Cloning and characterization of mouse mSox13 cDNA

Regulatory mechanisms of SoxD transcription factors and their influences on male fertility

Members of the SRY-related box (SOX) subfamily D (SoxD) of transcription factors are well conserved among vertebrate species and play important roles in different stages of male reproductive development. In mammals, the SoxD subfamily contains three members: SOX5, SOX6 and SOX13. Here, we describe their implications in testicular development and spermatogenesis, contributing to fertility. We also cover the mechanisms of action of SoxD transcription factors in gene regulation throughout male development. The specificity of activation of target genes by SoxD members depends, in part, on their post-translational modifications and interactions with other partners. Sperm production in adult males requires the coordination in the regulation of gene expression by different members of the SoxD subfamily of transcription factors in the testis. Specifically, the regulation of genes promoting adequate spermatogenesis by SoxD members is discussed in comparison between species.

Evaluation of PAX8 expression promotes the proliferation of stomach Cancer cells

Background

PAX8 was not only a mitotic factor, but identified as a transcription factor involved in the prognosis of human tumor patients. Elucidating the function of PAX8 on the pathology of stomach cancer was meaningful.

Results

PAX8 was found to be upregulated in primary stomach cancer tissue and the TCGA stomach cancer dataset. Interestingly, SOX13 and PAX8 showed consistent expression patterns, and the combined high PAX8 and SOX18 expression induced a worse prognosis of stomach cancer patients. SOX13 was further identified as a transcription factor of PAX8, and further affect Aurora B and Cyclin B1 expression, two cell cycle related factors of the downstream of PAX8, including. Furthermore, PAX8 depletion inducted G1-phase arrest and the decrease of EdU incorporation, cell viability and colony formation can be rescued by SOX13 overexpression.

Conclusions

SOX13 participated in the elevated expression of PAX8, which promote the proliferation of stomach cancer cells. Therefore, SOX13 mediated PAX8 expression was recognized as a tumor-promoting role in stomach cancer.

SOX13 dependent PAX8 expression promotes the proliferation of gastric carcinoma cells

PAX8 is identified as a regulator in the pathogenesis of human tumours and an indicator of the prognosis for patients. However, the role of PAX8 on proliferation in gastric cancer have not been studied. This study was aimed to explore the expression pattern of PAX8 in gastric cancer, and investigate the effect of PAX8 on the proliferation of gastric cancer cells. PAX8 and SOX13 were identified to be synchronously up-regulated in primary gastric cancer in human gastric cancer tissues and the gastric cancer datasets of TCGA, and gastric cancer patients of combined high PAX8 and SOX13 expression showed poor prognosis. Furthermore, SOX13 can mediate PAX8 and its targeted genes, Aurora B and Cyclin B1, expression in AGS and MGC803 cell lines. Flow cytometry and EdU incorporation assays showed that silencing PAX8 can block the cell cycle of gastric cancer cell in G1 phase and SOX13 expression can rescue the arrested proliferative process induced by PAX8 silenced in CCK8 and colony formation assays. Thus, combined SOX13 and PAX8 expression regulate the proliferation of gastric cancer cells, and both SOX13 and PAX8 play an oncogene function in gastric cancer.

Sox13 is a novel early marker for hair follicle development

Sox13, a group D member of the Sry-related high-mobility group box (Sox) transcription factor family, is expressed in various tissues including the hair follicle. However, its spatiotemporal expression patterns in the hair follicle and its role in hair development remain to be elucidated. To address these questions, we generated Sox13-LacZ-knock-in mice (Sox13^LacZ/+), in which the LacZ reporter gene was inserted in-frame into exon 2, which contains the translation initiation codon. X-gal staining in Sox13^LacZ/+ embryos revealed that Sox13 is initially expressed in the epithelial portion of the placode, and subsequently in the hair germ and the hair peg during early hair follicle development. In postnatal catagen and anagen, Sox13 was detected in the epithelial sheath, whereas in telogen, Sox13 was localized in the bulge region, where hair follicle stem cells reside. Immunohistochemistry with an anti-β-galactosidase antibody and anti-hair keratin antibodies that specifically mark the different layers of the hair follicle revealed that Sox13 was predominantly expressed in the outer root sheath in anagen. However, the integumentary structures of Sox13^LacZ/LacZ mice were grossly and histologically indistinguishable from those of wild type mice. These results suggest that although Sox13 is dispensable for epidermal and adnexal development, Sox13 is a useful marker for early hair follicle development.

Genome-wide identification and expression profiling of the SOX gene family in a bivalve mollusc Patinopecten yessoensis

SOX family is composed of transcription factors that play vital roles in various developmental processes. Comprehensive understanding on evolution of the SOX family requires full characterization of SOX genes in different phyla. Mollusca is the second largest metazoan phylum, but till now, systematic investigation on the SOX family is still lacking in this phylum. In this study, we conducted genome-wide identification of the SOX family in Yesso scallop Patinopecten yessoensis and profiled their tissue distribution and temporal expression patterns in the ovaries and testes during gametogenesis. Seven SOX genes were identified, including SOXB1, B2, C, D, E, F and H, representing the first record in protostomes with SOX members identical to that proposed to exist in the last common ancestor of chordates. Genomic structure analysis identified relatively conserved exon-intron structures, accompanied by intron insertion. Quantitative real-time PCR analysis revealed possible involvement of scallop SOX in various functions, including neuro-sensory cell differentiation, hematopoiesis, myogenesis and gametogenesis. This study represents the first systematic characterization of SOX gene family in Mollusca. It will assist in a better understanding of the evolution and function of SOX family in metazoans.

A systems-level approach reveals new gene regulatory modules in the developing ear

The inner ear is a complex vertebrate sense organ, yet it arises from a simple epithelium, the otic placode. Specification towards otic fate requires diverse signals and transcriptional inputs that act sequentially and/or in parallel. Using the chick embryo, we uncover novel genes in the gene regulatory network underlying otic commitment and reveal dynamic changes in gene expression. Functional analysis of selected transcription factors reveals the genetic hierarchy underlying the transition from progenitor to committed precursor, integrating known and novel molecular players. Our results not only characterize the otic transcriptome in unprecedented detail, but also identify new gene interactions responsible for inner ear development and for the segregation of the otic lineage from epibranchial progenitors. By recapitulating the embryonic programme, the genes and genetic sub-circuits discovered here might be useful for reprogramming naïve cells towards otic identity to restore hearing loss.

Summary: Transcriptome analysis and knock down of select transcription factors reveals a genetic hierarchy as cells become committed to inner ear fate.

Deficiency in IL-17-committed Vγ4(+) γδ T cells in a spontaneous Sox13-mutant CD45.1(+) congenic mouse substrain provides protection from dermatitis

Interleukin 17 (IL-17)-committed γδ T cells (γδT17 cells) participate in many immune responses, but their developmental requirements and subset specific functions remain poorly understood. Here we report that a commonly used CD45.1(+) congenic C57BL/6 mouse substrain is characterized by selective deficiency in Vγ4(+) γδT17 cells. This trait was due to a spontaneous mutation in the gene encoding the transcription factor Sox13 that caused an intrinsic defect in development of those cells in the neonatal thymus. The γδT17 cells migrated from skin to lymph nodes at low rates. In a model of psoriasis-like dermatitis, the Vγ4(+) γδT17 cell subset expanded considerably in lymph nodes and homed to inflamed skin. Sox13-mutant mice were protected from psoriasis-like skin changes, which identified a role for Sox13-dependent γδT17 cells in this inflammatory condition.

The SoxD transcription factors--Sox5, Sox6, and Sox13--are key cell fate modulators

Sox5, Sox6, and Sox13 constitute the group D of sex-determining region (Sry)-related transcription factors. They are highly conserved in the family-specific high-mobility-group (HMG) box DNA-binding domain and in a group-specific coiled-coil domain. The latter mediates SoxD protein dimerization and thereby preferential binding to pairs of DNA recognition sites. The SoxD genes have overlapping expression and cell-autonomously control discrete lineages. Sox5 and Sox6 redundantly enhance chondrogenesis, but retard gliogenesis. Sox5 hinders melanogenesis, promotes neural crest generation, and controls the pace of neurogenesis. Sox6 promotes erythropoiesis, and Sox13 modulates T cell specification and is an autoimmune antigen. SoxD proteins enhance transactivation by Sox9 in chondrocytes, but antagonize Sox9 and other SoxE proteins in oligodendrocytes and melanocytes, and also repress transcription through various mechanisms in several other lineages. While their biological and molecular functions remain incompletely understood, the SoxD proteins have thus already proven that they critically modulate cell fate in major lineages.

Control of cell fate and differentiation by Sry-related high-mobility-group box (Sox) transcription factors

Maintain stemness, commit to a specific lineage, differentiate, proliferate, or die. These are essential decisions that every cell is constantly challenged to make in multi-cellular organisms to ensure proper development, adult maintenance, and adaptability. SRY-related high-mobility-group box (Sox) transcription factors have emerged in the animal kingdom to help cells effect such decisions. They are encoded by 20 genes in humans and mice. They share a highly conserved high-mobility-group box domain that was originally identified in SRY, the sex-determining gene on the Y chromosome, and that has derived from a canonical high-mobility-group domain characteristic of chromatin-associated proteins. The high-mobility-group box domain binds DNA in the minor groove and increases its DNA binding affinity and specificity by interacting with many types of transcription factors. It also bends DNA and may thereby confer on Sox proteins a unique and critical role in the assembly of transcriptional enhanceosomes. Sox proteins fall into eight groups. Most feature a transactivation or transrepression domain and thereby also act as typical transcription factors. Each gene has distinct expression pattern and molecular properties, often redundant with those in the same group and overlapping with those in other groups. As a whole the Sox family controls cell fate and differentiation in a multitude of processes, such as male differentiation, stemness, neurogenesis, and skeletogenesis. We review their specific molecular properties and in vivo roles, stress recent advances in the field, and suggest directions for future investigations.

SOX13 exhibits a distinct spatial and temporal expression pattern during chondrogenesis, neurogenesis, and limb development

SOX13 is a member of the SOX family of transcription factors. SOX proteins play essential roles in development, and some are associated with human genetic diseases. SOX13 maps to a multi-disease locus on chromosome 1q31-32, yet its function is unknown. Here we describe the temporal and spatial expression of SOX13 protein during mouse organogenesis. SOX13 is expressed in the three embryonic cell lineages, suggesting that it may direct various developmental processes. SOX13 is expressed in the developing central nervous system including the neural tube and the developing brain. Expression is also detected in the condensing mesenchyme and cartilage progenitor cells during endochondral bone formation in the limb as well as the somite sclerotome and its derivatives. SOX13 is also detected in the developing kidney, pancreas, and liver as well as in the visceral mesoderm of the extra-embryonic yolk sac and spongiotrophoblast layer of the placenta.

A novel Xenopus laevis SRY-related gene, xSox33

The sex-determining region Y (SRY) gene and its related Sox genes encode transcriptional regulatory factors. In this study, we isolated and sequenced a novel Sox cDNA from African clawed frog (Xenopus laevis). The Sox gene was named xSox33. xSox33 was revealed to encode 244 amino acids. Reverse transcription-polymerase chain reaction (RT-PCR) showed that xSox33 was expressed at very low levels in some frog tissues including lung, ovary, skeletal muscle, testis, brain and heart. Its embryonic expression was also studied by RT-PCR. After the mid-blastula transition, the zygotic expression was initiated during gastrulation and the level was elevated as the embryogenesis proceeded. Electrophoretic mobility shift assay (EMSA) indicated that a recombinant xSox33 polypeptide was capable of binding to the nucleotide sequence AACAAT.

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.

Expression and characterization of Xenopus laevis SRY-related cDNAs, xSox17alpha1, xSox17alpha2, xSox18alpha and xSox18beta

Sox is a large family of genes related to the sex-determining region Y gene (designated as the SRY gene). Sox genes encoding DNA-binding transcriptional factors are found in many animals and are involved in developmental events. In this study, we newly isolated and sequenced novel Sox cDNAs from African clawed frog (Xenopus laevis). Five clones isolated here were classified into four distinct Sox genes designated as xSox17alpha1, xSox17alpha2, xSox18alpha and xSox18beta. All four belong to a subtype of SOX family, type F. The cDNA xSox17alpha1 contains essentially the same nucleotide sequence as that identified as Sox17alpha in a previous work (Cell 91 (1997) 397), whereas xSox17alpha2 is a distinct gene with high homology to xSox17alpha1. The clones, xSox18alpha and xSox18beta, are highly homologous to each other over the entire nucleotide sequences. The xSox18alpha and xSox18beta genes encode 363 and 361 amino acids, respectively. Genomic Southern hybridization analysis showed the existence of two copies of the xSox18. Northern analysis indicated that the xSox18 gene was expressed in the spleen and kidney and the size of the transcript was estimated to be 2.4 knt. Electrophoretic mobility shift assays indicated that recombinant xSox18 polypeptide was capable of binding to the HMG consensus nucleotide sequence, AACAAT.

Phylogeny of the SOX family of developmental transcription factors based on sequence and structural indicators

Members of the SOX family of transcription factors are found throughout the animal kingdom, are characterized by the presence of a DNA-binding HMG domain, and are involved in a diverse range of developmental processes. Previous attempts to group SOX genes and deduce their structural, functional, and evolutionary relationships have relied largely on complete or partial HMG box sequence of a limited number of genes. In this study, we have used complete HMG domain sequence, full-length protein structure, and gene organization data to study the pattern of evolution within the family. For the first time, a substantial number of invertebrate SOX sequences have been included in the analysis. We find support for subdivision of the family into groups A-H, as has been suggested in some previous studies, and for the assignment of two new groups, I and J. For vertebrate genes, it appears that relatedness as suggested by HMG domain sequence is congruent with relatedness as indicated by overall structure of the full-length protein and intron-exon structure of the genes. Most of the SOX groups identified in vertebrates were represented by a single SOX sequence in each invertebrate species studied. We have named anonymous sequences and, where appropriate, have suggested systematic names for some previously identified sequences. In addition, we identify an HMG domain signature motif which may be considered representative of the SOX family. Based on our data, we propose a robust phylogeny of SOX genes that reflects their evolutionary history in metazoans.

Genomic characterisation and fine mapping of the human SOX13 gene

SOX13 is the member of the SOX (Sry related HMG BOX) family of transcription factors which encodes the type-1 diabetes autoantigen, ICA12, and is expressed in a number of tissues including pancreatic islets and arterial walls. By fluorescence in situ hybridisation, radiation hybrid mapping and YAC analysis we determined that the human SOX13 gene maps to Chromosome 1q31.3-32.1 near the marker D1S504, a region associated with type-1 diabetes susceptibility and familial dilated cardiomyopathy. Mouse Sox13 maps to the syntenic region near the marker D1Mit57. The human SOX13 gene spans >15.5kb of genomic DNA and is composed of 14 exons with introns interrupting regions encoding the HMG DNA binding domain and the leucine zipper/glutamine-rich dimerisation domain. Comparison with the mouse Sox13 gene suggests the existence of long and short forms of the SOX13 protein which may arise by differential splicing during different stages in embryogenesis. The high sequence conservation between human SOX13 and mouse, Xenopus and trout orthologues implies a conserved function in vertebrates. SOX13 belongs to SOX Group D members which contain a leucine zipper/glutamine-rich region. Phylogenetic analyses of SOX proteins suggest that such domains were acquired after the initial divergence of groups A to G.

Isolation and characterization of a mouse SRY-related cDNA, mSox7

SOX is a family of SRY-related genes, which encode transcriptional factors involved in development. In this study, we newly isolated and sequenced mouse cDNA clones for mSox7. The mSox7 gene encodes 380 amino acids containing an SRY-type HMG box. Genomic Southern analysis suggested that the mSox7 gene was a single-copy gene. Tissue specific expression of mSox7 was investigated by Northern analysis. The expression was restricted to the ovary and heart, and the size of the transcripts was estimated to be 3.6 knt. Electrophoretic mobility shift assay indicated that recombinant mSox7 polypeptide was capable of binding to a nucleotide sequence, AACAAT. Immunohistochemical study revealed that mSox7 protein was localized in oocytes in the mouse ovary.

A new long form of Sox5 (L-Sox5), Sox6 and Sox9 are coexpressed in chondrogenesis and cooperatively activate the type II collagen gene

Transcripts for a new form of Sox5, called L-Sox5, and Sox6 are coexpressed with Sox9 in all chondrogenic sites of mouse embryos. A coiled-coil domain located in the N-terminal part of L-Sox5, and absent in Sox5, showed >90% identity with a similar domain in Sox6 and mediated homodimerization and heterodimerization with Sox6. Dimerization of L-Sox5/Sox6 greatly increased efficiency of binding of the two Sox proteins to DNA containing adjacent HMG sites. L-Sox5, Sox6 and Sox9 cooperatively activated expression of the chondrocyte differentiation marker Col2a1 in 10T1/2 and MC615 cells. A 48 bp chondrocyte-specific enhancer in this gene, which contains several HMG-like sites that are necessary for enhancer activity, bound the three Sox proteins and was cooperatively activated by the three Sox proteins in non-chondrogenic cells. Our data suggest that L-Sox5/Sox6 and Sox9, which belong to two different classes of Sox transcription factors, cooperate with each other in expression of Col2a1 and possibly other genes of the chondrocytic program.

The mouse Sox5 gene encodes a protein containing the leucine zipper and the Q box

The nucleotide sequence of mouse Sox5 (mSox5) cDNA derived from the testis has been reported by Denny et al. (EMBO J. 11 (1992) 3705-3712). We newly isolated an mSox5 cDNA derived from 8.5-day mouse embryo. Our cDNA encodes a protein of 763 amino acids, which is considerably larger in size than the previous one (392 amino acids) derived from the adult mouse testis. The most significant difference between the embryo-derived and testis-derived mSox5 cDNAs is that the embryonic one encodes a leucine zipper motif and a neighboring glutamine-rich sequence stretch (named Q box), but the testis-derived one does not. The leucine zipper and the Q box are highly conserved among type-D SOX proteins including mSox5. mSox5 was suggested to be a single-copy gene by Southern analysis. With reverse transcription/polymerase chain reaction, we found that not only mouse embryo, but also the adult mouse testis, express mSox5 mRNA species encoding the leucine zipper and the Q box.