Frank DJ et al. (1996) West Coast Worm Meeting "CHARACTERIZATION AND CLONING OF ncl-1"

Frank DJ, Waring DA, Roth MB

[West Coast Worm Meeting, 1996]

The phenotype of homozyzous recessive ncl-1 mutant worms is the presence of enlarged nucleoli in all cells with the exception of the gut and gonad (Hedgecock & Herman, 1995). As this phenotype is easy to score and cell autonomous, ncl-1 has been used as a marker for mosaic analysis by a number of labs. We hypothesized that this phenotype might be due to an increase in ribosomal RNA sytnthesis. To test this we have performed in situ hybridizations on embryos using oligo probes specific for 5.8S rRNA and an internal transcribed spacer that is removed during rRNA processing. With both probes there is an increase in hybridization to the nascent rRNA transcripts in mutant relative to wildtype. Furthermore, by run-on transcription, there is at least a two-fold increase in both rRNA and 5S RNA transcription in ncl-1 vs wildtype. These data strongly suggest that the wildtype ncl-1 gene product is a negative regulator of RNA polymerase I and III transcription. We have rescued the ncl-1 phenotype first by injection of the cosmid C33C3 and, subsequently, cosmid ZK112 which has been sequenced by the genome project. Subcloning of ZK112 resulted in a 7.5 kb rescuing fragment that contains one predicted gene. To verify that this gene is ncl-1, we injected antisense RNA generated from a 1 kb fragment of this predicted gene into wildtype worms and have observed phenocopy in the F1 progeny. This gene is a zinc finger of the B box class and shares homology with proteins implicated in oncogenesis. We are currently generating antibodies against this protein to determine its expression pattern and subcellular localization. In addition, homozygous ncl-1 mutant cells are bigger than wildtype cells. Combined with the fact that ncl-1 appears to be a repressor of at least RNA polymerases I and III, we are considering the possibility that ncl-1 may play a critical role in growth control.

Frank DJ et al. (2002) Development "The Drosophila melanogaster gene brain tumor negatively regulates cell growth and ribosomal RNA synthesis."

Frank DJ, Edgar BA, Roth MB

[Development, 2002]

The regulation of ribosome synthesis is likely to play an important role in the regulation of cell growth. Previously, we have shown that the ncl-1 gene in Caenorhabditis elegans functions as an inhibitor of cell growth and ribosome synthesis. We now indicate that the Drosophila melanogaster tumor suppressor brain tumor (brat) is an inhibitor of cell growth and is a functional homolog of the C. elegans gene ncl-1. The brat gene is able to rescue the large nucleolus phenotype of ncl-1 mutants. We also show that brat mutant cells are larger, have larger nucleoli, and have more ribosomal RNA than wild-type cells. Furthermore, brat overexpressing cells contain less ribosomal RNA than control cells. These results suggest that the tumorous phenotype of brat mutants may be due to excess cell growth and ribosome synthesis.

Frank DJ et al. (1998) J Cell Biol "ncl-1 is required for the regulation of cell size and ribosomal RNA synthesis in Caenorhabditis elegans."

Frank DJ, Roth MB

[J Cell Biol, 1998]

Regulation of ribosome synthesis is an essential aspect of growth control. Thus far, little is known about the factors that control and coordinate these processes. We show here that the Caenorhabditis elegans gene ncl-1 encodes a zinc finger protein and may be a repressor of RNA polymerase I and III transcription and an inhibitor of cell growth. Loss of function mutations in ncl-1, previously shown to result in enlarged nucleoli, result in increased rates of rRNA and 5S RNA transcription and enlarged cells. Furthermore, ncl-1 adult worms are larger, have more protein, and have twice as much rRNA as wild-type worms. Localization studies show that the level of NCL-1 protein is independently regulated in different cells of the embryo. In wild-type embryos, cells with the largest nucleoli have the lowest level of NCL-1 protein. Based on these results we propose that ncl-1 is a repressor of ribosome synthesis and cell growth.

Clements CM et al. (2006) Proc Natl Acad Sci U S A "DJ-1, a cancer- and Parkinson's disease-associated protein, stabilizes the antioxidant transcriptional master regulator Nrf2."

McNally RS, Clements CM, Ting JP, Mak TW, Conti BJ

[Proc Natl Acad Sci U S A, 2006]

DJ-1/PARK7, a cancer- and Parkinson''s disease (PD)-associated protein, protects cells from toxic stresses. However, the functional basis of this protection has remained elusive. We found that loss of DJ-1 leads to deficits in NQO1 [NAD(P)H quinone oxidoreductase 1], a detoxification enzyme. This deficit is attributed to a loss of Nrf2 (nuclear factor erythroid 2-related factor), a master regulator of antioxidant transcriptional responses. DJ-1 stabilizes Nrf2 by preventing association with its inhibitor protein, Keap1, and Nrf2''s subsequent ubiquitination. Without intact DJ-1, Nrf2 protein is unstable, and transcriptional responses are thereby decreased both basally and after induction. This effect of DJ-1 on Nrf2 is present in both transformed lines and primary cells across human and mouse species. DJ-1''s effect on Nrf2 and subsequent effects on antioxidant responses may explain how DJ-1 affects the etiology of both cancer and PD, which are seemingly disparate disorders. Furthermore, this DJ-1/Nrf2 functional axis presents a therapeutic target in cancer treatment and justifies DJ-1 as a tumor biomarker.

Cornejo Castro EM et al. (2010) J Neural Transm "Parkinson's disease-associated DJ-1 modulates innate immunity signaling in Caenorhabditis elegans."

Autenrieth IB, Fiesel FC, Cornejo Castro EM, Schutz M, Oberhettinger P, Springer W, Kahle PJ, Waak J, Weber SS

[J Neural Transm, 2010]

DJ-1 is a neuroprotective gene mutated in recessive Parkinson's disease (PD). In addition to direct protective functions in neurons, DJ-1 regulates neuroinflammatory signaling in primary mouse brain astrocytes. To assess the influence of DJ-1 on innate immunity signaling in vivo, we have generated djr-1 knockout Caenorhabditis elegans. When grown on pathogenic gram-negative bacteria, djr-1 (-/-) worms showed stronger phosphorylation of p38 mitogen-activated protein kinase (PMK-1) and hyper-induction of PMK-1 target genes. Thus, PD-associated DJ-1 contributes to regulation of innate immunity.

Lee JY et al. (2012) Hum Mol Genet "Human DJ-1 and its homologs are novel glyoxalases."

Lee JY, Song J, Kwon K, Park C, Baek K, Jang S, Kim C, Kim J

[Hum Mol Genet, 2012]

Human DJ-1 is a genetic cause of early-onset Parkinson's disease (PD), although its biochemical function is unknown. We report here that human DJ-1 and its homologs of the mouse and Caenorhabditis elegans are novel types of glyoxalase, converting glyoxal or methylglyoxal to glycolic or lactic acid, respectively, in the absence of glutathione. Purified DJ-1 proteins exhibit typical Michaelis-Menten kinetics, which were abolished completely in the mutants of essential catalytic residues, consisting of cysteine and glutamic acid. The presence of DJ-1 protected mouse embryonic fibroblast and dopaminergically derived SH-SY5Y cells from treatments of glyoxals. Likewise, C. elegans lacking cDJR-1.1, a DJ-1 homolog expressed primarily in the intestine, protected worms from glyoxal-induced death. Sub-lethal doses of glyoxals caused significant degeneration of the dopaminergic neurons in C. elegans lacking cDJR-1.2, another DJ-1 homolog expressed primarily in the head region, including neurons. Our findings that DJ-1 serves as scavengers for reactive carbonyl species may provide a new insight into the causation of PD.

Johnson WM et al. (2016) Biochemistry "Regulation of DJ-1 by glutaredoxin 1 in vivo - implications for Parkinson's disease."

Mieyal JJ, Lin J, Currran PL, Wilson MA, Johnson WM, Ray A, Zhu X, Gorelenkova Miller O, Choe K, Yao C, Ravindranath V, Chen SG, Milkovic NM, Wang W, Golczak M, Wilson-Delfosse AL

[Biochemistry, 2016]

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, caused by the degeneration of the dopaminergic neurons in the substantia nigra. Mutations in PARK7 (DJ-1) result in early onset autosomal recessive PD, and oxidative modification of DJ-1 has been reported to regulate the protective activity of DJ-1 in vitro. Glutathionylation is a prevalent redox modification of proteins resulting from the disulfide adduction of the glutathione moiety to a reactive cysteine-SH; and glutathionylation of specific proteins has been implicated in regulation of cell viability. Glutaredoxin 1 (Grx1) is the principal deglutathionylating enzyme within cells, and it has been reported to mediate protection of dopaminergic neurons in C. elegans, however many of the functional downstream targets of Grx1 in vivo remain unknown. Previously, DJ-1 protein content was shown to decrease concomitantly with diminution of Grx1 protein content in cell culture of model neurons (SH-SY5Y and Neuro-2A lines). In the current study we aimed to investigate the regulation of DJ-1 by Grx1 in vivo and characterize its glutathionylation in vitro. Here, with Grx-/- mice we provide evidence that Grx1 regulates protein levels of DJ-1 in vivo. Furthermore, with model neuronal cells (SH-SY5Y) we observed decreased DJ-1 protein content in response to treatment with known glutathionylating agents; and with isolated DJ-1 we identified two distinct sites of glutathionylation. Finally, we found that overexpression of DJ-1 in the dopaminergic neurons partly compensates for the loss of the Grx1 homolog in a C. elegans in vivo model of PD. Therefore; our results reveal a novel redox modification of DJ-1 and suggest a novel regulatory mechanism for DJ-1 content in vivo.

Chen P et al. (2015) Metallomics "Age- and manganese-dependent modulation of dopaminergic phenotypes in a C. elegans DJ-1 genetic model of Parkinson's disease."

Bornhorst J, Bowman AB, Mukhopadhyay S, Chen P, DeWitt MR, Aschner M, Soares FA

[Metallomics, 2015]

Parkinson's disease (PD) is the second most common neurodegenerative disease, yet its etiology and pathogenesis are poorly understood. PD is characterized by selective dopaminergic (DAergic) degeneration and progressive hypokinetic motor impairment. Mutations in dj-1 cause autosomal recessive early-onset PD. DJ-1 is thought to protect DAergic neurons via an antioxidant mechanism, but the precise basis of this protection has not yet been resolved. Aging and manganese (Mn) exposure are significant non-genetic risk factors for PD. Caenorhabditis elegans (C. elegans) is an optimal model for PD and aging studies because of its simple nervous system, conserved DAergic machinery, and short 20-day lifespan. Here we tested the hypothesis that C. elegans DJ-1 homologues were protective against Mn-induced DAergic toxicity in an age-dependent manner. We showed that the deletion of C. elegans DJ-1 related (djr) genes, djr-1.2, decreased survival after Mn exposure. djr-1.2, the DJ-1 homologue was expressed in DAergic neurons and its deletion decreased lifespan and dopamine (DA)-dependent dauer movement behavior after Mn exposure. We also tested the role of DAF-16 as a regulator of dj-1.2 interaction with Mn toxicity. Lifespan defects resulting from djr-1.2 deletion could be restored to normal by overexpression of either DJR-1.2 or DAF-16. Furthermore, dauer movement alterations after djr-1.2 deletion were abolished by constitutive activation of DAF-16 through mutation of its inhibitor, DAF-2 insulin receptor. Taken together, our results reveal PD-relevant interactions between aging, the PD environmental risk factor manganese, and homologues of the established PD genetic risk factor DJ-1. Our data demonstrate a novel role for the DJ-1 homologue, djr-1.2, in mitigating Mn-dependent lifespan reduction and DA signaling alterations, involving DAF-2/DAF-16 signaling.

Sleeman BD et al. (2024) Math Biosci "A theoretical model of anaphase."

Stewart IW, Sleeman BD

[Math Biosci, 2024]

This paper develops a theory for anaphase in cells. After a brief description of microtubules, the mitotic spindle and the centrosome, a mathematical model for anaphase is introduced and developed in the context of the cell cytoplasm and liquid crystalline structures. Prophase, prometaphase and metaphase are then briefly described in order to focus on anaphase, which is the main study of this paper. The entities involved are modelled in terms of liquid crystal defects and microtubules are represented as defect flux lines. The mathematical techniques employed make extensive use of energy considerations based on the work that was developed by Dafermos (1970) from the classical Frank-Oseen nematic liquid crystal energy (Frank, 1958; Oseen, 1933). With regard to liquid crystal theory we introduce the concept of regions of influence for defects which it is believed have important implications beyond the subject of this paper. The results of this paper align with observed biochemical phenomena and are explored in application to HeLa cells and Caenorhabditis elegans. This unified approach offers the possibility of gaining insight into various consequences of mitotic abnormalities which may result in Down syndrome, Hodgkin lymphoma, breast, prostate and various other types of cancer.

Lee JY et al. (2013) Gene "DJR-1.2 of Caenorhabditis elegans is induced by DAF-16 in the dauer state."

Park C, Kim C, Lee JY, Kim J

[Gene, 2013]

Caenorhabditis elegans DJR-1.2, a homolog of human DJ-1, has recently been demonstrated to be a novel glyoxalase and protects worms against glyoxals. Here, we report that expression of DJR-1.2 is substantially increased during starvation as well as in the dauer stage. The induction of DJR-1.2 led to increased glyoxalase activity in the dauer state, thereby increasing protection against glyoxals. The induction is regulated by DAF-16, a transcriptional regulator implicated in oxidative stress and normal lifespan.