A functional polymorphism in the 5' UTR of GDF5 is associated with susceptibility to osteoarthritis.

Osteoarthritis (MIM 165720), characterized by degeneration of articular cartilage, is the most common form of human arthritis and a major concern for aging societies worldwide. Epidemiological and genetic studies have shown that osteoarthritis is a polygenic disease. Here, we report that the gene encoding growth differentiation factor 5 (GDF5) is associated with osteoarthritis in Asian populations. A SNP in the 5' UTR of GDF5 (+104T/C; rs143383) showed significant association (P = 1.8 x 10(-13)) with hip osteoarthritis in two independent Japanese populations. This association was replicated for knee osteoarthritis in Japanese (P = 0.0021) and Han Chinese (P = 0.00028) populations. This SNP, located in the GDF5 core promoter, exerts allelic differences on transcriptional activity in chondrogenic cells, with the susceptibility allele showing reduced activity. Our findings implicate GDF5 as a susceptibility gene for osteoarthritis and suggest that decreased GDF5 expression is involved in the pathogenesis of osteoarthritis.

Non-monotonic relationships between arsenic and selenium excretion and its implication on arsenic methylation pattern in a Bangladeshi population.

The toxicity of arsenic differs markedly between individuals and populations, which might be related to the metabolism (methylation) of inorganic arsenic (As), as well as the selenium (Se) nutritional status. Urinary excretion of As (u-As) and Se (u-Se) was examined in an adult population (n=128) living in an As-contaminated area in Bangladesh. Although there was a significant negative correlation between u-Se and u-As (median 137; range 49-927 µg/g creatinine), closer examination revealed a non-monotonous relationship between them. A quadratic curve with an axis of As at 155 µg/g Cre gave a better fit, and u-As and u-Se were positively or negatively correlated depending on whether the As concentration was lower or higher than 155 µg As/g Cre, respectively. Likewise, the relationships between the As methylation pattern and glutathione-S-transferase (GST) polymorphism, body mass index (BMI), and u-Se differed depending on the u-As range; i.e., higher or lower than 155 µg/g Cre. Although we did not determine the causal mechanism for these observations, the non-monotonic relationship between As exposure and the variables examined suggested the existence of a threshold at which the handling of As by human body is qualitatively changed. The possible importance of Se nutrition for As toxicity is also discussed.

C/EBPß and RUNX2 cooperate to degrade cartilage with MMP-13 as the target and HIF-2α as the inducer in chondrocytes.

To elucidate the molecular mechanism underlying the endochondral ossification process during the skeletal growth and osteoarthritis (OA) development, we examined the signal network around CCAAT/enhancer-binding protein-ß (C/EBPß, encoded by CEBPB), a potent regulator of this process. Computational predictions and a C/EBP motif-reporter assay identified RUNX2 as the most potent transcriptional partner of C/EBPß in chondrocytes. C/EBPß and RUNX2 were induced and co-localized in highly differentiated chondrocytes during the skeletal growth and OA development of mice and humans. The compound knockout of Cebpb and Runx2 in mice caused growth retardation and resistance to OA with decreases in cartilage degradation and matrix metalloproteinase-13 (Mmp-13) expression. C/EBPß and RUNX2 cooperatively enhanced promoter activity of MMP13 through specific binding to a C/EBP-binding motif and an osteoblast-specific cis-acting element 2 motif as a protein complex. Human genetic studies failed to show the association of human CEBPB gene polymorphisms with knee OA, nor was there a genetic variation around the identified responsive region in the human MMP13 promoter. However, hypoxia-inducible factor-2α (HIF-2α), a functional and genetic regulator of knee OA through promoting endochondral ossification, was identified as a potent and functional inducer of C/EBPß expression in chondrocytes by the CEBPB promoter assay. Hence, C/EBPß and RUNX2, with MMP-13 as the target and HIF-2α as the inducer, control cartilage degradation. This molecular network in chondrocytes may represent a therapeutic target for OA.

An aspartic acid repeat polymorphism in asporin inhibits chondrogenesis and increases susceptibility to osteoarthritis.

Osteoarthritis is the most common form of human arthritis. We investigated the potential role of asporin, an extracellular matrix component expressed abundantly in the articular cartilage of individuals with osteoarthritis, in the pathogenesis of osteoarthritis. Here we report a significant association between a polymorphism in the aspartic acid (D) repeat of the gene encoding asporin (ASPN) and osteoarthritis. In two independent populations of individuals with knee osteoarthritis, the D14 allele of ASPN is over-represented relative to the common D13 allele, and its frequency increases with disease severity. The D14 allele is also over-represented in individuals with hip osteoarthritis. Asporin suppresses TGF-beta-mediated expression of the genes aggrecan (AGC1) and type II collagen (COL2A1) and reduced proteoglycan accumulation in an in vitro model of chondrogenesis. The effect on TGF-beta activity is allele-specific, with the D14 allele resulting in greater inhibition than other alleles. In vitro binding assays showed a direct interaction between asporin and TGF-beta. Taken together, these findings provide another functional link between extracellular matrix proteins, TGF-beta activity and disease, suggesting new therapeutic strategies for osteoarthritis.

An intronic SNP in a RUNX1 binding site of SLC22A4, encoding an organic cation transporter, is associated with rheumatoid arthritis.

Rheumatoid arthritis is a common inflammatory disease with complex genetic components. We investigated the genetic contribution of the cytokine gene cluster in chromosome 5q31 to susceptibility to rheumatoid arthritis in the Japanese population by case-control linkage disequilibrium (LD) mapping using single nucleotide polymorphisms (SNPs). Here we report that there is significant association between rheumatoid arthritis and the organic cation transporter gene SLC22A4 (P = 0.000034). We show that expression of SLC22A4 is specific to hematological and immunological tissues and that SLC22A4 is also highly expressed in the inflammatory joints of mice with collagen-induced arthritis. A SNP affects the transcriptional efficiency of SLC22A4 in vitro, owing to an allelic difference in affinity to Runt-related transcription factor 1 (RUNX1), a transcriptional regulator in the hematopoietic system. A SNP in RUNX1 is also strongly associated with rheumatoid arthritis (P = 0.00035). Our data indicate that the regulation of SLC22A4 expression by RUNX1 is associated with susceptibility to rheumatoid arthritis, which may represent an example of an epistatic effect of two genes on this disorder.

Development of a novel microarray data analysis tool without normalization for genotyping degraded forensic DNA.

Since the arrest of the Golden State Killer in the US in April 2018, forensic geneticists have been increasingly interested in the investigative genetic genealogy (IGG) method. While this method has already been in practical use as a powerful tool for criminal investigation, we have yet to know well the limitations and potential risks. In this current study, we performed an evaluation study focusing on degraded DNA using the Affymetrix Genome-Wide Human SNP Array 6.0 platform (Thermo Fisher Scientific). We revealed one of the potential problems that occur during SNP genotype determination using a microarray-based platform. Our analysis results indicated that the SNP profiles derived from degraded DNA contained many false heterozygous SNPs. In addition, it was confirmed that the total amount of probe signal intensity on microarray chips derived from degraded DNA decreased significantly. Because the conventional analysis algorithm performs normalization during genotype determination, we concluded that noise signals could be genotype-called. To address this issue, we proposed a novel microarray data analysis method without normalization (nMAP). Although the nMAP algorithm resulted in a low call rate, it substantially improved genotyping accuracy. Finally, we confirmed the usefulness of the nMAP algorithm for kinship inferences. These findings and the nMAP algorithm will make a contribution to the advance of the IGG method.

A common variant rs2054564 in ADAMST17 is associated with susceptibility to lumbar spondylosis.

The molecular pathophysiology underlying lumbar spondylosis development remains unclear. To identify genetic factors associated with lumbar spondylosis, we conducted a genome-wide association study using 83 severe lumbar spondylosis cases and 182 healthy controls and identified 65 candidate disease-associated single nucleotide polymorphisms (SNPs). Replication analysis in 510 case and 911 control subjects from five independent Japanese cohorts identified rs2054564, located in intron 7 of ADAMTS17, as a disease-associated SNP with a genome-wide significance threshold (P = 1.17 × 10-11, odds ratio = 1.92). This association was significant even after adjustment of age, sex, and body mass index (P = 7.52 × 10-11). A replication study in a Korean cohort, including 123 case and 319 control subjects, also verified the significant association of this SNP with severe lumbar spondylosis. Immunohistochemistry revealed that fibrillin-1 (FBN1) and ADAMTS17 were co-expressed in the annulus fibrosus of intervertebral discs (IVDs). ADAMTS17 overexpression in MG63 cells promoted extracellular microfibrils biogenesis, suggesting the potential role of ADAMTS17 in IVD function through interaction with fibrillin fibers. Finally, we provided evidence of FBN1 involvement in IVD function by showing that lumbar IVDs in patients with Marfan syndrome, caused by heterozygous FBN1 gene mutation, were significantly more degenerated. We identified a common SNP variant, located in ADAMTS17, associated with susceptibility to lumbar spondylosis and demonstrated the potential role of the ADAMTS17-fibrillin network in IVDs in lumbar spondylosis development.

Practical forensic use of kinship determination using high-density SNP profiling based on a microarray platform, focusing on low-quantity DNA.

Instead of traditional short tandem repeat (STR) profiling, the genetic genealogy method, which uses hundreds of thousands of single nucleotide polymorphisms (SNPs) spread across genome-wide, has emerged as a powerful kinship determination tool and recently attracted great attention in forensic genetics. In this study, we explored the tolerance and viability of kinship discrimination based on a high-density SNP profile for forensic DNA, especially focusing on low-quantity DNA. Using the Affymetrix Genome-Wide Human SNP Array 6.0 platform (Thermo Fisher Scientific), the influence of low-quantity DNA on SNP genotype determination was evaluated. The low-quantity DNA samples failed once every few samples, the generated SNP profile had low data quality. Our investigation revealed that the SNP profile with low data quality contained many genotyping errors in which the SNP genotype changed from homozygote to heterozygote. The kinship discrimination analysis using KING software was directly influenced by these genotyping errors, which was confirmed that some unrelated pairs were mis-specified as 4th-degree relatives. We confirmed that the false heterozygous SNPs resulted in an inflation of kinship coefficient and a decrease of non-shared allele between a tested pair. To eliminate the influence of these genotyping errors and acquire an accurate kinship discrimination result, we developed a novel method to select only the robust SNPs, which stably give the genotype determination with high accuracy even in SNP profiles with low data quality. The application of our novel method led to the improved results of kinship discrimination up to the same level as in the SNP profile with high data quality. In addition, this study demonstrated the advantage of kinship analysis using a high-density SNP profile in the forensic field. It is well known that likelihood ratio calculation based on autosomal STR profile, which is the most commonly applied approach, has difficulty in gaining true kinship analysis results, especially when the relationship between the tested two individuals is more biologically distant. We showed the kinship discrimination analysis with a high-density SNP profile is more suitable for the case without close relatives, using the real case data. Although further study with larger samples will be necessary, this study indicated that practical forensic use of kinship determination with a high-density SNP profile would bring benefits to the forensic field.

Meta-analysis of genome-wide association studies confirms a susceptibility locus for knee osteoarthritis on chromosome 7q22.

OBJECTIVES: Osteoarthritis (OA) is the most prevalent form of arthritis and accounts for substantial morbidity and disability, particularly in older people. It is characterised by changes in joint structure, including degeneration of the articular cartilage, and its aetiology is multifactorial with a strong postulated genetic component. METHODS: A meta-analysis was performed of four genome-wide association (GWA) studies of 2371 cases of knee OA and 35 909 controls in Caucasian populations. Replication of the top hits was attempted with data from 10 additional replication datasets. RESULTS: With a cumulative sample size of 6709 cases and 44 439 controls, one genome-wide significant locus was identified on chromosome 7q22 for knee OA (rs4730250, p=9.2 × 10⁻9), thereby confirming its role as a susceptibility locus for OA. CONCLUSION: The associated signal is located within a large (500 kb) linkage disequilibrium block that contains six genes: PRKAR2B (protein kinase, cAMP-dependent, regulatory, type II, ß), HPB1 (HMG-box transcription factor 1), COG5 (component of oligomeric golgi complex 5), GPR22 (G protein-coupled receptor 22), DUS4L (dihydrouridine synthase 4-like) and BCAP29 (B cell receptor-associated protein 29). Gene expression analyses of the (six) genes in primary cells derived from different joint tissues confirmed expression of all the genes in the joint environment.

Prevalence of knee osteoarthritis, lumbar spondylosis, and osteoporosis in Japanese men and women: the research on osteoarthritis/osteoporosis against disability study.

Musculoskeletal diseases, especially osteoarthritis (OA) and osteoporosis (OP), impair activities of daily life (ADL) and quality of life (QOL) in the elderly. Although preventive strategies for these diseases are urgently required in an aging society, epidemiological data on these diseases are scant. To clarify the prevalence of knee osteoarthritis (KOA), lumbar spondylosis (LS), and osteoporosis (OP) in Japan, and estimate the number of people with these diseases, we started a large-scale population-based cohort study entitled research on osteoarthritis/osteoporosis against disability (ROAD) in 2005. This study involved the collection of clinical information from three cohorts composed of participants located in urban, mountainous, and coastal areas. KOA and LS were radiographically defined as a grade of > or =2 by the Kellgren-Lawrence scale; OP was defined by the criteria of the Japanese Society for Bone and Mineral Research. The 3,040 participants in total were divided into six groups based on their age: < or =39, 40-49, 50-59, 60-69, 70-79, and > or =80 years. The prevalence of KOA in the age groups < or =39, 40-49, 50-59, 60-69, 70-79, and > or =80 years 0, 9.1, 24.3, 35.2, 48.2, and 51.6%, respectively, in men, and the prevalence in women of the same age groups was 3.2, 11.4, 30.3, 57.1, 71.9, and 80.7%, respectively. With respect to the age groups, the prevalence of LS was 14.3, 45.5, 72.9, 74.6, 85.3, and 90.1% in men, and 9.7, 28.6, 41.7, 55.4, 75.1, and 78.2% in women, respectively. Data of the prevalence of OP at the lumbar spine and femoral neck were also obtained. The estimated number of patients with KOA, LS, and L2-L4 and femoral neck OP in Japan was approximately 25, 38, 6.4, and 11 million, respectively. In summary, we estimated the prevalence of OA and OP, and the number of people affected with these diseases in Japan. The ROAD study will elucidate epidemiological evidence concerning determinants of bone and joint disease.

Identification of a two-SNP PLA2R1 Haplotype and HLA-DRB1 Alleles as Primary Risk Associations in Idiopathic Membranous Nephropathy.

The associations of single nucleotide polymorphisms (SNPs) in PLA2R1 and HLA-DQA1, as well as HLA-DRB1*15:01-DQB1*06:02 haplotype with idiopathic membranous nephropathy (IMN) is well known. However, the primary associations of these loci still need to be determined. We used Japanese-specific SNP genotyping array and imputation using 2,048 sequenced Japanese samples to fine-map PLA2R1 region in 98 patients and 413 controls. The most significant SNPs were replicated in a separate sample set of 130 patients and 288 controls. A two-SNP haplotype of intronic and missense SNPs showed the strongest association. The intronic SNP is strongly associated with PLA2R1 expression in the Genotype-Tissue Expression (GTEx) database, and the missense SNP is predicted to alter peptide binding with HLA-DRB1*15:01 by the Immune Epitope Database (IEDB). In HLA region, we performed relative predispositional effect (RPE) tests and identified additional risk alleles in both HLA-DRB1 and HLA-DQB1. We collapsed the risk alleles in each of HLA-DRB1 and HLA-DQB1 into single risk alleles. Reciprocal conditioning of these collapsed risk alleles showed more residual significance for HLA-DRB1 collapsed risk than HLA-DQB1 collapsed risk. These results indicate that changes in the expression levels of structurally different PLA2R protein confer risk for IMN in the presence of risk HLA-DRB1 alleles.

Identification of ITPA on chromosome 20 as a susceptibility gene for young-onset tuberculosis.

Tuberculosis (TB) is a complex disease, and both genetic and environmental factors contribute to disease progression. A previous genome-wide linkage study in Thailand determined that chromosome 20p13-12.3 may contain risk factors for young-onset disease. The present study aimed to identify novel susceptibility genes for young-onset TB within a 1-Mbp target region adjacent to the top-ranking risk marker in Chr.20p13-12.3. We performed next-generation sequencing (NGS) of the region in 13 young patients from multi-case families in Thailand. We then selected the functionally interesting single-nucleotide polymorphisms as candidates for subsequent analyses. The detected candidates rs13830 and rs1127354 in ITPA showed an association with young (<45 years old) TB patients. However, there was no association in old (⩾45 years old) patients. These findings confirm that stratifying patients based on age of TB onset can be important for identifying genetic risk factors for TB susceptibility. In addition, in silico expression quantitative trait loci analyses indicated that ITPA expression was associated with rs13830 genotype. This is the first study to use NGS resequencing to gain insight into host genetic factors associated with TB and to report a significant association for ITPA with host susceptibility in young-onset TB. The study also demonstrated the effectiveness of NGS in identifying susceptibility genes in common diseases.

High-density Association Mapping and Interaction Analysis of PLA2R1 and HLA Regions with Idiopathic Membranous Nephropathy in Japanese.

Although recent studies showed anti-PLA2R antibody plays a crucial role in idiopathic membranous nephropathy (IMN), detailed HLA mapping and interaction between the HLA genes and PLA2R1 have not been investigated in IMN. We genotyped across the PLA2R1 gene and the HLA region, using 183 IMN patients and 811 healthy controls. Five SNPs around the PLA2R1 gene were significantly associated with IMN. In addition to the two SNPs previously reported to be strongly associated with IMN, rs3749119 and rs35771982 (OR 3.02 and 2.93, P = 3.24E-14 and 4.64E-14, respectively), two novel intronic SNPs (rs2715928 and rs16844715) were also identified as IMN-associated SNPs (OR = 2.30 and 2.51, P = 3.15E-10 and 5.66E-13, respectively). In the HLA gene analysis, DRB1*1501 and DQB1*0602 were strongly associated with IMN (P = 1.14E-11 and 1.25E-11, respectively). The interaction was strongest between HLA-DRB1*15:01 - HLA-DQB1*06:02 and the intronic SNP rs2715928 (OR = 17.53, P = 4.26E-26). Furthermore, positive interaction was also observed between HLA-DRB1*15:01 - HLA-DQB1*06:02 and the missense SNP rs35771982 (OR = 15.91, P = 2.76E-29), which is in strong linkage disequilibrium with 5'UTR SNP rs3749119, and intronic SNP rs16844715 (OR = 15.91, P = 2.30E-26) for IMN. Neither HLA-DRB1*15:01 nor HLA-DQB1*06:02 was associated with steroid responsiveness, overall survival and renal survival during the observation period of mean 11 years though limited number of analysis.

Erratum: Novel rare variations of the oxytocin receptor (OXTR) gene in autism spectrum disorder individuals.

[This corrects the article DOI: 10.1038/hgv.2015.24.][This corrects the article DOI: 10.1038/hgv.2015.24.].

Novel rare variations of the oxytocin receptor (OXTR) gene in autism spectrum disorder individuals.

The oxytocin receptor (OXTR) gene has been implicated as a risk gene for autism spectrum disorder (ASD)-a neurodevelopmental disorder with essential features of impairments in social communication and reciprocal interaction. The genetic associations between common variations in OXTR and ASD have been reported in multiple ethnic populations. However, little is known about the distribution of rare variations within OXTR in ASD patients. In this study, we resequenced the full length of OXTR in 105 ASD individuals using an approach that combined the power of next-generation sequencing technology, long-range PCR and DNA pooling. We demonstrated that rare variants with minor allele frequency as low as 0.05% could be reliably detected by our method. We identified 28 novel variants including potential functional variants in the intron region and one rare missense variant (R150S). We subsequently performed Sanger sequencing and validated five novel variants located in previously suggested candidate regions in ASD individuals. Further sequencing of 312 healthy subjects showed that the burden of rare variants is significantly higher in ASDs compared with healthy individuals. Our results support that the rare variation in OXTR gene might be involved in ASD.

Association analysis of single nucleotide polymorphisms in cartilage-specific collagen genes with knee and hip osteoarthritis in the Japanese population.

Osteoarthritis (OA) is one of the most common diseases in the elderly. Although its pathophysiology is complex and its molecular basis remains to be determined, much evidence suggests that OA has strong genetic determinants. To search for susceptibility loci of OA, we selected seven candidate genes encoding cartilage-specific collagens (type II, IX, X, and XI collagens) and performed association analysis for OA using single nucleotide polymorphisms (SNPs) in the coding region of these genes. Four hundred seventeen OA samples and 280 control samples were collected from the Japanese population, and 12 SNPs were genotyped. Our studies have identified two susceptibility loci of OA: COL2A1 and COL9A3. An SNP in COL9A3 showed significant association with knee OA (p = 0.002, odds ratio [OR] = 1.48). Haplotype analysis showed significant association between a specific haplotype of COL2A1 and hip OA (p = 0.024; OR = 1.30). Further analysis of these two genes will shed light on the molecular mechanisms of OA.

Nucleotide pyrophosphatase gene polymorphism associated with ossification of the posterior longitudinal ligament of the spine.

Ossification of the posterior longitudinal ligament (OPLL) of the spine is a disease that causes paralysis by compressing the spinal cord. Based on the fact that the nucleotide pyrophosphatase (Npps) gene is responsible for ectopic ossification in ttw, an OPLL model mouse, the possibility was explored whether the human NPPS gene is associated with susceptibility to and severity of OPLL. First, we screened for single-nucleotide polymorphisms (SNPs) in the human NPPS locus using selected 25 OPLL patients with young onset (< 35 years old) or severe ossification (> 10 ossified vertebrae), and identified three novel SNPs in the locus. A case-control association study between 180 OPLL patients and 265 non-OPLL controls showed that one of these SNPs, IVS15-14T --> C substitution, was more frequently observed in OPLL patients (p = 0.022), especially in those with severe ossification (p < 0.0001) and young onset (p = 0.002), than in controls. A stratified study with the number of ossified vertebrae in OPLL patients revealed that IVS15-14T --> C substitution (p = 0.013) as well as young onset (p = 0.046) and female sex (p = 0.006) were associated with severe ossification. We conclude that the IVS15-14T --> C substitution in the human NPPS gene is associated not only with susceptibility to, but also with severity of OPLL.

Novel and recurrent mutations clustered in the von Willebrand factor A domain of MATN3 in multiple epiphyseal dysplasia.

Multiple epiphyseal dysplasia (MED) is a common skeletal dysplasia characterized by joint pain and stiffness, delayed and irregular ossification of epiphyses, and early-onset osteoarthritis. Six genes responsible for MED have been identified, including COMP, COL9A1, COL9A2, COL9A3, DSTDT and MATN3. MATN3 encodes matrilin-3, a cartilage-specific extracellular matrix protein. To date, seven different MATN3 mutations have been identified; all are located within the beta-sheet regions of the von Willebrand factor type A (vWFA) domain, which is encoded by exon 2. We examined MATN3 mutations in27 Japanese MED patients who were possibly autosomal dominant inheritance and had been excluded for COMP mutations. Ten of them had a positive family history. We examined all eight exons of MATN3 by PCR and direct sequencing from genomic DNA. We have identified four missense mutations in eight unrelated families; two are novel, and two have been characterized previously. Like previously characterized MATN3 mutations, those identified in this study are clustered within exon 2, specifically in and around the 2nd beta-sheet region of the vWFA domain (aa. 120-127). Contrary to the previous assumption that the MATN3 mutation in MED is confined to the beta-sheet regions, one novel mutation (p.F105S) is located outside the beta-sheet region, within an alpha-helix region.

Identification and characterization of the human long form of Sox5 (L-SOX5) gene.

The Sox (Sry-type HMG box) group of transcription factors, which is defined by a high-mobility group (HMG) DNA-binding domain, is categorized into six subfamilies. Sox5 and Sox6 belong to the group D subfamily, which is characterized by conserved N-terminal domains including a leucine-zipper, a coiled-coil domain and a Q-box. Group D Sox genes are expressed as long and short transcripts that exhibit differential expression patterns. In mouse, the long form of Sox5, L-Sox5, is co-expressed and interacts with Sox6; together, these two proteins appear to play a key role in chondrogenesis and myogenesis. In humans, however, only the short form of Sox5 has previously been identified. To gain insight into Sox5 function, we have identified and characterized human L-SOX5. The human L-SOX5 cDNA encodes a 763-amino-acid protein that is 416 residues longer than the short form and contains all of the characteristic motifs of group D Sox proteins. The predicted L-SOX5 protein shares 97% amino acid identity with its mouse counterpart and 59% identity with human SOX6. The L-SOX5 gene contains 18 exons and shows similar genomic structure to SOX6. We have identified two transcription start sites in L-SOX5 and multiple alternatively spliced mRNA variants that are distinct from the short form. Unlike the short form, which shows testis-specific expression, L-SOX5 is expressed in multiple tissues. Like SOX6, L-SOX5 shows strong expression in chondrocytes and striated muscles, indicating a likely role in human cartilage and muscle development.

Isolation, characterization and mapping of the mouse and human RB1CC1 genes.

RB1CC1 (RB1-inducible Coiled-Coil 1), a putative transcription factor implicated in the regulation of RB1 (retinoblastoma 1) expression, was recently identified in a screen for genes involved in multi-drug resistance to anticancer agents. Information about the RB1CC1 gene is limited, however, and its biological function is not determined. Here we report the isolation, characterization and mapping of the mouse RB1CC1 gene (Rb1cc1), together with further characterization of the human RB1CC1 gene. Mouse Rb1cc1 encodes 1588 amino acids, sharing 89% identity and key sequence motifs with its human counterpart. Rb1cc1 is expressed abundantly in heart and testis, with lower levels detected in lung and spleen. Immunohistochemical analysis revealed the Rb1cc1 and Rb1 proteins are co-localized in the cell nuclei of NIH3T3-3 cell and various mouse tissues. The human and mouse RB1CC1 genes, both of which contain 24 exons, span 74 kb on chromosome 8q11.2 and 57 kb on chromosome 1A2-4, respectively. Conserved sequence motifs and nuclear localization suggest that the RB1CC1 proteins function as transcription factors.