Identification and biochemical characterization of a heart-muscle cell transforming growth factor beta-1 receptor

PKC isozymes in chronic cardiac disease: possible therapeutic targets?

Cardiovascular disease is the leading cause of death in the United States. Therefore, identifying therapeutic targets is a major focus of current research. Protein kinase C (PKC), a family of serine/threonine kinases, has been identified as playing a role in many of the pathologies of heart disease. However, the lack of specific PKC regulators and the ubiquitous expression and normal physiological functions of the 11 PKC isozymes has made drug development a challenge. Here we discuss the validity of therapeutically targeting PKC, an intracellular signaling enzyme. We describe PKC structure, function, and distribution in the healthy and diseased heart, as well as the development of rationally designed isozyme-selective regulators of PKC functions. The review focuses on the roles of specific PKC isozymes in atherosclerosis, fibrosis, and cardiac hypertrophy, and examines principles of pharmacology as they pertain to regulators of signaling cascades associated with these diseases.

Inhibition of serum and transforming growth factor beta (TGF-beta1)-induced DNA synthesis in confluent airway smooth muscle by heparin

1. Airway remodelling occurs in asthma and involves an increase in airway smooth muscle mass through cell proliferation and hypertrophy. Increased eosinophil density in the airways is a feature of asthma. Eosinophils exhibiting activation in the airways of asthmatics also exhibit increased expression of transforming growth factor beta (TGF-beta1). We have examined the capacity of TGF-beta1 and epidermal growth factor (EGF) to influence airway smooth muscle division and the effect of heparin on TGF-beta1. EGF and serum-induced smooth muscle DNA synthesis in confluent airway smooth muscle cells (ASMC) as an indication of entry into S phase preceding mitogenesis. 2. ASMC were obtained from cell populations growing out from explanted bovine trachealis muscle sections. Cell division was monitored in sparse plated cells by direct cell counting following nuclear staining. Cell DNA synthesis in confluent cells was monitored by uptake of [3H]-thymidine. 3. TGF-beta1 (100 microM) inhibited FBS (10%)-induced smooth muscle division in sparsely plated cells (40%). TGF-beta1 (100 pM) increased cell DNA synthesis (200%) in confluent cells in the presence of bovine serum albumin (BSA, 0.25%). EGF (0.7 nM) also increased airway smooth muscle DNA synthesis (69%) in the presence of BSA (0.25%). The facilitatory effect of TGF-beta1 was observed between 1-100 pM, while that of EGF was observed between 20 200 pM. 4. Heparin inhibited serum and TGF-beta1-induced DNA synthesis in confluent ASMC (55%), consistent with our previous observation of inhibition of division in sparsely populated ASMC (Kilfeather et al., 1995a). This action of heparin was observed between concentrations of 1-100 microg ml(-1). Heparin did not inhibit DNA synthesis in response to EGF. An anti-mitogenic effect of heparin was also observed against responses to combined exposure to TGF-beta1 and EGF. 5. There was a clear inhibitory effect of heparin in absolute terms against serum-induced division in cells plated at 10, 20 and 45 x 10(3) cells cm(-2). The inhibitory effect of heparin was also observed at a plating density of 45,000 cells cm(-2) when responses to serum were expressed as fold-stimulation of basal DNA synthesis. 6. These findings demonstrate a potential role of TGF-beta1, EGF and heparin-related molecules in regulation of airway smooth muscle division.