MCOLN3 and pulmonary emphysema: We will discuss here the recent discovery that a non-selective Ca2+ permeable cation channel of the TRP (transient receptor potential) superfamily, TRPML3, which is mainly expressed in alveolar macrophages in the lung and which is residing in intracellular compartments, so called endosomes and lysosomes, results in exacerbation of lung tissue injury and emphysema formation under basal, elastase or cigarette smoke exposure when absent or dysfunctional [1].