Asbestos-induced alveolar epithelial cell apoptosis. The role of endoplasmic reticulum stress response.

Asbestos exposure results in pulmonary fibrosis (asbestosis) and malignancies (bronchogenic lung cancer and mesothelioma) by mechanisms that are not fully understood. Alveolar epithelial cell (AEC) apoptosis is important in the development of pulmonary fibrosis after exposure to an array of toxins, including asbestos. An endoplasmic reticulum (ER) stress response and mitochondria-regulated (intrinsic) apoptosis occur in AECs of patients with idiopathic pulmonary fibrosis, a disease with similarities to asbestosis.

Molecular mechanisms of asbestos-induced lung epithelial cell apoptosis.

Asbestos causes pulmonary fibrosis (asbestosis) and malignancies (bronchogenic lung cancer and mesothelioma) by mechanisms that are not fully elucidated. Accumulating evidence show that alveolar epithelial cell (AEC) apoptosis is a crucial initiating and perpetuating event in the development of pulmonary fibrosis following exposure to a wide variety of noxious stimuli, including asbestos. We review the important molecular mechanisms underlying asbestos-induced AEC apoptosis.

Beta-catenin/T-cell factor signaling is activated during lung injury and promotes the survival and migration of alveolar epithelial cells.

The Wnt/beta-catenin signaling cascade activates genes that allow cells to adopt particular identities throughout development. In adult self-renewing tissues like intestine and blood, activation of the Wnt pathway maintains a progenitor phenotype, whereas forced inhibition of this pathway promotes differentiation. In the lung alveolus, type 2 epithelial cells (AT2) have been described as progenitors for the type 1 cell (AT1), but whether AT2 progenitors use the same signaling mechanisms to control differentiation as rapidly renewing tissues is not known.

Issues associated with assessing nuclear localization of N-terminally unphosphorylated beta-catenin with monoclonal antibody 8E7.

Background: Beta-catenin is a dual function adhesion/transcriptional co-activator protein, and both functions are critical for normal tissue homeostasis. Since the transcriptional functions of beta-catenin are more often implicated in various disease processes, there is much interest in the development and use of reagents to interrogate spatial and temporal evidence of beta-catenin nuclear signaling in cells and tissues. An important study demonstrated that the signaling form of beta-catenin is specifically unphosphorylated at residues S37 and T41, and suggested that this form exhibits a propensity for cytosolic/nuclear accumulation relative to the total pool of beta-catenin.