Article

Identification of peripherin as a Akt substrate in neurons

Graduate School of Engineering, Osaka City University, Ōsaka, Ōsaka, Japan
Journal of Biological Chemistry (Impact Factor: 4.57). 09/2007; 282(32):23491-9. DOI: 10.1074/jbc.M611703200
Source: PubMed

ABSTRACT Activation of Akt-mediated signaling pathways is crucial for survival and regeneration of injured neurons. In this study, we attempted to identify novel Akt substrates by using an antibody that recognized a consensus motif phosphorylated by Akt. PC12 cells that overexpressed constitutively active Akt were used. Using two-dimensional PAGE, we identified protein spots that exhibited increased immunostaining of the antibody. Mass spectrometry revealed several major spots as the neuronal intermediate filament protein, peripherin. Using several peripherin fragments, the phosphorylation site was determined as Ser(66) in its head domain in vitro. Furthermore, a co-immunoprecipitation experiment revealed that Akt interacted with the head domain of peripherin in HEK 293T cells. An antibody against phosphorylated peripherin was raised, and induction of phosphorylated peripherin was observed not only in Akt-activated cultured cells but also in nerve-injured hypoglossal motor neurons. These results suggest that peripherin is a novel substrate for Akt in vivo and that its phosphorylation may play a role in motor nerve regeneration.

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    • "The functional characteristics that distinguish peripherin's role during these events may be driven partly by the specific sets of peripherin isoforms expressed by injured or diseased neurons. Recent insights into peripherin expression and assembly have revealed complex intra-isoform associations that are tissue-specific and regulated through a number of different post-transcriptional processes, including alternative splicing and translation , nitrotyrosination, and phosphorylation (Aletta et al. 1989; Huc et al. 1989; Landon et al. 2000; Konishi et al. 2007; Tedeschi et al. 2007; McLean et al. 2008; Xiao et al. 2008). Our previous findings have demonstrated that there are physiological requirements for the production and regulation of different peripherin isoforms. "
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    • "It is interesting to speculate why Per-45 is the major isoform expressed in the brain. It has recently been found that Akt, a serine/threonine protein kinase critical to the survival and regeneration of injured neurons, interacts with the N-terminal head domain of peripherin, phosphorylating Ser66 (Konishi et al. 2007). Although the functional relevance of phosphorylation of peripherin by Akt is unknown, it is increasingly recognized that IF proteins are important mediators of cell signaling (Paramio and Jorcano 2002; Kim and Coulombe 2007). "
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