The regulatory role of the transcription factor Crz1 in stress tolerance, pathogenicity, and its target gene expression in Metarhizium acridum

Abstract Cyclin-dependent kinase-6 (CDK6) is required for early thymocyte development and tumorigenesis. To mechanistically dissect the role of CDK6 in thymocyte development, we generated and analyzed mutant knock-in mice and found that mice expressing a kinase-dead Cdk6 allele (Cdk6K43M) had a pronounced reduction in thymocytes and hematopoietic stem cells and progenitor cells (Lin−Sca-1+c-Kit+ [LSK]). In contrast, mice expressing the INK4-insensitive, hyperactive Cdk6R31C allele displayed excess proliferation in LSK and thymocytes. However, this is countered at least in part by increased apoptosis, which may limit progenitor and thymocyte expansion in the absence of other genetic events. Our mechanistic studies demonstrate that CDK6 kinase activity contributes to Notch signaling because inactive CDK6 kinase disrupts Notch-dependent survival, proliferation, and differentiation of LSK, with concomitant alteration of Notch target gene expression, such as massive up-regulation of CD25. Further, knockout of CD25 in Cdk6K43M mice rescued most defects observed in young mice. These results illustrate an important role for CDK6 kinase activity in thymocyte development that operates partially through modulating Notch target gene expression. This role of CDK6 as a downstream mediator of Notch identifies CDK6 kinase activity as a potential therapeutic target in human lymphoid malignancies.

Download Full-text

Hepatocyte Nuclear Factor 4 alpha (HNF4α) Activation is Essential for Termination of Liver Regeneration

10.1101/304808 ◽

2018 ◽

Author(s):

Ian Huck ◽

Sumedha Gunewardena ◽

Regina Espanol-Suner ◽

Holger Willenbring ◽

Udayan Apte

Keyword(s):

Gene Expression ◽

Liver Regeneration ◽

Target Gene ◽

Nuclear Factor ◽

Hepatocyte Nuclear Factor ◽

Hepatic Differentiation ◽

Target Gene Expression ◽

Protein Levels ◽

Hepatocyte Nuclear Factor 4

AbstractHepatocyte Nuclear Factor 4 alpha (HNF4α) is critical for hepatic differentiation. Recent studies have highlighted its role in inhibition of hepatocyte proliferation and tumor suppression. However, the role of HNF4α in liver regeneration is not known. We hypothesized that hepatocytes modulate HNF4α activity when navigating between differentiated and proliferative states during liver regeneration. Western blot analysis revealed a rapid decline in nuclear and cytoplasmic HNF4α protein levels accompanied with decreased target gene expression within 1 hour after 2/3 partial hepatectomy (post-PH) in C57BL/6J mice. HNF4α protein expression did not recover to the pre-PH levels until day 3. Hepatocyte-specific deletion of HNF4α (HNF4α-KO) in mice resulted in 100% mortality post-PH despite increased proliferative marker expression throughout regeneration. Sustained loss of HNF4α target gene expression throughout regeneration indicated HNF4α-KO mice were unable to compensate for loss of HNF4α transcriptional activity. Deletion of HNF4α resulted in sustained proliferation accompanied by c-myc and cyclin D1 over expression and a complete deficiency of hepatocyte function after PH. Interestingly, overexpression of degradation-resistant HNF4α in hepatocytes did not prevent initiation of regeneration after PH. Finally, AAV8-mediated reexpression of HNF4α in hepatocytes of HNF4α-KO mice post-PH restored HNF4α protein levels, induced target gene expression and improved survival of HNF4α-KO mice post-PH. In conclusion, these data indicate that HNF4α reexpression following initial decrease is critical for hepatocytes to exit from cell cycle and resume function during the termination phase of liver regeneration. These results reveal the role of HNF4α in liver regeneration and have implications for therapy of liver failure.

Download Full-text

Abstract 13: Development of Functionalized Nanoparticle Platform for Reducing Atherosclerosis

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.35.suppl_1.13 ◽

2015 ◽

Vol 35 (suppl_1) ◽

Author(s):

Shobha Ghosh ◽

Jing Wang ◽

Jinghua Bie ◽

Quan Yuan ◽

Olga Zolotarskaya ◽

...

Keyword(s):

Gene Expression ◽

Animal Studies ◽

Target Gene ◽

Foam Cells ◽

Expression Vectors ◽

Transgenic Expression ◽

Target Gene Expression ◽

Macrophage Foam Cells ◽

Plaque Regression

No therapy is currently available to enhance the removal of cholesteryl esters (CE) from existing atherosclerotic plaques to facilitate plaque regression. Such a strategy is crucial to reduce the burden of existing disease in addition to preventing the progression targeted by the current therapeutics. Earlier studies from our laboratory have established the anti-atherogenic role of CE hydrolase (CEH)-mediated CE mobilization from macrophage foam cells and final elimination of cholesterol by the liver. While transgenic expression of CEH was used in pre-clinical animal studies, increase in human CEH by activation of Liver-X-receptor (LXR) was also established. Increased lipogenesis induced by LXR ligands precludes their use. The current studies focused on the development of mannose-functionalized dendrimer nanoparticles (DNPs) for the delivery of LXR ligand (TO901317) or CEH expression vector to plaque associated macrophage foam cells. As shown in the Figure, mannose functionalization restricts the uptake of DNPs to macrophages and minimal uptake was seen with primary hepatocytes ( A ). Western diet fed LDLR-/- mice were injected (iv) with DNPs and tissues harvested 48 later to monitor gene expression by QPCR. DNP-mediated delivery of LXR ligand (DNP-LXR) increased the target gene expression (ABCA1, ABCG1) in plaque associated macrophage foam cells in the aortic arch with no effects on target gene expression in the liver ( B ) demonstrating the specific delivery of LXR ligand. Comparable increase in CEH activity was seen following exposure of macrophages to free LXR ligand and DNP-delivered LXR ligand ( C ) and DNP-mediated delivery of CEH expression vectors driven either by CMV or SR-A promoter induced dramatic increase in CEH expression ( D ). These data establish functionalized DNP as a suitable platform for specific and functional delivery of drugs or DNA to plaque associated macrophages to enhance processes involved in cholesterol removal and plaque regression.

Download Full-text

Sumoylation of bZIP Transcription Factor NRL Modulates Target Gene Expression during Photoreceptor Differentiation

Journal of Biological Chemistry ◽

10.1074/jbc.m110.142810 ◽

2010 ◽

Vol 285 (33) ◽

pp. 25637-25644 ◽

Cited By ~ 25

Author(s):

Jerome E. Roger ◽

Jacob Nellissery ◽

Douglas S. Kim ◽

Anand Swaroop

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Target Gene ◽

Bzip Transcription Factor ◽

Target Gene Expression

Download Full-text

MiR-124 synergism with ELAVL3 enhances target gene expression to promote neuronal maturity

10.1101/2020.03.25.006635 ◽

2020 ◽

Author(s):

Ya-Lin Lu ◽

Yangjian Liu ◽

Matthew J. McCoy ◽

Andrew S. Yoo

Keyword(s):

Gene Expression ◽

Mirna Target ◽

Target Gene ◽

Target Genes ◽

Dependent Manner ◽

Neuronal Function ◽

Mirna Target Gene ◽

Target Gene Expression ◽

Human Neurons

SummaryNeuron-enriched microRNAs (miRNAs), miR-9/9* and miR-124 (miR-9/9*-124), direct cell fate switching of human fibroblasts to neurons when ectopically expressed by repressing anti-neurogenic genes. How these miRNAs function after the onset of the transcriptome switch to a neuronal fate remains unclear. Here, we identified direct targets of miRNAs by Argonaute (AGO) HITS-CLIP as reprogramming cells activate the neuronal program and reveal the role of miR-124 that directly promotes the expression of its target genes associated with neuronal development and function. The mode of miR-124 as a positive regulator is determined by a neuron-enriched RNA-binding protein, ELAVL3, that interacts with AGO and binds target transcripts, whereas the non-neuronal ELAVL1 counterpart fails to elevate the miRNA-target gene expression. Although existing literature indicate that miRNA-ELAVL1 interaction can result in either target gene upregulation or downregulation in a context-dependent manner, we specifically identified neuronal ELAVL3 as the driver for miRNA target gene upregulation in neurons. In primary human neurons, repressing miR-124 and ELAVL3 led to the downregulation of genes involved in neuronal function and process outgrowth, and cellular phenotypes of reduced inward currents and neurite outgrowth. Results from our study support the role of miR-124 promoting neuronal function through positive regulation of its target genes.

Download Full-text

Role of the Distal sarA Promoters in SarA Expression in Staphylococcus aureus

Infection and Immunity ◽

10.1128/iai.73.7.4391-4394.2005 ◽

2005 ◽

Vol 73 (7) ◽

pp. 4391-4394 ◽

Cited By ~ 17

Author(s):

Ambrose L. Cheung ◽

Adhar C. Manna

Keyword(s):

Gene Expression ◽

Staphylococcus Aureus ◽

Protein Level ◽

Target Gene ◽

Open Reading Frame ◽

Reading Frame ◽

Regulatory Locus ◽

Target Gene Expression

ABSTRACT The global regulatory locus sarA comprises a 375-bp open reading frame that is driven by three promoters, the proximal P1 and distal P3 and P2 promoters. We mutated the weaker P3 and P2 promoters to ascertain the effect of the change on SarA protein and target gene expression. Our results indicated that the solely active P1 promoter led to a lower SarA protein level, which has an effect on agr transcription and subsequently had corresponding effects on hla, sspA, and spa transcription, probably in both agr-independent and agr-dependent manners.

Download Full-text

Relationship of DUX4 and target gene expression in FSHD myocytes

10.1101/2020.05.24.109710 ◽

2020 ◽

Author(s):

Jonathan Chau ◽

Xiangduo Kong ◽

Nam Nguyen ◽

Katherine Williams ◽

Rabi Tawil ◽

...

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Target Gene ◽

Target Genes ◽

Myoblast Differentiation ◽

Target Gene Expression ◽

Gene Transcripts ◽

Relationship Of

AbstractFacioscapulohumeral dystrophy (FSHD) is linked to misexpression of the transcription factor, DUX4. Although DUX4 target gene expression is often readily detectable, analysis of DUX4 expression has been limited due to its low expression in patient samples. Recently, single cell/nucleus RNA-sequencing was used to detect the native expression of DUX4 for the first time, but important spatial relationships with its target gene expression was missing. Furthermore, dynamics of DUX4 expression during myoblast differentiation has not been fully explored. In order to study the spatiotemporal relationship of DUX4 and key target genes, we performed RNA FISH on immortalized FSHD2 patient skeletal muscle cells. Using two probe sets, DUX4 transcripts were detected in 1-4% of myotubes after 3-day differentiation in vitro. We found that DUX4 transcripts mainly localize as foci in one or two nuclei in a myotube compared to abundant accumulation of the target gene transcripts in the cytoplasm. Over a 13-day differentiation timecourse, DUX4 expression without target gene expression significantly increased and peaked at day 7. Target gene expression correlates better with DUX4 expression early in differentiation while the expression of target genes without detectable DUX4 transcripts increases later. Consistently, shRNA depletion of DUX4-activated transcription factors, DUXA and LEUTX, specifically repressed a DUX4-target gene, KDM4E, later in differentiation, suggesting that following the initial activation by DUX4, target genes themselves contribute to the maintenance of downstream gene expression. Together, in situ detection of the DUX4 and target gene transcripts provided new insight into dynamics of DUX4 transcriptional network in FSHD patient myocytes.Significance StatementFSHD is the third most common muscular dystrophy and is associated with upregulation of DUX4, a transcription factor, and its target genes. Although target genes are easily detectable in FSHD, low frequency DUX4 upregulation in patient myocytes is difficult to detect, and examining the relationship and dynamics of DUX4 and target gene expression without artificial overexpression of DUX4 has been challenging. Using RNAScope with highly specific probes, we detect the endogenous DUX4 and target gene transcripts in situ in patient skeletal myotubes during differentiation in vitro. Our study reveals a unique DUX4 expression pattern and its relationship to the expression of target genes, and evidence for self-sustainability of the target gene network. The study provides important new insights into the FSHD disease mechanism.

Download Full-text