Dundon Samantha E.R.

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Last Name
Dundon
First Name
Samantha E.R.
ORCID
0000-0001-8032-7975

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  • Article
    FXR1 splicing is important for muscle development and biomolecular condensates in muscle cells
    (Rockefeller University Press, 2020-03-13) Smith, Jean A. ; Curry, Ennessa G. ; Blue, R. Eric ; Roden, Christine ; Dundon, Samantha E.R. ; Rodríguez-Vargas, Anthony ; Jordan, Danielle C. ; Chen, Xiaomin ; Lyons, Shawn M. ; Crutchley, John M. ; Anderson, Paul ; Horb, Marko E. ; Gladfelter, Amy S. ; Giudice, Jimena
    Fragile-X mental retardation autosomal homologue-1 (FXR1) is a muscle-enriched RNA-binding protein. FXR1 depletion is perinatally lethal in mice, Xenopus, and zebrafish; however, the mechanisms driving these phenotypes remain unclear. The FXR1 gene undergoes alternative splicing, producing multiple protein isoforms and mis-splicing has been implicated in disease. Furthermore, mutations that cause frameshifts in muscle-specific isoforms result in congenital multi-minicore myopathy. We observed that FXR1 alternative splicing is pronounced in the serine- and arginine-rich intrinsically disordered domain; these domains are known to promote biomolecular condensation. Here, we show that tissue-specific splicing of fxr1 is required for Xenopus development and alters the disordered domain of FXR1. FXR1 isoforms vary in the formation of RNA-dependent biomolecular condensates in cells and in vitro. This work shows that regulation of tissue-specific splicing can influence FXR1 condensates in muscle development and how mis-splicing promotes disease.
  • Article
    Clustered nuclei maintain autonomy and nucleocytoplasmic ratio control in a syncytium
    (American Society for Cell Biology, 2016-05-18) Dundon, Samantha E.R. ; Chang, Shyr-Shea ; Kumar, Abhishek ; Occhipinti, Patricia ; Shroff, Hari ; Roper, Marcus ; Gladfelter, Amy S.
    Nuclei in syncytia found in fungi, muscles, and tumors can behave independently despite cytoplasmic translation and the homogenizing potential of diffusion. We use a dynactin mutant strain of the multinucleate fungus Ashbya gossypii with highly clustered nuclei to assess the relative contributions of nucleus and cytoplasm to nuclear autonomy. Remarkably, clustered nuclei maintain cell cycle and transcriptional autonomy; therefore some sources of nuclear independence function even with minimal cytosol insulating nuclei. In both nuclear clusters and among evenly spaced nuclei, a nucleus’ transcriptional activity dictates local cytoplasmic contents, as assessed by the localization of several cyclin mRNAs. Thus nuclear activity is a central determinant of the local cytoplasm in syncytia. Of note, we found that the number of nuclei per unit cytoplasm was identical in the mutant to that in wild-type cells, despite clustered nuclei. This work demonstrates that nuclei maintain autonomy at a submicrometer scale and simultaneously maintain a normal nucleocytoplasmic ratio across a syncytium up to the centimeter scale.