Risk factors for early onset patellofemoral osteoarthritis following anterior cruciate ligament reconstruction with hamstring tendon autograft.

OBJECTIVE: This study aimed to identify risk factors contributing to the early onset of patellofemoral osteoarthritis (PFOA) within the first two years following anterior cruciate ligament reconstruction (ACLR) using a hamstring tendon autograft. METHODS: Participants aged 18 to 40 who had undergone ACLR within the past two years were included in this study, along with a control group of healthy volunteers. Magnetic resonance imaging (MRI) data were obtained preoperatively, at two years postoperatively, and from the control group. T-tests were used to assess differences in patellofemoral alignment (PA) and trochlear morphology (TM) between the pre- and post-ACLR patients and healthy controls. The incidence of PFOA was recorded, and associations between PA, TM, and clinical parameters were evaluated in patients with and without PFOA. Logistic regression analysis was conducted to identify potential risk factors for PFOA development. RESULTS: A total of 177 patients, with a mean follow-up period of 22.17 ± 5.09 months and a mean age of 26.4 ± 5.6 years, were included in the study. Following ACL injury, significant alterations in patellar tilt angle (PTA), tuberositas tibae-trochlear groove distance (TT-TG), Insall-Salvati ratio (ISR), and static anterior tibial translation (SATT) were observed compared to the control group. Postoperatively, deviations in PTA and SATT remained significant when compared to healthy controls. Of the 177 patients, 68 (38.42%) developed early-onset PFOA. Factors associated with the early onset of PFOA included age at the time of surgery, the interval between injury and surgery, PTA, bisect offset (BO), sulcus angle (SA), thigh circumference, SATT, and partial meniscectomy. CONCLUSION: Significant differences in PTA, TT-TG, ISR, and SATT were identified between patients who underwent ACLR and healthy controls. Postoperatively, there was no correction in PTA or SATT, which remained significantly altered. Factors such as age at the time of surgery, PTA, BO, SA, ISR, SATT, thigh circumference, partial meniscectomy, and the time interval between injury and surgery were associated with the early onset of PFOA within two years post-ACLR. These findings may aid in the prevention of PFOA by identifying individuals at higher risk for early development.

Preparation and Hepatoprotective Activities of Peptides Derived from Mussels (Mytilus edulis) and Clams (Ruditapes philippinarum).

Low molecular weight (<5 kDa) peptides from mussels (Mytilus edulis) (MPs) and the peptides from clams (Ruditapes philippinarum) (CPs) were prepared through enzymatic hydrolysis by proteases (dispase, pepsin, trypsin, alcalase and papain). Both the MPs and the CPs showed excellent in vitro scavenging ability of free radicals including OH, DPPH and ABTS in the concentration range of 0.625−10.000 mg/mL. By contrast, the MPs hydrolyzed by alcalase (MPs-A) and the CPs hydrolyzed by dispase (CPs-D) had the highest antioxidant activities. Furthermore, MPs-A and CPs-D exhibited protective capabilities against oxidative damage induced by H2O2 in HepG2 cells in the concentration range of 25−800 µg/mL. Meanwhile, compared with the corresponding indicators of the negative control (alcohol-fed) mice, lower contents of hepatic MDA and serums ALT and AST, as well as higher activities of hepatic SOD and GSH-PX were observed in experiment mice treated with MPs-A and CPs-D. The present results clearly indicated that Mytilus edulis and Ruditapes philippinarum are good sources of hepatoprotective peptides.

[Hepatic Insulin Resistance and Type 2 Diabetes Mellitus].

Insulin resistance (IR) is a pathological reaction of hyperinsulinemia and impaired glucose tolerance caused by decreased sensitivity of target tissues such as liver to insulin.The pathogenesis of IR as a typical pathological feature of type 2 diabetes is the focus of anti-diabetes research.In this paper,we reviewed the molecular mechanisms of glucose and lipid metabolism,oxidative stress,mitochondrial dysfunction,endoplasmic reticulum stress,inflammation,and hepatic IR in the case of type 2 diabetes mellitus,which might provide new ideas and theoretical guidance for the treatment of diabetes mellitus.

[Research progress and analysis on mechanism of polysaccharides against type 2 diabetes mellitus].

Polysaccharides are macromolecular compounds formed by more than 10 monosaccharide molecules linked by glycosidic bonds. Polysaccharides have a wide range of sources, high safety and low toxicity, with a variety of biological activities, such as anti-tumor, anti-virus, immune regulation, lowering blood glucose, and lowering blood lipids. Type 2 diabetes mellitus(T2 DM) is a chronic metabolic disorder characterized by hyperglycemia, insulin resistance and low inflammation. In recent years, the treatment of T2 DM with polysaccharide has become a research hotspot. Polysaccharides can not only make up for the side effects such as hypoglycemia, weight gain, gastrointestinal injury caused by long-term treatment of acarbose, biguanidine and sulfonylurea, but also play an effective role in reducing glucose by regulating glucose metabolism, oxidative stress, inflammatory response, intestinal flora, etc. In this paper, the research progress of polysaccharides in the treatment of T2 DM was reviewed. In addition, the hot spots such as the hypoglycemic activity of polysaccharides with structural modifications were summarized, providing theoretical guidance for the development of active polysaccharide hypoglycemic medicines and the further study of action mechanism.

Association between anemia and outcome in patients hospitalized for acute heart failure syndromes: findings from Beijing Acute Heart Failure Registry (Beijing AHF Registry).

Whether the anemia increases the risk of mortality in patients with acute heart failure (AHF) remains unclear. This study aims to explore the relationship between anemia and outcomes in patients with AHF including subgroup analysis. This study included 3279 patients with hemoglobin available from the Beijing Acute Heart Failure Registry (Beijing AHF Registry) study. The primary endpoint was all-cause mortality in 1 year, and the secondary endpoint was 1-year all-cause events including all-cause death and readmission. Logistic regression models were applied to describe related variables of anemia in patients with AHF. Multivariate Cox proportional hazards models described associations of anemia with clinical outcomes in the overall cohort and subgroups. 45.4% of the patients were found anemic. They were older and had more comorbidities than non-anemic patients. Variables including older age, female, chronic kidney dysfunction (CKD), lower hematocrit, lower albumin, with loop diuretics applied, without beta-blockers, angiotensin-converting enzyme inhibitors /angiotensin receptor blockers (ACEIs/ARBs) and spironolactone applied in the emergency department (ED) were associated with anemia in AHF patients. Anemic patients had higher 1-year mortality (38.4% vs. 27.2%, p < 0.0001) and 1-year events rates (63.2% vs. 56.7%, p < 0.0001). After adjusted for covariates, anemia was associated with the increase of 1-year mortality (hazard ratio [HR] 1.278; 95% confidence interval [CI] 1.114-1.465; p = 0.0005) and 1-year events (HR 1.136; 95% CI 1.025-1.259; p = 0.0154). The severer anemia patients had higher risks both of 1-year mortality and events. In the subgroup analysis, the independent associations of anemia with 1-year mortality were shown in the subgroups including age < 75 years, male, body mass index < 25 kg/m2 and BMI ≥ 25 kg/m2, New York Heart Association (NYHA) functional class I-II and NYHA functional class III-IV, with and without cardiovascular ischemia, heart rate (HR) < 100 bpm and HR ≥ 100 bpm, systolic blood pressure (SBP) < 120 mmHg and SBP ≥ 120 mmHg, left ventricular ejection fraction (LVEF) < 40% and LVEF ≥ 40%, serum creatinine (Scr) < 133 umol/l, and with diuretics use, with and without beta-blockers use, without ACEIs/ARBs use in the ED. Anemia is associated with older age, female, CKD, volume overload, malnutrition, with loop diuretics, without beta-blockers, ACEIs/ARBs and spironolactone administration, and higher mortality and readmission in AHF. The risk associations are particular significantly obvious in younger, male, overweight, preserved LVEF, lower Scr, with diuretics and beta-blockers, without ACEIs/ARBs administration subgroups.Clinical trial No. ChiCTR-RIC-17014222.

Endometrial TGF-ß, IL-10, IL-17 and autophagy are dysregulated in women with recurrent implantation failure with chronic endometritis.

BACKGROUND: Chronic endometritis (CE) is a condition which results in reduced receptivity of embryos by dysregulated lymphocyte subsets, abnormal expression of cytokines, chemokines and other regulatory molecules in the endometrium (EM). Macroautophagy (autophagy), the highly conserved cellular homeostasis pathway, plays an essential role in the development and function of T lymphocytes, and supports T cell lineage stability and survival fitness. The possible relationships between autophagy and local cytokine milieus in repeated implantation failure (RIF) with CE have not been elucidated yet. METHODS: This case-control study was performed at a large reproductive medicine center between February 2015 and July 2016. Seventy-five recurrent implantation falliure women with CE who had "strawberry aspect" and 75 women with male factor infertility were included. In this study, endometrial expressions of IL-17, IL-10, TGF-ß and autophagy related molecules, including LC3-II and mTORC1 were investigated by qRT-PCR, Western blot, immunofluorescence and immunohistochemistry assays. RESULTS: The expression of IL-17 was significantly higher in patients with CE compared to women with male factor infertility, while the expressions of IL-10 and TGF-ß were significantly lower. Moreover, the expression of autophagy (LC3-II) is increased, while the expression of mTORC1 was impaired. CONCLUSIONS: CE is associated with shifted cytokine milieu towards Th17 over Treg immunity in endometrium through impaired autophagy by decreased mTORC1.

An in silico analysis of human sperm genes associated with asthenozoospermia and its implication in male infertility.

Asthenozoospermia is the most common clinical symptom of male infertility. Molecular markers associated with asthenozoospermia spermatozoa are scarcely identified. The objective of this study was to screen the differentially expressed genes (DEGs) in asthenozoospermia spermatozoa and assess the underlying bioinformatics roles in regulation of sperm quality.Based on gene expression omnibus (GEO) database, the GSE22331, GSE1133, and GSE4193 expression profile data were downloaded. The DEGs of asthenozoospermia spermatozoa were identified. Germ cell specific genes in DEGs were further screened. Then, gene ontology (GO) and over-representation analysis of DEGs were performed, followed by protein-protein interaction (PPI) network analysis. Expressions of selected genes of TEX11, ADAMTS5, ASRGL1, GMCL1, PGK2, KLHL10 in normozoospermia and asthenozoospermia spermatozoa were identified using real time Reverse Transcription-Polymerase Chain Reaction (RT-PCR).A total of 1323 DEGs were identified, including 1140 down-regulated genes. Twenty one and 96 down-regulated genes were especially expressed in spermatogonia and round spermatids, suggesting their testicular origins and influences on sperm quality. Bioinformatics analysis showed enriched functions of ubiquitin-like protein transferase or protein binding activities in down-regulated genes. Expressions of selected genes were validated by RT-PCR, which was consistent with bioinformatical results.The present study provided a novel insight into the understanding of sperm quality, and a potential method and dataset for the diagnosis and assessment of sperm quality in the event of male infertility.

Divergent synthesis of dual 1,4-dihydropyridines with different substituted patterns from enaminones and aldehydes through domino reactions.

A concise and efficient protocol for the regioselective synthesis of dual 1,4-dihydropyridines with several substituted patterns has been developed from a cascade cyclization of enaminones and aldehydes in different media (EtOH/CH3CN). The one-pot cascade reaction involves at least five reactive sites and generates multiple C-C and C-N bonds. The established protocol explores the chemistry of enaminones by employing their three reactive sites. The method has several advantages including mild conditions, operational simplicity, and high bond-forming efficiency. It may offer promise in a variety of biochemical applications.

Characteristics, Management, and Outcomes of Acute Heart Failure in the Emergency Department: A Multicenter Registry Study with 1-year Follow-up in a Chinese Cohort in Beijing.

BACKGROUND: The emergency department (ED) has a pivotal influence on the management of acute heart failure (AHF), but data concerning current ED management are scarce. This Beijing AHF Registry Study investigated the characteristics, ED management, and short- and long-term clinical outcomes of AHF. METHODS: This prospective, multicenter, observational study consecutively enrolled 3335 AHF patients who visited 14 EDs in Beijing from January 1, 2011, to September 23, 2012. Baseline data on characteristics and management were collected in the EDs. Follow-up data on death and readmissions were collected until November 31, 2013, with a response rate of 92.80%. The data were reported as median (interquartile range) for the continuous variables, or as number (percentage) for the categorical variables. RESULTS: The median age of the enrolled patients was 71 (58-79) years, and 46.84% were women. In patients with AHF, coronary heart disease (43.27%) was the most common etiology, and myocardium ischemia (30.22%) was the main precipitant. Most of the patients in the ED received intravenous treatments, including diuretics (79.28%) and vasodilators (74.90%). Fewer patients in the ED received neurohormonal antagonists, and 25.94%, 31.12%, and 33.73% of patients received angiotensin converting enzyme inhibitors/angiotensin receptor blockers, beta-blockers, and spironolactone, respectively. The proportions of patients who were admitted, discharged, left against medical advice, and died were 55.53%, 33.58%, 7.08%, and 3.81%, respectively. All-cause mortalities at 30 days and 1 year were 15.30% and 32.27%, respectively. CONCLUSIONS: Substantial details on characteristics and ED management of AHF were investigated. The clinical outcomes of AHF patients were dismal. Thus, further investigations of ED-based therapeutic approaches for AHF are needed.

Periodic elevation of regulatory T cells on the day of embryo transfer is associated with better in vitro fertilization outcome.

Treg cells have been shown to be important in maintaining maternofetal tolerance, but the expression of Tregs in assisted reproductive technology (ART) in women on the day of embryo transfer (D0), 5days (D5) and 14days after ET (D14); the related factors influencing the expression levels of Tregs; the proliferation ability and the relevant cytokine epression by Tregs on D14 have not been investigated. In this study, 124 women undergoing in vitro fertilization-intracytoplasmic sperm injection (IVF/ICSI) were enrolled. Early morning fasting blood samples were obtained for the measurement of Tregs and other relevant indicators on the D0, D5and D14days after ET. we showed that the Tregs were increased on D0 and D14 in pregnant women, while there was no obvious fluctuation in non-pregnant women. IL-10 and TGF-ß levels and the expansion of Tregs were significantly higher in successfully pregnant women than in non-pregnant women on D14. The levels of E2, P did not significantly differ between the groups. We suggest that periodic elevation of Tregs on the day of ET was associated with higher embryo implantation rate after ART.

Screening targeted testis­specific genes for molecular assessment of aberrant sperm quality.

Teratospermia is a heterogeneous and complex disorder, which is closely associated with male fertility. Genes and gene products associated with teratospermia may serve as targeted biomarkers that help understand the underlying mechanisms of male infertility; however, systematic information on the subject remains to be elucidated. The present study performed a comparative bioinformatics analysis to identify biomarkers associated with sperm quality, particular focusing on testis­specific biomarkers. A stepwise screening approach identified 1,085 testis/epididymis­specific genes and 3,406 teratospermia­associated genes, resulting in 348 testis­specific genes associated with aberrant sperm quality. These genes were functionally associated with the reproduction process. Gene products corresponding to heat shock protein family A (Hsp70) member 4 like (HSPA4L) and phosphoglycerate kinase 2 were characterized at the cellular level in human testes and ejaculated spermatozoa. HSPA4L expression in sperm was revealed to be associated with sperm quality. The present study provided a novel insight into the understanding of sperm quality, and a potential method for the diagnosis and assessment of sperm quality in the event of male infertility.

Characteristics of testis-specific phosphoglycerate kinase 2 and its association with human sperm quality.

STUDY QUESTION: Is there an association between the expression of phosphoglycerate kinase (PGK) 2 in spermatozoa and sperm quality in both elderly men and young asthenozoospermia patients? SUMMARY ANSWER: Spermatozoa from elderly men and young asthenozoospermia patients show decreased expression of PGK2, which has a close positive relationship with sperm quality. WHAT IS KNOWN ALREADY: PGK1 and PGK2 are involved in spermatogenesis and thought to be related to sperm motility. However, limited information is known about their temporal-spatial expression in human spermatogenesis and their relationship with sperm quality. STUDY DESIGN, SIZE, DURATION: This was a case-control study including 30 healthy young males (aged 28-31 years), 30 elderly men (aged 68-70 years), and 30 asthenozoospermic patients (aged 25-40 years, progressive motility <32%) who donated semen samples. Furthermore, young testes samples were obtained from five fathers (27-33 years old) who had died in car accidents, while aged testes samples were obtained from five elderly fathers (78-82 years old) who were prostate cancer patients. PARTICIPANTS/MATERIALS, SETTING, METHODS: Semen samples from young adults, elderly men and asthenozoospermic patients were prepared, and their parameters were assessed by Computer-Aided Sperm Analysis (CASA). Sperm proteins were extracted for western blot analysis. Immunohistochemistry was used to characterize the cellular localization of PGK1 and PGK2 in testes samples. Sperm immunofluorescence quantification experiments identified the differential expression of PGK1 and PGK2 in sperm from young adults, elderly men and asthenozoospermic patients. Antibodies against PGK1 and PGK2 were used to test their influence on sperm motility and penetration into viscous media. A modified Kremer test using methyl cellulose was adopted to assess sperm function via penetration into viscous media. MAIN RESULTS AND THE ROLE OF CHANCE: Cellular localization analysis showed that PGK1 was mainly expressed in spermatogonia whereas PGK2 was mainly expressed in round spermatids. Expression levels of both PGKs were significantly decreased in the testis with ageing (P < 0.05). Western blot and immunofluorescence quantification showed markedly lower expression of PGK2 (P < 0.05) in sperm from elderly men or asthenozoospermic patients compared sperm from with healthy young men. Sperm functional analysis validated the close relationship between expression of PGK2 and sperm motility (staining percentage, r = 0.60, P < 0.05; intensity, r = 0.59, P < 0.05). Use of an anti-PGK2 antibody on sperm significantly decreased their ability to penetrate into a cervical mucus substitute (P < 0.05). LIMITATIONS, REASONS FOR CAUTION: Before any clinical applications using PGK2 to assess sperm quality can be developed, more cases should be used to evaluate this approach. WIDER IMPLICATIONS OF THE FINDINGS: The study provides new insights into the role of PGKs in male reproduction. The results also indicate that PGK2 is a promising molecular candidate for the assessment of sperm quality and the screening of male contraceptive targets. STUDY FUNDING/COMPETING INTERESTS: This work was supported by grants from the National Natural Science Foundation of China (no. 81300533, 81370013 and 81000277) and Shandong Provincial Natural Science Foundation, China (ZR2013HQ002). The authors declare no competing financial interests.

Proteome profiling of the sperm maturation milieu in the rhesus monkey (Macaca mulatta) epididymis.

The mammalian spermatozoon acquires its fertilising potential during transit through the epididymis, where it interacts with epididymal luminal fluid proteins (the sperm maturation milieu). In order to highlight the epididymal-specific function of the rhesus monkey (Macaca mulatta) in sperm maturation, two-dimensional gel electrophoresis of epididymal luminal fluid proteins was followed by identification by Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry (MALDI-TOF/MS) or MALDI-TOF/TOF and revealed over five hundred spots, comprising 198 non-redundant proteins. Some mass spectrometric data were confirmed by western blotting identification. Some common epididymal fluid proteins were identified, such as clusterin, α-1-antitrypsin, malate dehydrogenase, L-lactate dehydrogenase B, α-1-acid glycoprotein 1 and α-mannosidase. More than 7% of all proteins were anti-oxidative, which might control oxidative stress within the male tract. When compared with bull and human epididymal luminal fluid proteins, those in the rhesus monkey had more overlap with the human, which provides evidence of a close evolutionary relationship between the rhesus monkey and man. This study provides new proteomic information on possible rhesus monkey epididymal functions and novel potential biomarkers for the noninvasive assessment of male fertility.

Comparison of gene expression of the oncogenic Wnt/ß-catenin signaling pathway components in the mouse and human epididymis.

ß-catenin is an integral part of the Wnt signaling pathway and has been linked to tumorigenesis and multiple developmental processes. The high ß-catenin expression with low tumor incidence in the human epididymis is thus intriguing. In the present study, the ß-catenin gene and protein was found to be highly expressed in the murine caput epididymidis, and the protein mainly localized along the lateral plasma membranes of adjacent epithelial cells throughout both human and mouse epididymides. Furthermore, the adult mouse epididymis was found to express almost all the Wnt/ß-catenin signaling pathway genes that were determined previously by our group in the human organ. Despite the differences in epididymal structure, the similar location of ß-catenin and the high concordance of this pathway's components' gene expression in both the adult human and mouse epididymides make the mouse a suitable animal model for studying the anti-tumor mechanism of the epididymis. In addition, both the mRNA and protein expression of ß-catenin shared a similar spatial expression as the mRNA of Ros1, a proto-oncogene and a key developmental regulator of the initial segment of the mouse epididymis. The observations on the parallel temporal expression of ß-catenin and Ros1 during postnatal development raise the possibility that the canonical Wnt signaling pathway has an additional role in the postnatal development of mouse epididymis.

In-depth Proteomic mapping of mouse (Mus musculus) epididymal constructive basis for sperm maturation.

BACKGROUND: The mouse epididymis performs an essential role in sperm maturation, but global protein expression data in mouse epididymis are still lacking. Here, we reported the first in-depth gel-based profiling of mouse epididymis proteome and established a 2-DE map. RESULTS: A total of 832 protein spots were detected in the reproducible gels, and 625 spots corresponding to 355 unique protein entries have been successfully identified by MALDI-TOF-MS. The confidence of proteome data was validated by Western blot. Functional annotations showed that these proteins were mainly related to general metabolism, antioxidant and structural molecule activity. Immunohistochemistry disclosed two structural proteins (myosin regulatory light polypeptide 9 and alpha-2 type I collagen) continuously expressed in the myoid cell since postpartum. CONCLUSION: This study provides a first-draft reference map of the mouse epididymis proteome, which will greatly expand the knowledge of the epididymal structural basis and contribute to the better understanding of those proteins in the process of mouse epididymal sperm maturation.

WITHDRAWN: Comparative proteome analysis of human testis from newborn, young adult, and aged men identified spermatogenesis-associated proteins.

Ahead of Print article withdrawn by publisher.

Aged men share the sperm protein PATE1 defect with young asthenozoospermia patients.

STUDY QUESTION: Does a defect in the human sperm-located protein prostate and testis expressed 1 (PATE1) exist in both aged men and young asthenozoospermia patients? SUMMARY ANSWER: A defect in sperm PATE1 exists in both aged men and young asthenozoospermia patients, and an antibody against PATE1 can decrease human sperm motility and zona-free hamster oocyte penetration. WHAT IS KNOWN ALREADY: Both aged men and young asthenozoospermia patients have poor sperm quality. The PATE1 protein seems to mediate sperm-egg interactions; however, the mechanisms are still unknown. STUDY DESIGN, SIZE, DURATION: This was a case-control study including 60 young fathers (aged 28-32 years) and 60 aged fathers (68-72 years old) who donated semen by masturbation after 7 days of sexual abstinence. Comparative sperm proteome analysis from the young fathers and aged fathers was performed to discover key proteins. The target protein PATE1 was chosen and validated by western blotting and immunohistochemistry. Quantitative assessment of sperm PATE1 protein was performed on sperm from 60 young fathers, 60 aged fathers and 110 young asthenozoospermia patients. Furthermore, an antibody against PATE1 assay was used to test whether PATE1 participated in sperm motility and penetration of zona-free hamster egg. PARTICIPANTS/MATERIALS, SETTING, METHODS: Samples were pooled and separated by two-dimensional gel electrophoresis followed by identification by matrix-assisted laser desorption/ionization time of flight mass spectrometry. Western blotting and immunohistochemistry were used to validate the confidence of proteomic data. Sperm immunofluorescence quantification experiments disclosed whether the aged men indeed shared the same PATE1 defect with 110 young asthenozoospermia patients. The sperm motility test and penetration of zona-free hamster egg assay were performed for PATE1. MAIN RESULTS AND THE ROLE OF CHANCE: Twenty-two sperm proteins with significant differential expression between young adults and aged men were identified (P < 0.05, mean ratio >1.5), including 13 proteins with decreased expressions with aging. Based on bioinformatics, PATE1 was chosen for further study, and exhibited similar changes in expression level and localization on sperm from aged men and young asthenozoospermia patients. Antibody blocking revealed that PATE1 was involved in sperm-egg penetration and sperm motility. LIMITATIONS, REASONS FOR CAUTION: Before any clinical application of PATE1 as a biomarker for the diagnosis of male infertility, more cases should be used to evaluate confidence in this approach. WIDER IMPLICATIONS OF THE FINDINGS: This study revealed a common molecular basis underlying the decline in sperm quality in the natural aging process and in young men with asthenozoospermia. The data should greatly contribute to the development of molecular evaluation of sperm quality, and the diagnosis and treatment of asthenozoospermia. STUDY FUNDING/COMPETING INTERESTS: This work was supported by grants from the National Natural Science Foundation of China (NO. 81300533, 81370013 and 81000277) and Shandong Provincial Natural Science Foundation, China (ZR2013HQ002, ZR2014HQ068). The authors declare no competing financial interests.

Polymerase η suppresses telomere defects induced by DNA damaging agents.

Telomeres at chromosome ends are normally masked from proteins that signal and repair DNA double strand breaks (DSBs). Bulky DNA lesions can cause DSBs if they block DNA replication, unless they are bypassed by translesion (TLS) DNA polymerases. Here, we investigated roles for TLS polymerase η, (polη) in preserving telomeres following acute physical UVC exposure and chronic chemical Cr(VI) exposure, which both induce blocking lesions. We report that polη protects against cytotoxicity and replication stress caused by Cr(VI), similar to results with ultraviolet C light (UVC). Both exposures induce ataxia telangiectasia and Rad3-related (ATR) kinase and polη accumulation into nuclear foci and localization to individual telomeres, consistent with replication fork stalling at DNA lesions. Polη-deficient cells exhibited greater numbers of telomeres that co-localized with DSB response proteins after exposures. Furthermore, the genotoxic exposures induced telomere aberrations associated with failures in telomere replication that were suppressed by polη. We propose that polη's ability to bypass bulky DNA lesions at telomeres is critical for proper telomere replication following genotoxic exposures.