Genes & genetic systems最新文献

Duplicated genes show various degrees of functional diversification in plants. We previously identified 1,052 pairs of high diversified duplicates (HDDs) and 600 pairs of low diversified duplicates (LDDs) in Arabidopsis thaliana. Single knock-down of HDDs induced abnormal phenotypic changes because the other gene copy could not compensate for the knock-down effect, while single knock-down of LDDs did not induce abnormal phenotypic changes because of functional compensation by the copy gene. Here, focusing on one pair each of HDDs and LDDs, we performed transcriptome analyses in single-knock-down transgenic plants. The numbers of differentially expressed genes in single-knock-down transgenic plants were not different between HDDs and LDDs. Thus, functional compensation inferred by transcriptomics was similar between HDDs and LDDs. However, the trend of differentially expressed genes was similar in the pair of LDDs, while expression profiles were dissimilar in the pair of HDDs. This result indicates that a pair of LDDs tends to share similar functions but a pair of HDDs tends to have undergone functional divergence. Taking these findings together, as the reason for no phenotypic changes in single knock-down of LDDs but phenotypic changes in double knock-down of LDDs, we concluded that phenotypic changes of LDDs were induced by decreasing gene dosage.

Since the early phase of the coronavirus disease 2019 (COVID-19) pandemic, a number of research institutes have been sequencing and sharing high-quality severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes to trace the route of infection in Japan. To provide insight into the spread of COVID-19, we developed a web platform named SARS-CoV-2 HaploGraph to visualize the emergence timing and geographical transmission of SARS-CoV-2 haplotypes. Using data from the GISAID EpiCoV database as of June 4, 2022, we created a haplotype naming system by determining the ancestral haplotype for each epidemic wave and showed prefecture- or region-specific haplotypes in each of four waves in Japan. The SARS-CoV-2 HaploGraph allows for interactive tracking of virus evolution and of geographical prevalence of haplotypes, and aids in developing effective public health control strategies during the global pandemic. The code and the data used for this study are publicly available at: https://github.com/ktym/covid19/.

RNA-sequencing was used to develop 16 microsatellite markers for the pearly everlasting, Anaphalis margaritacea var. yedoensis (Franch. et Sav.) Ohwi (Asteraceae), which inhabits gravel bars throughout the Japanese archipelago. The mean number of alleles for these 16 markers in two populations in the Hokkaido and Shizuoka Prefectures, was 3.5 and 4.0, respectively, while the mean expected heterozygosity was 0.525 and 0.560, respectively, with a significant genetic differentiation between the two populations. All markers could also be amplified in two conspecific taxa, A. margaritacea var. margaritacea and var. angustifolia, whereas 11 of the 16 markers were amplifiable in two congeneric species, A. sinica and A. alpicola. These newly developed microsatellite markers will support understanding of population genetics and mating systems in A. margaritacea var. yedoensis, and several will potentially be of use in similar studies in other Anaphalis species.

Fagus pashanica is an endangered and endemic tree species in China. To understand its genetic diversity and structure for effective conservation, we used next-generation sequencing data to develop a set of microsatellite markers. Twenty-three of the 68 designed loci were successfully amplified. Fifteen polymorphic loci with clear peaks were selected for further analyses in three F. pashanica populations sampled from Nanjiang, Wangcang and Pingwu counties in Sichuan Province, China. The number of alleles per locus ranged from two to 11. The levels of observed and expected heterozygosity ranged from 0.033-0.852 and 0.033-0.787, respectively. All 23 loci were also successfully amplified in F. longipetiolata and F. lucida, and 19 were successfully amplified in F. engleriana. These microsatellite markers will be useful for population genetic studies of F. pashanica and other Fagus species.

Paired box 6 (PAX6) is a member of the PAX family and plays an essential role in cancer cell cycle progression, colony formation, proliferation and invasion. Its expression is upregulated in many cancers including breast cancer, but the process of PAX6 mRNA translation has rarely been studied. We found that PAX6 translation level increased in MCF-7 breast cancer cells treated with the chemotherapeutic drug adriamycin (ADM), which might be attributable to internal ribosome entry site (IRES)-mediated translation. By modifying a bicistronic luciferase plasmid that is widely used to examine IRES activity, we found that the 469-base 5'-UTR of PAX6 mRNA contains an IRES element and that core IRES activity is located between nucleotides 159 and 333. Moreover, PAX6 IRES activity was induced during ADM treatment, which may be the main reason for the elevated level of PAX6 protein. We also found that cymarin, a cardiac glycoside, acts as an inhibitor of PAX6 protein expression by impairing its IRES-mediated translation. Furthermore, MCF-7 cell proliferation was suppressed during treatment with cymarin. These results provide novel insights into the translation mechanism of PAX6 in breast cancer cells and suggest that cymarin is a promising candidate for the treatment of breast cancer via targeting the expression of PAX6.

Ectodermal dysplasia (ED), which exhibits a wide range of clinical symptoms, may be classified into three major types: hypohidrotic, anhidrotic, and hidrotic. A male child (proband) showing anhidrotic dysplasia was used as the subject of this study. The biopsy of the big toe revealed that the male child had no sweat glands. Genetic analysis of the patient revealed a mutation caused by a homozygous nucleotide substitution in the EDAR-associated death domain (EDARADD) (rs114632254) gene c.439G>A (p.Gly147Arg). Phenotypically, his teeth were sharp, but eight teeth were missing (oligodontia). The patient had normal nails with dry skin, sparse hair, everted lower lip vermilion, hyperpigmented eyelids, and abnormal nasal bridge morphology around the eyes. There is also a homozygous dominant (healthy) female and a heterozygous male in this family, who are cousins (aunt children) to the heterozygous parents. The daughter of the patient was also heterozygous. This mutation represents homozygous recessive inheritance, which we describe for the first time. Furthermore, we demonstrated that this genetic disorder can be readily diagnosed using the restriction fragment length polymorphism (RFLP) method after digestion with MnII restriction endonuclease.

Polyglutamine (polyQ) diseases are rare autosomal-dominant neurodegenerative diseases associated with the expansion of glutamine-encoding triplet repeats in certain genes. To investigate the functional influence of repeat expansion on disease mechanisms, we applied a biallelic genome-engineering platform that we recently established, called Universal Knock-in System or UKiS, to develop a human cell trio, a set of three isogenic cell lines that are homozygous for two different numbers of repeats (first and second lines) or heterozygous for the two repeat numbers (third line). As an example of a polyQ disease, we chose spinocerebellar ataxia type 2 (SCA2). In a pseudodiploid human cell line, both alleles of the glutamine-encoding triplet repeat in the SCA2-causing gene, ataxin 2 or ATXN2, were first knocked in with a donor sequence encoding both thymidine kinase and either puromycin or blasticidin resistance proteins under dual drug selection. The knocked-in donor alleles were then substituted with a payload having either 22 or 76 triplet repeats in ATXN2 by ganciclovir negative selection. The two-step substitution and subsequent SNP typing and genomic sequencing confirmed that the SCA2-modeling isogenic cell trio was obtained: three clones of 22-repeat homozygotes, two clones of 22/76-repeat heterozygotes and two clones of 76-repeat homozygotes. Finally, RT-PCR and immunoblotting using the obtained clones showed that, consistent with previous observations, glutamine tract expansion reduced transcriptional and translational expression of ATXN2. The cell clones with homozygous long-repeat alleles, which are rarely obtained from patients with SCA2, showed more drastic reduction of ATXN2 expression than the heterozygous clones. This study thus demonstrates the potential of UKiS, which is a beneficial platform for the efficient development of cell models not only for polyQ diseases but also for any other genetic diseases, which may accelerate our deeper understanding of disease mechanisms and cell-based screening for therapeutic drugs.

N6-methyladenosine (m6A) modifications are the most abundant internal modifications of mRNA and have a significant role in various cancers; however, the m6A methylome profile of oral squamous cell carcinoma (OSCC) in the mRNA-wide remains unknown. In this study, we examined the relationship between m6A and OSCC. Four pairs of OSCC and adjacent normal tissues were compared by Methylated RNA immunoprecipitation sequencing (MeRIP-seq). Gene Ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG), and Ingenuity Pathway Analysis (IPA) analyses were used to further analyze the MeRIP-seq data. A total of 2,348 different m6A peaks were identified in the OSCC group, including 85 m6A upregulated peaks and 2,263 m6A downregulated peaks. Differentially methylated m6A binding sites were enriched in the coding sequence in proximity to the stop codon of both groups. KEGG analysis revealed genes with upregulated m6A-modified sites in the OSCC group, which were prominently associated with the forkhead box O (FOXO) signaling pathway. Genes containing downregulated m6A-modified sites were significantly correlated with the PI3K/Akt signaling pathway, spliceosome, protein processing in the endoplasmic reticulum, and endocytosis. IPA analysis indicated that several genes with differential methylation peaks form networks with m6A regulators. Overall, this study established the mRNA-wide m6A map for human OSCC and indicated the potential links between OSCC and N6-methyladenosine modification.

Many organisms with heteromorphic sex chromosomes possess a mechanism of dosage compensation (DC) in which X-linked genes are upregulated in males to mitigate the dosage imbalance between sexes and between chromosomes. However, how quickly the DC is established during evolution remains unknown. In this study, by irradiating Drosophila miranda male flies, which carry young sex chromosomes (the so-called neo-sex chromosomes), with heavy-ion beams, we induced deletions in the neo-Y chromosome to mimic the condition of Y-chromosome degeneration, in which functional neo-Y-linked genes are nonfunctionalized; furthermore, we tested whether their neo-X-linked gametologs were immediately upregulated. Because the males that received 2-Gy iron-ion beam irradiation exhibited lower fertility, we sequenced the genomes and transcriptomes of six F₁ males derived from these males. Our pipeline identified 82 neo-Y-linked genes in which deletions were predicted in the F₁ males. Only three of them showed a one-to-one gametologous relationship with the neo-X-linked genes. The candidate deletions in these three genes occurred in UTRs and did not seriously affect their expression levels. These observations indirectly suggest that DC was unlikely to have operated on the neo-X-linked genes immediately after the pseudogenization of their neo-Y-linked gametologs in D. miranda. Therefore, the dosage imbalance caused by deletions in the neo-Y-linked genes without paralogs may not have effectively been compensated, and individuals with such deletions could have exhibited lethality. Future studies on sex chromosomes at different ages will further reveal the relationship between the age of sex chromosomes and the stringency of DC.

Eukaryotic cells contain multiple types of duplicated sequences. Typical examples are tandem repeat sequences including telomeres, centromeres, rDNA genes and transposable elements. Most of these sequences are unstable; thus, their copy numbers or sequences change rapidly in the course of evolution. In this review, I will describe roles of subtelomere regions, which are located adjacent to telomeres at chromosome ends, and recent discoveries about their sequence variation.