Reduction of thymosin beta4 and actin in HL60 cells during apoptosis is preceded by a decrease of their mRNAs

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Thymosin beta4 (Tbeta4) is a key G-actin sequestering peptide crucial for microfilament organization.
• Cellular microfilaments are disrupted during apoptosis.
• The role of Tbeta4 and actin in apoptosis induction requires further investigation.

Purpose of the Study:

• To investigate the changes in thymosin beta4 and actin content in HL60 cells following apoptosis induction by cytosine arabinoside (araC).
• To correlate these content changes with alterations in gene expression at the mRNA level.

Main Methods:

• HL60 cells were treated with cytosine arabinoside (araC) to induce apoptosis.
• Quantification of thymosin beta4 and total actin content was performed.
• Relative mRNA levels of thymosin beta4 and beta-actin were determined using ribonuclease protection assay (RPA).

Main Results:

• araC treatment led to a significant decrease in thymosin beta4 content to approximately 30% and total actin to 50% of control values after 48 hours.
• Total cellular protein and RNA content remained relatively constant.
• mRNA levels for both thymosin beta4 and beta-actin were significantly reduced, decreasing to 15% and 10% respectively after 48 hours of araC treatment.

Conclusions:

• Cytosine arabinoside (araC) significantly impacts thymosin beta4 and actin levels during apoptosis in HL60 cells.
• The observed changes in protein content are strongly correlated with reduced gene expression at the transcriptional level.
• These findings highlight the regulatory role of araC on thymosin beta4 and actin expression during cellular apoptosis.