Analysis of Damage and Wound Healing in the Retinal Pigmented Epithelium.

Previous studies of retinal pigment epithelium (RPE) morphology found cell-level and spatial patterning differences in many quantitative metrics in comparing normal and disease conditions. However, most of these studies examined eyes from deceased animals. Here we sought to compare noninvasively imaged RPE cells from live mice to histopathology. We describe changes to improve noninvasive imaging of RPE in the live mouse. In retinal diseases, there can be invasion by Iba1-positive cells, which can be detected by noninvasive imaging techniques. Here we can detect potential Iba1-positive cells at the level of the RPE noninvasively.

GADD34 induces cell death through inactivation of Akt following traumatic brain injury.

Neuronal cell death contributes significantly to the pathology of traumatic brain injury (TBI) irrespective of the mode or severity of the injury. Activation of a pro-survival protein, Akt, is known to be regulated by an E3 ligase TRAF6 through a process of ubiquitination-coupled phosphorylation at its T308 residue. Here we show that upregulation of a pro-apototic protein, GADD34, attenuates TRAF6-mediated Akt activation in a controlled cortical impact model of TBI in mice. TBI induces the expression of GADD34 by stimulating binding of a stress inducible transcription factor, ATF4, to the GADD34 promoter. GADD34 then binds with TRAF6 and prevents its interaction with Akt. This event leads to retention of Akt in the cytosol and prevents phosphorylation at the T308 position. Finally, in vivo depletion of GADD34 using a lentiviral knockdown approach leads to a rescue of Akt activation and markedly attenuates TBI-induced cell death.