During cell division, the spindle apparatus pulls away the chromatides. The orientation of the spindle has an influence, whether the same cell type as the mother cell develops or whether the cells differntiate into another cell type.
 
Two research groups of the IMBA led by Daniel Gerlich and IMBA  vice director Jürgen Knoblich have now detected a molecular mechanism, Which indicates the correct direction to the spindle apparatus. The molecular mechanism consists of small ribonucleic acids, the so-called MiR-34/449. According to the research results of a working group located in Göttingen, micro-RNAs of the family miR-34/449 have an influence on the cell fate by influencing the p53 signal pathway thus protecting the cells from uncontrolled cell division and tumor formation. A deletion of the miR-449 locus promoted the reprogramming of somatic cells into pluripotent stem cells.
 
In order to investigate the influence of the spindle mechanism on the malformation of a developing brain, the researchers from Vienna observed nerve stem cells during its division. They tagged the spindle apparatus in cell cultures and found that the miR-34/449 influenced the spindle apparatus during the division. If miR-34/449 was blocked, the spindle apparatus did not attach at the right site. Although it divided the cells into two equal baseline cell types, but the cells did not differentiate further into nerve or glial cells.

Disorders of this mechanism can lead to malformations of the brain.

Original publication is released in the EMBO Journal:
Juan Pablo Fededa, Christopher Esk, Beata Mierzwa, Rugile Stanyte, Shuiqiao Yuan, Huili Zheng, Klaus Ebnet, Wei Yan, Juergen A Knoblich, Daniel W Gerlich (2016): MicroRNA-34/449 controls withotic spindle orientation during mammalian cortex development. The EMBO Journal,
DOI: 10.15252 / embj.201694056

Source:
https://idw-online.de/en/news663053