Background Genetic variants in the chromosomal region 17q21 are consistently associated with asthma. However, mechanistic studies have not yet linked any of the associated variants to a function that could influence asthma, and as a result, the identity of the asthma gene(s) remains elusive. Objectives We sought to identify and characterize functional variants in the 17q21 locus. Methods We used the Exome Aggregation Consortium (ExAC) browser to identify coding (amino acid-changing) variants in the 17q21 locus. We obtained asthma association measures for these variants in both the GERA cohort (16,274 cases and 38,269 matched controls) and the EVE Consortium study (5,303 asthma cases and 12,560 individuals). Gene expression and protein localization were determined by quantitative RT-PCR and fluorescence immunostaining, respectively. Molecular and cellular studies were performed to determine the functional effects of coding variants. Results Two coding variants (rs2305480 and rs11078928) of the gasdermin B (GSDMB) gene in the 17q21 locus were associated with lower asthma risk in both GERA (OR = 0.92; P= 1.01 × 10−6) and EVE (OR= 0.85; Joint PEVE = 1.31 ×10−13). In GERA, rs11078928 had a minor allele frequency (MAF) of 0.45 in unaffected (non-asthmatic) controls and 0.43 in asthma cases. For European Americans in EVE the MAF of rs2305480 was 0.45 for controls and 0.39 for cases; for all EVE subjects the MAF was 0.32 for controls and 0.27 for cases. GSDMB is highly expressed in differentiated airway epithelial cells, including the ciliated cells. We found that when the GSDMB protein is cleaved by inflammatory caspase-1 to release its N-terminal fragment, potent pyroptotic cell death was induced. The splicing variant rs11078928 deletes the entire exon 6, which encodes 13 amino acids in the critical N-terminus, and abolishes the pyroptotic activity of the GSDMB protein. Conclusions Our study identified a functional asthma variant in the GSDMB gene of the 17q21 locus and implicates GSDMB-mediated epithelial cell pyroptosis in pathogenesis.

(NRG1) is a potential therapeutic agent for the treatment of doxorubicin (Dox)-induced heart failure. NRG1, however, activates the erbB2 receptor, which is frequently overexpressed in breast cancers. It is, therefore, important to understand how NRG1, via erbB2, protects the heart against Dox cardiotoxicity. Here, we studied NRG1-erbB2 signaling in Dox-treated mice hearts and in isolated neonatal rat ventricular myocytes (NRVM). Male C57BL/6 mice were treated with recombinant NRG1 before and daily after a single dose of Dox. Cardiac function was determined by catheterization. Two-week survival was analyzed by the Kaplan-Meier method. Cardiac troponins [cardiac troponin I (cTnI) and cardiac troponin T (cTnT)] and phosphorylated Akt protein levels were determined in mice hearts and in NRVM by Western blot analysis. Activation of caspases and ubiquitinylation of troponins were determined in NRVM by caspase assay and immunoprecipitation. NRG1 significantly improved survival and cardiac function in Dox-treated mice. NRG1 reduced the decrease in cTnI, cTnT, and cardiac troponin C (cTnC) and maintained Akt phosphorylation in Dox-treated mice hearts. NRG1 reduced the decrease in cTnI and cTnT mRNA and proteins in Dox-treated NRVM. Inhibition of erbB2, phosphoinositide 3-kinase (PI3K), Akt, and mTOR blocked the protective effects of NRG1 on cTnI and cTnT in NRVM. NRG1 significantly reduced Dox-induced caspase activation, which degraded troponins, in NRVM. NRG1 reduced Doxinduced proteasome degradation of cTnI. NRG1 attenuates Dox-induced decrease in cardiac troponins by increasing transcription and translation and by inhibiting caspase activation and proteasome degradation of troponin proteins. NRG1 maintains cardiac troponins by the erbB2-PI3K pathway, which may lessen Dox-induced cardiac dysfunction.ErbB2; troponin proteins; signaling NEUREGULIN-1 (NRG1)-ErbB2 signaling is essential for cardiac development and maintaining adult cardiac function (26, 29). ErbB2 was initially detected as an oncogenic variant that was overexpressed in several tumor types (15). Trastuzumab, a humanized monoclonal antibody that binds to and blocks erbB2, significantly reduces recurrence and early mortality in patients with breast cancer who overexpress erbB2 (27,34). A significant increase in congestive heart failure was reported, however, when the anti-erbB2 antibody trastuzumab was used in combination with the chemotherapy drug doxorubicin (Dox) (34). Thus inhibition of erbB2 signaling in patients who receive concurrent therapy with Dox causes an increased risk of cardiotoxicity. We hypothesized, accordingly, that activation of erbB2 signaling by NRG1 may mitigate cardiac dysfunction.Multiple isoforms of NRG1 are synthesized in the endocardium and the endothelium of cardiac vasculature (7,20,24). NRG1 activates its receptors erbB2 and erbB4 on cardiomyocytes (11). NRG1 promotes hypertrophy and proliferation of cardiomyocytes through activation of erbB2 and erbB4 and protects cardiomyocytes from apoptosis (20,24,38). The soluble recombinan...

Sensing misfolded proteins in the endoplasmic reticulum (ER), cells initiate the ER stress response and, when overwhelmed, undergo apoptosis. However, little is known about how cells prevent excessive ER stress response and cell death to restore homeostasis. Here, we report the identification and characterization of cellular suppressors of ER stress-induced apoptosis. Using a genome-wide CRISPR library, we screen for genes whose inactivation further increases ER stress-induced up-regulation of C/EBP homologous protein 10 (CHOP)—the transcription factor central to ER stress-associated apoptosis. Among the top validated hits are two interacting components of the polycomb repressive complex (L3MBTL2 [L(3)Mbt-Like 2] and MGA [MAX gene associated]), and microRNA-124-3 (miR-124-3). CRISPR knockout of these genes increases CHOP expression and sensitizes cells to apoptosis induced by multiple ER stressors, while overexpression confers the opposite effects. L3MBTL2 associates with the CHOP promoter in unstressed cells to repress CHOP induction but dissociates from the promoter in the presence of ER stress, whereas miR-124-3 directly targets the IRE1 branch of the ER stress pathway. Our study reveals distinct mechanisms that suppress ER stress-induced apoptosis and may lead to a better understanding of diseases whose pathogenesis is linked to overactive ER stress response.

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