Transcallosal Projections Require Glycoprotein M6-Dependent Neurite Growth and Guidance.

The function of mature neurons critically relies on the developmental outgrowth and projection of their cellular processes. It has long been postulated that the neuronal glycoproteins M6a and M6b are involved in axon growth because these four-transmembrane domain-proteins of the proteolipid protein family are highly enriched on growth cones, but in vivo evidence has been lacking. Here, we report that the function of M6 proteins is required for normal axonal extension and guidance in vivo.

Actin-independent behavior and membrane deformation exhibited by the four-transmembrane protein M6a.

M6a is a four-transmembrane protein that is abundantly expressed in the nervous system. Previous studies have shown that over-expression of this protein induces various cellular protrusions, such as neurites, filopodia, and dendritic spines. In this detailed characterization of M6a-induced structures, we found their varied and peculiar characteristics.

Induction of axon growth arrest without growth cone collapse through the N-terminal region of four-transmembrane glycoprotein M6a.

During development, axons elongate vigorously, carefully controlling their speed, to connect with their targets. In general, rapid axon growth is correlated with active growth cones driven by dynamic actin filaments. For example, when the actin-driven tip is collapsed by repulsive guidance molecules, axon growth is severely impaired.

Proteomics analysis of the temporal changes in axonal proteins during maturation.

After the initial primary projection, axons undergo various structural and functional changes to establish mature neural circuits. The changes in protein expression associated with this maturation were investigated in lateral olfactory tract axons using two-dimensional gel electrophoresis. The most prominent group upregulated during the period consisted of calcium-dependent membrane-binding proteins including VILIP1, neurocalcin delta, copine 6, and annexin A6 from three structurally different families.

The effect of tert-butylhydroquinone-induced oxidative stress in MDBK cells using XTT assay: implication of tert-butylhydroquinone-induced NADPH generating enzymes.

Tetrazolium salts such as XTT and MTT are widely used to produce formazan for cell proliferation and cytotoxicity assays through bioreductase activity. However, the XTT assay showed significant increase in MDBK cell viability when cells were treated with both 50 and 100 muM of the pro-oxidant, tert-butylhydroquinone (t-BHQ), although the crystal violet assay showed no cytotoxic effect with these concentrations, and the induction of lipid peroxidation was not observed. We investigated the mechanism of enhancement of XTT substrate reduction after treatment of MDBK cells with t-BHQ, leading to apparent increase in cell viability.