Anti-MTG16 antibodies reveal MTG16 subcellular distribution and nucleocytoplasmic transport in erythroleukemia cells

Abstract:

The myeloid translocation gene (MTG) family of transcriptional corepressors consists of three highly conserved members: MTG8, MTG16, and MTGR1, each evolutionarily related to the Drosophila protein NERVY and with orthologs across the mammalian hierarchy. By coordinating coincident interactions between DNA binding proteins, other corepressors, and epigenetic effectors, MTG proteins occupy a critical nexus in transcriptional control complexes to profoundly impact the specification of cell fate. MTG family members are most conserved within nervy homology regions (NHRs) 1–4, with each region fulfilling functions common to the family. Studies of functional differences between MTG proteins require carefully qualified immunologic reagents specific to each family member. We have developed a group of a-MTG16 antibodies and carefully characterized their specificity for MTG16. These tools reveal that MTG16 is concentrated in the cytoplasm of erythroleukemia cell lines from human and mouse. Using the chromosome region maintenance 1 (CRM1) antagonist leptomycin B, we show that MTG16 levels rise in the nucleus of murine erythroleukemia cells and decline in the cytoplasm. Together, these data indicate bidirectional movement of MTG16 between cytoplasmic and nuclear compartments. Our work reveals an unrecognized feature of MTG16 regulation that may impact cell fate specification and provides reagents to address important questions regarding MTG16 functions in vivo.

Keywords::

• antibody
• nucleus
• cytoplasm
• transport

Acknowledgments

The authors are indebted to colleagues Jason Singer, Don Ayer, and Mahesh Chandrasekharan for critical review and helpful suggestions regarding the manuscript. We gratefully acknowledge support from the oligonucleotide synthesis and DNA sequencing core facilities of the University of Utah and the Huntsman Cancer Institute. This work was supported by grants from the National Institutes of Health (K08 DK080190) and generous support from the St Baldrick’s Foundation and Hyundai Hope on Wheels Foundation.

Disclosure

Other than the funding support received (outlined in the Acknowledgments), the authors declare no conflicts of interest in this work.