title: Heme and iron induce protein aggregation.
abstract: Heme is an essential molecule expressed in many tissues where it plays key roles as the prosthetic group of several proteins involved in vital physiological and metabolic processes such as gas and electron transport. Structurally, heme is a tetrapyrrole ring containing an atom of iron (Fe) in its center. When released into the extracellular milieu, heme exerts several deleterious effects, which make it an important player in infectious and noninfectious hemolytic diseases where large amounts of free heme are observed such as malaria, dengue fever, β-thalassemia, sickle cell disease and ischemia-reperfusion. Our recent work has uncovered an unappreciated cellular response triggered by heme or Fe, one of its degradation products, on macrophages, which is the formation of protein aggregates known as aggresome-like induced structres (ALIS). This response was shown to be fully dependent on ROS production and the activation of the transcription factor NFE2L2/NRF2. In addition, we have demonstrated that heme degradation by HMOX1/HO-1 (heme oxygenase 1) is required and that Fe is essential for the formation of ALIS, as heme analogs lacking the central atom of Fe are not able to induce these structures. ALIS formation is also observed in vivo, in a model of phenylhydrazine (PHZ)-induced hemolysis, indicating that it is an integral part of the host response to excessive free heme and that it may play a role in cellular homeostasis.
authors.affiliation: a Laboratório de Imunoreceptores e Sinalização , Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil.
authors.forename: Leonardo H
authors.initials: LH
authors.lastname: Travassos
authors.affiliation: a Laboratório de Imunoreceptores e Sinalização , Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil.
authors.forename: Luiz R C
authors.initials: LR
authors.lastname: Vasconcellos
authors.affiliation: b Laboratório de Inflamação e Imunidade , Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil.
authors.forename: Marcelo T
authors.initials: MT
authors.lastname: Bozza
authors.affiliation: b Laboratório de Inflamação e Imunidade , Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil.
authors.forename: Leticia A M
authors.initials: LA
authors.lastname: Carneiro
mesh_terms: D000818:Animals; D006418:Heme / Q000494:pharmacology*; D006801:Humans; D007501:Iron / Q000494:pharmacology*; D008954:Models, Biological; D066329:Protein Aggregates / Q000187:drug effects*
chemical_list: D066329:Protein Aggregates; D006418:Heme; D007501:Iron
keywords: ALIS; NRF2; aggregation; autophagy; ferritin; heme; iron; oxidative stress; protein