Biogenesis and proteolytic processing of lysosomal DNase II

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Deoxyribonuclease II (DNase II) is essential for digesting DNA from apoptotic cells during phagocytosis.
• Understanding DNase II processing is key to elucidating its role in cellular DNA breakdown.

Purpose of the Study:

• To investigate the molecular properties and processing of mouse Deoxyribonuclease II (DNase II).
• To identify the cellular localization and activation mechanisms of DNase II.

Main Methods:

• Preparation of a polyclonal antibody against mouse DNase II.
• Partial purification using Con A Sepharose and Western blotting.
• Subcellular fractionation and analysis of DNase II in cathepsin L-deficient mice.

Main Results:

• Two endogenous forms of DNase II (30 kDa and 23 kDa) were detected, differing from the expected 45 kDa.
• These smaller DNase II forms were localized in lysosomes.
• DNase II processing was altered in mice lacking cathepsin L.
• Extracellular DNase II was detected as a pro-form, activated under acidic conditions.

Conclusions:

• DNase II undergoes processing and activation within lysosomes.
• Cathepsin L plays a significant role in the in vivo processing of DNase II.
• Lysosomal processing and activation are critical for DNase II function in DNA degradation.