Identification of Molecular Profile of Ear Fibroblasts Derived from Spindle-Transferred Holstein Cattle with Ooplasts from Taiwan Yellow Cattle under Heat Stress.

Global warming has a significant impact on the dairy farming industry, as heat stress causes reproductive endocrine imbalances and leads to substantial economic losses, particularly in tropical-subtropical regions. The Holstein breed, which is widely used for dairy production, is highly susceptible to heat stress, resulting in a dramatic reduction in milk production during hot seasons. However, previous studies have shown that cells of cows produced from reconstructed embryos containing cytoplasm (o) from Taiwan yellow cattle (Y) have improved thermotolerance despite their nuclei (n) being derived from heat-sensitive Holstein cattle (H). Using spindle transfer (ST) technology, we successfully produced ST-Yo-Hn cattle and proved that the thermotolerance of their ear fibroblasts is similar to that of Y and significantly better than that of H (p < 0.05). Despite these findings, the genes and molecules responsible for the different sensitivities of cells derived from ST-Yo-Hn and H cattle have not been extensively investigated. In the present study, ear fibroblasts from ST-Yo-Hn and H cattle were isolated, and differentially expressed protein and gene profiles were compared with or without heat stress (hs) (42 °C for 12 h). The results revealed that the relative protein expression levels of pro-apoptotic factors, including Caspase-3, -8, and -9, in the ear fibroblasts from the ST-Yo-Hn-hs group were significantly lower (p < 0.05) than those from the H-hs group. Conversely, the relative expression levels of anti-apoptotic factors, including GNA14 protein and the CRELD2 and PRKCQ genes, were significantly higher (p < 0.05) in the ear fibroblasts from the ST-Yo-Hn-hs group compared to those from the H-hs group. Analysis of oxidative phosphorylation-related factors revealed that the relative expression levels of the GPX1 gene and Complex-I, Complex-IV, CAT, and PGLS proteins were significantly higher (p < 0.05) in the ear fibroblasts from the ST-Yo-Hn-hs group compared to those from the H-hs group. Taken together, these findings suggest that ear fibroblasts from ST-Yo-Hn cattle have superior thermotolerance compared to those from H cattle due to their lower expression of pro-apoptotic factors and higher expression of oxidative phosphorylation and antioxidant factors. Moreover, this improved thermotolerance is attributed, at least partially, to the cytoplasm derived from more heat-tolerant Y cattle. Hence, using ST technology to produce more heat-tolerant H cattle containing Y cytoplasm could be a feasible approach to alleviate the negative impacts of heat stress on dairy cattle in tropical-subtropical regions.

Comparative analyses of the Smith-Magenis syndrome protein RAI1 in mice and common marmoset monkeys.

Retinoic acid-induced 1 (RAI1) encodes a transcriptional regulator critical for brain development and function. RAI1 haploinsufficiency in humans causes a syndromic autism spectrum disorder known as Smith-Magenis syndrome (SMS). The neuroanatomical distribution of RAI1 has not been quantitatively analyzed during the development of the prefrontal cortex, a brain region critical for cognitive function and social behaviors and commonly implicated in autism spectrum disorders, including SMS. Here, we performed comparative analyses to uncover the evolutionarily convergent and divergent expression profiles of RAI1 in major cell types during prefrontal cortex maturation in common marmoset monkeys (Callithrix jacchus) and mice (Mus musculus). We found that while RAI1 in both species is enriched in neurons, the percentage of excitatory neurons that express RAI1 is higher in newborn mice than in newborn marmosets. By contrast, RAI1 shows similar neural distribution in adult marmosets and adult mice. In marmosets, RAI1 is expressed in several primate-specific cell types, including intralaminar astrocytes and MEIS2-expressing prefrontal GABAergic neurons. At the molecular level, we discovered that RAI1 forms a protein complex with transcription factor 20 (TCF20), PHD finger protein 14 (PHF14), and high mobility group 20A (HMG20A) in the marmoset brain. In vitro assays in human cells revealed that TCF20 regulates RAI1 protein abundance. This work demonstrates that RAI1 expression and protein interactions are largely conserved but with some unique expression in primate-specific cells. The results also suggest that altered RAI1 abundance could contribute to disease features in disorders caused by TCF20 dosage imbalance.

Smith-Magenis syndrome protein RAI1 regulates body weight homeostasis through hypothalamic BDNF-producing neurons and neurotrophin downstream signalling.

Retinoic acid-induced 1 (RAI1) haploinsufficiency causes Smith-Magenis syndrome (SMS), a genetic disorder with symptoms including hyperphagia, hyperlipidemia, severe obesity, and autism phenotypes. RAI1 is a transcriptional regulator with a pan-neural expression pattern and hundreds of downstream targets. The mechanisms linking neural Rai1 to body weight regulation remain unclear. Here we find that hypothalamic brain-derived neurotrophic factor (BDNF) and its downstream signalling are disrupted in SMS (Rai1+/-) mice. Selective Rai1 loss from all BDNF-producing cells or from BDNF-producing neurons in the paraventricular nucleus of the hypothalamus (PVH) induced obesity in mice. Electrophysiological recordings revealed that Rai1 ablation decreased the intrinsic excitability of PVHBDNF neurons. Chronic treatment of SMS mice with LM22A-4 engages neurotrophin downstream signalling and delayed obesity onset. This treatment also partially rescued disrupted lipid profiles, insulin intolerance, and stereotypical repetitive behaviour in SMS mice. These data argue that RAI1 regulates body weight and metabolic function through hypothalamic BDNF-producing neurons and that targeting neurotrophin downstream signalling might improve associated SMS phenotypes.

rAAV-CRISPRa therapy corrects Rai1 haploinsufficiency and rescues selective disease features in Smith-Magenis syndrome mice.

Haploinsufficiency in retinoic acid induced 1 (RAI1) causes Smith-Magenis syndrome (SMS), a severe neurodevelopmental disorder characterized by neurocognitive deficits and obesity. Currently, curative treatments for SMS do not exist. Here, we take a recombinant adeno-associated virus (rAAV)-clustered regularly interspaced short palindromic repeats activation (CRISPRa) approach to increase expression of the remaining intact Rai1 allele. Building upon our previous work that found the paraventricular nucleus of hypothalamus plays a central role in SMS pathogenesis, we performed paraventricular nucleus of hypothalamus-specific rAAV-CRISPRa therapy by increasing endogenous Rai1 expression in SMS (Rai1±) mice. We found that rAAV-CRISPRa therapy rescues excessive repetitive behavior, delays the onset of obesity, and partially reduces hyperphagia in SMS mice. Our work provides evidence that rAAV-CRISPRa therapy during early adolescence can boost the expression of healthy Rai1 allele and modify disease progression in a mouse model of Smith-Magenis syndrome.

Loss of Rai1 enhances hippocampal excitability and epileptogenesis in mouse models of Smith-Magenis syndrome.

Hyperexcitability of brain circuits is a common feature of autism spectrum disorders (ASDs). Genetic deletion of a chromatin-binding protein, retinoic acid induced 1 (RAI1), causes Smith-Magenis syndrome (SMS). SMS is a syndromic ASD associated with intellectual disability, autistic features, maladaptive behaviors, overt seizures, and abnormal electroencephalogram (EEG) patterns. The molecular and neural mechanisms underlying abnormal brain activity in SMS remain unclear. Here we show that panneural Rai1 deletions in mice result in increased seizure susceptibility and prolonged hippocampal seizure duration in vivo and increased dentate gyrus population spikes ex vivo. Brain-wide mapping of neuronal activity pinpointed selective cell types within the limbic system, including the hippocampal dentate gyrus granule cells (dGCs) that are hyperactivated by chemoconvulsant administration or sensory experience in Rai1-deficient brains. Deletion of Rai1 from glutamatergic neurons, but not from gamma-aminobutyric acidergic (GABAergic) neurons, was responsible for increased seizure susceptibility. Deleting Rai1 from the Emx1Cre-lineage glutamatergic neurons resulted in abnormal dGC properties, including increased excitatory synaptic transmission and increased intrinsic excitability. Our work uncovers the mechanism of neuronal hyperexcitability in SMS by identifying Rai1 as a negative regulator of dGC intrinsic and synaptic excitability.

Effects of Helicopter Parenting on Tutoring Engagement and Continued Attendance at Cram Schools.

Attending cram school has long been a trend in ethnic Chinese culture areas, including Taiwan. Despite the fact that school reform policies have been implemented in Taiwan, cram schools have continued to prosper. Therefore, in this educational culture, how to achieve a good educational effect is also a topic worthy of discussion. However, whether students really engage in those tutoring programs provided by cram schools has seldom been studied. To address this gap, this study explored how parents' hovering attitude toward life and coursework influences their children's engagement in cram schools. This study targeted those students who attend English cram schools to test the correlates between two types of helicopter parenting, tutoring engagement and continued attendance at cram schools. A total of 320 questionnaires were sent out, and 300 were returned, giving an overall response rate of 93.75%. Excluding seven incomplete or invalid questionnaires, 293 valid questionnaires were received. The results of this study show that hovering behavior awareness is negatively related to cram school engagement, whereas cram school engagement is positively related to the intention to continue attending cram school. Moreover, the results imply that parents should alleviate their helicoptering behavior to enhance their children's engagement in cram school tutoring programs.

Effects of intracytoplasmic sperm injection timing and fertilization methods on the development of bovine spindle transferred embryos.

Cytoplasmic replacement by spindle transfer (ST) technique can be applied to improve the developmental competence of poor qualitied or aged oocytes. In cattle, ST technology has not been well established for producing embryos and the calves successfully using intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF). The objective of this study was to develop a novel procedure for producing bovine ST embryos, which could be fundamental to applying ST technology in other mammals. In the present study, the efficacies of performing ICSI before (ICSI-ST) or after (ST-ICSI) and IVF on the development of ST bovine embryos were investigated. Results indicated that the blastocyst rate of ST embryos produced by ICSI-ST (24.7%) was higher (P < 0.05) than that produced by ST-ICSI (5.9%). On the other hand, ST-IVF had the highest fertilization rate (97.3%), polyspermy rate (24.7%), and lowest blastocyst rate (22.7%) when compared to denuded oocytes (DO), zona cut oocytes (ZC), and cumulus-oocyte complexes (COCs)-IVF groups. Finally, the in vitro development rates of ICSI-ST (24.5%) and ST-IVF (25.2%) were not significantly different (P > 0.05). However, the pregnancy rate (46.7%) and birth rate (33.3%) of ST-IVF were higher (P < 0.05) than those of ICSI-ST (6.3% and 0%, respectively). The percentage of mitochondrial DNA (mtDNA) heteroplasmy derived from donor karyoplasts of the 5 claves was between 2% and 18%. Taken together, performing ICSI prior to ST can improve the embryonic development of ST bovine embryos. Moreover, using IVF, instead of ICSI, for ST oocyte fertilization dramatically increased the pregnancy rate and birth rate of ST calves, in which mtDNA heteroplasmy derived from donor karyoplasts exists.

Temporal dissection of Rai1 function reveals brain-derived neurotrophic factor as a potential therapeutic target for Smith-Magenis syndrome.

Haploinsufficiency of retinoic acid-induced 1 (RAI1) is responsible for Smith-Magenis syndrome (SMS), a childhood neurodevelopmental disorder associated with hyperphagia, obesity and autistic features. We previously showed that constitutive inactivation of one or both copies of Rai1 in the germline or developing brain induces SMS-like neurobehavioral deficits and obesity in mice. By contrast, the postnatal function of Rai1 is unclear. Here, we globally deleted one or both copies of Rai1 during two postnatal developmental windows by generating an inducible Rai1 knockout mouse model. We found that delayed Rai1 deletion at 3 or 8 weeks of age had no effect on neurobehavioral functions but resulted in adult-onset obesity and decreased expression of brain-derived neurotrophic factor (Bdnf) in the hypothalamus. Remarkably, genetic overexpression of human Bdnf in Rai1 heterozygous mice reversed SMS-like obesity, hyperphagia, metabolic syndrome-like features and hyposociability. Increasing Bdnf signaling in the paraventricular nucleus of the hypothalamus or the ventromedial nucleus of the hypothalamus was sufficient to mediate the anti-obesity effect. Our work identifies the function of Rai1 in different temporal windows after birth and provides in vivo evidence that increasing Bdnf signaling is therapeutically effective in a preclinical mouse model of SMS.

Dosage-sensitive genes in autism spectrum disorders: From neurobiology to therapy.

Autism spectrum disorders (ASDs) are a group of heterogenous neurodevelopmental disorders affecting 1 in 59 children. Syndromic ASDs are commonly associated with chromosomal rearrangements or dosage imbalance involving a single gene. Many of these genes are dosage-sensitive and regulate transcription, protein homeostasis, and synaptic function in the brain. Despite vastly different molecular perturbations, syndromic ASDs share core symptoms including social dysfunction and repetitive behavior. However, each ASD subtype has a unique pathogenic mechanism and combination of comorbidities that require individual attention. We have learned a great deal about how these dosage-sensitive genes control brain development and behaviors from genetically-engineered mice. Here we describe the clinical features of eight monogenic neurodevelopmental disorders caused by dosage imbalance of four genes, as well as recent advances in using genetic mouse models to understand their pathogenic mechanisms and develop intervention strategies. We propose that applying newly developed quantitative molecular and neuroscience technologies will advance our understanding of the unique neurobiology of each disorder and enable the development of personalized therapy.

E2F1 sumoylation as a protective cellular mechanism in oxidative stress response.

Oxidative stress is a ubiquitous threat to all aerobic organisms and has been implicated in numerous pathological conditions such as cancer. Here we demonstrate a pivotal role for E2F1, a cell cycle regulatory transcription factor, in cell tolerance of oxidative stress. Cells lacking E2F1 are hypersensitive to oxidative stress due to the defects in cell cycle arrest. Oxidative stress inhibits E2F1 transcriptional activity, independent of changes in association with Rb and without decreasing its DNA-binding activity. Upon oxidative insult, SUMO2 is extensively conjugated to E2F1 mainly at lysine 266 residue, which specifically modulates E2F1 transcriptional activity to enhance cell cycle arrest for cell survival. We identify SENP3, a desumoylating enzyme, as an E2F1-interacting partner. Oxidative stress inhibits the interaction between E2F1 and SENP3, which leads to accumulation of sumoylated E2F1. SENP3-deficient cells exhibit hypersumoylation of E2F1 and are resistant to oxidative insult. High levels of SENP3 in breast cancer are associated with elevated levels of E2F targets, high tumor grade, and poor survival. Given the prevalence of elevated levels of SENP3 across numerous cancer types, the SENP3-E2F1 axis may serve as an avenue for therapeutic intervention in cancer.

Development of the Nurses' Occupational Stressor Scale.

Although nurses work in stressful environments, stressors in such environments have yet to be clearly assessed. This study aimed to develop a Nurses' Occupational Stressor Scale (NOSS) with high reliability and validity. Candidate questions for the NOSS were generated by expert consensus following focus group feedback, and were used to survey in 2013. A shorter version was then developed after examination for validity and reproducibility in 2014. The accuracy of the short version of the NOSS for predicting nurses' stress levels was evaluated based on receiver operating characteristic curves to compare existing instruments for measuring stress outcomes, namely personal burnout, client-related burnout, job dissatisfaction, and intention to leave. Examination for validity and reproducibility yielded a shorter version of NOSS with only 21 items was considered sufficient for measuring stressors in nurses' work environments. Nine subscales were included: (1) work demands, (2) work-family conflict, (3) insufficient support from coworkers or caregivers, (4) workplace violence and bullying, (5) organizational issues, (6) occupational hazards, (7) difficulty taking leave, (8) powerlessness, and (9) unmet basic physiological needs. The 21-item NOSS proved to have high concurrent and construct validity. The correlation coefficients of the subscales for test-retest reliability ranged from 0.71 to 0.83. The internal consistency (Cronbach's α) coefficients ranged from 0.35 to 0.77. The NOSS exhibited accurate prediction of personal burnout, client-related burnout, job dissatisfaction, and intention to leave.

Cell Cycle-Dependent Switch of TopBP1 Functions by Cdk2 and Akt.

Cdk2-dependent TopBP1-treslin interaction is critical for DNA replication initiation. However, it remains unclear how this association is terminated after replication initiation is finished. Here, we demonstrate that phosphorylation of TopBP1 by Akt coincides with cyclin A activation during S and G2 phases and switches the TopBP1-interacting partner from treslin to E2F1, which results in the termination of replication initiation. Premature activation of Akt in G1 phase causes an early switch and inhibits DNA replication. TopBP1 is often overexpressed in cancer and can bypass control by Cdk2 to interact with treslin, leading to enhanced DNA replication. Consistent with this notion, reducing the levels of TopBP1 in cancer cells restores sensitivity to a Cdk2 inhibitor. Together, our study links Cdk2 and Akt pathways to the control of DNA replication through the regulation of TopBP1-treslin interaction. These data also suggest an important role for TopBP1 in driving abnormal DNA replication in cancer.

CGRRF1, a growth suppressor, regulates EGFR ubiquitination in breast cancer.

BACKGROUND: CGRRF1 is a growth suppressor and consists of a transmembrane domain and a RING-finger domain. It functions as a RING domain E3 ubiquitin ligase involved in endoplasmic reticulum-associated degradation. The expression of CGRRF1 is decreased in cancer tissues; however, the role of CGRRF1 in breast cancer and the mechanism(s) of its growth suppressor function remain to be elucidated. METHODS: To investigate whether CGRRF1 inhibits the growth of breast cancer, we performed MTT assays and a xenograft experiment. Tumors harvested from mice were further analyzed by reverse phase protein array (RPPA) analysis to identify potential substrate(s) of CGRRF1. Co-immunoprecipitation assay was used to verify the interaction between CGRRF1 and its substrate, followed by in vivo ubiquitination assays. Western blot, subcellular fractionation, and reverse transcription quantitative polymerase chain reaction (qRT-PCR) were performed to understand the mechanism of CGRRF1 action in breast cancer. Publicly available breast cancer datasets were analyzed to examine the association between CGRRF1 and breast cancer. RESULTS: We show that CGRRF1 inhibits the growth of breast cancer in vitro and in vivo, and the RING-finger domain is important for its growth-inhibitory activity. To elucidate the mechanism of CGRRF1, we identified EGFR as a new substrate of CGRRF1. CGRRF1 ubiquitinates EGFR through K48-linked ubiquitination, which leads to proteasome degradation. In addition to regulating the stability of EGFR, knockout of CGRRF1 enhances AKT phosphorylation after EGF stimulation. By analyzing the breast cancer database, we found that patients with low CGRRF1 expression have shorter survival. As compared to normal breast tissues, the mRNA levels of CGRRF1 are lower in breast carcinomas, especially in HER2-positive and basal-like breast cancers. We further noticed that CGRRF1 promoter methylation is increased in breast cancer as compared to that in normal breast tissue, suggesting that CGRRF1 is epigenetically modified in breast cancer. Treatment of 5-azactidine and panobinostat restored CGRRF1 expression, supporting that the promoter of CGRRF1 is epigenetically modified in breast cancer. Since 5-azactidine and panobinostat can increase CGRRF1 expression, they might be potential therapies for breast cancer treatment. CONCLUSION: We demonstrated a tumor-suppressive function of CGRRF1 in breast cancer and identified EGFR as its target.

Cognitive and motor dual task gait training exerted specific training effects on dual task gait performance in individuals with Parkinson's disease: A randomized controlled pilot study.

Gait impairments in Parkinson's disease (PD) are aggravated under dual task conditions. Providing effective training to enhance different dual task gait performance is important for PD rehabilitation. This pilot study aimed to investigate the effects of cognitive and motor dual task gait training on dual task gait performance in PD. Eighteen PD participants (n = 6 per training group) were assigned to cognitive dual task gait training (CDTT), motor dual task gait training (MDTT), or general gait training (control) group randomly. The training was 30 min each session, 3 sessions per week for 4 weeks. Primary outcomes including gait performance during cognitive dual task, motor dual task, and single walking were assessed at pre- and post-training. The results showed decreased double support time during cognitive dual task walking after CDTT (-17.1±10.3%) was significantly more than MDTT (6.3±25.6%, p = .006) and control training (-5.6±7.8%, p = .041). Stride time variability during motor dual task walking decreased more after MDTT (-16.3±32.3%) than CDTT (38.6±24.0%, p = .015) and control training (36.8±36.4%, p = .041). CDTT also improved motor dual task walking performance especially on gait speed (13.8±10.71%, p = .046) stride length (10.5±6.6%, p = .046), and double support time (-8.0±2.0%, p = .028). CDTT improved single walking performance as well on gait speed (11.4±5.5%, p = .046), stride length (9.2±4.6%, p = .028), and double support time (-8.1±3.0%, p = .028). In summary, our preliminary data showed 12-session of CDTT decreased double support time during cognitive dual task walking, and MDTT reduced gait variability during motor dual task walking. Different training strategy can be adopted for possibly different training effects in people with PD.

Mutant p53 perturbs DNA replication checkpoint control through TopBP1 and Treslin.

Accumulating evidence supports the gain-of-function of mutant forms of p53 (mutp53s). However, whether mutp53 directly perturbs the DNA replication checkpoint remains unclear. Previously, we have demonstrated that TopBP1 forms a complex with mutp53s and mediates their gain-of-function through NF-Y and p63/p73. Akt phosphorylates TopBP1 and induces its oligomerization, which inhibits its ATR-activating function. Here we show that various contact and conformational mutp53s bypass Akt to induce TopBP1 oligomerization and attenuate ATR checkpoint response during replication stress. The effect on ATR response caused by mutp53 can be exploited in a synthetic lethality strategy, as depletion of another ATR activator, DNA2, in mutp53-R273H-expressing cancer cells renders cells hypersensitive to cisplatin. Expression of mutp53-R273H also makes cancer cells more sensitive to DNA2 depletion or DNA2 inhibitors. In addition to ATR-activating function during replication stress, TopBP1 interacts with Treslin in a Cdk-dependent manner to initiate DNA replication during normal growth. We find that mutp53 also interferes with TopBP1 replication function. Several contact, but not conformational, mutp53s enhance the interaction between TopBP1 and Treslin and promote DNA replication despite the presence of a Cdk2 inhibitor. Together, these data uncover two distinct mechanisms by which mutp53 enhances DNA replication: (i) Both contact and conformational mutp53s can bind TopBP1 and attenuate the checkpoint response to replication stress, and (ii) during normal growth, contact (but not conformational) mutp53s can override the Cdk2 requirement to promote replication by facilitating the TopBP1/Treslin interaction.

Regulation of RNF144A E3 Ubiquitin Ligase Activity by Self-association through Its Transmembrane Domain.

RNF144A, an E3 ubiquitin ligase for DNA-dependent protein kinase catalytic subunit (DNA-PKcs), can promote DNA damage-induced cell apoptosis. Here we characterize an important regulation of RNF144A through its transmembrane (TM) domain. The TM domain of RNF144A is highly conserved among species. Deletion of the TM domain abolishes its membrane localization and also significantly reduces its ubiquitin ligase activity. Further evidence shows that the TM domain is required for RNF144A self-association and that the self-association may be partially mediated through a classic GXXXG interaction motif. A mutant RNF144A-G252L/G256L (in the G(252)XXXG(256) motif) preserves membrane localization but is defective in self-association and ubiquitin ligase activity. On the other hand, a membrane localization loss mutant of RNF144A still retains self-association and E3 ligase activity, which can be blocked by additional G252L/G256L mutations. Therefore, our data demonstrate that the TM domain of RNF144A has at least two independent roles, membrane localization and E3 ligase activation, to regulate its physiological function. This regulatory mechanism may be applicable to other RBR (RING1-IBR-RING2) E3 ubiquitin ligases because, first, RNF144B also self-associates. Second, all five TM-containing RBR E3 ligases, including RNF144A and RNF144B, RNF19A/Dorfin, RNF19B, and RNF217, have the RBR-TM(GXXXG) superstructure. Mutations of the GXXXG motifs in RNF144A and RNF217 have also be found in human cancers, including a G252D mutation of RNF144A. Interestingly, RNF144A-G252D still preserves self-association and ubiquitin ligase activity but loses membrane localization and is turned over rapidly. In conclusion, both proper membrane localization and self-association are important for RNF144A function.

RNF144A, an E3 ubiquitin ligase for DNA-PKcs, promotes apoptosis during DNA damage.

Several ring between ring fingers (RBR) -domain proteins, such as Parkin and Parc, have been shown to be E3 ligases involved in important biological processes. Here, we identify a poorly characterized RBR protein, Ring Finger protein 144A (RNF144A), as the first, to our knowledge, mammalian E3 ubiquitin ligase for DNA-PKcs. We show that DNA damage induces RNF144A expression in a p53-dependent manner. RNF144A is mainly localized in the cytoplasmic vesicles and plasma membrane and interacts with cytoplasmic DNA-dependent protein kinase, catalytic subunit (DNA-PKcs). DNA-PKcs plays a critical role in the nonhomologous end-joining DNA repair pathway and provides prosurvival signaling during DNA damage. We show that RNF144A induces ubiquitination of DNA-PKcs in vitro and in vivo and promotes its degradation. Depletion of RNF144A leads to an increased level of DNA-PKcs and resistance to DNA damaging agents, which is reversed by a DNA-PK inhibitor. Taken together, our data suggest that RNF144A may be involved in p53-mediated apoptosis through down-regulation of DNA-PKcs when cells suffer from persistent or severe DNA damage insults.