Comparison of transcriptome responses of the liver, tail fin, and olfactory epithelium of Rana [Lithobates] catesbeiana tadpoles disrupted by thyroid hormones and estrogen.

Thyroid hormones (THs) are important developmental regulators in vertebrates, including during the metamorphosis of a tadpole into a frog. Metamorphosis is a post-embryonic developmental period initiated by TH production in the tadpole thyroid gland. The two main bioactive forms of TH are L-thyroxine (T4) and 3,5,3'-triiodothyronine (T3); these hormones have overlapping but distinct mechanisms of action. Premetamorphic tadpoles are highly responsive to TH and can be induced to metamorphose through exogenous TH exposure, making them an important model for both the study of vertebrate TH signaling and endocrine disrupting chemicals (EDCs). It is important to differentiate TH-mediated responses from estrogenic responses in premetamorphic tadpoles when assessing dysregulation by EDCs as crosstalk between the two endocrine systems is well-documented. Herein, we compare the RNA-sequencing-derived transcriptomic profiles of three TH-responsive tissues (liver, olfactory epithelium, and tail fin) in premetamorphic bullfrog (Rana [Lithobates] catesbeiana) tadpoles exposed to T3, T4, and estradiol (E2). These profiles were generated using the latest available genome assembly for the species. The data indicate that there is a clear distinction, and little overlap, between the transcriptomic responses elicited by E2 and the THs. In contrast, within the THs, the T3- and T4-induced transcriptomic profiles generally show considerable overlap; however, the degree of overlap is highly tissue-dependent, illustrating the importance of distinguishing the two THs and the affected signaling pathways within the target tissue type when evaluating hormone active agents. The data herein also show that E2 and TH treatment can uniquely induce significant changes in expression of their respective "classic" bioindicator transcripts vtg (E2) and thra, thrb, and thibz (THs). However, care must be taken in the interpretation of increased vep or esr1 transcripts as a change in transcript levels can be induced by THs rather than solely E2.

Escherichia coli recombinant expression of SARS-CoV-2 protein fragments.

We have developed a method for the inexpensive, high-level expression of antigenic protein fragments of SARS-CoV-2 proteins in Escherichia coli. Our approach uses the thermophilic family 9 carbohydrate-binding module (CBM9) as an N-terminal carrier protein and affinity tag. The CBM9 module was joined to SARS-CoV-2 protein fragments via a flexible proline-threonine linker, which proved to be resistant to E. coli proteases. Two CBM9-spike protein fragment fusion proteins and one CBM9-nucleocapsid fragment fusion protein largely resisted protease degradation, while most of the CBM9 fusion proteins were degraded at some site in the SARS-CoV-2 protein fragment. All of the fusion proteins were highly expressed in E. coli and the CBM9-ID-H1 fusion protein was shown to yield 122 mg/L of purified product. Three purified CBM9-SARS-CoV-2 fusion proteins were tested and found to bind antibodies directed to the appropriate SARS-CoV-2 antigenic regions. The largest intact CBM9 fusion protein, CBM9-ID-H1, incorporates spike protein amino acids 540-588, which is a conserved region overlapping and C-terminal to the receptor binding domain that is widely recognized by human convalescent sera and contains a putative protective epitope.

Temperature-sensitive recombinant subtilisin protease variants that efficiently degrade molecular biology enzymes.

We used error-prone PCR to generate mutations in a subtilisin protease-encoding gene, and screened for recombinants that expressed temperature-sensitive (TS) variants. From the dozens of mutations that we detected in the recombinant genes we found that those mutations that affected aspartate-75 had the most profound effect on temperature stability. We thus focused our analysis on two variants of subtilisin C, the more heat-sensitive variant 24 (V24), with amino acid changes D75G, L234M and Q274P; and variant 25 (V25), with a single amino acid change, D75A. For V24 a two log-fold reduction in activity occurs in under 10 min at 50°C. For V25, a two log-fold reduction occurs at 60°C, a temperature that reduces the activity of the wild type enzyme by about 30%. The V24 variant fully inactivates enzymes commonly used in molecular biology research and in molecular diagnostics, and is stabilized against autolysis with propylene glycol concentrations of 10% or greater. The subtilisin variants are produced by a strain of Bacillus subtilis that lacks expression of its native secreted proteases, and the variants can be isolated from the supernatants using nickel affinity chromatography.

Interaction of silver nanoparticles with tethered bilayer lipid membranes.

Silver nanoparticles are well-known for their antibacterial properties. However, the detailed mechanism describing the interaction between the nanoparticles and a cell membrane is not fully understood, which can impede the use of the particles in biomedical applications. Here, a tethered bilayer lipid membrane has been used as a model system to mimic a natural membrane and to study the effect of exposure to small silver nanoparticles with diameters of about 2 nm. The solid supported membrane architecture allowed for the application of surface analytical techniques such as electrochemical impedance spectroscopy and atomic force microscopy. Exposure of the membrane to solutions of the silver nanoparticles led to a small but completely reversible perturbation of the lipid bilayer.

A gene signature identified using a mouse model of androgen receptor-dependent prostate cancer predicts biochemical relapse in human disease.

Mutations in the androgen receptor (AR) have been detected in experimental and clinical prostate tumors. Mice with enforced prostate-specific expression of one such receptor variant, AR-E231G, invariably develop prostatic intraepithelial neoplasia by 12 weeks and metastatic prostate cancer by 52 weeks. The aim of this study was to identify genes with altered expression in the prostates of AR-E231G mice at an early stage of disease that may act as drivers of AR-mediated tumorigenesis. The gene expression profile of AR-E231G prostate tissue from 12-week-old mice was compared to an equivalent profile from mice expressing the AR-T857A receptor variant (analogous to the AR-T877A variant in LNCaP cells), which do not develop prostate tumors. One hundred and thirty-two genes were differentially expressed in AR-E231G prostates. Classification of these genes revealed enrichment for cellular pathways known to be involved in prostate cancer, including cell cycle and lipid metabolism. Suppression of two genes upregulated in the AR-E231G model, ADM and CITED1, increased cell death and reduced proliferation of human prostate cancer cells. Many genes differentially expressed in AR-E231G prostates are also deregulated in human tumors. Three of these genes, ID4, NR2F1 and PTGDS, which were expressed at consistently lower levels in clinical prostate cancer compared to nonmalignant tissues, formed a signature that predicted biochemical relapse (hazard ratio 2.2, p = 0.038). We believe that our findings support the value of this novel mouse model of prostate cancer to identify candidate therapeutic targets and/or biomarkers of human disease.

Corepressor effect on androgen receptor activity varies with the length of the CAG encoded polyglutamine repeat and is dependent on receptor/corepressor ratio in prostate cancer cells.

The response of prostate cells to androgens reflects a combination of androgen receptor (AR) transactivation and transrepression, but how these two processes differ mechanistically and influence prostate cancer risk and disease outcome remain elusive. Given recent interest in targeting AR transrepressive processes, a better understanding of AR/corepressor interaction and responses is warranted. Here, we used transactivation and interaction assays with wild-type and mutant ARs, and deletion AR fragments, to dissect the relationship between AR and the corepressor, silencing mediator for retinoic acid and thyroid hormone receptors (SMRT). We additionally tested how these processes are influenced by AR agonist and antagonist ligands, as well as by variation in the polyglutamine tract in the AR amino terminal domain (NTD), which is encoded by a polymorphic CAG repeat in the gene. SMRT was recruited to the AR ligand binding domain by agonist ligand, and as determined by the effect of strategic mutations in activation function 2 (AF-2), requires a precise conformation of that domain. A distinct region of SMRT also mediated interaction with the AR-NTD via the transactivation unit 5 (TAU5; residues 315-538) region. The degree to which SMRT was able to repress AR increased from 17% to 56% as the AR polyglutamine repeat length was increased from 9 to 42 residues, but critically this effect could be abolished by increasing the SMRT:AR molar ratio. These data suggest that the extent to which the CAG encoded polyglutamine repeat influences AR activity represents a balance between corepressor and coactivator occupancy of the same ligand-dependent and independent AR interaction surfaces. Changes in the homeostatic relationship of AR to these molecules, including SMRT, may explain the variable penetrance of the CAG repeat and the loss of AR signaling flexibility in prostate cancer progression.

Relaxin drives Wnt signaling through upregulation of PCDHY in prostate cancer.

BACKGROUND: Relaxin, a potent peptide hormone of the insulin-like family normally produced and secreted by the human prostate, is upregulated in castrate resistant prostate cancer progression. In various tissues, relaxin increases angiogenesis and cell motility through upregulation of vascular endothelial growth factor, matrix metalloproteases, and nitric oxide, and therefore maybe an attractive target for cancer therapeutics. METHODS: To examine the role of relaxin in prostate cancer progression, LNCaP cells stably transfected with relaxin (LNCaP(RLN)) were used to form xenograft tumors, and microarray expression analysis was subsequently performed to determine novel pathways regulated by relaxin. Prostate cancer tissue microarrays from patient samples were stained by immunohistochemistry for further validation and correlation of the findings. RESULTS: Expression analysis identified novel relaxin regulated pathways, including the ProtocadherinY (PCDHY)/Wnt pathway. PCDHY, which upregulates Wnt11, has previously been shown to stabilize beta-catenin, causing beta-catenin to translocate from the cytoplasmic membrane to the nucleus and initiate TCF-mediated signaling. LNCaP(RLN) xenografts exhibit increased PCDHY expression and increased cytoplasmic localization of beta-catenin, suggesting relaxin directs Wnt11 overexpression through PCDHY upregulation. Similarly, prostate cancer samples from patients who have undergone androgen ablation have increased Wnt11 expression, which is further upregulated in castrate resistant tissues. Like relaxin, Wnt11, and PCDHY are negatively regulated by androgens, and further analysis indicated that the overexpression of relaxin results in dysregulation of androgen-regulated genes. CONCLUSIONS: These data suggest that prostate cancer cell motility and altered androgen receptor activity attributed to relaxin may be mediated in part by Wnt11.

Relaxin becomes upregulated during prostate cancer progression to androgen independence and is negatively regulated by androgens.

BACKGROUND: Relaxin is a potent peptide hormone normally secreted by the prostate. This study characterized relaxin expression during prostate cancer progression to androgen independence (AI), and in response to androgens. METHODS: The prostate cancer cell line, LNCaP, was assayed by microarrays and confirmatory Northern analysis to assess changes in relaxin levels due to androgen treatment and in LNCaP xenografts following castration. Relaxin protein levels were examined by immunohistochemistry (IHC) in tissue microarrays of human prostate cancer samples following androgen ablation. RESULTS: Relaxin levels decreased in a time and concentration-dependent manner due to androgens in vitro, and increased in xenografts post-castration. Relaxin increased in radical prostatectomy specimens after 6 months of androgen ablation and in AI tumors, was highest in bone metastases. CONCLUSIONS: Relaxin is negatively regulated by androgens in vitro and in vivo, which correlates to clinical prostate cancer specimens following androgen ablation. The role of relaxin in angiogenesis and tissue remodeling suggests it may contribute to prostate cancer progression.