Heterologous expression and function evaluation of Gloeobacter violaceus rhodopsin in Escherichia coli / 生物工程学报

Proton-pumping rhodopsin (PPR) is a simple photosystem widely distributed in nature. By binding to retinal, PPR can transfer protons from the cytoplasmic to the extracellular side of the membrane under illumination, creating a proton motive force (PMF) to synthesize ATP. The conversion of light into chemical energy by introducing rhodopsin into nonphotosynthetic engineered strains could contribute to promoting growth, increasing production and improving cell tolerance of microbial hosts. Gloeorhodopsin (GR) is a PPR from Gloeobacter violaceus PCC 7421. We expressed GR heterologously in Escherichia coli and verified its functional activity. GR could properly function as a light-driven proton pump and its absorption maximum was at 539 nm. We observed that GR was mainly located on the cell membrane and no inclusion body could be found. After increasing expression level by ribosome binding site optimization, intracellular ATP increased, suggesting that GR could supply additional energy to heterologous hosts under given conditions.

Genotypic and phenotypic analysis of RHO gene variants in a Chinese Han autosomal dominant retinitis pigmentosa family / 中华实验眼科杂志

Objective:To analyze the pathogenic genes and clinical phenotypes of a Chinese Han family with autosomal dominant retinitis pigmentosa (ADRP).Methods:A pedigree investigation study was conducted, and a Chinese Han RP family that underwent genetic counseling in the Henan Provincial People's Hospital in November 2019 was collected.Twenty members of this family from 4 generations, including 9 patients and 11 phenotypically normal individuals, were enrolled.Visual acuity, peripheral visual field test and fundus examination were performed on some family members.Peripheral blood samples were collected from the family members, and DNA was extracted.Exon-targeted sequencing containing 43 genes associated with RP was performed on the proband using the Ion Torrent PGM sequencing platform.The mutations were verified by polymerase chain reaction and Sanger sequencing.Online software was applied to predict the protein function of the variant.The amino acid sequences of the variant loci were compared using the ClustalW2 multiplex alignment program.The pathogenicity of the variant was analyzed according to American College of Medical Genetics and Genomics (ACMG) criteria and guidelines for classification of genetic variant.This study adhered to the Declaration of Helsinki.The study protocol was approved by an Ethics Committee of Henan Provincial People's Hospital (No.HNEECKY-2019[15]).Results:The family was consistent with autosomal dominant inheritance.The proband, a 26-year-old male, had bilateral night blindness since childhood, with visual acuity of 0.25 in the right eye and 0.5 in the left eye.There was osteoblast-like pigmentation in his both retinas, thinned retinal vessels and pale optic disc.Full-field electroretinogram examination showed reduced scotopic a- and b-wave peaks and severely reduced photopic a- and b-wave peaks.The rest of the family began to develop night blindness when 7 to 10 years old, having complete loss of peripheral vision around 50 years of age, and typical RP changes were found in ophthalmic examination.Genetic testing revealed a heterozygous missense variant c. 982delC (p.L328fs) in exon 5 of the family's rhodopsin ( RHO) gene (NM_000539.3). This variant resulted in the change of 21 amino acids after amino acid 328 in the encoded RHO protein, increasing amino acids in the coding region from 348 to 358 and altering the structure of the RHO protein.The analysis of protein homology sequence alignment between several different species showed that the locus was highly conserved.According to the guidelines of the ACMG criteria and guidelines for classification of genetic variants, the variant was a pathogenic mutation because there were six evidences including one very strong evidence of pathogenicity PVS1, two moderate evidences of pathogenicity PM2 and three supporting evidences of pathogenicity, PP1, PP3 and PP4. Conclusions:The c. 982delC variant in the RHO gene is a pathogenic mutation in this pedigree, and this variant is reported for the first time in a Chinese Han family.

Human bone marrow-derived mesenchymal stem cells differentiate into retinal cells in vitro / 中国药理学通报

Aim To study the differentiation of human bone marrow-derived mesenchymal stem cells ( HM-SCs) into retinal cells in vitro. Methods HMSCs were isolated from human bone marrow after Ficoll den-sity gradient centrifugation. The adherent cells after at least 5 passages were used for study. Immunopheno-type of the cells was analysed by flow cytometer, and cellular differentiation was identified by immunofluores-cence labeling technique. Results The target cells derived from human bone marrow adhered to the plate with fibroblastic-like morphology, whose surface mark-ers were similar to mesenchymal stem cells. Major cells were positive for CD90 , CD44 , CD147 , while they were all negative for CD34, CD45, HLA-DR. In the differentiation study, HMSCs cultured in induced me-dium can differentiate into nestin ( neural stem cell ) -positive cell, GFAP ( glial fibrillary acidic protein ) -positive glial cells and retina-specific neurons express-ing Rhodopsin with CD90 ( mesenchymal stem cells )-negative. Conclusion HMSCs have the ability to dif-ferentiate into retinal neural cells in vitro.

Induce and differenctiation of marrow mesenchymal stem cell into photoreceptor-like cell in vitro and microenvironment / 中华实验眼科杂志

Background Marrow mesenchymal stem cells (MSCs) has been successful induced to differentiate into corneal cells,retinal ganglion cells (RGCs) and retinal neuron-like cells in recent years,but there are few studies about MSCs induced into photoreceptor cells and their microenvironment.Objective The aim of this study was to explore the induce and differentiation of bone marrow mesenchymal stem cells (BMSCs) into photoreceptor-like cells in vitro and microenvironment.Methods The second generation of human BMSCs strain and RPE cells strain were cultured and passaged,respectively,and the fourth generation of BMSCs and the third generation of RPE cells were used in the experiment.BMSCs were cocultured using the mesenchymal stem cells medium (MSCM) contained 20 μg/L basic fibroblast growth factor (bFGF),20 μg/L epithelial growth factor (EGF)and 20 μg/L brain derived neurotrophic factor (BDNF) with RPE cells to induce the differentiation of BMSCs in the induced group,and BMSCs were cultured in MSCM only in the control group.The morphology of induced and differentiated cells were observed under the inverted microscope.Inmmunocytochemistry was used in induced for 3-,5-,7-day cells to detect the expression rate of rhodopsin protein for the identification of phenotype of the differentiated cells.RT-PCR was used in induced for 5-,7-day cells to detect the expressions of rhodopsin mRNA and recoverin mRNA.Results Cultured BMSCs grew well with the spindle shape,and passaged RPE cells showed the uniform size and polygon shape with the abundant pigment in the cells.Some induced cells appeared to be the neuron-like cells with round shape and long prominence and the secondary reticular branches.The expression rates of rhodopsinin the cells were (5.83±0.29)％,(20.36±0.32)％ and (29.80±2.30)％ in the third,fifth and seventh day after induce,which were significantly higher than (0.71 ±0.35) ％,(2.56±0.24) ％ and (2.32±0.42) ％ of control cells (t3 d =41.510,t5d =107.290,t7 d =30.036,P＜0.01).The grey scales of rhodopsin mRNA and recoverin mRNA were significantly elevated in the induced and differentiated cells compared with control cells in the fifth and seventh day (rhodopsin mRNA:t5 d =103.506,t7 d =122.584,P＜0.01 ; recoverin mRNA:t5 d =106.674,t7 d =189.992,P＜0.01).Conclusions BMSCs can be successfully induced to differentiate into photoreceptor cells after cocultured by conditioned medium with RPE cells.

Detection and analysis of the Rhodopsin gene in a consanguineous Chinese Han autosomal dominant retinitis pigmentosa family / 中华实验眼科杂志

Background Rhodopsin (RHO) gene is the most common disease gene for autosomal dominant retinitis pigmentosa (adRP),one of the main pathogenesis is that misfolded mutant RHO proteins accumulate in the endoplasmic reticulum and cause endoplasmic reticulum stress (ERS).Objective This study aimed to determine the genetic basis for a consanguineous Chinese Han adRP family.Methods This study procedure complied with Helsinki Declaration.All participants in the family were investigated under the informed consent.Regular ocular examination was performed on the patients in this family.Next-generation sequencing (NGS) was carried out to screen the mutations in 189 genes associated with hereditary retinal diseases (HRDs).After being analyzed and filtered,variations detected by NGS were validated by Sanger sequencing and evaluating of pathogenicity.The wild-type RHOWT and mutant RHOP53Rwere cloned into the vector pEGFP-N1.Then the two plasmids were transfected into adult retinal pigmentosa epithelium cell line(ARPE19) and human embryo kidney 293 line (HEK293) to observe the location of rhodopsin-GFP fusion protein in cells,and the expression of ERS related protein XBP1 in the cells was detected by quantitative-PCR and Western blot.Results This family included 5 generations with the typical adRP characteristics.Genetic analysis identified a heterozygous variation,p.P53R in RHO gene,which was fully cosegregated in the family.Wild-type RHOWT-GFP fusion proteins showed the green fluorescence on the endoplasmic reticulum and cytomembrane,but the misfolded mutant RHO-GFP fusion protein gathered only in endoplasmic reticulum.Compared to wild-type RHOWT,the XBP1 was activated and increased by (1.28 ±0.09) fold.The introns of 26 bases in XBP1 mRNA were removed in the HEK293 cells with mutant RHO-GFP fusion protein,and the expression of XBP1 was stronger in the HEK293 cells with mutant RHO-GFP than that in HEK293 cells with wild type RHO-GFP and cells with blank pEGFP-N1 plasmid.Conclusions Heterozygous variant RHO p.P53R is very likely the pathogenical mutation in the adRP family.The RHOP53R mutant rhodopsin protein can not be delivery effectively from the endoplasmic reticulum to the cell membrane,and these proteins accumulate in the endoplasmic reticulum,which causes ERS.

Linkage analysis and mutation screening of candidate gene in a Han Nationality family with autosomal dominant retinitis pigmentosa / 中华实验眼科杂志

BackgroundRetinitis pigmentosa (RP) has the genetic and phenotype heterogeneity.To determine the disease-causing gene is a foundation of gene therapy.Objective This study was to localize the pathogenic gene and screen the gene mutation associated with Han Nationality autosomal dominant retinitis pigmentosa (ADRP) in a Chinese family.MethodsTwenty-one families enrolled this study,including 12 patients with ADRP and 9 individuals with normal phenotype.Perimetry,fundus examination,electrooculogram ( EOG ) and electroretinogram (ERG) were performed in 12 patients.Genetic linkage analysis was performed on the subjects in all known genetic loci related to ADRP with a panel of microsatellite markers.Subsequently,the mutation screening of rhodopsin gene was screened by direct DNA sequencing.This study was approved by Ethic Committee of Zhongnan Hospital of Wuhan University.Informed consent was obtained from each subject.ResultsThe fundus appearance of the proband was in accordance with the ADRP,and the EOG and ERG showed undetectable.Contractive visual field also was exhibited in the proband.Linkage analysis showed that the maximum logarithm of the odds(LOD) score reached 3.6671 at marker D3S1292 at recombination fraction θ =0.0.The results of direct DNA sequencing revealed a C→ G transversion mutation at codon 53 in exon 1 of rhodopsin gene,which resulted in a proline to arginine change (Pro53Arg) in 12 patients.However,no similar mutation was found in the unaffected members of this family.ConclusionsThe missence mutation Pro53Arg in rhodopsin gene cosegregate with the RP disease.It is determined to be a pathogenic factor of this ADRP family.

Modulation of rhodopsin gene expression and signaling mechanisms evoked by endothelins in goldfish and murine pigment cell lines

Endothelins (ETs) and sarafotoxins (SRTXs) belong to a family of vasoconstrictor peptides, which regulate pigment migration and/or production in vertebrate pigment cells. The teleost Carassius auratus erythrophoroma cell line, GEM-81, and Mus musculus B16 melanocytes express rhodopsin, as well as the ET receptors, ETB and ETA, respectively. Both cell lines are photoresponsive, and respond to light with a decreased proliferation rate. For B16, the doubling time of cells kept in 14-h light (14L):10-h darkness (10D) was higher compared to 10L:14D, or to DD. The doubling time of cells kept in 10L:14D was also higher compared to DD. Using real-time PCR, we demonstrated that SRTX S6c (12-h treatment, 100 pM and 1 nM; 24-h treatment, 1 nM) and ET-1 (12-h treatment, 10 and 100 pM; 24- and 48-h treatments, 100 pM) increased rhodopsin mRNA levels in GEM-81 and B16 cells, respectively. This modulation involves protein kinase C (PKC) and the mitogen-activated protein kinase cascade in GEM-81 cells, and phospholipase C, Ca2+, calmodulin, a Ca2+/calmodulin-dependent kinase, and PKC in B16 cells. Cells were kept under constant darkness throughout the gene expression experiments. These results show that rhodopsin mRNA levels can be modulated by SRTXs/ETs in vertebrate pigment cells. It is possible that SRTX S6c binding to the ETB receptors in GEM-81 cells, and ET-1 binding to ETA receptors in B16 melanocytes, although activating diverse intracellular signaling mechanisms, mobilize transcription factors such as c-Fos, c-Jun, c-Myc, and neural retina leucine zipper protein. These activated transcription factors may be involved in the positive regulation of rhodopsin mRNA levels in these cell lines.

The effects of varied antigen retrieval methods on immunohistochemistry of functional proteins in retinal paraffin section / 眼科研究

Background Antigen retrieval method is the key of improving the successful rate of immunohistochemical assay in paraffin sections.To study an available method of antigen retrieval is a goal to achieve both good immunochemistry result and preserving retinal proteins.ObjectiveThe aim of present study is to investigate tyrosin digestion,high-temperature heat pressure,water bath heating and microwave repair in antigen retrieval for retinal tissues.MethodsRetinal tissue was isolated and obtained from clean Chinchilla rabbits.Four hundreds retinal paraffin sections were prepared.Four kinds of antigen retrieval methods for retinal tissue including tyrosin digestion,high-temperature heat pressure,water bath heating and microwave repair were used respectively.The depigmentated retinal paraffin section without antigen retrieval was used as control.The positive rates of expression of CRALBP,Rhodopsin and opsin proteins were evaluated and compared among four kinds of antigen retrieval methods by immunochemistry.ResultsCRALBP,Rhodopsin and opsin protein was positively expressed in cytoplasm of retinal pigment epithelial cells and the outer segment of photoreceptor respectively.No significant difference was found in the positive expression rates of these three proteins among four kinds of antigen retrieval methods (P＞0.05),but the differences in tissue integrity and background staining were statistically significant (P＜0.01).The structural damage of retina included loss and pucker of scalera,crack of nucleus and abnormal background stain in high-temperature heat pressure method,water bath heating method and microwave retrieval method.However,stable CRALBP,Rhodopsin and opsin protein expression and strain effectiveness,clear background without unspecific staining and integrated tissue were seen in tyrosin digestion method.ConclusionDuring the clinical pathology analysis of retinal tissue,the application of tyrosin digestion in antigen retrieval could obtain a better effectiveness.

Family A G-Protein coupled receptors: an overview of structure-function relationships

Family A G-protein coupled receptors (AGPCRs) form the largest group of correlate receptors whose structure, a bundle of seven-trans-membrane (7 TM) helices, may be activated thus becoming able to transduce a signal from the extracellular medium to the cytosol. This activation may be constitutional, for instance due to permanent structural modifications, or be physiologically triggered by agonist binding at an external and accessible specific site. Based on thestructures of agonists, AGPCRs may be divided according to pharmacological assays into many classes of receptors, each one comprising many types or sub-types of proteins, as differentiated by specific binding of inhibitors, all of them performing a multitude of functions. It is noteworthy that AGPCRs have been more recently cloned and their sequences of amino acids determined in a large scale, a condition that has allowed these receptors to be sorted by a new criterium. Sequence analyses have consistently matched functional assays for classification of AGPCRs except for a certain number of functionally unknown receptors which have been cataloged as orphan receptors. A colossal number of AGPCRs, more than 10,000 sequences belonging to more than 1,000 different types of receptors, may nowadays be multiply-aligned what has been enabling the determination of parameters of residue conservation and characterization of special motifs along the structure of these proteins. There are at the present time, high-resolution 3D structures for the following AGPCRs: inactive rhodopsin, retinal-free opsin, Beta adrenoceptor and adenosine receptors. Among them, hodopsin structures are reliable enough to be used as prototypes for analyses of residue conservation and mechanisms of activation of receptors, specially at the level of the more conserved structure in the cytosolic half of their 7TM bundle.

Analysis of the mutation of rhodopsin gene in an inbreeding family with autosomal recessive retinitis pigmentosa / 中华眼底病杂志

Objective To detect characteristics and the pathogenesis of rhodopsin (RHO) gene mutation in an inbreeding family with autosomal recessive retinitis pigmentosa (ARRP). Methods Peripheral venous blood 5-8 ml was abstracted from 8 members in the inbreeding ARRP family and 10 control individuals. DNA gene group was picked. Extron 1-5 of RHO gene was amplified by polymerase chain reaction (PCR),and the mutation of RHO gene was screened by direct DNA sequence measurement. Results The Gln-344-Arg mutation in the RHO gene was detected in 3 patients with ARRP and homozygotes of the mutation in 3 patients were found. Heterozygous of the mutation was detected in the parent of patients and 1 healthy family member. No mutation of RHO gene was found in 2 healthy family members and 10 control individuals. Conclusions The Gln-344-Arg mutation in the RHO gene may be the pathogenic factor of the ARRP family; the frequency of the mutation of RHO gene may increase in the inbreeding ARRP family.

Analysis of the mutations of rhodopsin gene in autosomal dominant retinitis pigmentosa family / 中华眼底病杂志

Objective To detect and analyse the mutations in rhodopsin gene of members in a family affected by autosomal dominant retinitis pigmentosa (ADRP). Methods Using the polymerase chain reaction (PCR), we amplified exon 1-5 of rhodopsin gene in patients with ADRP,and analyzed it with direct sequence measuement. Results The Gly-182-Asp mutation in the rhodopsin gene was detected in most of affected members of this ADRP family, but no mutation was detected in two affected members and the control ones. Conclusion We cannot regard the Gly-182-Asp mutation in the rhodopsin gene as the pathagenic factor of the ADRP family. It is likely there is a new gene next to the rhodopsin gene.