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Glycogen storage disease type III (GSDIII) is a hereditary glycogenosis caused by deficiency of the glycogen debranching enzyme (GDE), an enzyme, encoded by Agl, enabling glycogen degradation by catalyzing alpha-1,4-oligosaccharide side chain transfer and alpha-1,6-glucose cleavage. GDE deficiency causes accumulation of phosphorylase-limited dextrin, leading to liver disorder followed by fatal myopathy. Here, we tested the capacity of the new autophagosomal activator GHF-201 to alleviate disease burden by clearing pathogenic glycogen surcharge in the GSDIII mouse model Agl−/−. We used open field, grip strength, and rotarod tests for evaluating GHF-201’s effects on locomotion, a biochemistry panel to quantify hematological biomarkers, indirect calorimetry to quantify in vivo metabolism, transmission electron microscopy to quantify glycogen in muscle, and fibroblast image analysis to determine cellular features affected by GHF-201. GHF-201 was able to improve all locomotion parameters and partially reversed hypoglycemia, hyperlipidemia and liver and muscle malfunction in Agl−/− mice. Treated mice burnt carbohydrates more efficiently and showed significant improvement of aberrant ultrastructural muscle features. In GSDIII patient fibroblasts, GHF-201 restored mitochondrial membrane polarization and corrected lysosomal swelling. In conclusion, GHF-201 is a viable candidate for treating GSDIII as it recovered a wide range of its pathologies in vivo, in vitro, and ex vivo.

Injury to the central nervous system induces neuronal cell death and astrogliosis, an astrocyte-mediated response that has both a beneficial and detrimental impact on surrounding neuronal cells. The circumstance however, in which astrogliosis improves neuronal survival after an injury is not fully characterized. We have recently shown that Semaphorin4B (Sema4B) in the cortex is mostly expressed by astrocytes, and in its absence, astrocyte activation after an injury is altered. Here we find that in Sema4B knockout mice, neuronal cell death is reduced; as a result, more neurons survive near the injury site. Sema4B protein applied directly to neurons does not affect neuronal survival. In contrast, survival of wild-type neurons is increased when plated on glial culture isolated from the Sema4B knockout mice, as compared to Sema4B heterozygous cultures. Furthermore, this increased survival is also observed with conditioned medium collected from glial cultures of Sema4B knockout mice compared to heterozygous mice. This indicates that the increased survival is glial cell-dependent and mediated by a secreted factor(s). Together, our results imply that following injury, the lack of Sema4B expression in glial cells improves neuronal survival either as a result of reduced toxic factors, or perhaps increased survival factors under these conditions.

Abstract This work employs adult polyglucosan body disease (APBD) models to explore the efficacy and mechanism of action of the polyglucosan‐reducing compound 144DG11. APBD is a glycogen storage disorder (GSD) caused by glycogen branching enzyme (GBE) deficiency causing accumulation of poorly branched glycogen inclusions called polyglucosans. 144DG11 improved survival and motor parameters in a GBE knockin (Gbeys/ys) APBD mouse model. 144DG11 reduced polyglucosan and glycogen in brain, liver, heart, and peripheral nerve. Indirect calorimetry experiments revealed that 144DG11 increases carbohydrate burn at the expense of fat burn, suggesting metabolic mobilization of pathogenic polyglucosan. At the cellular level, 144DG11 increased glycolytic, mitochondrial, and total ATP production. The molecular target of 144DG11 is the lysosomal membrane protein LAMP1, whose interaction with the compound, similar to LAMP1 knockdown, enhanced autolysosomal degradation of glycogen and lysosomal acidification. 144DG11 also enhanced mitochondrial activity and modulated lysosomal features as revealed by bioenergetic, image‐based phenotyping and proteomics analyses. As an effective lysosomal targeting therapy in a GSD model, 144DG11 could be developed into a safe and efficacious glycogen and lysosomal storage disease therapy.

Obesity and hyperglycemia are risk factors for cognitive decline and for the development of Alzheimer’s Disease (AD). Bariatric surgery is an effective treatment for obesity that was shown to improve cognitive decline in obese patients. Bariatric surgery was shown to exert weight loss independent effects on metabolic diseases such as type 2 diabetes. We tested whether sleeve gastrectomy (SG), a common bariatric surgery, can affect the cognitive impairment in lean, normoglycemic female 5xFAD mice, a genetic model for AD. 5xFAD mice and wild-type (WT) littermates underwent SG or sham surgery at the age of 5 months and were tested for metabolic, behavioral, and molecular phenotypes 90 days later. SG led to a reduction in blood glucose levels and total plasma cholesterol levels in 5xFAD mice without inducing weight loss. However, the surgery did not affect the outcomes of long-term spatial memory tests in these mice. Analysis of β-Amyloid plaques corroborated the behavioral studies in showing no effect of surgery on the molecular phenotype of 5xFAD mice. In conclusion, SG leads to an improved metabolic profile in lean female 5xFAD mice without inducing weight loss but does not affect the brain pathology or behavioral phenotype. Our results suggest that the positive effects of bariatric surgery on cognitive decline in obese patients are likely attributed to weight loss and improvement in obesity sequelae, and not to weight loss independent effects of surgery.

We recently reported the benefit of the IV transferring of active exogenous mitochondria in a short-term pharmacological AD (Alzheimer’s disease) model. We have now explored the efficacy of mitochondrial transfer in 5XFAD transgenic mice, aiming to explore the underlying mechanism by which the IV-injected mitochondria affect the diseased brain. Mitochondrial transfer in 5XFAD ameliorated cognitive impairment, amyloid burden, and mitochondrial dysfunction. Exogenously injected mitochondria were detected in the liver but not in the brain. We detected alterations in brain proteome, implicating synapse-related processes, ubiquitination/proteasome-related processes, phagocytosis, and mitochondria-related factors, which may lead to the amelioration of disease. These changes were accompanied by proteome/metabolome alterations in the liver, including pathways of glucose, glutathione, amino acids, biogenic amines, and sphingolipids. Altered liver metabolites were also detected in the serum of the treated mice, particularly metabolites that are known to affect neurodegenerative processes, such as carnosine, putrescine, C24:1-OH sphingomyelin, and amino acids, which serve as neurotransmitters or their precursors. Our results suggest that the beneficial effect of mitochondrial transfer in the 5XFAD mice is mediated by metabolic signaling from the liver via the serum to the brain, where it induces protective effects. The high efficacy of the mitochondrial transfer may offer a novel AD therapy.

Background: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects motor neurons (MNs). It was shown that human astrocytes with mutations in genes associated with ALS, like C9orf72 (C9) or SOD1, reduce survival of MNs. Astrocyte toxicity may be related to their dysfunction or the release of neurotoxic factors. Methods: We used human induced pluripotent stem cell-derived astrocytes from ALS patients carrying C9orf72 mutations and non-affected donors. We utilized these cells to investigate astrocytic induced neuronal toxicity, changes in astrocyte transcription profile as well as changes in secretome profiles. Findings: We report that C9-mutated astrocytes are toxic to MNs via soluble factors. The toxic effects of astrocytes are positively correlated with the length of astrocyte propagation in culture, consistent with the age-related nature of ALS. We show that C9-mutated astrocytes downregulate the secretion of several antioxidant proteins. In line with these findings, we show increased astrocytic oxidative stress and senescence. Importantly, media conditioned by C9-astrocytes increased oxidative stress in wild type MNs. Interpretation: Our results suggest that dysfunction of C9-astrocytes leads to oxidative stress of themselves and MNs, which probably contributes to neurodegeneration. Our findings suggest that therapeutic strategies in familial ALS must not only target MNs but also focus on astrocytes to abrogate nervous system injury. Keywords: Amyotrophic lateral sclerosis, iPSC, Astrocytes, Oxidative stress, Neurotoxicity, Senescence

Axon guidance molecules determine the pattern of neuronal circuits. Accuracy of the process is ensured by unknown mechanisms that correct early guidance errors. Since the time frame of error correction in Sema3A null mice partly overlaps with the period of naturally occurring cell death in dorsal root ganglia (DRG) development, we tested the hypothesis that apoptosis of misguided neurons enables error correction. We crossed BAX null mice, in which DRG apoptosis is blocked, with Sema3A null mice to induce errors. Analyses of these double-null mouse embryos showed that the elimination of abnormal projections is not blocked in the absence of BAX. Surprisingly however, there are fewer surviving neurons in Sema3A null or Sema3A/BAX double-null newborn mice than in wild-type mice. These results suggest that guidance errors are corrected by a BAX-independent cell death mechanism. Thus, aberrant axonal guidance may lead to reductions in neuronal numbers to suboptimal levels, perhaps increasing the likelihood of neuropathological consequences later in life.