分类: 生物学 >> 生物物理学 提交时间: 2016-05-12
摘要: Werner syndrome (WS) is a premature aging disorder caused by WRN protein deficiency. Here, we report on the generation of a human WS model in human embryonic stem cells (ESCs). Differentiation of WRN-null ESCs to mesenchymal stem cells (MSCs) recapitulates features of premature cellular aging, a global loss of H3K9me3, and changes in heterochromatin architecture. We show that WRN associates with heterochromatin proteins SUV39H1 and HP1 alpha and nuclear lamina-heterochromatin anchoring protein LAP2 beta. Targeted knock-in of catalytically inactive SUV39H1 in wild-type MSCs recapitulates accelerated cellular senescence, resembling WRN-deficient MSCs. Moreover, decrease in WRN and heterochromatin marks are detected in MSCs from older individuals. Our observations uncover a role for WRN in maintaining heterochromatin stability and highlight heterochromatin disorganization as a potential determinant of human aging.
分类: 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间: 2016-05-12
摘要: NLRP10 is a special member of NOD-like receptors (NLRs) family that lacks the leucine-rich repeats, suggesting that NLRP10 may act as an immunity regulator rather than directly receptor recognizing intracellular pathogen products. Previous studies on NLRP10 show that NLRP10 can interact with several components of NOD1 pathway thereby enhancing NOD1-mediated innate immune responses. In particular models, NLRP10 also negatively affects the activation of NLRP3 inflammasome. It has been proposed that NLRP10 oligomers interact with ASC to form a multi-protein platform for the recruitment of caspase-1 or other signaling components. Here, we show that pyrin-like domain (PYD) degradation induce the formation of NLRP10 oligomers, which present stick-shaped and circular structure. With the NLRP10 mutant G173A made by means of site-directed mutagenesis, we successfully obtain homogeneous full-length NLRP10 preparations. Corresponding gel filtration analysis and electron microscope (EM) data further proved that the PYD domain is important in protecting NLRP10 against aggregation.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-11
摘要: In plants, auxin signalling is initiated by the auxin-promoted interaction between the auxin receptor TIR1, an E3 ubiquitin ligase, and the Aux/IAA transcriptional repressors, which are subsequently degraded by the proteasome. Gain-of-function mutations in the highly conserved domain II of Aux/IAAs abolish the TIR1-Aux/IAA interaction and thus cause an auxin-resistant phenotype. Here we show that peptidyl-prolyl isomerization of rice OsIAA11 catalysed by LATERAL ROOTLESS2 (LRT2), a cyclophilin-type peptidyl-prolyl cis/trans isomerase, directly regulates the stability of OsIAA11. NMR spectroscopy reveals that LRT2 efficiently catalyses the cis/trans isomerization of OsIAA11. The lrt2 mutation reduces OsTIR1-OsIAA11 interaction and consequently causes the accumulation of a higher level of OsIAA11 protein. Moreover, knockdown of the OsIAA11 expression partially rescues the lrt2 mutant phenotype in lateral root development. Together, these results illustrate cyclophilin-catalysed peptidyl-prolyl isomerization promotes Aux/IAA degradation, as a mechanism regulating auxin signalling.