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cDNA cloning of human myeloperoxidase: decrease in myeloperoxidase mRNA upon induction of HL-60 cells
Abstract:
Myeloperoxidase (MPO), the most abundant neutrophil protein, is a bacteriocidal component of the primary granules and a critical marker in distinguishing acute myelogenous leukemia from acute lymphoid leukemia. A cDNA clone for human MPO was isolated by immunologic screening of human hematopoietic lambda gt11 expression vector libraries with specific anti-MPO antibody. The identity of the cDNA clone was confirmed by finding that epitope-selected antibody against this clone recognizes purified MPO and MPO in human promyelocytic (HL-60) cell lysates by immunoblot analysis, and that hybrid selection of HL-60 mRNA with this cDNA clone and translation in vitro results in the synthesis of an 80-kDa protein recognized by the anti-MPO antiserum. RNA blot analysis with this MPO cDNA clone detects hybridization to two polyadenylylated transcripts of approximately 3.6 and approximately 2.9 kilobases in HL-60 cells. No hybridization is detected to human placenta mRNA. Upon induction of HL-60 cells to differentiate by incubation for 4 days with dimethyl sulfoxide, a drastic decrease in the hybridization intensity of these two bands is seen. This is consistent with previous data suggesting a decrease in MPO synthesis upon such induction of these cells. The MPO cDNA should be useful for further molecular and genetic characterization of MPO and its expression and biosynthesis in normal and leukemic granulocytic differentiation.
Insights
Researchers isolated a human myeloperoxidase (MPO) cDNA clone, crucial for distinguishing leukemia types. This clone aids in studying MPO
Area of Science:
- Molecular Biology
- Hematology
- Cancer Research
Background:
- Myeloperoxidase (MPO) is a key neutrophil protein involved in bacterial killing.
- MPO serves as a critical diagnostic marker for differentiating acute myelogenous leukemia (AML) from acute lymphoid leukemia (ALL).
- Understanding MPO gene expression is vital for granulocytic differentiation studies.
Purpose of the Study:
- To isolate and confirm a complementary DNA (cDNA) clone for human MPO.
- To analyze MPO gene expression in human promyelocytic leukemia (HL-60) cells.
- To investigate the regulation of MPO synthesis during cellular differentiation.
Main Methods:
- Immunologic screening of human hematopoietic expression vector libraries using anti-MPO antibody.
- Confirmation of cDNA identity via immunoblot analysis and hybrid selection with HL-60 mRNA.
- RNA blot analysis to detect MPO transcripts in HL-60 cells and assess changes upon differentiation induction.
Main Results:
- A human MPO cDNA clone was successfully isolated and its identity confirmed.
- Two MPO transcripts (approximately 3.6 and 2.9 kilobases) were detected in HL-60 cells.
- Dimethyl sulfoxide-induced differentiation of HL-60 cells led to a significant decrease in MPO transcript levels.
Conclusions:
- The isolated MPO cDNA clone is a valuable tool for molecular and genetic studies.
- MPO expression is regulated during granulocytic differentiation, with decreased synthesis observed upon HL-60 cell differentiation.
- This research provides a foundation for further characterization of MPO in normal and leukemic hematopoiesis.