Transcriptional regulation of the HOX4C gene by basic fibroblast growth factor on rheumatoid synovial fibroblasts

Inhibition of HOXD11 promotes cartilage degradation and induces osteoarthritis development

The 5'-HOXD genes are important for chondrogenesis in vertebrates, but their roles in osteoarthritis (OA) are still ambiguous. In our study, 5'-HOXD genes involvement contributing to cartilage degradation and OA was investigated. In bioinformatics analysis of 5'-HOXD genes, we obtained the GSE169077 data set related to OA in the GEO and analyzed DEGs using the GEO2R tool attached to the GEO. Then, we screened the mRNA levels of 5'-HOXD genes by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). We discovered that OA chondrocyte proliferation was inhibited, and apoptosis was increased. Moreover, it was discovered that SOX9 and COL2A1 were downregulated at mRNA and protein levels, while matrix metalloproteinases (MMPs) and a disintegrin-like and metalloproteinase with thrombospondin motifs (ADAMTSs) were upregulated. According to the results of differentially expressed genes (DEGs) and qRT-PCR, we evaluated the protein level of HOXD11 and found that the expression of HOXD11 was downregulated, reversed to MMPs and ADAMTSs but consistent with the cartilage-specific factors, SOX9 and COL2A1. In the lentivirus transfection experiments, HOXD11 overexpression reversed the effects in OA chondrocytes. In human OA articular cartilage, aberrant subchondral bone was formed in hematoxylin-eosin (H&E) and Safranin O and fast green (SOFG) staining results. Furthermore, according to immunohistochemistry findings, SOX9 and HOXD11 expression was inhibited. The results of this study established that HOXD11 was downregulated in OA cartilage and that overexpression of HOXD11 could prevent cartilage degradation in OA.

Does brachydactyly have a protective effect on the erosive changes in rheumatoid arthritis?

OBJECTIVE

Brachydactyly (BD) is a general term for inappropriately short fingers and/or toes. The author previously reported that a short metacarpal bone had a protective effect on the metacarpophalangeal joint of the same finger in rheumatoid arthritis (RA). The objective was to investigate the prevalence of BD in patients with RA and its potential effect on the phenotype, especially erosive changes.

METHODS

A total of 1524 Korean patients with RA were recruited. The presence of BD on hand radiographs, rheumatoid factor (RF), anti-cyclic citrullinated peptide antibody (anti-CCP), HLA-DRB1 shared epitopes (SE), risk haplotypes of peptidyl deiminase type IV (PADI4) and erosive joint stage, and smoking status, were determined.

RESULTS

The prevalence of BD was 7.9% (n=120) in our RA cohort. The types of BD were type A3 (79.2%), type D (15.0%), Kirner deformity (14.2%), and type E (6.7%). RA patients with BD had reduced erosion on hand radiographs (OR=0.57, 95% CI: 0.34-0.95, p=0.029) adjusted for age, sex, disease duration, smoking, RF, anti-CCP, SE, and PADI4.

CONCLUSION

BD is more common in RA patients than might be expected. BD may have a protective effect on erosive changes in RA independent of previously well-established risk factors such as seropositivity, SE, PADI4, and smoking.

Epigenetic deregulation in rheumatoid arthritis

In this chapter, we discuss the current understanding of the possible epigenetics changes that occur in rheumatoid arthritis. In particular, we describe that deregulation ofDNA methylation and histone modifications can occur in the immune system and lead to rheumatoid arthritis. In addition, we discuss the role of rheumatoid arthritis synovial fibroblasts in autoimmunity. Examples of changes in DNA methylation and histone modification occurring in synovial fibroblasts during the disease process are reviewed in this chapter. In conclusion, we discuss the possible use of epigenetic therapy and describe future experiments that can elucidate further the epigenetic changes observed in the disease.

Expression of homeobox genes in cervical cancer

OBJECTIVE

Members of the homeobox (HB) gene superfamily encode transcription factors crucial for development and may be associated with tumorigenesis. In this study, we aimed to develop a procedure to survey the expression of the dispersed-type HB genes in cervical cancer cells.

METHODS

Nineteen sets of degenerate primers were designed based on conserved homeodomains of known dispersed-type HB genes. A cDNA library derived from HeLa, a cervical cancer cell line, was used. Two successive rounds of PCR were performed using a combination of the HB degenerate primers and a primer recognizing the flanking sequence of the vector used in the cDNA library construction.

RESULTS

On cloning and sequence analysis of the PCR fragments generated, 10 known and 3 putative novel HB genes were detected in HeLa. RT-PCR expression analysis further showed that HOXD9 and ATBF1 were differentially expressed in cancer cells and not in normal cervix.

CONCLUSIONS

Our data demonstrate the feasibility of using degenerate primers in PCR experiments in a collective analysis of complex gene families. Our data indicate that HOXD9 and ATBF1 are expressed in cervical cancer, but not in normal cervix.

The genetics of the target tissue in rheumatoid arthritis

The genetic mechanisms that are complementary in predisposing and then establishing disease are yet to be fully elucidated. During a lifetime, the genetic composition of the host is not only hereditary but undergoes rearrangements, integrations, and more subtle single-base pair alterations. These changes can be inconsequential or lead to aberrant and deleterious pathologic changes. In a complex multifactorial disease such as RA, the relative roles of the dynamic versus germline elements of the disease have yet to be fully determined. Further studies of large populations are likely to segregate out factors affecting specific ethnic, clinical, and genetic subgroups.

Potential role ofHOXD9 in synoviocyte proliferation

OBJECTIVE

To investigate the role of HOXD9 in the proliferation activity of cultured synoviocytes as well as the mechanisms that regulate HOXD9 transcription.

METHODS

Synoviocytes from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) were transfected with HOXD9 complementary DNA to establish stable transformants that overexpressed HOXD9. HOXD9 expression was detected by Western blotting with anti-HOXD9 antibody. The growth properties of the transformants were investigated by proliferation and colony formation assays. The expression of basic fibroblast growth factor (bFGF), tumor necrosis factor alpha (TNFalpha), interleukin-1beta, c-Fos, and c-Myc was examined by Western blotting. Transcriptional regulation of HOXD9 was examined by transient cotransfection.

RESULTS

HOXD9 protein was highly expressed in RA synoviocytes, but there was no expression in OA synoviocytes. HOXD9 transfection induced stable HOXD9 protein expression in synoviocytes and showed an increased proliferation rate under both normal and serum-starved conditions, as well as an enhanced capacity to proliferate anchorage independently to form colonies in soft agar cultures, compared with control transfectants. Higher levels of bFGF and c-Fos were detected in HOXD9 transformants than in controls. Transient cotransfection assays of NIH3T3 fibroblasts and synoviocytes showed that HOXD9 activated the luciferase reporter construct containing the highly conserved region (HCR), an autoregulatory element of HOXD9 promoter. This activation was significantly increased by bFGF, suppressed by TNFalpha, and unchanged by transforming growth factor beta in synoviocytes. Human T lymphotropic virus type I tax also activated the luciferase reporter construct containing the HCR and had a synergistic effect with HOXD9 on HCR promoter activation.

CONCLUSION

Our data suggest that HOXD9 plays a potential role in synovial proliferation. In addition, they suggest that the involvement of HOXD9 in the regulation of cellular growth might be mediated, at least in part, by up-regulation of growth-related factors such as bFGF and c-Fos and/or might result from increased transcription activity by its regulators.

Expression of murine HOXD9 during embryonic joint patterning and in human T lymphotropic virus type I tax transgenic mice with arthropathy resembling rheumatoid arthritis

OBJECTIVE

To characterize the expression of murine HOXD9 during normal joint development and in arthritic joints of human T lymphotropic virus type I (HTLV-I) tax transgenic mice and the role of HTLV-I tax in HOXD9 expression.

METHODS

Expression of HOXD9, HOXD1O, HOXD11, HOXD12, and HOXD13 genes in joint tissues at the ankle/foot regions of mouse embryos at day 10 to day 18 of gestation (E10-E18) and neonates within 10 days after birth was determined by reverse transcriptase-polymerase chain reaction and in situ reverse transcription methods. Adult synovial tissues from 5 HTLV-I tax transgenic mice with chronic polyarthritis and 4 nontransgenic (normal) mice were also examined for expression of these HOXD genes. The effect of HTLV-I on HOXD9 expression in cultured synoviocytes was studied by in vitro infection and transfection experiments.

RESULTS

Expression of HOXD9 was detected in embryonic joints, preferentially on articular cartilage, only during the early stages of joint development (up to E15), whereas other HOXD genes were expressed throughout the embryonic and neonatal stages. In adult mice, transcripts of HOXD9 were specifically detected in synovial tissues from 4 of 5 arthritic mice, especially in the lining and sublining synovial cells, but not in synovial tissues of normal mice. Activation of HOXD9 was observed in cultured synoviocytes infected with HTLV-I in vitro as well as in those transfected with HTLV-I tax.

CONCLUSION

Our findings suggest that HOXD9 is involved not only in the early stages of normal joint development, but may also be involved in the pathologic process of arthritis. HTLV-I tax appeared as an activator of this HOX gene in cultured synoviocytes.