Id3 upregulates BrdU incorporation associated with a DNA damage response, not replication, in human pancreatic β-cells

Lee, Seung‐Hee; Hao, Ergeng; Levine, Fred; Itkin-Ansari, Pamela

doi:10.4161/isl.3.6.17923

Cited by 24 publications

(22 citation statements)

References 82 publications

(104 reference statements)

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“…Recent studies have demonstrated increased apoptotic rates that correspond with increased BrdU or 3 H-thymidine incorporation rates. [24][25][26] In contrast, our phosphorylated histone gH2AX data demonstrates that AURKA does not result in enhanced b-cell apoptosis levels. As AURKA is a downstream target of Nkx6.1, it is important to point out that these data correspond with recent findings that overexpression of Nkx6.1 or Pdx1 result in increased b-cell proliferation without enhancing apoptosis rates.…”

Section: 1229contrasting

confidence: 61%

“…Overexpression of the transcription factors HNF4a and Id3 were shown to upregulate DNA replication by BrdU incorporation, however they also observed an elevated rate of phosphorylated histone gH2AX staining. 24,25 In addition, a recent study demonstrated that a gain of function mutation of glucokinase results in increased b-cell proliferation that corresponds with increased apoptosis rates. 26 To determine the effect of AURKA overexpression on b-cell apoptosis rates, we measured the percentage of phosphorylated histone gH2AX positive primary rat islet b-cells.…”

Section: Aurka Does Not Increase Apoptosis Rates In Primary Rat B-cellsmentioning

confidence: 99%

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Aurora Kinase A is critical for the Nkx6.1 mediated β-cell proliferation pathway

Hobson

Draney

Stratford

et al. 2015

Islets

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Type 1 and type 2 diabetes are ultimately characterized by depleted b-cell mass. Characterization of the molecular pathways that control b-cell proliferation could be harnessed to restore these cells. The homeobox b-cell transcription factor Nkx6.1 induces b-cell proliferation by activating the orphan nuclear receptors Nr4a1 and Nr4a3. Here, we demonstrate that Nkx6.1 localizes to the promoter of the mitotic kinase AURKA (Aurora Kinase A) and induces its expression. Adenovirus mediated overexpression of AURKA is sufficient to induce proliferation in primary rat islets while maintaining glucose stimulated insulin secretion. Furthermore, AURKA is necessary for Nkx6.1 mediated b-cell proliferation as demonstrated by shRNA mediated knock down and pharmacological inhibition of AURKA kinase activity. AURKA preferentially induces DNA replication in b-cells as measured by BrdU incorporation, and enhances the rate of histone H3 phosphorylation in primary b-cells, demonstrating that AURKA induces the replicative and mitotic cell cycle phases in rat b-cells. Finally, overexpression of AURKA results in phosphorylation of the cell cycle regulator p53, which targets p53 for degradation and permits cell cycle progression. These studies define a pathway by which AURKA upregulation by Nkx6.1 results in phosphorylation and degradation of p53, thus removing a key inhibitory factor and permitting engagement of the b-cell proliferation pathway.

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Section: 1229contrasting

confidence: 61%

Section: Aurka Does Not Increase Apoptosis Rates In Primary Rat B-cellsmentioning

confidence: 99%

Aurora Kinase A is critical for the Nkx6.1 mediated β-cell proliferation pathway

Hobson

Draney

Stratford

et al. 2015

Islets

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“…The other clones, which had no previously identified association with MDC1, encoded ID3 (NM_002167), PIAS1 (NM_016166), UBE2I (NM_194259), KPNA2 (NM_0022266), ZNF114 (NM_153608), KIFC1 (NM_002263), CASP8AP2 (NM_001137667), C2orf44 (NM_025203), SRSF11 (NM_001190987), TINP1 (NM_014886), GPRC5C (NM_022036), and WWC1 (NM_015238). Among these, DNA-binding protein inhibitor ID3 was particularly notable because this HLH-containing protein has been shown to activate a DNA repair process 18 and, correspondingly, when ID3 is inactivated, excess DNA damage accumulates 19 .…”

Section: Resultsmentioning

confidence: 99%

ID3 regulates the MDC1-mediated DNA damage response in order to maintain genome stability

et al. 2017

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MDC1 plays a critical role in the DNA damage response (DDR) by interacting directly with several factors including γ-H2AX. However, the mechanism by which MDC1 is recruited to damaged sites remains elusive. Here, we show that MDC1 interacts with a helix–loop–helix (HLH)-containing protein called inhibitor of DNA-binding 3 (ID3). In response to double-strand breaks (DSBs) in the genome, ATM phosphorylates ID3 at serine 65 within the HLH motif, and this modification allows a direct interaction with MDC1. Moreover, depletion of ID3 results in impaired formation of ionizing radiation (IR)-induced MDC1 foci, suppression of γ-H2AX-bound MDC1, impaired DSB repair, cellular hypersensitivity to IR, and genomic instability. Disruption of the MDC1–ID3 interaction prevents accumulation of MDC1 at sites of DSBs and suppresses DSB repair. Thus, our study uncovers an ID3-dependent mechanism of recruitment of MDC1 to DNA damage sites and suggests that the ID3–MDC1 interaction is crucial for DDR.

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“…Some agents that stimulate islet cell proliferation can simultaneously damage islets by causing impairment of glucose-stimulated insulin secretion (GSIS), decreased insulin content, or activation of DNA damage and programmed cell death (5,25,26). These effects have not been observed when Pdx-1 or Nkx6.1 overexpression is used to activate islet cell replication (9-12), but it remains possible that Inhbb or activin B treatment could have (Table 1) was studied further by RT-PCR and overexpression.…”

Section: Fig 5 Pdx-1 Produces a Soluble Factor(s) That Stimulates Ratmentioning

confidence: 99%

A Pdx-1-Regulated Soluble Factor Activates Rat and Human Islet Cell Proliferation

Hayes

Zhang

Becker

et al. 2016

Molecular and Cellular Biology

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The homeodomain transcription factor Pdx-1 has important roles in pancreas and islet development as well as in ␤-cell function and survival. We previously reported that Pdx-1 overexpression stimulates islet cell proliferation, but the mechanism remains unclear. Here, we demonstrate that overexpression of Pdx-1 triggers proliferation largely by a non-cell-autonomous mechanism mediated by soluble factors. Consistent with this idea, overexpression of Pdx-1 under the control of a ␤-cell-specific promoter (rat insulin promoter [RIP]) stimulates proliferation of both ␣ and ␤ cells, and overexpression of Pdx-1 in islets separated by a Transwell membrane from islets lacking Pdx-1 overexpression activates proliferation in the untreated islets. Microarray and gene ontology (GO) analysis identified inhibin beta-B (Inhbb), an activin subunit and member of the transforming growth factor ␤ (TGF-␤) superfamily, as a Pdx-1-responsive gene. Overexpression of Inhbb or addition of activin B stimulates rat islet cell and ␤-cell proliferation, and the activin receptors RIIA and RIIB are required for the full proliferative effects of Pdx-1 in rat islets. In human islets, Inhbb overexpression stimulates total islet cell proliferation and potentiates Pdx-1-stimulated proliferation of total islet cells and ␤ cells. In sum, this study identifies a mechanism by which Pdx-1 induces a soluble factor that is sufficient to stimulate both rat and human islet cell proliferation.T ype 1 and type 2 diabetes ultimately arise from loss of functional islet ␤-cell mass (1-3). Islet transplantation and pharmaceutical activation of ␤-cell regeneration have been considered strategies for treatment of these diseases, but both approaches are hindered by the lack of druggable pathways that reliably induce human ␤-cell replication (4). Furthermore, factors that induce ␤-cell growth must do so without altering key ␤-cell functions, such as glucose-stimulated insulin secretion (GSIS), or causing cellular or DNA damage (5). For example, overexpression of cyclin D or cyclin-dependent kinase 6 (CDK6) induces human ␤-cell proliferation with retention of function (6) but leads to DNA damage, as measured by staining for ␥-H2A member histone family member X (␥-H2AX) (5).Our laboratory has demonstrated that Pdx-1 and Nkx6.1, two homeobox domain transcription factors well known for key roles in islet ␤-cell development, activate proliferation when overexpressed in rat or human islets while maintaining and enhancing GSIS, respectively (7-10). Importantly, the increase in proliferation induced by either factor has little to no impact on ␥-H2AX expression, suggesting that these factors engage "safe" pathways of islet cell replication. In adult islets, Pdx-1 expression is restricted to ␤ and ␦ cells, and Nkx6.1 expression is restricted to ␤ cells. Importantly, expression of these transcription factors is low or absent in nonislet cells, except in the central nervous system, suggesting that deeper knowledge of the molecular pathways that they activate might be an entrée to...

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Id3 upregulates BrdU incorporation associated with a DNA damage response, not replication, in human pancreatic β-cells

Cited by 24 publications

References 82 publications

Aurora Kinase A is critical for the Nkx6.1 mediated β-cell proliferation pathway

Aurora Kinase A is critical for the Nkx6.1 mediated β-cell proliferation pathway

ID3 regulates the MDC1-mediated DNA damage response in order to maintain genome stability

A Pdx-1-Regulated Soluble Factor Activates Rat and Human Islet Cell Proliferation

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