Related Experiment Videos
Characterization of a differentiation-inhibitory activity from nondifferentiating mouse myeloid leukemia cells
Abstract:
Mouse myeloid leukemic M1 cells are induced to differentiate by various differentiation inducers. Activity for inhibition of induction of differentiation of M1 cells (I-activity) has been found in conditioned medium of variant M1 cell clones resistant to differentiation inducers, and this I-activity has been shown to be closely associated with resistance of the cells to differentiation inducers. In this work, the I-activity in the conditioned medium of the resistant M1 cells was shown to bind to Carboxymethyl-Sepharose CL-6B and to be eluted with 0.27-0.4 M NaCl. The profile of gel filtration of I-activity from Sephadex G-200 indicated considerable heterogeneity in molecules with I-activity; the apparent molecular range of the main I-activity was 60,000-80,000. On chromatofocusing, the I-activity was eluted with Polybuffer 96-acetic acid at pH 8.8-9.0. The I-activity was inactivated by treatment with trypsin or by heating at 75 degrees C for 30 min. Therefore, the main I-activity seemed to be due to a basic protein(s).
Insights
Researchers identified an inhibitor of M1 cell differentiation (I-activity) in resistant cell lines. This I-activity, associated with differentiation resistance, appears to be a basic protein.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Mouse myeloid leukemic M1 cells differentiate upon induction.
- Resistant M1 cell clones exhibit an inhibitory activity (I-activity) in their conditioned medium.
- This I-activity is linked to resistance against differentiation inducers.
Purpose of the Study:
- To characterize the biochemical properties of the I-activity found in resistant M1 cell conditioned medium.
- To investigate the nature of the molecule responsible for inhibiting M1 cell differentiation.
Main Methods:
- Affinity chromatography using Carboxymethyl-Sepharose CL-6B.
- Gel filtration chromatography with Sephadex G-200.
- Ion-exchange chromatography (chromatofocusing) with Polybuffer 96-acetic acid.
- Enzymatic (trypsin) and thermal inactivation assays.
Main Results:
- I-activity bound to Carboxymethyl-Sepharose and eluted with 0.27-0.4 M NaCl.
- Gel filtration revealed molecular heterogeneity, with the main I-activity in the 60,000-80,000 molecular weight range.
- Chromatofocusing indicated elution at pH 8.8-9.0.
- I-activity was inactivated by trypsin treatment and heating to 75°C for 30 minutes.
Conclusions:
- The I-activity inhibiting M1 cell differentiation is likely a basic protein.
- These findings provide insights into the molecular mechanisms underlying resistance to differentiation inducers in leukemic cells.