Effects of chromium nanoparticle dosage on growth,body composition,serum hormones and tissue chromium in Sprague-Dawley rats

This 6-week study was conducted to evaluate the effects of seven different levels of dietary chromium (Cr) (0,75,150,300,450,600,and 1200 ppb Cr) in the form of Cr nanoparticle (CrNano) on growth,body composition,serum hormones and tissue Cr in Sprague-Dawley (SD) rats. Seventy male SD rats (average initial body weight of (83.2±4.4) g) were randomly assigned to seven dietary treatments (n=10). At the end of the trial,body composition was assessed via dual energy X-ray absorptiometry (DEXA). All rats were then sacrificed to collect samples of blood,organs and tissues for determination of serum hormones and tissue Cr contents. The results indicated that lean body mass was significantly increased (P<0.05) due to the addition of 300 and 450 ppb Cr from CrNano. Supplementation of 150,300,450,and 600 ppb Cr decreased (P<0.05) percent body fat significantly. Average daily gain was increased (P<0.05) by addition of 75,150,and 300 ppb Cr and feed efficiency was increased (P<0.05) by supplementation of 75,300,and 450 ppb Cr. Addition of 300 and 450 ppb Cr decreased (P<0.05) the insulin level in serum greatly. Cr contents in liver and kidney were greatly increased (P<0.05) by the addition of Cr as CrNano in the dosage of from 150 ppb to 1 200 ppb. In addition,Supplementation of 300,450,and 600 ppb Cr significantly increased (P<0.05) Cr content in the hind leg muscle. These results suggest that supplemental CrNano has beneficial effects on growth performance and body composition,and increases tissue Cr concentration in selected muscles.

Early inoculation with caecal fermentation broth alters small intestine morphology,gene expression of tight junction proteins in the ileum,and the caecal metabolomic profiling of broilers

Background:The establishment of stable microbiota in early life is beneficial to the individual.Changes in the intestinal environment during early life play a crucial role in modulating the gut microbiota.Therefore,early intervention to change the intestinal environment can be regarded as a new regulation strategy for the growth and health of poultry.However,the effects of intestinal environmental changes on host physiology and metabolism are rarely reported.This study was conducted to investigate the effects of early inoculation with caecal fermentation broth on small intestine morphology,gene expression of tight junction proteins in the ileum,and cecum microbial metabolism of broilers.Results:Our data showed that early inoculation with caecal fermentation broth could improve intestine morphology.The small intestine villus height was significantly increased(P<0.05)in the intervened broilers compared to the control group,especially on day 28.A similar result was observed in the ratio of villus height to crypt depth(P<0.05).Meanwhile,we found early inoculation significantly increased(P<0.05)the expression levels of zonula occludens-1(ZO1)on days 14 and 28,claudin-1(CLDN1)on day 28,whereas the gene expression of claudin-2(CLDN2)was significantly decreased(P<0.05)on days 14 and 28.Gas chromatography time-of-flight/mass spectrometry(GC-TOF/MS)technology was further implemented to systematically evaluate the microbial metabolite profiles.Principal component analysis(PCA)and orthogonal partial least squares discriminant analysis(OPLS-DA)displayed a distinct trend towards separation between the fermentation broth group(F group)and the control group(C group).The differentially expressed metabolites were identified,and they were mainly functionally enriched in beta-alanine metabolism and biosynthesis of unsaturated fatty acids.In addition,1,3-diaminopropane was selected as a key biomarker that responded to early inoculation with caecal fermentation broth.Conclusions:These results provide insight into intestinal metabolomics and confirm that early inoculation with caecal fermentation broth can be used as a potential strategy to improve intestinal health of broilers.

LncFASA promotes cancer ferroptosis via modulating PRDX1 phase separation

Ferroptosis, a unique type of non-apoptotic cell death resulting from iron-dependent lipid peroxidation, has a potential physiological function in tumor suppression, but its underlying mechanisms have not been fully elucidated. Here, we report that the long non-coding RNA(lncRNA) LncFASA increases the susceptibility of triple-negative breast cancer(TNBC) to ferroptosis. As a tumor suppressor, LncFASA drives the formation of droplets containing peroxiredoxin1(PRDX1), a member of the peroxidase family, resulting in the accumulation of lipid peroxidation via the SLC7A11-GPX4 axis. Mechanistically, LncFASA directly binds to the Ahpc-TSA domain of PRDX1, inhibiting its peroxidase activity by driving liquid-liquid phase separation, which disrupts intracellular ROS homeostasis. Notably, high LncFASA expression indicates favorable overall survival in individuals with breast cancer, and LncFASA impairs the growth of breast xenograft tumors by modulating ferroptosis. Together, our findings illustrate the crucial role of this lncRNA in ferroptosis-mediated cancer development and provide new insights into therapeutic strategies for breast cancer.

p53 coordinates with △133p53 isoform to promote cell survival under low-level oxidative stress

Dear Editor,Reactive oxygen species(ROS)can serve as intracellular signals that promote cell proliferation and survival at sub-toxic levels,or function as toxic substances that cause cell death and senescence at high levels(Weinberg and Chandel,2009).p53 plays a key role in the control of cellular response to ROS by upregulating the expression of either antioxidant genes under low level of oxidative stresses or pro-oxidative and apoptotic genes under high level of stresses(Vigneron and Vousden,2010;Hafsi and Hainaut,2011).However,how p53 differentially regulates gene expression in response to different ROS level remains elusive.△133p53 is an N-terminal truncated form of p53(Bourdon et al.,2005)and functions to antagonize p53 apoptotic activity and to promote DNA double-strand break repair(Chen et al.,2009;Aoubala et al.,2011;Gong et al.,2015).In this study,we investigated the functional interaction between p53 and △133p53 in response to various levels of ROS.

Stability and function of RCL1 are dependent on the interaction with BMS1

During ribosome biogenesis,the small subunit(SSU)processome is responsible for 40S assembly.The BMS1/RCL1 complex is a core component of the SSU processome that plays an important role in 18S rRNA processing and maturation.Genetic studies using zebrafish mutants indicate that both Bms1-like(Bms1l)and Rcl1 are essential for digestive organ development.In spite of vital functions of this complex,the mutual dependence of these two nucleolar proteins for the stability and function remains elusive.In this study,we identified an RCL1-interacting domain in BMS1,which is conserved in zebrafish and humans.Moreover,both the protein stability and nucleolar entry of RCL1 depend on its interaction with BMS1,otherwise RCL1 degraded through the ubiquitination-proteasome pathway.Functional studies revealed that overexpression of RCL1 in BMS1-knockdown cells can partially rescue the defects in 18S rRNA processing and cell proliferation,and hepatocyte-specific overexpression of Rcl1 can resume zebrafish liver development in the bms1l substitution mutant bms1l^(sq163/sq163)but not in the knockout mutant bms1l^(zju1/zju1),which is attributed to the nucleolar entry of Rcl1 in the former mutant.Our data demonstrate that BMS1 and RCL1 interaction is essential for not only pre-rRNA processing but also the communication between ribosome biogenesis and cell cycle regulation.

Loss-of-function of zebrafish cdt1 causes retarded body growth and underdeveloped gonads resembling human Meier-Gorlin syndrome

The cell cycle consists of four distinct phases:GO/Gl,S(DNA synthesis),G2,and M(mitosis).The Gl to S transition is typified by an accumulation of 4',6-diamidino-2-phenylindole(DAPI)signal that indicates the rapid DNA synthesis initiated at special sites on DNA,generally called the Ori(origin of replication)(Alfa et al.,1989).

Zebrafish hhex-null mutant develops an intrahepatic intestinal tube due to de-repression of cdx1b and pdx1

The hepatopancreatic duct (HPD) system links the liver and pancreas to the intestinal tube and is composed of the extrahepatic biliary duct, gallbladder, and pancreatic duct. Haematopoietically expressed-homeobox (Hhex) protein plays an essential role in the establishment of HPD;however, the molecular mechanism remains elusive. Here, we show that zebrafish hhex-null mutants fail to develop the HPD system characterized by lacking the biliary marker Annexin A4 and the HPD marker sox9b. The hepatobiliary duct part of the mutant HPD system is replaced by an intrahepatic intestinal tube characterized by expressing the intestinal marker fatty acid-binding protein 2a (fabp2a). Cell lineage analysis showed that this intrahepatic intestinal tube is not originated from hepatocytes or cholangiocytes. Further analysis revealed that cdx1b and pdx1 are expressed ectopically in the intrahepatic intestinal tube and knockdown of cdx1b and pdx1 could restore the expression of sox9b in the mutant. Chromatin-immunoprecipitation analysis showed that Hhex binds to the promoters of pdx1 and cdx1b genes to repress their expression. We therefore propose that Hhex, Cdx1b, Pdx1, and Sox9b form a genetic network governing the patterning and morphogenesis of the HPD and digestive tract systems in zebrafish.

Nucleolar GTPase Bms1 displaces Ttf1 from RFB-sites to balance progression of rDNA transcription and replication

18S,5.8S,and 28S ribosomal RNAs(rRNAs)are cotranscribed as a pre-ribosomal RNA(pre-rRNA)from the rDNA by RNA polymerase I whose activity is vigorous during the S-phase,leading to a conflict with rDNA replication.This conflict is resolved partly by replication-fork-barrier(RFB)-sites sequences located downstream of the rDNA and RFB-binding proteins such as Ttf1.However,how Ttf1 is displaced from RFB-sites to allow replication fork progression remains elusive.Here,we reported that loss-of-function of Bms1l,a nucleolar GTPase,upregulates rDNA transcription,causes replication-fork stall,and arrests cell cycle at the S-to-G2 transition;however,the G1-to-S transition is constitutively active characterized by persisting DNA synthesis.Concomitantly,ubf,tif-IA,and taf1b marking rDNA transcription,Chk2,Rad51,and p53 marking DNA-damage response,and Rpa2,PCNA,Fen1,and Ttf1 marking replication fork stall are all highly elevated in bms1l mutants.We found that Bms1 interacts with Ttf1 in addition to Rc1l.Finally,we identified RFB-sites for zebrafish Ttf1 through chromatin immunoprecipitation sequencing and showed that Bms1 disassociates the Ttf1–RFB complex with its GTPase activity.We propose that Bms1 functions to balance rDNA transcription and replication at the S-phase through interaction with Rcl1 and Ttf1,respectively.TTF1 and Bms1 together might impose an S-phase checkpoint at the rDNA loci.

Capn3 depletion causes Chk1 and Wee1 accumulation and disrupts synchronization of cell cycle reentry during liver regeneration after partial hepatectomy

Recovery of liver mass to a healthy liver donor by compensatory regeneration after partial hepatectomy(PH)is a prerequisite for liver transplantation.Synchronized cell cycle reentry of the existing hepatocytes after PH is seemingly a hallmark of liver compensatory regeneration.Although the molecular control of the PH-triggered cell cycle reentry has been extensively studied,little is known about how the synchronization is achieved after PH.The nucleolus-localized protein cleavage complex formed by the nucleolar protein Digestive-organ expansion factor(Def)and cysteine proteinase Calpain 3(Capn3)has been implicated to control wounding healing during liver regeneration through selectively cleaving the tumor suppressor p53 in the nucleolus.However,whether the Def-Capn3 complex participates in regulating the synchronization of cell cycle reentry after PH is unknown.In this report,we generated a zebrafish capn3b null mutant(capn3b^(Δ19Δ14)).The homozygous mutant was viable and fertile,but suffered from a delayed liver regeneration after PH.Delayed liver regeneration in capn3b^(Δ19Δ14)was due to disruption of synchronized cell proliferation after PH.Mass spectrometry(MS)analysis of nuclear proteins revealed that a number of negative regulators of cell cycle are accumulated in the capn3b^(Δ19Δ14)liver after PH.Moreover,we demonstrated that Check-point kinase 1(Chk1)and Wee1,two key negative regulators of G2 to M transition,are substrates of Capn3.We also demonstrated that Chk1 and Wee1 were abnormally accumulated in the nucleoli of amputated capn3bΔ19Δ14 liver.In conclusion,our findings suggest that the nucleolar-localized Def-Capn3 complex acts as a novel regulatory pathway for the synchronization of cell cycle reentry,at least partially,through inactivating Chk1 and Wee1 during liver regeneration after PH.

All routes lead to Rome:multifaceted origin of hepatocytes during liver regeneration

Liver is the largest internal organ that serves as the key site for various metabolic activities and maintenance ofhomeostasis. Liver diseases are great threats to human health. The capability of liver to regain its mass after partialhepatectomy has widely been applied in treating liver diseases either by removing the damaged part of a diseasedliver in a patient or transplanting a part of healthy liver into a patient. Vast efforts have been made to study thebiology of liver regeneration in different liver-damage models. Regarding the sources of hepatocytes during liverregeneration, convincing evidences have demonstrated that different liver-damage models mobilized differentsubtype hepatocytes in contributing to liver regeneration. Under extreme hepatocyte ablation, biliary epithelial cellscan undergo dedifferentiation to liver progenitor cells (LPCs) and then LPCs differentiate to produce hepatocytes.Here we will focus on summarizing the progresses made in identifying cell types contributing to producing newhepatocytes during liver regeneration in mice and zebrafish.