摘要:

AbstractThe physiological importance of protein kinase C during oligodendrocyte progenitor maturation was investigated by analyzing the effects of the protein kinase C activator phorbol 12‐myristate 13‐acetate (TPA) on the morphology, proliferation, and differentiation of oligodendrocytes at sequential stages of development. Monoclonal antibodies A2B5 and O4 were used to identify the A2B5+O4−and the A2B5+O4+galactocerebroside−progenitor stages. Anti‐galactocerebroside and anti‐myelin basic protein were used to identify mature, post‐mitotic oligodendrocytes. Proliferation was measured by bromodeoxyuridine incorporation. Within 24 hr after addition, TPA induced a down‐regulation of the O4 antigen in OL progenitors, and an increase of expression of the intermediate filament protein vimentin, leading to a phenotypic reversion from the vimentin−A2B5+O4+phenotype to the less mature vimentin+A2B5+O4−stage. Concomitantly, TPA induced an increase in the number of bromodeoxyuridine‐labeled oligodendrocyte progenitors and extensive process elongation. The response of O4+progenitors was transient. Even with continued exposure to TPA, by 4 days after TPA addition the reverted cells ceased proliferation, reacquired O4 immunoreactivity, became vimentin‐negative, and began to express galactocerebroside and myelin basic protein, and to display the complex, highly branched morphology characteristic of terminally differentiated oligodendrocytes. These results indicate that modulation of protein kinase C activity by TPA induces a transient reversion of O4+progenitors to less mature O4−cells, causing a transient inhibition of terminal differentiation. The relationship of these data to similar responses of the OL lineage to specific growth factors and implications for remyelination after pathologic injury are discusse

ISSN:0360-4012    

DOI:10.1002/jnr.490340112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of peripheral axotomy on the expression of the class III β‐tubulin gene in adult dorsal root ganglion (DRG) neurons was examined. Of the 5 isotypic classes of β‐tubulin expressed in the mammalian nervous system, only the class III β‐tubulin is neuron specific. While information about the expression of several of the tubulin genes during neuronal development and regeneration has become available recently, very little is known about the expression of βIII‐tubulin during axonal regeneration. To explore this issue, we examined axotomy‐induced changes in βIII‐tubulin mRNA levels in adult rat lumbar dorsal root ganglion (DRG) neurons at different times (1–28 days) after unilateral sciatic nerve crush using northern blotting of total RNA and quantitative in situ hybridization. These studies showed an initial decrease in βIII‐tubulin mRNA levels in axotomized DRG neurons as compared to contralateral controls at 1 day after injury followed by robust increases in βIII‐tubulin mRNA levels relative to contralateral controls from 1 to 4 weeks after injury. We postulate that βIII‐tubulin may play an essential role in axonal growth because of its unique neuron‐specific pattern of expression and its substantial increase in neurons that have been stimulated to regrow their

ISSN:0360-4012    

DOI:10.1002/jnr.490340113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWe describe here a new method for transferring genes into cells of the neural tube and neural crest of early avian embryos in vivo. Using the marker genelacZas an example, we infected dissected neural tubes from Hamburger‐Hamilton stage 12–13 quail embryos with a replication‐defective retrovirus carryinglacZduring a 2 hr period of exposure to the virus in culture. Infected neural tubes were then grafted into uninfected host chicken embryos in ovo and, after continued development for several days, the chimeric embryos were processed for β‐galactosidase histochemistry to identify the progeny of infected cells. We show that virus‐infected neural tubes grafted isotopically into the trunk region of host embryos gave rise to cells of both the spinal cord and neural crest. Infected neural crest cells localized within dorsal root ganglia, sympathetic ganglia, peripheral nerves, and within the skin, where they were likely to give rise to melanocytes. These data are consistent with those using other cell marking techniques applied to the neural crest, indicating that retrovirus infection in culture, grafting, and β‐galactosidase expression has a neutral effect on neural crest cell migration and localization. These results indicate the heterospecific grafting of early avian tissues infected with retroviruses carrying foreign genes may be an effective strategy for testing the biological role of various gene products during development. © 1993 W

ISSN:0360-4012    

DOI:10.1002/jnr.490340114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490340101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY