Deletion of hypoxia-inducible factor prolyl 4-hydroxylase 2 in FoxD1-lineage mesenchymal cells leads to congenital truncal alopecia

Hypoxia-inducible factors (HIFs) induce numerous genes regulating oxygen homeostasis. As oxygen sensors of the cells, the HIF prolyl 4-hydroxylases (HIF-P4Hs) regulate the stability of HIFs in an oxygen-dependent manner. During hair follicle (HF) morphogenesis and cycling, the location of dermal papilla (DP) alternates between the dermis and hypodermis and results in varying oxygen levels for the DP cells. These cells are known to express hypoxia-inducible genes, but the role of the hypoxia response pathway in HF development and homeostasis has not been studied. Using conditional gene targeting and analysis of hair morphogenesis, we show here that lack of Hif-p4h-2 in Forkhead box D1 (FoxD1)-lineage mesodermal cells interferes with the normal HF development in mice. FoxD1-lineage cells were found to be mainly mesenchymal cells located in the dermis of truncal skin, including those cells composing the DP of HFs. We found that upon Hif-p4h-2 inactivation, HF development was disturbed during the first catagen leading to formation of epithelial-lined HF cysts filled by unorganized keratins, which eventually manifested as truncal alopecia. Furthermore, the depletion of Hif-p4h-2 led to HIF stabilization and dysregulation of multiple genes involved in keratin formation, HF differentiation, and HIF, transforming growth factor β (TGF-β), and Notch signaling. We hypothesize that the failure of HF cycling is likely to be mechanistically caused by disruption of the interplay of the HIF, TGF-β, and Notch pathways. In summary, we show here for the first time that HIF-P4H-2 function in FoxD1-lineage cells is essential for the normal development and homeostasis of HFs.     

Purification and characterization of Dolichos lablab lectin

The mannose/glucose-binding Dolichos lablab lectin (designated DLL) has been purified from seeds of Dolichos lablab (hyacinth bean) to electrophoretic homogeneity by affinity chromatography on an ovalbumin- Sepharose 4B column. The purified lectin gave a single symmetric protein peak with an apparent molecular mass of 67 kDa on gel filtration chromatography, and five bands ranging from 10 kDa to 22 kDa upon SDS-PAGE. N-Terminal sequence analysis of these bands revealed subunit heterogeneity due to posttranslational proteolytic truncation at different sites mostly at the carboxyl terminus. The carbohydrate binding properties of the purified lectin were investigated by three different approaches: hemagglutination inhibition assay, quantitative precipitation inhibition assay, and ELISA. On the basis of these studies, it is concluded that the Dolichos lablab lectin has neither an extended carbohydrate combining site, nor a hydrophobic binding site adjacent to it. The carbohydrate combining site of DLL appears to most effectively accommodate a nonreducing terminal alpha-d-mannosyl unit, and to be complementary to the C-3, C-4, and C-6 equatorial hydroxyl groups of alpha-d-mannopyranosyl and alpha-d-glucopyranosyl residues. DLL strongly precipitates murine IgM but not IgG, and the recent finding that this lectin interacts specifically with NIH 3T3 fibroblasts transfected with the Flt3 tyrosine kinase receptor and preserves human cord blood stem cells and progenitors in a quiescent state for prolonged periods in culture, make this lectin a valuable tool in biomedical research.      

不同胁迫预处理提高水稻幼苗抗寒性期间蛋白质的变化

水稻(Oryza sativa L.)幼苗经盐、热激和冷三种不同胁迫预处理均提高了幼苗的抗寒性。与未预处理苗相比,在处理后、低温伤害后和常温下恢复2d的三个时期,不同胁迫预处理苗的可溶性和热不稳定蛋白含量变化趋势甚为相似,但热稳定蛋白含量变化则各有异同。SDS-PAGE图谱分析显示,不同胁迫预处理提高水稻幼苗抗寒性时,其可溶性蛋白、热稳定和热不稳定蛋白组成变化亦各有异同。除诱导出共有的新多肽外,还各自诱导出特有的新多肽。结果表明,植物对不同胁迫的交叉适应存在一定的共同机理,但亦可看出植物对同一种环境胁迫似乎不是以同一的机理去适应。     

Impairment of <Emphasis Type="Italic">Wnt11</Emphasis> function leads to kidney tubular abnormalities and secondary glomerular cystogenesis

Background

Wnt11 is a member of the Wnt family of secreted signals controlling the early steps in ureteric bud (UB) branching. Due to the reported lethality of Wnt11 knockout embryos in utero, its role in later mammalian kidney organogenesis remains open. The presence of Wnt11 in the emerging tubular system suggests that it may have certain roles later in the development of the epithelial ductal system.

Results

The Wnt11 knockout allele was backcrossed with the C57Bl6 strain for several generations to address possible differences in penetrance of the kidney phenotypes. Strikingly, around one third of the null mice with this inbred background survived to the postnatal stages. Many of them also reached adulthood, but urine and plasma analyses pointed out to compromised kidney function. Consistent with these data the tubules of the C57Bl6 Wnt11 ^?/? mice appeared to be enlarged, and the optical projection tomography indicated changes in tubular convolution. Moreover, the C57Bl6 Wnt11 ^?/? mice developed secondary glomerular cysts not observed in the controls. The failure of Wnt11 signaling reduced the expression of several genes implicated in kidney development, such as Wnt9b, Six2, Foxd1 and Hox10. Also Dvl2, an important PCP pathway component, was downregulated by more than 90 % due to Wnt11 deficiency in both the E16.5 and NB kidneys. Since all these genes take part in the control of UB, nephron and stromal progenitor cell differentiation, their disrupted expression may contribute to the observed anomalies in the kidney tubular system caused by Wnt11 deficiency.

Conclusions

The Wnt11 signal has roles at the later stages of kidney development, namely in coordinating the development of the tubular system. The C57Bl6 Wnt11 ^?/? mouse generated here provides a model for studying the mechanisms behind tubular anomalies and glomerular cyst formation.

     

Mitochondrial 2,4-dienoyl-CoA Reductase Deficiency in Mice Results in Severe Hypoglycemia with Stress Intolerance and Unimpaired Ketogenesis

The mitochondrial β-oxidation system is one of the central metabolic pathways of energy metabolism in mammals. Enzyme defects in this pathway cause fatty acid oxidation disorders. To elucidate the role of 2,4-dienoyl-CoA reductase (DECR) as an auxiliary enzyme in the mitochondrial β-oxidation of unsaturated fatty acids, we created a DECR–deficient mouse line. In Decr^−/− mice, the mitochondrial β-oxidation of unsaturated fatty acids with double bonds is expected to halt at the level of trans-2, cis/trans-4-dienoyl-CoA intermediates. In line with this expectation, fasted Decr^−/− mice displayed increased serum acylcarnitines, especially decadienoylcarnitine, a product of the incomplete oxidation of linoleic acid (C_18:2), urinary excretion of unsaturated dicarboxylic acids, and hepatic steatosis, wherein unsaturated fatty acids accumulate in liver triacylglycerols. Metabolically challenged Decr^−/− mice turned on ketogenesis, but unexpectedly developed hypoglycemia. Induced expression of peroxisomal β-oxidation and microsomal ω-oxidation enzymes reflect the increased lipid load, whereas reduced mRNA levels of PGC-1α and CREB, as well as enzymes in the gluconeogenetic pathway, can contribute to stress-induced hypoglycemia. Furthermore, the thermogenic response was perturbed, as demonstrated by intolerance to acute cold exposure. This study highlights the necessity of DECR and the breakdown of unsaturated fatty acids in the transition of intermediary metabolism from the fed to the fasted state.     

Characterization of 2-enoyl thioester reductase from mammals. An ortholog of YBR026p/MRF1'p of the yeast mitochondrial fatty acid synthesis type II

A data base search with YBR026c/MRF1', which encodes trans-2-enoyl thioester reductase of the intramitochondrial fatty acid synthesis (FAS) type II in yeast (Torkko, J. M., Koivuranta, K. T., Miinalainen, I. J., Yagi, A. I., Schmitz, W., Kastaniotis, A. J., Airenne, T. T., Gurvitz, A., and Hiltunen, K. J. (2001) Mol. Cell. Biol. 21, 6243-6253), revealed the clone AA393871 (HsNrbf-1, nuclear receptor binding factor 1) in human EST data bank. Expression of HsNrbf-1, tagged C-terminally with green fluorescent protein, in HeLa cells, resulted in a punctated fluorescence signal, superimposable with the MitoTracker Red dye. Wild-type polypeptide was immunoisolated from the extract of bovine heart mitochondria. Recombinant HsNrbf-1p reduces trans-2-enoyl-CoA to acyl-CoA with chain length from C6 to C16 in an NADPH-dependent manner with preference to medium chain length substrate. Furthermore, expression of HsNRBF-1 in the ybr026cDelta yeast strain restored mitochondrial respiratory function allowing growth on glycerol. These findings provide evidence that Nrbf-1ps act as a mitochondrial 2-enoyl thioester reductase, and mammalian cells may possess bacterial type fatty acid synthetase (FAS type II) in mitochondria, in addition to FAS type I in the cytoplasm.     

An attempt to estimate the predatory pressure exerted by the lesser weever, Trachinus vipera Cuvier, in the southern North Sea

In order to evaluate the impact of the lesser weever on the ecosystem of the southern North Sea, geographical distribution, density, growth, production and food requirements have been estimated. High densities were found on and around the Brown Ridge, an area with high tidal current velocities, medium grain-size of the sediment and a poor benthic fauna. Growth is restricted to the months of June October. During the winter cessation of growth a considerable loss of weight (about 20%) takes place. Mortality has been estimated by using the average size frequency distribution of all catches made from 1972 to 1984. The resulting convex type of survival curve indicates a high survival rate of the II to IV-group fishes. The production (estimated with Allen's graphical method) of a population of 100 individuals including all age groups (0-VI) amounts to 123.7 g AFDW-year'. In areas with highest densities, consequently, production amounts to 0.018–0.078 g AFDW-m² -year^-1. With an assumed transfer efficiency of 10% through the year, food requirements amounts to 0.18–0.78 g AFDW-m ² -year ^-1. Since the lesser weever feeds mainly on fish (85.6%), almost exclusively on gobies (Pomatoschistus sp.), and with an assumed transfer efficiency of approximately 10%, the indirect predatory pressure exerted by it may amount to 1.6 6.7g AFDW-m ².year ^-1. A possible feeding by gobies on pelagic organisms (calanoids, mysids) is discussed.