Indian hedgehog B function is required for the specification of oligodendrocyte progenitor cells in the zebrafish CNS.
A subset of ventral spinal cord precursors, known as pMN precursor cells, initially generate motor neurons and then oligodendrocyte progenitor cells (OPCs), which migrate and differentiate as myelinating oligodendrocytes in the developing neural tube. The switch between motor neuron and oligodendrocyte production by the pMN neural precursors is an important step in building a functional nervous system. However, the precise mechanism that orchestrates the sequential generation of motor neurons and oligodendrocytes within the common population of pMN precursors is still unclear. The current study demonstrates that Indian Hedgehog b (Ihhb), previously known as Echidna Hedgehog, begins to be expressed in the floor plate cells of the ventral spinal cord at the time of OPC specification in zebrafish embryos. Ihhb loss-of-function analysis revealed that Ihhb function is required for OPC specification from pMN precursors by negatively regulating the proliferation of neural precursors. Finally, results showed that Sonic Hedgehog (Shh) could not replace Ihhb function in OPC specification, suggesting that Ihhb and Shh play separate roles in OPC specification. Altogether, data from the present study suggested a novel mechanism, mediated by Ihhb, for the sequential generation of motor neurons and oligodendrocytes from pMN precursors in the ventral spinal cord of zebrafish embryos.
Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea.
Ah-Young
AY
Chung
Suhyun
S
Kim
Eunmi
E
Kim
Dohyun
D
Kim
Inyoung
I
Jeong
Young Ryun
YR
Cha
Young-ki
YK
Bae
Seung Woo
SW
Park
Jehee
J
Lee
Hae-Chul
HC
Park
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002469:Cell Separation; D053823:Hedgehog Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D009046:Motor Neurons / Q000166:cytology / Q000378:metabolism; D055495:Neurogenesis / Q000502:physiology*; D009836:Oligodendroglia / Q000166:cytology* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000378:metabolism*
D053823:Hedgehog Proteins; D029961:Zebrafish Proteins; C509233:ihhb protein, zebrafish