Isolation and molecular characterization of the porcine transforming growth factor beta type I receptor (TGFBR1) gene

Species-specific sensitivity to TGFβ signaling and changes to the Mmp13 promoter underlie avian jaw development and evolution

Precise developmental control of jaw length is critical for survival, but underlying molecular mechanisms remain poorly understood. The jaw skeleton arises from neural crest mesenchyme (NCM), and we previously demonstrated that these progenitor cells express more bone-resorbing enzymes including Matrix metalloproteinase 13 (Mmp13) when they generate shorter jaws in quail embryos versus longer jaws in duck. Moreover, if we inhibit bone resorption or Mmp13, we can increase jaw length. In the current study, we uncover mechanisms establishing species-specific levels of Mmp13 and bone resorption. Quail show greater activation of and sensitivity to transforming growth factor beta (TGFβ) signaling than duck; where intracellular mediators like SMADs and targets like Runt-related transcription factor 2 (Runx2), which bind Mmp13, become elevated. Inhibiting TGFβ signaling decreases bone resorption, and overexpressing Mmp13 in NCM shortens the duck lower jaw. To elucidate the basis for this differential regulation, we examine the Mmp13 promoter. We discover a SMAD-binding element and single nucleotide polymorphisms (SNPs) near a RUNX2-binding element that distinguish quail from duck. Altering the SMAD site and switching the SNPs abolish TGFβ sensitivity in the quail Mmp13 promoter but make the duck promoter responsive. Thus, differential regulation of TGFβ signaling and Mmp13 promoter structure underlie avian jaw development and evolution.

Molecular cloning and characteristics analysis of Pmtgfbr1 from Pinctada fucata martensii

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This study obtains the full length of Pmtgfbr1 of the pearl oyster P. fucata martensii.

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Pmtgfbr1 possesses the conserved domain of Tgfbr1.

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Pmtgfbr1 holds negatively effect on the growth of P. fucata martensii.

Pinctada fucata martensii is cultured for pearl production. Growth improvement has received considerable research interest. Transforming growth factor β type Ⅰ receptor (TβR-I), which is involved in signals transmission of transforming growth factor beta (TGF-β), participates in cell proliferation and growth. In this study, we characterized a Tgfbr1 gene which encoded TβR-I from P. fucata martensii (Pmtgfbr1). Pmtgfbr1 cDNA contains an open reading frame of 1569 bp and encodes a polypeptide of 522 amino acids (aa). Pmtgfbr1 possesses a typical TβR-I structure (extracellular receptor ligand domain, transmembrane domain, and cytoplasmic tyrosine kinase catalytic domain). Pmtgfbr1 is expressed in all the studied tissues and exhibited the highest expression level in the adductor muscle. Moreover, Pmtgfbr1 exhibited the lower expression level in the larger group (L) than that in the smaller group (S) and is negatively correlated with growth traits (P < 0.01). Our results indicated that Pmtgfbr1 is a candidate functional gene associated with growth traits.

Dysregulated microRNA clusters in response to retinoic acid and CYP26B1 inhibitor induced testicular function in dogs

Spermatogenesis is a multistep synchronized process. Diploid spermatogonia differentiate into haploid spermatozoa following mitosis, meiosis and spermiogenesis. Division and differentiation of male germ cells is achieved through the sequential expression of several genes. Numerous mRNAs in the differentiating germ cells undergo post-transcriptional and translational regulation. MiRNAs are powerful negative regulators of mRNA transcription, stability, and translation and recognize their mRNA targets through base-pairing. Retinoic acid (RA) signaling is essential for spermatogenesis and testicular function. Testicular RA level is critical for RA signal transduction. This study investigated the miRNAs modulation in an RA- induced testicular environment following the administration of all-trans RA (2 µM) and CYP26B1- inhibitor (1 µM) compared to control. Eighty four canine mature miRNAs were analyzed and their expression signatures were distinguished using real-time PCR based array technology. Of the miRNAs analyzed, miRNA families such as miR-200 (cfa-miR-200a, cfa-miR-200b and cfa-miR-200c), Mirlet-7 (cfa-let-7a, cfa-let-7b, cfa-let-7c, cfa-let-7g and cfa-let-7f), miR-125 (cfa-miR-125a and cfa-miR-125b), miR-146 (cfa-miR-146a and cfa-miR-146b), miR-34 (cfa-miR-34a, cfa-miR-34b and cfa-miR-34c), miR-23 (cfa-miR-23a and cfa-miR-23b), cfa-miR-184, cfa-miR-214 and cfa-miR-141 were significantly up-regulated with testicular RA intervention via administration of CYP26B1 inhibitor and all-trans-RA and species of miRNA such as cfa-miR-19a, cfa-miR-29b, cfa-miR-29c, cfa-miR-101 and cfa-miR-137 were significantly down-regulated. This study explored information regarding chromosome distribution, human orthologous sequences and the interaction of target genes of miRNA families significantly distinguished in this study using prediction algorithms. This study importantly identified dysregulated miRNA species resulting from RA-induced spermatogenesis. The present contribution serves as a useful resource for further elucidation of the regulatory role of individual miRNA in RA synchronized canine spermatogenesis.

Splicing variants of the porcine betaine-homocysteine S-methyltransferase gene: implications for mammalian metabolism

Betaine-homocysteine S-methyltransferase (BHMT) activity is only detected in the liver of rodents, but in both the liver and kidney cortex of humans and pigs; therefore, the pig was chosen as a model to define the spatial and temporal expression of BHMT during development. During fetal development, a total of ten splice variants of bhmt were expressed at varying levels across a wide range of porcine tissues. Two variants contained an identical ORF that encoded a C-terminal truncated form of BHMT (tBHMT). The bhmt transcripts were expressed at significant levels in the liver and kidney from day 45 of gestation (G45) onward. The transcripts encoding tBHMT represented 5-13% of the total bhmt transcripts in G30 fetus, G45 liver, and adult liver and kidney cortex. The dominant structural feature of wild type BHMT is an (βα)8 barrel, however, a modeled structure of tBHMT suggests that this protein would assume a horseshoe fold and lack methyltransferase activity. Low BHMT activity was detected in the G30 fetus, and slightly increased levels of activity were observed in the liver from G45 and G90 fetuses. The bhmt promoter contained three key CpG sites, and methylation of these sites was significantly higher in adult lung compared to adult liver. The data reported herein suggest that genomic DNA methylation and variation of the 5' and 3' UTRs of bhmt transcripts are key regulators for the level of BHMT transcription and translation.

Transforming growth factor-β signalling: role and consequences of Smad linker region phosphorylation

Transforming growth factor-β (TGF-β) is a secreted homodimeric protein that plays an important role in regulating various cellular responses including cell proliferation and differentiation, extracellular matrix production, embryonic development and apoptosis. Disruption of the TGF-β signalling pathway is associated with diverse disease states including cancer, renal and cardiac fibrosis and atherosclerosis. At the cell surface TGF-β complex consists of two type I and two type II transmembrane receptors (TβRI and TβRII respectively) which have serine/threonine kinase activity. Upon TGF-β engagement TβRII phosphorylates TβRI which in turn phosphorylates Smad2/3 on two serine residues at their C-terminus which enables binding to Smad4 to form heteromeric Smad complexes that enter the nucleus to initiate gene transcription including for extracellular matrix proteins. TGF-β signalling is also known to activate other serine/threonine kinase signalling that results in the phosphorylation of the linker region of Smad2. The Smad linker region is defined as the domain which lies between the MH1 and MH2 domains of a Smad protein. Serine/threonine kinases that are known to phosphorylate the Smad linker region include mitogen-activated protein kinases, extracellular-signal regulated kinase, Jun N-terminal kinase and p38 kinase, the tyrosine kinase Src, phosphatidylinositol 3'-kinase, cyclin-dependent kinases, rho-associated protein kinase, calcium calmodulin-dependent kinase and glycogen synthase kinase-3. This review will cover the role of Smad linker region phosphorylation downstream of TGF-β signalling in vascular cells. Key factors including the identification of the kinases that phosphorylate individual Smad residues, the upstream agents that activate these kinases, the cellular location of the phosphorylation event and the importance of the linker region in regulation and expression of genes induced by TGF-β are covered.

Modulation of systemic immune responses through commensal gastrointestinal microbiota

Colonization of the gastrointestinal (GI) tract is initiated during birth and continually seeded from the individual's environment. Gastrointestinal microorganisms play a central role in developing and modulating host immune responses and have been the subject of investigation over the last decades. Animal studies have demonstrated the impact of GI tract microbiota on local gastrointestinal immune responses; however, the full spectrum of action of early gastrointestinal tract stimulation and subsequent modulation of systemic immune responses is poorly understood. This study explored the utility of an oral microbial inoculum as a therapeutic tool to affect porcine systemic immune responses. For this study a litter of 12 pigs was split into two groups. One group of pigs was inoculated with a non-pathogenic oral inoculum (modulated), while another group (control) was not. DNA extracted from nasal swabs and fecal samples collected throughout the study was sequenced to determine the effects of the oral inoculation on GI and respiratory microbial communities. The effects of GI microbial modulation on systemic immune responses were evaluated by experimentally infecting with the pathogen Mycoplasma hyopneumoniae. Coughing levels, pathology, toll-like receptors 2 and 6, and cytokine production were measured throughout the study. Sequencing results show a successful modulation of the GI and respiratory microbiomes through oral inoculation. Delayed type hypersensitivity responses were stronger (p = 0.07), and the average coughing levels and respiratory TNF-α variance were significantly lower in the modulated group (p<0.0001 and p = 0.0153, respectively). The M. hyopneumoniae infection study showed beneficial effects of the oral inoculum on systemic immune responses including antibody production, severity of infection and cytokine levels. These results suggest that an oral microbial inoculation can be used to modulate microbial communities, as well as have a beneficial effect on systemic immune responses as demonstrated with M. hyopneumoniae infection.

Molecular characterization of TGF-β type I receptor gene (Tgfbr1) in Chlamys farreri, and the association of allelic variants with growth traits

BACKGROUND

Scallops are an economically important aquaculture species in Asian countries, and growth-rate improvement is one of the main focuses of scallop breeding. Investigating the genetic regulation of scallop growth could benefit scallop breeding, as such research is currently limited. The transforming growth factor beta (TGF-β) signaling through type I and type II receptors, plays critical roles in regulating cell proliferation and growth, and is thus a plausible candidate growth regulator in scallops.

RESULTS

We cloned and characterized the TGF-β type I receptor (Tgfbr1) gene from Zhikong scallops (Chlamys farreri). The deduced amino acid sequence contains characteristic residues and exhibits the conserved structure of Tgfbr1 proteins. A high expression level of scallop Tgfbr1 was detected during early embryonic stages, whereas Tgfbr1 expression was enriched in the gonad and striated muscle in adults. A single nucleotide polymorphism (SNP, c. 1815C>T) in the 3' UTR was identified. Scallops with genotype TT had higher growth traits values than those with genotype CC or CT in a full-sib family, and significant differences were found between genotypes CC and TT for shell length, shell height, and striated muscle weight. An expression analysis detected significantly more Tgfbr1 transcripts in the striated muscle of scallops with genotype CC compared to those with genotype TT or CT. Further evaluation in a population also revealed higher striated muscle weight in scallops with genotype TT than those with the other two genotypes. The inverse correlation between striated muscle mass and Tgfbr1 expression is consistent with TGF-β signaling having a negative effect on cell growth.

CONCLUSION

The scallop Tgfbr1 gene was cloned and characterized, and an SNP potentially associated with both scallop growth and Tgfbr1 expression was identified. Our results suggest the negative regulation of Tgfbr1 in scallop growth and provide a candidate marker for Zhikong scallop breeding.

Association of the porcine transforming growth factor beta type I receptor (TGFBR1) gene with growth and carcass traits

BACKGROUND

Growth and carcass traits are of great economic importance in livestock production. A large number of quantitative trait loci (QTL) have been identified for growth and carcass traits on porcine chromosome one (SSC1). A key positional candidate for this chromosomal region is TGFBR1 (transforming growth factor beta type I receptor). This gene plays a key role in inherited disorders at cardiovascular, craniofacial, neurocognitive, and skeletal development in mammals.

RESULTS

In this study, 27 polymorphic SNPs in the porcine TGFBR1 gene were identified on the University of Illinois Yorkshire × Meishan resource population. Three SNPs (SNP3, SNP43, SNP64) representing major polymorphic patterns of the 27 SNPs in F1 and F0 individuals of the Illinois population were selected for analyses of QTL association and genetic diversity. An association analysis for growth and carcass traits was completed using these three representative SNPs in the Illinois population with 298 F2 individuals and a large commercial population of 1008 animals. The results indicate that the TGFBR1 gene polymorphism (SNP64) is significantly associated (p < 0.05) with growth rates including average daily gains between birth and 56 kg (p = 0.049), between 5.5 and 56 kg (p = 0.024), between 35 and 56 kg (p = 0.021). Significant associations (p < 0.05) were also identified between TGFBR1 gene polymorphisms (SNP3/SNP43) and carcass traits including loin-eye-area (p = 0.022) in the Illinois population, and back-fat thickness (p = 0.0009), lean percentage (p = 0.0023) and muscle color (p = 0.021) in the commercial population. These three SNPs were also used to genotype a diverse panel of 130 animals representing 11 pig breeds. Alleles SNP3_T and SNP43_G were fixed in Pietrain and Sinclair pig breeds. SNP64_G allele was uniquely identified in Chinese Meishan pigs. Strong evidence of association (p < 0.01) between both SNP3 and SNP64 alleles and reproductive traits including gestation length and number of corpora lutea were also observed in the Illinois population.

CONCLUSION

This study gives the first evidence of association between the porcine TGFBR1 gene and traits of economic importance and provides support for using TGFBR1 markers for pig breeding and selection programs. The genetic diversities in different pig breeds would be helpful to understand the genetic background and migration of the porcine TGFBR1 gene.

Molecular characterization and analysis of the porcine betaine homocysteine methyltransferase and betaine homocysteine methyltransferase-2 genes

Betaine homocysteine methyltransferase (BHMT) and BHMT-2 enzymes methylate homocysteine to form methionine using betaine and S-methylmethionine, respectively. These activities are observed only in the liver of adult rodents, but in adult humans and pigs these activities are detected in both the liver and kidney, indicating the pig is a more appropriate model for studying the biochemical and physiological roles of these enzymes in human biology. Porcine BHMT and BHMT-2 cDNAs were cloned and sequenced, and their 5' and 3' UTR were amplified using RLM-RACE. The BHMT transcript had significantly longer 5' and 3' UTRs than BHMT-2. The pig BHMT and BHMT-2 genes span approximately 26 and 16kb, respectively, and both genes have 8 exons. The deduced amino acid sequences of BHMT and BHMT-2 contain 407 and 363 amino acids, respectively, and shared 78% amino acid identity. No promoter element (TATA or CAAT box) was observed for either BHMT or BHMT-2, although a CpG island surrounding the promoter and transcriptional start site was observed in both genes implying that methylation could regulate their expression. Using qPCR, it was determined that BHMT and BHMT-2 transcripts are very abundant in liver and kidney cortex, whereas the expression is significantly less in other tissues. These findings confirm that the expression pattern of BHMT and BHMT-2 genes in pigs is similar to humans, supporting the use of the pig as an animal model to study the genetics and regulation of BHMT and BHMT-2 expression.

Modeling bone marrow toxicity using kinase structural motifs and the inhibition profiles of small molecular kinase inhibitors

The cellular function of kinases combined with the difficulty of designing selective small molecule kinase inhibitors (SMKIs) poses a challenge for drug development. The late-stage attrition of SMKIs could be lessened by integrating safety information of kinases into the lead optimization stage of drug development. Herein, a mathematical model to predict bone marrow toxicity (BMT) is presented which enables the rational design of SMKIs away from this safety liability. A specific example highlights how this model identifies critical structural modifications to avoid BMT. The model was built using a novel algorithm, which selects 19 representative kinases from a panel of 277 based upon their ATP-binding pocket sequences and ability to predict BMT in vivo for 48 SMKIs. A support vector machine classifier was trained on the selected kinases and accurately predicts BMT with 74% accuracy. The model provides an efficient method for understanding SMKI-induced in vivo BMT earlier in drug discovery.

Alternative splicing of TGF-betas and their high-affinity receptors T beta RI, T beta RII and T beta RIII (betaglycan) reveal new variants in human prostatic cells

Background

The transforming growth factors (TGF)-β, TGF-β1, TGF-β2 and TGF-β3, and their receptors [TβRI, TβRII, TβRIII (betaglycan)] elicit pleiotropic functions in the prostate. Although expression of the ligands and receptors have been investigated, the splice variants have never been analyzed. We therefore have analyzed all ligands, the receptors and the splice variants TβRIB, TβRIIB and TGF-β2B in human prostatic cells.

Results

Interestingly, a novel human receptor transcript TβRIIC was identified, encoding additional 36 amino acids in the extracellular domain, that is expressed in the prostatic cancer cells PC-3, stromal hPCPs, and other human tissues. Furthermore, the receptor variant TβRIB with four additional amino acids was identified also in human. Expression of the variant TβRIIB was found in all prostate cell lines studied with a preferential localization in epithelial cells in some human prostatic glands. Similarly, we observed localization of TβRIIC and TGF-β2B mainly in the epithelial cells with a preferential localization of TGF-β2B in the apical cell compartment. Whereas in the androgen-independent hPCPs and PC-3 cells all TGF-β ligands and receptors are expressed, the androgen-dependent LNCaP cells failed to express all ligands. Additionally, stimulation of PC-3 cells with TGF-β2 resulted in a significant and strong increase in secretion of plasminogen activator inhibitor-1 (PAI-1) with a major participation of TβRII.

Conclusion

In general, expression of the splice variants was more heterogeneous in contrast to the well-known isoforms. The identification of the splice variants TβRIB and the novel isoform TβRIIC in man clearly contributes to the growing complexity of the TGF-β family.