Studies on membrane-bound renin in the mouse and rat

Area of Science:

• Biochemistry
• Endocrinology
• Molecular Biology

Background:

• Renin, a key enzyme in the renin-angiotensin system, is primarily known for its role in blood pressure regulation.
• Membrane-bound forms of renin have been identified, but their specific functions and regulation are less understood.
• The submaxillary gland is a known site of renin production, particularly in response to hormonal stimuli.

Purpose of the Study:

• To isolate and characterize membrane-bound renin from mouse and rat tissues.
• To investigate the effect of male sex hormones and anabolic steroids on renin activity in the female mouse submaxillary gland.
• To explore methods for activating and isolating microsomal renin and kallikrein.

Main Methods:

• Isolation of membrane-bound renin from submaxillary gland and kidney tissues of mice and rats.
• Administration of testosterone and nandrolone phenpropionate to female mice to induce renin activity.
• Use of Actinomycin D to assess the role of gene transcription in renin induction.
• Density gradient centrifugation and N2 cavitation techniques for isolating microsomal renin.
• Activation of partially active microsomal renin using freezing/thawing or Triton X-100.

Main Results:

• Membrane-bound renin was successfully isolated from mouse and rat kidneys and mouse submaxillary glands.
• Testosterone and nandrolone phenpropionate significantly induced renin activity in the microsomal fraction of female mouse submaxillary glands.
• Actinomycin D partially inhibited this hormone-induced renin activity.
• Microsomal renin isolation was achieved using density gradient centrifugation and N2 cavitation.
• Freezing/thawing and Triton X-100 were effective in activating partially active microsomal renin.
• The same microsomal fraction contained active kallikrein, and a plasma membrane-enriched fraction showed both renin and kallikrein activity.

Conclusions:

• Male sex hormones can induce renin activity in the female mouse submaxillary gland, suggesting hormonal regulation of this enzyme.
• Membrane-bound renin can be isolated from kidney and submaxillary gland tissues using various biochemical techniques.
• Microsomal renin activity can be enhanced through specific activation methods.
• Co-localization of renin and kallikrein in specific cellular fractions suggests potential functional interactions.