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.

Binding of Human SWI1 ARID Domain to DNA without Sequence Specificity: A Molecular Dynamics Study

SWI 1 is a member of a new class of tumor DNA-binding proteins named as the AT-rich in- teraction domain family （ARID）, and considered to bind with AT base pairs specifically. Genomic and functional data support ARID1A as a tumor suppressor because AR1D1A/BAF250a （SWI1） subunit of the SWI/SNF chromatin-remodeling complex has emerged as recurrently mutated in a broad array of tumor types. But the crystal structure of SWI1 has not been solved as yet. Using docking and molecular dynamics, we predicted the DNA interaction pattern of human SWI1 ARID and made comparisons with the other two representative ARID family members, human Mrf-2 ARID and Drosophila Dri ARID. Dynamic results revealed that the N-terminal and loop L1 of SWI1 ARID bound with the DNA major groove, while the loop L2 and helix H6 bound with the minor groove. Moreover, it was found that SWI1 ARID bound with DNA apparently in a sequence-nonspecific manner. It was concluded that SWI1 ARID can form stable complex with sequence-nonspecific DNA segment comparing to Mrf-2 ARID/DNA and Dri ARID/DNA sequence-specific complexes.

Clinicopathologic and prognostic relevance of ARID1A protein loss in colorectal cancer

AIM: To explore the association between AT-rich interactive domain 1A (ARID1A) protein loss by immunohistochemistry and both clinicopathologic characteristics and prognosis in patients with colorectal cancer.

Interaction of the major inflammatory bowel disease susceptibility alleles in Crohn’s disease patients

AIM:To investigate the interaction of interleukin-23 receptor(IL23R)(rs1004819 and rs2201841),autophagy-related 16-like 1(ATG16L1)(rs2241880), caspase recruitment domain-containing protein 15 (CARD15)genes,and IBD5 locus in Crohn's disease(CD) patients. METHODS:A total of 315 unrelated subjects with CD and 314 healthy controls were genotyped.Interactions and specific genotype combinations of a total of eight variants were tested.The variants of IBD5locus(IGR2198a_1 rs11739135 and IGR2096a_1 rs12521868),CARD15(R702W rs2066845 and L1007fs rs2066847),ATG16L1(rs2241880)and IL23R (rs1004819,rs2201841)genes were genotyped by PCR-RFLP,the G908R(rs2066844)in CARD15 was determined by direct sequencing. RESULTS:The association of ATG16L1 T300A with CD was confirmed[P=0.004,odds ratio(OR)=1.69, 95%CI:1.19-2.41],and both IL23R variants were found to represent significant risk for the disease(P= 0.008,OR=2.05,95%CI:1.20-3.50 for rs1004819 AA;P<0.001,OR=2.97,95%CI:1.65-5.33 for rs2201841 CC).Logistic regression analysis of pairwise interaction of the inflammatory bowel disease (IBD)loci indicated that IL23R,ATG16L1,CARD15 and IBD5(IGR2198a_1)contribute independently to disease risk.We also analysed the specific combina- tions by pair of individual ATG16L1,IL23R rs1004819, rs2201841,IGR2198a_1,IGR2096a_1 and CARD15 genotypes for disease risk influence.In almost all cases,the combined risk of susceptibility pairs was higher in patients carrying two different risk-associated gene variants together than individuals with just one polymorphism.The highest OR was found for IL23R rs2201841 homozygous genotype with combination of positive CARD15 status(P<0.001,OR=9.15,95% CI:2.05-40.74). CONCLUSION:The present study suggests a cumulative effect of individual IBD susceptibility loci.

ARID1A Inactivation Increases Expression of circ0008399 and Promotes Cisplatin Resistance in Bladder Cancer

Objective Cisplatin(CDDP)-based chemotherapy is a first-line,drug regimen for muscle-invasive bladder cancer(BC)and metastatic bladder cancer.Clinically,resistance to CDDP restricts the clinical benefit of some bladder cancer patients.AT-rich interaction domain 1A(ARID1A)gene mutation occurs frequently in bladder cancer;however,the role of CDDP sensitivity in BC has not been studied.Methods We established ARID1A knockout BC cell lines using CRISPR/Cas9 technology.IC50 determination,flow cytometry analysis of apoptosis,and tumor xenograft assays were performed to verify changes in the CDDP sensitivity of BC cells losing ARID1A.qRT-PCR,Western blotting,RNA interference,bioinformatic analysis,and ChIP-qPCR analysis were performed to further explore the potential mechanism of ARID1A inactivation in CDDP sensitivity in BC.Results It was found that ARID1A inactivation was associated with CDDP resistance in BC cells.Mechanically,loss of ARID1A promoted the expression of eukaryotic translation initiation factor 4A3(EIF4A3)through epigenetic regulation.Increased expression of EIF4A3 promoted the expression of hsa_circ_0008399(circ0008399),a novel circular RNA(circRNA)identified in our previous study,which,to some extent,showed that ARID1A deletion caused CDDP resistance through the inhibitory effect of circ0008399 on the apoptosis of BC cells.Importantly,EIF4A3-IN-2 specifically inhibited the activity of EIF4A3 to reduce circ0008399 production and restored the sensitivity of ARID1A inactivated BC cells to CDDP.Conclusion Our research deepens the understanding of the mechanisms of CDDP resistance in BC and elucidates a potential strategy to improve the efficacy of CDDP in BC patients with ARID1A deletion through combination therapy targeting EIF4A3.

沉默CITED1基因对甲状腺乳头状癌K1细胞生物学特性的影响

目的:探讨沉默CITED1(Cbp/p300 interacting transactivator with Glu/Asp rich carboxy-terminal domain 1)基因表达对甲状腺乳头状癌K1细胞增殖、凋亡和迁移等生物学行为的影响。方法:将携带特异性靶向CITED1基因的shRNA(CITED1-shRNA)及其阴性对照shRNA(negative control-shRNA,NC-shRNA)的重组慢病毒分别感染甲状腺乳头状癌K1细胞株,采用实时荧光定量PCR法和蛋白质印迹法检测CITED1基因沉默效率;然后采用CCK-8法检测细胞增殖,FCM法检测细胞周期和细胞凋亡,划痕愈合实验检测细胞迁移能力。结果:经携带CITED1-shRNA的重组慢病毒感染后,甲状腺乳头状癌K1细胞中CITED1 mRNA和蛋白的表达水平均明显降低(P值均<0.01),证明成功获得了CITED1基因沉默的K1细胞株。沉默CITED1基因表达后,K1细胞的增殖能力明显降低(P <0.01),细胞凋亡率明显升高(P=0.001),G0/G1期细胞所占比例明显增高(P=0.007),G2/M及S期细胞所占比例均明显降低(P值均<0.05),而且12 h和24 h时细胞迁移能力明显减弱(P值均<0.01)。结论:沉默CITED1基因表达可以抑制甲状腺乳头状癌K1细胞的增殖和迁移,促进肿瘤细胞凋亡。