The TAZ transcription co-activator promotes cell proliferation and epithelial-mesenchymal transition. TAZ is inhibited by the Hippo tumor suppressor pathway, which promotes TAZ cytoplasmic localization by phosphorylation. We report here that TAZ protein stability is controlled by a phosphodegron recognized by the F-box protein -TrCP and ubiquitylated by the SCF/CRL1 -TrCP E3 ligase. The interaction between TAZ and -TrCP is regulated by the Hippo pathway. Phosphorylation of a phosphodegron in TAZ by LATS primes it for further phosphorylation by CK1⑀ and subsequent binding by -TrCP. Therefore, the Hippo pathway negatively regulates TAZ function by both limiting its nuclear accumulation and promoting its degradation. The phosphodegron-mediated TAZ degradation plays an important role in negatively regulating TAZ biological functions.
Photothermal therapy (PTT) is a promising approach for cancer targeting therapy. However, the temperature-dependent killing of tumor cells in PTT remains unclear. In this study, we report necroptosis plays a role in the anti-tumor effects observed in gold nanorod (GNR)-mediated PTT in melanoma. We first synthesized gold nanorods with a targeting adaptor FA (GNRs-FA), which achieved high efficacy of targeted delivery to melanoma cells. We further demonstrated PTT, precipitated by GNRs-FA under the induction of near-infrared laser, was temperature-dependent. Furthermore, the photothermal killing of melanoma cells showed different patterns of cell death depending on varying temperature in PTT. In a lower temperature at 43 °C, the percentages of apoptosis, necroptosis and necrosis of tumor cells were 10.2%, 18.3%, and 17.6%, respectively, suggesting the cell killing is ineffective at lower temperatures. When the temperature increased to 49 °C, the cell death pattern switched to necrosis dominant (52.8%). Interestingly, when the PTT achieved a moderate temperature of 46 °C, necroptosis was significantly increased (35.1%). Additionally, GNRs-FA/PPT-mediated necroptosis was regulated by RIPK1 pathway. Taken together, this study is the first to demonstrate that temperature-dependent necroptosis is an important mechanism of inducing melanoma cell death in GNR-mediated PTT in addition to apoptosis and necrosis.
Background: TAZ overexpression is implicated in cancer development.
Results:The N-terminal phosphodegron is phosphorylated by GSK3, which creates a binding site for -TrCP, resulting in TAZ ubiquitylation and degradation.
Conclusion:The N-terminal phosphodegron regulates TAZ stability in response to the dysregulated PI3K pathway. Significance: Our study reveals the underlying mechanism of TAZ N-terminal phosphodegron regulation in elevated TAZ cancers with a dysregulated PTEN/PI3K pathway.
CRB1 mutations lead to early-onset severe loss of vision with thickened, disorganized, nonseeing retina. Impaired peripheral vision can persist in late disease stages. Rd8 mice also have a disorganized retina, but there is sufficient photoreceptor integrity to produce largely normal retinal function. Differences between human and mouse diseases will complicate proof-of-concept studies intended to advance treatment initiatives.
Reductions in the photoreceptor laminae overlying drusen were detectable and this is consistent with histological studies revealing neuronal degeneration in AMD. ONL thickening in some macular areas of AMD eyes has not been previously reported and may be an early phenotypic marker for photoreceptor stress, as it has been speculated to be in hereditary retinal degenerations.
Cell adhesion to material surfaces is a fundamental phenomenon in tissue response to implanted devices, and an important consideration in tissue engineering. For example, elucidation of phenomena associated with adhesion of chondrocytes to biomaterials is critical in addressing the difficult problem of articular cartilage regeneration. The first objective of this study was to measure the mechanical adhesiveness characteristics of individual rabbit articular chondrocytes as a function of seeding time to provide further understanding of the cell adhesion process. The second objective was to quantify the force required to separate the plasma membrane from the underlying cytoskeleton as a function of seeding time. After culturing chondrocytes on glass coverslips for I , 2, 4, 6 h, two biomechanical tests were performed on single chondrocytes: (i) mechanical adhesiveness measurement by the cytodetacher; and (ii) plasma membrane tether formation force measurement by optical tweezers. Cell mechanical adhesiveness increased from 231 i 149 Pa at I h to 1085 f 21 1 Pa at 6 h. The cell contact area with the substrata increased from 161 i 52 pm2 at 1 h to 369 i 105 pm2 at 6 h. The tether formation force increased from 232 =k 23 p N at 1 h to 591 i 17 pN at 6 h. Moreover, fluorescence staining by rhodamine-phalloidin demonstrated the process of actin spreading within the cytoskeleton from 0.5 to 6 h and allowed for measurement of cell height which was found to decrease from 12.3 f 2.9 pm at 0.5 h to 6.2 i 0.9 pm at 6 h.
RPGR mutations lead to progressive loss of rod and cone vision, but show different patterns of residual photoreceptor disease expression. Knowledge of the patterns should guide treatment strategies. Rpgr-cko mice had onset of degeneration at relatively young ages and progressive photoreceptor disease. The natural history in this model will permit preclinical proof-of-concept studies to be designed and such studies should advance progress toward human therapy.
Mutations in GUCY2D are associated with recessive Leber congenital amaurosis-1 (LCA1). GUCY2D encodes photoreceptor-specific, retinal guanylate cyclase-1 (RetGC1). Reports of retinal degeneration in LCA1 are conflicting; some describe no obvious degeneration and others report loss of both rods and cones. Proof of concept studies in models representing the spectrum of phenotypes is warranted. We have previously demonstrated adeno-associated virus (AAV)-mediated RetGC1 is therapeutic in GC1ko mice, a model exhibiting loss of cones only. The purpose of this study was to characterize AAV-mediated gene therapy in the RetGC1/RetGC2 double knockout (GCdko) mouse, a model lacking rod and cone function and exhibiting progressive loss of both photoreceptor subclasses. Use of this model also allowed for the evaluation of the functional efficiency of transgenic RetGC1 isozyme. Subretinal delivery of AAV8(Y733F) vector containing the human rhodopsin kinase (hGRK1) promoter driving murine Gucy2e was performed in GCdko mice at various postnatal time points. Treatment resulted in restoration of rod and cone function at all treatment ages and preservation of retinal structure in GCdko mice treated as late as 7 weeks of age. Functional gains and structural preservation were stable for at least 1 year. Treatment also conferred cortical-and subcortical-based visually-guided behavior. Functional efficiency of transgenic RetGC1 was indistinguishable from that of endogenous isozyme in congenic wild-type (WT) mice. This study clearly demonstrates AAV-mediated RetGC1 expression restores function to and preserves structure of rod and cone photoreceptors in a degenerative model of retinal guanylate cyclase deficiency, further supporting development of an AAV-based vector for treatment of LCA1.
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