Type IV Collagen Controls the Axogenesis of Cerebellar Granule Cells by Regulating Basement Membrane Integrity in Zebrafish

PLoS Genet. 2015 Oct 9;11(10):e1005587. doi: 10.1371/journal.pgen.1005587. eCollection 2015 Oct.


Granule cells (GCs) are the major glutamatergic neurons in the cerebellum, and GC axon formation is an initial step in establishing functional cerebellar circuits. In the zebrafish cerebellum, GCs can be classified into rostromedial and caudolateral groups, according to the locations of their somata in the corresponding cerebellar lobes. The axons of the GCs in the caudolateral lobes terminate on crest cells in the dorsal hindbrain, as well as forming en passant synapses with Purkinje cells in the cerebellum. In the zebrafish mutant shiomaneki, the caudolateral GCs extend aberrant axons. Positional cloning revealed that the shiomaneki (sio) gene locus encodes Col4a6, a subunit of type IV collagen, which, in a complex with Col4a5, is a basement membrane (BM) component. Both col4a5 and col4a6 mutants displayed similar abnormalities in the axogenesis of GCs and retinal ganglion cells (RGCs). Although type IV collagen is reported to control axon targeting by regulating the concentration gradient of an axonal guidance molecule Slit, Slit overexpression did not affect the GC axons. The structure of the BM surrounding the tectum and dorsal hindbrain was disorganized in the col4a5 and col4a6 mutants. Moreover, the abnormal axogenesis of the caudolateral GCs and the RGCs was coupled with aberrant BM structures in the type IV collagen mutants. The regrowth of GC axons after experimental ablation revealed that the original and newly formed axons displayed similar branching and extension abnormalities in the col4a6 mutants. These results collectively suggest that type IV collagen controls GC axon formation by regulating the integrity of the BM, which provides axons with the correct path to their targets.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / metabolism
  • Basement Membrane / growth & development
  • Basement Membrane / metabolism
  • Cerebellum / growth & development
  • Cerebellum / metabolism*
  • Collagen Type IV / genetics*
  • Collagen Type IV / metabolism
  • Extracellular Matrix / genetics
  • Extracellular Matrix / metabolism
  • Nerve Tissue Proteins / genetics
  • Purkinje Cells / metabolism
  • Retinal Ganglion Cells / metabolism*
  • Zebrafish / genetics*
  • Zebrafish / growth & development
  • Zebrafish Proteins / genetics


  • Collagen Type IV
  • Nerve Tissue Proteins
  • Zebrafish Proteins
  • slit1a protein, zebrafish

Grant support

This work was supported by JSPS KAKENHI Grant Number 24370088, 25111709, 26115512 to MH, 25440104 to TS (https://www.jsps.go.jp/english/e-grants/); the Uehara Memorial Foundation to MH (http://www.ueharazaidan.or.jp); Takeda Science Foundation to MH (http://www.takeda-sci.or.jp); and the Naito Foundation to MH (https://www.naito-f.or.jp/en/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.