Creation and characterization of a renin knockout rat

Area of Science:

• Cardiovascular Biology
• Renal Physiology
• Gene Editing Technology

Background:

• The renin-angiotensin system is crucial for blood pressure and kidney function regulation.
• Understanding renin's specific role in disease requires in vivo models.
• Zinc-finger nuclease (ZFN) technology offers a method for targeted gene modification.

Purpose of the Study:

• To generate a renin knockout rat using ZFNs to investigate renin's physiological importance.
• To characterize the phenotypic consequences of renin deficiency in vivo.
• To demonstrate the utility of ZFNs for creating cardiovascular disease models in rats.

Main Methods:

• Zinc-finger nucleases (ZFNs) were designed to target the rat renin gene.
• A 10-base pair deletion in exon 5 of the renin gene was induced, causing a frameshift mutation.
• Phenotypic analysis included measurement of body weight, blood pressure, blood urea nitrogen, plasma creatinine, and kidney morphology.

Main Results:

• Renin knockout (Ren-/-) rats exhibited undetectable plasma renin activity and absence of renin protein.
• Ren-/- rats showed significantly reduced body weight and a near 50% decrease in conscious blood pressure on a low-salt diet compared to controls.
• Elevated blood urea nitrogen and plasma creatinine levels, along with abnormal kidney morphology (rudimentary inner medulla, fibrosis, arterial wall thickening, glomerular abnormalities), were observed in Ren-/- rats.

Conclusions:

• The successful generation of the first renin knockout rat validates ZFN technology for creating cardiovascular disease models.
• Renin plays an indispensable role in blood pressure regulation and maintaining normal kidney structure and function, even in a low-renin genetic background.
• This study underscores the critical importance of renin in cardiovascular and renal homeostasis.