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Kiel Tietz Dissertation.pdf (30.23 MB)

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Investigating the Rapid Clearance of Oscillating Transcripts during Vertebrate Segmentation

Tietz, Kiel Thomas
http://rave.ohiolink.edu/etdc/view?acc_num=osu1555604080595922

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Molecular, Cellular and Developmental Biology.
Vertebrate segmentation is regulated by the segmentation clock, a biological oscillator that controls periodic formation of embryonic segments. This molecular oscillator generates cyclic gene expression in the tissue that generates somites and has the same periodicity as somite formation. Molecular components of the clock include the Hes/her family of transcriptional repressors, but additional transcripts also cycle. Maintenance of oscillatory gene expression requires that transcriptional activation and repression, RNA turnover, translation, and protein degradation are rapid (one cycle is 30 minutes in the zebrafish). Little is known about post-transcriptional control of cyclic transcripts during somitogenesis and my work employs genetic and biochemical approaches to better understand rapid cyclic transcript turnover. The lab previously isolated a zebrafish segmentation clock mutant, tortuga, that has elevated levels of cyclic transcripts. Loss of proline-rich nuclear receptor coactivator protein Pnrc2 is responsible for cyclic transcript accumulation in tortuga deletion mutants and a new pnrc2 loss-of-function mutant displays an identical phenotype (Chapter 2). The her1 3’UTR confers instability to otherwise stable transcripts in a Pnrc2-dependent manner indicating that the 3’UTR of cyclic transcripts is critical for Pnrc2-mediated decay. Interestingly, cyclic protein levels do not accumulate in pnrc2-deficient embryos, suggesting that stabilized cyclic transcripts are not efficiently translated and that translation may be controlled by an additional post-transcriptional mechanism. Together, these findings demonstrate Pnrc2 regulates cyclic transcript turnover though 3’UTR interactions and suggests another level of post-transcriptional regulation maintains proper oscillations of cyclic genes in pnrc2 mutants during somitogenesis. To identify her1 3’UTR cis-regulatory elements critical for Pnrc2-mediated decay (Chapter 3), I show the last 179 nucleotides of the 725 nt her1 3’UTR is sufficient and necessary to confer Pnrc2-dependent rapid instability to reporter transcripts. Additionally, I show the 3’UTR of the deltaC (dlc) cyclic transcript also confers Pnrc2-mediated decay. I hypothesize that mechanisms regulating cyclic transcript turnover are shared among cyclic transcripts and have identified two putative decay-inducting motifs that are present in the destabilizing 179 nt region of the her1 3’UTR and are conserved in the dlc 3’UTR, a Pumilio response element (PRE) and a AU-rich element (ARE). I show here the PRE and ARE of the her1 3’UTR functions in the turnover of reporter transcripts. These results suggest Pnrc2 may function with Pumilio, a known decay factor, to regulate the rapid turnover of cyclic transcripts during somitogenesis. My work explores mechanisms regulating oscillation dynamics during vertebrate segmentation and will further our understanding of pathways that control post-transcriptional gene regulation.
Sharon Amacher (Advisor)
Susan Cole (Committee Member)
Guramrit Singh (Committee Member)
James Jontes (Committee Member)
175 p.
Developmental Biology; Genetics; Molecular Biology
her; dlc; RNA decay; Pumilio response element; AU-rich element; somitogenesis; oscillatory expression

Recommended Citations

Citations

  • Tietz, K. T. (2019). Investigating the Rapid Clearance of Oscillating Transcripts during Vertebrate Segmentation [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555604080595922

    APA Style (7th edition)

  • Tietz, Kiel. Investigating the Rapid Clearance of Oscillating Transcripts during Vertebrate Segmentation. 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1555604080595922.

    MLA Style (8th edition)

  • Tietz, Kiel. "Investigating the Rapid Clearance of Oscillating Transcripts during Vertebrate Segmentation." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555604080595922

    Chicago Manual of Style (17th edition)

osu1555604080595922
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This open access ETD is published by The Ohio State University and OhioLINK.