Nuclear-localized Asunder regulates cytoplasmic dynein localization via its role in the Integrator complex

1. Jeanne N. Jodoin^a, Poojitha Sitaram^a, Todd R. Albrecht^b, Sarah B. May^b, Mohammad Shboul^c, Ethan Lee^a, Bruno Reversade^c,^d, Eric J. Wagner^b,¹, and Laura A. Lee^a,¹

Abstract

We previously reported that Asunder (ASUN) is essential for recruitment of dynein motors to the nuclear envelope (NE) and nucleus-centrosome coupling at the onset of cell division in cultured human cells and Drosophila spermatocytes, though the mechanisms underlying this regulation remain unknown. We have also recently identified ASUN as a functional component of Integrator (INT), a multi-subunit complex required for 3’-end processing of small nuclear RNAs (snRNAs). We now provide evidence that ASUN acts in the nucleus in concert with other INT components to mediate recruitment of dynein to the NE. Knockdown of other individual INT subunits in HeLa cells recapitulates the loss of perinuclear dynein in ASUN-siRNA cells. Forced localization of ASUN to the cytoplasm via mutation of its nuclear localization sequence (NLS) blocks its capacity to restore perinuclear dynein in both cultured human cells lacking ASUN and Drosophila asun spermatocytes. Additionally, the levels of several INT subunits are reduced at G2/M when dynein is recruited to the NE, suggesting that INT does not directly mediate this step. Taken together, our data support a model in which a nuclear INT complex promotes recruitment of cytoplasmic dynein to the NE, possibly via a mechanism involving RNA processing.

 

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