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Nanopharmaceuticals in Cardiovascular Medicine
Published in Harishkumar Madhyastha, Durgesh Nandini Chauhan, Nanopharmaceuticals in Regenerative Medicine, 2022
Ramandeep Singh, Anupam Mittal, Maryada Sharma, Ajay Bahl, Madhu Khullar
Troponins are a group of proteins found in the cardiac muscles and skeletal muscles that help to control and regulate the contraction of the muscles. There are three variants of the protein troponin, i.e., troponin I, troponin C, and troponin T. In case of cardiovascular diseases where cardiomyocytes are damaged, troponin C and troponin I are expressed in higher quantities in blood. The levels of both troponin C and troponin I are undetectable in normal conditions; therefore, they serve as potential biomarkers for cardiovascular diseases. Efforts are being made into developing these two biomolecules into biomarkers (Park et al., 2020).
Striated MusclesSkeletal and Cardiac Muscles
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The globular protein troponin (molecular weight 70,000 Da) complex is located at regular intervals along the tropomyosin chains. There are three subunits: (i) troponin-T binds troponin complex to tropomyosin, (ii) troponin-I inhibits actomyosin ATPase and (iii) troponin-C binds calcium. In the presence of calcium, the configuration of the troponin-T complex alters. This exposes or uncovers the myosin-binding site and allows cross-bridges to form between myosin and actin, and enables the muscle to contract.
Cardiac biomarkers in acute coronary syndrome
Published in K Sarat Chandra, AJ Swamy, Acute Coronary Syndromes, 2020
Cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are more sensitive and specific markers than CK-MB in detecting myocardial necrosis and have become the preferred biomarkers for the diagnosis of AMI. Troponin is a complex of three proteins that is integral to muscle contraction in skeletal and cardiac muscle, regulating the calcium-mediated interaction between actin and myosin. Its three subunits are TnC, TnI and TnT. Troponin C binds to calcium ions in order to produce movement; troponin T binds to tropomyosin, interlocking it to form a troponin-tropomyosin complex; troponin I binds to actin in thin myofilaments to hold the troponin-tropomyosin complex in place. Troponin C has an identical amino-acid sequence in both skeletal and cardiac tissues and, thus, it has no potential as a cardiac specific marker. However, troponin T and troponin I have different isoforms in cardiac and skeletal muscle, encoded by separated genes, and consequently, have different amino-acid sequences. The respective cardiac isoforms of TnT (cTnT) and TnI (cTnI) allow production of antibodies that exclusively recognize these myocardial-specific proteins. Higher diagnostic sensitivity and specificity require specimen collection at patient presentation, 6–9 hours later and at 12–24 hours if clinical suspicion is high and earlier results are negative. Indeed, troponin is not considered as an early biomarker of myocardial necrosis: cardiac troponins need 4–10 hours after symptoms onset to appear in serum, and peak at 12–48 hours, remaining then abnormal for several days to two weeks [10–12].
LC-MS/MS: A sensitive and selective analytical technique to detect COVID-19 protein biomarkers in the early disease stage
Published in Expert Review of Proteomics, 2023
Siva Nageswara Rao Gajula, Ankita Sahebrao Khairnar, Pallavi Jock, Nikita Kumari, Kendre Pratima, Vijay Munjal, Pavan Kalan, Rajesh Sonti
Troponin C, troponin1, and troponin T are three regulatory proteins that form the troponin complex and are essential for skeletal and cardiac muscle contraction. Cardiac troponin is a prognostic and diagnostic biomarker in acute coronary syndrome and myocardial infarction [115,116]. Many investigations manifest that COVID-19 patients with heart diseases such as myocardial infarction have a higher mortality rate attributed to elevated cardiac troponin levels [117–120]. Shi et al. demonstrated that among 416 COVID-19 patients, 1 in 5 had elevated cardiac troponin levels [120]. Furthermore, recent studies have shown that cardiac troponin is higher in critically ill and non-survivor patients than in infected patients [121,122]. Schneck et al. developed a selective and sensitive LC-MS/MS method for detecting and quantifying cardiac troponin I in human plasma using targeted mass spectrometry [123].
Early clinical and pre-clinical therapy development in Nemaline myopathy
Published in Expert Opinion on Therapeutic Targets, 2022
Gemma Fisher, Laurane Mackels, Theodora Markati, Anna Sarkozy, Julien Ochala, Heinz Jungbluth, Sithara Ramdas, Laurent Servais
A second level of specificity to consider relates to the need to target skeletal rather than cardiac striated muscle or smooth muscle: Fast skeletal muscle fibers have different myosin and troponin isoforms compared to cardiac and slow skeletal muscle. Smooth muscle does not express troponin [90], whereas Troponin T, encoded by NM genes TNNT1 and TNNT3 are predominantly expressed in skeletal but not cardiac muscle [93,134]. Troponin C is encoded by the gene TNNC1 in both cardiac and skeletal muscle, whereas cardiac troponin T and I are encoded by different genes, TNNI3 and TNNT2 [135], and have amino acid sequences different from their skeletal muscle counterparts with a discrepancy of up to 40%. LMOD3 is expressed predominantly in skeletal muscle although there is some cardiac expression [83]. In many of the treatment approaches discussed, side effects from therapies also acting on cardiac and smooth muscle must be considered but, considering that majority of NM causative genes are only expressed in skeletal muscle (Table 1), these side effects are unlikely in gene-specific approaches [16,46]. However, cardiac side effects may be more likely with other approaches such as with drugs affecting calcium sensitivity and IGF-1 [109,136].
Differential expression of MAP3K7 and TROPONIN C proteins and related perturbations in renal amyloidosis
Published in Expert Review of Proteomics, 2020
Nimisha Gupta, Tahreem Sahar, Dinesh Khullar, S.K. Jain, Saima Wajid
Troponin C (cTnC) is a calcium-binding subunit of protein and a part of the troponin complex. The troponin complex consists of 3 regulatory proteins – troponin T, troponin I, and troponin C and is located on the myofibrillar thin (actin) filament of striated (skeletal and cardiac) muscle. cTnC is 18 kDa protein which regulates the activation of the actin filaments [21]. Recently, cTnC was found to be differentially expressed in the primary cutaneous amyloidosis patients [22]. Moreover, an increased level of troponin T was found in patients with end-stage renal diseases (ESRD) and obstructive sleep apnea [23]. Another study has also revealed an elevated level of cardiac troponin in patients with chronic kidney diseases including ESRD. Patients with ESRD have elevated cardiac troponin due to the cardiac injury associated with chronic structural heart diseases. Additionally, we observed that other subunits (cTnT, cTnI) of troponin complex closely interact and are involved in striated muscle contraction pathway. Patients with primary systemic amyloidosis also reported elevated levels of cTnT and cTnI [24]. Bobyleva et al. noticed that MyBP-C, another interactor of troponin C has the potential to form amyloids aggregates in vitro (Figure 4, Supplementary Table 4) [25]. Two different isoforms of human TnC encoded by individual genes have been described, including an isoform exclusively expressed in fast-twitch skeletal tissue and an isoform expressed in both cardiac and slow-twitch skeletal muscle tissue. There is significant homology between the cardiac and TnC isoforms which reduces cardiac specificity; consequently, detection of TnC has limited diagnostic utility in ACS. Significant cardiac involvement is thought to be rare in AA amyloidosis. Cardiac involvement could be the initial presentation of amyloidosis. Cardiac involvement occurs in up to 50% of patients with AL amyloidosis and up to 5% in patients with AA amyloidosis [26]. In the present study, none of the patients was reported to have cardiac amyloidosis. In this study, we found elevated expression of troponin C in RA samples as compared to controls. Hence, the role of troponin C in chronic kidney diseases and amyloidosis may be attributed to the presence and upregulation of cTnC in RA samples.