A simple method for the specific detection of Ren-1 renin.

Area of Science:

• Renal physiology
• Histochemistry
• Biochemistry

Background:

• Renin, a key enzyme in the renin-angiotensin system, exists as Ren-1 and Ren-2 isoforms in mice.
• Ren-1 and Ren-2 are expressed in mouse kidneys, with Ren-1 also found in the submandibular gland.
• Accurate detection methods are crucial for studying renin's role in physiological processes.

Purpose of the Study:

• To evaluate the efficacy of a modified periodic acid silver-methenamine (PAM) staining technique for specifically detecting Ren-1 renin.
• To compare the specificity of this modified PAM staining with conventional immunohistochemistry.

Main Methods:

• Paraffin-embedded kidney and submandibular gland sections from various mouse strains, rats, and a human were prepared.
• Sections were stained using PAM, with reactions optimized for weak intensity (W-PAM).
• Immunohistochemistry and analysis of angiotensin II type 1a receptor gene knockout (AT1aKO) mice were used for validation.

Main Results:

• Weak PAM (W-PAM) staining demonstrated high specificity for juxtaglomerular (JG) cells in all mouse strains examined.
• Immunohistochemistry and AT1aKO mouse data confirmed that W-PAM specifically detects Ren-1 renin.
• W-PAM staining was negative in rat and human kidneys and mouse submandibular glands, and results were consistent across different fixatives.

Conclusions:

• The W-PAM staining method is a valuable tool for the specific identification of Ren-1 renin in mouse kidneys.
• This technique can differentiate Ren-1 renin from Ren-2, rat, and human renin.
• W-PAM offers a reliable histochemical approach for Ren-1 renin detection.