Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We generated mice with doxycycline control of a human neurofilament light (NF-L) transgene in the context of the absence (tTA;hNF-L;NF-L(-/-)) or presence (tTA;hNF-L;NF-L(+/-)) of endogenous mouse NF-L proteins. Doxycycline treatment caused the rapid disappearance of human NF-L (hNF-L) mRNA in tTA;hNF-L mice, but the hNF-L proteins remained with a half-life of 3 weeks in the brain. In the sciatic nerve, the disappearance of hNF-L proteins after doxycycline treatment occurred in synchrony along the sciatic nerve, suggesting a proteolysis of NF proteins along the entire axon. The presence of permanent NF network in tTA;hNF-L;NF-L(+/-) mice further stabilized and extended longevity of hNF-L proteins by several months. Surprisingly, after cessation of doxycycline treatment, there was no evidence of leading front of newly synthesized hNF-L proteins migrating into sciatic nerve axons devoid of NF structures. The hNF-L proteins detected at weekly intervals reappeared and accumulated in synchrony at similar rate along nerve segments, a phenomenon consistent with a fast hNF-L transport into axons. We estimated the hNF-L transport rate to be of approximately 10 mm/d in axons devoid of NF structures based on the use of an adenovirus encoding tet-responsive transcriptional activator to transactivate the hNF-L transgene in hypoglossal motor neurons. These results provide in vivo evidence that the stationary NF network in axons is a key determinant of half-life and transport rate of NF proteins.
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PMID:Conditional NF-L transgene expression in mice for in vivo analysis of turnover and transport rate of neurofilaments. 1747 3

Doxycycline (DOX) is widely used as a pharmacological agent and as an effector molecule in inducible gene expression systems. For most applications, it is important to determine whether the DOX concentration reaches the level required for optimal efficacy. We developed a sensitive bioassay for measuring the DOX concentration in biological samples. We used a modified HeLa cell line with the luciferase reporter gene under the control of the DOX-inducible Tet-On system for regulation of gene expression. These HeLaDOX cells constitutively express a novel variant of the rtTA transcriptional activator protein that is highly DOX-sensitive. Incubation of the cells with a DOX-containing biological sample triggers luciferase expression, which can be quantitated by standard methods. This bioassay is sensitive, with a DOX detection limit of 22 ng/ml in plasma. The assay was used to determine the DOX concentration in plasma derived from DOX-treated rhesus macaques and mice. Furthermore, we found that the DOX concentration in murine cerebrospinal fluid is 31-fold lower than the concurrent plasma DOX level. This bioassay for the quantification of DOX concentration in biological samples has several advantages over high-performance liquid chromatography-based and microbiological assays: (1) multiple samples can be assayed in a single experiment; (2) only small sample volumes are required; (3) the assay has a low detection limit; and (4) the assay can be performed in any cell culture laboratory.
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PMID:A sensitive cell-based assay to measure the doxycycline concentration in biological samples. 1920 10

It is well known that NS3/4A protein plays crucial roles in the hepatitis C virus (HCV) replication. NS3/4A protein also results to virus-mediated immune evasion and persistence of infection through the interaction with host proteins. However, the lack of a suitable animal model hampers studies of HCV NS3/4A protein interaction with host proteins, which impacts immunopathology due to infection. Here, transgenic vector containing transcriptional regulation and Fluc reporter gene was constructed to conditionally express NS3/4A protein under the dual control of Tet-On regulatory system and Cre/LoxP gene-knockout system. NS3/4A transgenic founder mice were continuously crossed with Lap transgenic mice expressing reverse tetracycline-controlled transcriptional activator (rtTA), the NS3/4A/Lap double transgenic mouse lines with liver-specifically and conditionally expressing reporter (luciferase Fluc) under control of Tet-On system were established. The NS3/4A/Lap double transgenic mouse are mated with Lap/LC-1 double transgenic mouse with liver-specifically and conditionally expressing Cre recombinase under control of Tet-On system, NS3/4A/Lap/LC-1 triple transgenic mouse were generated. In vivo bioluminescent imaging, western blotting and immunohistochemical staining (IHS) was used to confirm that NS3/4A protein was strictly expressed in the liver of Doxycycline-induced triple transgenic mice. The results show that we established a triple-transgenic mouse model conditionally expressing the HCV NS3/4A protein under strict control of the Tet-On regulatory system and Cre/loxP system. This novel transgenic mouse model expressing NS3/4A in a temporally and spatially-specific manner will be useful for studying interactions between HCV NS3/4A protein and the host, also for evaluating NS3/4A protease inhibitors.
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PMID:Establishment of a novel triple-transgenic mouse: conditionally and liver-specifically expressing hepatitis C virus NS3/4A protease. 2520 Apr 33

The retinoblastoma family of pocket proteins (pRBs), composed of Rb1, p107, and p130 are negative regulators of cell-cycle progression. The deletion of any individual pRB in the auditory system triggers hair cells' (HCs) and supporting cells' (SCs) proliferation to different extents. Nevertheless, accessing their combined role in the inner ear through conditional or complete knockout methods is limited by the early mortality of the triple knockout. In quiescent cells, hyperphosphorylation and inactivation of the pRBs are maintained through the activity of the Cyclin-D1-cdk4/6 complex. Cyclin D1 (CycD1) is expressed in the embryonic and neonatal inner ear. In the mature organ of Corti (OC), CycD1 expression is significantly downregulated, paralleling the OC mitotic quiescence. Earlier studies showed that CycD1 overexpression leads to cell-cycle reactivation in cultures of inner ear explants. Here, we characterize a Cre-activated, Doxycycline (Dox)-controlled, conditional CycD1 overexpression model, which when bred to a tetracycline-controlled transcriptional activator and the Atoh1-cre mouse lines, allow for transient CycD1 overexpression and pRBs' downregulation in the inner ear in a reversible fashion. Analyses of postnatal mice's inner ears at various time points revealed the presence of supernumerary cells throughout the length of the cochlea and in the vestibular end-organs. Notably, most supernumerary cells were observed in the inner hair cells' (IHCs) region, expressed myosin VIIa (M7a), and showed no signs of apoptosis at any of the time points analyzed. Auditory and vestibular phenotypes were similar between the different genotypes and treatment groups. The fact that no significant differences were observed in auditory and vestibular function supports the notion that the supernumerary cells detected in the adult mice cochlea and macular end-organs may not impair auditory functions.
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PMID:Spatiotemporally controlled overexpression of cyclin D1 triggers generation of supernumerary cells in the postnatal mouse inner ear. 3224 47