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Biology subjects

Tan, R.

Publications and source records attributed to Tan, R..

4 recordsLinked to original sources

Microtubules Gate Tau Condensation to Spatially Regulate Microtubule Functions

Tau is an abundant microtubule-associated protein in neurons. Tau aggregation into insoluble fibrils is a hallmark of Alzheimers disease and other dementias, yet the physiological state of tau molecules within cells remains unclear. Using single molecule imaging, we directly observe that the microtubule lattice regulates reversible tau self-association, leading to dynamic condensation of tau molecules on the microtubule surface. Tau condensates form selectively permissible barriers, spatially regulating the activity of MT severing enzymes and the movement of molecular motors through their boundaries. We propose that reversible self-association of tau molecules, controlled by the microtubule, is an important mechanism of taus biological functions, and that oligomerization of tau is a common property shared between the physiological and disease forms of the molecule.\n\nOne Sentence SummaryReversible tau oligomerization regulates microtubule functions.

biophysics

Expression profile analysis of circular RNAs in essential hypertension by microarray and bioinformatics.

Circular RNAs (circRNAs), widely found in human cells, are involved in disease and play an important role in progression. To determine whether circRNAs are related in essential hypertension (EH), we analyzed the expression profile of circRNAs and miRNAs in 5 EH and 5 healthy controls cases which were screened by microarray. Through microarray data and public data analysis, differently expressed transcripts were divided into modules, and circRNAs were functionally annotated by miRNAs. The expression of two circRNAs, has_circ_0037909 and has_circ_0105015, were validated in EH by qRT-PCR, which may be associated with EH. Further analysis showed that two circRNAs might through immune system by up-regulation circRNAs and down-regulation expression. These circRNAs biological functions need to be further validated.

genetics

Planktonic interference and biofilm alliance between aggregation substance and endocarditis and biofilm associated pili in Enterococcus faecalis

Like many bacteria, Enterococcus faecalis encodes a number of adhesins involved in colonization or infection of different niches. Two well-studied E. faecalis adhesins, aggregation substance (AS) and endocarditis and biofilm-associated pili (Ebp), both contribute to biofilm formation on abiotic surfaces and in endocarditis, suggesting they may be expressed at the same time. Because different regulatory pathways have been reported for AS and Ebp, here we examined if they are co-expressed on the same cells and the functional impact of co-expression on individual cells and within a population. We found that while Ebp are only expressed on a subset of cells, when Ebp and AS are expressed on the same cells, pili interfere with AS-mediated clumping and impede AS-mediated conjugative plasmid transfer during planktonic growth. However, when the population density increases, horizontal gene transfer rates normalize and are no longer affected by pilus expression. Instead, at higher cell densities during biofilm formation, Ebp and AS differentially contribute to biofilm development and structure, synergizing to promote maximal biofilm formation.

microbiology

Cooperative Accumulation Of Dynein-Dynactin At Microtubule Minus-Ends Drives Microtubule Network Reorganization

SummaryCytoplasmic dynein-1 (dynein) is minus-end directed motor protein that transports cargo over long distances and organizes microtubules (MTs) during critical cellular processes such as mitotic spindle assembly. How dynein motor activity is harnessed for these diverse functions remains unknown. Here, we have uncovered a mechanism for how processive dynein-dynactin complexes drive MT-MT sliding, reorganization, and focusing, activities required for mitotic spindle assembly. We find that motors cooperatively accumulate, in limited numbers, at MT minus-ends. Minus-end accumulations drive MT-MT sliding, independent of MT orientation, and this activity always results in the clustering of MT minus-ends. At a mesoscale level, activated dynein-dynactin drives the formation and coalescence of MT asters. Macroscopically, dynein-dynactin activity leads to bulk contraction of millimeter-scale MT networks, demonstrating that minus-end accumulations produce network scale contractile stresses. Our data provides a model for how localized dynein activity is harnessed by cells to produce contractile stresses within the mitotic spindle.\n\nHighlightsO_LIProcessive dynein-dynactin complexes cooperatively form stable accumulations at MT minus-ends.\nC_LIO_LIMinus-end accumulations of motors slide MTs without orientation bias, leading to minus-end focusing.\nC_LIO_LIMinus-end accumulations of motors organize dynamic MTs into asters.\nC_LIO_LIMinus-end accumulations of motors drive bulk contractions of large-scale MT networks.\nC_LI

biophysics