In many epithelial cells, epidermal growth factor (EGF) augments the epithelial-mesenchymal transition (EMT) that occurs when cells are treated with transforming growth factor β (TGFβ). We demonstrate that this augmentation requires activation of SH2 domain-containing phosphatase-2 (SHP2; also known as PTPN11), a proto-oncogene. In lung and pancreatic cancer cell lines, reductions in E-cadherin expression, increases in vimentin expression and increases in cell scatter rates were larger when cells were treated with TGFβ and EGF versus TGFβ or EGF alone. SHP2 knockdown promoted epithelial characteristics basally and antagonized EMT in response to TGFβ alone or in combination with EGF. Whereas EGF promoted SHP2 binding to tyrosine phosphorylated GAB1, which promotes SHP2 activity, TGFβ did not induce SHP2 association with phosphotyrosine-containing proteins. Knockdown of endogenous SHP2 and reconstitution with an SHP2 mutant with impaired phosphotyrosine binding ability eliminated the EGF-mediated EMT augmentation that was otherwise restored with wild-type SHP2 reconstitution. These results demonstrate roles for basal and ligandinduced SHP2 activity in EMT and further motivate efforts to identify specific ways to inhibit SHP2, given the role of EMT in tumor dissemination and chemoresistance.

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We investigate the temporal accuracy of two generalized-schemes for the incompressible Navier-Stokes equations. In a widely-adopted approach, the pressure is collocated at the time step t n + 1 while the remainder of the Navier-Stokes equations is discretized following the generalized-scheme. That scheme has been claimed to be second-order accurate in time. We developed a suite of numerical code using inf-sup stable higher-order non-uniform rational B-spline (NURBS) elements for spatial discretization. In doing so, we are able to achieve high spatial accuracy and to investigate asymptotic temporal convergence behavior. Numerical evidence suggests that only first-order accuracy is achieved, at least for the pressure, in this aforesaid temporal discretization approach. On the other hand, evaluating the pressure at the intermediate time step t n+ f recovers second-order accuracy, and the numerical implementation is simplified. We recommend this second approach as the generalized-scheme of choice when integrating the incompressible Navier-Stokes equations.

Background In complex congenital heart disease patients such as those with tetralogy of Fallot, the right ventricle (RV) is subject to pressure overload, leading to RV hypertrophy and eventually RV failure. The mechanisms that promote the transition from stable RV hypertrophy to RV failure are unknown. We evaluated the role of mitochondrial bioenergetics in the development of RV failure. Methods and Results We created a murine model of RV pressure overload by pulmonary artery banding and compared with sham‐operated controls. Gene expression by RNA‐sequencing, oxidative stress, mitochondrial respiration, dynamics, and structure were assessed in pressure overload‐induced RV failure. RV failure was characterized by decreased expression of electron transport chain genes and mitochondrial antioxidant genes (aldehyde dehydrogenase 2 and superoxide dismutase 2) and increased expression of oxidant stress markers (heme oxygenase, 4‐hydroxynonenal). The activities of all electron transport chain complexes decreased with RV hypertrophy and further with RV failure (oxidative phosphorylation: sham 552.3±43.07 versus RV hypertrophy 334.3±30.65 versus RV failure 165.4±36.72 pmol/(s×mL), P <0.0001). Mitochondrial fission protein DRP1 (dynamin 1‐like) trended toward an increase, while MFF (mitochondrial fission factor) decreased and fusion protein OPA1 (mitochondrial dynamin like GTPase) decreased. In contrast, transcription of electron transport chain genes increased in the left ventricle of RV failure. Conclusions Pressure overload‐induced RV failure is characterized by decreased transcription and activity of electron transport chain complexes and increased oxidative stress which are associated with decreased energy generation. An improved understanding of the complex processes of energy generation could aid in developing novel therapies to mitigate mitochondrial dysfunction and delay the onset of RV failure.