Secretoglobin 3A2 Exhibits Anti-Fibrotic Activity in Bleomycin-Induced Pulmonary Fibrosis Model Mice

Objective

Secretoglobin (SCGB) 3A2 is a novel lung-enriched cytokine, previously shown to exhibit anti-inflammatory, growth factor, and anti-fibrotic activities. The latter activity was demonstrated using exogenously-administered recombinant SCGB3A2 in the bleomycin (BLM)-induced pulmonary fibrosis model. Whether SCGB3A2 exhibits anti-fibrotic activity in vivo is not known.

Methods

Mice null for the Scgb3a2 gene were subjected to the BLM-induced pulmonary fibrosis model, and the severity of pulmonary fibrosis determined using histological and biochemical methods.

Results

BLM treatment caused weight loss of both Scgb3a2-null and wild-type mice, however, the loss was far more pronounced in BLM-treated Scgb3a2-null than wild-type mice, and the weight of day 21 of BLM-treated Scgb3a2-null mice was about half of that of BLM-treated wild-type mice. Hematoxylin & Eosin, Masson Trichrome, and Sirius Red staining of lung sections, Ashcroft fibrosis scores, hydroxyproline contents, and the levels of mRNAs encoding various collagens demonstrated that BLM-treated Scgb3a2-null mouse lungs had more severe fibrosis than those of wild-type mouse lungs. Total and differential inflammatory cell numbers in bronchoalveolar lavage fluids, and levels of lung mRNAs including those encoding Th2 cytokines such as IL-4 and profibrotic cytokines such as TGFβ were higher in BLM-treated Scgb3a2-null mouse lungs as compared to those of wild-type mouse lungs. In contrast, mRNAs encoding surfactant proteins A, B, C, and D, and SCGB1A1 did not differ between BLM-treated Scgb3a2-null and wild-type mouse lungs.

Conclusion

The role of SCGB3A2 in fibrosis was revisited using Scgb3a2-null mice and littermate controls in the BLM-induced pulmonary fibrosis model. The pulmonary fibrosis in the Scgb3a2-null mice was more severe than the wild-type controls, thus establishing that SCGB3A2 has anti-fibrotic activity in vivo. Importantly, surfactant proteins and SCGB1A1 appear not to be involved in the susceptibility of Scgb3a2-null mice to BLM-induced pulmonary fibrosis.     

The gene structure and expression of human ABHD1: overlapping polyadenylation signal sequence with Sec12

Background

Overlapping sense/antisense genes orientated in a tail-to-tail manner, often involving only the 3'UTRs, form the majority of gene pairs in mammalian genomes and can lead to the formation of double-stranded RNA that triggers the destruction of homologous mRNAs. Overlapping polyadenylation signal sequences have not been described previously.

Results

An instance of gene overlap has been found involving a shared single functional polyadenylation site. The genes involved are the human alpha/beta hydrolase domain containing gene 1 (ABHD1) and Sec12 genes. The nine exon human ABHD1 gene is located on chromosome 2p23.3 and encodes a 405-residue protein containing a catalytic triad analogous to that present in serine proteases. The Sec12 protein promotes efficient guanine nucleotide exchange on the Sar1 GTPase in the ER. Their sequences overlap for 42 bp in the 3'UTR in an antisense manner. Analysis by 3' RACE identified a single functional polyadenylation site, ATTAAA, within the 3'UTR of ABHD1 and a single polyadenylation signal, AATAAA, within the 3'UTR of Sec12. These polyadenylation signals overlap, sharing three bp. They are also conserved in mouse and rat. ABHD1 was expressed in all tissues and cells examined, but levels of ABHD1 varied greatly, being high in skeletal muscle and testis and low in spleen and fibroblasts.

Conclusions

Mammalian ABHD1 and Sec12 genes contain a conserved 42 bp overlap in their 3'UTR, and share a conserved TTTATTAAA/TTTAATAAA sequence that serves as a polyadenylation signal for both genes. No inverse correlation between the respective levels of ABHD1 and Sec12 RNA was found to indicate that any RNA interference occurred.     

The experience of brace treatment in children/adolescents with scoliosis

Background

In a previous study, a number of genes, associated with spine musculoskeletal deformity phenotypes in mouse and in synteny between mouse and man, were identified as candidate genes for IS. Among these genes, MATN 1, which carries a polymorphic microsatellite marker within its sequence, was selected for a linkage analysis. MATN1 is localised at 1p35 and is mainly expressed in cartilage. The objective of this study was to assess a linkage disequilibrium between the matrilin-1 (MATN 1) gene and the idiopathic scoliosis (IS).

Methods

The genetic study was conducted on a population of 81 trios, each consistent of a daughter/son affected by idiopathic scoliosis (IS) and both parents. In all trios components, the region of MATN1 gene containing the microsatellite marker was amplified by a polymerase chain reaction. The amplicons were analysed by a DNA sequencer-genotyper. The statistical linkage analysis was performed using the extended transmission/disequilibrium test.

Results

Three microsatellite polymorphisms, respectively consisting of 103 bp, 101 bp and 99 bp, were identified. ETDT evidenced a significant preferential transmission for the 103 bp allele (Chi-square = 5.058, df = 1, P = 0.024)

Conclusion

The results suggest that the familial idiopathic scoliosis is associated to the MATN1 gene.     

Stability of gene expression and epigenetic profiles highlights the utility of patient-derived paediatric acute lymphoblastic leukaemia xenografts for investigating molecular mechanisms of drug resistance

Background

Patient-derived tumour xenografts are an attractive model for preclinical testing of anti-cancer drugs. Insights into tumour biology and biomarkers predictive of responses to chemotherapeutic drugs can also be gained from investigating xenograft models. As a first step towards examining the equivalence of epigenetic profiles between xenografts and primary tumours in paediatric leukaemia, we performed genome-scale DNA methylation and gene expression profiling on a panel of 10 paediatric B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) tumours that were stratified by prednisolone response.

Results

We found high correlations in DNA methylation and gene expression profiles between matching primary and xenograft tumour samples with Pearson’s correlation coefficients ranging between 0.85 and 0.98. In order to demonstrate the potential utility of epigenetic analyses in BCP-ALL xenografts, we identified DNA methylation biomarkers that correlated with prednisolone responsiveness of the original tumour samples. Differential methylation of CAPS2, ARHGAP21, ARX and HOXB6 were confirmed by locus specific analysis. We identified 20 genes showing an inverse relationship between DNA methylation and gene expression in association with prednisolone response. Pathway analysis of these genes implicated apoptosis, cell signalling and cell structure networks in prednisolone responsiveness.

Conclusions

The findings of this study confirm the stability of epigenetic and gene expression profiles of paediatric BCP-ALL propagated in mouse xenograft models. Further, our preliminary investigation of prednisolone sensitivity highlights the utility of mouse xenograft models for preclinical development of novel drug regimens with parallel investigation of underlying gene expression and epigenetic responses associated with novel drug responses.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-416) contains supplementary material, which is available to authorized users.