4 research outputs found
Nuclei concentration.
<p>Calculated profiles of nuclei concentrations (pM) versus length (nm), or equivalently time scale, as a function of the bin size. 2 monomers/bin corresponds to 0.47 nm/bin, while 20 monomers/bin corresponds to 4.7 nm/bin.</p
Equations and variables.
<p>Set of equations used to estimate the total number of insulin nuclei, <i>N<sub>n,t</sub></i>, from the available fibril length distribution. The number of measured fibrils per i-th bin, <i>N<sub>fi</sub></i>, Eqs. (1) & (3), were calculated using the Weibull distribution (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020072#pone-0020072-g001" target="_blank"><b>Figure 1</b></a>). From the definition of the nucleus, the total number of fibrils, <i>N<sub>f,t</sub></i>, is equivalent to the total number of nuclei, <i>N<sub>n,t</sub></i>, Eq. (4). A description and the units are provided for each variable.</p
Fibril length distribution.
<p>The histogram of frequency versus fibril length summarizes AFM data for 495 insulin fibrils in 36.6 nm/bin for a total of 100 bins. The parameters of this distribution were estimated using distribution-fitting software, EasyFit (MathWave Technologies). The software fitted the data using 60 different distributions and ranked the results based on three different goodness-of-fit tests. The histogram shows the best fit (Kolmogorov-Smirnov statistic, <i>D</i> = 0.0187, Anderson-Darling, <i>A<sup>2</sup></i> = 0.323, and Chi-Squared, <i>χ<sup>2</sup></i> = 5.113) using the Weibull distribution (line). The probability density function is with values of the parameters: α = 1.7409 and β = 1248.5. (A) Example of a 2D AFM image of insulin fibrils, with measurements: A free-hand curve was drawn on the fibril and two cursors placed at each fibril end. Measurements are in nm. (B) Example of a 3D image, which assisted in detecting individual fibrils.</p
A Potent and Selective Quinoxalinone-Based STK33 Inhibitor Does Not Show Synthetic Lethality in KRAS-Dependent Cells
The KRAS oncogene is found in up to 30% of all human
tumors. In
2009, RNAi experiments revealed that lowering mRNA levels of a transcript
encoding the serine/threonine kinase STK33 was selectively toxic to
KRAS-dependent cancer cell lines, suggesting that small-molecule inhibitors
of STK33 might selectively target KRAS-dependent cancers. To test
this hypothesis, we initiated a high-throughput screen using compounds
in the Molecular Libraries Small Molecule Repository (MLSMR). Several
hits were identified, and one of these, a quinoxalinone derivative,
was optimized. Extensive SAR studies were performed and led to the
chemical probe ML281 that showed low nanomolar inhibition of purified
recombinant STK33 and a distinct selectivity profile as compared to
other STK33 inhibitors that were reported in the course of these studies.
Even at the highest concentration tested (10 μM), ML281 had
no effect on the viability of KRAS-dependent cancer cells. These results
are consistent with other recent reports using small-molecule STK33
inhibitors. Small molecules having different chemical structures and
kinase-selectivity profiles are needed to fully understand the role
of STK33 in KRAS-dependent cancers. In this regard, ML281 is a valuable
addition to small-molecule probes of STK33