Screening for differentially expressed genes in patients with a novel immunodeficiency syndrome

Lysosome-related organelles have versatile functions including protein and lipid degradation, signal transduction, and protein secretion. The molecular elucidation of rare congenital diseases affecting endosomal/lysosomal biogenesis has given insights into physiological functions of the innate and adaptive immune system.. Here, we describe a novel human primary immunodeficiency disorder and provide evidence that the endosomal adaptor protein p14, previously characterized as confining mitogen-activated-protein-kinase (MAPK) signaling to late endosomes, is critical for the function of neutrophils, B-cells, cytotoxic T-cells and melanocytes. Combining genetic linkage studies and transcriptional profiling analysis, we identified a homozygous point mutation in the 3 UTR of p14 (also known as MAPBPIP), resulting in decreased protein expression. In p14-deficient cells, the distribution of late endosomes was severely perturbed, suggesting a novel role for p14 in endosomal biogenesis. These findings have implications for understanding endosomal membrane dynamics, compartmentalization of cell signal cascades, and their role in immunity.

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Bohn G, Allroth A, Brandes G, Thiel J, Glocker E, Schäffer AA, Rathinam C, Taub N, Teis D, Zeidler C, Dewey RA, Geffers R, Buer J, Huber LA, Welte K, Grimbacher B, Klein C