Tommaso Vannocci, Roberto Notario Manzano, Ombretta Beccalli, Barbara Bettegazzi, Fabio Grohovaz, Gianfelice Cinque, Antonio de Riso, Luca Quaroni, Franca Codazzi, Annalisa Pastore
Disease Models & Mechanisms 2018 : dmm.032706 doi: 10.1242/dmm.032706 Published 24 May 2018
We prove that overexpression of the frataxin gene affects the cellular metabolism. It also lead to a significant increase of oxidative stress and labile iron pool levels. These cellular alterations are similar to those observed when the gene is partially silenced, as it occurs in Friedreich's ataxia's patients. Our data suggest that the levels of frataxin must be tightly regulated and fine-tuned, any imbalance leading to oxidative stress and toxicity.
Viral approaches (AAV), take advantage of a human exogenous FXN gene under the control of strong promoters that induce overexpression of the therapeutic genes. Although the mouse models showed great improvements, the lack of a tight control on the levels of expression could generate the effects detailed in this work with unknown long-term consequences for patients treated this way. Recent studies have taken advantage of the novel CRISPR gene editing approach to produce the desired gene correction as an alternative, gene correction of the endogenous FXN gene by reduction of the GAA expansion seems to be preferable. This strategy has the advantage that frataxin levels would be restored to physiological levels. It is however essential for these studies to determine the effects of different levels of frataxin.
Wednesday, June 6, 2018
Rehabilitation robots for the treatment of sensorimotor deficits: a neurophysiological perspective
Roger Gassert and Volker Dietz; Journal of NeuroEngineering and Rehabilitation 2018 15:46 doi:10.1186/s12984-018-0383-x
Future rehabilitation approaches will not only profit from the inclusion of robots, but also from an advanced understanding of neurophysiological mechanisms underlying normal and impaired sensorimotor functions, enabled by the use of robots as scientific tools. Resulting insights will benefit the development of advanced rehabilitation robots, and further promote collaboration between engineers, therapists and clinical neurophysiologists.
Future rehabilitation approaches will not only profit from the inclusion of robots, but also from an advanced understanding of neurophysiological mechanisms underlying normal and impaired sensorimotor functions, enabled by the use of robots as scientific tools. Resulting insights will benefit the development of advanced rehabilitation robots, and further promote collaboration between engineers, therapists and clinical neurophysiologists.
Oligonucleotides Hold Promise as a Therapy for Friedreich's Ataxia: Friedreich's ataxia currently is incurable, but synthetic antisense oligonucleotides have demonstrated promising results in increasing frataxin gene expression and restoring it to normal levels
AJMG. Volume176, Issue6 June 2018 Pages 1282-1282 doi:10.1002/ajmg.a.38850
Another important point that was demonstrated in this and previous papers is that oligonucleotides increase the expression of FXN. According to Dr. Corey, “That corrects a fundamental defect in the disease specifically at the gene level, so it is a plausible compound for moving forward.”
However, right now the compounds are in the earliest stages, and more evidence is needed that the treatment is safe and effective. “We need to find animal models to begin testing it, and a company needs to be encouraged to develop it,” Dr. Corey says.
Another important point that was demonstrated in this and previous papers is that oligonucleotides increase the expression of FXN. According to Dr. Corey, “That corrects a fundamental defect in the disease specifically at the gene level, so it is a plausible compound for moving forward.”
However, right now the compounds are in the earliest stages, and more evidence is needed that the treatment is safe and effective. “We need to find animal models to begin testing it, and a company needs to be encouraged to develop it,” Dr. Corey says.
Sunday, June 3, 2018
Modelling the dorsal root ganglia using human pluripotent stem cells: A platform to study peripheral neuropathies
Serena Viventi, Mirella Dottori, The International Journal of Biochemistry & Cell Biology, Volume 100, July 2018, Pages 61-68, ISSN 1357-2725, doi:10.1016/j.biocel.2018.05.005.
Sensory neurons of the dorsal root ganglia (DRG) are the primary responders to stimuli inducing feelings of touch, pain, temperature, vibration, pressure and muscle tension. They consist of multiple subpopulations based on their morphology, molecular and functional properties. Our understanding of DRG sensory neurons has been predominantly driven by rodent studies and using transformed cell lines, whereas less is known about human sensory DRG neurons simply because of limited availability of human tissue. Although these previous studies have been fundamental for our understanding of the sensory system, it is imperative to profile human DRG subpopulations as it is becoming evident that human sensory neurons do not share the identical molecular and functional properties found in other species. Furthermore, there are wide range of diseases and disorders that directly/indirectly cause sensory neuronal degeneration or dysfunctionality. Having an in vitro source of human DRG sensory neurons is paramount for studying their development, unique neuronal properties and for accelerating regenerative therapies to treat sensory neuropathies. Here we review the major studies describing generation of DRG sensory neurons from human pluripotent stem cells and fibroblasts and the gaps that need to be addressed for using in vitro-generated human DRG neurons to model human DRG tissue.
There are vast ranges of diseases and conditions, usually progressive, which can affect DRG sensory neurons. The underlying causes of DRG degeneration may be either directly intrinsic to DRG neurons or indirectly associated with other pathologies. Some inherited genetic diseases inducing DRG degeneration include Friedreich’s Ataxia and Charcot Marie Tooth Disease
Sensory neurons of the dorsal root ganglia (DRG) are the primary responders to stimuli inducing feelings of touch, pain, temperature, vibration, pressure and muscle tension. They consist of multiple subpopulations based on their morphology, molecular and functional properties. Our understanding of DRG sensory neurons has been predominantly driven by rodent studies and using transformed cell lines, whereas less is known about human sensory DRG neurons simply because of limited availability of human tissue. Although these previous studies have been fundamental for our understanding of the sensory system, it is imperative to profile human DRG subpopulations as it is becoming evident that human sensory neurons do not share the identical molecular and functional properties found in other species. Furthermore, there are wide range of diseases and disorders that directly/indirectly cause sensory neuronal degeneration or dysfunctionality. Having an in vitro source of human DRG sensory neurons is paramount for studying their development, unique neuronal properties and for accelerating regenerative therapies to treat sensory neuropathies. Here we review the major studies describing generation of DRG sensory neurons from human pluripotent stem cells and fibroblasts and the gaps that need to be addressed for using in vitro-generated human DRG neurons to model human DRG tissue.
There are vast ranges of diseases and conditions, usually progressive, which can affect DRG sensory neurons. The underlying causes of DRG degeneration may be either directly intrinsic to DRG neurons or indirectly associated with other pathologies. Some inherited genetic diseases inducing DRG degeneration include Friedreich’s Ataxia and Charcot Marie Tooth Disease
Tuesday, May 29, 2018
TLR-activated repression of Fe-S cluster biogenesis drives a metabolic shift and alters histone and tubulin acetylation
Wing-Hang Tong, Nunziata Maio, De-Liang Zhang, Erika M. Palmieri, Hayden Ollivierre, Manik C. Ghosh, Daniel W. McVicar and Tracey A. Rouault; Blood Advances 2018 2:1146-1156; doi: doi:10.1182/bloodadvances.2018015669
hese results reveal new regulatory pathways and novel roles of the Fe-S cluster biogenesis machinery in modifying the epigenome and acetylome and provide new insights into the etiology of Fe-S cluster biogenesis disorders.
Interestingly, we showed that silencing of FXN and ISCU resulted in increased MEC17 levels and increased α-tubulin acetylation.
Extensive chromatin immunoprecipitation data collected at the FRDA locus, which contains an expanded trinucleotide repeat (GAA)n in the first intron of FXN, had shown that the levels of the heterochromatin mark H3K9me3 were enriched, whereas the levels of acetylated H3 and H4 were reduced. Our finding that decreased Fe-S cluster biogenesis resulted in decreased overall histone acetylation and increased H3K9me3 levels poses an interesting possibility of a negative feedback mechanism that potentiates a progressive loss of FXN expression in the postmitotic cells that are most severely affected in FRDA. Furthermore, our results showed that silencing of Fe-S cluster biogenesis factors reduced the levels of ELP3, a subunit of the Elongator complex that has roles in growth cone motility and axonal outgrowth. In addition, our studies revealed that silencing of FXN or ISCU induced the α-tubulin acetyltransferase MEC17, resulting in hyperacetylation of α-tubulin. Reversible acetylation of tubulin confers mechanical protection to microtubules51 and controls their interaction with cellular components52 and is critical for neuronal development and function, growth factor or apoptotic signaling, and cell cycle progression. Acetylation of K40 of α-tubulin is mainly controlled by the cytosolic acetyltransferase MEC17 and the cytosolic deacetylases HDAC6 and SIRT2. Notably, a mouse model of FRDA cardiomyopathy with ablation of FXN had increased mitochondrial protein acetylation that was attributed to a decrease in the mitochondrial NAD+/NADH ratio, which can lower the activity of the mitochondrial deacetylase SIRT3. Thus, our findings suggest that the roles of PDHc, ELP3, and MEC17 in the etiology of FRDA, GLRX5-related sideroblastic anemias, and other Fe-S cluster biogenesis disorders warrant further study.
hese results reveal new regulatory pathways and novel roles of the Fe-S cluster biogenesis machinery in modifying the epigenome and acetylome and provide new insights into the etiology of Fe-S cluster biogenesis disorders.
Interestingly, we showed that silencing of FXN and ISCU resulted in increased MEC17 levels and increased α-tubulin acetylation.
Extensive chromatin immunoprecipitation data collected at the FRDA locus, which contains an expanded trinucleotide repeat (GAA)n in the first intron of FXN, had shown that the levels of the heterochromatin mark H3K9me3 were enriched, whereas the levels of acetylated H3 and H4 were reduced. Our finding that decreased Fe-S cluster biogenesis resulted in decreased overall histone acetylation and increased H3K9me3 levels poses an interesting possibility of a negative feedback mechanism that potentiates a progressive loss of FXN expression in the postmitotic cells that are most severely affected in FRDA. Furthermore, our results showed that silencing of Fe-S cluster biogenesis factors reduced the levels of ELP3, a subunit of the Elongator complex that has roles in growth cone motility and axonal outgrowth. In addition, our studies revealed that silencing of FXN or ISCU induced the α-tubulin acetyltransferase MEC17, resulting in hyperacetylation of α-tubulin. Reversible acetylation of tubulin confers mechanical protection to microtubules51 and controls their interaction with cellular components52 and is critical for neuronal development and function, growth factor or apoptotic signaling, and cell cycle progression. Acetylation of K40 of α-tubulin is mainly controlled by the cytosolic acetyltransferase MEC17 and the cytosolic deacetylases HDAC6 and SIRT2. Notably, a mouse model of FRDA cardiomyopathy with ablation of FXN had increased mitochondrial protein acetylation that was attributed to a decrease in the mitochondrial NAD+/NADH ratio, which can lower the activity of the mitochondrial deacetylase SIRT3. Thus, our findings suggest that the roles of PDHc, ELP3, and MEC17 in the etiology of FRDA, GLRX5-related sideroblastic anemias, and other Fe-S cluster biogenesis disorders warrant further study.
Saturday, May 26, 2018
Peripheral blood gene expression reveals an inflammatory transcriptomic signature in Friedreich’s ataxia patients
Daniel Nachun, Fuying Gao, Charles Isaacs, Cassandra Strawser, Zhongan Yang, Deepika Dokuru, Victoria Van Berlo, Renee Sears, Jennifer Farmer, Susan Perlman, David R Lynch, Giovanni Coppola; Human Molecular Genetics, ddy198, doi:10.1093/hmg/ddy198
We identified a transcriptional signature strongly enriched for an inflammatory innate immune response. Future studies should seek to further characterize the role of peripheral inflammation in FRDA pathology and determine its relevance to overall disease progression.
We identified a transcriptional signature strongly enriched for an inflammatory innate immune response. Future studies should seek to further characterize the role of peripheral inflammation in FRDA pathology and determine its relevance to overall disease progression.
A missed Fe-S cluster handoff causes a metabolic shakeup
Olivier Berteau; The Journal of Biological Chemistry 293, 8312-8313. doi: 10.1074/jbc.H118.002883
these findings hold significance for the biochemical and medical communities because the cellular phenotype induced mirrors pathological conditions encountered, for example, in nonadipose tissues such as heart and liver with possible connections to Friedreich's ataxia, nonalcoholic fatty liver disease, and nonalcoholic steatohepatitis. Further research at the intersection between Fe-S cluster biogenesis and cellular metabolism is thus more than likely to bring unexpected insights into the pathogenesis of poorly understood diseases.
these findings hold significance for the biochemical and medical communities because the cellular phenotype induced mirrors pathological conditions encountered, for example, in nonadipose tissues such as heart and liver with possible connections to Friedreich's ataxia, nonalcoholic fatty liver disease, and nonalcoholic steatohepatitis. Further research at the intersection between Fe-S cluster biogenesis and cellular metabolism is thus more than likely to bring unexpected insights into the pathogenesis of poorly understood diseases.
Acute loss of iron–sulfur clusters results in metabolic reprogramming and generation of lipid droplets in mammalian cells
Daniel R. Crooks, Nunziata Maio§, Andrew N. Lane, Michal Jarnik, Richard M. Higashi, Ronald G. Haller, Ye Yang, Teresa W-M. Fan, W. Marston Linehan and Tracey A. Rouault; The Journal of Biological Chemistry 293, 8297-8311. doi: 10.1074/jbc.RA118.001885
Elucidation of the mechanisms of citrate and lipid droplet accumulation in nonadipose tissues during disease states may reveal important insights into the pathogenesis of a significant number of poorly understood diseases.
Elucidation of the mechanisms of citrate and lipid droplet accumulation in nonadipose tissues during disease states may reveal important insights into the pathogenesis of a significant number of poorly understood diseases.
Friday, May 25, 2018
Improving the analysis of composite endpoints in rare disease trials
Martina McMenami, Anna Berglind and James M. S. Wason; Orphanet Journal of Rare Diseases 201813:81 doi:10.1186/s13023-018-0819-1
In rare diseases where there are few or no available treatments and limited opportunity to test emerging new treatments, the power to detect an effective treatment is of critical importance. The augmented binary method with small sample adjustments offers a substantial improvement for trials in these populations over methods currently being used, which throw away valuable information. We recommend the use of the augmented binary method in relevant rare disease trials using composite endpoints and supply R code to assist with the implementation.
In rare diseases where there are few or no available treatments and limited opportunity to test emerging new treatments, the power to detect an effective treatment is of critical importance. The augmented binary method with small sample adjustments offers a substantial improvement for trials in these populations over methods currently being used, which throw away valuable information. We recommend the use of the augmented binary method in relevant rare disease trials using composite endpoints and supply R code to assist with the implementation.
Biomimetic Artificial Epigenetic Code for Targeted Acetylation of Histones
Junichi Taniguchi, Yihong Feng, Ganesh N. Pandian, Fumitaka Hashiya, Takuya Hidaka, Kaori Hashiya, Soyoung Park, Toshikazu Bando, Shinji Ito, and Hiroshi Sugiyama; . Am. Chem. Soc., Article ASAP DOI: 10.1021/jacs.8b01518 Publication Date (Web): May 24, 2018
Recently, Ansari’s group reported a conjugate called Syn-TEF by coupling a PIP with another bromodomain inhibitor(+)-JQ1, selective to the bromodomain and extraterminal(BET) protein family. 45 Syn-TEF1 targeting expanded GAA repeats in the frataxin (FXN) gene successfully recruited BET protein BRD4 (bromodomain 4) to the gene locus in Friedreich’s ataxia (FRDA) patient-derived cells, resulting intranscriptional elongation of FXN. However, Syn-TEF and Bi-PIP target different members of the BD protein family and, therefore, are demonstrated to cause different outcomes; i.e.,while Syn-TEF causes BRD4-dependent transcriptional elongation, Bi-PIP causes P300 dependent histone acetylation. Thus,Bi-PIP and Syn-TEF can be used for different purposes, and this allows us to expand the range of potential applications of the synthetic epigenetic regulators.
Recently, Ansari’s group reported a conjugate called Syn-TEF by coupling a PIP with another bromodomain inhibitor(+)-JQ1, selective to the bromodomain and extraterminal(BET) protein family. 45 Syn-TEF1 targeting expanded GAA repeats in the frataxin (FXN) gene successfully recruited BET protein BRD4 (bromodomain 4) to the gene locus in Friedreich’s ataxia (FRDA) patient-derived cells, resulting intranscriptional elongation of FXN. However, Syn-TEF and Bi-PIP target different members of the BD protein family and, therefore, are demonstrated to cause different outcomes; i.e.,while Syn-TEF causes BRD4-dependent transcriptional elongation, Bi-PIP causes P300 dependent histone acetylation. Thus,Bi-PIP and Syn-TEF can be used for different purposes, and this allows us to expand the range of potential applications of the synthetic epigenetic regulators.
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