Molecular defects in cardiac myofibrillar proteins due to thyroid hormone imbalance and diabetes

Area of Science:

• Cardiovascular Endocrinology
• Molecular Cardiology

Background:

• Endocrine abnormalities, including thyroid hormone imbalance and insulin deficiency, frequently lead to cardiac dysfunction, ranging from mild impairment to severe heart failure.
• Cardiac dysfunction in these conditions primarily stems from cardiomyocyte-level changes, not coronary artery alterations.
• Subcellular modifications within cardiomyocytes, driven by altered thyroid hormone and insulin levels, dictate cardiac function.

Purpose of the Study:

• To discuss how myofibrillar proteins are altered by thyroid hormone imbalance and insulin deficiency.
• To explain how structural and functional changes in myofibrillar proteins contribute to cardiac contractile defects.

Main Methods:

• Review of existing literature on myofibrillar protein alterations in endocrine disorders.
• Focus on changes in specific myofibrillar proteins such as actin, myosin, tropomyosin, troponin, titin, desmin, and myosin-binding protein C.

Main Results:

• Thyroid hormone imbalance and insulin deficiency induce molecular and structural alterations in myofibrillar assembly, termed myofibrillar remodeling.
• These myofibrillar remodeling processes can be adaptive or maladaptive depending on the heart's metabolic and functional demands.
• Documented alterations in key myofibrillar proteins are observed in hyperthyroidism, hypothyroidism, and diabetes.

Conclusions:

• Myofibrillar remodeling is a key mechanism linking endocrine abnormalities to cardiac contractile dysfunction.
• Understanding these protein alterations provides insight into the pathogenesis of heart failure in endocrine diseases.