Protein kinase C and cardiac dysfunction: a review

Heart failure (HF) is a physiological state in which cardiac output is insufficient to meet the needs of the body. It is a clinical syndrome characterized by impaired ability of the left ventricle to either fill or eject blood efficiently. HF is a disease of multiple aetiologies leading to progressive cardiac dysfunction and it is the leading cause of deaths in both developed and developing countries. HF is responsible for about 73,000 deaths in the UK each year. In the USA, HF affects 5.8 million people and 550,000 new cases are diagnosed annually. Cardiac remodelling (CD), which plays an important role in pathogenesis of HF, is viewed as stress response to an index event such as myocardial ischaemia or imposition of mechanical load leading to a series of structural and functional changes in the viable myocardium. Protein kinase C (PKC) isozymes are a family of serine/threonine kinases. PKC is a central enzyme in the regulation of growth, hypertrophy, and mediators of signal transduction pathways. In response to circulating hormones, activation of PKC triggers a multitude of intracellular events influencing multiple physiological processes in the heart, including heart rate, contraction, and relaxation. Recent research implicates PKC activation in the pathophysiology of a number of cardiovascular disease states. Few reports are available that examine PKC in normal and diseased human hearts. This review describes the structure, functions, and distribution of PKCs in the healthy and diseased heart with emphasis on the human heart and, also importantly, their regulation in heart failure

The susceptibility of Aire(-/-) mice to experimental myasthenia gravis involves alterations in regulatory T cells

The autoimmune regulator (Aire) is involved in the prevention of autoimmunity by promoting thymic expression of tissue restricted antigens which leads to elimination of self-reactive T cells. We found that Aire knockout (KO) mice as well as mouse strains that are susceptible to experimental autoimmune myasthenia gravis (EAMG) have lower thymic expression of acetylcholine receptor (AChR- the main autoantigen in MG), compared to wild type (WT) mice and EAMG-resistant mouse strains, respectively. We demonstrated that Aire KO mice have a significant and reproducible lower frequency of CD4+Foxp3+ cells and a higher expression of Th17 markers in their thymus, compared to wild type (WT) mice. These findings led us to expect that Aire KO mice would display increased susceptibility to EAMG. Surprisingly, when EAMG was induced in young (2 month-old) mice, EAMG was milder in Aire KO than in WT mice for several weeks until the age of about 5 months. However, when EAMG was induced in relatively aged (6 month-old) mice, Aire KO mice presented higher disease severity than WT controls. This age-related change in susceptibility to EAMG correlated with an elevated proportion of Treg cells in the spleens of young but not old KO, compared to WT mice, suggesting a role for peripheral Treg cells in the course of disease. Our observations point to a possible link between Aire and Treg cells and suggest an involvement for both in the pathogenesis of myasthenia.Revital Aricha, Tali Feferman, Hamish S. Scott, Miriam C. Souroujon, Sonia Berrih-Aknin, Sara Fuch

Increased gene expression of acetylcholine receptor and myogenic factors in passively transferred experimental autoimmune myasthenia gravis

The passive transfer of myasthenia gravis by injection of mAb against muscle acetylcholine receptor (AChR) alpha-subunit, results in increased expression of AChR subunit genes, mainly at synaptic regions. The gene expression of AChR and of other muscle-specific proteins is regulated in a similar manner in passively transferred experimental autoimmune myasthenia gravis (EAMG) and in AChR-induced EAMG. Administration of AChR-specific mAb leads to a significant reduction in muscle AChR content and to an elevation in the mRNA levels corresponding to the adult, synaptic type of the receptor, as shown by Northern blot and in situ hybridization analyses. The mRNA levels of the myogenic factors myogenin and MRF4 are also increased moderately, whereas MyoD transcript levels remain unchanged. Thus, passive transfer of EAMG by mAb directed to defined epitopes of AChR alpha-subunit provides a suitable model for analyzing and following the cascade of molecular events triggered by anti-AChR immunopathologic antibodies and may shed light on the regulatory mechanisms underlying the human disease as well