Identification of Juxtanodin promoter and its transcriptional regulation during the ATRA-induced differentiation of C6 cells. Mol Cell Biochem. 2011;350:177-183. [PMID: 21221725 DOI: 10.1007/s11010-010-0696-y]

A higher proportion of ermin-immunopositive oligodendrocytes in areas of remyelination

Incomplete remyelination is frequent in multiple sclerosis (MS)-lesions, but there is no established marker for recent remyelination. We investigated the role of the oligodendrocyte/myelin protein ermin in de- and remyelination in the cuprizone (CPZ) mouse model, and in MS. The density of ermin+ oligodendrocytes in the brain was significantly decreased after one week of CPZ exposure (p < 0.02). The relative proportion of ermin+ cells compared to cells positive for the late-stage oligodendrocyte marker Nogo-A increased at the onset of remyelination in the corpus callosum (p < 0.02). The density of ermin-positive cells increased in the corpus callosum during the CPZ-phase of extensive remyelination (p < 0.0001). In MS, the density of ermin+ cells was higher in remyelinated lesion areas compared to non-remyelinated areas both in white- (p < 0.0001) and grey matter (p < 0.0001) and compared to normal-appearing white matter (p < 0.001). Ermin immunopositive cells in MS-lesions were not immunopositive for the early-stage oligodendrocyte markers O4 and O1, but a subpopulation was immunopositive for Nogo-A. The data suggest a relatively higher proportion of ermin immunopositivity in oligodendrocytes compared to Nogo-A indicates recent or ongoing remyelination.

Ermin is a p116RIP -interacting protein promoting oligodendroglial differentiation and myelin maintenance

Myelin sheaths, which insulate the axons and ensure saltatory conduction of the nerve impulse, are generated and maintained via largely uncharacterized mechanisms. Ermin is an oligodendrocyte-specific protein associated with the cytoskeleton, but how it regulates cytoskeletal remodeling during oligodendrocyte differentiation and its role in myelin maintenance are not clear. To address this, we generated mice constitutively deficient for Ermn, the Ermin-coding gene. We found that aged Ermn-knockout mice exhibit an aberrant myelin architecture, with splitting of myelin layers, peeling of the myelin sheath from axons, and breakdown of myelinated fibers. As a result, these mice had remarkably impaired motor coordination. Ermn knockout also accelerated cuprizone-induced demyelination and exacerbated the associated movement disorders. Ermin was found to contribute to oligodendrocyte morphogenesis by associating with the myosin phosphatase Rho interacting protein (Mprip/p116^RIP ) and inactivating RhoA, a GTPase that controls cytoskeletal rearrangement in differentiating cells. These findings provide novel insights into the mechanisms regulating oligodendroglial differentiation, the maintenance of the myelin sheaths, and remyelination.

Effect of all-trans retinoic acid on the differentiation, invasion and metastasis of liver cancer HepG2 cells

AIM: To investigate the effect of all-trans retinoic acid (ATRA) on the differentiation, invasion and metastasis of liver cancer HepG2 cells.

METHODS: After HepG2 cells were treated with different concentrations of ATRA, the proliferation of HepG2 cells was evaluated by MTT assay; anchorage-dependent growth was evaluated by colony formation assay; AFP secretion was determined by ELISA; the transcription levels of Nanog and MMP-9 were assessed by RT-PCR, and their protein levels were assessed by Western blot; and cell invasion and migration were evaluated by scratch test and transwell assay.

RESULTS: ATRA suppressed the proliferation and anchorage-dependent growth of HepG2 in a dose- and time-dependent manner. ATRA induced cell differentiation and decreased AFP secretion in HepG2 cells (both P < 0.05). Treatment with ATRA down-regulated the mRNA and protein levels of Nanog and MMP-9 (within 24 hours) in a dose- and time-dependent manner. In addition, ATRA could inhibit the invasion and metastasis of HepG2 cells.

CONCLUSION: ATRA may induce cell differentiation, reduce cell invasion and migration and down-regulate the levels of Nanog in HepG2 cells.