Yinghua Guan

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The primary cilium acts as a transducer of extracellular stimuli into intracellular signaling [1, 2]. Its regulation, particularly with respect to length, has been defined primarily by genetic experiments and human disease states in which molecular components that are necessary for its proper construction have been mutated or deleted [1]. However, dynamic(More)
Excluding 53BP1 from chromatin is required to attenuate the DNA damage response during mitosis, yet the functional relevance and regulation of this exclusion are unclear. Here we show that 53BP1 is phosphorylated during mitosis on two residues, T1609 and S1618, located in its well-conserved ubiquitination-dependent recruitment (UDR) motif. Phosphorylating(More)
Expansions of preexisting polyglutamine (polyQ) tracts in at least nine different proteins cause devastating neurodegenerative diseases. There are many unique features to these pathologies, but there must also be unifying mechanisms underlying polyQ toxicity. Using a polyQ-expanded fragment of huntingtin exon-1 (Htt103Q), the causal protein in Huntington(More)
Homo-oligomerization is found in many biological systems and has been extensively studied in vitro. However, our ability to quantify and understand oligomerization processes in cells is still limited. We used fluorescence correlation spectroscopy and mathematical modeling to measure the dynamics of the tetramers formed by the tumor suppressor protein p53 in(More)
Chemical gradients can generate pattern formation in biological systems. In the fission yeast Schizosaccharomyces pombe, a cortical gradient of pom1p (a DYRK-type protein kinase) functions to position sites of cytokinesis and cell polarity and to control cell length. Here, using quantitative imaging, fluorescence correlation spectroscopy, and mathematical(More)
Recruitment of 53BP1 to chromatin flanking double strand breaks (DSBs) requires γH2AX/MDC1/RNF8-dependent ubiquitination of chromatin and interaction of 53BP1 with histone H4 methylated on lysine 20 (H4K20me). Several histone methyltransferases have been implicated in 53BP1 recruitment, but their quantitative contributions to the 53BP1 response are unclear.(More)
Leukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We(More)
The microtubule-targeting maytansinoids accumulate in cells and induce mitotic arrest at 250- to 1000-fold lower concentrations than those required for their association with tubulin or microtubules. To identify the mechanisms of this intracellular accumulation and exceptional cytotoxicity of maytansinoids we studied interaction of a highly cytotoxic(More)
MjHsp16.5 was separately labeled by fluorescent dye Cy3 and Cy5.5. The dissociation event of a single 24-mer MjHsp16.5 molecule was captured by single-molecule imaging (SMI). Temperature-regulated subunit exchange was revealed by the real-time fluorescence resonance energy transfer (FRET). The combination of single-molecular statistics and kinetic(More)
The heterogeneous motion of alpha(1B)-adrenoceptor (alpha(1B)-AR) was visualized in living cells with BODIPY-labeled antagonist of AR by single molecule fluorescence microscopy at high spatial resolution. The moving trajectory was reconstructed by precise localization (better than 20 nm) with a least-square fit of a two-dimensional Gaussian point spread(More)