HMG Domain Research Articles

The molecular basis for functional divergence of duplicated SOX factors controlling endoderm formation and left-right patterning in zebrafish.

Endoderm, one of three primary germ layers of vertebrate embryos, makes major contributions to the respiratory and gastrointestinal tracts and associated organs, including liver and pancreas. In mammals, the transcription factor SOX17 is vital for endoderm organ formation and can induce endoderm progenitor identity. Duplication of ancestral sox17 in the teleost lineage produced the paralogues sox32 and sox17 in zebrafish. Sox32 is required for specification of endoderm and progenitors of the left-right organiser (Kupffer's Vesicle, KV), with Sox17 a downstream target of Sox32 that is implicated in further KV development. Phenotypic evidence therefore suggests functional similarities between zebrafish Sox32 and Sox17 and mammalian SOX17. Here, we directly compare these orthologues and paralogues, using the early zebrafish embryo as a biological platform for functional testing. Our results indicate that, unlike Sox32, human SOX17 cannot induce endoderm specification in zebrafish. Furthermore, using hybrid protein functional analyses, we show that Sox32 specificity for the endoderm gene regulatory network is linked to evolutionary divergence in its DNA-binding HMG domain from its paralogue Sox17. Additionally, changes in the C-terminal regions of Sox32 and Sox17 underpin their differing target specificities. Finally, we establish that specific conserved peptides in the C-terminal domain are essential for the role of Sox17 in establishing correct organ asymmetry. Overall, our results illuminate the molecular basis for functional divergence of Sox32 and Sox17 in vertebrate endoderm development and left-right patterning, and the evolution of SoxF transcription factor function.

CRISPR-Mediated SRY Gene Mutation Increases the Expression of Female Lineage-Specific Gene in Pre-Implantation Buffalo Embryo.

In mammals, sex determination is governed by the SRY gene on the Y chromosome, redirecting gonadal development from forming ovaries to testes. Mutations or alterations in the SRY gene can significantly affect phenotypic changes and lineage-specific markers. This study aims to elucidate the role of the SRY gene in buffalo embryos using CRISPR-Cas9 technology. We designed a crRNA targeting the HMG domain of the SRY gene using the CRISPOR algorithm. Nucleofection of sgRNA-Cas9 RNPs into buffalo fibroblasts confirmed efficient cleavage at the targeted site. Using this validated guide, we investigated the role of the SRY gene in sexual determination by electroporating CRISPR-Cas9-RNPs into single-stage zygotes of buffalo. Genetic changes in the SRY gene were confirmed through sequencing, revealing mosaic blastocysts with multiple alleles and non-mosaic mutants. Mutations in SRY gene increased the expression of female lineage-specific gene Wnt4 whereas decreased the expression of male specific gene SOX9 in blastocysts, suggesting reprogramming towards female sex determination pathways. Our findings provide insights into buffalo sex differentiation mechanisms and potential applications in reproductive strategies for breeding programmes.

9242 SOX11 mutations cause hypogonadotropic hypogonadism through both hypothalamic and pituitary level deficits

Abstract Disclosure: B. Sun: None. S. Stockman: None. M. Stamou: None. L. Plummer: None. K. Salnikov: None. D. Kotan: None. K. Topaloglu: None. S.B. Seminara: None. R. Balasubramanian: None. AbstractPurpose: Human SOX11 mutations cause Coffin-Siris Syndrome (CSS) which is clinically characterized by aplasia or hypoplasia of the distal phalanx/nail of the fifth digit, developmental delay, cognitive impairment, and distinctive facial features. Recent studies show hypogonadotropic hypogonadism (HH) occurs in ∼20% of patients with SOX11 mutations. The genotypic-phenotypic spectrum of SOX11 mutations in patients presenting with Idiopathic Hypogonadotropic Hypogonadism (IHH) is unknown. Methods: Exome sequencing data from 1810 unrelated IHH probands (anosmic and normosmic forms) were reviewed for SOX11 rare sequence variants (RSVs) [minor allele frequency <0.1%]. Rare variant association analysis (RVAS) and domain-based enrichment for SOX11 RSVs was performed between the IHH and gnomAD population cohort. RSVs predicted as pathogenic/likely pathogenic by ACMG criteria were deemed as pathogenic RSVs and detailed phenotypic analysis was undertaken for these variants. Results: A total of 4 pathogenic SOX11 RSVs were identified in 5 IHH cases. RVAS analysis showed that SOX11 inactivating RSVs (frameshift/non-sense) across the entire protein was enriched in the IHH cohort (2 RSVs in 3 IHH cases (p.S303X [de-novo]; p p.S345Afs*13); p<0.0001) while SOX11 missense RSVs was enriched only within the SOX11-HMG domain (2 RSVs in 2 IHH cases (p.G84D [de-novo]; p.P114S; p=0.003). Phenotypic review of individuals with pathogenic SOX11-RSVs revealed a spectrum of endocrine defects including: anosmic and normosmic forms of IHH, growth-hormone (GH) deficiency, neuroimaging defects (pituitary microadenoma and hypothalamic mass), and hypothyroidism. Additionally, we also identified a pathogenic SOX11 HMG domain RSV in a patient with functional HH (p.R100Q). CSS-associated features were present in almost all individuals with pathogenic SOX11 RSVs. Conclusions: This study validates SOX11 mutations as causal for IHH and reiterates the critical importance of the SOX11-HMG domain in disease pathogenesis. The spectrum of endocrine abnormalities in SOX11-related human disorders includes IHH, functional HH, GH deficiency, pituitary lesions, and hypothyroidism. The association of congenital anosmic and normosmic forms of IHH, functional HH, and anatomic abnormalities of the pituitary gland suggest that the pathogenesis of HH in SOX11-disorder may stem from both hypothalamic and pituitary level deficits. Presentation: 6/1/2024

8474 SOX11 mutations cause hypogonadotropic hypogonadism through both hypothalamic and pituitary level deficits

Abstract Disclosure: B. Sun: None. S. Stockman: None. M. Stamou: None. L. Plummer: None. K. Salnikov: None. D. Kotan: None. K. Topaloglu: None. S.B. Seminara: None. R. Balasubramanian: None. AbstractPurpose: Human SOX11 mutations cause Coffin-Siris Syndrome (CSS) which is clinically characterized by aplasia or hypoplasia of the distal phalanx/nail of the fifth digit, developmental delay, cognitive impairment, and distinctive facial features. Recent studies show hypogonadotropic hypogonadism (HH) occurs in ∼20% of patients with SOX11 mutations. The genotypic-phenotypic spectrum of SOX11 mutations in patients presenting with Idiopathic Hypogonadotropic Hypogonadism (IHH) is unknown. Methods: Exome sequencing data from 1810 unrelated IHH probands (anosmic and normosmic forms) were reviewed for SOX11 rare sequence variants (RSVs) [minor allele frequency <0.1%]. Rare variant association analysis (RVAS) and domain-based enrichment for SOX11 RSVs was performed between the IHH and gnomAD population cohort. RSVs predicted as pathogenic/likely pathogenic by ACMG criteria were deemed as pathogenic RSVs and detailed phenotypic analysis was undertaken for these variants. Results: A total of 4 pathogenic SOX11 RSVs were identified in 5 IHH cases. RVAS analysis showed that SOX11 inactivating RSVs (frameshift/non-sense) across the entire protein was enriched in the IHH cohort (2 RSVs in 3 IHH cases (p.S303X [de-novo]; p p.S345Afs*13); p<0.0001) while SOX11 missense RSVs was enriched only within the SOX11-HMG domain (2 RSVs in 2 IHH cases (p.G84D [de-novo]; p.P114S; p=0.003). Phenotypic review of individuals with pathogenic SOX11-RSVs revealed a spectrum of endocrine defects including: anosmic and normosmic forms of IHH, growth-hormone (GH) deficiency, neuroimaging defects (pituitary microadenoma and hypothalamic mass), and hypothyroidism. Additionally, we also identified a pathogenic SOX11 HMG domain RSV in a patient with functional HH (p.R100Q). CSS-associated features were present in almost all individuals with pathogenic SOX11 RSVs. Conclusions: This study validates SOX11 mutations as causal for IHH and reiterates the critical importance of the SOX11-HMG domain in disease pathogenesis. The spectrum of endocrine abnormalities in SOX11-related human disorders includes IHH, functional HH, GH deficiency, pituitary lesions, and hypothyroidism. The association of congenital anosmic and normosmic forms of IHH, functional HH, and anatomic abnormalities of the pituitary gland suggest that the pathogenesis of HH in SOX11-disorder may stem from both hypothalamic and pituitary level deficits. Presentation: 6/1/2024

The role of HMGB2 in the immune response of Nile tilapia (Oreochromis niloticus) to streptococcal infection

High mobility group protein B2 (HMGB2) is an abundant chromatin-associated protein with pivotal roles in transcription, cell proliferation, differentiation, inflammation, and tumorigenesis. However, its immune function in Nile tilapia (Oreochromis niloticus) remains unclear. In this study, we identified a homologue of HMGB2 from Nile tilapia (On-HMGB2) and investigated its functions in the immune response against streptococcus infection. The open reading frame (ORF) of On-HMGB2 spans 642 bp, encoding 213 amino acids, and contains two conserved HMG domains. On-HMGB2 shares over 80 % homology with other fish species and 74%–76 % homology with mammals. On-HMGB2 was widely distributed in various tissues, with its highest transcript levels in the liver and the lowest in the intestine. Knockdown of On-HMGB2 promoted the inflammatory response in Nile tilapia, increased the bacterial load in the tissues, and led to elevated mortality in Nile tilapia following Streptococcus agalactiae infection. Taken together, On-HMGB2 significantly influences the immune system of Nile tilapia in response to streptococcus infection.

Abstract Introduction of a novel pathogenic variant (c.1684G>A) in the SOX5 gene associated with Lamb– Shaffer syndrome in a family from north of Iran

So far, different types of SOX5 variants have been reported in patients with LAMSHF syndrome, which are mainly clustered in the HMG domain. The LAMSHF syndrome has a broad variety of clinical manifestations such as developmental delay, speech delay, intellectual disability, and behavioral disturbances. In this article, we aim to present three cases with Lamb–Shaffer syndrome who are heterozygotes for a novel variant (c.1684G>A) in the SOX5 gene in a family from the north of Iran. A 38-year-old male case with moderate mental retardation and strabismus, with a head circumference size of 56 cm, was tested for genetic diagnosis. The results of wholeexome sequencing (WES) indicated the c.1684G>A pathogenic variant (NM_006940.6) in the SOX5 gene in a heterozygote state. Family analysis showed that the proband’s sister and father, who have similar symptoms, also carry the detected variant. Like the previous cases, the presented cases with a missense variant in the HMGdomain also have a mild phenotype. The introduction of new patients, especially with new pathogenic variants, is fundamental to increasing our knowledge about the disease and possible genotype–phenotype correlations.

Identification of a novel phenotype of external ear deformity related to Coffin-Siris syndrome-9 and literature review.

De novo germline variants of the SRY-related HMG-box 11 gene (SOX11) have been reported to cause Coffin-Siris syndrome-9 (CSS-9), a rare congenital disorder associated with multiple organ malformations, including ear anomalies. Previous clinical and animal studies have found that intragenic pathogenic variant or haploinsufficiency in the SOX11 gene could cause inner ear malformation, but no studies to date have documented the external ear malformation caused by SOX11 deficiency. Here, we reported a Chinese male with unilateral microtia and bilateral sensorineural deafness who showed CSS-like manifestations, including dysmorphic facial features, impaired neurodevelopment, and fingers/toes malformations. Using trio-based whole-exome sequencing, a de novo missense variant in SOX11 (NM_003108.4: c.347A>G, p.Y116C) was identified and classified as pathogenic variant as per American College of Medical Genetics guidelines. Moreover, a systematic search of the literature yielded 12 publications that provided data of 55 SOX11 intragenic variants affecting various protein-coding regions of SOX11 protein. By quantitatively analyzing phenotypic spectrum information related to these 56 SOX11 variants (including our case), we found variants affecting different regions of SOX11 protein (high-mobility group [HMG] domain and non-HMG regions) appear to influence the phenotypic spectrum of organ malformations in CSS-9; variants altering the HMG domain were more likely to cause the widest range of organ anomalies. In summary, this is the first report of CSS with external ear malformation caused by pathogenic variant in SOX11, indicating that the SOX11 gene may be not only essential for the development of the inner ear but also critical for the morphogenesis of the external ear. In addition, thorough clinical examination is recommended for patients who carry pathogenic SOX11 variants that affect the HMG domain, as these variants may cause the widest range of organ anomalies underlying this condition.

Xenopus Sox11 Partner Proteins and Functional Domains in Neurogenesis.

Sox11, a member of the SoxC family of transcription factors, has distinct functions at different times in neural development. Studies in mouse, frog, chick, and zebrafish show that Sox11 promotes neural fate, neural differentiation, and neuron maturation in the central nervous system. These diverse roles are controlled in part by spatial and temporal-specific protein interactions. However, the partner proteins and Sox11-interaction domains underlying these diverse functions are not well defined. Here, we identify partner proteins and the domains of Xenopus laevis Sox11 required for protein interaction and function during neurogenesis. Our data show that Sox11 co-localizes and interacts with Pou3f2 and Neurog2 in the anterior neural plate and in early neurons, respectively. We also demonstrate that Sox11 does not interact with Neurog1, a high-affinity partner of Sox11 in the mouse cortex, suggesting that Sox11 has species-specific partner proteins. Additionally, we determined that the N-terminus including the HMG domain of Sox11 is necessary for interaction with Pou3f2 and Neurog2, and we established a novel role for the N-terminal 46 amino acids in the specification of placodal progenitors. This is the first identification of partner proteins for Sox11 and of domains required for partner-protein interactions and distinct roles in neurogenesis.

Genome-Wide Identification, Evolutionary and Mutational Analysis of the Buffalo Sox Gene Family.

The Sox gene family constitutes transcription factors with a conserved high mobility group box (HMG) that regulate a variety of developmental processes, including sex differentiation, neural, cartilage, and early embryonic development. In this study, we systematically analyzed and characterized the 20 Sox genes from the whole buffalo genome, using comparative genomic and evolutionary analyses. All the buffalo Sox genes were divided into nine sub-groups, and each gene had a specific number of exons and introns, which contributed to different gene structures. Molecular phylogeny revealed more sequence similarity of buffalo Sox genes with those of cattle. Furthermore, evolutionary analysis revealed that the HMG domain remained conserved in the all members of the Sox gene family. Similarly, all the genes are under strong purifying selection pressure; seven segmental duplications occurred from 9.65 to 21.41 million years ago (MYA), and four potential recombination breakpoints were also predicted. Mutational analysis revealed twenty non-synonymous mutations with potential effects on physiological functions, including embryonic development and cell differentiation in the buffalo. The present study provides insights into the genetic architecture of the Sox gene family in buffalo, highlights the significance of mutations, and provides their potential utility for marker-assisted selection for targeted genetic improvement in buffalo.

OTUD7B Activates Wnt Signaling Pathway through the Interaction with LEF1.

The Wnt signaling pathway plays a critical role in regulating normal cellular processes, including proliferation, differentiation, and apoptosis. Dysregulation of Wnt signaling has been implicated in various human diseases, including cancer. β-catenin and LEF1 are key mediators of Wnt signaling, and their dysregulation is a hallmark of many cancer types. In this study, we aimed to identify the deubiquitinases (DUBs) that regulate the Wnt signaling pathway through the essential component LEF1. Screening candidate DUBs from the human DUB library, we discovered that OTUD7B interacts with LEF1 and activates Wnt signaling. OTUD7B and LEF1 interact with each other through the UBA and HMG domains, respectively. Furthermore, OTUD7B promotes the nuclear localization of LEF1, leading to an increased interaction with β-catenin in the nucleus while not noticeably affecting ubiquitination on LEF1. Using qPCR array analysis, we found that OTUD7B overexpression leads to an upregulation of 75% of the tested Wnt target genes compared to the control. These findings suggest that OTUD7B may serve as a potential therapeutic target in human diseases, including cancers where Wnt signaling is frequently dysregulated.

MAEL facilitates metabolic reprogramming and breast cancer progression by promoting the degradation of citrate synthase and fumarate hydratase via chaperone-mediated autophagy.

Metabolic reprogramming is a hallmark of cancer. Several studies have shown that inactivation of Krebs cycle enzymes, such as citrate synthase (CS) and fumarate hydratase (FH), facilitates aerobic glycolysis and cancer progression. MAEL has been shown to play an oncogenic role in bladder, liver, colon, and gastric cancers, but its role in breast cancer and metabolism is still unknown. Here, we demonstrated that MAEL promoted malignant behaviours and aerobic glycolysis in breast cancer cells. Mechanistically, MAEL interacted with CS/FH and HSAP8 via its MAEL domain and HMG domain, respectively, and then enhanced the binding affinity of CS/FH with HSPA8, facilitating the transport of CS/FH to the lysosome for degradation. MAEL-induced degradation of CS and FH could be suppressed by the lysosome inhibitors leupeptin and NH4 Cl, but not by the macroautophagy inhibitor 3-MA or the proteasome inhibitor MG132. These results suggested that MAEL promoted the degradation of CS and FH via chaperone-mediated autophagy (CMA). Further studies showed that the expression of MAEL was significantly and negatively correlated with CS and FH in breast cancer. Moreover, overexpression of CS or/and FH could reverse the oncogenic effects of MAEL. Taken together, MAEL promotes a metabolic shift from oxidative phosphorylation to glycolysis by inducing CMA-dependent degradation of CS and FH, thereby promoting breast cancer progression. These findings have elucidated a novel molecular mechanism of MAEL in cancer.

Loss-of-function mutations of SOX17 lead to YAP/TEAD activation-dependent malignant transformation in endometrial cancer.

Aberrant hyperactivation of the Hippo pathway effector YAP/TEAD complex causes tissue overgrowth and tumorigenesis in various cancers, including endometrial cancer (EC). The transcription factor SOX17 (SRY [sex-determining region Y]-box 17) is frequently mutated in EC; however, SOX17 mutations are rare in other cancer types. The molecular mechanisms underlying SOX17 mutation-induced EC tumorigenesis remain poorly understood. Here, we demonstrate that SOX17 serves as a tumor suppressor to restrict the proliferation, migration, invasion, and anchorage-independent growth of EC cells, partly by suppressing the transcriptional outputs of the Hippo-YAP/TEAD pathway. SOX17 binds to TEAD transcription factors through its HMG domain and attenuates the DNA-binding ability of TEAD. SOX17 loss by inactivating mutations leads to the malignant transformation of EC cells, which can be reversed by small-molecule inhibitors of YAP/TEAD or cabozantinib, an FDA-approved drug targeting the YAP/TEAD transcriptional target AXL. Our findings reveal novel molecular mechanisms underlying Hippo-YAP/TEAD pathway-driven EC tumorigenesis, and suggest potential therapeutic strategies targeting the Hippo-YAP/TEAD pathway in SOX17-mutated EC.

Abstract 13304: Sox17 Deficiency Induces Pulmonary Hypertension Through E2F1/BRD4 Signaling

Introduction: Pulmonary arterial hypertension (PAH) is a disaster disease characterized by obliterative vascular remodeling and persistent increase of vascular resistance, leading to right heart failure and premature death. Understanding the cellular and molecular mechanisms will help develop novel therapeutic approaches for PAH patients. Hypothesis: Genetic SOX17 mutations are associated with PAH. We hypothesized that endothelial SOX17 mutations or loss of function contributes to endothelial dysfunction and the pathogenesis of PAH. Methods: Endothelial-specific deletion of Sox17 ( Sox17iCKO ) mice were generated. Sox17iCKO and Sox17f/f (WT) mice after tamoxifen injection were incubated without or with hypoxia (10% O 2 ) for 3 weeks to induce PH. EC proliferation, apoptosis, cell junction assay, Western blotting, QRT-PCR, RNA-sequencing analysis, and luciferase assays were performed to understand the molecular mechanisms of SOX17 deficiency and mutation in ECs. siRNA and inhibitors were used to determine the involvement of E2F1/BRD4 signaling in SOX17 deficiency ECs. Results: Sox17iCKO mice developed spontaneous mild PH and exaggerated hypoxia-induced PH evidenced by the increase of RVSP and RV hypertrophy compared to WT mice. SOX17 knockdown in human PVECs induced cell proliferation, anti-apoptosis, and impaired cell integrity. SOX17 knockdown reduced BMPR2 signaling. SOX17 knockdown and mutations at the HMG domain lost transcriptional activities and its ability to repress -catenin. RNA-seq analysis demonstrated enrichment of cell cycle pathway after the loss of SOX17 in PVECs. iRegulon analysis revealed the involvement of transcriptional factor E2F1. siRNA-mediated E2F1 knockdown normalized SOX17 deficiency-induced PVECs dysfunction. Knockdown SOX17 significantly upregulated E2F1 promoter activity, which was dependent on the binding site in the E2F1 promoter by luciferase and mutagenesis assay. E2F1 or BRD4 inhibitors attenuated SOX17 deficiency-induced PH in mice. Conclusions: Our study demonstrated that endothelial loss of SOX17 induces PH in mice. Pharmacological inhibition of E2F1/BRD4 signaling attenuated PH development in Sox17iCKO mice.

HMG20A Inhibit Adipogenesis by Transcriptional and Epigenetic Regulation of MEF2C Expression.

Obesity and its associated metabolic disease do serious harm to human health. The transcriptional cascade network with transcription factors as the core is the focus of current research on adipogenesis and its mechanism. Previous studies have found that HMG domain protein 20A (HMG20A) is highly expressed in the early stage of adipogenic differentiation of porcine intramuscular fat (IMF), which may be involved in regulating adipogenesis. In this study, HMG20A was found to play a key negative regulatory role in adipogenesis. Gain- and loss-of-function studies revealed that HMG20A inhibited the differentiation of SVF cells and C3H10T1/2 cells into mature adipocytes. RNA-seq was used to screen differentially expressed genes after HMG20A knockdown. qRT-PCR and ChIP-PCR confirmed that MEF2C was the real target of HMG20A, and HMG20A played a negative regulatory role through MEF2C. HMG20A binding protein LSD1 was found to alleviate the inhibitory effect of HMG20A on adipogenesis. Further studies showed that HMG20A could cooperate with LSD1 to increase the H3K4me2 of the MEF2C promoter and then increase the expression of MEF2C. Collectively, these findings highlight a role for HMG20A-dependent transcriptional and epigenetic regulation in adipogenesis.

Molecular cloning and functional characterization of HMGB1 and HMGB2 in large yellow croaker Larimichthys crocea

High mobility group box 1 (HMGB1) and HMGB2 have been demonstrated to be key regulators not only in DNA recombination, replication, gene transcription, but also in host inflammation and immune responses. In the present study, orthologs of HMGB1 and HMGB2 named Lc-HMGB1 and Lc-HMGB2 were characterized in large yellow croaker (Larimichthys crocea). The ORFs of Lc-HMGB1 and Lc-HMGB2 are 621 bp and 648 bp, encoding proteins of 206 aa and 215 aa, with the putative Lc-HMGB1 and Lc-HMGB2 proteins both contain two HMG domains, respectively. The genome organizations of Lc-HMGB1 and Lc-HMGB2 are both composed of four exons and three introns, which are conserved in vertebrates. Lc-HMGB1 and Lc-HMGB2 were identified as cell nucleus localized proteins, and were ubiquitously distributed in the examined organs/tissues. Additionally, Lc-HMGB1 was significantly up-regulated under LPS and PGN stimulation, whereas the stimulation of poly I:C, LPS, PGN, and Pseudomonas plecoglossicida infection could significantly induce Lc-HMGB2 expression in vivo. Notably, both Lc-HMGB1 and Lc-HMGB2 overexpression could significantly up-regulated the expression of diverse immune-related genes, including IFN1, IRF3, ISG15, ISG56, RSAD2, g-type lysozyme, and TNF-α. Moreover, overexpression of Lc-HMGB1 could also induce the expression of IRF7 and Mx. These results collectively indicate that Lc-HMGB1 and Lc-HMGB2 play important roles in host immune responses against pathogen infection.

A Method for In Situ Reverse Genetic Analysis of Proteins Involved mtDNA Replication.

The unavailability of tractable reverse genetic analysis approaches represents an obstacle to a better understanding of mitochondrial DNA replication. Here, we used CRISPR-Cas9 mediated gene editing to establish the conditional viability of knockouts in the key proteins involved in mtDNA replication. This observation prompted us to develop a set of tools for reverse genetic analysis in situ, which we called the GeneSwap approach. The technique was validated by identifying 730 amino acid (aa) substitutions in the mature human TFAM that are conditionally permissive for mtDNA replication. We established that HMG domains of TFAM are functionally independent, which opens opportunities for engineering chimeric TFAMs with customized properties for studies on mtDNA replication, mitochondrial transcription, and respiratory chain function. Finally, we present evidence that the HMG2 domain plays the leading role in TFAM species-specificity, thus indicating a potential pathway for TFAM-mtDNA evolutionary co-adaptations.

EP459: Rare clinical gene variant of SOX9: Acampomelic campomelic dysplasia

eP459: Rare clinical gene variant of SOX9: Acampomelic campomelic dysplasia

MAP4K4 mediates the SOX6-induced autophagy and reduces the chemosensitivity of cervical cancer

There are nearly 40% of cervical cancer patients showing poor response to neoadjuvant chemotherapy that can be induced by autophagy, however, the underlying mechanism has not yet been fully clarified. We previously found that Sex-determining region of Y-related high-mobility-group box 6 (SOX6), a tumor suppressor gene or oncogene in several cancers, could induce autophagy in cervical cancer. Accordingly, this study aims to investigate the mechanism of SOX6-induced autophagy and its potential significance in the platinum-based chemotherapy of cervical cancer. Firstly, we found that SOX6 could promote autophagy in cervical cancer cells depending on its HMG domain. Mitogen-activated protein kinase kinase kinase kinase-4 (MAP4K4) gene was identified as the direct target gene of SOX6, which was transcriptionally upregulated by binding the HMG domain of SOX6 protein to its double-binding sites within MAP4K4 gene promoter. MAP4K4 mediated the SOX6-induced autophagy through inhibiting PI3K-Akt-mTOR pathway and activating MAPK/ERK pathway. Further, the sensitivity of cervical cancer cells to cisplatin chemotherapy could be reduced by the SOX6-induced autophagy in vitro and in vivo, while such a phenomenon could be turned over by autophagy-specific inhibitor and MAP4K4 inhibitor, respectively. Moreover, cisplatin itself could promote the expression of endogenous SOX6 and subsequently the MAP4K4-mediated autophagy in cervical cancer cells, which might in turn reduce the sensitivity of these cells to cisplatin treatment. These findings uncovered the underlying mechanism and potential significance of SOX6-induced autophagy, and shed new light on the usage of MAP4K4 inhibitor or autophagy-specific inhibitor for sensitizing cervical cancer cells to the platinum-based chemotherapy.

HMG20A from Nile tilapia (Oreochromis niloticus) involved in the immune response to bacterial infection

High-mobility group 20 A (HMG20A) has important biological functions, such as inhibiting the differentiation of red blood cells and nerve cells, promoting the proliferation and metastasis of cancer cells, and regulating inflammatory reaction. However, the role of HMG20A in the response to bacterial infection in the economic fish Nile tilapia (Oreochromis niloticus) remains unclear. In this study, a HMG20A homolog was successfully identified and characterized from Nile tilapia (On-HMG20A), and its expression model and biological effects on bacterial infection were analyzed. The open reading frame (ORF) of On-HMG20A was 876 bp in length, which encoded 291 amino acids and possessed a HMG domain (High mobility group domains) and coiled coil region. Results of the expression model showed that On-HMG20A was widely distributed in immune-related tissues of healthy tilapia and upregulated in a time-dependent manner after being challenged by Streptococcus agalactiae. Meanwhile, knocking down the expression of On-HMG20A can reduce the inflammatory response of tilapia and the degree of tissue damage caused by S. agalactiae. Moreover, knocking down the expression of On-HMG20A can reduce the bacterial load of tilapia tissues after being challenged by S. agalactiae and improve the survival rate. Collectively, these results showed that On-HMG20A may be related to the immune response of Nile tilapia against bacterial infection.

Interaction of SOX5 with SOX9 promotes warfarin-induced aortic valve interstitial cell calcification by repressing transcriptional activation of LRP6

Calcific aortic valve disease (CAVD) is an important health burden due to its increasing prevalence and lack of available approaches. Osteogenic transdifferentiation of aortic valve interstitial cells (AVICs) contributes to valve calcification. SRY-related HMG-box transcription factor 5 (SOX5) is essential for cartilage development. Whether SOX5 is involved in AVIC calcification has not been determined. This study aimed to explore the role of SOX5 in warfarin-induced AVIC calcification. Immunostaining showed decreased SOX5 in human calcific AV and warfarin induced mouse calcific AV tissues compared with human noncalcific AV and control mouse AV tissues. In calcific human AVICs (hAVICs) and porcine AVICS (pAVICs), both knockdown and overexpression of SOX5 inhibited calcium deposition and osteogenic marker gene expression. Protein expression assays and ChIP assays showed that overexpression of SOX5 led to increased recruitment of SOX5 to the SOX9 promoter and resulted in increased mRNA and protein expression of SOX9. Coimmunoprecipitation and immunofluorescence showed that SOX5 binds to SOX9 with its HMG domain in nucleus. Blue Native PAGE showed overexpression of SOX5 led to multimeric complex formation of SOX5 and resulted in decreased binding of SOX5 to SOX9 similar to the results of knockdown of SOX5. Further ChIP and western blotting assays showed that both knockdown and overexpression of SOX5 resulted in SOX9 initiating transcription of anti-calcific gene LRP6 in warfarin-treated pAVICs. Knockdown of LRP6 rescues the anti-calcification effect of SOX5 overexpression. We found that both loss and gain of function of SOX5 lead to the same phenotype: decreased warfarin induced calcification. The stoichiometry of SOX5 is crucial for cooperation with SOX9, SOX9 nuclear localization and subsequent binding of SOX9 to LRP6 promoter. These results suggest that SOX5 is a potential target for the development of anti-calcification therapy.