PMID: 8613790Jan 1, 1996Paper

The molecular composition of neuronal microfilaments is spatially and temporally regulated

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
Ron P WeinbergerP Gunning

Abstract

The actin-based microfilament system is thought to play a critical role in neuronal development. We have determined specific changes in the composition of microfilaments accompanying neuronal morphogenesis. By using specific antibodies against the isoforms for tropomyosin (Tm) (Tm-5 and TmBr-1/-3) and actin (beta- and gamma-actin), we found that during early morphogenesis in vivo immature growing axons contain beta- and gamma-actin and Tm-5. In particular, Tm-5 is exclusively located in the immature axonal processes relative to the neuronal cell body. In contrast, beta-actin and Tm-5 are absent in mature, quiescent axons. This developmental loss from axons is associated with an approximately twofold downregulation of beta-actin and Tm-5 levels in the brain; gamma-actin levels do not change, and this molecule is widely distributed throughout neurons during development. The loss of beta-actin and Tm-5 from axons is accompanied by a progressive appearance of TmBr-1/-3. This apparent replacement of Tm-5 with TmBr-1/-3 occurs over a 2 d time period during rat embryonic hindbrain development and is conserved in evolution between birds and mammals. The loss of Tm-5 from axons involves a redistribution of this molecule to the cell soma...Continue Reading

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