Phosphorylation-induced flexibility of proto-oncogenic Bcl3 regulates transcriptional activation by NF-κB p52 homodimer.

The overexpression of proto-oncogene Bcl3 is observed in various cancers. Bcl3 is extensively phosphorylated and associates with homodimers of NF-κB p50 and p52 to regulate transcription. Through cellular and biochemical assays, we observed that phospho-mimetic Glu substitution at Ser366 in addition to previously studied Ser33, 114 and 446 is necessary to switch Bcl3 from an IκB-like inhibitor to a transcriptional activator. To study interactive features of p52 and Bcl3, and phosphorylation- mediated changes in Bcl3 that regulate DNA-binding by p52, we performed HDX-MS of both Bcl3 and p52 within various complexes. Nature of interactions within Bcl3:(p52:p52) complex in presence and absence of DNA, differential flexibility of Bcl3, and allosteric changes in Bcl3 upon phospho-modifications revealed why a facile accommodation of DNA requires phosphorylation. The inhibitory nature of unphosphorylated Bcl3 on DNA binding by p52:p52 also relieved by a C-terminal deletion of Bcl3. Overall, this study revealed mechanistic bases of how Bcl3 phosphorylation regulates transcriptional potential of NF-κB and intricate cell physiology, a dysregulation of which can lead to cancers.

Transient interactions modulate the affinity of NF-κB transcription factors for DNA.

The dimeric nuclear factor kappa B (NF-κB) transcription factors (TFs) regulate gene expression by binding to a variety of κB DNA elements with conserved G:C-rich flanking sequences enclosing a degenerate central region. Toward defining mechanistic principles of affinity regulated by degeneracy, we observed an unusual dependence of the affinity of RelA on the identity of the central base pair, which appears to be noncontacted in the complex crystal structures. The affinity of κB sites with A or T at the central position is ~10-fold higher than with G or C. The crystal structures of neither the complexes nor the free κB DNAs could explain the differences in affinity. Interestingly, differential dynamics of several residues were revealed in molecular dynamics simulation studies, where simulation replicates totaling 148 µs were performed on NF-κB:DNA complexes and free κB DNAs. Notably, Arg187 and Arg124 exhibited selectivity in transient interactions that orchestrated a complex interplay among several DNA-interacting residues in the central region. Binding and simulation studies with mutants supported these observations of transient interactions dictating specificity. In combination with published reports, this work provides insights into the nuanced mechanisms governing the discriminatory binding of NF-κB family TFs to κB DNA elements and sheds light on cancer pathogenesis of cRel, a close homolog of RelA.

KANK1 shapes focal adhesions by orchestrating protein binding, mechanical force sensing, and phase separation.

Focal adhesions (FAs) are dynamic protein assemblies that connect cytoskeletons to the extracellular matrix and are crucial for cell adhesion and migration. KANKs are scaffold proteins that encircle FAs and act as key regulators of FA dynamics, but the molecular mechanism underlying their specified localization and functions remains poorly understood. Here, we determine the KANK1 structures in complex with talin and liprin-ß, respectively. These structures, combined with our biochemical and cellular analyses, demonstrate how KANK1 scaffolds the FA core and associated proteins to modulate the FA shape in response to mechanical force. Additionally, we find that KANK1 undergoes liquid-liquid phase separation (LLPS), which is important for its localization at the FA edge and cytoskeleton connections to FAs. Our findings not only indicate the molecular basis of KANKs in bridging the core and periphery of FAs but also provide insights into the LLPS-mediated dynamic regulation of FA morphology.

Effects of food-derived oligopeptide iron chelates on liver injury and gut microbiota homeostasis in iron-deficiency anemia female rats: a pilot study.

Iron deficiency (ID) is the biggest cause of anemia. This pilot study aimed to investigate the effects of food-derived oligopeptide iron chelates on ameliorating liver injury and restoring gut microbiota homeostasis in iron-deficiency anemia (IDA) female rats. Female Sprague-Dawley rats at 21 days old were selected and randomly divided into a control group (N = 4) and an ID model group (N = 16). The ID model group was fed an iron-deficient diet containing 4 mg kg-1 iron for 28 days to generate the IDA rat model and then randomly subdivided into four groups (N = 4 for each group): ID group, ferrous sulfate group, marine fish oligopeptide iron chelate (MCOP-Fe) group, and whey protein oligopeptide iron chelate (WPP-Fe) group. Iron supplements were given to rats in the three intervention groups once per day via intragastric administration for three weeks. After iron supplementation, the hemoglobin levels in the three intervention groups were significantly improved, with the MCOP-Fe and WPP-Fe groups returning to normal. The ALT and AST levels in the ID group increased significantly, while levels in all intervention groups decreased to normal levels. Liver glutathione in the WPP-Fe group was increased, while the activity of superoxide dismutase also tended to be higher. In addition, 16S rRNA gene sequencing showed that IDA resulted in changes to intestinal microbiota. After intervention, the WPP-Fe group showed increased alpha diversity of intestinal microbes. Therefore, MCOP-Fe and WPP-Fe may improve the iron status of IDA female rats as well as ameliorate liver damage, with WPP-Fe showing a greater potential in improving gut microbiota imbalance.

Dietary Intake Levels of Iron, Copper, Zinc, and Manganese in Relation to Cognitive Function: A Cross-Sectional Study.

Background: Previous studies have related circulating levels of trace metal elements, of which dietary intake is the major source, to cognitive outcomes. However, there are still relatively few studies evaluating the associations of dietary intake levels of iron, copper, zinc, and manganese with cognitive function (CF). Methods: We leveraged the data of 6863 participants (mean [standard deviation] age = 66.7 [10.5] years) in the Health and Retirement Study (2013/2014). Dietary intake levels of iron, copper, zinc, and manganese were calculated from a semi-quantitative food frequency questionnaire. CF was assessed using the 27-point modified Telephone Interview for Cognitive Status (TICS). We used linear regression models to calculate the mean differences in global CF scores by quintiles of dietary intake levels of trace metal elements. Results: Among the study participants, the mean (SD) values of daily dietary intake were 13.3 (6.3) mg for iron, 1.4 (0.7) mg for copper, 10.7 (4.6) mg for zinc, and 3.3 (1.6) mg for manganese. Compared with the lowest quintile of dietary iron intake (<8.1 mg), the highest quintile (≥17.7 mg) was associated with a lower cognitive score (-0.50, -0.94 to -0.06, P-trend = 0.007). Higher dietary copper was significantly associated with poorer CF (P-trend = 0.002), and the mean difference in cognitive score between extreme quintiles (≥1.8 vs. <0.8 mg) was -0.52 (95% confidence interval: -0.94 to -0.10) points. We did not observe significant associations for dietary intake of zinc (P-trend = 0.785) and manganese (P-trend = 0.368). Conclusion: In this cross-sectional study, higher dietary intake of iron and copper was related to worse CF, but zinc and manganese intake levels were not significantly associated with CF.

Structures of NF-κB p52 homodimer-DNA complexes rationalize binding mechanisms and transcription activation.

The mammalian NF-κB p52:p52 homodimer together with its cofactor Bcl3 activates transcription of κB sites with a central G/C base pair (bp), while it is inactive toward κB sites with a central A/T bp. To understand the molecular basis for this unique property of p52, we have determined the crystal structures of recombinant human p52 protein in complex with a P-selectin(PSel)-κB DNA (5'-GGGGTGACCCC-3') (central bp is underlined) and variants changing the central bp to A/T or swapping the flanking bp. The structures reveal a nearly two-fold widened minor groove in the central region of the DNA as compared to all other currently available NF-κB-DNA complex structures, which have a central A/T bp. Microsecond molecular dynamics (MD) simulations of free DNAs and p52 bound complexes reveal that free DNAs exhibit distinct preferred conformations, and p52:p52 homodimer induces the least amount of DNA conformational changes when bound to the more transcriptionally active natural G/C-centric PSel-κB, but adopts closed conformation when bound to the mutant A/T and swap DNAs due to their narrowed minor grooves. Our binding assays further demonstrate that the fast kinetics favored by entropy is correlated with higher transcriptional activity. Overall, our studies have revealed a novel conformation for κB DNA in complex with NF-κB and pinpoint the importance of binding kinetics, dictated by DNA conformational and dynamic states, in controlling transcriptional activation for NF-κB.

Effects of lactoprotein iron chelates on iron deficiency anaemia in rats / 预防医学

Objective@#To investigate the effects of lactoprotein iron chelates on rats with iron deficiency anaemia (IDA), so as to provide insights into developing and utilizing novel iron supplements.@*Methods@#Seventy weaning female SPF-graded rats of the SD strain were randomly divided into the control group (A), model group (B), ferrous sulfate group (C), lactoferrin group (D), lactoferrin iron chelate group (E), Casein oligopeptide iron chelate group (F) and whey protein oligopeptide iron chelate group (G), with 10 rats in each group. The rats in group A were fed with normal diet, and the others were fed with poor iron diet for IDA modeling. The corresponding interventions were given by intragastric administration once a day. The iron ion concentrations of group C, E, F and G were 2.0 mg/kg, and the protein and oligopeptide concentrations of group D, E, F and G were 2 000 mg/kg. Body weight and hemoglobin of rats were measured weekly during 21-day intervention. At the end, peripheral blood samples were collected, and blood routine, iron metabolism and liver function indicators were determined. @*Results@#After the intervention, among blood routine indicators, the rats in group C, E, F and G showed elevated hemoglobin, red blood cell, mean corpuscular volume and hematocrit, and decreased free protoporphyrin and mean corpuscular hemoglobin concentration when compared with the rats in group B (all P<0.05); among iron metabolism indicators, the rats in group C, E and G showed elevated serum ferritin, the rats in group C, E, F and G showed elevated serum iron, the rats in group C, D, E, F and G showed decreased unsaturated iron binding capacity and total iron binding capacity when compared with the rats in group B (all P<0.05); among liver function indicators, the rats in group E and G showed decreased alanine transaminase when compared with the rats in group B (both P<0.05). @*Conclusions@#Lactoprotein alone could not completely improve IDA in rats compared with traditional iron supplement (ferrous sulfate). Lactoprotein iron chelate, especially whey protein oligopeptide iron chelate, could significantly improve IDA, iron reserve and liver function damage in rats.

Food-derived bioactive oligopeptide iron complexes ameliorate iron deficiency anemia and offspring development in pregnant rats.

This study aimed to investigate anemia treatment and other potential effects of two food-derived bioactive oligopeptide iron complexes on pregnant rats with iron deficiency anemia (IDA) and their offspring. Rats with IDA were established with a low iron diet and then mated. There were one control group and seven randomly assigned groups of pregnant rats with IDA: Control group [Control, 40 ppm ferrous sulfate (FeSO4)]; IDA model group (ID, 4 ppm FeSO4), three high-iron groups (H-FeSO4, 400 ppm FeSO4; MCOP-Fe, 400 ppm marine fish oligopeptide iron complex; WCOP-Fe, 400 ppm whey protein oligopeptide iron complex) and three low-iron groups (L-FeSO4, 40 ppm FeSO4; MOP-Fe, 40 ppm marine fish oligopeptide iron complex; WOP-Fe, 40 ppm whey protein oligopeptide iron complex). Rats in each group were fed the corresponding special diet during pregnancy until the day of delivery. After different doses of iron supplement, serum hemoglobin, iron, and ferritin levels in rats with IDA were significantly increased to normal levels (P < 0.05). Serum iron levels were significantly lower in two food-derived bioactive oligopeptide low-iron complex groups than in the low FeSO4 group (P<0.05). Liver malondialdehyde levels were significantly increased in the three high-iron groups compared with the other five groups (P < 0.05), and hemosiderin deposition was observed in liver tissue, indicating that the iron dose was overloaded and aggravated the peroxidative damage in pregnant rats. Liver inflammation was reduced in the three low-iron groups. Tumor necrosis factor α secretion was significantly decreased in all groups with supplemented oligopeptide (P < 0.05), with the concentration of tumor necrosis factor α declining to normal levels in the two whey protein oligopeptide iron complex groups. In the marine fish oligopeptide iron complex groups, body length, tail length, and weight of offspring were significantly increased (P < 0.05) and reached normal levels. Therefore, food-derived bioactive oligopeptide (derived from marine fish skin and milk) iron complexes may be an effective type of iron supplement for pregnancy to improve anemia, as well as reduce the side effects of iron overload, and improve the growth and nutritional status of offspring.

Atypical IκB Bcl3 enhances the generation of the NF-κB p52 homodimer.

The NF-κB family of dimeric transcription factors regulate diverse biological functions. Their cellular expression profiles differ, which lead to different concentrations in different cell/tissue types. Although the activation mechanisms of different NF-κB dimers have been widely investigated, there is limited information on specific NF-κB dimers' formation. The NF-κB p52:p52 homodimer regulates an important subset of target genes in cancer cells; however, the molecular mechanism of the generation of this specific homodimer remains unclear. Our study has revealed that the atypical IκB protein, Bcl3, plays an essential role in enhancing the p52:p52 homodimer population which is a unique mechanism to p52 within the NF-κB family. p52 was shown to heterodimerize with four other NF-κB subunits (RelA, RelB, cRel, and p50); all heterodimers, except p52:p50, are significantly more stable than the p52:p52 homodimer. Bcl3 is able to compete with all other NF-κB subunits in cells for efficient p52:p52 homodimer formation which consequently leads to the upregulation of target genes that are involved in cell proliferation, migration, and inflammation, which explain why aberrant activation of Bcl3 and p52 leads to cancer.

Iron Overload and the Risk of Diabetes in the General Population: Results of the Chinese Health and Nutrition Survey Cohort Study.

BACKGROUND: Recent studies have found that there are significant associations between body iron status and the development of diabetes. In the present study, we aimed to analyze the association among iron overload (IO), insulin resistance (IR), and diabetes in Chinese adults, and to explore the sex difference. METHODS: Men and women (age >19 years) who participated in the Chinese Health and Nutrition Survey and did not have diabetes at baseline were followed between 2009 and 2015 (n=5,779). Over a mean of 6 years, 75 participants were diagnosed with incident diabetes. Logistic regression was used to assess the risk factors associated with IO. Cox proportional hazard regression was used to estimate the risk of incident diabetes and to determine whether the risk differed among subgroups. Causal mediation analysis (CMA) was used to explore the mechanism linking IO and diabetes. RESULTS: According to sex-stratified multivariable-adjusted Cox proportional hazards regression, IO increased the risk of incident diabetes. Women with IO had a higher risk of diabetes than men. Subgroup analysis with respect to age showed that the association between IO and diabetes was stronger in older women and younger men (P<0.001). CMA showed that liver injury (alanine transaminase) and lipid metabolism abnormalities (triglyceride, apolipoprotein B) contributed to the association between IO and diabetes. CONCLUSION: IO is associated with diabetes and this association is sex-specific. IO may indirectly induce IR via liver injury and lipid metabolism abnormalities, resulting in diabetes.

Nephrotic-syndrome-associated mutation of KANK2 induces pathologic binding competition with physiological interactor KIF21A.

Nephrotic syndrome (NS) is a common kidney disorder caused by dysfunction of the glomerular filtration barrier. Some genetic mutations identified in NS patients cause amino acid substitutions of kidney ankyrin repeat-containing (KANK) proteins, which are scaffold proteins that regulate actin polymerization, microtubule targeting, and cell adhesion via binding to various molecules, including the kinesin motor protein KIF21A. However, the mechanisms by which these mutations lead to NS are unclear. Here, we unexpectedly found that the eukaryotic translation initiation factor 4A1 (eIF4A1) interacts with an NS-associated KANK2 mutant (S684F) but not the wild-type protein. Biochemical and structural analyses revealed that the pathological mutation induces abnormal binding of eIF4A1 to KANK2 at the physiological KIF21A-binding site. Competitive binding assays further indicated that eIF4A1 can compete with KIF21A to interact with the S684F mutant of KANK2. In cultured mouse podocytes, this S684F mutant interfered with the KANK2/KIF21A interaction by binding to eIF4A1, and failed to rescue the focal adhesion or cell adhesion that had been reduced or morphologically changed by KANK2 knockout. These structural, biochemical, and cellular results not only provide mechanistic explanations for the podocyte defects caused by the S684F mutation, but also show how a gain-of-binding mutation can lead to a loss-of-function effect.

Structural insights into ankyrin repeat-mediated recognition of the kinesin motor protein KIF21A by KANK1, a scaffold protein in focal adhesion.

Kidney ankyrin repeat-containing proteins (KANK1/2/3/4) belong to a family of scaffold proteins, playing critical roles in cytoskeleton organization, cell polarity, and migration. Mutations in KANK proteins are implicated in cancers and genetic diseases, such as nephrotic syndrome. KANK proteins can bind various target proteins through different protein regions, including a highly conserved ankyrin repeat domain (ANKRD). However, the molecular basis for target recognition by the ANKRD remains elusive. In this study, we solved a high-resolution crystal structure of the ANKRD of KANK1 in complex with a short sequence of the motor protein kinesin family member 21A (KIF21A), revealing that the highly specific target-binding mode of the ANKRD involves combinatorial use of two interfaces. Mutations in either interface disrupted the KANK1-KIF21A interaction. Cellular immunofluorescence localization analysis indicated that binding-deficient mutations block recruitment of KIF21A to focal adhesions by KANK1. In conclusion, our structural study provides mechanistic explanations for the ANKRD-mediated recognition of KIF21A and for many disease-related mutations identified in human KANK proteins.

Yap1 plays a protective role in suppressing free fatty acid-induced apoptosis and promoting beta-cell survival.

Mammalian pancreatic ß-cells play a pivotal role in development and glucose homeostasis through the production and secretion of insulin. Functional failure or decrease in ß-cell number leads to type 2 diabetes (T2D). Despite the physiological importance of ß-cells, the viability of ß-cells is often challenged mainly due to its poor ability to adapt to their changing microenvironment. One of the factors that negatively affect ß-cell viability is high concentration of free fatty acids (FFAs) such as palmitate. In this work, we demonstrated that Yes-associated protein (Yap1) is activated when ß-cells are treated with palmitate. Our loss- and gain-of-function analyses using rodent insulinoma cell lines revealed that Yap1 suppresses palmitate-induced apoptosis in ß-cells without regulating their proliferation. We also found that upon palmitate treatment, re-arrangement of F-actin mediates Yap1 activation. Palmitate treatment increases expression of one of the Yap1 target genes, connective tissue growth factor (CTGF). Our gain-of-function analysis with CTGF suggests CTGF may be the downstream factor of Yap1 in the protective mechanism against FFA-induced apoptosis.

Significant reduction of antibiotic consumption and patients' costs after an action plan in China, 2010-2014.

INTRODUCTION: On July 1, 2011, the Chinese government launched a national Action Plan for antibiotic stewardship targeting antibiotic misuse in public hospitals. The aim of this study was to evaluate the impacts of the Action Plan in terms of frequency and intensity of antibiotic utilization and patients costs in public general hospitals. METHODS: Administrative pharmacy data from July 2010 to June 2014 were sampled from 65 public general hospitals and divided into three segments: (1) July 2010 to June 2011 as the preparation period; (2) July 2011 to June 2012 as the intervention period; and (3) July 2012 to June 2014 as the assessment period. The outcome measures included (1) antibiotic prescribing rates; (2) intensity of antibiotic consumption; (3) patients costs; and (4) duration of peri-operative antibiotic treatment in clean surgeries of thyroidectomy, breast, hernia, and orthopedic procedures. Longitudinal and cross-sectional analyses were conducted. RESULTS: Longitudinal analyses showed significant trend changes in the frequency and intensity of antibiotic consumption, the patients' costs on antibiotics, and the duration of antibiotic treatment received by surgical patients undergoing the 4 clean procedures during the intervention period. Cross-sectional analyses showed that the antibiotic prescribing rates were reduced to 35.3% and 12.9% in inpatient and outpatient settings, that the intensity of antibiotic consumption was reduced to 35.9 DDD/100 bed-days, that patients' costs on antibiotics were reduced significantly, and that the duration of peri-operative antibiotic treatment received by surgical patients undergoing the 4 types of clean procedures decreased to less than 24 hour during the assessment period. CONCLUSION: The Action Plan, as a combination of managerial and professional strategies, was effective in reducing the frequency and intensity of antibiotic consumption, patients' costs on antibiotics, and the duration of peri-operative antibiotic treatment in the 4 clean surgeries.

Thyroid-stimulating hormone regulates hepatic bile acid homeostasis via SREBP-2/HNF-4α/CYP7A1 axis.

BACKGROUND & AIMS: Bile acids (BAs) play a crucial role in dietary fat digestion and in the regulation of lipid, glucose, and energy metabolism. Thyroid-stimulating hormone (TSH) is a hormone produced by the anterior pituitary gland that directly regulates several metabolic pathways. However, the impact of TSH on BA homeostasis remains largely unknown. METHODS: We analyzed serum BA and TSH levels in healthy volunteers under strict control of caloric intake. Thyroidectomized rats were administered thyroxine and injected with different doses of TSH. Tshr(-/-) mice were supplemented with thyroxine, and C57BL/6 mice were injected with Tshr-siRNA via the tail vein. The serum BA levels, BA pool size, and fecal BA excretion rate were measured. The regulation of SREBP-2, HNF-4α, and CYP7A1 by TSH were analyzed using luciferase reporter, RNAi, EMSA, and CHIP assays. RESULTS: A negative correlation was observed between the serum levels of TSH and the serum BA levels in healthy volunteers. TSH administration led to a decrease in BA content and CYP7A1 activity in thyroidectomized rats supplemented with thyroxine. When Tshr was silenced in mice, the BA pool size, fecal BA excretion rate, and serum BA levels all increased. Additionally, we found that HNF-4α acts as a critical molecule through which TSH represses CYP7A1 activity. We further confirmed that the accumulation of mature SREBP-2 protein could impair the capacity of nuclear HNF-4α to bind to the CYP7A1 promoter, a mechanism that appears to mediate the effects of TSH. CONCLUSIONS: TSH represses hepatic BA synthesis via a SREBP-2/HNF-4α/CYP7A1 signaling pathway. This finding strongly supports the notion that TSH is an important pathophysiological regulator of liver BA homeostasis independently of thyroid hormones.