Efficacious Androgen Hormone Administration in Combination with Adeno-Associated Virus Vector-Mediated Gene Therapy in Female Mice with Pompe Disease

Pompe disease is an autosomal recessive lysosomal storage disorder caused by deficiency of acid α-glucosidase (GAA), resulting in skeletal muscle weakness and cardiomyopathy that progresses despite currently available therapy in some patients. The development of gene therapy with adeno-associated virus (AAV) vectors revealed a sex-dependent decrease in efficacy in female mice with Pompe disease. This study evaluated the effect of testosterone on gene therapy with an AAV2/8 vector containing a liver-specific promoter to drive expression of GAA (AAV2/8-LSPhGAA) in female GAA-knockout (KO) mice that were implanted with pellets containing testosterone propionate before vector administration. Six weeks after treatment, neuromuscular function and muscle strength were improved as demonstrated by increased Rotarod and wirehang latency for female mice treated with testosterone and vector, in comparison with vector alone. Biochemical correction improved after the addition of testosterone as demonstrated by increased GAA activity and decreased glycogen content in the skeletal muscles of female mice treated with testosterone and vector, in comparison with vector alone. An alternative androgen, oxandrolone, was evaluated similarly to reveal increased GAA in the diaphragm and extensor digitorum longus of female GAA-KO mice after oxandrolone administration; however, glycogen content was unchanged by oxandrolone treatment. The efficacy of androgen hormone treatment in females correlated with increased mannose-6-phosphate receptor in skeletal muscle. These data confirmed the benefits of brief treatment with an androgen hormone in mice with Pompe disease during gene therapy.

A single phenylalanine residue in β-arrestin2 critically regulates its binding to G protein-coupled receptors

Arrestins and their yeast homologs, arrestin-related trafficking adaptors (ARTs), share a stretch of 29 amino acids called the ART motif. However, the functionality of that motif is unknown. We now report that deleting this motif prevents agonist-induced ubiquitination of β-arrestin2 (β-arr2) and blocks its association with activated G protein–coupled receptors (GPCRs). Within the ART motif, we have identified a conserved phenylalanine residue, Phe116, that is critical for the formation of β-arr2–GPCR complexes. β-arr2 Phe116Ala mutant has negligible effect on blunting β₂-adrenergic receptor–induced cAMP generation unlike β-arr2, which promotes rapid desensitization. Furthermore, available structures for inactive and inositol hexakisphosphate 6–activated forms of bovine β-arr2 revealed that Phe116 is ensconced in a hydrophobic pocket, whereas the adjacent Phe117 and Phe118 residues are not. Mutagenesis of Phe117 and Phe118, but not Phe116, preserves GPCR interaction of β-arr2. Surprisingly, Phe116 is dispensable for the association of β-arr2 with its non-GPCR partners. β-arr2 Phe116Ala mutant presents a significantly reduced protein half-life compared with β-arr2 and undergoes constitutive Lys-48-linked polyubiquitination, which tags proteins for proteasomal degradation. We also found that Phe116 is critical for agonist-dependent β-arr2 ubiquitination with Lys-63-polyubiquitin linkages that are known mediators of protein scaffolding and signal transduction. Finally, we have shown that β-arr2 Phe116Ala interaction with activated β₂-adrenergic receptor can be rescued with an in-frame fusion of ubiquitin. Taken together, we conclude that Phe116 preserves structural stability of β-arr2, regulates the formation of β-arr2–GPCR complexes that inhibit G protein signaling, and promotes subsequent ubiquitin-dependent β-arr2 localization and trafficking.

Minimum Effective Dose to Achieve Biochemical Correction With AAV Vector-Mediated Gene Therapy in Mice With Pompe Disease

Pompe disease is an autosomal recessive lysosomal storage disorder caused by deficiency of acid α-glucosidase (GAA), resulting in skeletal muscle weakness and cardiomyopathy. Muscle weakness progresses despite currently available therapy, which has prompted the development of gene therapy with adeno-associated virus (AAV) type 2 vectors cross-packaged as AAV8 (2/8). Preclinical studies of gene therapy demonstrated that the minimum effective dose for biochemical correction with AAV2/8-LSPhGAA was approximately 2 x 1011 vector genomes (vg)/kg body weight. The current study examined the transduction of AAV2/8-LSPeGFP vector in adult GAA-KO mice with Pompe disease, and correlated that degree of transduction with the biochemical correction achieved by the same dose of AAV2/8-LSPhGAA. The minimum effective dose was found to be approximately 2 x 1011 vg/kg, with all hepatocytes variably transducing at this dose. At this dose, liver GAA significantly increased, while liver glycogen significantly decreased. The 2 x 1011 vg/kg dose was sufficient to significantly decrease diaphragm glycogen. However, the heart, diaphragm, and quadriceps all required a four-fold higher dose to achieve correction of GAA deficiency in association with significant clearance of stored glycogen, which correlated with increased serum GAA activity. These data indicate that AAV2/8-LSPeGFP transduced all hepatocytes when the 2 x 1011 vg/kg dose was administered, which correlated with partial biochemical correction from the equivalent dose of AAV2/8-LSPhGAA. Together these data support the conclusion that substantial transduction of the liver is required to achieve biochemical correction from AAV2/8-LSPhGAA.

Comparisons of Infant and Adult Mice Reveal Age Effects for Liver Depot Gene Therapy in Pompe Disease

Pompe disease is caused by the deficiency of lysosomal acid α-glucosidase (GAA). It is expected that gene therapy to replace GAA with adeno-associated virus (AAV) vectors will be less effective early in life because of the rapid loss of vector genomes. AAV2/8-LSPhGAA (3 × 1010 vector genomes [vg]/mouse) was administered to infant (2-week-old) or adult (2-month-old) GAA knockout mice. AAV vector transduction in adult mice significantly corrected GAA deficiency in the heart (p < 0.0001), diaphragm (p < 0.01), and quadriceps (p < 0.001) for >50 weeks. However, in infant mice, the same treatment only partially corrected GAA deficiency in the heart (p < 0.05), diaphragm (p < 0.05), and quadriceps (p < 0.05). The clearance of glycogen was much more efficient in adult mice compared with infant mice. Improved wire hang test latency was observed for treated adults (p < 0.05), but not for infant mice. Abnormal ventilation was corrected in both infant and adult mice. Vector-treated female mice demonstrated functional improvement, despite a lower degree of biochemical correction compared with male mice. The relative vector dose for infants was approximately 3-fold higher than adults, when normalized to body weight at the time of vector administration. Given these data, the dose requirement to achieve similar efficacy will be higher for the treatment of young patients.

Low-Dose Liver-Targeted Gene Therapy for Pompe Disease Enhances Therapeutic Efficacy of ERT via Immune Tolerance Induction

Pompe disease results from acid α-glucosidase (GAA) deficiency, and enzyme replacement therapy (ERT) with recombinant human (rh) GAA has clinical benefits, although its limitations include the short half-life of GAA and the formation of antibody responses. The present study compared the efficacy of ERT against gene transfer with an adeno-associated viral (AAV) vector containing a liver-specific promoter. GAA knockout (KO) mice were administered either a weekly injection of rhGAA (20 mg/kg) or a single injection of AAV2/8-LSPhGAA (8 × 10¹¹ vector genomes [vg]/kg). Both treatments significantly reduced glycogen content of the heart and diaphragm. Although ERT triggered anti-GAA antibody formation, there was no detectable antibody response following AAV vector administration. The efficacy of three lower dosages of AAV2/8-LSPhGAA was evaluated in GAA-KO mice, either alone or in combination with ERT. The minimum effective dose (MED) identified was 8 × 10¹⁰ vg/kg to reduce glycogen content in the heart and diaphragm of GAA-KO mice. A 3-fold higher dose was required to suppress antibody responses to ERT. Efficacy from liver gene therapy was slightly greater in male mice than in female mice. Vector dose correlated inversely with anti-GAA antibody formation, whereas higher vector doses suppressed previously formed anti-GAA antibodies as late as 25 weeks after the start of ERT and achieved biochemical correction of glycogen accumulation. In conclusion, we identified the MED for effective AAV2/8-LSPhGAA-mediated tolerogenic gene therapy in Pompe disease mice.

Synergistic Efficacy from Gene Therapy with Coreceptor Blockade and a β2-Agonist in Murine Pompe Disease

Pompe disease (glycogen storage disease type II; acid maltase deficiency) is a devastating myopathy resulting from acid α-glucosidase (GAA) deficiency in striated and smooth muscle. Despite the availability of enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA), the limitations of ERT have prompted the preclinical development of gene therapy. Gene therapy has the advantage of continuously producing GAA, in contrast to ERT, which requires frequent injections of rhGAA. An adeno-associated viral (AAV) vector containing a muscle-specific promoter, AAV-MHCK7hGAApA, achieved high GAA expression in heart and skeletal muscle in mice with Pompe disease. However, elevated GAA activity was not sufficient to completely clear accumulated glycogen in skeletal muscle. The process of glycogen clearance from lysosomes might require improved trafficking of GAA to the lysosomes in skeletal muscle, previously achieved with the β(2)-agonist clenbuterol that enhanced glycogen clearance in skeletal muscle without increasing GAA activity. Glycogen clearance was clearly enhanced by treatment with a nondepleting anti-CD4 monoclonal antibody (anti-CD4 mAb) along with muscle-specific GAA expression in cardiac muscle, but that treatment was not effective in skeletal muscle. Furthermore, anti-CD4 mAb treatment along with clenbuterol achieved synergistic therapeutic efficacy in both cardiac and skeletal muscle. This triple therapy increased both muscle strength and weight gain. Overall, triple therapy to enhance GAA trafficking and to suppress immune responses significantly improved the efficacy of muscle-targeted gene therapy in murine Pompe disease.

Enhanced efficacy from gene therapy in Pompe disease using coreceptor blockade

Enzyme replacement therapy (ERT) is the standard-of-care treatment of Pompe disease, a lysosomal storage disorder caused by deficiency of acid α-glucosidase (GAA). One limitation of ERT with recombinant human (rh) GAA is antibody formation against GAA. Similarly, in adeno-associated virus (AAV) vector-mediated gene transfer for Pompe disease, development of antibodies against the GAA transgene product and the AAV vector prevents therapeutic efficacy and vector readministration, respectively. Here a nondepleting anti-CD4 monoclonal antibody (mAb) was administrated intravenously prior to administration of an AAV2/9 vector encoding GAA to suppress anti-GAA responses, leading to a substantial reduction of anti-GAA immunoglobulins, including IgG1, IgG2a, IgG2b, IgG2c, and IgG3. Transduction efficiency in liver with a subsequent AAV2/8 vector was massively improved by the administration of anti-CD4 mAb with the initial AAV2/9 vector, indicating a spread of benefit derived from control of the immune response to the first AAV2/9 vector. Anti-CD4 mAb along with AAV2/9-CBhGAApA significantly increased GAA activity in heart and skeletal muscles along with a significant reduction of glycogen accumulation. Taken together, these data demonstrated that the addition of nondepleting anti-CD4 mAb with gene therapy controls humoral immune responses to both vector and transgene, resulting in clear therapeutic benefit in mice with Pompe disease.

MARCH2 promotes endocytosis and lysosomal sorting of carvedilol-bound β(2)-adrenergic receptors

The β₂-adrenergic receptor antagonist carvedilol recruits MARCH2, a unique E3 ubiquitin ligase, to promote receptor endocytosis and lysosomal trafficking.

Lysosomal degradation of ubiquitinated β₂-adrenergic receptors (β₂ARs) serves as a major mechanism of long-term desensitization in response to prolonged agonist stimulation. Surprisingly, the βAR antagonist carvedilol also induced ubiquitination and lysosomal trafficking of both endogenously expressed β₂ARs in vascular smooth muscle cells (VSMCs) and overexpressed Flag-β₂ARs in HEK-293 cells. Carvedilol prevented β₂AR recycling, blocked recruitment of Nedd4 E3 ligase, and promoted the dissociation of the deubiquitinases USP20 and USP33. Using proteomics approaches (liquid chromatography–tandem mass spectrometry), we identified that the E3 ligase MARCH2 interacted with carvedilol-bound β₂AR. The association of MARCH2 with internalized β₂ARs was stabilized by carvedilol and did not involve β-arrestin. Small interfering RNA–mediated down-regulation of MARCH2 ablated carvedilol-induced ubiquitination, endocytosis, and degradation of endogenous β₂ARs in VSMCs. These findings strongly suggest that specific ligands recruit distinct E3 ligase machineries to activated cell surface receptors and direct their intracellular itinerary. In response to β blocker therapy with carvedilol, MARCH2 E3 ligase activity regulates cell surface β₂AR expression and, consequently, its signaling.

Activin A induces ovine follicle stimulating hormone beta using -169/-58 bp of its promoter and a simple TATA box

BACKGROUND

Activin A increases production of follicle stimulating hormone (FSH) by inducing transcription of its beta subunit (FSHB). This induction has been studied here in LbetaT2 gonadotropes using transient expression of ovine FSHBLuc (-4741 bp of ovine FSHB promoter plus exon/intron 1 linked to Luc). Several sequences between -169/-58 bp of the ovine FSHB proximal promoter are necessary for induction by activin A in LbetaT2 cells, but deletions between -4741/-752 bp decrease induction > 70% suggesting the existence of other important 5' sequences. Induction disappears if a minimal T81 thymidine kinase promoter replaces the ovine FSHB TATA box and 3' exon/intron. The study reported here was designed to determine if sequences outside -169/-58 bp are important for induction of ovine FSHB by activin A.

METHODS

Progressively longer deletions of ovine FSHBLuc were created between -4741/-195 bp. Deletions internal to this region were created also, but replaced with substitute DNA. The ovine FSHB TATA box region (-40/+3 bp) was replaced by thymidine kinase and rat prolactin minimal promoters, and substitutions were made in 3' intron/exon sequences. All constructs were tested for basal and activin A-induced expression in LbetaT2 cells.

RESULTS

Successive 5' deletions progressively lowered fold-induction by activin A from 9.5 to zero, but progressively increased basal expression. Replacing deletions with substitute DNA showed no changes in basal expression or fold-induction. Induction by activin A was supported by the minimal rat prolactin promoter (TATA box) but not the thymidine kinase promoter (no TATA box). Replacement mutations in the 3' region did not decrease induction by activin A.

CONCLUSION

The data show that specific ovine FSHB sequences 5' to -175 bp or 3' of the transcription start site are not required for induction by activin A. A minimal TATA box promoter supports induction by activin A, but the sequence between the TATA box and transcription start site seems unimportant.

Chronic gonadotropin-releasing hormone inhibits activin induction of the ovine follicle-stimulating hormone beta-subunit: involvement of 3',5'-cyclic adenosine monophosphate response element binding protein and nitric oxide synthase type I

FSH is induced by activin, and this expression is modulated by GnRH through FSHB expression. This report focuses on the inhibitory effect of GnRH on activin-induced FSHB expression. Activin-treated primary murine pituitary cultures robustly express mutant ovine FSHBLuc-DeltaAP1, a luciferase transgene driven by 4.7 kb of ovine FSHB promoter. This promoter lacks two GnRH-inducible activator protein-1 sites, making it easier to observe GnRH-mediated inhibition. Luciferase expression from this transgene was decreased 94% by 100 nM GnRH with a half-time of approximately 4 h in pituitary cultures, and this inhibition was independent of follistatin. Activators of cAMP and protein kinase C like forskolin and phorbol 12-myristate 3-acetate (PMA), respectively, mimicked GnRH action. Kinetic studies of wild-type ovine FSHBLuc in LbetaT2 cells showed continuous induction by activin (4-fold) over 20 h. Most of this induction (78%) was blocked, beginning at 6 h. cAMP response element binding protein (CREB) was implicated in this inhibition because overexpression of its constitutively active mutant mimicked GnRH, and its inhibitor (inducible cAMP early repressor isoform II) reversed the inhibition caused by GnRH, forskolin, or PMA. In addition, GnRH, forskolin, or PMA increased the expression of a CREB-responsive reporter gene, 6xCRE-37PRL-Luc. Inhibition of nitric oxide type I (NOSI) by 7-nitroindazole also reversed GnRH-mediated inhibition by 60%. It is known that GnRH and CREB induce production of NOSI in gonadotropes and neuronal cells, respectively. These data support the concept that chronic GnRH inhibits activin-induced ovine FSHB expression by sequential activation of CREB and NOSI through the cAMP and/or protein kinase C pathways.

Tumor regression by repeated intratumoral delivery of water soluble lipopolymers/p2CMVmIL-12 complexes

The recruitment of the body's own immune system is amongst the most potent defenses known against cancer. Recent attempts to harness this response have enlisted the use of the immune modulating cytokine, interleukin-12 (IL-12). The objective of this work is to investigate the organ distribution and anti-tumor response in vivo after intratumoral administration of IL-12 expression plasmid complexed with water soluble lipopolymer (WSLP). Formulations of WSLP/p2CMVmIL-12 at N/P mol ratio of 20:1 were prepared in the presence of 5% (w/v) glucose. Organ distribution data following intratumoral injection of CT-26 subcutaneous tumor-bearing BALB/c mice demonstrated enhanced retention of WSLP/p2CMVmIL-12 complexes within the tumor and limited accumulation in other organs for up to 96 h. Tumor-bearing BALB/c mice received either single or repeated intratumoral injections at 4- or 8-day intervals to examine the efficacy of single versus repeated injections on tumor regression and survival. Significant tumor growth inhibition during 4- and 8-day injection trials was observed with maximal survival in mice receiving 4-day injections of WSLP/p2CMVmIL-12 complexes. In conclusion, the water-soluble non-toxic lipopolymer complexed with p2CMVIL-12 showed enhanced transgene expression in vivo, inhibits the rate of tumor growth, and significantly increases survival.

Artery wall binding peptide-poly(ethylene glycol)-grafted-poly(L-lysine)-based gene delivery to artery wall cells

Artery wall binding peptide (AWBP; Cys-Gly-Arg-Ala-Leu-Val-Asp-Thr-Leu-Lys-Phe-Val-Thr-Gln-Ala-Glu-Gly-Ala-Lys), a specific targeting peptide, was conjugated to poly(ethylene glycol)-grafted-poly(L-lysine) (PEG-g-PLL) to enhance the gene transfer to artery wall cells. AWBP-PEG-PLL was synthesized by the reaction between the vinylsulfone group of PEG-g-PLL and the thiol group of cysteine in AWBP. 1H-NMR analysis confirmed the composition of the obtained polymer and indicated that four mol of AWBP were reacted to one mole of VS-PEG-PLL. The particles of AWBP-PEG-PLL/pDNA complexes were determined spherical with a size of approximately 100 nm by dynamic light scattering (DLS) and atomic force microscopy (AFM). Agarose gel retardation assay indicated that AWBP-PEG-PLL was able to condense plasmid DNA and reach complete complexation at and above a charge ratio 1/1 (+/-). Transfection efficiency of AWBP-PEG-PLL/pDNA complexes was 150-180 times higher than that of control systems, such as PEG-g-PLL/pDNA and PLL/pDNA, in both bovine aorta endothelial cells and smooth muscle cells. Luciferase activities of AWBP-PEG-PLL depended on the amount of free AWBP, while those of the control carriers such as PLL and PEG-g-PLL were not affected by free AWBP. These results supported that gene transfer of AWBP-PEG-PLL/pDNA complexes to bovine aorta wall cells was mediated by specific artery wall cell receptor-mediated endocytosis.

Repression of GAD autoantigen expression in pancreas beta-Cells by delivery of antisense plasmid/PEG-g-PLL complex

It was previously reported that silencing of the expression of glutamic acid decarboxylase (GAD) in transgenic nonobese diabetic (NOD) mice completely protected islet beta-cells against development of diabetes. This suggests that the repression of GAD autoantigen by somatic gene delivery can prevent autoimmune destruction of pancreatic beta-cells. To repress GAD expression in islet beta-cells, we delivered an antisense GAD mRNA expression plasmid (pRIP-AS-GAD) using poly(ethylene glycol)-grafted poly-L-lysine (PEG-g-PLL) as a gene carrier. In a gel retardation assay, the pRIP-AS-GAD/PEG-g-PLL complex was completely retarded above a weight ratio of 1:1.5 (plasmid: PEG-g-PLL). PEG-g-PLL protected the plasmid DNA from DNase I for more than 60 minutes. In a reporter gene transfection assay, PEG-g-PLL showed the highest transfection efficiency at a weight ratio of 1:3. We also transfected pRIP-AS-GAD/PEG-g-PLL complex into a GAD-producing mouse insulinoma (MIN6) cell line. The antisense mRNA was expressed specifically in beta-cells and expression was dependent on glucose level. The repression of GAD after transfection of pRIP-AS-GAD was confirmed by immunoblot assay. In addition, in vivo expression of antisense RNA in pancreas was confirmed by RT-PCR after intravenous injection of the complex into mice. Therefore, our study revealed that the pRIP-AS-GAD/PEG-g-PLL system is applicable for the repression of GAD autoantigen expression.

TerplexDNA gene carrier system targeting artery wall cells

The development of non-viral gene carrier systems becomes more urgent and important due to the major biosafety considerations involved with application of viral vector systems for clinical gene therapy. We recently developed a novel non-viral gene carrier system, termed TerplexDNA, which showed high gene transfer efficiency when compared to the lipofectamine gene delivery system both in HepG2 and A7R5 cell lines in vitro. In present studies, we demonstrated that the TerplexDNA gene carrier system specifically delivered the reporter genes (LacZ and Luciferase) and therapeutic gene (hrVEGF(165) cDNA) into bovine aortic artery wall cells (endothelial cells and smooth muscle cells) by receptor mediated endocytosis. We found that the transfection efficiency to these primary artery wall cells, when mediated by the TerplexDNA system, was dose-dependent, saturable and was significantly inhibited by excess free LDL. The transfection efficiency of the TerplexDNA gene carrier system was approximately 60-fold higher than that of the lipofectamine gene carrier system. The TerplexDNA gene carrier system is a useful and promising tool for artery wall gene transfer.

Biodegradable polyester, poly[alpha-(4-aminobutyl)-L-glycolic acid], as a non-toxic gene carrier

PURPOSE

The aim of this study was to develop a non-toxic polymeric gene carrier. For this purpose, biodegradable cationic polymer, poly[alpha-(4-aminobutyl)-L-glycolic acid] (PAGA) was synthesized. PAGA was designed to have ester linkage because polyesters usually show biodegradability.

METHODS

Degradation of PAGA in an aqueous solution was followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). PAGA/DNA complexes were characterized by gel electrophoresis, atomic force microscopy (AFM), dynamic light scattering (DLS). The transfection was measured by using the beta-galactosidase reporter gene.

RESULTS

PAGA was degraded in aqueous solution very quickly and the final degradation product was a monomer (L-oxylysine). Formation of self-assembling biodegradable complexes between PAGA and DNA at a charge ratio 1:1 (+/-) was confirmed by gel band shift assay and AFM. In these studies, controlled release of DNA from the complexes could be seen. The complexes showed about 2-fold higher transfection efficiency than DNA complexes of poly-L-lysine (PLL), a structural analogue of PAGA, which is the most commonly used poly-cation for gene delivery. The polymer did not show cytotoxicity, possibly because of its degradability and the biocompatibility of the monomer.

CONCLUSIONS

The use of the biodegradable poly-cation, PAGA, as a DNA condensing agent will be useful in safe gene delivery.