
-   DARP, along with other muscle ankyrin repeat proteins like CARP and Ankrd2, is upregulated in response to stress, including cardiac hypertrophy, which is the enlargement of the heart muscle due to increased workload or injury. [PMID: 24736439]
-   Diabetes-related ankyrin repeat protein (DARP/Ankrd23) is expression is enhanced in the skeletal muscle under diabetic conditions due to its role in regulating glucose disposal in skeletal muscle by modulating AMPK activity [PMID: 26398569].

## Summary

ANKRD23 encodes a protein that is part of the muscle ankyrin repeat proteins (MARP) family, specifically involved in muscle gene expression and energy metabolism [CS: 7]. It binds to the N2A region of titin, a giant sarcomeric protein, affecting its phosphorylation by PKA and is itself phosphorylated by PKA and PKC, which could alter its structure or function [CS: 6].

In heart-related diseases and toxicities, the expression of ANKRD23 is often dysregulated [CS: 7]. For instance, in cardiac hypertrophy, where the heart muscle enlarges due to increased workload or injury, ANKRD23 (DARP) is upregulated [CS: 7]. This upregulation likely serves to manage the increased mechanical stress on the heart muscle by modulating the structure and function of sarcomeric proteins like titin, thus maintaining the integrity and function of cardiac muscle cells [CS: 6]. Additionally, in conditions like type 2 diabetes, which can lead to altered energy metabolism in cardiac tissues, the expression of ANKRD23 is affected [CS: 6]. Its role in energy metabolism, particularly under diabetic conditions, suggests its involvement in adapting the heart muscle to altered energy states, possibly by influencing pathways like AMPK activity that are critical in cellular energy homeostasis [CS: 6]. This upregulation in response to stress or altered energy states seems to be a cellular mechanism to counteract the initial stressors, ensuring continued function and survival of cardiac cells under adverse conditions [CS: 7].
