Protease-mediated processing of Argonaute proteins controls small RNA association.

Small RNA pathways defend the germlines of animals against selfish genetic elements, yet pathway activities need to be contained to prevent silencing of self genes. Here, we reveal a proteolytic mechanism that controls endogenous small interfering (22G) RNA activity in the Caenorhabditis elegans germline to protect genome integrity and maintain fertility. We find that DPF-3, a P-granule-localized N-terminal dipeptidase orthologous to mammalian dipeptidyl peptidase (DPP) 8/9, processes the unusually proline-rich N termini of WAGO-1 and WAGO-3 Argonaute (Ago) proteins. Without DPF-3 activity, these WAGO proteins lose their proper complement of 22G RNAs. Desilencing of repeat-containing and transposon-derived transcripts, DNA damage, and acute sterility ensue. These phenotypes are recapitulated when WAGO-1 and WAGO-3 are rendered resistant to DPF-3-mediated processing, identifying them as critical substrates of DPF-3. We conclude that N-terminal processing of Ago proteins regulates their activity and promotes silencing of selfish genetic elements by ensuring Ago association with appropriate small RNAs.

Non-canonical role for the BAF complex subunit DPF3 in mitosis and ciliogenesis.

DPF3, along with other subunits, is a well-known component of the BAF chromatin remodeling complex, which plays a key role in regulating chromatin remodeling activity and gene expression. Here, we elucidated a non-canonical localization and role for DPF3. We showed that DPF3 dynamically localizes to the centriolar satellites in interphase and to the centrosome, spindle midzone and bridging fiber area, and midbodies during mitosis. Loss of DPF3 causes kinetochore fiber instability, unstable kinetochore-microtubule attachment and defects in chromosome alignment, resulting in altered mitotic progression, cell death and genomic instability. In addition, we also demonstrated that DPF3 localizes to centriolar satellites at the base of primary cilia and is required for ciliogenesis by regulating axoneme extension. Taken together, these findings uncover a moonlighting dual function for DPF3 during mitosis and ciliogenesis.

Pioneering EBF2 remodels the brown fat chromatin landscape.

In this issue of Genes & Development, Shapira and colleagues (pp. 660-673) outline mechanisms by which the brown fat transcription factor early B-cell factor 2 (EBF2) selectively activates brown lineage-specific gene expression. The investigators show that EBF2 interacts with and recruits a tissue-specific BAF chromatin remodeling complex to brown fat gene enhancers, thereby regulating chromatin accessibility. Their findings provide important insight into epigenetic regulation of adipocyte fate and thermogenic gene expression.

EBF2 transcriptionally regulates brown adipogenesis via the histone reader DPF3 and the BAF chromatin remodeling complex.

The transcription factor early B-cell factor 2 (EBF2) is an essential mediator of brown adipocyte commitment and terminal differentiation. However, the mechanisms by which EBF2 regulates chromatin to activate brown fat-specific genes in adipocytes were unknown. ChIP-seq (chromatin immunoprecipitation [ChIP] followed by deep sequencing) analyses in brown adipose tissue showed that EBF2 binds and regulates the activity of lineage-specific enhancers. Mechanistically, EBF2 physically interacts with the chromatin remodeler BRG1 and the BAF chromatin remodeling complex in brown adipocytes. We identified the histone reader protein DPF3 as a brown fat-selective component of the BAF complex that was required for brown fat gene programming and mitochondrial function. Loss of DPF3 in brown adipocytes reduced chromatin accessibility at EBF2-bound enhancers and led to a decrease in basal and catecholamine-stimulated expression of brown fat-selective genes. Notably, Dpf3 is a direct transcriptional target of EBF2 in brown adipocytes, thereby establishing a regulatory module through which EBF2 activates and also recruits DPF3-anchored BAF complexes to chromatin. Together, these results reveal a novel mechanism by which EBF2 cooperates with a tissue-specific chromatin remodeling complex to activate brown fat identity genes.

Meeting report: Xenotransplantation Development Conference in Neijiang, China.

A conference on progress in the development of xenotransplantation in China was held in Neijiang, Sichuan, in May 2023, and was attended by approximately 100 established researchers and trainees. Progress in xenotransplantation research was reviewed by both Chinese and foreign experts. The topics discussed ranged from genetic engineering of pigs and the results of pig-to-nonhuman primate organ transplantation to the requirements for designated pathogen-free (DPF) pig facilities and regulation of xenotransplantation. This conference served as an opportunity to collectively advance the development of xenotransplantation in China and pave the way for its clinical application.

Characteristics of Resistive PM Sensors for Onboard Diagnostics of Diesel Particulate Filter Failure.

In accordance with the recently reinforced exhaust regulations and onboard diagnostics regulations, it is essential to adopt diesel particulate filter systems in diesel vehicles; a sensor that directly measures particulate matter (PM) in exhaust gas is installed to precisely monitor diesel particulate filter (DPF) failure. Because the reduction of particulate matter in the diesel particulate filter system is greatly influenced by the physical wall structure of the substrate, the presence or absence of damage to the substrate wall (cracks or local melting, etc.) determines the reliability of normal DPF operation. Therefore, an onboard diagnostics sensor for particle matter is being developed with a focus on monitoring damage to the DPF wall. In this study, as a sensor for determining damage to the substrate wall, an accumulation-type sensor whose resistance changes as soot particles are deposited between two electrodes was fabricated. The sensor characteristics were investigated by changing the gap between the sensor electrodes, sensor cap shape, and electrode bias voltage to improve resistive soot sensor sensitivity and response. From the signal characteristics of various sensor configurations, a combination sensor with improved signal stability and response time is manufactured, and they were compared with the characteristics of commercially available sensors in the engine-simulated NEDC mode in terms of the degree of DPF crack. As a result of transient mode, PM monitoring cycle was improved by 1.2~1.5 times during the same vehicle driving time compared to the existing commercial sensor.

Unveiling the Metal-Dependent Aggregation Properties of the C-terminal Region of Amyloidogenic Intrinsically Disordered Protein Isoforms DPF3b and DPF3a.

Double-PHD fingers 3 (DPF3) is a BAF-associated human epigenetic regulator, which is increasingly recognised as a major contributor to various pathological contexts, such as cardiac defects, cancer, and neurodegenerative diseases. Recently, we unveiled that its two isoforms (DPF3b and DPF3a) are amyloidogenic intrinsically disordered proteins. DPF3 isoforms differ from their C-terminal region (C-TERb and C-TERa), containing zinc fingers and disordered domains. Herein, we investigated the disorder aggregation properties of C-TER isoforms. In agreement with the predictions, spectroscopy highlighted a lack of a highly ordered structure, especially for C-TERa. Over a few days, both C-TERs were shown to spontaneously assemble into similar antiparallel and parallel ß-sheet-rich fibrils. Altered metal homeostasis being a neurodegeneration hallmark, we also assessed the influence of divalent metal cations, namely Cu2+, Mg2+, Ni2+, and Zn2+, on the C-TER aggregation pathway. Circular dichroism revealed that metal binding does not impair the formation of ß-sheets, though metal-specific tertiary structure modifications were observed. Through intrinsic and extrinsic fluorescence, we found that metal cations differently affect C-TERb and C-TERa. Cu2+ and Ni2+ have a strong inhibitory effect on the aggregation of both isoforms, whereas Mg2+ impedes C-TERb fibrillation and, on the contrary, enhances that of C-TERa. Upon Zn2+ binding, C-TERb aggregation is also hindered, and the amyloid autofluorescence of C-TERa is remarkably red-shifted. Using electron microscopy, we confirmed that the metal-induced spectral changes are related to the morphological diversity of the aggregates. While metal-treated C-TERb formed breakable and fragmented filaments, C-TERa fibrils retained their flexibility and packing properties in the presence of Mg2+ and Zn2+ cations.

Mutations in the BAF-Complex Subunit DPF2 Are Associated with Coffin-Siris Syndrome.

Variants affecting the function of different subunits of the BAF chromatin-remodelling complex lead to various neurodevelopmental syndromes, including Coffin-Siris syndrome. Furthermore, variants in proteins containing PHD fingers, motifs recognizing specific histone tail modifications, have been associated with several neurological and developmental-delay disorders. Here, we report eight heterozygous de novo variants (one frameshift, two splice site, and five missense) in the gene encoding the BAF complex subunit double plant homeodomain finger 2 (DPF2). Affected individuals share common clinical features described in individuals with Coffin-Siris syndrome, including coarse facial features, global developmental delay, intellectual disability, speech impairment, and hypoplasia of fingernails and toenails. All variants occur within the highly conserved PHD1 and PHD2 motifs. Moreover, missense variants are situated close to zinc binding sites and are predicted to disrupt these sites. Pull-down assays of recombinant proteins and histone peptides revealed that a subset of the identified missense variants abolish or impaire DPF2 binding to unmodified and modified H3 histone tails. These results suggest an impairment of PHD finger structural integrity and cohesion and most likely an aberrant recognition of histone modifications. Furthermore, the overexpression of these variants in HEK293 and COS7 cell lines was associated with the formation of nuclear aggregates and the recruitment of both wild-type DPF2 and BRG1 to these aggregates. Expression analysis of truncating variants found in the affected individuals indicated that the aberrant transcripts escape nonsense-mediated decay. Altogether, we provide compelling evidence that de novo variants in DPF2 cause Coffin-Siris syndrome and propose a dominant-negative mechanism of pathogenicity.

Conserved Structure and Evolution of DPF Domain of PHF10-The Specific Subunit of PBAF Chromatin Remodeling Complex.

Transcription activation factors and multisubunit coactivator complexes get recruited at specific chromatin sites via protein domains that recognize histone modifications. Single PHDs (plant homeodomains) interact with differentially modified H3 histone tails. Double PHD finger (DPF) domains possess a unique structure different from PHD and are found in six proteins: histone acetyltransferases MOZ and MORF; chromatin remodeling complex BAF (DPF1-3); and chromatin remodeling complex PBAF (PHF10). Among them, PHF10 stands out due to the DPF sequence, structure, and functions. PHF10 is ubiquitously expressed in developing and adult organisms as four isoforms differing in structure (the presence or absence of DPF) and transcription regulation functions. Despite the importance of the DPF domain of PHF10 for transcription activation, its structure remains undetermined. We performed homology modeling of the human PHF10 DPF domain and determined common and distinct features in structure and histone modifications recognition capabilities, which can affect PBAF complex chromatin recruitment. We also traced the evolution of DPF1-3 and PHF10 genes from unicellular to vertebrate organisms. The data reviewed suggest that the DPF domain of PHF10 plays an important role in SWI/SNF-dependent chromatin remodeling during transcription activation.

Modelling the Influence of Different Soot Types on the Radio-Frequency-Based Load Detection of Gasoline Particulate Filters.

Gasoline particulate filters (GPFs) are an appropriate means to meet today's emission standards. As for diesel applications, GPFs can be monitored via differential pressure sensors or using a radio-frequency approach (RF sensor). Due to largely differing soot properties and engine operating modes of gasoline compared to diesel engines (e.g., the possibility of incomplete regenerations), the behavior of both sensor systems must be investigated in detail. For this purpose, extensive measurements on engine test benches are usually required. To simplify the sensor development, a simulation model was developed using COMSOL Multiphysics® that not only allowed for calculating the loading and regeneration process of GPFs under different engine operating conditions but also determined the impact on both sensor systems. To simulate the regeneration behavior of gasoline soot accurately, an oxidation model was developed. To identify the influence of different engine operating points on the sensor behavior, various samples generated at an engine test bench were examined regarding their kinetic parameters using thermogravimetric analysis. Thus, this compared the accuracy of soot mass determination using the RF sensor with the differential pressure method. By simulating a typical driving condition with incomplete regenerations, the effects of the soot kinetics on sensor accuracy was demonstrated exemplarily. Thereby, the RF sensor showed an overall smaller mass determination error, as well as a lower dependence on the soot kinetics.

[Effects of Different Chemoradiotherapy Regimens on Early Survival Outcomes in Patients with Locally Advanced Nasopharyngeal Carcinoma].

OBJECTIVE: To compare the early survival outcomes of patients with locally advanced nasopharyngeal carcinoma received EPF (epirubicin, cisplatin and fluorouracil) induced chemotherapy combined with concurrent nimotuzumab with radiotherapy (CNRT) or DPF (docetaxel, cisplatin and fluorouracil) induced chemotherapy combined with concurrent chemoradiotherapy (CCRT). METHODS: Patients with locally advanced nasopharyngeal carcinoma (stage Ⅲ to Ⅳb) from March 2010 to September 2017 were included. The primary endpoint was disease-free survival (DFS). The secondary endpoints were distant metastasis-free survival (DMFS), local recurrence-free survival (LRFS), and overall survival (OS). Propensity score matching was used to balance the differences in clinical characteristics between the two groups. Kaplan-Meier method and log-rank test were used to compare the survival differences between the two groups. Multivariate Cox proportional hazards model was used to identify potential prognostic factors. RESULTS: After matching, a total of 153 patients were enrolled, including 51 patients in the EPF combined with CNRT group and 102 patients in the DPF combined with CCRT group. There was no difference in 2-year DFS (82.4% vs. 85.3%, P=0.880), OS (88.2% vs. 96.0%, P=0.410), LRFS (100.0% vs. 92.1%, P=0.278), and DMFS (82.3% vs. 88.2%, P=0.120) between EPF combined with CNRT group and DPF combined with CCRT group. Treatment regimen (EPF combined with CNRT vs. DPF combined with CCRT) was not an independent prognostic factor of DFS (hazard ratio (HR)=0.530, P=0.075). In the subgroup analyses, EPF combined with CNRT could reduce the risk of disease progression in T3 (HR=0.174, P=0.045), N1/N2 (HR=0.432, P=0.036), and male patients (HR=0.437, P=0.044). During concurrent radiotherapy, the incidence of grade 3-4 neutropenia in EPF combined with CNRT was significantly lower than that of DPF combined with CCRT (P=0.007). CONCLUSION: EPF combined with CNRT regimen is similar to DPF combined with CCRT regimen in survival outcomes, but the patients with T3, N1/N2, and male nasopharyngeal carcinoma may benefit from EPF combined with CNRT regimen.

Downregulation of DPF3 promotes the proliferation and motility of breast cancer cells through activating JAK2/STAT3 signaling.

It is reported that the genetic variation of DPF3 is a risk factor of breast cancer through large-scale association research. However, the expression, function and mechanism in breast cancer is unknown. We applied qPCR and western blotting to detect the levels of DPF3 in breast cancer tissues. MTT and Anchorage-independent growth ability assay were used to evaluate the effect of DPF3 on cell proliferation. Wound healing and transwell invasion assay were performed to detect the role of DPF3 on cell motility ability. Herein, we found that the mRNA and protein levels of DPF3 are both significantly downregulated in breast cancer tissues. And downregulation of DPF3 can promote the proliferation and motility of breast cancer cells. Further investigation illustrated that downregulation of DPF3 can activate the JAK2/STAT3 signaling. In conclusion, we found that the downregulation of DPF3 plays an indispensable function in the progression of breast cancer, and may be served as a novel therapeutic target to therapy breast cancer.

Uncertainties in Model-Based Diesel Particulate Filter Diagnostics Using a Soot Sensor.

Monitoring the filtration efficiency of the diesel particulate filter (DPF), is a legislative requirement for minimizing particulate matter (PM) emissions from diesel engines of passenger cars and heavy-duty vehicles. To reach this target, on-board diagnostics (OBD) in real-time operation are required. Such systems in passenger cars are often utilizing a soot sensor, models for PM emissions simulation and algorithms for diagnosis. Their performance is associated with a series of challenges related to the accuracy and effectiveness of involved models, algorithms and hardware. This paper analyzes the main influencing factors and their impact on the effectiveness of the OBD system. The followed method comprised an error propagation analysis to quantify the error of detection during a New European Driving Cycle (NEDC). The results of the study regarding the performance of the OBD model showed that the total error of diagnosis is ±28%. This performance can be improved by increasing the sensor accuracy and the soot model, which can make the model appropriate for even tighter legislation limits and other approaches such as on-board monitoring (OBM).

Double Plant Homeodomain Fingers 2 (DPF2) Promotes the Immune Escape of Influenza Virus by Suppressing Beta Interferon Production.

The high mutation rates of the influenza virus genome facilitate the generation of viral escape mutants, rendering vaccines and drugs against influenza virus-encoded targets potentially ineffective. Therefore, we identified host cell determinants dispensable for the host but crucial for virus replication, with the goal of preventing viral escape and finding effective antivirals. To identify these host factors, we screened 2,732 human genes using RNA interference and focused on one of the identified host factors, the double plant homeodomain fingers 2 (DPF2/REQ) gene, for this study. We found that knockdown of DPF2 in cells infected with influenza virus resulted in decreased expression of viral proteins and RNA. Furthermore, production of progeny virus was reduced by two logs in the multiple-cycle growth kinetics assay. We also found that DPF2 was involved in the replication of seasonal influenza A and B viruses. Because DPF2 plays a crucial role in the noncanonical NF-κB pathway, which negatively regulates type I interferon (IFN) induction, we examined the relationship between DPF2 and IFN responses during viral infection. The results showed that knockdown of DPF2 resulted in increased expression of IFN-ß and induced phosphorylation of STAT1 in infected cells. In addition, high levels of several cytokines/chemokines (interleukin-8 [IL-8], IP-10, and IL-6) and antiviral proteins (MxA and ISG56) were produced by DPF2 knockdown cells. In conclusion, we identified a novel host factor, DPF2, that is required for influenza virus to evade the host immune response and that may serve as a potential antiviral target.IMPORTANCE Influenza virus is responsible for seasonal epidemics and occasional pandemics and is an ongoing threat to public health worldwide. Influenza virus relies heavily on cellular factors to complete its life cycle. Here we identified a novel host factor, DPF2, which is involved in influenza virus infection. Our results showed that DPF2 plays a crucial role in the replication and propagation of influenza virus. DPF2 functions in the noncanonical NF-κB pathway, which negatively regulates type I IFN induction. Thus, we investigated the relationship between the IFN response and DPF2 in influenza virus infection. Upon influenza virus infection, DPF2 dysregulated IFN-ß induction and expression of cytokines/chemokines and antiviral proteins. This study provides evidence that influenza virus utilizes DPF2 to escape host innate immunity.

Pathogen elimination and prevention within a regulated, Designated Pathogen Free, closed pig herd for long-term breeding and production of xenotransplantation materials.

BACKGROUND: We established a Source Animal (barrier) Facility (SAF) for generating designated pathogen-free (DPF) pigs to serve as donors of viable organs, tissues, or cells for xenotransplantation into clinical patients. This facility was populated with caesarian derived, colostrum deprived (CDCD) piglets, from sows of conventional-specific (or specified) pathogen-free (SPF) health status in six cohorts over a 10-month period. In all cases, CDCD piglets fulfilled DPF status including negativity for porcine circovirus (PCV), a particularly environmentally robust and difficult to inactivate virus which at the time of SAF population was epidemic in the US commercial swine production industry. Two outbreaks of PCV infection were subsequently detected during sentinel testing. The first occurred several weeks after PCV-negative animals were moved under quarantine from the nursery into an animal holding room. The apparent origin of PCV was newly installed stainless steel penning, which was not sufficiently degreased thereby protecting viral particles from disinfection. The second outbreak was apparently transmitted via employee activities in the Caesarian-section suite adjacent to the barrier facility. In both cases, PCV was contained in the animal holding room where it was diagnosed making a complete facility depopulation-repopulation unnecessary. METHOD: Infectious PCV was eliminated during both outbreaks by the following: euthanizing infected animals, disposing of all removable items from the affected animal holding room, extensive cleaning with detergents and degreasing agents, sterilization of equipment and rooms with chlorine dioxide, vaporized hydrogen peroxide, and potassium peroxymonosulfate, and for the second outbreak also glutaraldehyde/quaternary ammonium. Impact on other barrier animals throughout the process was monitored by frequent PCV diagnostic testing. RESULT: After close monitoring for 6 months indicating PCV absence from all rooms and animals, herd animals were removed from quarantine status. CONCLUSION: Ten years after PCV clearance following the second outbreak, due to strict adherence to biosecurity protocols and based on ongoing sentinel diagnostic monitoring (currently monthly), the herd remains DPF including PCV negative.

DPFF-1 transcription factor deficiency causes the aberrant activation of MPK-1 and meiotic defects in the Caenorhabditis elegans germline.

The d4 family of transcription factors consists of three members in mammals. DPF1/neuro-d4 is expressed mainly in neurons and the peripheral nervous system, and is important for brain development. DPF2/requiem/ubi-d4 is expressed ubiquitously and presumably functions as an apoptotic factor, especially during the deprivation of trophic factors. DPF3/cer-d4 is expressed in neurons and in the heart, and is important for heart development and function in zebrafish. In Drosophila, there is only one member, dd4, whose function is still unknown, but it is expressed in many tissues and is particularly abundant in the brain of developing embryos and in adults. Here, we present DPFF-1, the only member of this family of proteins in the nematode C. elegans. DPFF-1 is similar to its mammalian homolog DPF2/requiem/ubi-d4 because it is ubiquitously expressed during embryogenesis and in adult tissues, and because it is important for the induction of germ cell apoptosis during stress. Here, we show that dpff-1 null mutant animals produce less progeny than wild-type nematodes, presumably due to meiotic defects. Gonads of dpff-1 deficient animals showed more germ cells in pachytene and overexpressed the P-MPK-1 signal. Additionally, these animals presented higher levels of p53-induced germ cell apoptosis than wild-type animals. Furthermore, we observed that dpff-1 deficient animals are more sensitive to heat shock. This is the first report showing that the d4 family of transcription factors could be involved in meiosis and stress protection.

Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts.

Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies to determine the soot load of the filters and to measure particulate matter concentrations in the exhaust gas during vehicle operation are highly needed. In this study, different approaches for soot sensing are compared. Measurements were conducted on a dynamometer diesel engine test bench with a diesel particulate filter (DPF). The DPF was monitored by a relatively new microwave-based approach. Simultaneously, a resistive type soot sensor and a Pegasor soot sensing device as a reference system measured the soot concentration exhaust upstream of the DPF. By changing engine parameters, different engine out soot emission rates were set. It was found that the microwave-based signal may not only indicate directly the filter loading, but by a time derivative, the engine out soot emission rate can be deduced. Furthermore, by integrating the measured particulate mass in the exhaust, the soot load of the filter can be determined. In summary, all systems coincide well within certain boundaries and the filter itself can act as a soot sensor.

Crystal structure of DPF3b in complex with an acetylated histone peptide.

Histone acetylation plays an important role in chromatin dynamics and is associated with active gene transcription. This modification is written by acetyltransferases, erased by histone deacetylases and read out by bromodomain containing proteins, and others such as tandem PHD fingers of DPF3b. Here we report the high resolution crystal structure of the tandem PHD fingers of DPF3b in complex with an H3K14ac peptide. In the complex structure, the histone peptide adopts an α-helical conformation, unlike previously observed by NMR, but similar to a previously reported MOZ-H3K14ac complex structure. Our crystal structure adds to existing evidence that points to the α-helix as a natural conformation of histone tails as they interact with histone-associated proteins.

DPF2 regulates OCT4 protein level and nuclear distribution.

The amount of transcription factor OCT4 is strictly regulated. A tight regulation of OCT4 levels is crucial for mammalian embryonic development and oncogenesis. However, the mechanisms underlying regulation of OCT4 protein expression and nuclear distribution are largely unknown. Here, we report that DPF2, a plant homeodomain (PHD) finger protein, is upregulated during H9 cell differentiation induced by retinoic acid. Endogenous interaction between DPF2 and OCT4 in P19 cells was revealed by an immunoprecipitation assay. GST-pull down assay proved that OCT4 protein in H9 cells and recombinant OCT4 can precipitate with DPF2 in vitro. In vitro ubiquitination assay demonstrated DPF2 might serve as an E3 ligase. Knock down of dpf2 using siRNA increased OCT4 protein level and stability in P19 cells. DPF2 siRNAs also up-regulates OCT4 but not NANOG in H9 cells. However, RA fails to downregulates OCT4 protein level in cells infected by lenitviruses containing DPF2 siRNA. Moreover, overexpression of both DPF2 and OCT4 in 293 cells proved the DPF2-OCT4 interaction. DPF2 but not PHD2 mutant DPF2 enhanced ubiquitination and degradation of OCT4 in 293 cells co-expressed DPF2 and OCT4. Both wild type DPF2 and PHD2 mutant DPF2 redistributes nuclear OCT4 without affecting DPF2-OCT4 interaction. Further analysis indicated that DPF2 decreases monomeric and mono-ubiquitinated OCT4, assembles poly-ubiquitin chains on OCT4 mainly through Ub-K48 linkage. These findings contribute to an understanding of how OCT4 protein level and nuclear distribution is regulated by its associated protein.