Project description:BACKGROUND:All known mechanisms of apoptosis induced by resveratrol act through cell cycle arrest and changes in mitochondrial membrane potential. It is currently unknown whether resveratrol-induced apoptosis is associated with other physiological processes, such as autophagy. METHODS:Apoptosis-related markers involved in the intrinsic and extrinsic apoptotic pathways, and autophagic markers were detected by using western blotting and immunofluorescence. Mitochondrial membrane potential was assayed by flow cytometry. Pharmaceutical or genetic inhibition of autophagy involved were carried by 3- methyladenine or knockdown of autophagy-related (Atg) genes by siRNA. Differences between two values were tested by Student's unpaired t test. RESULTS:We show that resveratrol-induced apoptosis occurs through both the intrinsic and extrinsic apoptotic pathways. Mitochondrial membrane potential and apoptosis-related markers, such as an increased Bax/Bcl-2 ratio, and cleaved forms of caspase-8 and caspase-3, arise following resveratrol addition. Moreover, we find that resveratrol increases both the levels of microtubule-associated protein 1 light chain 3-II and the number of autophagosomes, and further demonstrate that resveratrol-induced autophagy depends on the LKB1-AMPK-mTOR pathway. We next reveal that some apoptosis-related markers induced by resveratrol are further attenuated by the inhibition of autophagy with 3-methyladenine or knockdown of autophagy-related (Atg) genes by siRNA. CONCLUSIONS:These results suggest that resveratrol induced apoptotic cell death of HL-60 cells depends on the autophagy activated through both the LKB1-AMPK and PI3K/AKT-regulated mTOR signaling pathways.
Project description:2×10^7 HL60 cells were treated with 10 uM ATRA for 2 and 5 days, and conducted Hi-C to study the chromosomal architecture. Cells were fixed by 1% formaldehyde (v/v) for 15 min at room temperature (RT) with slowly rotation. Cells were lysed by 550 μl lysis buffer (500 μl 10 mM Tris-HCl pH 8.0, 10 mM NaCl, 0.2% Igepal CA-630 and 50 μl protease inhibitors) using a homogenizer, and harvested the chromatin at 5,000 rpm and washed twice. The pellet was added 1% SDS and incubated at 65 oC for 10 min, then quenched by Triton X-100. The chromatin was digested by 600 U MboI (NEB, Ipswich, USA) at 37 oC overnight. The next day, enzymes were inactivated by 10% SDS at 65 oC for 30 min, and the restriction fragment overhangs were filled in using biotin-14-dCTP and Klenow at 37 oC for 45 min, and the ligation was conducted in 7.61 ml ligation mix (745 μl 10% Triton X-100, 745 μl 10x ligation buffer (500 mM Tris-HCl pH 7.5, 100 mM MgCl2, 100 mM DTT), 80 μl 10 mg/ml BSA, 80 μl 100 mM ATP and 5.96 ml water) for 4 h at 16°C. The blunt-end Hi-C ligation was sonicated and pull down by streptavidin beads, then purified by ethanol. Hi-C library was prepared for paired ending sequencing using NEBNext® UltraTM DNA Library Prep Kit for Illuina® (NEB). For regular 3C ligation, after enzymes inactivation, 10 μl 1 U/μl T4 DNA ligase was added to incubate at 16°C overnight. The interaction was detected by qPCR using the specific 3C primers (Table 1) followed by DNA purification. Hi-C was conducted in PE-150. An iterative method for Hi-C mapping with initial length 30bp, if it fails to map uniquely, the next round of mapping for additional 20 bp continued, this procedure lasts until the full read length reaches 150bp. The Hi-C reads were mapped to the human reference genome (assembly GRCh38) using bowtie2 (v2.2.9). The reads mapped to the same restriction fragment, the reads less than 500bp and PCR duplicates were all removed. Hi-C contact maps were normalized using ICE.
Project description:Morphological identification is a widespread procedure to assess the presence of apoptosis by visual inspection of the morphological characteristics or the fluorescence images. The procedure is lengthy and results are observer dependent. A quantitative automatic analysis is objective and would greatly help the routine work. We developed an image processing and segmentation method which combined the Otsu thresholding and morphological operators for apoptosis study. An automatic determination method of apoptotic stages of HL-60 cells with fluorescence images was developed. Comparison was made between normal cells, early apoptotic cells and late apoptotic cells about their geometric parameters which were defined to describe the features of cell morphology. The results demonstrated that the parameters we chose are very representative of the morphological characteristics of apoptotic cells. Significant differences exist between the cells in different stages, and automatic quantification of the differences can be achieved.
Project description:The human leukemia cell line (HL-60) is an alternative to primary neutrophils in research studies. However, because HL-60 cells proliferate in an incompletely differentiated state, they must undergo differentiation before they acquire the functional properties of neutrophils. Here we provide evidence of swarming and chemotaxis in differentiated HL-60 neutrophil-like cells (dHL-60) using precise microfluidic assays. We found that dimethyl sulfoxide differentiated HL-60 cells (DdHL-60) have a larger size, increased length, and lower ability to squeeze through narrow channels compared to primary neutrophils. They migrate through tapered microfluidic channels slower than primary neutrophils, but faster than HL-60s differentiated by other protocols, e.g., using all-trans retinoic acid. We found that dHL-60 can swarm toward zymosan particle clusters, though they display disorganized migratory patterns and produce swarms of smaller size compared to primary neutrophils.
Project description:Cell migration plays an essential role in wound healing and inflammatory processes inside the human body. Peripheral blood neutrophils, a type of polymorphonuclear leukocyte (PMN), are the first cells to be activated during inflammation and subsequently migrate toward an injured tissue or infection site. This response is dependent on both biochemical signaling and the extracellular environment, one aspect of which includes increased temperature in the tissues surrounding the inflammation site. In our study, we analyzed temperature-dependent neutrophil migration using differentiated HL-60 cells. The migration speed of differentiated HL-60 cells was found to correlate positively with temperature from 30 to 42 °C, with higher temperatures inducing a concomitant increase in cell detachment. The migration persistence time of differentiated HL-60 cells was higher at lower temperatures (30-33 °C), while the migration persistence length stayed constant throughout the temperature range. Coupled with the increased speed observed at high temperatures, this suggests that neutrophils are primed to migrate more effectively at the elevated temperatures characteristic of inflammation. Temperature gradients exist on both cell and tissue scales. Taking this into consideration, we also investigated the ability of differentiated HL-60 cells to sense and react to the presence of temperature gradients, a process known as thermotaxis. Using a two-dimensional temperature gradient chamber with a range of 27-43 °C, we observed a migration bias parallel to the gradient, resulting in both positive and negative thermotaxis. To better mimic the extracellular matrix (ECM) environment in vivo, a three-dimensional collagen temperature gradient chamber was constructed, allowing observation of biased neutrophil-like differentiated HL-60 migration toward the heat source.
Project description:KN-62, an inhibitor of the calmodulin-dependent protein kinases (CaMKs), enhances the terminal differentiation of retinoic acid sensitive human myeloid leukemia cell lines. In an effort to identify additional CaMK inhibitors that exhibit more potent activity in triggering leukemia cell differentiation, we synthesized 45 analogues of KN-62 and determined their ability to induce HL-60 cell differentiation. Sixteen of these novel analogues exhibited significant differentiation-inducing activity, and one analogue, AS-004, was five times more potent than KN-62 in inhibiting proliferation and inducing differentiation of HL-60 cells. Such KN-62 analogues and/or related compounds may prove useful in treating promyelocytic leukemia.
Project description:Epichromatin, the surface of chromatin facing the nuclear envelope in an interphase nucleus, reveals a "rim" staining pattern with specific mouse monoclonal antibodies against histone H2A/H2B/DNA and phosphatidylserine epitopes. Employing a modified ChIP-Seq procedure on undifferentiated and differentiated human leukemic (HL-60/S4) cells,>95% of assembled epichromatin regions overlapped with Alu retrotransposons. They also exhibited enrichment of the AluS subfamily and of Alu oligomers. Furthermore, mapping epichromatin regions to the human chromosomes revealed highly similar localization patterns in the various cell states and with the different antibodies. Comparisons with available epigenetic databases suggested that epichromatin is neither "classical" heterochromatin nor highly expressing genes, implying another function at the surface of interphase chromatin. A modified chromatin immunoprecipitation procedure (xxChIP) was developed because the studied antibodies react generally with mononucleosomes and lysed chromatin. A second fixation is necessary to securely attach the antibodies to the epichromatin epitopes of the intact nucleus.
Project description:RNA Evaluation HL-60 derived M1 macrophages (differentiated 12hr) microRNA-seq from Mortazavi For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODE_Data_Use_Policy_for_External_Users_03-07-14.pdf