Developmental regulation of calcineurin isoforms in the rodent kidney: association with COX-2

Area of Science:

• Nephrology
• Developmental Biology
• Molecular Biology

Background:

• Calcineurin (Cn)-Aalpha-deficient mice exhibit postnatal kidney development abnormalities, mirroring cyclooxygenase (COX)-2-deficient mice.
• Understanding the interplay between Cn and COX-2 is vital for elucidating kidney development pathways.

Purpose of the Study:

• To investigate the expression and regulation of Cn isoforms in the developing kidney postnatally.
• To further characterize the relationship between Cn and COX-2 during kidney development.

Main Methods:

• Immunoblotting and real-time PCR to assess Cn isoform and COX-2 expression.
• Immunohistochemistry to determine cellular localization of Cn isoforms and COX-2.
• Pharmacological inhibition of Cn using cyclosporine A and genetic deletion of Cn isoforms in mice.

Main Results:

• All three Cn isoforms (Cn-Aalpha, -Abeta, -B) showed parallel increases in protein expression during the first postnatal week, followed by a gradual decline.
• Cn-Aalpha and -Abeta mRNA expression followed similar developmental patterns, while Cn-B1 mRNA was not significantly induced early postnatally.
• Cn-Aalpha, Cn-Abeta, and COX-2 were colocalized in the thick ascending limb and macula densa.
• Cyclosporine A treatment suppressed renal COX-2 expression; Cn-Aalpha deletion, but not Cn-Abeta deletion, significantly reduced postnatal renal COX-2 expression.

Conclusions:

• Renal Cn isoforms are developmentally regulated during the postnatal period.
• Cn isoforms, particularly Cn-Aalpha, play a role in regulating COX-2 expression.
• These findings suggest a functional interaction between Cn isoforms and COX-2 in postnatal kidney development.