Information

Are androgenic-anabolic steroids a form of gene editing?


Is taking AAS a form of gene-editing? Steroids alter genes in some way since they allow people to build more muscle than what's naturally possible -- so they sort of "break" natural genetics somehow.

Given this, would this be considered a form of genetic-engineering on living humans/etc.? What about relative things like myostatin-inhibiting to prevent muscle growth cell limitation or HGH use?

In summary: does the use of AAS/performance enhancing drugs/etc. constitute gene editing? If not, why -- and if so, why and how is it comparable to things like CRISPR and stem-cell/etc. methods?


Steroids are not a form of gene editing

A gene is a sequence of DNA. Gene editing means changing this DNA sequence, kind of like changing the letters in a book.

Essentially all drugs, steroids included, affect the body without changing DNA sequence. Often they bind to a protein, which is the product of a gene, and alter its function. Steroids bind and alter the activity of transcriptiton factors, which are kind of like switches that turn certain genes on and off.

If gene editing is like rewriting a book, taking a drug would be like changing how, when, or where someone reads from the book, without altering the text itself.

If you are interested in how all of this works, you can check out some great free online courses like this: https://www.khanacademy.org/science/biology#intro-to-biology


2. Steroid Hormones

Steroid hormones include the sex hormones, glucocorticoids, and mineralocorticoids. Within the family of sex hormones are the androgens, estrogens, and progestogens. All of the steroid hormones bind to their own specific receptor, which may be cytosolic or nuclear, to induce changes within a cell. All natural steroid hormones are synthesized from cholesterol in the adrenal glands and/or gonads. Some steroid hormones are further metabolized in the liver, peripheral and/or target tissues. As their precursor is cholesterol, they are hydrophobic in nature which allows them to pass easily through cell membranes. Once synthesized, the steroid hormones are carried in the blood stream bound to carrier proteins such as albumin, steroid hormone-binding globulin (SHBG) or corticosteroid-binding globulin to target tissues.

The androgen produced in the highest concentration in the body is testosterone (T). This is a 19-C steroid that has androgenic and anabolic effects within the body. T is primarily produced in the gonads but a small amount is produced in the adrenal cortex or from the peripheral conversion of androstenedione. T production is much greater in males than in females (5,000–7,000 μmg/day versus 300 μmg/day) [2]. In males, T is primarily produced by the Leydig cells in the testes whereas in females, the primary production of T occurs in the Theca cells of the ovaries. In both sexes, small amounts come from the adrenal cortex and the peripheral conversion of androstenedione.

T acts in the body by acting directly through the AR or indirectly via metabolism to other sex steroids. T can be aromatized to estradiol (E2) which activates ER-α and/or ER-β. Alternatively, T can be irreversibly converted to the more potent 5α-dihydrostestosterone (5α-DHT) by the enzyme 5α-reductase. T has many physiological actions in the body. It acts on muscles to stimulate growth and maintenance, it promotes bone development while inhibiting bone resorption, it increases red blood cell and hemoglobin levels, augments libido and erectile function, enhances mood and cognition, and induces lipolysis. Low testosterone levels or deficit in androgen action induces frailty, sarcopenia, poor muscle quality, muscle weakness, hypertrophy of adipose tissue and impaired neurotransmission.


Methods

This systematic review was prepared according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guideline [9]. A literature search was performed in 7 relevant databases, including Scopus, Medline, Embase, ISI Web of Knowledge, Cochrane central register of controlled trials, Cochrane database systematic reviews, and Google Scholar. To confirm consistency and accuracy of results, searches were performed by two authors independently (DDD & IK). At 3 stages, titles, abstracts, and full text of studies were evaluated. At the final stage, required data was extracted from the selected articles. The following keywords were used as search terms: “anabolic steroids”, “androgenic steroids”, “anabolic-androgenic steroids”, “androgens”, “anabolics”, “growth hormone”, “recombinant human growth hormone”, “somatropin”, “acute kidney injury”, “chronic kidney disease”, “renal dysfunction”, “renal impairment”, “renal damage”, and “renal insufficiency”. Randomized clinical trials, prospective or retrospective human studies, case series as well as case reports, and experimental (in vivo) studies were included in this review. The reference lists of published articles were also examined for identifying any additional relevant studies. Regarding publication date, articles published from 1950 to December 2017 were considered in this review. Non-English language articles, congress abstracts, newspaper articles, and in vitro studies were not eligible for inclusion. The studies included in the systematic review were reviewed by all the authors to ensure that they met the inclusion criteria. Any possible discrepancies were discussed by the authors. By taking into account the above inclusion and exclusion criteria, 21 published articles were considered in our review. These articles included experimental studies (n = 8), case report or case series (n = 8), pilot clinical trial (n = 3), placebo-controlled, cross-over clinical trial (n = 1), and randomized, cross-over clinical trial (n = 1). Quality of clinical studies was evaluated using the Jadad score. This score for the studies concerning growth hormone (n = 5) ranged from − 1 to + 2. Figure 1 depicts the flow diagram of our study selection process. 1327 and 3341 studies relevant to anabolic-androgenic steroids and growth hormone respectively, were excluded from this systematic review. This exclusion was mainly due to duplication in different databases.

Flow diagram of study selection for anabolic-androgenic steroids (a) and growth hormone (b)


Results

Characteristics of Participants

A total of 37 current AAS abusers, 33 former AAS abusers and 31 control participants volunteered to participate in the study. One participant from the control group was excluded due to cryptorchidism which was diagnosed during the study, so 30 control participants were included in the final analyses. The participants in the three groups did not differ significantly with respect to age, smoking history, illicit drug abuse history, income or marital status, but current AAS abusers performed strength training more hours per week than participants in the other two groups (P < 0.05) (Table 1).

A higher proportion of participants in the control group had a university degree than the participants in the other two groups (P < 0.01). The total duration of accumulated AAS abuse (geometric mean (95%CI)) noted among current AAS abusers (142.3 (99.7 203.1) weeks) was not significantly different from that noted among former AAS abusers (111.8 (81.3 153.7) weeks), and the numbers of AAS compounds used did also not differ between the two groups. The two groups reported previous and current experience with varying doses of numerous AAS compounds, of which testosterone esters, trenbolone, nandrolone, stanozolol, sustanon and boldenone were the most widely used (S1 Table). High proportions of both current and former AAS abusers reported regularly using hCG or aromatase inhibitors following AAS cycles. The elapsed duration since AAS cessation (geometric mean (95%CI)) was 2.5 (1.7 3.7) years among former AAS abusers. None of these participants reported having used AAS within six months and only 15.2% (95%CI) (3.0 27.4) reported elapsed time interval of 6–12 months since AAS cessation. Eleven former AAS abusers had previously been referred to an endocrine clinic for gynaecomastia, but none had been treated for gynaecomastia, hypogonadism or infertility. These participants did not differ from other former AAS abusers in terms of demographic characteristics, AAS abuse, laboratory results or frequency of hypogonadal symptoms.

Reproductive Hormones

Testicular size differed significantly among the three groups. Current AAS abusers had the smallest testicular volume (12.2 (0.7) ml) and former AAS abusers had a volume of 17.4 (0.8) ml which was 4.8 (2.9 6.8) ml smaller than that of the control participants who had largest testicular volume (Table 2). Plasma total and free testosterone levels were significantly lower among former AAS abusers than among control participants and current AAS abusers, the latter of whom exhibited significantly increased plasma testosterone levels, as expected. The 2.5 th – 97.5 th percentiles for total testosterone ranged from 12.4–32.3 nmol/l among the control participants and 5.7–31.4 nmol/l among former AAS abusers.

A high percentage of participants in the group of former AAS abusers (27.2% (13.3 45.5)) were below the lower reference limit for plasma total testosterone estimated in nonobese eugonadal healthy young men (12.1 nmol/l) whereas no participants in the control group (0.0% (0.0 11.6)) were below this limit (P < 0.01). Further, among former AAS abusers 3.3% (0.01 15.8) were below the lower reference limit for plasma total testosterone estimated in a pooled population-representative cohort (6.6 nmol/l). Plasma gonadotropins, SHBG, 17-hydroxyprogesterone, serum AMH and inhibin B did not differ significantly between former AAS abusers and control participants, but were markedly decreased among current AAS abusers (P < 0.01). There were higher percentages of participants with serum inhibin B levels below the limit of impaired spermatogenesis (92 pg/ml) among current AAS abusers (56.8% (39.5 72.7)) and former AAS abusers (9.1% (1.9 24.3)) than among control participants (3.3% (0.01 17.2)) (trend analysis: P < 0.01).

Accumulated duration of AAS abuse was associated with reduced testicular size in former abusers (log2 coefficient (B) (95%CI): -1.3 (-2.4 -0.2), P = 0.02) and current AAS abusers (during the initial 32 weeks of AAS abuse, spline function, log2 coefficient (B): -5.4 (-10.8 -0.02), P = 0.049) (Fig 1). We did not observe any significant associations between plasma total testosterone levels and accumulated duration of AAS abuse (log2 coefficient (B): 0.09 (-0.04 0.22), P = 0.17) (Fig 2) or elapsed duration since AAS cessation (log2 coefficient (B): 0.05 (-0.7 0.17), P = 0.42) (Fig 3) among former AAS abusers.

Footnote: AAS, anabolic androgenic steroids.

Footnote: AAS, anabolic androgenic steroids.

Footnote: AAS, anabolic androgenic steroids.

Among current AAS abusers, increasing accumulated duration of AAS abuse was associated with decreasing serum inhibin B levels, which reached a plateau after 64 weeks of accumulated AAS abuse (spline function, log2 coefficient (B): -47.9 (-80.3 -15.6), P < 0.01) (Fig 4). Increasing accumulated duration of AAS abuse was also associated with decreasing AMH levels among current AAS abusers (log2 coefficient (B): -0.3 (-0.5 -0.04), P = 0.03) (Fig 5).

Footnote: AAS, anabolic androgenic steroids s-, serum.

Footnote: AAS, anabolic androgenic steroids.

Symptoms Indicating Hypogonadism

Former AAS abusers exhibited the highest frequencies of participants with depressive symptoms (24.2% (11.1 42.2)), erectile dysfunction (27.3% (13.3 45.6)) and decreased libido (40.1% (23.2 57.0)) compared with the other two groups (trend analyses: P < 0.05 for all three parameters) (Fig 6, S2 Table). Former AAS abusers had a lower score on the SF-36 questionnaire with respect to ‘energy/fatigue’ (58.9 (4.3)) than the control group (73.5 (2.6)) and current AAS abusers (69.2 (4.5)) indicating former AAS abusers exhibited significantly more pronounced fatigue symptoms than their counterparts (P < 0.05). We did not observe any significant associations between symptoms and hormonal levels or extent of AAS abuse among former AAS abusers.

Footnote: T bars show standard errors. Depressive symptoms, erectile dysfunction and decreased libido were compared across the groups with trend analyses and all were statistically significant (P < 0.05). AAS, anabolic androgenic steroids.


How does the treatment work?

Hunter syndrome results from a mutation in a gene for an enzyme that cells need to break down certain sugars. When the enzyme is defective or missing, the sugars build up and can cause developmental delays, organ problems, brain damage, and early death. Brian Madeux, the first patient in what will be a small clinical trial has a mild form of the disease, but nevertheless has had more than two dozen operations as a result, AP reports.

Someday, researchers may be able to use gene editing to repair the flawed gene in cells that causes diseases like Hunter syndrome. However, that’s not the goal of the trial, sponsored by Sangamo Therapeutics, a biotech company based in Richmond, California. Instead, the company inserts a replacement copy of the gene, using gene editing to snip the DNA helix of liver cells in a specific place near the promotor, or on-off switch, for the gene for a protein called albumin. The cells fix the damage by inserting the DNA for the new gene, supplied by the researchers along with the gene editor’s DNA scissors, and the gene’s activity is then controlled by the powerful albumin promotor. The idea is to turn these modified liver cells into a factory for making the enzyme missing in Hunter syndrome.

Sangamo’s targeted approach, known as “safe harbor,” should avoid the risks of using traditional gene therapy to alter a cell's genome, which pastes in the new gene at a random place in the genome and can potentially turn on a cancer gene. And because the body doesn’t need much of the enzyme, modifying just a small fraction of the liver’s cells should be enough to treat the disease.

Although Hunter syndrome patients often receive weekly infusions of the missing enzyme, their blood levels drop within a day, says Sangamo CEO Sandy Macrae. The hope is that the one-time gene-editing treatment—given as a 3-hour intravenous infusion—will allow the liver to keep making the enzyme at a steady rate for years. There is a caveat, however: The enzyme Hunter patients now receive does not cross the blood-brain barrier, the tight network of cells that protects the brain from pathogens, and the livermade enzyme produced by the gene edit may not either. So the new treatment may not stop the brain damage that can occur in Hunter syndrome.


Background

Androgen receptor (AR)-mediated transcription is the primary driver of prostate cancer (PCa) growth and proliferation [1]. Activation of this critical signaling pathway occurs when AR binds to androgens such as testosterone or dihydrotestosterone (DHT). This induces the translocation of the AR into the nucleus, where it interacts with DNA at AR binding sites (ARBS). Almost all of these cis-regulatory elements (CREs) are located at distal intergenic or intronic regions [2, 3]. The AR cistrome is influenced by various transcription factors and pioneer factors, including FOXA1, HOXB13, and GATA2 [2, 4, 5]. Once bound to DNA, the AR recruit numerous co-activators (CBP/p300, SRC/p160), chromatin modifiers (SWI/SNF-BRG1), and co-repressors (HDAC, NCoR) in a highly coordinated manner [6]. This protein complex physically interacts with gene promoters via chromosomal loops, activating basal transcriptional machinery to drive transcription. Yet similar to other nuclear receptors, most AR-regulated genes interact with multiple ARBS [7]. There are vastly more ARBS (tens of thousands) than AR-regulated genes (hundreds) [8, 9]. We do not know if these ARBS enhancers interact in an additive, synergistic, or dominant mechanism to induce gene transcription. Characterization of ARBS enhancer activity is critical to interpret the underlying regulatory logic of this transcription factor.

Enhancers have traditionally been identified by correlating transcription factor binding sites with chromatin accessibility, RNA polymerase II, GROseq, or enhancer-associated histone modifications such as H3K27ac [10,11,12,13]. These features all broadly correlate with active enhancers, but they are not causative and therefore are extremely prone to false positives [14]. For example, global loss of the enhancer mark H3K27ac has no functional impact on gene transcription, chromatin accessibility, or histone modifications [15]. Therefore, ectopic reporter assays, which quantify the enhancer-induced transcription of a gene, still remain the cornerstone of enhancer validation [16]. These assays are not influenced by endogenous chromatin compaction or epigenetic modifications and can test the potential enhancer capability of each specific CRE [17]. While robust, conventional approaches are very low-throughput. To overcome these limitations, several massively parallel reporter assays (MPRA) have been developed including Self-Transcribing Active Regulatory Regions sequencing (STARRseq) [18]. In this method, enhancer activity is quantified by measuring the rate of self-transcription of the genomic region cloned downstream of a minimal promoter. By quantifying self-transcribed mRNA, the enhancer activity of many thousands of potential regulatory sites can be measured simultaneously and provide locus-specific resolution.

There is increasing clinical evidence that non-coding mutations can act as oncogenic drivers in PCa [19,20,21]. Recent studies by our lab and others have shown that ARBS are highly mutated in a tissue-specific manner [22, 23]. Given the critical role of AR in PCa progression and treatment resistance, any changes to the transcriptional landscape could alter tumor cell proliferation and sensitivity to AR pathway inhibitors. However, establishing a causal link between non-coding mutations and PCa growth is extremely challenging due to the lack of functional CRE annotation. Therefore, the vast majority of these non-coding mutations remain unexplored in PCa. Better characterization of these CRE in PCa is essential to stratify potential driver mutations.

To provide the first locus-specific AR regulatory map, we functionally quantified the enhancer activity of all commonly observed clinical ARBS with STARRseq. We demonstrated that only 7% of ARBS have androgen-dependent enhancer activation, while 11% had enhancer activity that was independent of AR binding. Surprisingly, the vast majority of ARBS (81%) did not have significant androgen-dependent or constitutively active enhancer activity. These in vitro annotations strongly correlated with enhancer associated histone modifications in clinical PCa samples. To characterize the mechanism of AR enhancers, we then trained a machine learning classifier that successfully predicted active enhancers and identified key features of active enhancers. Integrating both the long-range chromatin interactome and transcriptomic data, we found that androgen inducible enhancers were significantly more enriched as anchors for gene looping and acted as “hubs” to activate AR-regulated genes. Finally, combining these results with whole genome sequencing of primary and metastatic PCa, we identified and characterized a non-coding somatic mutation that significantly impacted AR enhancer activity of a critical tumor suppressor.


INTRODUCTION

Anabolic-androgenic steroids (AAS) are synthetic substances derived from testosterone (Fig. ​ 1 1 ) that are employed for their trophic effect on muscle tissue, with a net result in increased muscle mass and strength. These effects, in conjunction with the neurostimulatory ones, may explain the large prevalence of AAS among athletes at all levels [1-7]. Athletes, and namely bodybuilders and weightlifters, are the main users of these substances [1, 6]. Individuals who desire a lean appearance and muscular appearance are also implicated in this [2, 3, 7, 8-18].

The three major classes of anabolic androgen steroids (modified from Oberlander, J.G. Henderson, L.P, 2012, cited sub 51).

Although the use of anabolic steroids for cosmetic purposes is incorrectly thought to be relatively harmless, contrarily, anabolic steroids are harmful to health [4, 19-21]. In fact, their consumption can trigger a series of adverse side effects on the body. It is generally believed that side effects of AAS could develop only as a result of long-term use [22]. However, acute adverse effects have also been described, primarily consisting of headaches, fluid retention, gastrointestinal irritation, diarrhoea, abdominal pain, jaundice, menstrual abnormalities, and hypertension. The chronic effects of AAS abuse aside from the neuro-psychiatric and behavioral effects include a wide range of somatic consequences. Many organs and systems are targets of AAS action consequently, AAS may exert negative effects on reproductive, hepatic, musculoskeletal, endocrine, renal, immunologic, cardiovascular, cerebrovascular, and hematological systems [5, 23-27].

Neuropsychiatric and behavioral effects of AAS abuse are well known and described in the literature [9, 12, 28-52]. In rodents, long-term administration of certain AAS induces behavioral and neurochemical changes [44, 53-58], which may resemble similar behavioral modifications observed in AAS abusers.

However, the neurodegenerative effects of long term AAS abuse are part of not yet evident phenomenon in which the negative effects of these drugs remain clinically silent during the young age. Most of the world’s illicit AAS users are still under the age of 50, too early for clear symptomatic manifestations (cognitive or motor deficits) of possible neurotoxic effects. [59]. Recently, Kanayama et al. [59] reported that visio-spatial memory of long-term AAS users was significantly worse than in AAS non-users. Moreover the same Authors reported that visio-spatial performance showed a significant negative correlation with total lifetime AAS dosing [59]. These observations are in line with the experimental data reported by Pierretti et al. [60] who demonstrated that rats administered with supraphysiologic AAS doses showed spatial memory deficits.

There is growing evidence that non-medical use of AAS has a neurodegenerative potential. Although the nature of this effect is still largely not clarified, recent animal studies have shown the recurrence of neurotoxic effects of AAS, ranging from neurotrophin unbalance to increased neuronal susceptibility to apoptotic stimuli [61].

The current paper aims to investigate the neurotoxicity related to AAS abuse and the underlying hypothesized mechanisms.


Editing anemias

The second trial of gene therapy was substantially smaller, and the therapy was far more complex. It focused on two types of anemia where the underlying mutations provide some protection from malaria: sickle-cell anemia and a form of β-thalassemia. These alter the function of red blood cells and cause severe health issues. β-thalassemia damages one of the genes for hemoglobin, resulting in a severe underproduction people with sickle-cell disease produce a hemoglobin that forms polymers, resulting in misshapen red blood cells.

While it's possible to treat β-thalassemia by a gene therapy similar to the one that worked for hemophilia—simply provide a replacement copy of the defective gene—that won't necessarily work for sickle-cell anemia, which produces an altered form of hemoglobin. One of the ideas that has been considered for treating these anemias is to reactivate the fetal hemoglobin gene. This has a higher affinity for oxygen, allowing it to pick up oxygen from the adult form in the placenta. But it shuts off within a few years of birth.

This shutdown is mediated in part by a protein called BCL11A. So, in theory, if you eliminate BCL11A, you can reactivate the fetal hemoglobin genes. Unfortunately, getting rid of it isn't simple, because it performs essential functions in other cells.

To get around this problem, the researchers behind the new work obtained blood stem cells from patients with β-thalassemia and sickle-cell disease. These were then subjected to CRISPR gene editing, which deleted a piece of DNA that was essential for activating BCL11A in red blood cells. It wasn't perfectly efficient, as you'd expect, but it did reach levels where about 80 percent of the copies of BCL11A had the editing performed. And, when these edited stem cells formed red blood cells in culture, they produced elevated levels of fetal hemoglobin.

The actual clinical trial involved a risky procedure: the blood stem cells of two patients, one with β-thalassemia, one with sickle-cell disease, were eliminated. The gene-edited stem cells were then infused, allowing the patients to develop a new blood supply using them. This is a very aggressive procedure and requires extensive medical support both had severe events that required treatment during the recovery. A profile of one of the trial's participants may help explain why someone would risk it.


Lentiviral Vectors Available

The GET iN Core has tested and currently offers a variety of lentiviral expression vectors for protein and shRNA expression and the delivery of transcription factor reporters. These vectors are both commercial and internally acquired from core collaborators and patrons. The DNA/RNA delivery core offers vector maps and sequences and consults on approaches for cloning in the available vectors. Below you will find a short discussion of the vectors available from the GET iN Core.

 Lentiviral vectors for protein expression

  1. pLVX   family of vectors (Clontech) which contain CMV promoter that drivers expression of a cDNA, PGK promoter that controls expression of puromycine resistance gene. These vectors contain GFP to be expressed as protein fusion tag on either C or N terminus.
  2. pCDH   family of expression vectors (System Biosciences) are the Core's most popular protein expression vectors due convenient design of their multiple cloning sites and optimized choice of promoters for control of protein expression (CMV) and expression of the antibiotic resistance gene (EF- 1alpha). CMV and EF1alpah promoters are most similar in the expression potential, although EF- 1alpha is slightly weaker than CMV, that provides high expression levels of both transgene and antibiotic resistance gene.
  3. pLU   lentiviral vector (Wistar Institute) implied by the Core for expression of secreted proteins such as cytokines and growth factors. The vector harbors PGK promoter controlling expression of a protein of interest that is linked with RFP through IRES sequence. The PGK promoter provides robust expression in various human and mouse cell types with expression levels close to physiological.
  4. Protein expression vectors with pre-cloned ORF/cDNA encoding human and mouse proteins, such as   pLV   (Genecopaeia) and   pLOC   (Open Biosystems). Being typical lentiviral expression vectors, these are a good choice to acquire vectors that already contain an ORF/cDNA for protein of interest which is ready to be use for virus generation by the Core.
  5. Vectors for stable and robust cell labeling with fluorescent proteins (GFP, RFP, Tomato) and Luciferase for in vivo experiments on cells injected in to the animals. Vector pFULT vector expresses Luciferase linked to Tamato under the control of the human PGK1 promoter. Vector pGreenFire expresses GFP and Luciferase separated by a T2A link under control of the CMV promoter.

The core also carries lentiviral expression vectors that express different antibiotic resistance genes such as neomycine, blactocidine and puromycine. Therefore, if available, the core can offer generation of cell lines and primary cells stably infected with two and three proteins.

 Lentiviral vectors for expression of shRNA/miR

The core has successfully used shRNA expressing vector from several major companies such as Sigma, Open Biosceinces and Capital Biosciences, that offer self-contained libraries of shRNA clones pre-cloned in their proprietary vectors.

  1. pGIPZ   and its analogue   pTRIPZ   for inducible expression (Open Biosystems) express RNA under polymerase type II CMV promoter in a form of immature shRNA in the microRNA expressing cassette. These vectors offer tracking of the shRNA expression by GFP and selection of positive clones with puromycine. The pGIPZ library is available at a discounted price through the Northwestern University RNAi/Throughput Core which collaborates with DNA/RNA Delivery Core to generate shRNA expressing viruses for the NU community.
  2. pLKO   family of vectors (Sigma) that offer RNA expression in a form of the immature shRNA under polymerase type III promoter U6. PLKO vector also allow for selection of the infected cells with puromycine.
  3. pLV   vectors (Capital Biosciences) for expression of mature RNAi that does not require post-processing by DICER and DROSHA proteins. These vectors express mature RNAi duplex under U6 and H1 promoters control in a counter direction from 5'and 3' ends of the RNAi sequence. In addition these vectors offer expression of the GFP tracker and an antibiotic of resistance gene. The above bidirectional dual promoter design, allows the user to express and study function of a specific RNAi/miR in cell and animal models that lack expression of DICER and/or DROSHA, and therefore are considered to have no endogenous miRs.

 Lentiviral vectors for delivery of transcription factor Luciferase reporters

Lentiviral expressing vectors delivering DNA binding elements for transcription factors upstream of Luciferase and GFP. These vectors are analogues of well-known Luciferase reporters used throughout for transient transfections of target cells to study activity of transcription factors. To date, the Core has acquired reporters for the following transcription factors: NF-kappaB, AP1, p53, HIF1alpha, TCF/LEF, NOTCH1, Steroid response element, human Involucrin promoter, Endoplasmic stress response element.