Abstract
Neuroglobin (Ngb) is a heme protein expressed in the vertebrate brain. We previously engineered a chimeric Ngb protein, in which module M1 of human Ngb is replaced by that of zebrafish Ngb, and showed that the chimeric ZHHH Ngb has a cell membrane‐penetrating activity similar to that of zebrafish Ngb and also rescues cells from death caused by hypoxia/reoxygenation as does human Ngb. Recently, it was reported that overexpression of mammalian Ngb in neuronal cells induces neurite outgrowth. In this study, we performed neurite outgrowth assays of chimeric Ngb using rat pheochromocytoma PC12 cells. Addition of chimeric Ngb, but not human or zebrafish Ngb, exogenously to the cell medium induces neurite outgrowth. On the other hand, the K7A/K9Q chimeric Ngb double mutant, which cannot translocate into cells, did not induce neurite outgrowth, suggesting that the cell membrane‐penetrating activity of the chimeric Ngb is crucial for its neurite outgrowth‐promoting activity. We also prepared several site‐directed chimeric Ngb mutants and demonstrated that residues crucial for neurite outgrowth‐inducing activity of the chimeric Ngb are not exactly the same as those for its neuroprotective activity.
Highlights
Neuroglobin (Ngb) is a heme protein expressed in the vertebrate brain
We found that human Ngb binds exclusively to the GDP-bound form of the a-subunits of heterotrimeric Gi/o proteins (Gai/o), which are present in lipid rafts and inhibit adenylate cyclase activity, thereby acting as guanine nucleotide dissociation inhibitor (GDI) for a-subunit of heterotrimeric Gi/o protein (Gai/o) and inhibiting the reduction in intracellular cAMP concentration to protect against cell death [13,17,18,19,20,21,22]
The percentages of neurite-bearing cells with at least one neurite longer than 10 lm are summarized in Fig. 2B, which clearly shows that nerve growth factor (NGF) significantly stimulates neurite outgrowth of PC12 cells
Summary
Neuroglobin (Ngb) is a heme protein expressed in the vertebrate brain. We previously engineered a chimeric Ngb protein, in which module M1 of human Ngb is replaced by that of zebrafish Ngb, and showed that the chimeric ZHHH Ngb has a cell membrane-penetrating activity similar to that of zebrafish Ngb and rescues cells from death caused by hypoxia/ reoxygenation as does human Ngb. Addition of chimeric Ngb, but not human or zebrafish Ngb, exogenously to the cell medium induces neurite outgrowth. We prepared several site-directed chimeric Ngb mutants and demonstrated that residues crucial for neurite outgrowth-inducing activity of the chimeric Ngb are not exactly the same as those for its neuroprotective activity. We found that human Ngb binds exclusively to the GDP-bound form of the a-subunits of heterotrimeric Gi/o proteins (Gai/o), which are present in lipid rafts and inhibit adenylate cyclase activity, thereby acting as guanine nucleotide dissociation inhibitor (GDI) for Gai/o and inhibiting the reduction in intracellular cAMP concentration to protect against cell death [13,17,18,19,20,21,22].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
