Preclinical Milestones in MECP2 Gene Transfer for Treating Rett Syndrome.

Background: Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2). After gene transfer in mice, exogenous MeCP2 expression must be regulated to avoid dose-dependent toxicity.

Summary: The preclinical gene therapy literature for treating RTT illustrates a duly diligent progression that begins with proof-of-concept studies and advances toward the development of safer, regulated MECP2 viral genome designs.

The Efficacy of a Human-Ready mini Gene Therapy in a Pre-Clinical Model of Rett Syndrome.

Inactivating mutations and the duplication of methyl-CpG binding protein 2 (MeCP2), respectively, mediate Rett syndrome (RTT) and duplication syndrome. These disorders underscore the conceptual dose-dependent risk posed by gene therapy for mosaic RTT patients. Recently, a miRNA-Responsive Autoregulatory Element (miRARE) mitigated the dose-dependent toxicity posed by self-complementary adeno-associated viral vector serotype 9 (AAV9) mini gene therapy (scAAV9/mini) in mice.

Engineered microRNA-based regulatory element permits safe high-dose miniMECP2 gene therapy in Rett mice.

MECP2 gene transfer has been shown to extend the survival of Mecp2-/y knockout mice modelling Rett syndrome, an X-linked neurodevelopmental disorder. However, controlling deleterious overexpression of MECP2 remains the critical unmet obstacle towards a safe and effective gene therapy approach for Rett syndrome. A recently developed truncated miniMECP2 gene has also been shown to be therapeutic after AAV9-mediated gene transfer in knockout neonates.

Recent endeavors in MECP2 gene transfer for gene therapy of Rett syndrome.

Rett Syndrome (RTT) is an X chromosome-linked neurodevelopmental disorder caused by inactivating mutations in the transcription regulator methyl CpG-binding protein 2 (MeCP2). Multiple studies have independently explored the therapeutic potential of adeno-associated viral (AAV) vector-mediated MECP2 gene transfer in mouse models of RTT. Historically, the primary risk anticipated for viral vector-mediated MECP2 gene transfer in vivo has been toxicity caused by supraphysiological expression of exogenous MeCP2.

Improved Gene Therapy Extends the Survival of MeCP2-Null Mice without Apparent Toxicity after Intracisternal Delivery.

Intravenous administration of adeno-associated virus serotype 9 (AAV9)/ has been shown to extend the lifespan of mice, but this delivery route induces liver toxicity in wild-type (WT) mice. To reduce peripheral transgene expression, we explored the safety and efficacy of AAV9/ injected into the cisterna magna (ICM). AAV9/ (1 × 10 viral genomes [vg]; ICM) extended survival but aggravated hindlimb clasping and abnormal gait phenotypes.

The Role of AMPK in Drosophila melanogaster.

In the fruit fly, Drosophila melanogaster, mono-allelic expression of AMPK-α, -β, and -γ yields a single heterotrimeric energy sensor that regulates cellular and whole-body energetic homeostasis. The genetic simplicity of Drosophila, with only a single gene for each subunit, makes the fruit fly an appealing organism for elucidating the effects of AMPK mutations on signaling pathways and phenotypes. In addition, Drosophila presents researchers with an opportunity to use straightforward genetic approaches to elucidate metabolic signaling pathways that contain a level of complexity similar to that observed in mammalian pathways.

Past strategies and future directions for identifying AMP-activated protein kinase (AMPK) modulators.

AMP-activated protein kinase (AMPK) is a promising therapeutic target for cancer, type II diabetes, and other illnesses characterized by abnormal energy utilization. During the last decade, numerous labs have published a range of methods for identifying novel AMPK modulators. The current understanding of AMPK structure and regulation, however, has propelled a paradigm shift in which many researchers now consider ADP to be an additional regulatory nucleotide of AMPK.

A High Throughput Assay for Discovery of Small Molecules that Bind AMP-activated Protein Kinase (AMPK).

AMPK is a conserved heterotrimeric serine-threonine kinase that regulates anabolic and catabolic pathways in eukaryotes. Its central role in cellular and whole body metabolism makes AMPK a commonly proposed therapeutic target for illnesses characterized by abnormal energy regulation, including cancer and diabetes. Many AMPK modulators, however, produce AMPK-independent effects.

Effects of a stressor and corticotrophin releasing factor on ethanol deprivation-induced ethanol intake and anxiety-like behavior in alcohol-preferring P rats.

Rationale: Stress may elevate ethanol drinking and anxiety associated with ethanol drinking. Studies to identify relevant neurobiological substrates are needed.

Objective: To assess roles of brain regions in corticotrophin releasing factor (CRF) effects on stressor-enhanced, ethanol deprivation-induced drinking and anxiety-like behavior.