ATP-driven reactions are required for the assembly of large stress granules

Stress granules (SGs) are functional messenger ribonucleoprotein aggregates, and their assembly is an important cellular process required for remodeling the signaling network to cope with extensive environmental stresses. SG formation is a stepwise process that involves the formation of a stable core followed by a less stable outer shell, and this process is often hampered by faulty regulation of protein phosphorylation. It remains unclear, however, which kinase activity is essential for SG formation. Here, we screened small molecule library of kinase inhibitors using a well-validated fluorogenic SG probe. Our screen, time-lapse microscopy, and biochemical analyses identified an ATP-mimetic SG inhibitor that selectively interferes with the fusion and growth, rather than the initial assembly, of SG core structures into the large assemblies. Thus, SGs utilize ATP-dependent chemical reactions to achieve their functional architectures.     

SPOP在机体发育中的作用

在胚胎发育中发挥重要作用的许多基因,其异常表达或突变常与疾病密切相关,斑点型BTB/POZ蛋白(speckle type BTB/POZ protein,SPOP)是其中之一。SPOP是E3泛素连接酶接头蛋白质,主要由MATH、BTB和BACK结构域构成,其功能正常发挥依赖于多个结构域各自不同的作用。SPOP主要通过泛素-蛋白酶体途径促进其靶蛋白质的降解来发挥作用。目前发现,SPOP底物蛋白质有30多种,其中大部分与前列腺癌、子宫内膜癌和肾癌的发生发展相关。SPOP在机体发育过程中也发挥重要作用,缺失或者突变SPOP导致小鼠出生后死亡。SPOP新生突变导致儿童神经发育障碍。SPOP调控机体发育也主要通过调控靶蛋白质降解来实现,包括作用于Gli2/3、PDX1、NANOG和SENP7等靶蛋白质来调控神经、骨骼和胰腺的发育以及衰老等过程。另有研究发现,SPOP与靶蛋白质会共定位到核斑(nuclear speckles)等无膜细胞器中,促进靶蛋白质的泛素化降解,并且SPOP寡聚体的形成以及其与底物多价互作引发的液-液相分离(liquid-liquid phase separation, LLPS)也在其中发挥了重要作用。SPOP寡聚化缺陷的BTB突变或BACK突变,可导致SPOP无法发生液-液相分离并定位于无膜细胞器。本文综合了最新研究进展,详细探讨了SPOP在机体发育过程中的重要作用。     

Physio-chemical properties of polymyxan 88A–water system

The system exopolysaccharide polymyxan 88A–water was studied at several temperatures. The temperature dependence of viscosity at cooling and heating was obtained in order to estimate the phase separation temperature (T_s) and the gelation temperature (T_g). The experimental values of T_s and T_g were used to plot the phase diagram of the system under study at polymer concentrations below 1.5 wt%. Viscous flow in the system was examined by the cylinder–cylinder rotation method. It has been found that: (i) at shear rates within 1–100 s⁻¹ the dependence of viscosity on shear rate can be fairly expressed by the power low; (ii) the activation enthalpy of viscous flow practically does not depend on shear rate; and (iii) the activation entropy of viscous flow is negative, most likely due to an orienting action of mechanical field.     

Phase Separation in Biology and Disease; Current Perspectives and Open Questions

In the past almost 15 years, we witnessed the birth of a new scientific field focused on the existence, formation, biological functions, and disease associations of membraneless bodies in cells, now referred to as biomolecular condensates. Pioneering studies from several laboratories [reviewed in1, 2, 3] supported a model wherein biomolecular condensates associated with diverse biological processes form through the process of phase separation. These and other findings that followed have revolutionized our understanding of how biomolecules are organized in space and time within cells to perform myriad biological functions, including cell fate determination, signal transduction, endocytosis, regulation of gene expression and protein translation, and regulation of RNA metabolism. Further, condensates formed through aberrant phase transitions have been associated with numerous human diseases, prominently including neurodegeneration and cancer. While in some cases, rigorous evidence supports links between formation of biomolecular condensates through phase separation and biological functions, in many others such links are less robustly supported, which has led to rightful scrutiny of the generality of the roles of phase separation in biology and disease.4, 5, 6, 7 During a week-long workshop in March 2022 at the Telluride Science Research Center (TSRC) in Telluride, Colorado, ～25 scientists addressed key questions surrounding the biomolecular condensates field. Herein, we present insights gained through these discussions, addressing topics including, roles of condensates in diverse biological processes and systems, and normal and disease cell states, their applications to synthetic biology, and the potential for therapeutically targeting biomolecular condensates.     

神经退行性疾病中的TDP-43蛋白聚集和相变

随着全球老龄化人口的急剧增加,神经退行性变已经成为危害公共健康的主要疾病.在神经退行性疾病(肌萎缩侧索硬化症(ALS)、额颞叶变性病(FTLD)和阿尔茨海默病(AD)等)患者脑组织中均能观察到蛋白质聚集形成的包涵体,其中TAR DNA结合蛋白43 (TDP-43)是主要成分之一.目前已发现多个TDP-43基因突变与家族...     

综述与专论：神经退行性疾病中的TDP-43蛋白聚集和相变

随着全球老龄化人口的急剧增加,神经退行性变已经成为危害公共健康的主要疾病。在神经退行性疾病(肌萎缩侧索硬化症(ALS)、额颞叶变性病(FTLD)和阿尔茨海默病(AD)等)患者脑组织中均能观察到蛋白质聚集形成的包涵体,其中TAR DNA结合蛋白43 (TDP-43)是主要成分之一。目前已发现多个TDP-43基因突变与家族性ALS密切相关。TDP-43属RNA/DNA结合蛋白,参与细胞内多种RNA代谢过程,它可以在细胞核和细胞质之间穿梭,通过相变诱导胞质和核质包涵体的形成。本文简要总结了TDP-43在体内和体外聚集以及发生相变的研究进展。理解TDP-43的异常相变将有助于寻找神经退行性疾病的潜在治疗靶点。     

长非编码RNA在相分离调控中的作用

相分离是细胞内生物分子由单一均相混合物形成2种不相溶的液滴凝聚体过程,是细胞内分子凝聚体和无膜细胞器形成的主要驱动力。相分离不仅在多种生理活动中发挥重要的动态调控作用,而且调控神经退行性疾病和癌症等多种疾病的发生发展。已有研究发现,长非编码RNA(lncRNA)与相分离密切相关,这为理解lncRNA的作用机制打开了新的视角,成为近年来非编码RNA领域的研究热点。本文重点介绍了LncRNA SLERT作为分子伴侣与DDX21蛋白相互作用,影响核仁纤维中心区/高密度纤维区(FC/DFCs)的相分离;LINC00657(NORAD)与PUM蛋白形成NP小体,驱动PUM蛋白的相分离而抑制其活性,促进基因组的稳定性;dilncRNA调控DNA损伤应答小RNAs (DDRNA)、p53结合蛋白1(53BP1)的相分离,lncRNA LINP1相分离液滴与Ku蛋白结合促进DNA损伤修复;LncRNA SNHG9、MELTF-AS1、MALR分别驱动LATS1、YBX1、ILF3蛋白质的相分离发挥促癌lncRNAs作用,GIRGL、LncFASA分别调控CAPRIN1、PRDX1的相分离在癌症发展中发挥抑癌基因作用;lncRNA XIST通过相分离驱动X染色体失活的研究。总之,本文综述了lncRNAs通过调节相分离在细胞核无膜细胞器的形成、基因组稳定性与DNA损伤修复、肿瘤发生发展和X染色体失活等病理生理过程中的最新研究进展。本文表明长非编码RNA可通过调节相分离,参与多种病理生理过程,有望为相分离介导的疾病的治疗提供新的方向。     

FRET analysis of domain formation and properties in complex membrane systems

The application of Förster Resonance Energy Transfer (FRET) to the detection and characterization of phase separation in lipid bilayers (both in model systems and in cell membranes) is reviewed. Models describing the rate and efficiency of FRET for both uniform probe distribution and phase separation, and recently reported methods for detection of membrane heterogeneity and determination of phase boundaries, probe partition coefficients and domain size, are presented and critically discussed. Selected recent applications of FRET to one-phase lipid systems, gel/fluid phase separation, liquid ordered/liquid disordered phase separation (lipid rafts), complex systems containing ceramide and cell membranes are presented to illustrate the wealth of information that can be inferred from carefully designed FRET studies of membrane domains.