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DNA Damage and Base Excision Repair; An Important Role during Zebrafish Embryogenesis.

紀錄類型:	書目-語言資料,手稿 : Monograph/item
正題名/作者:	DNA Damage and Base Excision Repair; An Important Role during Zebrafish Embryogenesis./
作者:	Moore, Stephen Paul Gifford.
面頁冊數:	1 online resource (98 pages)
附註:	Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.
標題:	Biology. -
電子資源:	click for full text (PQDT)
ISBN:	9780355511840

DNA Damage and Base Excision Repair; An Important Role during Zebrafish Embryogenesis.
Moore, Stephen Paul Gifford.

DNA Damage and Base Excision Repair; An Important Role during Zebrafish Embryogenesis. - 1 online resource (98 pages)

Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.

Thesis (Ph.D.)--Northeastern University, 2017.

Includes bibliographical references

Damage to DNA is an unavoidable consequence of life. Unrepaired DNA damage is mutagenic, promotes genomic instability, and leads to the onset of numerous serious diseases. Multiple pathways have evolved to repair specific types of DNA damage. Of these, the multi-enzyme base excision repair (BER) pathway is considered the most active, because BER repairable damage is ongoing. Embryogenesis is a highly complex and regulated process. Since developing embryonic cells divide rapidly, unrepaired DNA damage leads to mutation and cell death. Many BER enzymes are embryonic lethal as knockouts, but not in adult cell cultures. This indicates an important role during embryonic development. Active DNA demethylation of 5-methylcytosine (5mC) in CpG islands during embryogenesis may result in DNA damage requiring BER. AP endonuclease (Apex1) is an essential BER enzyme. It incises abasic (AP) sites resulting from removal of DNA lesions by DNA glycosylases, allowing subsequent repair. Accumulation of AP sites is toxic. Knockdown (K/D) of Apex1 in zebrafish embryos results in a consistent and concurrent loss of the critical transcription factor (TF) Creb1. Many Creb1 dependent genes are subsequently perturbed resulting in abnormal embryo development. Death occurs at ~7 days post fertilization (7dpf). Research in this dissertation shows that DNA damage increases in zebrafish embryos at the mid-blastula transition (MBT) when zygotic genome activation (ZGA) occurs. Damage is further elevated with Apex1 K/D, thereby illustrating the importance of fully functional BER during embryonic development. Furthermore, increased DNA damage inversely correlates with decreased levels of 5mC and vice versa, providing indirect evidence that active DNA demethylation is at least one source of elevated embryonic DNA damage. The Creb1 binding site (CRE site [TGACGTCA]) is present within the promoter CpG island of the creb1 gene and some 5000 other genes. It is likely that active DNA demethylation of the Creb1 promoter may also affect the CRE site CpG dinucleotide. My published work shows that binding of recombinant CREB1 to the CRE site is modulated by DNA damage, and abolished by 5mC in the CpG. We also find that both recombinant CREB1 and BER glycosylases compete when DNA damage occurs within a TFs binding sequence, and demonstrably affects embryo development. These novel findings provide insight into the presence, timing, and potential source of DNA damage during zebrafish embryogenesis. They also show how DNA damage may act in an epigenetic fashion when it occurs in a TF binding site, and that these results are valid both in vitro and in vivo. We speculated that BER substrates act in an epigenetic fashion.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780355511840Subjects--Topical Terms:

599573
Biology.
Index Terms--Genre/Form:

554714
Electronic books.

DNA Damage and Base Excision Repair; An Important Role during Zebrafish Embryogenesis.
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500 $a Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.
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502 $a Thesis (Ph.D.)--Northeastern University, 2017.
504 $a Includes bibliographical references
520 $a Damage to DNA is an unavoidable consequence of life. Unrepaired DNA damage is mutagenic, promotes genomic instability, and leads to the onset of numerous serious diseases. Multiple pathways have evolved to repair specific types of DNA damage. Of these, the multi-enzyme base excision repair (BER) pathway is considered the most active, because BER repairable damage is ongoing. Embryogenesis is a highly complex and regulated process. Since developing embryonic cells divide rapidly, unrepaired DNA damage leads to mutation and cell death. Many BER enzymes are embryonic lethal as knockouts, but not in adult cell cultures. This indicates an important role during embryonic development. Active DNA demethylation of 5-methylcytosine (5mC) in CpG islands during embryogenesis may result in DNA damage requiring BER. AP endonuclease (Apex1) is an essential BER enzyme. It incises abasic (AP) sites resulting from removal of DNA lesions by DNA glycosylases, allowing subsequent repair. Accumulation of AP sites is toxic. Knockdown (K/D) of Apex1 in zebrafish embryos results in a consistent and concurrent loss of the critical transcription factor (TF) Creb1. Many Creb1 dependent genes are subsequently perturbed resulting in abnormal embryo development. Death occurs at ~7 days post fertilization (7dpf). Research in this dissertation shows that DNA damage increases in zebrafish embryos at the mid-blastula transition (MBT) when zygotic genome activation (ZGA) occurs. Damage is further elevated with Apex1 K/D, thereby illustrating the importance of fully functional BER during embryonic development. Furthermore, increased DNA damage inversely correlates with decreased levels of 5mC and vice versa, providing indirect evidence that active DNA demethylation is at least one source of elevated embryonic DNA damage. The Creb1 binding site (CRE site [TGACGTCA]) is present within the promoter CpG island of the creb1 gene and some 5000 other genes. It is likely that active DNA demethylation of the Creb1 promoter may also affect the CRE site CpG dinucleotide. My published work shows that binding of recombinant CREB1 to the CRE site is modulated by DNA damage, and abolished by 5mC in the CpG. We also find that both recombinant CREB1 and BER glycosylases compete when DNA damage occurs within a TFs binding sequence, and demonstrably affects embryo development. These novel findings provide insight into the presence, timing, and potential source of DNA damage during zebrafish embryogenesis. They also show how DNA damage may act in an epigenetic fashion when it occurs in a TF binding site, and that these results are valid both in vitro and in vivo. We speculated that BER substrates act in an epigenetic fashion.
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