Structural and functional investigation of GajB protein in Gabija anti-phage defense.

Bacteriophages (phages) are viruses that infect bacteria and archaea. To fend off invading phages, the hosts have evolved a variety of anti-phage defense mechanisms. Gabija is one of the most abundant prokaryotic antiviral systems and consists of two proteins, GajA and GajB. GajA has been characterized experimentally as a sequence-specific DNA endonuclease. Although GajB was previously predicted to be a UvrD-like helicase, its function is unclear. Here, we report the results of structural and functional analyses of GajB. The crystal structure of GajB revealed a UvrD-like domain architecture, including two RecA-like core and two accessory subdomains. However, local structural elements that are important for the helicase function of UvrD are not conserved in GajB. In functional assays, GajB did not unwind or bind various types of DNA substrates. We demonstrated that GajB interacts with GajA to form a heterooctameric Gabija complex, but GajB did not exhibit helicase activity when bound to GajA. These results advance our understanding of the molecular mechanism underlying Gabija anti-phage defense and highlight the role of GajB as a component of a multi-subunit antiviral complex in bacteria.

The structure of AcrIE4-F7 reveals a common strategy for dual CRISPR inhibition by targeting PAM recognition sites.

Bacteria and archaea use the CRISPR-Cas system to fend off invasions of bacteriophages and foreign plasmids. In response, bacteriophages encode anti-CRISPR (Acr) proteins that potently inhibit host Cas proteins to suppress CRISPR-mediated immunity. AcrIE4-F7, which was isolated from Pseudomonas citronellolis, is a fused form of AcrIE4 and AcrIF7 that inhibits both type I-E and type I-F CRISPR-Cas systems. Here, we determined the structure of AcrIE4-F7 and identified its Cas target proteins. The N-terminal AcrIE4 domain adopts a novel α-helical fold that targets the PAM interaction site of the type I-E Cas8e subunit. The C-terminal AcrIF7 domain exhibits an αß fold like native AcrIF7, which disables target DNA recognition by the PAM interaction site in the type I-F Cas8f subunit. The two Acr domains are connected by a flexible linker that allows prompt docking onto their cognate Cas8 targets. Conserved negative charges in each Acr domain are required for interaction with their Cas8 targets. Our results illustrate a common mechanism by which AcrIE4-F7 inhibits divergent CRISPR-Cas types.

Asp149 and Asp152 in chicken and human ANP32A play an essential role in the interaction with influenza viral polymerase.

The acidic nuclear phosphoprotein 32 family member A (ANP32A) is a cellular host factor that determines the host tropism of the viral polymerase (vPol) of avian influenza viruses (AIVs). Compared with human ANP32A (hANP32A), chicken ANP32A contains an additional 33 amino acid residues (176-208) duplicated from amino acid residues 149-175 (27 residues), suggesting that these residues could be involved in increasing vPol activity by strengthening interactions between ANP32A and vPol. However, the molecular interactions and functional roles of the 27 residues within hANP32A during AIV vPol activity remain unclear. Here, we examined the functional role of 27 residues of hANP32A based on comparisons with other human (h) ANP32 family members. It was notable that unlike hANP32A and hANP32B, hANP32C could not support vPol activity or replication of AIVs, despite the fact that hANP32C shares a higher sequence identity with hANP32A than hANP32B. Pairwise comparison between hANP32A and hANP32C revealed that Asp149 (D149) and Asp152 (D152) are involved in hydrogen bonding and electrostatic interactions, respectively, which support vPol activity. Mutation of these residues reduced the interaction between hANP32A and vPol. Finally, we demonstrated that precise substitution of the identified residues within chicken ANP32A via homology-directed repair using the CRISPR/Cas9 system resulted in a marked reduction of viral replication in chicken cells. These results increase our understanding of ANP32A function and may facilitate the development of AIV-resistant chickens via precise modification of residues within ANP32A.

Structural and mechanistic insights into the CRISPR inhibition of AcrIF7.

The CRISPR-Cas system provides adaptive immunity for bacteria and archaea to combat invading phages and plasmids. Phages evolved anti-CRISPR (Acr) proteins to neutralize the host CRISPR-Cas immune system as a counter-defense mechanism. AcrIF7 in Pseudomonas aeruginosa prophages strongly inhibits the type I-F CRISPR-Cas system. Here, we determined the solution structure of AcrIF7 and identified its target, Cas8f of the Csy complex. AcrIF7 adopts a novel ß1ß2α1α2ß3 fold and interacts with the target DNA binding site of Cas8f. Notably, AcrIF7 competes with AcrIF2 for the same binding interface on Cas8f without common structural motifs. AcrIF7 binding to Cas8f is driven mainly by electrostatic interactions that require position-specific surface charges. Our findings suggest that Acrs of divergent origin may have acquired specificity to a common target through convergent evolution of their surface charge configurations.

Intrinsic disorder is essential for Cas9 inhibition of anti-CRISPR AcrIIA5.

Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins provide adaptive immunity to prokaryotes against invading phages and plasmids. As a countermeasure, phages have evolved anti-CRISPR (Acr) proteins that neutralize the CRISPR immunity. AcrIIA5, isolated from a virulent phage of Streptococcus thermophilus, strongly inhibits diverse Cas9 homologs, but the molecular mechanism underlying the Cas9 inhibition remains unknown. Here, we report the solution structure of AcrIIA5, which features a novel α/ß fold connected to an N-terminal intrinsically disordered region (IDR). Remarkably, truncation of the N-terminal IDR abrogates the inhibitory activity against Cas9, revealing that the IDR is essential for Cas9 inhibition by AcrIIA5. Progressive truncations and mutations of the IDR illustrate that the disordered region not only modulates the association between AcrIIA5 and Cas9-sgRNA, but also alters the catalytic efficiency of the inhibitory complex. The length of IDR is critical for the Cas9-sgRNA recognition by AcrIIA5, whereas the charge content of IDR dictates the inhibitory activity. Conformational plasticity of IDR may be linked to the broad-spectrum inhibition of Cas9 homologs by AcrIIA5. Identification of the IDR as the main determinant for Cas9 inhibition expands the inventory of phage anti-CRISPR mechanisms.

Crystal structure of an anti-CRISPR protein, AcrIIA1.

Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins provide bacteria with RNA-based adaptive immunity against phage infection. To counteract this defense mechanism, phages evolved anti-CRISPR (Acr) proteins that inactivate the CRISPR-Cas systems. AcrIIA1, encoded by Listeria monocytogenes prophages, is the most prevalent among the Acr proteins targeting type II-A CRISPR-Cas systems and has been used as a marker to identify other Acr proteins. Here, we report the crystal structure of AcrIIA1 and its RNA-binding affinity. AcrIIA1 forms a dimer with a novel two helical-domain architecture. The N-terminal domain of AcrIIA1 exhibits a helix-turn-helix motif similar to transcriptional factors. When overexpressed in Escherichia coli, AcrIIA1 associates with RNAs, suggesting that AcrIIA1 functions via nucleic acid recognition. Taken together, the unique structural and functional features of AcrIIA1 suggest its distinct mode of Acr activity, expanding the diversity of the inhibitory mechanisms employed by Acr proteins.

Changes in Characteristics of Patients with Liver Cirrhosis Visiting a Tertiary Hospital over 15 Years: a Retrospective Multi-Center Study in Korea.

BACKGROUND: Liver cirrhosis has become a heavy burden not only for patients, but also for our society. However, little is known about the recent changes in clinical outcomes and characteristics of patients with cirrhosis-related complications in Korea. Therefore, we aimed to evaluate changes in characteristics of patients with liver cirrhosis in Daegu-Gyeongbuk province in Korea over the past 15 years. METHODS: We retrospectively reviewed the medical records of 15,716 liver cirrhotic patients from 5 university hospitals in Daegu-Gyeongbuk province from 2000 to 2014. The Korean Standard Classification of Diseases-6 code associated with cirrhosis was investigated through medical records and classified according to the year of first visit. RESULTS: A total of 15,716 patients was diagnosed with cirrhosis. A number of patients newly diagnosed with cirrhosis has decreased each year. In 2000, patients were most likely to be diagnosed with hepatitis B virus (HBV) cirrhosis, followed by alcoholic cirrhosis. There was a significant decrease in HBV (P < 0.001), but alcohol, hepatitis C virus (HCV), and non-alcoholic fatty liver disease (NAFLD) showed a significant increase during the study period (alcohol, P = 0.036; HCV, P = 0.001; NAFLD, P = 0.001). At the time of initial diagnosis, the ratio of Child-Turcotte-Pugh (CTP) class A gradually increased from 23.1% to 32.9% (P < 0.001). The most common cause of liver-related hospitalization in 2000 was hepatocellular carcinoma (HCC) (25.5%); in 2014, gastrointestinal bleeding with esophageal and gastric varices (21.4%) was the most common cause. Cases of hospitalization with liver-related complication represented 76.4% of all cases in 2000 but 70.9% in 2014. Incidence rate of HCC has recently increased. In addition, HCC-free survival was significantly lower in CTP class A than in classes B and C. Finally, there was significant difference in HCC occurrence according to causes (P < 0.001). HBV and HCV cirrhosis had lower HCC-free survival than alcoholic and NAFLD cirrhosis. CONCLUSION: In recent years, the overall number of cirrhosis patients has decreased. This study confirmed the recent trend in decrease of cirrhosis, especially of cirrhosis due to HBV, and the increase of HCV, alcoholic and NAFLD cirrhosis. Targeted screening for at-risk patients will facilitate early detection of liver diseases allowing effective intervention and may have decreased the development of cirrhosis and its complications.

A Coil-to-Helix Transition Serves as a Binding Motif for hSNF5 and BAF155 Interaction.

Human SNF5 and BAF155 constitute the core subunit of multi-protein SWI/SNF chromatin-remodeling complexes that are required for ATP-dependent nucleosome mobility and transcriptional control. Human SNF5 (hSNF5) utilizes its repeat 1 (RPT1) domain to associate with the SWIRM domain of BAF155. Here, we employed X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and various biophysical methods in order to investigate the detailed binding mechanism between hSNF5 and BAF155. Multi-angle light scattering data clearly indicate that hSNF5171-258 and BAF155SWIRM are both monomeric in solution and they form a heterodimer. NMR data and crystal structure of the hSNF5171-258/BAF155SWIRM complex further reveal a unique binding interface, which involves a coil-to-helix transition upon protein binding. The newly formed αN helix of hSNF5171-258 interacts with the ß2-α1 loop of hSNF5 via hydrogen bonds and it also displays a hydrophobic interaction with BAF155SWIRM. Therefore, the N-terminal region of hSNF5171-258 plays an important role in tumorigenesis and our data will provide a structural clue for the pathogenesis of Rhabdoid tumors and malignant melanomas that originate from mutations in the N-terminal loop region of hSNF5.

CRISPR RNA and anti-CRISPR protein binding to the Xanthomonas albilineans Csy1-Csy2 heterodimer in the type I-F CRISPR-Cas system.

Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins provide microbial adaptive immunity against bacteriophages. In type I-F CRISPR-Cas systems, multiple Cas proteins (Csy1-4) compose a surveillance complex (Csy complex) with CRISPR RNA (crRNA) for target recognition. Here, we report the biochemical characterization of the Csy1-Csy2 subcomplex from Xanthomonas albilineans, including the analysis of its interaction with crRNA and AcrF2, an anti-CRISPR (Acr) protein from a phage that infects Pseudomonas aeruginosa The X. albilineans Csy1 and Csy2 proteins (XaCsy1 and XaCsy2, respectively) formed a stable heterodimeric complex that specifically bound the 8-nucleotide (nt) 5'-handle of the crRNA. In contrast, the XaCsy1-XaCsy2 heterodimer exhibited reduced affinity for the 28-nt X. albilineans CRISPR repeat RNA containing the 5'-handle sequence. Chromatographic and calorimetric analyses revealed tight binding between the Acr protein from the P. aeruginosa phage and the heterodimeric subunit of the X. albilineans Csy complex, suggesting that AcrF2 recognizes conserved features of Csy1-Csy2 heterodimers. We found that neither XaCsy1 nor XaCsy2 alone forms a stable complex with AcrF2 and the 5'-handle RNA, indicating that XaCsy1-XaCsy2 heterodimerization is required for binding them. We also solved the crystal structure of AcrF2 to a resolution of 1.34 Å, enabling a more detailed structural analysis of the residues involved in the interactions with the Csy1-Csy2 heterodimer. Our results provide information about the order of events during the formation of the multisubunit crRNA-guided surveillance complex and suggest that the Acr protein inactivating type I-F CRISPR-Cas systems has broad specificity.

Chicken NANOG self-associates via a novel folding-upon-binding mechanism.

NANOG plays a pivotal role in pluripotency acquisition and lineage specification in higher vertebrates, and its expression is restricted to primordial germ cells (PGCs) during early embryonic development. Mammalian NANOG self-associates via conserved tryptophan-repeat motifs in the C-terminal domain (CTD) to maintain pluripotency. Avian NANOG, however, lacks the conserved motifs, and the molecular mechanism underlying the biologic function is not clearly understood. Here, using spectroscopic and biochemical methods as well as cell-based assays, we report that chicken NANOG (cNANOG) oligomerizes through its CTD via a novel folding-upon-binding mechanism. The CTD of cNANOG is disordered as a monomer and associates into an α-helical multimer driven by intermolecular hydrophobic interactions. Mutation of key aromatic residues in the CTD abrogates the self-association, leading to a loss of the proliferation of chicken PGCs and blastoderm cells. Our results demonstrate that the CTD of cNANOG belongs to a novel IDP that switches into a helical oligomer via self-association, enabling the maintenance of PGCs and blastoderm cells.-Choi, H. J., Kim, I., Lee, H. J., Park, Y. H., Suh, J.-Y., Han, J. Y. Chicken NANOG self-associates via a novel folding-upon-binding mechanism.

Device-Related Error in Patient-Controlled Analgesia: Analysis of 82,698 Patients in a Tertiary Hospital.

BACKGROUND: Patient-controlled analgesia (PCA) is one of the most popular and effective methods for managing postoperative pain. Various types of continuous infusion pumps are available for the safe and accurate administration of analgesic drugs. Here we report the causes and clinical outcomes of device-related errors in PCA. METHODS: Clinical records from January 1, 2011 to December 31, 2014 were collected by acute pain service team nurses in a 2715-bed tertiary hospital. Devices for all types of PCA, including intravenous PCA, epidural PCA, and nerve block PCA, were included for analysis. The following 4 types of infusion pumps were used during the study period: elastomeric balloon infusers, carbon dioxide-driven infusers, semielectronic disposable pumps, and electronic programmable pumps. We categorized PCA device-related errors based on the error mechanism and clinical features. RESULTS: Among 82,698 surgical patients using PCA, 610 cases (0.74%) were reported as human error, and 155 cases (0.19%) of device-related errors were noted during the 4-year study period. The most common type of device-related error was underflow, which was observed in 47 cases (30.3%). The electronic programmable pump exhibited the high incidence of errors in PCA (70 of 15,052 patients; 0.47%; 95% confidence interval, 0.36-0.59) among the 4 types of devices, and 96 of 152 (63%) patients experienced some type of adverse outcome, ranging from minor symptoms to respiratory arrest. CONCLUSIONS: The incidence of PCA device-related errors was <0.2% and significantly differed according to the infusion pump type. A total of 63% of patients with PCA device-related errors suffered from adverse clinical outcomes, with no mortality. Recent technological advances may contribute to reducing the incidence and severity of PCA errors. Nonetheless, the results of this study can be used to improve patient safety and ensure quality care.

Peptide switch is essential for Sirt1 deacetylase activity.

In mammals, the Sirtuins are composed of seven Sir2 orthologs (Sirt1-7) with a conserved deacetylase core that utilizes NAD(+) as a cofactor. Interestingly, the deacetylase core of Sirt1 by itself has no catalytic activity. We found within the C-terminal domain a 25 aa sequence that is essential for Sirt1 activity (ESA). Our results indicate that the ESA region interacts with and functions as an "on switch" for the deacetylase core. The endogenous Sirt1 inhibitor DBC1, which also binds to the deacetylase core, competes with and inhibits the ESA region from interacting with the deacetylase core. We discovered an ESA mutant peptide that can bind to the deacetylase core and inhibit Sirt1 in trans. By using this mutant peptide, we were able to inhibit Sirt1 activity and to increase the chemosensitivity of androgen-refractory prostate cancer cells. Therefore, the ESA region is a potential target for development of therapies to regulate Sirt1.

Anti-inflammatory effect of astaxanthin in phthalic anhydride-induced atopic dermatitis animal model.

In this study, we investigated anti-dermatitic effects of astaxanthin (AST) in phthalic anhydride (PA)-induced atopic dermatitis (AD) animal model as well as in vitro model. AD-like lesion was induced by the topical application of 5% PA to the dorsal skin or ear of Hos:HR-1 mouse. After AD induction, 100 µL of 1 mg/mL and 2 mg/mL of AST (10 µg or 20 µg/cm2 ) was spread on the dorsum of ear or back skin three times a week for four weeks. We evaluated dermatitis severity, histopathological changes and changes in protein expression by Western blotting for inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and nuclear factor-κB (NF-κB) activity. We also measured tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-6 (IL-6) and immunoglobulin E (IgE) concentration in the blood of AD mice by enzyme-linked immunosorbent assay (ELISA). AST treatment attenuated the development of PA-induced AD. Histological analysis showed that AST inhibited hyperkeratosis, mast cells and infiltration of inflammatory cells. AST treatment inhibited expression of iNOS and COX-2, and NF-κB activity as well as release of TNF-α, IL-1ß, IL-6 and IgE. In addition, AST (5, 10 and 20 µM) potently inhibited lipopolysaccharide (LPS) (1 µg/mL)-induced nitric oxide (NO) production, expression of iNOS and COX-2 and NF-κB DNA binding activities in RAW 264.7 macrophage cells. Our data demonstrated that AST could be a promising agent for AD by inhibition of NF-κB signalling.

Chronic Hepatitis B Infection Is Significantly Associated with Chronic Kidney Disease: a Population-based, Matched Case-control Study.

BACKGROUND: Hepatitis B virus (HBV) infection leads to hepatic and extrahepatic manifestations including chronic kidney disease (CKD). However, the association between HBV and CKD is not clear. This study investigated the association between chronic HBV infection and CKD in a nationwide multicenter study. METHODS: A total of 265,086 subjects who underwent health-check examinations in 33 hospitals from January 2015 to December 2015 were enrolled. HBV surface antigen (HBsAg) positive cases (n = 10,048), and age- and gender-matched HBsAg negative controls (n = 40,192) were identified. CKD was defined as a glomerular filtration rate (GFR) < 60 mL/min/1.73 m2 or proteinuria as at least grade 2+ of urine protein. RESULTS: HBsAg positive cases showed a significantly higher prevalence of GFR < 60 mL/min/1.73 m2 (3.3%), and proteinuria (18.9%) than that of the controls (2.6%, P < 0.001, and 14.1%, P < 0.001, respectively). In the multivariate analysis, HBsAg positivity was an independent factor associated with GFR < 60 mL/min/1.73 m2 along with age, blood levels of albumin, bilirubin, anemia, and hemoglobin A1c (HbA1c). Likewise, HBsAg positivity was an independent factor for proteinuria along with age, male, blood levels of bilirubin, protein, albumin, and HbA1c. A subgroup analysis showed that HBsAg positive men but not women had a significantly increased risk for GFR < 60 mL/min/1.73 m2. CONCLUSION: Chronic HBV infection was significantly associated with a GFR < 60 mL/min/1.73 m2 and proteinuria (≥ 2+). Therefore, clinical concern about CKD in chronic HBV infected patients, especially in male, is warranted.

Exosome Cofactors Connect Transcription Termination to RNA Processing by Guiding Terminated Transcripts to the Appropriate Exonuclease within the Nuclear Exosome.

The yeast Nrd1 interacts with the C-terminal domain (CTD) of RNA polymerase II (RNApII) through its CTD-interacting domain (CID) and also associates with the nuclear exosome, thereby acting as both a transcription termination and RNA processing factor. Previously, we found that the Nrd1 CID is required to recruit the nuclear exosome to the Nrd1 complex, but it was not clear which exosome subunits were contacted. Here, we show that two nuclear exosome cofactors, Mpp6 and Trf4, directly and competitively interact with the Nrd1 CID and differentially regulate the association of Nrd1 with two catalytic subunits of the exosome. Importantly, Mpp6 promotes the processing of Nrd1-terminated transcripts preferentially by Dis3, whereas Trf4 leads to Rrp6-dependent processing. This suggests that Mpp6 and Trf4 may play a role in choosing a particular RNA processing route for Nrd1-terminated transcripts within the exosome by guiding the transcripts to the appropriate exonuclease.

Biophysical characterization of Ca2+-binding of S100A5 and Ca2+-induced interaction with RAGE.

S100A5 is a calcium-binding protein of S100 family, which represents a major ligand to the receptor for advanced glycation end product (RAGE), a pattern recognition receptor engaged in diverse pathological processes. Here we have characterized calcium binding of S100A5 and the complex formation between S100A5 and RAGE using calorimetry and NMR spectroscopy. S100A5 binds to calcium ions in a sequential manner with the equilibrium dissociation constants (KD) of 1.3 µM and 3.5 µM, which corresponds to the calcium-binding at the C-terminal and N-terminal EF-hands. Upon calcium binding, S100A5 interacts with the V domain of RAGE (RAGE-v) to form a heterotrimer (KD ∼5.9 µM) that is distinct among the S100 family proteins. Chemical shift perturbation data from NMR titration experiments indicates that S100A5 employs the periphery of the dimer interface to interact with RAGE-v. Distinct binding mode and stoichiometry of RAGE against different S100 family proteins could be important to modulate diverse RAGE signaling.

New Optimal Needle Entry Angle for Cervical Transforaminal Epidural Steroid Injections: A Retrospective Study.

Objective: A cervical epidural steroid injection is one of the most commonly performed interventions to manage chronic neck pain and cervical radiculopathy. Despite its many severe complications, cervical transforaminal epidural steroid injection (CTFESI) is a clinically necessary modality for managing neck pain and cervical radiculopathy. We aimed in this study to find a safer optimal needle entry angle to decrease the chance of an accidental vertebral artery (VA) puncture even with a proper needle entry angle and to visualize the target of the needle tip. Methods: This retrospective study included 312 patients with neck pain or cervical radiculopathy who had undergone magnetic resonance imaging scans for diagnosis and treatment. The first line was drawn from the midpoint of the two articular pillars and passed through the exact midline of the spinous process. The second line was drawn parallel to the ventral lamina line (conventional transforaminal approach line, CTAL). The third line was drawn parallel to the ventral margin at the midpoint of the superior articular process's ventral border (new transforaminal approach line, NTAL). The angle of intersection between the midline and CTAL versus with NTAL were measured from both sides (right and left) at C5-6, C6-7, and C7-T1 levels. Also, the distance of CTAL and NTAL from VA were measured from both sides at each level. We examined whether the CTAL and NTAL would penetrate the ipsilateral VA, internal carotid artery (ICA), and internal jugular vein (IJV). Results: There were significant differences between CTAL and NTAL angles at all levels (P < 0.001). There were significant differences between the distance of CTAL and NTAL from VA at all levels (P < 0.001). There were also significant differences between the observed frequency of CTAL and NTAL that would penetrate the major ipsilateral vessel (VA, ICA, and IJV) on all levels and sides (P < 0.001~0.030). Conclusion: The angle of NTAL (approximately 70°) is safer than the angle of CTAL (approximately 50°) when considering vascular injuries to vessels, such as the VA, ICA, and IJV.

Structural basis for the auxin-induced transcriptional regulation by Aux/IAA17.

Auxin is the central hormone that regulates plant growth and organ development. Transcriptional regulation by auxin is mediated by the auxin response factor (ARF) and the repressor, AUX/IAA. Aux/IAA associates with ARF via domain III-IV for transcriptional repression that is reversed by auxin-induced Aux/IAA degradation. It has been known that Aux/IAA and ARF form homo- and hetero-oligomers for the transcriptional regulation, but what determines their association states is poorly understood. Here we report, to our knowledge, the first solution structure of domain III-IV of Aux/IAA17 (IAA17), and characterize molecular interactions underlying the homotypic and heterotypic oligomerization. The structure exhibits a compact ß-grasp fold with a highly dynamic insert helix that is unique in Aux/IAA family proteins. IAA17 associates to form a heterogeneous ensemble of front-to-back oligomers in a concentration-dependent manner. IAA17 and ARF5 associate to form homo- or hetero-oligomers using a common scaffold and binding interfaces, but their affinities vary significantly. The equilibrium dissociation constants (KD) for homo-oligomerization are 6.6 µM and 0.87 µM for IAA17 and ARF5, respectively, whereas hetero-oligomerization reveals a ∼ 10- to ∼ 100-fold greater affinity (KD = 73 nM). Thus, individual homo-oligomers of IAA17 and ARF5 spontaneously exchange their subunits to form alternating hetero-oligomers for transcriptional repression. Oligomerization is mainly driven by electrostatic interactions, so that charge complementarity at the interface determines the binding affinity. Variable binding affinity by surface charge modulation may effectively regulate the complex interaction network between Aux/IAA and ARF family proteins required for the transcriptional control of auxin-response genes.

The diarylheptanoid hirsutenone sensitizes chemoresistant ovarian cancer cells to cisplatin via modulation of apoptosis-inducing factor and X-linked inhibitor of apoptosis.

Cisplatin (CDDP) and its derivatives are considered first-line treatments for ovarian cancer (OVCA). However, despite initial results that often appear promising, in most cases patients will return with recurrent disease that fails to respond to further chemotherapy. We assayed a number of food phytochemicals with reported PI3K inhibitory ability to identify candidates that can influence CDDP treatment outcomes in chemoresistant OVCA cell lines. A direct comparison revealed that the diarylheptanoid hirsutenone from the tree bark of Alnus hirsuta var. sibirica was superior at inducing CDDP sensitivity in a number of chemoresistant cancer cell lines. Whereas hirsutenone treatment activated p53, its modest efficacy in p53-mutant and -null cell lines suggested the existence of a p53-independent mode of action. Further investigation revealed that hirsutenone causes CDDP-dependent apoptosis in chemoresistant cells by ubiquitin-proteasome-dependent X-linked inhibitor of apoptosis degradation and by enhancing the translocation of apoptosis-inducing factor from the mitochondria to the nucleus. This was found to be, at least in part, under the influence of upstream Akt activity, linking hirsutenone-dependent PI3K inhibition with downstream effects on apoptosis-inducing factor, X-linked inhibitor of apoptosis, and apoptosis. Our findings provide rationale for further investigation of the effects of hirsutenone on chemoresistant OVCA in clinical studies.

Treatment of chronic lumbosacral radicular pain using adjuvant pulsed radiofrequency: a randomized controlled study.

OBJECTIVES: The objective of this study was to determine the effects of combining pulsed radiofrequency (PRF) treatment and transforaminal epidural injection (TFEI) to treat patients with chronic refractory lumbar radicular pain caused by lumbar spinal stenosis. STUDY DESIGN: Randomized control trial. SETTINGS: Interventional pain management practice. METHOD: Sixty-two patients were assigned to the study groups (PRF group = 31; control group = 31). Under fluoroscopic guidance, the RF needle was positioned close to the lumbar dorsal root ganglion. The PRF group received 3 cycles of PRF treatment, and sensory stimulation without RF lesioning was applied to the control group. After PRF or sham lesioning, a local anesthetic with steroid was injected. The primary outcome of a successful response was defined as: 1) ≥50% or 4-point pain reduction in the numerical rating scale (NRS) without an increase in the Oswestry disability index (ODI) or medication quantification scale (MQS), or mean score <4 in the global perceived effect (GPE) scale; or 2) ≥30% or 2-point pain reduction in NRS with a simultaneous decrease in ODI, MQS, or ≥6 points in the GPE scale. RESULT: The number of patients with successful treatment results was higher in the PRF group at 2 months (P = 0.032) and 3 months (P = 0.018). No significant differences were observed in terms of the secondary outcome variables between the 2 groups. CONCLUSION: The TFEI provided significant short-term pain relief and PRF can be applied in conjunction with TFEI to achieve higher treatment efficacy compared with TFEI alone.