Cardiac myogenesis: overexpression of XCsx2 or XMEF2A in whole Xenopus embryos induces the precocious expression of XMHCα gene

XCsx2 , a homeobox-containing gene, is expressed in cardiac muscle during Xenopus development, while the XMEF2A gene is expressed in both cardiac and skeletal muscle. Microinjection of either XCsx2 or XMEF2A mRNA into single blastomeres of two-cell stage Xenopus embryos induced precocious expression of the myosin heavy-chain alpha ( XMHC α) gene at the neural plate stage (stage 14). Co-injection of both XCsx2 and XMEF2A mRNAs induced still earlier expression at the late gastrula stage (stage 12). These changes were evident in whole embryos but not in animal pole explants from injected embryos. Overexpression of XCsx2 or XMEF2A also caused an enlarged heart and abnormalities of notochord and tail in Xenopus embryos. These findings suggest that both XCsx2 and XMEF2A transcription factors have an important role in regulating the expression of the XMHCα gene and the morphogenesis of heart tissue in Xenopus development.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47512/1/427_2004_Article_BF00357766.pd

Proinflammatory cytokine production and insulin sensitivity regulated by overexpression of resistin in 3T3-L1 adipocytes

Resistin is secreted from adipocytes, and high circulating levels have been associated with obesity and insulin resistance. To investigate whether resistin could exert autocrine effects in adipocytes, we expressed resistin gene in 3T3-L1 fibroblasts using a lentiviral vector, and selected several stably-transduced cell lines under blasticidin selection. We observed that 3T3-L1 adipocytes expressing resistin have a decreased gene expression for related transcriptional factors (CCAAT/enhancer binding protein α(C/EBPα) , peroxisome proliferator-activated receptor gamma (PPARγ), and adipocyte lipid binding protein (ALBP/aP2) which is one of target genes for the PPARγ during adipocyte differentiation,. Overexpression of resistin increased the levels of three proinflammatory cytokines, tumor necrosis factor alpha (TNFα), interleukin 6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), which play important roles for insulin resistance, glucose and lipid metabolisms during adipogenesis. Furthermore, overexpressing resistin in adipocytes inhibits glucose transport 4 (GLUT4) activity and its gene expression, reducing insulin's ability for glucose uptake by 30 %. In conclusion, resistin overexpression in stably transduced 3T3-L1 cells resulted in: 1) Attenuation of programmed gene expression responsible for adipogenesis; 2) Increase in expression of proinflammatory cytokines; 3) Decrease in insulin responsiveness of the glucose transport system. These data suggest a new role for resistin as an autocrine/paracrine factor affecting inflammation and insulin sensitivity in adipose tissue

Role of extrathyroidal TSHR expression in adipocyte differentiation and its association with obesity

<p>Abstract</p> <p>Background</p> <p>Obesity is known to be associated with higher risks of cardiovascular disease, metabolic syndrome, and diabetes mellitus. Thyroid-stimulating hormone (TSHR) is the receptor for thyroid-stimulating hormone (TSH, or thyrotropin), the key regulator of thyroid functions. The expression of TSHR, once considered to be limited to thyrocytes, has been so far detected in many extrathyroidal tissues including liver and fat. Previous studies have shown that TSHR expression is upregulated when preadipocytes differentiate into mature adipocytes, suggestive of a possible role of TSHR in adipogenesis. However, it remains unclear whether TSHR expression in adipocytes is implicated in the pathogenesis of obesity.</p> <p>Methods</p> <p>In the present study, TSHR expression in adipose tissues from both mice and human was analyzed, and its association with obesity was evaluated.</p> <p>Results</p> <p>We here showed that TSHR expression was increased at both mRNA and protein levels when 3T3-L1 preadipocytes were induced to differentiate. Knockdown of TSHR blocked the adipocyte differentiation of 3T3-L1 preadipocytes as evaluated by Oil-red-O staining for lipid accumulation and by RT-PCR analyses of PPAR-γ and ALBP mRNA expression. We generated obesity mice (C57/BL6) by high-fat diet feeding and found that the TSHR protein expression in visceral adipose tissues from obesity mice was significantly higher in comparison with the non-obesity control mice (<it>P </it>< 0.05). Finally, the TSHR expression in adipose tissues was determined in 120 patients. The results showed that TSHR expression in subcutaneous adipose tissue is correlated with BMI (body mass index).</p> <p>Conclusion</p> <p>Taken together, these results suggested that TSHR is an important regulator of adipocyte differentiation. Dysregulated expression of TSHR in adipose tissues is associated with obesity, which may involve a mechanism of excess adipogenesis.</p

Expression of Circular Plasmids Which Contain Bacterial Chloramphenicol Acetyltransferase Gene Connected to the Promotoer of Polypeptide IX Gene of Human Adenovirus Type 12 in Oocytes, Eggs and Embryos of Xenopus laevis : Cell Biology

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Effects of over-expression of TLR2 in transgenic goats on pathogen clearance and role of up-regulation of lysozyme secretion and infiltration of inflammatory cells

<p>Abstract</p> <p>Background</p> <p>Toll-like receptor 2 (TLR2) is important to host recognition of invading gram-positive microbes. In goats, these microbes can cause serious mastitis, anthrax, tetanus, and other problems. Transgenic goats constitutively over-expressing TLR2 in many tissues serve as a suitable model for the study of the role of TLR2 over-expression in bacterial clearance.</p> <p>Results</p> <p><it>Capra hircus</it> TLR2 over-expression vector (p3S-LoxP-TLR2) was used to generate transgenic goats by egg microinjection. The integration efficiency was 8.57%. Real-time PCR and immunohistochemical results confirmed that the goats over-expressing the TLR2 gene (Tg) expressed more TLR2 than wild-type goats (WT). Monocyte-macrophages from the bloodstreams of transgenic goats were stimulated with synthetic bacterial lipoprotein (Pam3CSK4) and by the promotion of interleukin-6 (IL-6) and IL-10 expression in vitro. The oxidative damage was significantly reduced, and lysozyme (LZM) secretion was found to be up-regulated. Ear tissue samples from transgenic goats that had been stimulated with Pam3CSK4 via hypodermic injection showed that transgenic individuals can undergo the inflammation response very quickly.</p> <p>Conclusions</p> <p>Over-expression of TLR2 was found to decrease radical damage to host cells through low-level production of NO and MDA and to promote the clearance of invasive bacteria by up-regulating lysozyme secretion and filtration of inflammatory cells to the infected site.</p