Expression of neuron-specific tubulin defines a novel population in the proliferative layers of the developing telencephalon

Abstract

We have used a monoclonal antibody against the neuron-specific class III beta-tubulin (TuJ1; Lee et al., 1990b) to study the distribution and morphology of immature neurons in the proliferative ventricular and subventricular zones of the developing telencephalon. Mouse brains from embryonic day 12 (E12) to postnatal day 5 (P5) were fixed either with a non-cross-linking agent, HistoChoice, or with 4% paraformaldehyde, and processed for TuJ1 immunohistochemistry. TuJ1 immunoreactivity first appeared in the proliferative zones of the developing cerebral cortex at E13-E14 as the cortical plate was emerging. After E14, tangentially oriented TuJ1-positive cells were abundant at the interface between the ventricular and subventricular zones. This tangential pattern was less conspicuous in the developing striatum. Within the cortical and striatal ventricular zone TuJ1-positive cells were less numerous and displayed a variety of orientations and morphologies. Postnatally, after the period of neurogenesis has ended, TuJ1 immunoreactivity continued to increase in the subventricular zone and remained high until the last developmental stage examined (P5). Anti-MAP2, another neuron-specific marker, never labeled the cells of the ventricular and subventricular zones, pre- or postnatally. To determine the birthdates of TuJ1-positive cells in the cortical-ventricular and subventricular zones, brains were double labeled with TuJ1 and bromodeoxyuridine according to different pulse-chase schedules. TuJ1-positive cells were postmitotic and generated throughout the period of cortical neurogenesis. Collectively, the results suggest that TuJ1 immunoreactivity distinguishes two neuronal populations: those that remain for an indefinite period of time in the proliferative zones, and those that leave the proliferative zones soon after being generated. Although the fate of the TuJ1-positive cells that reside in the proliferative zones remains unclear, their tangentially aligned orientation and their distribution suggest that they migrate independent of radial glial fibers.

Tissue-specific control of midbody microtubule stability by Citron kinase through modulation of TUBB3 phosphorylation

“…This result was particularly interesting in light of previous studies showing that, in human tumor cells, TUBB3-incorporating microtubules have increased dynamic instability. 35,36 However, although the expression of Tubb3 has been described in some proliferating neuronal precursors of the telencephalon 37,38 and of the spinal cord, 39 this finding would be in apparent contrast with the strongly consolidated view that Tubb3 is a specific marker of postmitotic neurons. Therefore, we asked whether neuronal progenitors could express detectable amounts of Tubb3 protein during mitosis and whether this expression may correlate with neurogenesis.…”

Identification of a developmentally regulated striatum-enriched zinc-finger gene, Nolz-1 , in the mammalian brain

“…The expression of Nolz-1 mRNA was decreased in the differentiated mantle zone. Double labeling showed that Nolz-1-positive cells coexpressed TuJ1, a marker of early differentiating neurons (27), in the SVZ (Fig. 4 I and J), suggesting that Nolz-1 was expressed in early differentiating neurons.…”

Adult bone marrow stromal stem cells express germline, ectodermal, endodermal, and mesodermal genes prior to neurogenesis

“…At 10 days, ␤-III tubulin, an intermediate filament characteristic of mature neurons (Menezes and Luskin, 1994), was present in virtually all cells (Fig. 5B).…”