking in the cytoplasm and reduced CREB and p-CREB levels in the nuclei.     

RNP2 of RNA Recognition Motif 1 Plays a Central Role in the Aberrant Modification of TDP-43

Phosphorylated and truncated TAR DNA-binding protein-43 (TDP-43) is a major component of ubiquitinated cytoplasmic inclusions in neuronal and glial cells of two TDP-43 proteinopathies, amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Modifications of TDP-43 are thus considered to play an important role in the pathogenesis of TDP-43 proteinopathies. However, both the initial cause of these abnormal modifications and the TDP-43 region responsible for its aggregation remain uncertain. Here we report that the 32 kDa C-terminal fragment of TDP-43, which lacks the RNP2 motif of RNA binding motif 1 (RRM1), formed aggregates in cultured cells, and that similar phenotypes were obtained when the RNP2 motif was either deleted from or mutated in full-length TDP-43. These aggregations were ubiquitinated, phosphorylated and truncated, and sequestered the 25 kDa C-terminal TDP-43 fragment seen in the neurons of TDP-43 proteinopathy patients. In addition, incubation with RNase decreased the solubility of TDP-43 in cell lysates. These findings suggest that the RNP2 motif of RRM1 plays a substantial role in pathological TDP-43 modifications and that it is possible that disruption of RNA binding may underlie the process of TDP-43 aggregation.     

Serum Uric Acid Is Associated with Left Ventricular Hypertrophy Independent of Serum Parathyroid Hormone in Male Cardiac Patients

Background

Several studies have shown that serum uric acid (UA) is associated with left ventricular (LV) hypertrophy. Serum levels of parathyroid hormone (PTH), which has bbe shown to be correlated with UA, is also known to be associated with cardiac hypertrophy; however, whether the association between UA and cardiac hypertrophy is independent of PTH remains unknown.

Purpose

We investigated whether the relationship between serum uric acid (UA) and LV hypertrophy is independent of intact PTH and other calcium-phosphate metabolism-related factors in cardiac patients.

Methods and Results

In a retrospective study, the association between UA and left ventricular mass index was assessed among 116 male cardiac patients (mean age 65±12 years) who were not taking UA lowering drugs. The median UA value was 5.9 mg/dL. Neither age nor body mass index differed significantly among the UA quartile groups. Patients with higher UA levels were more likely to be taking loop diuretics. UA showed a significant correlation with intact PTH (R = 0.34, P<0.001) but not with other calcium-phosphate metabolism-related factors. Linear regression analysis showed that log-transformed UA showed a significant association with left ventricular mass index, and this relationship was found to be significant exclusively in patients who were not taking loop and/or thiazide diuretics. Multivariate logistic regression analysis showed that log-transformed UA was independently associated with LV hypertrophy with an odds ratio of 2.79 (95% confidence interval 1.48–5.28, P = 0.002 per one standard deviation increase).

Conclusions

Among cardiac patients, serum UA was associated with LV hypertrophy, and this relationship was, at least in part, independent of intact PTH levels, which showed a significant correlation with UA in the same population.     

Chromone acyl glucosides and an ayanin glucoside from Dasiphora parvifolia

Two new chromone acyl glucosides, 5-hydroxy-7-O-(6-O-p-cis-coumaroyl-β-D-glucopyranosyl)-chromone (1) and 5-hydroxy-7-O-(6-O-p-trans-coumaroyl-β-D-glucopyranosyl)-chromone (2), and a new flavonoid glucoside, ayanin 3′-O-β-D-glucopyranoside (3) were isolated from aerial parts of Dasiphora parvifolia, together with flavonoid glycosides (4–10), catechins (11, 12), and hydrolysable tannins (13, 14). The chemical structures of these compounds were elucidated on the basis of spectroscopic data. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and the hyaluronidase inhibitory activity of these compounds were evaluated.     

The type of mutations induced by carbon-ion-beam irradiation of the filamentous fungus Neurospora crassa

Heavy-ion beams are known to cause great damage to cellular components and are particularly renowned for their ability to generate DNA double-strand breaks (DSBs). To gain insight into the mutagenic effect of carbon-ion beams and how such damage is repaired by the cell, Neurospora crassa mutants deficient in one of three components involved in the repair of DSBs, nonhomologous end-joining (NHEJ), homologous recombination repair (HR), and the Mre11-Rad50-Xrs2 (MRX) complex, were irradiated with a carbon-ion beam and killing effect, mutation frequencies, and the type of mutation incurred by survivors were analysed. The sensitivity of the NHEJ-deficient strain (mus-52) was higher than that of the wild-type and the HR-deficient (mei-3) strains at low doses of radiation, but was little changed as the level increased. As a result both the wild-type and HR-deficient strains were more sensitive than the NHEJ-deficient strain at high radiation levels. In addition, the frequency of forward mutation at the adenine-3 (ad-3) loci of the NHEJ-deficient mutant was lower than that of the wild-type strain at all levels, while the mutation frequency of the HR-deficient strain was consistently ∼3-fold higher than the wild-type. From the comparison of mutation type of each strain, deletions were frequently observed in wild-type strain, whilst base substitution and deletion in the mus-52 and mei-3 strains. These mutations resulting from carbon-ion-beam irradiation depend on the mechanism invoked to cope with DSBs. Furthermore, in wild-type cells, these mechanisms likely compete to repair DSBs.