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The synergistic enhancement of AR-dependent transactivation by Dyrk1A and Arip4 expression is independent of the kinase activity of Dyrk1A. (A) Dyrk1A with Arip4 WT or Arip4 ⌬ 1165 – 1196 was expressed in CV-1 cells together with the MMTV-luciferase reporter gene. Cells were stimulated with the synthetic AR agonist R1881. Note that Arip4 ⌬ 1165 – 1196 , which lacks the Dyrk1A substrate consensus sequence, was also able to enhance the effect of Dyrk1A. WT, wild type. (B) Arip4 with Dyrk1A WT or Dyrk1A K188R was expressed in CV-1 cells together with the MMTV-luciferase reporter gene. Cells were stimulated with the synthetic AR agonist R1881. Note that kinase-de fi cient mutant Dyrk1A K188R was able to stimulate AR-mediated activation not different from that stimulated by Dyrk1A WT . Luciferase activities were normalized to protein content, and ratios were expressed relative to those obtained with AR in the presence of R1881 (value set at 1; second bar from left in panels A and B). Means and SEMs for three independent experiments are shown. For comparisons indicated by brackets, one asterisk indicates a P value of Ͻ 0.05 and three asterisks indicate a P value of Ͻ 0.0001.
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Dyrk1A, a mammalian homolog of the Drosophila minibrain gene, encodes a dual-specificity kinase, involved in neuronal development and in adult brain physiology. In humans, a third
copy of DYRK1A is present in Down syndrome (trisomy 21) and has been implicated in the etiology of mental retardation. To further understand
this pathology, we searched f...
Contexts in source publication
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... 16 h. The medium was changed to one without the antibiotic-antimycotic mixture, and the cells were transfected with the mouse mammary tumor virus (MMTV)-luciferase reporter gene plasmid pMTV-Luc and the appropriate plasmids for the expres- sion of Dyrk1A, Arip4, and either AR or GR by using 1 l of Lipofectamine 2000. For some experiments (see Fig. 6A), 480 ng of pMTV-Luc, 18 ng of pSTC-AR, 100 ng of pSVL-HA-Dyrk1A WT , and 40 ng of pCMV-FLAG- Arip4 WT or pCMV-FLAG-Arip4 1165-1196 were transfected per well. In all wells, the total amount of cytomegalovirus (CMV) promoter-containing vectors was 140 ng; when necessary, this amount was adjusted with pCMV-Tag2. For other experiments ...
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... Fig. 6A), 480 ng of pMTV-Luc, 18 ng of pSTC-AR, 100 ng of pSVL-HA-Dyrk1A WT , and 40 ng of pCMV-FLAG- Arip4 WT or pCMV-FLAG-Arip4 1165-1196 were transfected per well. In all wells, the total amount of cytomegalovirus (CMV) promoter-containing vectors was 140 ng; when necessary, this amount was adjusted with pCMV-Tag2. For other experiments (see Fig. 6B), 500 ng of pMTV-Luc, 15 ng of pSTC-AR, 50 ng of pCMV-FLAG-Arip4, and 100 ng of pSVL-HA-Dyrk1A WT or pSVL-HA- Dyrk1A K188R were transfected per well. The total amount of CMV promoter- containing vectors was adjusted to 150 ng per well with pCMV-Tag2. Experi- ments with GR (see Fig. 8) were performed with the same amounts as those used ...
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... of pSTC-AR, 50 ng of pCMV-FLAG-Arip4, and 100 ng of pSVL-HA-Dyrk1A WT or pSVL-HA- Dyrk1A K188R were transfected per well. The total amount of CMV promoter- containing vectors was adjusted to 150 ng per well with pCMV-Tag2. Experi- ments with GR (see Fig. 8) were performed with the same amounts as those used for the experiments just described (see Fig. 6B), but instead of pSTC-AR, pSTC-GR was used. In all experiments, the total amount of DNA per well was adjusted to 1 g with pBluescript II KS. For RNAi experiments, 50 ng of pSVL-HA-Dyrk1A (see Fig. 7A), pCMV-FLAG-Arip4 (see Fig. 7B), or pCMV- Tag2 (see Fig. 7C) was cotransfected with 15 ng of pSTC-AR, 500 ng of pMTV- Luc, and 410 ng of ...
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... we cotransfected CV-1 cells with an MMTV-luciferase reporter gene which is regulated by androgen and an expres- sion vector for AR. In addition, Dyrk1A, Arip4, both, or nei- ther was expressed. As shown in Fig. 6A, the activation of AR with the synthetic androgen R1881 led to a robust induction of the reporter gene (7.1-fold). This level of luciferase activity induced by hormone-activated AR without cofactors was set at 1. The expression of Dyrk1A led to a 4.3-fold (SEM, 0.35 [P 0.0001]) further increase in reporter gene activity, whereas ...
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... further increase in reporter gene activity, whereas transfection with a plasmid encoding wild-type Arip4 caused an increase of 1.2-fold (0.06 [P 0.05]). The expression of Dyrk1A and Arip4 together strongly augmented the inducing effect on the reporter gene and led to an increase of 18-fold (2.7 [P 0.0001]) over that obtained with activated AR (Fig. 6A). This enhancement was much stronger than the sum of the effects of Dyrk1A and Arip4 transfected alone. Therefore, these findings indicate a functional interaction of Dyrk1A and Arip4 which has a synergistic effect on AR-mediated transcrip- ...
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... contains a Dyrk1A substrate consensus sequence, it is reasonable to as- sume that Dyrk1A regulates the activity of Arip4 by phosphor- ylation. To test this hypothesis, we used a mutant of Arip4 (Arip4 ) which lacks the Dyrk1A substrate sequence and investigated the effect of the mutation on the activity of Arip4 in a transactivation assay with AR (Fig. 6A). Surpris- , which lacks the Dyrk1A substrate consensus sequence, was also able to enhance the effect of Dyrk1A. WT, wild type. (B) Arip4 with Dyrk1A WT or Dyrk1A K188R was expressed in CV-1 cells together with the MMTV-luciferase reporter gene. Cells were stimulated with the synthetic AR agonist R1881. Note that kinase-deficient mutant ...
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... 0.56]). These results led us to conclude that the activation of Arip4 by Dyrk1A is not mediated by the phosphorylation of serine 1168. To further substantiate whether the phosphorylation of Arip4 by Dyrk1A plays an essential role in an activation mechanism, we cotransfected Arip4 together with a kinase-deficient mutant of Dyrk1A (Dyrk1A K188R ) (Fig. 6B). In these experiments, Dyrk1A K188R was also able to activate AR-mediated transcription synergis- tically with Arip4, and the effect was not significantly different from that obtained with wild-type Dyrk1A (Arip4 plus wild- type Dyrk1A, 29.2-fold activation [3.2]; Arip4 plus Dyrk1A K188R , 22.2-fold activation [2.9] [P 0.12]). Appar- ...
Citations
... Of note, DYRK1A has been identified as an essential gene for SARS-CoV-2 infection in other CRISPR screens (12,14,15,18) and has recently been shown to be required for ACE2 expression (22). The interaction between DYRK1A and RAD54L2 has been reported previously (29). We used the co-immunoprecipitation (IP) assay to further validate the intermolecular interactions among TRAF3, DYRK1A, and RAD54L2. ...
... DYRK1A potentiates transcription via different mechanisms. It can interact with other transcription factors (RAD54L2 or FOXO1) to enhance the transcription of target genes (29,41). DYRK1A can also modulate the activity of p300/CBP or phosphorylates the C-terminal domain of RNAPII to activate transcription (42,43). ...
Angiotensin converting enzyme 2 (ACE2), the host receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is differentially expressed in a wide variety of tissues and cell types. The expression of ACE2 is under tight regulation, but the mechanisms regulating ACE2 expression have not yet been well defined. Through a genome-wide CRISPR knockout screen, we discovered that host factors TRAF3, DYRK1A, and RAD54L2 (TDR) form a complex to regulate the expression of ACE2. Knockout of TRAF3, DYRK1A, or RAD54L2 reduces the mRNA levels of ACE2 and inhibits the cellular entry of SARS-CoV-2. On the other hand, SARS-CoV-2 continuously evolves by genetic mutations for the adaption to the host. We have identified mutations in spike (S) (P1079T) and nucleocapsid (N) (S194L) that enhance the replication of SARS-CoV-2 in cells that express ACE2 at a low level. Our results have revealed the mechanisms for the transcriptional regulation of ACE2 and the adaption of SARS-CoV-2.
IMPORTANCE
The expression of ACE2 is essential for the entry of SARS-CoV-2 into host cells. We identify a new complex—the TDR complex—that acts to maintain the abundance of ACE2 in host cells. The identification and characterization of the TDR complex provide new targets for the development of therapeutics against SARS-CoV-2 infection. By analysis of SARS-CoV-2 virus replicating in cells expressing low levels of ACE2, we identified mutations in spike (P1079T) and nucleocapsid (S194L) that overcome the restriction of limited ACE2. Functional analysis of these key amino acids in S and N extends our knowledge of the impact of SARS-CoV-2 variants on virus infection and transmission.
... Our study revealed that DYRK1A KO can inhibit viral RNA synthesis by suppressing DMV formation independent of its catalytic activity, which has not yet been reported. DYRK1A primarily localizes in the nucleus, yet it acts as a potent host factor with wide-ranging transcriptional regulatory effects, capable of modulating proteins in both the nucleus and cytoplasm (54)(55)(56)(64)(65)(66)(67). Our RNA sequencing also demonstrated that DYRK1A influences a diverse array of host factors that are involved in multiple pathways (Table S1). ...
Coronaviruses (CoVs) pose a major threat to human and animal health worldwide, which complete viral replication by hijacking host factors. Identifying host factors essential for the viral life cycle can deepen our understanding of the mechanisms of virus–host interactions. Based on our previous genome-wide CRISPR screen of α-CoV transmissible gastroenteritis virus (TGEV), we identified the host factor dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A), but not DYRK1B, as a critical factor in TGEV replication. Rescue assays and kinase inhibitor experiments revealed that the effect of DYRK1A on viral replication is independent of its kinase activity. Nuclear localization signal modification experiments showed that nuclear DYRK1A facilitated virus replication. Furthermore, DYRK1A knockout significantly downregulated the expression of the TGEV receptor aminopeptidase N (ANPEP) and inhibited viral entry. Notably, we also demonstrated that DYRK1A is essential for the early stage of TGEV replication. Transmission electron microscopy results indicated that DYRK1A contributes to the formation of double-membrane vesicles in a kinase-independent manner. Finally, we validated that DYRK1A is also a proviral factor for mouse hepatitis virus, porcine deltacoronavirus, and porcine sapelovirus. In conclusion, our work demonstrated that DYRK1A is an essential host factor for the replication of multiple viruses, providing new insights into the mechanism of virus–host interactions and facilitating the development of new broad-spectrum antiviral drugs.
IMPORTANCE
Coronaviruses, like other positive-sense RNA viruses, can remodel the host membrane to form double-membrane vesicles (DMVs) as their replication organelles. Currently, host factors involved in DMV formation are not well defined. In this study, we used transmissible gastroenteritis virus (TGEV) as a virus model to investigate the regulatory mechanism of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) on coronavirus. Results showed that DYRK1A significantly inhibited TGEV replication in a kinase-independent manner. DYRK1A knockout (KO) can regulate the expression of receptor aminopeptidase N (ANPEP) and endocytic-related genes to inhibit virus entry. More importantly, our results revealed that DYRK1A KO notably inhibited the formation of DMV to regulate the virus replication. Further data proved that DYRK1A is also essential in the replication of mouse hepatitis virus, porcine deltacoronavirus, and porcine sapelovirus. Taken together, our findings demonstrated that DYRK1A is a conserved factor for positive-sense RNA viruses and provided new insights into its transcriptional regulation activity, revealing its potential as a candidate target for therapeutic design.
... Previously, we have identified protein-interactors of wild-type and kinase-dead DYRK1A (K188R) from HEK293 cells using affinity purification and mass spectrometry (17,31). In these purifications, we have observed significant enrichment of DCAF7, ARIP4, RB1, EP300, CREBBP, TRAF2, TRAF3, FAM53C, RNF169, many of which have been identified by many other groups as bona-fide DYRK1A interacting proteins (32)(33)(34)(35)(36). We also observed significant enrichment of TSC components TSC1 and TSC2 among proteins co-purified with wild-type as well as kinase-dead DYRK1A (K188R) (Figure 2A). ...
DYRK1A, which is linked to the dominant intellectual developmental disorder, microcephaly and Down syndrome in humans, regulates numerous cellular processes. Proteomics studeies revealed that DYRK1A interacts with the Tuberous sclerosis complex proteins, namely TSC1 and TSC2, which negatively regulate mTORC1 activation. Biochemical studies demonstrated that DYRK1A phosphorylates TSC2 at T1462, a modification that is known to inhibit Tuberous sclerosis complex activity and promote mTORC1 activity. Further, knockdown of DYRK1A reuslts in reduced cell growth and this phenotype is rescued by overexpression of RHEB, an activator of mTORC1. This results suggest that DYRK1A inhibits TSC complex activity and thereby promotes mTORC1 activity. Further, in Drosophila neuromuscular junction, growth defects caused by the loss of minibrain (mnb), the Drosophila homolog of DYRK1A, is rescued by the activation of TORC1 by RHEB overexpression. Overall, the results demonstrate an evolutionarly conserved role of DYRK1A/Mnb in the regulation of TORC1 pathway.
... We have recently reviewed bone studies in humans with DS and compared them to the sexual dimorphisms seen in mouse models of DS (LaCombe and Roper, 2020; Thomas et al., 2020). DYRK1A has been shown to activate androgen receptor-mediated transcription, which could change steroid hormone-controlled cellular activity (Sitz et al., 2004). Despite evidence of sex differences in DS phenotypes, most published preclinical therapeutic studies using DS mouse models either failed to include sex as a factor or were underpowered to detect interactive effects of sex and genotype (Block et al., 2015;Gardiner, 2015). ...
The neurotypical spatiotemporal patterns of gene expression are disrupted in Down syndrome (DS) by trisomy of human chromosome 21 (Hsa21), resulting in altered behavioral development and brain circuitry. The Ts65Dn DS mouse model exhibits similar phenotypes to individuals with DS due to three copies of approximately one-half of the genes found on Hsa21. Dual-specificity Tyrosine Phosphorylation-regulated Kinase 1a (Dyrk1a), one of these triplicated genes, is an attractive target to normalize brain development due to its influence in cellular brain deficits seen in DS. We hypothesized that postnatal development of DYRK1A expression is dysregulated in trisomic animals, and found significant overexpression of DYRK1A in the hippocampus, cerebral cortex, and cerebellum at postnatal day (P) 15 in male—but not female—Ts65Dn mice. We then hypothesized the existence of sex-dependent effects of trisomy on neurobehavioral attributes during P16–17, and that administration of a DYRK1A inhibitor (CX-4945, ~75 mg/kg) beginning on P14 would normalize aberrant behavior in trisomic animals. Both male and female trisomic mice given control injections of phosphate buffered saline (PBS) displayed sustained levels of locomotor activity over a 10-minute test in contrast to the PBS-treated euploid animals that showed significant within-session habituation. Trisomic animals were more persistent in choosing to remain in home shavings in a preference test. Treatment with CX-4945 failed to confirm therapeutic effects. CX-4945 prevented growth, and both CX-4945 and its 10% dimethyl sulfoxide vehicle affected locomotor activity in trisomic and euploid groups, indicating a non-specific disruption of behavior. Despite the negative outcomes for CX-4945, the novel demonstration of sexually dimorphic DYRK1A expression in trisomic animals at P15 supports the broader hypothesis that overexpression of trisomic genes in DS can vary with age, sex, and brain region. Identifying the developmental timing of periods of dysregulated DYRK1A may be important for understanding individual differences in neurodevelopmental trajectories in DS and for developing effective therapeutic interventions targeting DYRK1A.
... Interestingly, analysis of de novo DYRK1A mutations found in MRD7 patients pointed at mutations outside of the kinase domain with no impact on the kinase activity, suggesting kinase-activity independent functions for DYRK1A [60]. In addition to this, a synergic Dyrk1a and Arip4 activating effect on androgen receptor-and glucocorticoid receptor-mediated transcriptional activation was observed independently of Dyrk1a kinase activity [61]. Hence, like other kinases, DYRK1A seems to have phosphorylation-independent functions such as scaffolding, allosteric regulation or protein-DNA interaction [62]. ...
... DYRK1A was found to bind to the SWI/SNF chromatin remodeling complex known to interact with the neuron-restrictive silencer factor (REST/NRSF) and its overexpression led to perturbation of the expression of a cluster of gene located near the REST/NRSF binding sites and essential for neuronal differentiation [119]. DYRK1A interacts with the SNF2-like chromatin remodeling ATPase ARIP4 and synergistically activates androgen receptor-mediated and glucocorticoid receptor-mediated transcription [61]. DYRK1A also phosphorylates histone H3, antagonizing chromatin binding of the heterochromatin protein HP1 and leading to the transcriptional activation of genes involved in stress response including cytokines [120]. ...
Down syndrome is the main cause of intellectual disabilities with a large set of comorbidities from developmental origins but also that appeared across life span. Investigation of the genetic overdosage found in Down syndrome, due to the trisomy of human chromosome 21, has pointed to one main driver gene, the Dual-specificity tyrosine-regulated kinase 1A (Dyrk1a). Dyrk1a is a murine homolog of the drosophila minibrain gene. It has been found to be involved in many biological processes during development and in adulthood. Further analysis showed its haploinsufficiency in mental retardation disease 7 and its involvement in Alzheimer’s disease. DYRK1A plays a role in major developmental steps of brain development, controlling the proliferation of neural progenitors, the migration of neurons, their dendritogenesis and the function of the synapse. Several strategies targeting the overdosage of DYRK1A in DS with specific kinase inhibitors have showed promising evidence that DS cognitive conditions can be alleviated. Nevertheless, providing conditions for proper temporal treatment and to tackle the neurodevelopmental and the neurodegenerative aspects of DS across life span is still an open question.
... From these cells, we affinity-purified Flag-DYRK1A from cytoplasmic fractions (S100) and analyzed the eluates by SDS-PAGE and silver staining (Fig. 1A). To identify the interacting proteins, we performed MudPIT analysis and observed enrichment of a number of proteins including previously known interactors including DCAF7, ARIP4 (Fig. 1B) [34][35][36]. Among the novel interactions of DYRK1A, we found TRAF2, an E3 ubiquitin ligase for both K48-and K63linked ubiquitination. ...
Dual specificity tyrosine phosphorylation regulated kinase 1A, DYRK1A, functions in multiple cellular pathways, including signaling, endocytosis, synaptic transmission, and transcription. Alterations in dosage of DYRK1A leads to defects in neurogenesis, cell growth, and differentiation, and may increase the risk of certain cancers. DYRK1A localizes to a number of subcellular structures including vesicles where it is known to phosphorylate a number of proteins and regulate vesicle biology. However, the mechanism by which it translocates to vesicles is poorly understood. Here we report the discovery of TRAF2, an E3 ligase, as an interaction partner of DYRK1A. Our data suggest that TRAF2 binds to PVQE motif residing in between the PEST and histidine repeat domain (HRD) of DYRK1A protein, and mediates K63-linked ubiquitination of DYRK1A. This results in translocation of DYRK1A to the vesicle membrane. DYRK1A increases phosphorylation of Sprouty 2 on vesicles, leading to the inhibition of EGFR degradation, and depletion of TRAF2 expression accelerates EGFR degradation. Further, silencing of DYRK1A inhibits the growth of glioma cells mediated by TRAF2. Collectively, these findings suggest that the axis of TRAF2–DYRK1A-Sprouty 2 can be a target for new therapeutic development for EGFR-mediated human pathologies.
... B-ALL cells are sensitive to DYRK1A pharmacologic inhibition. Studies have indicated that DYRK1A can perform several functions independent of its kinase activity, such as regulation of chromatin remodeling (25). To determine whether pre-B cell and B-ALL dependence on DYRK1A requires its kinase activity, we mutated the lysine 188 residue of its ATP-binding domain to arginine (K188R), thereby rendering it catalytically inactive. ...
DYRK1A is a serine/threonine kinase encoded on human chromosome 21 (HSA21) that has been implicated in several pathologies of Down syndrome (DS), including cognitive deficits and Alzheimer's disease. Although children with DS are predisposed to developing leukemia, especially B cell acute lymphoblastic leukemia (B-ALL), the HSA21 genes that contribute to malignancies remain largely undefined. Here, we report that DYRK1A is overexpressed and required for B-ALL. Genetic and pharmacologic inhibition of DYRK1A decreased leukemic cell expansion and suppressed B-ALL development in vitro and in vivo. Furthermore, we found that FOXO1 and STAT3, transcription factors that are indispensable for B cell development, are critical substrates of DYRK1A. Loss of DYRK1A-mediated FOXO1 and STAT3 signaling disrupted DNA damage and ROS regulation, respectively, leading to preferential cell death in leukemic B cells. Thus, we reveal a DYRK1A/FOXO1/STAT3 axis that facilitates the development and maintenance of B-ALL.
... Early work identified HIPK3 as an activator of androgen receptor function (Moilanen et al., 1998) and a genome-wide RNA interference screen identified HIPK2 as a new regulator of androgen receptorinduced gene expression (Imberg-Kazdan et al., 2013). Also the HIPK-related kinase DYRK1a was found to associate with the androgen receptor-interacting protein 4 (Arip4) to trigger androgen receptor-and glucocorticoid receptor-dependent transcription (Sitz et al., 2004). The coactivator function of HIPK2 for estrogen receptor-mediated gene expression discovered here might also be of pathophysiological relevance, as revealed by the analysis of gene dependency screens for 712 cancer cell lines spanning 3 large-scale RNAi datasets (McFarland et al., 2018). ...
The protein kinase homeodomain-interacting protein kinase 2 (HIPK2) plays an important role in development and in the response to external cues. The kinase associates with an exceptionally large number of different transcription factors and chromatin regulatory proteins to direct distinct gene expression programs. In order to investigate the function of HIPK2 for chromatin compaction, HIPK2 was fused to the DNA-binding domains of Gal4 or LacI, thus allowing its specific targeting to binding sites for these transcription factors that were integrated in specific chromosome loci. Tethering of HIPK2 resulted in strong decompaction of euchromatic and heterochromatic areas. HIPK2-mediated heterochromatin decondensation started already 4 h after its chromatin association and required the functionality of its SUMO-interacting motif. This process was paralleled by disappearance of the repressive H3K27me3 chromatin mark, recruitment of the acetyltransferases CBP and p300 and increased histone acetylation at H3K18 and H4K5. HIPK2-mediated chromatin decompaction was strongly inhibited in the presence of a CBP/p300 inhibitor and completely blocked by the BET inhibitor JQ1, consistent with a causative role of acetylations for this process. Chromatin tethering of HIPK2 had only a minor effect on basal transcription, while it strongly boosted estrogen-triggered gene expression by acting as a transcriptional cofactor.
... The functional analysis also revealed the presence of three inserts in the kinase core of the protein that are essential for kinase function. These may assist binding to partner proteins (Kelly and Rahmani, 2005;Sitz et al., 2004), similar to human DYRK2, that also acts as an adaptor for the formation of the E3 ubiquitin ligase EDPV (Maddika and Chen, 2009). Indeed, the deletion of Insert II, which is cytocidal when cells are exposed to 8-pCPT-cAMP treatment might be caused by effects on the capacity for binding partner interaction. ...
The sleeping sickness parasite, Trypanosoma brucei, uses quorum sensing (QS) to balance proliferation and transmission potential in the mammal bloodstream. A signal transduction cascade regulates this process, a component of which is a divergent member of the DYRK family of protein kinases, TbDYRK. Phylogenetic and mutational analysis in combination with activity and phenotypic assays revealed that TbDYRK exhibits a pre-activated conformation and an atypical HxY activation loop motif, unlike DYRK kinases in other eukaryotes. Phosphoproteomic comparison of TbDYRK null mutants with wild-type parasites identified molecules that operate on both the inhibitory ‘slender retainer’ and activatory ‘stumpy inducer’ arms of the QS control pathway. One of these molecules, the RNA-regulator TbZC3H20, regulates parasite QS, this being dependent on the integrity of its TbDYRK phosphorylation site. This analysis reveals fundamental differences to conventional DYRK family regulation and links trypanosome environmental sensing, signal transduction and developmental gene expression in a coherent pathway.
... The functional analysis also revealed the presence of three inserts in the kinase core of the protein that are essential for kinase function. These may assist binding to partner proteins (Kelly and Rahmani, 2005;Sitz et al., 2004), similar to human DYRK2, that also acts as an adaptor for the formation of the E3 ubiquitin ligase EDPV (Maddika and Chen, 2009). Indeed, the deletion of Insert II, which is cytocidal when cells are exposed to 8-pCPT-cAMP treatment might be caused by effects on the capacity for binding partner interaction. ...
The sleeping sickness parasite, Trypanosoma brucei, uses quorum sensing (QS) to balance proliferation and transmission potential in the mammal bloodstream. A signal transduction cascade regulates this process, a component of which is a divergent member of the DYRK family of protein kinases, TbDYRK. Phylogenetic and mutational analysis in combination with activity and phenotypic assays revealed that TbDYRK exhibits a pre-activated conformation and an atypical HxY activation loop motif, unlike DYRK kinases in other eukaryotes. Phosphoproteomic comparison of TbDYRK null mutants with wild-type parasites identified molecules that operate on both the inhibitory ‘slender retainer’ and activatory ‘stumpy inducer’ arms of the QS control pathway. One of these molecules, the RNA-regulator TbZC3H20, regulates parasite QS, this being dependent on the integrity of its TbDYRK phosphorylation site. This analysis reveals fundamental differences to conventional DYRK family regulation and links trypanosome environmental sensing, signal transduction and developmental gene expression in a coherent pathway.
