BRI2 Processing and Its Neuritogenic Role Are Modulated by Protein Phosphatase 1 Complexing

Abstract

BRI2 is a ubiquitously expressed type II transmembrane phosphoprotein. BRI2 undergoes proteolytic processing into secreted fragments and during the maturation process it suffers post-translational modifications. Of particular relevance, BRI2 is a protein phosphatase 1 (PP1) interacting protein, where PP1 is able to dephosphorylate the former. Further, disruption of the BRI2:PP1 complex, using BRI2 PP1 binding motif mutants, leads to increased BRI2 phosphorylation levels. However, the physiological function of BRI2 remains elusive; although findings suggest a role in neurite outgrowth and neuronal differentiation. In the work here presented, BRI2 expression during neuronal development was investigated. This increases during neuronal differentiation and an increase in its proteolytic processing is also evident. To elucidate the importance of BRI2 phosphorylation for both proteolytic processing and neuritogenesis, SH-SY5Y cells were transfected with the BRI2 PP1 binding motif mutant constructs. For the first time, it was possible to show that BRI2 phosphorylation is an important regulatory mechanism for its proteolytic processing and its neuritogenic role. Furthermore, by modulating BRI2 processing using an ADAM10 inhibitor, a dual role for BRI2 in neurite outgrowth is suggested: phosphorylated full-length BRI2 appears to be important for the formation of neuritic processes, and BRI2 NTF promotes neurite elongation. This work significantly contributed to the understanding of the physiological function of BRI2 and its regulation by protein phosphorylation. J. Cell. Biochem. 118: 2752-2763, 2017. © 2017 Wiley Periodicals, Inc.

Nr CAM is a marker for substrate‐selective activation of ADAM 10 in Alzheimer's disease

“…ADAM10 has been shown to differentially regulate neurite outgrowth and axonal guidance through the cleavage of several cell adhesion molecules other than NrCAM (e.g., L1CAM, IgLONs) in distinct anatomical locations and developmental stages (Maretzky et al , ; Saftig & Lichtenthaler, ; Sanz et al , ). For example, while ADAM10 inhibition decreased neurite growth in cultured DRG neurons/explants and chick retinal ganglion cells, it increased the number of neuritic processes in neuronal SH‐SY5Y cells (Paudel et al , ; Meyer et al , ; Martins et al , ; Sanz et al , ). Likewise, inhibition of L1 shedding in cerebellar microexplant cultures only affected neurite outgrowth, when the cultures were placed on L1‐coated coverslips (Maretzky et al , ).…”

In Vitro Cytotoxicity Effects of Zinc Oxide Nanoparticles on Spermatogonia Cells

“…After 16 h, GC-1 cells were treated with fresh media containing 0 and 20 µg/mL of ZnO NPs for 6 h and 12 h. Cells were fixed in 3.7% paraformaldehyde and permeabilized with 0.2% Triton X-100 in 1× PBS. Additionally, cells were blocked with 3% BSA in 1× PBS for 1 h. Cells were incubated with the primary antibodies for 2 h, followed by the secondary antibody for 1 h. To stain filamentous actin (F-actin), Alexa Fluor ® 568 Phalloidin (Molecular probes, Invitrogen, Thermo Fisher Scientific, Waltham, MA, USA; 1:500) was added for 1 h and as previously described [39]. Finally, the coverslips were mounted on a microscope slide with 4 ,6-diamidino-2-phenylindole (DAPI)-containing VECTASHIELD ® Mounting media (Vector Laboratories, Peterborough, UK).…”

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