Cathepsin D in prawn reproductive system: its localization and function in actin degradation

Area of Science:

• Reproductive biology
• Enzymology
• Crustacean physiology

Background:

• Cathepsin D (CAT-D) is a lysosomal protease with variable expression in reproductive tissues.
• Its role in invertebrate reproduction is not well-defined.

Purpose of the Study:

• To investigate the presence, localization, and function of Cathepsin D (MrCAT-D) in the reproductive system of the shrimp Macrobrachium rosenbergii.
• To explore the potential role of MrCAT-D in sperm development and release.

Main Methods:

• Localization of MrCAT-D transcript and protein in shrimp testes using immunohistochemistry and Western blotting.
• Enzymatic activity assays using a specific fluorogenic substrate.
• Investigation of MrCAT-D's substrate specificity, including filamentous actin hydrolysis.

Main Results:

• MrCAT-D was detected in both somatic (Sertoli-like) and germ cells within the M. rosenbergii testis.
• The enzyme was localized to the sperm surface, not the acrosome.
• Active MrCAT-D demonstrated enzymatic activity, including the hydrolysis of filamentous actin found at germ cell junctions.

Conclusions:

• MrCAT-D is present and enzymatically active in the reproductive tract of M. rosenbergii.
• Its actin-degrading function suggests a role in facilitating sperm release from the testicular epithelium.
• This finding contributes to understanding the molecular mechanisms of reproduction in crustaceans.