Paired Box Gene 6 Research Articles

A positive feedback inhibition of isocitrate dehydrogenase 3β on paired-box gene 6 promotes Alzheimer-like pathology

Impaired brain glucose metabolism is an early indicator of Alzheimer’s disease (AD); however, the fundamental mechanism is unknown. In this study, we found a substantial decline in isocitrate dehydrogenase 3β (IDH3β) levels, a critical tricarboxylic acid cycle enzyme, in AD patients and AD-transgenic mice’s brains. Further investigations demonstrated that the knockdown of IDH3β induced oxidation-phosphorylation uncoupling, leading to reduced energy metabolism and lactate accumulation. The resulting increased lactate, a source of lactyl, was found to promote histone lactylation, thereby enhancing the expression of paired-box gene 6 (PAX6). As an inhibitory transcription factor of IDH3β, the elevated PAX6 in turn inhibited the expression of IDH3β, leading to tau hyperphosphorylation, synapse impairment, and learning and memory deficits resembling those seen in AD. In AD-transgenic mice, upregulating IDH3β and downregulating PAX6 were found to improve cognitive functioning and reverse AD-like pathologies. Collectively, our data suggest that impaired oxidative phosphorylation accelerates AD progression via a positive feedback inhibition loop of IDH3β-lactate-PAX6-IDH3β. Breaking this loop by upregulating IDH3β or downregulating PAX6 attenuates AD neurodegeneration and cognitive impairments.

Familial Congenital Aniridia with Subluxated Lens and Glaucoma

Introduction: Congenital aniridia is a bilateral iris aplasia or hypoplasia associated with other ocular disorders. The purpose of this case report is to describe the clinical manifestation of congenital aniridia in two members of one family. Case Presentation: The first patient (mother) is a 43-year-old and the second patient (daughter) is a 12-year-old. Both patients complained of blurred vision since childhood. The visual acuity of the first patient was a positive light perception on the right eye (RE) and no light perception on the left eye (LE); the visual acuity of the second patient was 1/60 on the RE and 3/32 on the LE. Both patients had horizontal nystagmus and increased intraocular pressure (IOP) (N+1 palpation) in both eyes. Anterior segment abnormalities of both patients include aniridia with iris rudimentary and superiorly subluxated lens. The first patient also had LE corneal leukoma and RE cataract. The second patient also had right and left eye corneal conjunctivalization. Fundus examination showed no fundus reflex on the first patient and tigroid retina with foveal hypoplasia on the second patient. Eye ultrasounds of both patients showed vitreous opacity. Conclusions: Congenital aniridia primarily originates from a mutation in the paired box gene-6 (PAX6) and is associated with other ocular anomalies such as nystagmus, amblyopia, keratopathies, cataract, lens luxation, glaucoma, fovea, optic nerve hypoplasia. Patients in this case showed similar conditions between mother and daughter, however, the mother's condition was more advanced and more degenerated than the daughter's condition.

Mechanism of PAX6 overexpression in inhibiting the growth of hepatocellular carcinoma cells and promoting the killing ability of the natural killer cells.

Paired box gene 6 (PAX6) plays a major role in the regulation of embryonic development. Abnormal expression of PAX6 is associated with the development of various tumors. PAX6 can play a role in promoting or suppressing cancer in different tumors. This study aim to observe the effect of overexpression of PAX6 on the growth of hepatocellular carcinoma cells, and the killing of hepatocellular carcinoma cells via natural killer (NK) cell and the possible mechanism. The protein levels of PAX6, soluble major histocompatibility complex class I-like protein A (sMICA) and soluble UL16 binding protein 2 (sULBP2) in peripheral blood from 68 cases of hepatocellular carcinoma (HCC) patients and 10 healthy volunteers were detected by ELISA. Hepatocellular carcinoma cell line (HepG2, LM3) and human normal liver cells (LO2) were cultured at 37 ℃ and 5% CO2 condition in vitro. The PAX6 overexpressed plasmid (PAX6-OE) and empty vector (NC) were transferred into HepG2 and LM3 cells to construct stable cell lines. The mRNA and protein expression levels of PAX6 in HepG2 and LM3 cells were detected by real-time PCR, Western blotting and immunofluorescence, respectively. PAX6 was overexpressed in HepG2 and LM3 cells, the cell growth and migration ability were detected by CCK-8 method and cell scratch assay, and the levels of sMICA and sULBP2 in the supernatant were detected by ELISA. Matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9) and disintegrin and metalloproteinase 10 (ADAM10) in HepG2 and LM3 cells were detected by Western blotting. The killing ability of NK cells against these 2 HCC cells was detected by flow cytometry. Compared with the healthy volunteers, the expressions of PAX6 in the HCC patients were significantly decreased (P=0.002), while the expression of sMICA and sULBP2 were significantly increased (P=0.004 and P<0.001, respectively). Real-time PCR and Western blotting results showed that compared with LO2 cells, mRNA and protein expressions of PAX6 in HepG2 and LM3 cells were significantly decreased (all P<0.05). Immunofluorescence results also showed that the expressions of PAX6 in HepG2 and LM3 were lower than those of LO2 cells. Compared with the NC group, the ability of proliferation and migration of HepG2 and LM3 cells were decreased (both P<0.05). The protein expressions of MMP2, MMP9 and ADAM10 in HepG2 and LM3 cells in the PAX6-OE group were significantly decreased, and the levels of sMICA and sULBP2 in superneant of HepG2 and LM3 cells in the PAX6-OE group were significantly lower than those in the NC group (all P<0.05). Flow cytometry results showed that compared with the NC group, the proportion of NK cells killing HepG2 and LM3 cells in PAX6-OE group was significantly increased (both P<0.05). The expression of PAX6 is decreased in serum of HCC patients and hepatocellular carcinoma cell lines. Overexpression of PAX6 can inhibit the growth of hepatocellular carcinoma cells, enhance the killing efficiency of NK cells against hepatoma cells. The mechanism is related to the inhibition of the expression of metalloproteinase via PAX6 and the decrease of the secretion levels of sMICA and sULBP2.

Long noncoding RNA MALAT1 inhibition attenuates sepsis-induced acute lung injury through modulating the miR-129-5p/PAX6/ZEB2 axis.

This research aimed to investigate the role of the long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/microRNA-129-5p (miR-129-5p)/paired box gene 6 (PAX6) axis in sepsis-induced acute lung injury (ALI). MLE-12 cells and C57BL/6 mice were induced by LPS to establish lung injury in in vitro and in vivo models. Cell viability and apoptosis were measured by cell counting kit-8 assay and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining, respectively. Levels of inflammatory cytokines in cell supernatants and bronchoalveolar lavage fluid (BALF) were detected by ELISA. Lung injury was evaluated by lung wet weight-to-dry weight ratio and hematoxylin-eosin staining. MALAT1, PAX6, and zinc finger E-box-binding homeobox 2 (ZEB2) expression was elevated and miR-129-5p expression was reduced in the serum of patients with sepsis-induced ALI, LPS-induced MLE-12 cells, and lung tissues of ALI mice. MALAT1 interference delayed the LPS-induced cell proliferation decrease, apoptosis increase, and inflammatory factor increase. miR-129-5p inhibition could reverse the delaying effect of MALAT1 interference on LPS-induced lung cell injury. PAX6 overexpression (oe) reversed the inhibitory effect of miR-129-5p oe on LPS-induced lung cell injury. Downregulating MALAT1 reduced pulmonary edema, inflammatory cytokine levels, lung injury, and apoptosis in ALI mice. Moreover, miR-129-5p suppression or PAX6 oe reversed the delaying effect of MALAT1 interference on sepsis-induced ALI. MALAT1 aggravates sepsis-induced ALI via the miR-129-5p/PAX6/ZEB2 axis.

Activation of cryptic donor splice sites by non-coding and coding PAX6 variants contributes to congenital aniridia

BackgroundThe paired-domain transcription factor paired box gene 6 (PAX6) causes a wide spectrum of ocular developmental anomalies, including congenital aniridia, Peters anomaly and microphthalmia. Here, we aimed to functionally assess...

Application of CRISPR/Cas9 genome editing technology in the research of eye diseases

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) is an adaptive immune system against invasive viruses and exogenous DNA, which is developed by bacteria and archaer during long-term evolution.With advances in technology, researchers have found that CRISPR/Cas9 system can precisely edit the genomes of eukaryotic cells through insertion, replacement or deletion of target genes.Using CRISPR/Cas9 genome editing technology, researchers found that overexpression of paired box gene 6 (PAX6) in cornea can cause congenital corneal epithelial damage; this technology promoted the research on the pathogenic mechanism of keratin 12 (KRT12) mutation in Meesmann corneal epithelial dystrophy; it has also built congenital cataract animal models by knocking out the GJA8 gene and αA lens gene, which is beneficial to the application of the diagnosis and pathological analysis of congenital cataract.In addition, the researchers have used CRISPR/Cas9 genome editing technology to confirm the correlation of RHOS334 mutated RHO allele, P23H mutated RHO gene, Y347X mutated Pde6b gene, and mutant RP9 allele with retinitis pigmentosa.The application of this technology has provided evidence to support the association of KCNJ13 gene and mutant CEP290 gene with Leber congenital amaurosis.CRISPR/Cas9 can provide target spot of intraocular neovascular diseases the targeted therapy by editing of VEGFR2 gene and TXNIP gene, and it also playse an important role in the study of pathogenic genes and establishment of animal models for proliferative vitreoretinopathy and retinoblastoma.In this review, we introduced the evolutionary history, the molecular characteristics and the mechanism of CRISPR/Cas9, and summarized its current research advances in eye diseases. Key words: CRISPR/Cas9; Gene editing technology; Eye diseases; Animal disease models; Gene therapy

A novel PAX6 nonsense mutation identified in an Iranian family with various eye anomalies

PurposeThe aim of this study was to detect the genetic defects in a large pedigree of affected individuals with various phenotypes of ocular anomalies including partial aniridia, congenital cataract, and nystagmus. MethodsThe entire coding region of paired box gene 6 (PAX6) was amplified by polymerase chain reaction (PCR), sequenced, and compared with a GenBank database. ResultsA novel mutation (c.1170 C > T; p.Gln297X) was found in the proband and all affected members. This nonsense mutation leads to PAX6 protein truncation. ConclusionsOur findings suggest that this novel mutation is most likely responsible for the pathogenesis of the congenital aniridia, cataract, and nystagmus in this pedigree. To the best of our knowledge, this is the first report of this mutation of PAX6 gene in a kindred pedigree with various ocular abnormalities.

Association of the PAX6 gene with extreme myopia rather than lower grade myopias

AimsTo investigate the association of the paired box gene 6 (PAX6) with different severities of myopia.MethodsA total of four haplotype-tagging single-nucleotide polymorphisms (SNPs; rs2071754, rs3026354, rs3026390 and rs628224) and two...

Experimental assessment of novel PAX6 splicing mutations in two Chinese families with aniridia

Aniridia is a rare, congenital ocular disorder caused by the mutations of the paired box gene-6 (PAX6) (OMIM 607108), which encodes a highly conserved transcriptional regulator. In order to investigate the clinical characterizations and genetic defects of two Chinese families affected with aniridia, we recruited the family members and 200 ethnically matched controls. The entire exons and flanking intronic sequences of the PAX6 gene (NG_008679.1) were analyzed and effects of variants on splicing were assessed in silico and in vitro using exon trapping assay with pET01. The donor site (c.1183+1G>A) mutation identified in family 1 would result in a complete skipping of exon 12 and cause a frameshift and run-on translation past the normal termination codon, creating an enlarged PAX6 protein with extended COOH-terminal domain. Novel c.1033-1_1033delinsCT mutation was detected in family 2. This mutation provoked both complete exon 12 skipping and partial skipping of exon 12 deleting 7bp. This would lead to a frameshift translation and the introduction of pre-mature termination code, which resulted in severely truncated PAX6 protein likely to be degraded. Our study further expands the spectrum of genetic pathology underlying PAX6.

Optimization of ultrastructure observation of human embryonic stem cell-derived retinal pigment epithelial cells

Background Normal ultrastructure is the anatomical basis of retinal pigment epithelial(RPE)cells to perform normal physiological function.At present the precipitation method is often used to detect the ultrastructure of RPE cells with transmission electron microscopy(TEM). Objective The aim of this study was to explore a simple and feasible approach to examine the ultrastructure of human embryonic stem cell-derived retinal pigment epithelial (hESC-RPE) cells. Methods hESCs were induced and differentiated into RPE cells by the spontaneous differentiation method, and the expressions of microphthalmia associated transcription factor MITF and paired-box gene 6 (PAX6), specific protein of RPE cells, in the cells were detected by immunofluorescence assay.hESC-RPE cells were inoculated into Transwell filter, and the ultrastructure of the cell sheet was examined under the TEM.Then the ultrastructure of the cell sheet specimens was compared with those of hESC-RPE cells from cell precipitation and RPE cell specimens of 90-day-old Long Evans rats. Results MITF and PAX6 were positively expressed in hESC-RPE cells.The normal ultrastructure were visible in the RPE cells of rats under the TEM, including apical microvilli, polarized melanin granules, cellular nucleus, basement membrane and intercellular junctions, and the ultrastructure of hESC-RPE cell sheet on Transwell was similar to the RPE cells in rats.However, only scatter melanin granules, nonpolar nucleus and scanty microvilli were observed under the TEM in the hESC-RPE cells by cell precipitation method. Conclusions Without digestion process, hESC-RPE cell sheet on Transwell can retain the normal ultrastructure of hESC-RPE cells under the TEM, with a more simple and reliable advantage. Key words: Retinal pigment epithelium/cytology; Embryonic stem cells; Microscopy, electron, transmission; Cell differentiation/physiology; Cells, cultured; Rats; Retinal pigment epithelial sheets, human

A nonsense PAX6 mutation in a family with congenital aniridia.

Congenital aniridia is a rare ocular malformation that presents with severe hypoplasia of the iris and various ocular manifestations. Most cases of congenital aniridia are known to be related to mutations in the paired box gene-6 (PAX6), which is an essential gene in eye development. Herein, we report a familial case of autosomal dominant congenital aniridia with four affected members in 3 consecutive generations and describe the detailed ophthalmologic findings for one of these members. As expected, mutational analysis revealed a nonsense mutation (p.Ser122*) in the PAX6 gene. Thus, our findings reiterate the importance of PAX6 mutations in congenital aniridia.

A novel PAX6 deletion in a Chinese family with congenital aniridia

Aniridia is a rare, congenital ocular disorder with the characteristics of incomplete formation of the iris caused by the mutations of the paired box gene-6 (PAX6). To investigate the clinical characterization and the underlying genetic defect in a Chinese family with autosomal dominant aniridia, we recruited the family members who underwent comprehensive ophthalmic examination. A novel heterozygous PAX6 deletion mutation c.796 del G (p.A266 fs) (GenBank ID: KP255960) in exon 10 was exclusively observed in all affected individuals but not in any of the unaffected family members or unrelated controls. The PAX6 mRNA level was about 50% lower in patients with aniridia than in unaffected family members, indicating that this mutation caused nonsense-mediated mRNA decay. In conclusion, we identified a novel deletion mutation in the PAX6 gene resulting in an abnormal PAX6 COOH-terminal extension in the Chinese family with aniridia. Our study further expands the mutation spectrum of PAX6.

A novel 11p13 microdeletion encompassing PAX6 in a Chinese Han family with aniridia, ptosis and mental retardation.

PurposeTo explore possible genetic aberrations in a Chinese family with aniridia, ptosis and mental retardation, and provide genetic evidence for the prenatal diagnosis.Methods14 exons of PAX6 in the proband were sequenced by the Sanger sequencing technique. Multiplex ligation-dependent probe amplification (MLPA) technique was employed to further explore gene alterations of PAX6. Single nucleotide polymorphisms-array (SNP-array) assay was applied to screen potential pathologic genome-wide copy number variations (CNV).ResultsThere were no detectable pathogenic mutations in the 14 exons of PAX6 in the proband. MLPA indicated a heterozygous deletion encompassing all PAX6 gene regions covered and a partial upstream region. SNP-array assay detected a heterozygous 11p13 microdeletion with a length of 518 kb in the proband, spanning two whole annotated genes, elongation factor protein 4 (ELP4), the paired box gene 6 (PAX6), and partial IMP1 inner-mitochondrial membrane (IMMP1L) gene. SNP-array revealed her affected brother carried the identical deletion.ConclusionsThe 518 kb heterozygous deletion in 11p13 encompassing PAX6 should be the genetic etiology for the familial aniridia.

A rare PAX6 mutation in a Chinese family with congenital aniridia.

Aniridia is an autosomal dominant disorder characterized by the complete or partial loss of the iris and is almost associated with mutations in the paired box gene 6 (PAX6). We examined three generations of a Chinese family with congenital aniridia and observed genetic defects. Exons of PAX6 from 12 family members were amplified by polymerase chain reaction, sequenced, and compared with reference sequences in NCBI reference sequence database (http://www.ncbi.nlm.nih.gov/nuccore/NG_008679.1?from=5001&to=38170&report=genbank). A rare mutation c.2T>A (M1K) in exon 4 of PAX6 was identified in all affected family members but not in unaffected family members. Our results suggest that the c.2T>A (M1K) mutation may be responsible for the pathogenesis of congenital aniridia in this family. To our knowledge, this is the first report of the M1K mutation in PAX6 in a Chinese family with this disease and the second report worldwide.

A novel duplication in the PAX6 gene in a North Indian family with aniridia.

Mutations in paired box gene 6 (PAX6) are the major cause of aniridia that may be associated with several other developmental anomalies of the eye, including microcornea in rare cases. Therefore, the purpose of this study was to identify the underlying genetic cause in a two-generation North Indian family diagnosed with aniridia. All the participants enrolled in the study, including the aniridia family and 20 healthy individuals (controls), underwent a comprehensive ophthalmic examination. Mutation screening was performed for the PAX6 gene by direct sequencing of the polymerase chain reaction products. A novel PAX6 duplication in exon 5 at position c.474dupC was identified in all three affected individuals from the family but not in the unaffected family members or unrelated controls. We reported a novel duplication in the PAX6 gene capable of causing the classic aniridia phenotype. This is the first report on the duplication in a North Indian family with autosomal dominant aniridia.

A novel de novo duplication mutation of PAX6 in a Chinese family with aniridia and other ocular abnormalities.

Aniridia is a congenital panocular disorder caused by the mutations of the paired box gene-6 (PAX6). To investigate the clinical characterization and the underlying genetic defect in a Chinese family with aniridia and other ocular abnormalities, we recruited the family members who underwent ophthalmic examination. Two patients in this family, the proband and his affected son, both have bilateral aniridia, foveal hypoplasia and nystagmus. Moreover, the proband also had presenile cataracts, but his affected son did not show cataracts at the time of examination. Sequencing PAX6 revealed that a heterozygous duplication mutation c.95_105dup11, predicted to generate non-functional truncated protein at position Gly36 (p.G36X), was found in the affected individuals but not in any of the unaffected family members including the parents of the proband. Haplotype analysis showed that the proband and his affected son shared a common disease-related haplotype, which was arisen from the proband's unaffected father through crossing-over. In conclusion, we identified a novel de novo duplication mutation of PAX6 in the aniridia and other ocular abnormalities family. This mutation has occurred de novo on a paternal chromosome by direct duplication, which presumably results from replication slippage or unequal non-sister chromatids exchange during spermatogenesis.

English

Aniridia are rare developmental anomalies present in 1.8/100, 000 live births. Aniridia occurs due to abnormal neuroectodermal development secondary to mutations in paired box gene 6 (PAX6) on band p13 of chromosome 11 which regulates eye development. Aniridia may be congenital or traumatic. It may occur in isolation or be associated with a number of syndromes such as WAGR. Two third of cases are familial and one third is sporadic. We report a family of aniridia with different clinical spectrum of features.

TGF-β receptor inhibitor Compound C promotes the directed differentiation of human embryonic stem cells into retinal pigment epithelial cells

Objective To observe the effect of TGF-β receptor inhibitor Compound C on the directed differentiation of human embryonic stem cells (hESC) into retinal pigment epithelial (RPE) cells.Methods H1 hESC were divided into control group and experimental group.When the hESC reached over confluence,the medium was changed to knockout serum replacement medium without bFGF to induce RPE differentiation.The experimental group was supplemented with 1 μmol/L TGF-β receptor inhibitor Compound C at the first six days of induction.Real-time PCR was carried out to examine the expression of paired-box gene 6 (PAX6),microphthalmia-associated transcription factor (MITF),cellular retinaldehyde blinding protein (CRALBP),and RPE65 in both groups at the 1,3,5 weeks of the induction process.hESC-derived RPE (hESC-RPE) cells were isolated mechanically and purified.Real-time PCR,Western blot and immunofluorescence were used to characterize the purified hESC-RPE cells.Results Pigmented colonies were observed in experimental group at the 4 weeks of the induction process,while no pigmented colony could be detected in the control group.All the purified pigmented cells from experimental group showed polygons morphology.Experimental group showed significantly higher expression of RPE marker genes PAX6,MITF,CRALBP and RPE65 than the control group(P＜0.05).Compared with the hESC and ARPE-19 cells line,purified hESC-RPE cells showed much higher expression of PAX6,MITF,CRALBP and RPE65(P＜0.05).High expression level of PAX6 and RPE65 proteins were observed in hESC-RPE cells.Immunofluorescence verified the expression of PAX6 and ZO-1 in hESC-RPE cells.Conclusion TGF β receptor inhibitor Compound C significantly improved the differentiation efficiency of hESC into RPE. Key words: TGF-beta superfamily proteins/antagonists & inhibitors; Embryonic stem cells/transplantation; Retinal pigment epithelium/cytology

Regulation of Human PAX6 Expression by miR-7.

The paired box gene 6 (PAX6) is a powerful mediator of eye and brain organogenesis whose spatiotemporal expression is exquisitely controlled by multiple mechanisms, including post-transcriptional regulation by microRNAs (miRNAs). In the present study, we use bioinformatic predictions to identify three candidate microRNA-7 (miR-7) target sites in the human PAX6 3′ untranslated region (3′-UTR) and demonstrate that two of them are functionally active in a human cell line. Furthermore, transient transfection of cells with synthetic miR-7 inhibits PAX6 protein expression but does not alter levels of PAX6 mRNA, suggesting that miR-7 induces translational repression of PAX6. Finally, a comparison of PAX6 3′-UTRs across species reveals that one of the functional miR-7 target sites is conserved, whereas the second functional target site is found only in primates. Thus, the interaction between PAX6 and miR-7 appears to be highly conserved; however, the precise number of sites through which this interaction occurs may have expanded throughout evolution.

A novel mutation of PAX6 identified in a Chinese twin family with congenital aniridia complicated with nystagmus

Genetic variations within the paired box gene 6 (PAX6) gene are associated with congenital aniridia. To detect the genetic defects in a Chinese twin family with congenital aniridia and nystagmus, exons of PAX6 were amplified by polymerase chain reaction (PCR), sequenced and compared with a reference database. Six members from the family of three generations were included in the study. The twins' father presented with congenital aniridia, nystagmus and cataract at birth, while the twins presented with congenital aniridia and nystagmus. A novel mutation c.888 insA in exon 10 of PAX6 was identified in all affected individuals. This study suggests that the novel mutation c.888 insA is likely responsible for the pathogenesis of the congenital aniridia and nystagmus in this pedigree. To the best of our knowledge, this is the first report of this mutation in PAX6 gene in pedigree with aniridia. Furthermore, no PAX6 gene defect was reported in twins with congenital aniridia.