Oncogenic Signaling Adaptor Proteins

Signal transduction pathways activated by receptor tyrosine kinases （RTK） play a critical role in many aspects of cell function. Adaptor proteins serve an important scaffolding function that facilitates key signaling transduction events downstream of RTKs. Recent work integrating both structural and functional genomic approaches has identified several adaptor proteins as new oncogenes. In this review, we locus on the discovery, structure and function, and therapeutic implication of three of these adaptor oncogenes. CRKL. GAB2, and FRS2. Each of the three genes is recurrently amplified in lung adenocarcinoma or ovarian cancer, and is essential to cancer cell lines that harbor such amplification. Overexpression of each gene is able to transform immortalized human cell lines in in vitro or in vivo models. These observations identify adaptor protein as a distinct class of oncogenes and potential therapeutic targets.

Assessment of pathogenicity and functional characterization of APPL1 gene mutations in diabetic patients

BACKGROUND Adaptor protein,phosphotyrosine interacting with PH domain and leucine zipper 1(APPL1)plays a crucial role in regulating insulin signaling and glucose metabolism.Mutations in the APPL1 gene have been associated with the development of maturity-onset diabetes of the young type 14(MODY14).Currently,only two mutations[c.1655T>A(p.Leu552*)and c.281G>A p.(Asp94Asn)]have been identified in association with this disease.Given the limited understanding of MODY14,it is imperative to identify additional cases and carry out comprehensive research on MODY14 and APPL1 mutations.AIM To assess the pathogenicity of APPL1 gene mutations in diabetic patients and to characterize the functional role of the APPL1 domain.METHODS Patients exhibiting clinical signs and a medical history suggestive of MODY were screened for the study.Whole exome sequencing was performed on the patients as well as their family members.The pathogenicity of the identified APPL1 variants was predicted on the basis of bioinformatics analysis.In addition,the pathogenicity of the novel APPL1 variant was preliminarily evaluated through in vitro functional experiments.Finally,the impact of these variants on APPL1 protein expression and the insulin pathway were assessed,and the potential mechanism underlying the interaction between the APPL1 protein and the insulin receptor was further explored.RESULTS A total of five novel mutations were identified,including four missense mutations(Asp632Tyr,Arg633His,Arg532Gln,and Ile642Met)and one intronic mutation(1153-16A>T).Pathogenicity prediction analysis revealed that the Arg532Gln was pathogenic across all predictions.The Asp632Tyr and Arg633His variants also had pathogenicity based on MutationTaster.In addition,multiple alignment of amino acid sequences showed that the Arg532Gln,Asp632Tyr,and Arg633His variants were conserved across different species.Moreover,in in vitro functional experiments,both the c.1894G>T(at Asp632Tyr)and c.1595G>A(at Arg532Gln)mutations were found to downregulate the expression of APPL1 on both protein and mRNA levels,indicating their pathogenic nature.Therefore,based on the patient’s clinical and family history,combined with the results from bioinformatics analysis and functional experiment,the c.1894G>T(at Asp632Tyr)and c.1595G>A(at Arg532Gln)mutations were classified as pathogenic mutations.Importantly,all these mutations were located within the phosphotyrosinebinding domain of APPL1,which plays a critical role in the insulin sensitization effect.CONCLUSION This study provided new insights into the pathogenicity of APPL1 gene mutations in diabetes and revealed a potential target for the diagnosis and treatment of the disease.

Adaptor Protein Crk is Implicated in Mucus Formation in Mucinous Epithelial Ovarian Cancer (mEOC) Cells MCAS

Objective： The mucus production is an indicator for the histological grade of mucinous epithelial ovarian cancer （mEOC）. In our previous study, Crk expression was targeted in the human ovarian mucinous adenocarcinoma cell line MCAS through RNA interference, resulting in the establishment of Crk knock down cells. These cells exhibited decreased tumorigenic potential both in vitro and in vivo. The purpose of this study was to investigate if there is any change in the capability of forming mucus in these Crk knock down cells. Methods： Cytoplasmic periodic acid Schiff （PAS） staining and particle excluding assay were conducted to assess the mucus formation within and around cells, respectively. Additionally, the amount of mucus formed in tumor lumps from nude mice model was measured following HE and PAS staining. Results： The increased mucus production in Crk knockdown mEOC cells （MCAS） was manifested by increased number of enlarged cells filled with vacuoles-like mucus observed by phase-contrast microscope and cytoplasmic PAS staining; and enhanced mucus secretion was represented by the assembly of pericellular matrix in particle excluding assay and increased mucus area in tumor lumps from nude mice models. Conclusion： The course of carcinogenesis in mEOC is associated with the altered pattern of mucus production and secretion. The adaptor protein Crk is implicated in both pathways.

Arabidopsis adaptor protein 1G is critical for pollen development

Pollen development is a,pre-requisite for sexual reproduction of angiosperms, during which various cellular activities are involved. Pollen development accompanies dynamic remodeling of vacuoles through fission and fusion, disruption of which often compromises pollen viability. We previously reported that the Y subunit of adaptor protein 1 （AP1G） mediates synergid degeneration during pollen tube reception. Here, we demonstrate that AP1G is essential for pollen development. AP1G loss-of-function resulted in male gametophytic lethality due to defective pollen development. By ultrastructural analysis and fluorescence labeling, we demonstrate that AP1G loss-of-function compromised dynamic vacuolar remodeling during pollen development and impaired vacuolar acidification of pollen. Results presented here support a key role of vacuoles in gametophytic pollen development.

TRAF proteins as key regulators of plant development and stress responses

Tumor necrosis factor receptor-associated factor(TRAF)proteins are conserved in higher eukaryotes and play key roles in transducing cellular signals across different organelles.They are characterized by their C-terminal region(TRAF-C domain)containing seven to eight antiparallelβ-sheets,also known as the meprin and TRAF-C homology(MATH)domain.Over the past few decades,significant progress has been made toward understanding the diverse roles of TRAF proteins in mammals and plants.Compared to other eukaryotic species,the Arabidopsis thaliana and rice(Oryza sativa)genomes encode many more TRAF/MATH domaincontaining proteins;these plant proteins cluster into five classes:TRAF/MATH-only,MATH-BPM,MATH-UBP(ubiquitin protease),Seven in absentia(SINA),and MATH-Filament and MATHPEARLI-4 proteins,suggesting parallel evolution of TRAF proteins in plants.Increasing evidence now indicates that plant TRAF proteins form central signaling networks essential for multiple biological processes,such as vegetative and reproductive development,autophagosome formation,plant immunity,symbiosis,phytohormone signaling,and abiotic stress responses.Here,we summarize recent advances and highlight future prospects for understanding on the molecular mechanisms by which TRAF proteins act in plant development and stress responses.

Functions of the adaptor protein p66shc in solid tumors

p66she is a 66 kDa Src homology 2 domain containing （Shc） adaptor protein homolog. Previous studies have demonstrated that p66she is a proapoptotic protein involved in the cellular response to oxidative stress and in regulating mammalian lifespan. However, accumulating evidence also indicates its critical role in solid tumor progression. The expression of p66she varies in different types of solid tumors, and it can paradoxically promote as well as suppress tumor progression, survival, and metastasis, depending on the cellular context. In this review, we discuss its functions in various solid tumors, the mechanisms by which it mediates the process of anoikis （detachment-induced cell death）, and the epigenetic mechanisms that regulate its expression. These studies indicate the potential of p66she as a novel prognostic marker and therapeutic target for the prevention of tumor progression and metastasis.

Electroacupuncture relieves irritable bowel syndrome by increasing expression of nucleotide-binding oligomerization domain protein-like receptor family pyrin domain containing 6 in water-avoidance stress mice

OBJECTIVE: To investigate the effect of electroacupuncture(EA) on irritable bowel syndrome(IBS) in mice through regulating nucleotide-binding oligomerization domain protein-like receptor family pyrin domain containing 6(NLRP6).METHODS: Water-avoidance stress(WAS) mice model was used to investigate the effects and the mechanism of EA. Abdominal withdrawal reflex test, open field test, and intestinal motility test were used to evaluate visceral sensitivity, anxiety,and intestinal motility in mice. The expressions of NLRP6, Mucin-2(MUC2) and E-cadherin were determined using immunofluorescence and Western blotting assays.RESULTS: EA significantly upregulated the expression of NLRP6 in the intestine of mice. Moreover, EA increased the expressions of MUC2 and E-cadherin in WAS mice.CONCLUSION: Our study found that the relief of IBS symptoms by EA may involve the increase in the expression of NLRP6 in WAS mice.

Binding of bacterial secondary messenger molecule c di-GMP is a STING operation

Initial skirmishes between the host and pathogen result in spillage of the contents of the bacterial cell.Amongst the spillage,the secondary messenger molecule,cyclic dimeric guanosine monophosphate(c di-GMP),was recently shown to be bound by stimulator of interferon genes(STING).Binding of c di-GMP by STING activates the Tank Binding Kinase(TBK1)mediated signaling cascades that galvanize the body’s defenses for elimi-nation of the pathogen.In addition to c di-GMP,STING has also been shown to function in innate immune re-sponses against pathogen associated molecular pat-terns(PAMPs)originating from the DNA or RNA of pathogens.The pivotal role of STING in host defense is exemplified by the fact that STING-/-mice die upon infection by HSV-1.Thus,STING plays an essential role in innate immune responses against pathogens.This opens up an exciting possibility of targeting STING for development of adjuvant therapies to boost the im-mune defenses against invading microbes.Similarly,STING could be targeted for mitigating the inflamma-tory responses augmented by the innate immune sys-tem.This review summarizes and updates our current understanding of the role of STING in innate immune responses and discusses the future challenges in de-lineating the mechanism of STING-mediated responses.