Airway Resistance Caused by Sphingomyelin Synthase 2 Insufficiency in Response to Cigarette Smoke
AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY
Authors: Gupta, Gayatri; Baumlin, Nathalie; Poon, Justin; Ahmed, Begum; Chiang, Yeun-Po; Railwah, Christopher; Kim, Michael D.; Rivas, Melissa; Goldenberg, Hannah; Elgamal, Ziyad; Salathe, Matthias; Panwala, Apurav A.; Dabo, Abdoulaye; Huan, Chongmin; Foronjy, Robert; Jiang, Xian-Cheng; Wadgaonkar, Raj; Geraghty, Patrick
Abstract
Sphingomyelin synthase is responsible for the production of sphingomyelin (SGM), the second most abundant phospholipid in mammalian plasma, from ceramide, a major sphingolipid. Knowledge of the effects of cigarette smoke on SGM production is limited. In the present study, we examined the effect of chronic cigarette smoke on sphingomyelin synthase (SGMS) activity and evaluated how the deficiency of Sgms2, one of the two isoforms of mammalian SGMS, impacts pulmonary function. Sgms2-knockout and wild-type control mice were exposed to cigarette smoke for 6 months, and pulmonary function testing was performed. SGMS2-dependent signaling was investigated in these mice and in human monocyte-derived macrophages of nonsmokers and human bronchial epithelial (HBE) cells isolated from healthy nonsmokers and subjects with chronic obstructive pulmonary disease (COPD). Chronic cigarette smoke reduces SGMS activity and Sgms2 gene expression in mouse lungs. Sgms2-deficient mice exhibited enhanced airway and tissue resistance after chronic cigarette smoke exposure, but had similar degrees of emphysema, compared with smoke-exposed wild-type mice. Sgms2(-/-) mice had greater AKT phosphorylation, peribronchial collagen deposition, and protease activity in their lungs after smoke inhalation. Similarly, we identified reduced SGMS2 expression and enhanced phosphorylation of AKT and protease production in HBE cells isolated from subjects with COPD. Selective inhibition of AKT activity or overexpression of SGMS2 reduced the production of several matrix metalloproteinases in HBE cells and monocyte-derived macrophages. Our study demonstrates that smoke-regulated Sgms2 gene expression influences key COPD features in mice, including airway resistance, AKT signaling, and protease production.
Identification of submicroscopic genetic changes and precise breakpoint mapping in myelofibrosis using high resolution mate-pair sequencing
AMERICAN JOURNAL OF HEMATOLOGY
Authors: Lasho, Terra; Johnson, Sarah H.; Smith, David I.; Crispino, John D.; Pardanani, Animesh; Vasmatzis, George; Tefferi, Ayalew
Abstract
We used high resolution mate-pair sequencing (HRMPS) in 15 patients with primary myelofibrosis (PMF): eight with normal karyotype and seven with PMF-characteristic cytogenetic abnormalities, including der(6)t(1;6)(q21-23;p21.3) (n=4), der(7)t(1;7)(q10;p10) (n=2), del(20)(q11.2q13.3) (n=3), and complex karyotype (n=1). We describe seven novel deletions/translocations in five patients (including two with normal karyotype) whose breakpoints were PCR-validated and involved MACROD2, CACNA2D4, TET2, SGMS2, LRBA, SH3D19, INTS3, FOP (CHTOP), SCLT1, and PHF17. Deletions with breakpoints involving MACROD2 (lysine deacetylase; 20p12.1) were recurrent and found in two of the 15 study patients. A novel fusion transcript was found in one of the study patients (INTS3-CHTOP), and also in an additional non-study patient with PMF. In two patients with der(6)t(1;6)(q21-23;p21.3), we were able to map the precise translocation breakpoints, which involved KCNN3 and GUSBP2 in one case and HYDIN2 in another. This study demonstrates the utility of HRMPS in uncovering submicroscopic deletions/translocations/fusions, and precise mapping of breakpoints in those with overt cytogenetic abnormalities. The overall results confirm the genetic heterogeneity of PMF, given the low frequency of recurrent specific abnormalities, identified by this screening strategy. Currently, we are pursuing the pathogenetic relevance of some of the aforementioned findings. (c) 2013 Wiley Periodicals, Inc.