Novel Insights into the PKCβ-dependent Regulation of the Oxidoreductase p66Shc

Abstract

Dysfunctional mitochondria contribute to the development of many diseases and pathological conditions through the excessive production of reactive oxygen species (ROS), and, where studied, ablation of p66Shc (p66) was beneficial. p66 translocates to the mitochondria and oxidizes cytochrome c to yield H2O2, which in turn initiates cell death. PKCβ-mediated phosphorylation of serine 36 in p66 has been implicated as a key regulatory step preceding mitochondrial translocation, ROS production, and cell death, and PKCβ thus may provide a target for therapeutic intervention. We performed a reassessment of PKCβ regulation of the oxidoreductase activity of p66. Although our experiments did not substantiate Ser36 phosphorylation by PKCβ, they instead provided evidence for Ser139 and Ser213 as PKCβ phosphorylation sites regulating the pro-oxidant and pro-apoptotic function of p66. Mutation of another predicted PKCβ phosphorylation site also located in the phosphotyrosine binding domain, threonine 206, had no phenotype. Intriguingly, p66 with Thr206 and Ser213 mutated to glutamic acid showed a gain-of-function phenotype with significantly increased ROS production and cell death induction. Taken together, these data argue for a complex mechanism of PKCβ-dependent regulation of p66 activation involving Ser139 and a motif surrounding Ser213.

p66Shc activation promotes increased oxidative phosphorylation and renders CNS cells more vulnerable to amyloid beta toxicity

“…2 ). Protein kinase C β (PKC-β) is a kinase that phosphorylates p66Shc at the S36 residue, resulting in its activation and mitochondrial translocation 60 – 62 . In order to promote phosphorylation of p66Shc, cells were treated with the phorbol ester 12-Deoxyphorbol 13-phenylacetate 20-acetate (DOPPA), a specific and potent activator of PKC-β 63 – 66 .…”

p66Shc Mediates Mitochondrial Dysfunction Dependent on PKC Activation in Airway Epithelial Cells Induced by Cigarette Smoke

“…Previous studies have demonstrated that PKC β promotes the translocation of p66Shc into the mitochondria of various cells under oxidative stress [ 22 , 32 , 43 ]. In addition, phosphorylated PKC δ can also activate p66Shc in COS-7 and proximal tubular epithelial cells upon oxidative stress stimulation [ 23 , 33 ].…”

Endothelin receptor A and p66Shc regulate spontaneous Ca2+oscillations in smooth muscle cells controlling renal arterial spontaneous motion

“…We have demonstrated that weakened ET-1 activity in afferent arterioles characterizes rats expressing S36A mutant of p66Shc (11). It is generally accepted that phosphorylation of Ser36 in p66Shc triggers its translocation to mitochondria (30,31). An additional indication that S36A mutation decreases the amplitude of Ca 2+ oscillations due to p66Shc cytosolic location is the opposite to the effect of p66ShcKO.…”