Plakophilin-2: a cell-cell adhesion plaque molecule of selective and fundamental importance in cardiac functions and tumor cell growth

Within the characteristic ensemble of desmosomal plaque proteins, the armadillo protein plakophilin-2 (Pkp2) is known as a particularly important regulatory component in the cytoplasmic plaques of various other cell–cell junctions, such as the composite junctions (areae compositae) of the myocardiac intercalated disks and in the variously-sized and -shaped complex junctions of permanent cell culture lines derived therefrom. In addition, Pkp2 has been detected in certain protein complexes in the nucleoplasm of diverse kinds of cells. Using a novel set of highly sensitive and specific antibodies, both kinds of Pkp2, the junctional plaque-bound and the nuclear ones, can also be localized to the cytoplasmic plaques of diverse non-desmosomal cell–cell junction structures. These are not only the puncta adhaerentia and the fasciae adhaerentes connecting various types of highly proliferative non-epithelial cells growing in culture but also some very proliferative states of cardiac interstitial cells and cardiac myxomata, including tumors growing in situ as well as fetal stages of heart development and cultures of valvular interstitial cells. Possible functions and assembly mechanisms of such Pkp2-positive cell–cell junctions as well as medical consequences are discussed

Mutations with pathogenic potential in proteins located in or at the composite junctions of the intercalated disk connecting mammalian cardiomyocytes: a reference thesaurus for arrhythmogenic cardiomyopathies and for Naxos and Carvajal diseases

In the past decade, an avalanche of findings and reports has correlated arrhythmogenic ventricular cardiomyopathies (ARVC) and Naxos and Carvajal diseases with certain mutations in protein constituents of the special junctions connecting the polar regions (intercalated disks) of mature mammalian cardiomyocytes. These molecules, apparently together with some specific cytoskeletal proteins, are components of (or interact with) composite junctions. Composite junctions contain the amalgamated fusion products of the molecules that, in other cell types and tissues, occur in distinct separate junctions, i.e. desmosomes and adherens junctions. As the pertinent literature is still in an expanding phase and is obviously becoming important for various groups of researchers in basic cell and molecular biology, developmental biology, histology, physiology, cardiology, pathology and genetics, the relevant references so far recognized have been collected and are presented here in the following order: desmocollin-2 (Dsc2, DSC2), desmoglein-2 (Dsg2, DSG2), desmoplakin (DP, DSP), plakoglobin (PG, JUP), plakophilin-2 (Pkp2, PKP2) and some non-desmosomal proteins such as transmembrane protein 43 (TMEM43), ryanodine receptor 2 (RYR2), desmin, lamins A and C, striatin, titin and transforming growth factor-β3 (TGFβ3), followed by a collection of animal models and of reviews, commentaries, collections and comparative studies

Intracoronary hypothermia before reperfusion to reduce reperfusion injury in acute myocardial infarction:a novel hypothesis and technique

\u3cp\u3eBecause current reperfusion strategies in acute myocardial infarction (AMI) seem to be exhausted in terms of additional mortality benefit, there remains a need for new methods to attenuate reperfusion injury and, thereby, further reduce myocardial infarct size and improve long-term survival. Therapeutic hypothermia (32-35°C) diminishes reperfusion injury and reduces infarct size in a variety of animal models of AMI if provided before reperfusion. In human studies this reduction has not been confirmed so far, most likely because systemic cooling acts slowly, and therefore, the target temperature is not reached in time or at all in a substantial number of patients. Furthermore, systemic cooling can cause adverse effects such as severe shivering, volume overload, and an enhanced adrenergic state. In most randomized clinical trials, however, subgroups of patients with anterior myocardial infarction that reached the target temperature before reperfusion did show a reduction in infarct size. To transform therapeutic hypothermia into a clinically feasible treatment for AMI, its method must be modified. An ideal technique should be quick enough to achieve sufficient myocardial hypothermia before reperfusion, without significant delay and without the adverse effects of systemic cooling. In this review, we propose a novel, potentially feasible method of selective intracoronary hypothermia to overcome the problems encountered with prior techniques.\u3c/p\u3