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The ubiquitin (Ub) ligase Parkin has been recognized as a central player in mitophagy. In contrast to its presumed importance in the heart, ablation of Parkin fails to impact homeostatic mitophagy and cardiac function in both young and aging mice, suggesting compensation from other mitochondrial Ub ligases. However, the identities of such additional mitochondrial Ub ligases, as well as their physiological significance in the heart, remain unclear. Here, we demonstrate that Cullin-RING Ub ligase 5 (CRL5) plays a key role in the control of mitochondrial homeostasis in cardiomyocytes. CRL5 belongs to the family of Cullin-RING Ub ligases (CRLs) and consists of the RING box protein RBX2, scaffold protein Cullin 5 (Cul5), and one of 38 substrate receptor proteins. Analysis of the mitochondrial outer membrane-interacting proteome revealed a robust association of CRLs with mitochondria. Pharmacological and genetic perturbations of CRLs inhibited mitochondrial ubiquitination and mitophagy. Subcellular fractionation, live-cell imaging and immunogold electron microscopy further revealed that RBX2 and Cul5, two core components of CRL5, are quickly recruited to mitochondria upon mitochondrial depolarization. Depletion of RBX2 or Cul5 inhibited mitochondrial ubiquitination and turnover, impaired mitochondrial function, and increased cell death in cardiomyocytes. Importantly, RBX2 deficiency did not alter Parkin expression, had a more robust inhibitory effect on mitochondrial ubiquitination compared to Parkin deficiency, and remained effective in the absence of Parkin. Moreover, loss of RBX2 attenuated Parkin-mediated ubiquitination, suggesting its dominant, Parkin-independent actions in mitochondria. In vivo , deletion of RBX2 in adult mouse hearts suppressed mitophagic activity and provoked accumulation of damaged mitochondria in myocardium, leading to rapid development of dilated cardiomyopathy and heart failure. Finally, RBX2 was upregulated in pressure overloaded mouse hearts but downregulated in human failing hearts, further supporting its protective role in the heart. Taken together, our data allow us to propose RBX2-CRL5 as a mitochondrial Ub ligase and a physiological regulator of mitochondrial and cardiac integrity.

Neddylation is a reversible post-translational modification that covalently attaches ubiquitin-like protein NEDD8 to target proteins via NEDD8-specific E1-E2-E3 enzymes. Through regulating the function of various cellular proteins, neddylation impacts diverse cellular processes and disease states. We have previously identified an indispensable role for neddylation in cardiac chamber maturation through sustaining YAP signaling in the developing heart. However, the importance of neddylation in post-mitotic hearts remains unclear. Here we report neddylation as a novel post-translation mechanism regulating mitochondrial homeostasis in adult heart. Inducible deletion of NAE1, a regulatory subunit of NEDD8 E1 enzyme, in adult mouse heart resulted in dilated cardiomyopathy, heart failure, and eventually premature lethality. The severe cardiac phenotype was preceded by accumulation of mitophagic vesicles and mitochondrial elongation, accompanied by pronounced upregulation of mitophagic markers and alterations in mitochondrial dynamics proteins. Moreover, we found that neddylation is required for mitochondrial ubiquitination and turnover. Consequently, pharmacological and genetic inhibition of neddylation accumulated damaged mitochondria, impaired mitochondrial membrane potential, inhibited mitochondrial respiration, and increased cardiomyocyte cell death in both neonatal and adult cardiomyocytes. Mechanistically, neddylation of Cullins is essential for the assembly of a functional multi-subunit Cullin-RING ubiquitin ligase, which appears to mediate mitochondrial ubiquitination following mitochondrial damage. Taken together, our findings suggest that neddylation serves as a novel mechanism surveilling mitochondrial quality and is essential for the function of normal adult heart.

Rationale: The ubiquitin-proteasome system (UPS) and the autophagic-lysosomal pathway are pivotal to proteostasis. Targeting these pathways is emerging as an attractive strategy for treating cancer. However, a significant proportion of patients who receive a proteasome inhibitor-containing regime show cardiotoxicity. Moreover, UPS and autophagic-lysosomal pathway defects are implicated in cardiac pathogenesis. Hence, a better understanding of the cross-talk between the 2 catabolic pathways will help advance cardiac pathophysiology and medicine. Objective: Systemic proteasome inhibition (PSMI) was shown to increase p62/SQSTM1 expression and induce myocardial macroautophagy. Here we investigate how proteasome malfunction activates cardiac autophagic-lysosomal pathway. Methods and Results: Myocardial macroautophagy, TFEB (transcription factor EB) expression and activity, and p62 expression were markedly increased in mice with either cardiomyocyte-restricted ablation of Psmc1 (an essential proteasome subunit gene) or pharmacological PSMI. In cultured cardiomyocytes, PSMI-induced increases in TFEB activation and p62 expression were blunted by pharmacological and genetic calcineurin inhibition and by siRNA-mediated Molcn1 silencing. PSMI induced remarkable increases in myocardial autophagic flux in wild type mice but not p62 null (p62-KO) mice. Bortezomib-induced left ventricular wall thickening and diastolic malfunction was exacerbated by p62 deficiency. In cultured cardiomyocytes from wild type mice but not p62-KO mice, PSMI induced increases in LC3-II flux and the lysosomal removal of ubiquitinated proteins. Myocardial TFEB activation by PSMI as reflected by TFEB nuclear localization and target gene expression was strikingly less in p62-KO mice compared with wild type mice. Conclusions: (1) The activation of cardiac macroautophagy by proteasomal malfunction is mediated by the Mocln1-calcineurin-TFEB-p62 pathway; (2) p62 unexpectedly exerts a feed-forward effect on TFEB activation by proteasome malfunction; and (3) targeting the Mcoln1 (mucolipin1)-calcineurin-TFEB-p62 pathway may provide new means to intervene cardiac autophagic-lysosomal pathway activation during proteasome malfunction.

Grain size is a major determinant of grain yield in sorghum and other cereals. Over 100 quantitative trait loci (QTLs) of grain size have been identified in sorghum. However, no gene underlying any grain size QTL has been cloned. Here, we describe the fine mapping and cloning of one grain size QTL. From an F8 recombinant inbred line population derived from a cross between inbred lines 654 and LTR108, we identified 44 grain size QTLs. One QTL, qTGW1a, was detected consistently on the long arm of chromosome 1 in the span of 4 years. Using the extreme recombinants from an F2:3 fine-mapping population, qTGW1a was delimited within a ~33 kb region containing three predicted genes. One of them, SORBI_3001G341700, predicted to encode a G-protein γ subunit and homologous to GS3 in rice, is likely to be the causative gene for qTGW1a. qTGW1a appears to act as a negative regulator of grain size in sorghum. The functional allele of the putatively causative gene of qTGW1a from inbred line 654 decreased grain size, plant height, and grain yield in transgenic rice. Identification of the gene underlying qTGW1a advances our understanding of the regulatory mechanisms of grain size in sorghum and provides a target to manipulate grain size through genome editing.

From birth to adulthood cardiomyocytes (CMs) undergo a complex maturation process characterized by drastic changes in cell size, ultrastructure, metabolism and gene expression. The molecular mechanisms regulating CM maturation remain poorly defined. Neddylation is a novel post-translational modification that covalently attaches a small ubiquitin-like protein, NEDD8, to target proteins. We found that deletion of NAE1, a critical NEDD8 E1 enzyme that triggers neddylation, in embryonic and perinatal mouse hearts via Nkx2.5 Cre and aMHC Cre , respectively, led to myocardial hypoplasia, heart failure and early lethality. The severe cardiac phenotypes are accompanied by disorganized sarcomere structure and defective fetal-to-adult gene transition, suggesting a possible role for neddylation in CM maturation. To rule out the confounding effect of secondary changes caused by perturbed CM differentiation and cardiac stress response in the mutant hearts, we used AAV9-cTnT-Cre to achieve mosaic knockout of NAE1 in postnatal hearts. High-dose AAV9 deleted NAE1 in 80% CMs and caused heart failure, whereas low-dose AVV9 deleted NAE1 in 30% CMs and preserved heart function. In the context of preserved cardiac function, CMs lacking NAE1 showed severe disrupted transverse tubules (T-tubules) network, which was further exacerbated in hearts with modest dysfunction. In contrast, T-tubule morphology was largely maintained in CMs with intact NAE1 expression from low-dose AAV9 infected hearts, as well as in CMs with deletion of one allele of NAE1, indicating a key, cell-autonomous role of neddylation in T-tubule maturation. Biochemical and histological analyses further revealed dysregulated metabolic and sarcomeric gene expression and disrupted sarcomere ultrastructure in high-dose AAV9 infected hearts, supporting defective CM maturation. In vitro, pharmacological inhibition of neddylation also impaired myofibril assembly in isolated neonatal and adult CMs. Together, our data reveal an important role of neddylation in CM maturation in the developing heart, warranting further investigations of detailed posttranslational mechanisms underlying CM maturation.

Ubiquitin-mediated proteolysis is essential for protein homeostasis, and its defects lead to the development of various cardiomyopathies and heart failure. By reversing the ubiquitination and degradation of target proteins, deubiquitinases (DUBs) play a crucial role in protein homeostasis. However, the importance of DUBs in cardiac pathophysiology is largely unknown. Here we addressed the role of the DUB OTU domain aldehyde binding-1 (OTUB1) in the heart. Bioinformatics analysis reveals an upregulation of OTUB1 in hypertrophic and failing human hearts. In cultured cardiomyocytes, adrenergic agonists induced upregulation and activation of OTUB1. Silencing OTUB1 in repressed adrenergic agonists-induced fetal gene re-activation, protein synthesis and cardiomyocyte hypertrophy. In vivo , mice deficient of OTUB1 in the heart developed dilated cardiomyopathy and heart failure, leading to premature lethality. The severe cardiac phenotype is accompanied by lipid accumulation, ER dilatation, prevalent autophagic vesicles containing ribosomes, as well as dysregulated expression of metabolic and ribosome genes. Delivery of wild-type OTUB1, but not the enzymatic dead mutant, via AAV9 to OTUB1-deficient hearts attenuated cardiac dysfunction and prolonged the lifespan of mice. Mechanistically, loss of OTUB1 suppressed the degradation of Deptor, an inhibitory mTOR regulator, leading to impaired mTOR signaling in cultured cardiomyocytes and mouse hearts. Collectively, these findings suggest OTUB1 is required for physiological cardiac growth by fine-tuning mTOR signaling and identify OTUB1 as a novel regulator of cardiac homeostasis.

Genome editing system based on the CRISPR/Cas (clustered regularly interspaced short palindromic repeats) technology is a milestone for biology. However, public concerns regarding genetically modified organisms (GMOs) and recalcitrance in the crop of choice for regeneration have limited its application. Cell-penetrating peptides (CPPs) are derived from protein transduction domains (PTDs) that can take on various cargoes across the plant wall, and membrane of target cells. Selected CPPs show mild cytotoxicity and are a suitable delivery tool for DNA-free genome editing. Moreover, CPPs may also be applied for the transient delivery of morphogenic transcription factors, also known as developmental regulators (DRs), to overcome the bottleneck of the crop of choice regeneration. In this review, we introduce a brief history of cell-penetrating peptides and discuss the practice of CPP-mediated DNA-free transfection and the prospects of this potential delivery tool for improving crop genome editing.

Alterations in perinatal conditions (such as preterm birth) is linked to adult health and disease, in particular, the cardiovascular system. Neddylation, a novel posttranslational modification through which the ubiquitin-like protein NEDD8 is conjugated to protein substrates, has emerged as an important mechanism regulating embryonic cardiac chamber maturation. However, the importance of neddylation in postpartum cardiac development has not been investigated. Here, we aimed to determine whether transient, postnatal inhibition of neddylation has immediate and prolonged impact on the structure and function of the neonatal and adult hearts. Sprague-Dawley pups were given three intraperitoneal injections of MLN4924 (MLN), a specific neddylation inhibitor, at postnatal days (P)1, 3, and 5. Cardiac structure and function were temporally assessed during aging and after 2 wk of isoproterenol (ISO) infusion in adulthood. MLN treatment resulted in modest reduction of neddylated proteins in neonatal hearts. The MLN-treated rats developed cardiac hypertrophy and dysfunction by P7, which was accompanied by significantly reduced cardiomyocyte proliferation. At 3 mo of age, cardiac contractile function was restored in MLN-treated rats, but MLN-treated hearts displayed hypertrophic phenotype. Whereas ISO infusion triggered compensatory cardiac hypertrophy without impairing cardiac contractility in the control rats, the MLN-treated rats displayed a similar degree of hypertrophy, which quickly progressed to decompensation with ventricular wall thinning, chamber dilatation, and reduced ejection fraction as well as exacerbated pathological cardiac remodeling. Our findings suggest that neddylation is required for postnatal cardiac development and that perturbation of neddylation during development predisposes adult hearts to cardiac failure under stress conditions. NEW & NOTEWORTHY Our study demonstrates that perinatal perturbation of neddylation induces cardiomyopathy, impairs postnatal cardiac development, and increases susceptibility to catecholamine-induced cardiac dysfunction. The results reveal a previously unappreciated role of neddylation in postnatal cardiac maturation and call for close monitoring for the potential cardiotoxicity of MLN4924 (pevonedistat) and other agents that modify neddylation, especially in pregnant women and preadolescents.

Genome editing technology based on the clustered regularly interspaced short palindromic repeats/Cas system is an important achievement of molecular biology. Nevertheless, public concerns regarding genetically modified organisms and regulatory restrictions have limited the use of this technology. Cell-penetrating peptides (CPPs) are protein transduction domains, usually less than dozens of amino acids, which have the ability to take cargo and penetrate the cell membrane of recipient cells. CPPs have only minor cytotoxicity and are ideal transfection tools for DNA-free transfection and genome editing in plants. In this review, we discuss the classifications and translocation mechanisms of CPPs, as well as the brief history of CPPs mediated DNA-free genome editing

Background: Defects in protein homeostasis are sufficient to provoke cardiac remodeling and dysfunction. Although posttranslational modifications by ubiquitin and ubiquitin-like proteins are emerging as an important regulatory mechanism of protein function, the role of Ufm1 (ubiquitin-fold modifier 1)—a novel ubiquitin-like protein—has not been explored in either the normal or stressed heart. Methods and Results: Western blotting revealed that Ufl1 (Ufm1-specific E3 ligase 1)—an enzyme essential for Ufm1 modification—was increased in hypertrophic mouse hearts but reduced in the failing hearts of patients with dilated cardiomyopathy. To determine the functional role of Ufl1 in the heart, we generated a cardiac-specific knockout mouse and showed that Ufl1-deficient mice developed age-dependent cardiomyopathy and heart failure, as indicated by elevated cardiac fetal gene expression, increased fibrosis, and impaired cardiac contractility. When challenged with pressure overload, Ufl1-deficient hearts exhibited remarkably greater hypertrophy, exacerbated fibrosis, and worsened cardiac contractility compared with control counterparts. Transcriptome analysis identified that genes associated with the endoplasmic reticulum (ER) function were dysregulated in Ufl1-deficient hearts. Biochemical analysis revealed that excessive ER stress preceded and deteriorated along with the development of cardiomyopathy in Ufl1-deficient hearts. Mechanistically, Ufl1 depletion impaired (PKR-like ER-resident kinase) signaling and aggravated cardiomyocyte cell death after ER stress. Administration of the chemical ER chaperone tauroursodeoxycholic acid to Ufl1-deficient mice alleviated ER stress and attenuated pressure overload-induced cardiac dysfunction. Conclusions: Our results advance a novel concept that the Ufm1 system is essential for cardiac homeostasis through regulation of ER function and that upregulation of myocardial Ufl1 could be protective against heart failure.

MicroRNAs (miRNAs) have been shown to play important roles in plant development, growth and stress response. Sweet sorghum [Sorghum bicolor (L.) Moench] is an important source of bioenergy due to the high sugar content in its stems. However, it is not clear how the miRNA is involved in sugar accumulation in sorghum stems. In order to identify the miRNAs in the stems and the leaves of sweet sorghum, we extracted RNAs of the stems and leaves of sweet sorghum (Rio) and grain sorghum (BTx623) at the heading and dough stages for high-throughput sequencing. A total of 179279048 reads were obtained from Illumina-based sequencing. Further analysis identified nine known miRNAs and twelve novel miRNAs that showed significantly and specifically differentially expressed in the stems of sweet sorghum. The target genes of the differentially expressed novel miRNAs include the transcription factor, glucosyltransferase, protein kinase, cytochrome P450, transporters etc. GO enrichment analysis showed that the predicted targets of these differentially expressed miRNAs participated in diverse physiological and metabolic processes. We performed RT-qRCR analysis on these miRNAs across eight different libraries to validate the miRNAs. Finally, we screened stem-specifically expressed novel miRNA and a leaf-specifically expressed novel miRNA in sweet sorghum comparing with grain sorghum. Our results provide a basis for further investigation of the potential role of these individual miRNAs in sugar accumulation.

Protein modifications by ubiquitin and ubiquitin-like proteins are emerging as an important regulatory mechanism of protein function and involved in various cellular processes. Ufm1 (ubiquitin-fold modifier 1) is a novel ubiquitin-like protein that modifies protein targets in a UBA5 (E1) - Ufc1 (E2) - Ufl1 (E3) dependent manner. While defects in ubiquitin- and SUMO-modification have been shown to provoke cardiac remodeling and dysfunction, the importance of Ufm1 modification has not been explored in the normal and stressed heart. Western blotting revealed that Ufm1 specific ligase 1 (Ufl1), an enzyme essential for Ufm1 modification, was increased in hypertrophic mouse hearts but reduced in the failing hearts of patients with dilated cardiomyopathy. To determine the functional role of Ufl1 in the heart, we generated a cardiac-specific knockout mouse and showed that Ufl1-deficient mice developed age-dependent cardiomyopathy and heart failure, as indicated by elevated cardiac fetal gene expression, increased fibrosis and impaired cardiac contractility. When challenged with pressure overload, Ufl1-deficient hearts exhibited remarkably greater hypertrophy, exacerbated fibrosis and worsened cardiac contractility compared with control counterparts. Transcriptome analysis identified that genes associated with the endoplasmic reticulum (ER) function were dysregulated in Ufl1-deficient hearts. Biochemical analysis revealed that excessive ER stress preceded and deteriorated along with the development of cardiomyopathy in Ufl1-deficient hearts. Mechanistically, Ufl1 depletion impaired PERK signaling and aggravated cardiomyocyte cell death following ER stress. Administration of the chemical ER chaperone tauroursodeoxycholic acid to Ufl1-deficient mice alleviated ER stress and attenuated pressure overload-induced cardiac dysfunction. Our results advance a novel concept that the Ufm1 system is essential for cardiac homeostasis through regulation of ER function and that upregulation of myocardial Ufl1 could be protective against heart failure.

Rationale: Cardiac development is orchestrated by a number of growth factors, transcription factors and epigenetic regulators, perturbation of which can lead to congenital heart diseases and cardiomyopathies. However, the role of novel ubiquitin-like protein modifiers, such as NEDD8 (neural precursor cells expressed developmentally downregulated 8), in cardiac development is unknown. Objectives: The objective of this study was to determine the significance of NEDD8 modification (neddylation) during perinatal cardiac development. Methods and Results: Neddylated proteins and NEDD8 enzymes were highly abundant in fetal and neonatal hearts but downregulated in adult hearts. We employed an αMHC Cre transgene to delete NAE1, a subunit of the NEDD8 E1 enzyme, in the perinatal mouse heart. Cardiac-specific deletion of NAE1 (NAE1 CKO ) significantly decreased neddylated proteins in the heart. The NAE1 CKO mice displayed cardiac hypoplasia, ventricular non-compaction and heart failure during late gestation, which became more pronounced by postnatal day 1 and led to perinatal lethality. Mechanistically, genetic deletion or pharmacological inhibition of NAE1 resulted in accumulation of Hippo kinases Mst1 and LATS1/2, which in turn phosphorylated and inactivated YAP, a transcription cofactor necessary for cardiomyocyte proliferation, leading to dysregulation of a number of cell cycle-regulatory genes and blockade of cardiomyocyte proliferation in vivo and in vitro . Reactivation of YAP signaling by overexpression of a constitutively-active YAP mutant (YAP 5SA ), but not its wild-type counterpart, overcame the blockade of cardiomyocyte proliferation induced by inhibition of NAE1. Conclusions: Our findings establish the importance of neddylation in the heart, more specifically, in ventricular chamber maturation, and identify neddylation as a novel regulator of Hippo-YAP signaling to promote cardiomyocyte proliferation.

Summary DNA damage response (DDR) and the centrosome cycle are two of the most critical processes for maintaining a stable genome in animals. Sporadic evidence suggests a connection between these two processes. Here, we report our findings that six Fanconi Anemia (FA) proteins, including FancI and FancJ, localize to the centrosome. Intriguingly, we found that the localization of FancJ to the mother centrosome is stimulated by a DNA interstrand crosslinker, Mitomycin C (MMC). We further show that, in addition to its role in interstrand crosslinking (ICL) repair, FancJ also regulates the normal centrosome cycle as well as ICL induced centrosome amplification by activating the polo-like kinase 1 (PLK1). We have uncovered a novel function of FancJ in centrosome biogenesis and established centrosome amplification as an integral part of the ICL response.

Osmopriming with PEG has potential to improve seed germination, seedling emergence, and establishment, especially under stress conditions. This research investigated germination performance, seedling establishment, and effects of osmopriming with PEG on physiology in sorghum seedlings and their association with post-priming stress tolerance under various soil moisture stress conditions. Results showed that seed priming increased the environmental range suitable for sorghum germination and has potential to provide more uniform and synchronous emergence. Physiologically, seed priming strengthened the antioxidant activities of APX, CAT, POD, and SOD, as well as compatible solutes including free amino acid, reducing sugar, proline, soluble sugar, and soluble protein contents. As a result, seed priming reduced lipid peroxidation and stabilized the cell membrane, resulting in increased stress tolerance under drought or excessive soil moisture environments. Overall, results suggested that seed priming with PEG was effective in improving seed germination and seedling establishment of sorghum under adverse soil moisture conditions. Osmopriming effectively strengthened the antioxidant system and increased osmotic adjustment, likely resulting in increased stress tolerance.

DNA damage response (DDR) and the centrosome cycle are 2 of the most critical cellular processes affecting the genome stability in animal cells. Yet the cross-talks between DDR and the centrosome are poorly understood. Here we showed that deficiency of the breast cancer 1, early onset gene (BRCA1) induces centrosome amplification in non-stressed cells as previously reported while attenuating DNA damage-induced centrosome amplification (DDICA) in cells experiencing prolonged genotoxic stress. Mechanistically, the function of BRCA1 in promoting DDICA is through binding and recruiting polo-like kinase 1 (PLK1) to the centrosome. In a recent study, we showed that FancJ also suppresses centrosome amplification in non-stressed cells while promoting DDICA in both hydroxyurea and mitomycin C treated cells. FancJ is a key component of the BRCA1 B-complex. Here, we further demonstrated that, in coordination with BRCA1, FancJ promotes DDICA by recruiting both BRCA1 and PLK1 to the centrosome in the DNA damaged cells. Thus, we have uncovered a novel role of BRCA1 and FancJ in the regulation of DDICA. Dysregulation of DDR or centrosome cycle leads to aneuploidy, which is frequently seen in both solid and hematological cancers. BRCA1 and FancJ are known tumor suppressors and have well-recognized functions in DNA damage checkpoint and DNA repair. Together with our recent findings, we demonstrated here that BRCA1 and FancJ also play an important role in centrosome cycle especially in DDICA. DDICA is thought to be an alternative fail-safe mechanism to prevent cells experiencing severe DNA damage from becoming carcinogenic. Therefore, BRCA1 and FancJ are potential liaisons linking early DDR with the DDICA. We propose that together with their functions in DDR, the role of BRCA1 and FancJ in the activation of DDICA is also crucial for their tumor suppression functions in vivo.

In response to DNA damage or replication stress, proliferating cells are arrested at different cell cycle stages for DNA repair by downregulating the activity of both the cyclin-dependent kinases (CDKs) and other important cell cycle kinases, including Polo-like kinase 1 (PLK1) . The signaling pathway to inhibit CDKs is relatively well understood, and breast cancer gene 1 (BRCA1) and other DNA damage response (DDR) factors play a key role in this process. However, the DNA damage-induced inhibition of PLK1 is still largely a mystery. Here we show that DNA damage and replication stress stimulate the association between BRCA1 and PLK1. Most importantly, we demonstrate that BRCA1 downregulates the kinase activity of PLK1 by modulating the dynamic interactions of Aurora A, hBora, and PLK1. Together with previous findings, we propose that in response to replication stress and DNA damage, BRCA1 plays a critical role in downregulating the kinase activity of both CDKs and PLK1.

Breast cancer gene 1 ( BRCA1 ) deficient cells not only are hypersensitive to double-strand breaks but also are hypersensitive to UV irradiation and other agents that cause replication blockade; however, the molecular mechanisms behind these latter sensitivities are largely unknown. Here, we report that BRCA1 promotes cell survival by directly regulating the DNA damage tolerance pathway in response to agents that create cross-links in DNA. We show that BRCA1 not only promotes efficient mono- and polyubiquitination of proliferating cell nuclear antigen (PCNA) by regulating the recruitment of replication protein A, Rad18, and helicase-like transcription factor to chromatin but also directly recruits translesion polymerases, such as Polymerase eta and Rev1, to the lesions through protein–protein interactions. Our data suggest that BRCA1 plays a critical role in promoting translesion DNA synthesis as well as DNA template switching.

The productivity of sorghum is mainly determined by agronomically important traits. The genetic bases of these traits have historically been dissected and analysed through quantitative trait locus (QTL) mapping based on linkage maps with low-throughput molecular markers, which is one of the factors that hinder precise and complete information about the numbers and locations of the genes or QTLs controlling the traits. In this study, an ultra-high-density linkage map based on high-quality single nucleotide polymorphisms (SNPs) generated from low-coverage sequences (~0.07 genome sequence) in a sorghum recombinant inbred line (RIL) population was constructed through new sequencing technology. This map consisted of 3418 bin markers and spanned 1591.4 cM of genome size with an average distance of 0.5 cM between adjacent bins. QTL analysis was performed and a total of 57 major QTLs were detected for eight agronomically important traits under two contrasting photoperiods. The phenotypic variation explained by individual QTLs varied from 3.40% to 33.82%. The high accuracy and quality of this map was evidenced by the finding that genes underlying two cloned QTLs, Dw3 for plant height (chromosome 7) and Ma1 for flowering time (chromosome 6), were localized to the correct genomic regions. The close associations between two genomic regions on chromosomes 6 and 7 with multiple traits suggested the existence of pleiotropy or tight linkage. Several major QTLs for heading date, plant height, numbers of nodes, stem diameter, panicle neck length, and flag leaf width were detected consistently under both photoperiods, providing useful information for understanding the genetic mechanisms of the agronomically important traits responsible for the change of photoperiod.

The present study was to characterize a procyanidin-rich extract (PARE) from sorghum ( Sorghum bicolor (L.) Moench) bran and assess its biological activities. The procyanidin oligomers were separated and identified by normal-phase HPLC equipped with fluorescence (FLD) and mass spectrometry (MS) detectors. In addition, the effects of PARE on oxidative stress in mice induced by D-galactose as well as tumor inhibition in C57BL/6J mice bearing Lewis lung cancer were investigated. Administration of D-galactose significantly (p < 0.05) lowered the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). This was accompanied by a significant (p < 0.05) increase in malondialdehyde (MDA) levels in both liver and serum. Administration of PARE (150 mg/kg) significantly (p < 0.05) reversed the d-galactose-induced oxidative stress by enhancing the activities of antioxidant enzymes. Furthermore, PARE administration inhibited tumor growth and metastasis formation by suppressing vascular endothelial growth factor (VEGF) production. The results suggested that PARE had antioxidant and antitumor activities.