Oligosaccharide chains of newly synthesized membrane receptors are trimmed and modified to optimize their trafficking and/or signalling before delivery to the cell surface. For most membrane receptors, the functional significance of oligosaccharide chain modification is unknown. During the maturation of Rh1 rhodopsin, a Drosophila light receptor, the oligosaccharide chain is trimmed extensively. Neither the functional significance of this modification nor the enzymes mediating this process are known. Here, we identify a dmppe (Drosophila metallophosphoesterase) mutant with incomplete deglycosylation of Rh1, and show that the retained oligosaccharide chain does not affect Rh1 localization or signalling. The incomplete deglycosylation, however, renders Rh1 more sensitive to endocytic degradation, and causes morphological and functional defects in photoreceptors of aged dmppe flies. We further demonstrate that the dMPPE protein functions as an Mn 2 þ /Zn 2 þ -dependent phosphoesterase and mediates in vivo dephosphorylation of a-Man-II. Most importantly, the dephosphorylated a-Man-II is required for the removal of the Rh1 oligosaccharide chain. These observations suggest that the glycosylation status of membrane proteins is controlled through phosphorylation/dephosphorylation, and that MPPE acts as the phosphoesterase in this regulation.

Group 2 innate lymphoid cells (ILC2s) are a set of effectors that mediate the expulsion of helminthic parasites but also drive allergic lung inflammation. As innate agents, they do not recognize Ag, instead, they are sensitive to alarmin engagement, upon which they produce type 2 cytokines that amplify adaptive immunity. Their lymphoid identity appoints them as an intriguing group of unconventional cells; however, increasing evidence is unraveling a series of unprecedented functions that <5 years ago were unthinkable for ILC2s, such as acquiring a proinflammatory identity that enables them to support TH1 immune responses. Their plastic nature has allowed the characterization of ILC2s in more detail than ever; however, the novelty of ILC2 biology requires constant updates and recapitulations. This review provides an overview of ILC2s and describes memory ILC2, regulatory ILC2, inflammatory ILC2, and type 1 ILC2 subsets based on activation status, tissue environments, and function.

Type 2 innate lymphoid cells (ILC2s) were discovered approximately ten years ago and their clinical relevance is gaining greater importance. However, their successful isolation from mammalian tissues and in vitro culture and expansion continues to pose challenges. This is partly due to their scarcity compared to other leukocyte populations, but also because our current knowledge of ILC2 biology is incomplete. This study is focused on ST2+ IL-25Rlo lung resident ILC2s and demonstrate for the first time a methodology allowing mouse type 2 innate lymphoid cells to be cultured, and their numbers expanded in serum-free medium supplemented with Interleukins IL-33, IL-2, IL-7 and TSLP. The procedures described methods to isolate ILC2s and support their growth for up to a week while maintaining their phenotype. During this time, they significantly expand from low to high cell concentrations. Furthermore, for the first time, sub-cultures of primary ILC2 purifications in larger 24- and 6-well plates were undertaken in order to compare their growth in other media. In culture, ILC2s had doubling times of 21 h, a growth rate of 0.032 h−1 and could be sub-cultured in early or late phases of exponential growth. These studies form the basis for expanding ILC2 populations that will facilitate the study and potential applications of these rare cells under defined, serum-free conditions.