Wu You Kure, Fujishima Kazuto, Kengaku Mineko
Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, Japan.
PLoS One. 2015 Feb 23;10(2):e0118482. doi: 10.1371/journal.pone.0118482. eCollection 2015.
Hippocampal pyramidal cells and dentate granule cells develop morphologically distinct dendritic arbors, yet also share some common features. Both cell types form a long apical dendrite which extends from the apex of the cell soma, while short basal dendrites are developed only in pyramidal cells. Using quantitative morphometric analyses of mouse hippocampal cultures, we evaluated the differences in dendritic arborization patterns between pyramidal and granule cells. Furthermore, we observed and described the final apical dendrite determination during dendritic polarization by time-lapse imaging. Pyramidal and granule cells in culture exhibited similar dendritic patterns with a single principal dendrite and several minor dendrites so that the cell types were not readily distinguished by appearance. While basal dendrites in granule cells are normally degraded by adulthood in vivo, cultured granule cells retained their minor dendrites. Asymmetric growth of a single principal dendrite harboring the Golgi was observed in both cell types soon after the onset of dendritic growth. Time-lapse imaging revealed that up until the second week in culture, final principal dendrite designation was not stabilized, but was frequently replaced by other minor dendrites. Before dendritic polarity was stabilized, the Golgi moved dynamically within the soma and was repeatedly repositioned at newly emerging principal dendrites. Our results suggest that polarized growth of the apical dendrite is regulated by cell intrinsic programs, while regression of basal dendrites requires cue(s) from the extracellular environment in the dentate gyrus. The apical dendrite designation is determined from among multiple growing dendrites of young developing neurons.
海马锥体细胞和齿状颗粒细胞发育出形态上不同的树突分支，但也有一些共同特征。这两种细胞类型都形成一条从细胞体顶端延伸的长顶树突，而短的基底树突仅在锥体细胞中发育。通过对小鼠海马培养物进行定量形态测量分析，我们评估了锥体细胞和颗粒细胞之间树突分支模式的差异。此外，我们通过延时成像观察并描述了树突极化过程中最终顶树突的确定。培养中的锥体细胞和颗粒细胞表现出相似的树突模式，有一条主要树突和几条次要树突，因此从外观上不容易区分细胞类型。虽然颗粒细胞中的基底树突在成年体内通常会退化，但培养的颗粒细胞保留了它们的次要树突。在树突生长开始后不久，在这两种细胞类型中都观察到含有高尔基体的单一主要树突的不对称生长。延时成像显示，直到培养的第二周，最终主要树突的指定才稳定下来，而是经常被其他次要树突取代。在树突极性稳定之前，高尔基体在细胞体内动态移动，并在新出现的主要树突处反复重新定位。我们的结果表明，顶树突的极化生长受细胞内在程序调控，而基底树突的退化需要来自齿状回细胞外环境的线索。顶树突的指定是从年轻发育神经元的多个生长树突中确定的。
