TY - JOUR
T1 - Missense mutations in the central domains of cardiac Myosin binding protein-C and their potential contribution to hypertrophic cardiomyopathy
AU - Pearce, Amy
AU - Ponnam, Saraswathi
AU - Holt, Mark
AU - Randall, Tom
AU - Beckingham, Rylan
AU - Kho, Ay Lin
AU - Kampourakis, Thomas
AU - Ehler, Elisabeth
PY - 2023/11/20
Y1 - 2023/11/20
N2 - Myosin binding protein-C (MyBP-C) is a multidomain protein that regulates muscle contraction. Mutations in MYBPC3, the gene encoding for the cardiac variant (henceforth called cMyBP-C), are amongst the most frequent causes of hypertrophic cardiomyopathy (HCM). Most mutations lead to a truncated version of cMyBP-C, which is most likely unstable. However, missense mutations have also been reported, which tend to cluster in the central domains of the cMyBP-C molecule. This suggests that these central domains are more than just a passive spacer between the better characterised N- and C- terminal domains. Here we investigated the potential impact of four different missense mutations, E542Q, G596R, N755K and R820Q, which are spread over the domains C3 to C6, on the function of MyBP-C on both the isolated protein level and in cardiomyocytes in vitro. Effect on domain stability, interaction with thin filaments, binding to myosin and subcellular localisation behaviour were assessed. Our studies show that these missense mutations result in slightly different phenotypes at the molecular level, which are mutation specific. The expected functional readout of each mutation provides a valid explanation for why cMyBP-C fails to work as a brake in the regulation of muscle contraction, which eventually results in a HCM phenotype. We conclude that missense mutations in cMyBP- C must be evaluated in context of their domain localisation, their effect on interaction with thin filaments and myosin, and their effect on protein stability to explain how they lead to disease.
AB - Myosin binding protein-C (MyBP-C) is a multidomain protein that regulates muscle contraction. Mutations in MYBPC3, the gene encoding for the cardiac variant (henceforth called cMyBP-C), are amongst the most frequent causes of hypertrophic cardiomyopathy (HCM). Most mutations lead to a truncated version of cMyBP-C, which is most likely unstable. However, missense mutations have also been reported, which tend to cluster in the central domains of the cMyBP-C molecule. This suggests that these central domains are more than just a passive spacer between the better characterised N- and C- terminal domains. Here we investigated the potential impact of four different missense mutations, E542Q, G596R, N755K and R820Q, which are spread over the domains C3 to C6, on the function of MyBP-C on both the isolated protein level and in cardiomyocytes in vitro. Effect on domain stability, interaction with thin filaments, binding to myosin and subcellular localisation behaviour were assessed. Our studies show that these missense mutations result in slightly different phenotypes at the molecular level, which are mutation specific. The expected functional readout of each mutation provides a valid explanation for why cMyBP-C fails to work as a brake in the regulation of muscle contraction, which eventually results in a HCM phenotype. We conclude that missense mutations in cMyBP- C must be evaluated in context of their domain localisation, their effect on interaction with thin filaments and myosin, and their effect on protein stability to explain how they lead to disease.
KW - ATPase; cardiomyopathy; cell culture; cytoskeleton; heart; microscopic imaging; mutant; protein stability
M3 - Article
SN - 0021-9258
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
ER -