Postnatal development of cerebellar zones revealed by neurofilament heavy chain protein expression

Joshua J White,Roy V Sillitoe

doi:10.3389/fnana.2013.00009

Abstract

The cerebellum is organized into parasagittal zones that control sensory-motor behavior. Although the architecture of adult zones is well understood, very little is known about how zones emerge during development. Understanding the process of zone formation is an essential step toward unraveling how circuits are constructed to support specific behaviors. Therefore, we focused this study on postnatal development to determine the spatial and temporal changes that establish zonal patterns during circuit formation. We used a combination of wholemount and tissue section immunohistochemistry in mice to show that the cytoskeletal protein neurofilament heavy chain (NFH) is a robust marker for postnatal cerebellar zonal patterning. The patterned expression of NFH is initiated shortly after birth, and compared to the domains of several known zonal markers such as zebrin II, HSP25, neurogranin, and phospholipase Cβ4 (PLCβ4), NFH does not exhibit transient expression patterns that are typically remodeled between stages, and the adult zones do not emerge after a period of uniform expression in all lobules. Instead, we found that throughout postnatal development NFH gradually reveals distinct zones in each cerebellar lobule. The boundaries of individual NFH zones sharpen over time, as zones are refined during the second and third weeks after birth. Double labeling with neurogranin and PLCβ4 further revealed that although the postnatal expression of NFH is spatially and temporally unique, its pattern of zones respects a fundamental and well-known molecular topography in the cerebellum. The dynamics of NFH expression support the hypothesis that adult circuits are derived from an embryonic map that is refined into zones during the first 3-weeks of life.

Highlights

The adult cerebellum is comprised of relatively few cell types that are found, with only few exceptions, throughout all ten of its lobules (Larsell, 1952; Altman and Bayer, 1997; Mugnaini et al, 2011)
Because the phosphorylated form is primarily expressed in axons, we used the non-phosphorylated form to investigate cerebellar architecture because it is heavily expressed in somata, dendrites, and axons (Marc and Clavel, 1986), and because it marks Purkinje cell zones in the adult cerebellum (Sillitoe et al, 2008; Demilly et al, 2011)
neurofilament heavy chain (NFH) EXPRESSION REVEALS A CONSISTENT ARRAY OF ZONES THROUGHOUT POSTNATAL DEVELOPMENT We examined the cerebellum at several key stages during postnatal development to gain a better understanding of how zones resolve during circuit formation

Summary

INTRODUCTION

The adult cerebellum is comprised of relatively few cell types that are found, with only few exceptions, throughout all ten of its lobules (Larsell, 1952; Altman and Bayer, 1997; Mugnaini et al, 2011). At all stages examined NFH expression clearly delineates zones in all lobules of the vermis and in the hemispheres These data suggest that despite the dynamic morphogenetic patterning that transforms embryonic clusters to adult zones (Larouche et al, 2006; Fujita et al, 2012), a stable map of sagittal compartments may link cerebellar development to adult function. Such a map might be essential for guiding circuit connectivity and perhaps provide a fundamental scaffold upon which synaptic pruning and plasticity shape sensory-motor circuits

METHODS

RESULTS

DISCUSSION