# A non-transcriptional mitotic function of POU/Oct factors ensures spindle assembly and chromosome segregation

## TL;DR

This study shows that POU/Oct proteins help ensure proper cell division by stabilizing spindles and chromosomes, independent of their usual role in gene regulation.

## Contribution

The study reveals a non-transcriptional role of POU/Oct factors in mitotic spindle assembly and chromosome segregation.

## Key findings

- Nub and POU2F1 are essential for spindle stability and accurate chromosome segregation during mitosis.
- Nub recruitment to spindles is independent of DNA binding and depends on microtubules and motor proteins.
- POU/Oct factors have dual roles in the cell cycle, acting in mitosis and interphase through different mechanisms.

## Abstract

The POU family, also known as Oct, of transcription factors (POU/Oct), are crucial regulators of cellular processes, including proliferation, cell fate determination, and cancer. Despite their importance, the specific molecular mechanisms by which they influence cell division remain largely unclear. Here, we show that Nub (also known as Pdm1), a Drosophila homolog of human POU2F1 (also known as Oct1), is essential for accurate mitotic progression in a non-transcriptional manner. Live imaging and immunostaining in Drosophila syncytial embryos reveal that its depletion leads to disorganized spindles, aberrant chromosome segregation and delayed mitotic progression. Similarly, reduction of POU2F1 in live human cells caused disorganized mitotic spindles and spindle collapse. Nub is enriched within the mitotic spindles, and this recruitment is independent of its sequence-specific DNA binding. Instead, it depends on the integrity of spindle microtubules and is regulated by mitosis-related motor proteins, and kinases. Our findings identify both fly Nub and human POU2F1 as important regulators of mitotic progression, acting to maintain spindle stability and proper elongation. The non-transcriptional mitotic role of Nub reveals a previously unrecognized mechanism of POU/Oct proteins and provides new insight into their potential oncogenic properties.

Highlighted Article:
Using high-resolution live-imaging, we show that POU/Oct factors play dual roles during the cell cycle, providing accuracy in mitosis and chromosome segregation independently of their transcriptional functions during interphase.