Browsing by Author "Tuchek, Chad A."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    A Compact Blast-Induced Traumatic Brain Injury Model in Mice
    (Oxford University Press, 2016-02) Wang, Hongxing; Zhang, Yi Ping; Cai, Jun; Shields, Lisa B. E.; Tuchek, Chad A.; Shi, Riyi; Li, Jianan; Shields, Christopher B.; Xu, Xiao-Ming; Neurological Surgery, School of Medicine
    Blast-induced traumatic brain injury (bTBI) is a common injury on the battlefield and often results in permanent cognitive and neurological abnormalities. We report a novel compact device that creates graded bTBI in mice. The injury severity can be controlled by precise pressures that mimic Friedlander shockwave curves. The mouse head was stabilized with a head fixator, and the body was protected with a metal shield; shockwave durations were 3 to 4 milliseconds. Reflective shockwave peak readings at the position of the mouse head were 12 6 2.6 psi, 50 6 20.3 psi, and 100 6 33.1 psi at 100, 200, and 250 psi predetermined driver chamber pressures, respectively. The bTBIs of 250 psi caused 80% mortality, which decreased to 27% with the metal shield. Brain and lung damage depended on the shockwave duration and amplitude. Cognitive deficits were assessed using the Morris water maze, Y-maze, and open-field tests. Pathological changes in the brain included disruption of the blood-brain barrier, multifocal neuronal and axonal degeneration, and reactive gliosis assessed by Evans Blue dye extravasation, silver and Fluoro-Jade B staining, and glial fibrillary acidic protein immunohistochemistry, respectively. Behavioral and pathological changes were injury severity-dependent. This mouse bTBI model may be useful for investigating injury mechanisms and therapeutic strategies associated with bTBI.
  • Thumbnail Image
    Item
    HE AMOT FAMILY OF PROTEINS BINDS AND ACTIVATES NEDD4 FAMILY LIGASES TO PROMOTE THE UBIQUITINATION OF LATS AND YAP
    (Office of the Vice Chancellor for Research, 2012-04-13) Adler, Jacob J.; Heller, Brigitte L.; Tuchek, Chad A.; Ingham, Robert J.; Wells, Clark D.
    Amot adaptor proteins bind and integrate signaling that controls cell po-larity and growth. All three Amot family members (Amot, AmotL1 and AmotL2) directly bind YAP; a transcriptional co-activator that controls the expression of genes involved in organ homeostasis and cell growth. Preven-tion of nuclear accumulation of YAP by either sequestration or degradation in the cytosol abolishes its transcriptional functions and is a major mechanism for growth arrest in response to cellular differentiation. This is mainly thought to be regulated by phosphorylation of YAP by the Hippo kinases LATS1/2. Recently, binding by the Amot proteins was also found to inhibit YAP by sequestering it in the cytosol through both LATS dependent and in-dependent mechanisms. This study identifies a novel mechanism whereby Amot proteins control YAP activation in a Hippo independent mechanism by coupling it to ubiquitination by Nedd4 family ligases. Amot proteins mediate the coupling of Nedd4 ligases with YAP by simultaneously binding both pro-teins via multiple PY motifs that are recognized by WW domains in both YAP and Nedd4. Binding of Nedd4 by Amot is also shown to relieve the auto-inhibition of its ligase activity. This may be a direct consequence of binding Amot or from being re-targeted in cells by Amot proteins to endosomes. Im-portantly, Amot induced ubiquitination of YAP by Nedd4 proteins is shown to enhance the residence of YAP in the nucleus and in YAP activated transcrip-tion. Taken together our data suggest that Amot couples Nedd4 family ubiq-uitin ligases with the transcriptional co-activator YAP to drive the ubiquitination and activation of YAP.