Celastrol Induces Apoptosis and Autophagy via the AKT/mTOR Signaling Pathway in the Pituitary ACTH-secreting Adenoma Cells

Objective Pituitary adrenocorticotropic hormone(ACTH)-secreting adenoma is a relatively intractable endocrine adenoma that can cause a range of severe metabolic disorders and pathological changes involving multiple systems.Previous studies have shown that celastrol has antitumor effects on a variety of tumor cells via the AKT/mTOR signaling.However,whether celastrol has pronounced antitumor effects on pituitary ACTH-secreting adenoma is unclear.This study aimed to identify a new effective therapeutic drug for pituitary ACTH-secreting adenoma.Methods Mouse pituitary ACTH-secreting adenoma cells(AtT20 cells)were used as an experimental model in vitro and to establish a xenograft tumor model in mice.Cells and animals were administered doses of celastrol at various levels.The effects of celastrol on cell viability,migration,apoptosis and autophagy were then examined.Finally,the potential involvement of AKT/mTOR signaling in celastrol’s mechanism was assessed.Results Celastrol inhibited the proliferation and migration of pituitary adenoma cells in a time-and concentration-dependent manner.It blocked AtT20 cells in the G0/G1 phase,and induced apoptosis and autophagy by downregulating the AKT/mTOR signaling pathway.Similar results were obtained in mice.Conclusion Celastrol exerts potent antitumor effects on ACTH-secreting adenoma by downregulating the AKT/mTOR signaling in vitro and in vivo.

Arg-Ser-⁷⁷⁵, ⁷⁹²and ⁸²³in Spacer Region of ADAMTS-18 Is Critical for Thrombin Cleavage

Cleavage of ADAMTS-18 by thrombin represents a new mechanism of platelet thrombus clearance via the release of active ~45-kDa C-terminal fragments that induces oxidative platelet fragmentation. The exact cleavage sites remain unclear, but Arg (R)775/Ser (S)776 in spacer region of ADAMTS-18 has been shown to be one of the cleavage sites of thrombin. Here, we demonstrate that R792/S793 and R823/S824 are also thrombin cleavage sites by sequence analysis, amino acid mutation and mass spectrometry assay. All these cleavage sites are thrombin-specific and insensitive to other enzymes tested (e.g. cathepsin D or trypsin). Simultaneous mutation of R775, 792, 823 to S775, 792, 823 in ADAMTS-18 completely abrogated the cleavage by thrombin and the generation of active C-terminal 45-kDa fragments. Together with previous study, a total of three thrombin-specific cleavage sites have been identified in spacer region of ADAMTS-18.

Modulating effects of acyl-CoA synthetase 5-derived mitochondrial Wnt2B palmitoylation on intestinal Wnt activity

AIM:To investigate the role of acyl-CoA synthetase 5(ACSL5)activity in Wnt signaling in intestinal surface epithelia.METHODS:Several cell lines were used to investigate the ACSL5-dependent expression and synthesis of Wnt2B,a mitochondrially expressed protein of the Wnt signaling family.Wnt activity was functionally assessed with a luciferase reporter assay.ACSL5-related biochemical Wnt2B modifications were investigatedwith a modified acyl-exchange assay.The findings from the cell culture models were verified using an Apcmin/+mouse model as well as normal and neoplastic diseased human intestinal tissues.RESULTS:In the presence of ACSL5,Wnt2B was unable to translocate into the nucleus and was enriched in mitochondria,which was paralleled by a significant decrease in Wnt activity.ACSL5-dependent S-palmitoylation of Wnt2B was identified as a molecular reason for mitochondrial Wnt2B accumulation.In cell culture systems,a strong relation of ACSL5 expression,Wnt2B palmitoylation,and degree of malignancy were found.Using normal mucosa,the association of ACSL5 and Wnt2B was seen,but in intestinal neoplasias the mechanism was only rudimentarily observed.CONCLUSION:ACSL5 mediates antiproliferative activities via Wnt2B palmitoylation with diminished Wnt activity.The molecular pathway is probably relevant for intestinal homeostasis,overwhelmed by other pathways in carcinogenesis.

Lrp1 in osteoblasts controls osteoclast activity and protects against osteoporosis by limiting PDGF–RANKL signaling

Skeletal health relies on architectural integrity and sufficient bone mass, which are maintained through a tightly regulated equilibrium of bone resorption by osteoclasts and bone formation by osteoblasts. Genetic studies have linked the gene coding for low-density lipoprotein receptor-related protein1(Lrp1) to bone traits but whether these associations are based on a causal molecular relationship is unknown. Here, we show that Lrp1 in osteoblasts is a novel regulator of osteoclast activity and bone mass.Mice lacking Lrp1 specifically in the osteoblast lineage displayed normal osteoblast function but severe osteoporosis due to highly increased osteoclast numbers and bone resorption. Osteoblast Lrp1 limited receptor activator of NF-κB ligand(RANKL) expression in vivo and in vitro through attenuation of platelet-derived growth factor(PDGF-BB) signaling. In co-culture, Lrp1-deficient osteoblasts stimulated osteoclastogenesis in a PDGFRβ-dependent manner and in vivo treatment with the PDGFR tyrosine kinase inhibitor imatinib mesylate limited RANKL production and led to complete remission of the osteoporotic phenotype. These results identify osteoblast Lrp1 as a key regulator of osteoblast-to-osteoclast communication and bone mass through a PDGF–RANKL signaling axis in osteoblasts and open perspectives to further explore the potential of PDGF signaling inhibitors in counteracting bone loss as well as to evaluate the importance of functional LRP1 gene variants in the control of bone mass in humans.

Identification of two migratory colon ILC2 populations differentially expressing IL-17A and IL-5/IL-13

Group 2 innate lymphoid cells(ILC2s)play important tissue resident roles in anti-parasite immunity,allergic immune response,tissue homeostasis,and tumor immunity.ILC2s are considered tissue resident cells with little proliferation at steady state.Recent studies have shown that a subset of small intestinal ILC2s could leave their residing tissues,circulate and migrate to different organs,including lung,liver,mesenteric LN and spleen,upon activation.However,it remains unknown whether other ILC populations with migratory behavior exist.In this study,we find two major colon ILC2 populations with potential to migrate to the lung in response to IL-25 stimulation.One subset expresses IL-17A and resembles inflammatory ILC2s(iILC2s)but lacks CD27 expression,whereas the other expresses CD27 but not IL-17A.In addition,the IL-17A^(+)ILC2s express lower levels of CD127,CD25,and ST2 than CD27^(+)ILC2s,which express higher levels of IL-5 and IL-13.Surprisingly,we found that both colon ILC2 populations still maintained their colonic features of preferential expression of IL-17A and CD27,IL-5/IL-13,respectively.Together,our study identifies two migratory colon ILC2 subsets with unique surface markers and cytokine profiles which are critical in regulating lung and colon immunity and homeostasis.

Over-expression of small ubiquitin-like modifier proteases 1 predicts chemo-sensitivity and poor survival in non-small cell lung cancer

Background Non-small cell lung cancer （NSCLC） is one of the most common malignant tumors.Despite the advances in therapy over the years,its mortality remains high.The aim of this study was to evaluate the expression of small ubiquitin-like modifier （SUMO） proteases 1 （SENP1） in NSCLC tissues and its role in the regulation of vascular endothelial growth factor （VEGF） expression.We also investigated the association between the expression level of SENP1 and the clinicopathological features and survival of the patients.Methods A SENP1 small interfering RNA （siRNA） was constructed and transfected into the NSCLC cells.VEGF gene expression was analyzed by real-time polymerase chain reaction （RT-PCR）.Immunohistochemistry staining was used to assess the expression of SENP1 in 100 NSCLC patients and its association with the clinicopathological features and survival was analyzed.Results VEGF expression was significantly higher in NSCLC tissues than in normal lung tissues.Inhibition of SENP1 by siRNA was associated with decreased VEGF expression.SENP1 was over-expressed in 55 of the 100 NSCLC samples （55％） and was associated with a moderate and low histological tumor grade （3.6％,38.2％,and 58.2％ in high,moderate and low differentiated tumors,respectively,P=0.046）,higher T stage （10.9％ in T1,and 89.1％ in T2 and T3 tumor samples,P ＜0.001）and TNM stage （10.9％ in stage Ⅰ,and 89.1％ in stages Ⅱ and Ⅲ tumor samples,P ＜0.001）.The rate of lymph node metastasis was significantly higher in the SENP1 over-expression group （76.4％） than that in the SENP1 low expression group （33.3％,P ＜0.001）.Sixty three patients received postoperative chemotherapy,including 34 with SENP1 over-expression and 29 with SENP1 low expression.Among the 34 patients with SENP1 over-expression,22 （64.7％） patients developed recurrence or metastasis,significantly higher than those in the low expression group 27.6％ （8/29） （P=0.005）.Multivariate Cox regression analysis showed that lymph node metastasis （P=0.015）,TNM stage （P=-0.001）,and SENP1 expression level （P=0.002） were independent prognostic factors for the survival of NSCLC patients.Conclusions SENP1 may be a promising predictor of survival,a predictive factor of chemo-sensitivity for NSCLC patients,and potentially a desirable drug target for lung carcinoma target therapy.

Establishment and implementation of integrated course of molecule,cell and tissue

The organ and system-centered integrated curriculum has become a mainstream model of international medical education and an exploring model of Chinese medical education. However,there is no report on whether or how to integrate teaching contents of biological disciplines under this model in Chinese medical schools. Shanghai Jiao Tong University School of Medicine offers an integrated course named molecule,cell and tissue,which combines biochemistry,molecular biology,and cell biology with histology and physiology. This course not only reflects the integration of basic medicine and biology,but also focuses on molecular and cellular basis of structures and functions of human organs and systems. The course Molecule,Cell and Tissue breaks the boundaries of disciplines, provides integrated contents by deleting repeated contents,forms integrated key knowledge points,builds a reasonable integrated teaching team,modifies teaching methods,and adopts student-centered teaching models such as group report,co-teaching by teacher and students,and team-based learning. After 5 years of practice,this course has achieved satisfying teaching effect and can provide ideas and reference for the reform of Chinese basic medical education.

Alternative splicing and related RNA binding proteins in human health and disease

Alternative splicing(AS)serves as a pivotal mechanism in transcriptional regulation,engendering transcript diversity,and modifications in protein structure and functionality.Across varying tissues,developmental stages,or under specific conditions,AS gives rise to distinct splice isoforms.This implies that these isoforms possess unique temporal and spatial roles,thereby associating AS with standard biological activities and diseases.Among these,AS-related RNA-binding proteins(RBPs)play an instrumental role in regulating alternative splicing events.Under physiological conditions,the diversity of proteins mediated by AS influences the structure,function,interaction,and localization of proteins,thereby participating in the differentiation and development of an array of tissues and organs.Under pathological conditions,alterations in AS are linked with various diseases,particularly cancer.These changes can lead to modifications in gene splicing patterns,culminating in changes or loss of protein functionality.For instance,in cancer,abnormalities in AS and RBPs may result in aberrant expression of cancer-associated genes,thereby promoting the onset and progression of tumors.AS and RBPs are also associated with numerous neurodegenerative diseases and autoimmune diseases.Consequently,the study of AS across different tissues holds significant value.This review provides a detailed account of the recent advancements in the study of alternative splicing and AS-related RNA-binding proteins in tissue development and diseases,which aids in deepening the understanding of gene expression complexity and offers new insights and methodologies for precision medicine.

SENP2 negatively regulates cellular antiviral response by deSUMOylating IRF3 and conditioning it for ubiquitination and degradation

Transcription factor IRF3-mediated type I interferon induction is essential for antiviral innate immunity.We identified the deSUMOylating enzyme Sentrin/SUMO-specific protease(SENP)2 as a negative regulator of virus-triggered IFN-b induction.Overexpression of SENP2 caused IRF3 deSUMOylation,K48-linked ubiquitination,and degradation,whereas depletion of SENP2 had opposite effects.Both the SUMOylation and K48-linked ubiquitination of IRF3 occurred at lysines 70 and 87,and these processes are competitive.The level of virus-triggered IFN-b was markedly up-regulated and viral replication was reduced in SENP2-deficient cells comparing with wild-type controls.Our findings suggest that SENP2 regulates antiviral innate immunity by deSUMOylating IRF3 and conditioning it for ubiquitination and degradation,and provide an example of cross-talk between the ubiquitin and SUMO pathways in innate immunity.

Deficiency of the G protein Gαq ameliorates experimental autoimmune encephalomyelitis with impaired DC-derived IL-6 production and Th17 differentiation

Many G protein-coupled receptors （GPCRs） are reported to be involved in the pathogenesis of multiple sclerosis （MS）, and -40% of all identified GPCRs rely on the Gaq/11 G protein family to stimulate inositol lipid signaling. However, the function of Ga subunits in MS pathogenesis is still unknown. In this study, we attempted to determine the role of Gaq in the pathogenesis of experimental autoimmune encephalomyelitis （EAE）, a well-known mouse model of MS. We discovered that compared with wild-type mice, Gaq-knockout mice exhibited less severe EAE symptoms, with lower clinical scores, reduced leukocyte infiltration and less extensive demyelination. Moreover, a significantly lower percentage of Th17 cells, one of the key players in MS pathogenesis, was observed in Gaq-knockout EAE mice. Studies in vitro demonstrated that deficiency of Gaq in CD4＋ T cells directly impaired Th17 differentiation. In addition, deficiency of Gaq significantly impaired DC-derived IL-6 production, thus inhibiting Th17 differentiation and the Gaq-PLCβ-PKC and Gaq-MAPKs signaling pathways involved in the reduced IL-6 production by DCs. In summary, our data highlighted the critical role of Gaq in regulating Th17 differentiation and MS oathogenesis.

Conversion of mouse fibroblasts into oligodendrocyte progenitor-like cells through a chemical approach

Transplantation of oligodendrocyte progenitor cells (OPCs) is a promising way for treating demyelinating diseases. However, generation of scalable and autologous sources of OPCs has proven difficult. We previously established a chemical condition M9 that could specifically initiate neural program in mouse embryonic fibroblasts. Here we found that M9 could induce the formation of colonies that undergo mesenchymal-to-epithelial transition at the early stage of reprogramming. These colonies may represent unstable and neural lineage-restricted intermediates that have not established a neural stem cell identity. By modulating the culture signaling recapitulating the principle of OPC development, these intermediate cells could be reprogrammed towards OPC fate. The chemical-induced OPC-like cells (ciOPLCs) resemble primary neural stem cell-derived OPCs in terms of their morphology, gene expression, and the ability of self-renewal. Upon differentiation, ciOPLCs could produce functional oligodendrocytes and myelinate the neuron axons in vitro, validating their OPC identity molecularly and functionally. Therefore, our study provides a non-integrating approach to OPC reprogramming that may ultimately provide an avenue to patient-specific cell-based or in situ regenerative therapy.

Receptor-mediated inhibitory mechanisms and the regulation of platelet function

Platelets are derived from megakaryocytes;they circulate in mammalian blood vessels and play essential roles in hemostasis and thrombosis.When platelets encounter injury,they respond by triggering the formation of a blood clot to prevent blood loss(hemostasis).While this is vital for survival,

DOT1L-long enhances breast cancer metastasis

Objective· To investigate the histone methyltransferase capability of DOT1L-long form and its role in breast cancer metastasis. Methods· The existence of DOT1L-long form was confirmed by PCR, and the mRNA level of DOT1L was tested by real-time PCR. In HEK293T cells in which DOT1L canonical and DOT1L-long were overexpressed respectively, Western blotting was used to test the expression level of DOT1L and the histone methyltransferase capability. In the MCF10A cell line with inducible expression of DOT1L-long, real-time PCR was used to detect the mRNA level of epithelial-mesenchymal transition(EMT) marker, and transwell assay was used to detect the migration of breast cancer cells in which the expression level of DOT1L is low or high. Results· PCR demonstrated the existence of DOT1L-long form, and real-time PCR showed it widely exists in HCT116, T98G, MCF10A cells, etc. Western blotting showed the expression of DOT1L-long form and its H3K79 methyltransferase activity. In MCF10A cells in which overexpressed canonical DOT1L and DOT1L-long, mRNA levels of N-cadherin and fibronectine increased. Transwell showed canonical DOT1L and DOT1L-long both substantially increased the migration of breast cancer cells. Conclusion· The existence of DOT1L-long was confirmed and investigated, which is 202 amino acids longer than the canonical DOT1L, and is coded by a new exon, located between exon 27 and 28. Further, the DOT1L-long has H3K79 methyltransferase activity, and is able to promote breast cancer metastasis.

Experience in the modular teaching of the integrated course of metabolism and energy

The teaching of eight-year clinical medicine program of Shanghai Jiao Tong University School of Medicine was reformed since 2009 to replace the traditional teaching model with modular teaching. As one of reformed courses,the metabolism and energy course combines biochemistry and physiology related knowledge points and endeavors to overcome shortcomings of traditional basic medical knowledge education,such as simple learning contents,isolation between basic medicine and clinical medicine,simple teaching methods of teachers,and passive learning methods of students. After 6 years of teaching practice,the new teaching model has been recognized by both teachers and students and the teaching quality improves comprehensively,but there are still some shortcomings that need to be overcome. This paper summarizes the gain and loss of the modular teaching of integrated course of metabolism and energy,so as to provide reference for extending the reform of modular teaching and further improving the teaching quality.

Lactate: an intracellular metabolite regulates cell cycle progression

The Chouchani lab recently reported in Nature that a dynamic intracellular lactate is a physiological regulator for cell cycle progress.They also showed that accumulated lactate in cell mitosis directly binds and inhibits Sentrin/SUMO-specific pro-tease 1 to enrich SUMO2/3-modification of anaphase-promot-ing complex 4(APC4),which promotes the degradation of APC/C complexes,leading to mitosis exit.

Proton production,regulation and pathophysiological roles in the mammalian brain

The recent demonstration of proton signaling in C. elegans muscle contraction suggests a novel mechanism for proton-based intercellular communication and has stimulated enthusiasm for exploring proton signaling in higher organ- isms. Emerging evidence indicates that protons are produced and regulated in localized space and time. Furthermore, identification of proton regulators and sensors in the brain leads to the speculation that proton production and regulation may be of major importance for both physiological and pathological functions ranging from nociception to learning and memory. Extracellular protons may play a role in signal transmission by not only acting on adjacent ceils hut also af- fecting the cell from which they were released. In this review, we summarize the upstream and downstream pathways of proton production and regulation in the mammalian brain, with special emphasis on the proton extruders and sensors that are critical in the homeostatic regulation of pH, and discuss their potential roles in proton signaling under normal and pathophysiological conditions.

Cancer metabolism and tumor microenvironment:fostering each other?

The changes associated with malignancy are not only in cancer cells but also in environment in which cancer cells live.Metabolic reprogramming supports tumor cells’high demand of biogenesis for their rapid proliferation,and helps tumor cells to survive under certain genetic or environmental stresses.Emerging evidence suggests that metabolic alteration is ultimately and tightly associated with genetic changes,in particular the dysregulation of key oncogenic and tumor suppressive signaling pathways.Cancer cells activate HIF signaling even in the presence of oxygen and in the absence of growth factor stimulation.This cancer metabolic phenotype,described firstly by German physiologist Otto Warburg,ensures enhanced glycolytic metabolism for the biosynthesis of macromolecules.The conception of metabolite signaling,i.e.,metabolites are regulators of cell signaling,provides novel insights into how reactive oxygen species(ROS)and other metabolites deregulation may regulate redox homeostasis,epigenetics,and proliferation of cancer cells.Moreover,the unveiling of noncanonical functions of metabolic enzymes,such as the moonlighting functions of phosphoglycerate kinase 1(PGK1),reassures the importance of metabolism in cancer development.The metabolic,microRNAs,and ncRNAs alterations in cancer cells can be sorted and delivered either to intercellular matrix or to cancer adjacent cells to shape cancer microenvironment via media such as exosome.Among them,cancer microenvironmental cells are immune cells which exert profound effects on cancer cells.Understanding of all these processes is a prerequisite for the development of a more effective strategy to contain cancers.

Emerging approaches to probing ion channel structure and function

Ion channels,as membrane proteins,are the sensors of the cell.They act as the first line of communication with the world beyond the plasma membrane and transduce changes in the external and internal environments into unique electrical signals to shape the responses of excitable cells.Because of their importance in cellular communication,ion channels have been intensively studied at the structural and functional levels.Here,we summarize the diverse approaches,including molecular and cellular,chemical,optical,biophysical,and computational,used to probe the structural and functional rearrangements that occur during channel activation（or sensitization）,inactivation（or desensitization）,and various forms of modulation.The emerging insights into the structure and function of ion channels by multidisciplinary approaches allow the development of new pharmacotherapies as well as new tools useful in controlling cellular activity.

A role of IL-25,a sibling of IL-17,in triggering psoriatic skin inflammation

Interleukin 25(IL-25)expressed in epithelial cells,basophils,eosinophils,mast cells and tuft cells is a member of the IL-17 cytokine family.Dong and colleagues newly found that IL-25 expressed in keratinocytes under pathological conditions may play a critical role in psoriatic skin inflammation and autoimmunity driven by IL-17a.