A cardiac mitochondrial cAMP signaling pathway regulates calcium accumulation, permeability transition and cell death.

Although cardiac cytosolic cyclic 3',5'-adenosine monophosphate (cAMP) regulates multiple processes, such as beating, contractility, metabolism and apoptosis, little is known yet on the role of this second messenger within cardiac mitochondria. Using cellular and subcellular approaches, we demonstrate here the local expression of several actors of cAMP signaling within cardiac mitochondria, namely a truncated form of soluble AC (sACt) and the exchange protein directly activated by cAMP 1 (Epac1), and show a protective role for sACt against cell death, apoptosis as well as necrosis in primary cardiomyocytes. Upon stimulation with bicarbonate (HCO3(-)) and Ca(2+), sACt produces cAMP, which in turn stimulates oxygen consumption, increases the mitochondrial membrane potential (ΔΨm) and ATP production. cAMP is rate limiting for matrix Ca(2+) entry via Epac1 and the mitochondrial calcium uniporter and, as a consequence, prevents mitochondrial permeability transition (MPT). The mitochondrial cAMP effects involve neither protein kinase A, Epac2 nor the mitochondrial Na(+)/Ca(2+) exchanger. In addition, in mitochondria isolated from failing rat hearts, stimulation of the mitochondrial cAMP pathway by HCO3(-) rescued the sensitization of mitochondria to Ca(2+)-induced MPT. Thus, our study identifies a link between mitochondrial cAMP, mitochondrial metabolism and cell death in the heart, which is independent of cytosolic cAMP signaling. Our results might have implications for therapeutic prevention of cell death in cardiac pathologies.

Novel indole-2-carboxamide and cycloalkeno[1,2-b]indole derivatives. Structure-activity relationships for high inhibition of human LDL peroxidation.

Series of indole-2-carboxamide and cycloalkeno[1,2-b]indole derivatives were synthesized and evaluated in order to determine the necessary structural requirements for a high inhibition of human LDL copper-induced peroxidation. Various modulations were systematically performed on the indole and cycloalkeno[1,2-b]indole nuclei as well as on the carboxamide moiety. The best compounds (3c, 3e, 7c, 7f, 7h, 7g, and 7o) are between 5 and 30 times more active than probucol itself. Two of these compounds (3c and 7o) were selected for complementary in vitro and in vivo investigations, which have shown additional properties of interest for the treatment and the prevention of atherosclerosis injuries. Compound 3c was found to have some antiinflammatory properties while compound 7o was proved to protect endothelial cells from the direct cytotoxicity of oxidized LDL with some additional calcium channel blocking properties.

Synthesis and antiproliferative activity of benzocyclobutacarbazol derivatives. A new class of potential antitumor agents.

Several benzocyclobutacarbazol derivatives were synthesized and evaluated for their potential cytotoxic properties. A number of these compounds exhibited significant antiproliferative activity with concomitant interaction with the cell cycle and represent a new class of potential anticancer agents.