An exon skipping in a SEPALLATA-Like gene is associated with perturbed floral and fruits development in cucumber

Summary We isolated a mutant showing perturbations in the development of male and female floral organs and fruits. Analysis of the single nucleotide polyTnorphisms from bulked F2 pools identified the causative variant occurring in Csa4G126690. Csa4G126690 shows high homol- ogy to Arobidopsis 5EPALLATA2 （SEP2） thus being desig- nated CsSEP2. The causative variant was located on the splicing site of CsSEP2, resulting in the skipping of exon 6 and abolishment of the transcriptional activity. Our data suggest that CsSEP2 is involved in the floral organ and fruits development by conferring transcriptional activity.

CRISPR/Cas9-mediated NlInR2 mutants:Analyses of residual mRNA and truncated proteins

CRISPR/Cas9 technology is a powerful genome manipulation tool in insects.However,little is known about whether mRNA and protein of a target gene are completely cleared in homozygous mutants.This study generated homozygous mutants of the insulin receptor gene 2(NlInR2)in the brown planthopper(Nilaparvata lugens)using CRISPR/Cas9 genome editing.Both frameshift mutants,E5_D17 and E6_I7,differentiated towards long wings,but there were differences in wing morphology,with E5_D17 showing wing deformities.Subsequent investigations revealed the presence of residual expression of NlInR2 mRNA in both mutants,as well as the occurrence of spliceosomes featuring exon skipping splicing in E5_D17.Additionally,the E5_D17 exhibited the detection of N-terminally truncated NlInR2 protein.RNA interference experiments indicated that the knockdown of NlInR2 expression in the E5_D17 mutant line increased the proportion of wing deformities from 11.1 to 65.6%,suggesting that the residual NlInR2 mRNA of the E5_D17 mutant might have retained some genetic functions.Our results imply that systematic characterization of residual protein expression or function in CRISPR/Cas9-generated mutant lines is necessary for phenotypic interpretation.

Stem cell transplantation for treating Duchenne muscular dystrophy A Web of Science-based literature analysis

OBJECTIVE： To identify global research trends in stem cell transplantation for treating Duchenne muscular dystrophy using a bibliometric analysis of Web of Science. DATA RETRIEVAL： We performed a bibliometric analysis of studies on stem cell transplantation for treating Duchenne muscular dystrophy from 2002 to 2011 retrieved from Web of Science. SELECTION CRITERIA： Inclusion criteria： （a） peer-reviewed published articles on stem cell transplantation for treating Duchenne muscular dystrophy indexed in Web of Science; （b） original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items; and （c） publication between 2002 and 2011. Exclusion criteria： （a） articles that required manual searching or telephone access; （b） documents that were not published in the public domain; and （c） corrected papers. MAIN OUTCOME MEASURES： （1）Annual publication output; （2） distribution according to subject areas; （3） distribution according to journals; （4） distribution according to country; （5） distribution according to institution; （6） distribution according to institution in China; （7） distribution according to institution that cooperated with Chinese institutions; （8） top-cited articles from 2002 to 2006; （9） top-cited articles from 2007 to 2011. RESULTS： A total of 318 publications on stem cell transplantation for treating Duchenne muscular dystrophy were retrieved from Web of Science from 2002 to 2011, of which almost half derived from American authors and institutes. The number of publications has gradually increased over the past 10 years. Most papers appeared in journals with a focus on gene and molecular research, such as Molecular Therapy, Neuromuscular Disorders, and PLoS One. The 10 most-cited papers from 2002 to 2006 were mostly about different kinds of stem cell transplantation for muscle regeneration, while the 10 most-cited papers from 2007 to 2011 were mostly about new techniques of stem cell transplantation for treating Duchenne muscular dystrophy. CONCLUSION： The publications on stem cell transplantation for treating Duchenne muscular dystrophy were relatively few. It also needs more research to confirm that stem cell therapy is a reliable treatment for Duchenne muscular dystrophy.

Physiological and druggable skipping of immunoglobulin variable exons in plasma cells

The error-prone V(D)J recombination process generates considerable amounts of nonproductive immunoglobulin(Ig)pre-mRNAs.We recently demonstrated that aberrant Ig chains lacking variable(V)domains can be produced after nonsense-associated altered splicing(NAS)events.Remarkably,the expression of these truncated Ig polypeptides heightens endoplasmic reticulum stress and shortens plasma cell(PC)lifespan.Many questions remain regarding the molecular mechanisms underlying this new truncated Ig exclusion(TIE-)checkpoint and its restriction to the ultimate stage of B-cell differentiation.To address these issues,we evaluated the extent of NAS of Ig pre-mRNAs using an Ig heavy chain(IgH)knock-in model that allows for uncoupling of V exon skipping from TIE-induced apoptosis.We found high levels of V exon skipping in PCs compared with B cells,and this skipping was correlated with a biallelic boost in IgH transcription during PC differentiation.Chromatin analysis further revealed that the skipped V exon turned into a pseudo-intron.Finally,we showed that hypertranscription of Ig genes facilitated V exon skipping upon passive administration of splice-switching antisense oligonucleotides(ASOs).Thus,V exon skipping is coupled to transcription and increases as PC differentiation proceeds,likely explaining the late occurrence of the TIE-checkpoint and opening new avenues for ASO-mediated strategies in PC disorders.

Temporal regulation of alternative splicing events in rice memory under drought stress

Plant adaptation to drought stress is essential for plant survival and crop yield.Recently,harnessing drought memory,which is induced by repeated stress and recovery cycles,was suggested as a means to improve drought resistance at the transcriptional level.However,the genetic mechanism underlying drought memory is unclear.Here,we carried out a quantitative analysis of alternative splicing(AS)events in rice memory under drought stress,generating 12 transcriptome datasets.Notably,we identified exon skipping(ES)as the predominant AS type(>80%)in differential alternative splicing(DAS)in response to drought stress.Applying our analysis pipeline to investigate DAS events following drought stress in six other plant species revealed variable ES frequencies ranging from 9.94%to 60.70%depending on the species,suggesting that the relative frequency of DAS types in plants is likely to be speciesspecific.The dinucleotide sequence at AS splice sites in rice following drought stress was preferentially GC-AG and AT-AC.Since U12-type splicing uses the AFAC site,this suggests that drought stress may increase U12-type splicing,and thus increase ES frequency.We hypothesize that multiple isofbrms derived from exon skipping may be induced by drought stress in rice.We also identified 20 transcription factors and three highly connected hub genes with potential roles in drought memory that may be good targets for plant breeding.

Activity and bioavailability of tepotinib for leptomeningeal metastasis of NSCLC with MET exon 14 skipping mutation

Tepotinib is a key drug for cancer patients with mesenchymal-epithelial transition receptor tyrosine kinase proto-oncogene(MET)exon 14 skipping mutation.However,its bioavailability in the cerebrospinal fluid(CSF)in humans has not been fully elucidated.Moreover,information about the efficacy of tepotinib in patients with leptomeningeal metastasis is limited.Here,we present the case of a 56-year-old man who was diagnosed with lung adenocarcinoma with MET exon 14 skipping mutation.He was urgently hospitalized due to leptomeningeal metastasis.We administered tepotinib 500 mg/day as the second-line therapy and observed improvement in leptomeningeal metastasis and performance status.The tepotinib concentrations reached 1,648 ng/mL in the plasma and 30.6 ng/mL in the CSF,with a penetration rate(CSF/plasma)of 1.83%.These demonstrate tepotinib could achieve a high rate of central nervous system transition and could be effective against leptomeningeal metastasis.

Identification of compound heterozygous mutations in the ITGA2B gene in a Chinese patient with Glanzmann thrombasthenia

Background Glanzmann thrombasthenia （GT） is an autosomal recessive bleeding disorder characterized by the tendency to hemorrhage and the inability of platelets to aggregate in response to agonists. GT is caused by a defect of the platelet glycoprotein lib/Ilia complex. The objective of this study was to describe the clinical features and the genetic cause of GT in a 6-year-old girl from south China. Methods A three-generation family was studied. The proband patient aged 6 years and her parents undertook examinations of platelet counts, blood film, bleeding time, platelet aggregation, and flow cytometry. All coding exons of the ITGA2B and ITGB3 genes were amplified by polymerase chain reaction （PCR）, and direct sequencing was performed for mutational screening on the patient and normal controls consisted of 52 healthy blood donors. Reverse transcription PCR was conducted to test for exon skipping. Results The proposita patient showed dispersing platelets, prolonged bleeding time, and severely reduced platelet aggregation in response to the physiological agonists adenosine diphosphate （ADP）, epinephrine, collagen, and ristocetin. Flow cytometric measurements showed that the contents of allb and 133 were significantly decreased. Sequencing results demonstrated two different types of heterozygous mutations existed in the allb gene （c.2930delG and IVS15-1delG）. The compound mutations were also confirmed in the patient＇s mother and father separately. Conclusions The allbβ3 deficiency of the proband was caused by two compound ITGA2B mutations, which were first reported in Chinese GT patients. The IVS15-1delG was first confirmed to cause an exon skipping.

Gene editing:A new step and a new direction toward finding a cure for Duchenne muscular dystrophy(DMD)

Duchenne muscular dystrophy(DMD)is a progressive muscle degenerative disease affecting one out of 3500 male births.Patients usually succumb to the disease by age 25.It has been shown that skipping exons of the DMD gene that contain disease-causing mutations from the pre-mRNA can result in a shortened,but functional,dystrophin protein that could bring clinical benefits to patients.A recent breakthrough has been reported in Science by three groups who demonstrated that genetically deleting exon 23 by gene editing can restore the expression of dystrophin(albeit a shortened version)and improve the muscle function in a mouse model of DMD.