Publications by authors named "Malvin Jefri"

7 Publications

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Lesch-Nyhan disease causes impaired energy metabolism and reduced developmental potential in midbrain dopaminergic cells.

Stem Cell Reports 2021 Jul 1;16(7):1749-1762. Epub 2021 Jul 1.

Psychiatric Genetics Group, McGill University, Montreal, QC, Canada; Department of Psychiatry, McGill University and Douglas Hospital Research Institute, 6875 LaSalle Boulevard, Frank Common Building, Room 2101.2, Montreal, QC H4H 1R3, Canada. Electronic address:

Mutations in HPRT1, a gene encoding a rate-limiting enzyme for purine salvage, cause Lesch-Nyhan disease which is characterized by self-injury and motor impairments. We leveraged stem cell and genetic engineering technologies to model the disease in isogenic and patient-derived forebrain and midbrain cell types. Dopaminergic progenitor cells deficient in HPRT showed decreased intensity of all developmental cell-fate markers measured. Metabolic analyses revealed significant loss of all purine derivatives, except hypoxanthine, and impaired glycolysis and oxidative phosphorylation. real-time glucose tracing demonstrated increased shunting to the pentose phosphate pathway for de novo purine synthesis at the expense of ATP production. Purine depletion in dopaminergic progenitor cells resulted in loss of RHEB, impairing mTORC1 activation. These data demonstrate dopaminergic-specific effects of purine salvage deficiency and unexpectedly reveal that dopaminergic progenitor cells are programmed to a high-energy state prior to higher energy demands of terminally differentiated cells.
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http://dx.doi.org/10.1016/j.stemcr.2021.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8282463PMC
July 2021

Stimulation of L-type calcium channels increases tyrosine hydroxylase and dopamine in ventral midbrain cells induced from somatic cells.

Stem Cells Transl Med 2020 Jun 10;9(6):697-712. Epub 2020 Mar 10.

Psychiatric Genetics Group, McGill University, Montreal, Quebec, Canada.

Making high-quality dopamine (DA)-producing cells for basic biological or small molecule screening studies is critical for the development of novel therapeutics for disorders of the ventral midbrain. Currently, many ventral midbrain assays have low signal-to-noise ratio due to low levels of cellular DA and the rate-limiting enzyme of DA synthesis, tyrosine hydroxylase (TH), hampering discovery efforts. Using intensively characterized ventral midbrain cells derived from human skin, which demonstrate calcium pacemaking activity and classical electrophysiological properties, we show that an L-type calcium agonist can significantly increase TH protein levels and DA content and release. Live calcium imaging suggests that it is the immediate influx of calcium occurring simultaneously in all cells that drives this effect. Genome-wide expression profiling suggests that L-type calcium channel stimulation has a significant effect on specific genes related to DA synthesis and affects expression of L-type calcium receptor subunits from the CACNA1 and CACNA2D families. Together, our findings provide an advance in the ability to increase DA and TH levels to improve the accuracy of disease modeling and small molecule screening for disorders of the ventral midbrain, including Parkinson's disease.
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http://dx.doi.org/10.1002/sctm.18-0180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7214648PMC
June 2020

Mutations in ACTL6B Cause Neurodevelopmental Deficits and Epilepsy and Lead to Loss of Dendrites in Human Neurons.

Am J Hum Genet 2019 05 25;104(5):815-834. Epub 2019 Apr 25.

Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, WC1N 3BG London, UK.

We identified individuals with variations in ACTL6B, a component of the chromatin remodeling machinery including the BAF complex. Ten individuals harbored bi-allelic mutations and presented with global developmental delay, epileptic encephalopathy, and spasticity, and ten individuals with de novo heterozygous mutations displayed intellectual disability, ambulation deficits, severe language impairment, hypotonia, Rett-like stereotypies, and minor facial dysmorphisms (wide mouth, diastema, bulbous nose). Nine of these ten unrelated individuals had the identical de novo c.1027G>A (p.Gly343Arg) mutation. Human-derived neurons were generated that recaptured ACTL6B expression patterns in development from progenitor cell to post-mitotic neuron, validating the use of this model. Engineered knock-out of ACTL6B in wild-type human neurons resulted in profound deficits in dendrite development, a result recapitulated in two individuals with different bi-allelic mutations, and reversed on clonal genetic repair or exogenous expression of ACTL6B. Whole-transcriptome analyses and whole-genomic profiling of the BAF complex in wild-type and bi-allelic mutant ACTL6B neural progenitor cells and neurons revealed increased genomic binding of the BAF complex in ACTL6B mutants, with corresponding transcriptional changes in several genes including TPPP and FSCN1, suggesting that altered regulation of some cytoskeletal genes contribute to altered dendrite development. Assessment of bi-alleic and heterozygous ACTL6B mutations on an ACTL6B knock-out human background demonstrated that bi-allelic mutations mimic engineered deletion deficits while heterozygous mutations do not, suggesting that the former are loss of function and the latter are gain of function. These results reveal a role for ACTL6B in neurodevelopment and implicate another component of chromatin remodeling machinery in brain disease.
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http://dx.doi.org/10.1016/j.ajhg.2019.03.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6507050PMC
May 2019

Differentiation of Human Induced Pluripotent Stem Cells (iPSCs) into an Effective Model of Forebrain Neural Progenitor Cells and Mature Neurons.

Bio Protoc 2019 Mar 5;9(5):e3188. Epub 2019 Mar 5.

Psychiatric Genetics Group, McGill University and Douglas Hospital Research Institute, Department of Psychiatry, Verdun, Montreal, QC H4H 1R3, Canada.

Induced Pluripotent Stem Cells (iPSCs) are pluripotent stem cells that can be generated from somatic cells, and provide a way to model the development of neural tissues . One particularly interesting application of iPSCs is the development of neurons analogous to those found in the human forebrain. Forebrain neurons play a central role in cognition and sensory processing, and deficits in forebrain neuronal activity contributes to a host of conditions, including epilepsy, Alzheimer's disease, and schizophrenia. Here, we present our protocol for differentiating iPSCs into forebrain neural progenitor cells (NPCs) and neurons, whereby neural rosettes are generated from stem cells without dissociation and NPCs purified from rosettes based on their adhesion, resulting in a more rapid generation of pure NPC cultures. Neural progenitor cells can be maintained as long-term cultures, or differentiated into forebrain neurons. This protocol provides a simplified and fast methodology of generating forebrain NPCs and neurons, and enables researchers to generate effective models to study forebrain disease and neurodevelopment. This protocol can also be easily adapted to generate other neural lineages.
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http://dx.doi.org/10.21769/BioProtoc.3188DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7854068PMC
March 2019

Disruption of GRIN2B Impairs Differentiation in Human Neurons.

Stem Cell Reports 2018 07 21;11(1):183-196. Epub 2018 Jun 21.

McGill University and Douglas Hospital Research Institute, Department of Psychiatry, 6875 LaSalle Boulevard, Frank Common Building, Room 2101.2, Verdun, Montreal, QC H4H 1R3, Canada. Electronic address:

Heterozygous loss-of-function mutations in GRIN2B, a subunit of the NMDA receptor, cause intellectual disability and language impairment. We developed clonal models of GRIN2B deletion and loss-of-function mutations in a region coding for the glutamate binding domain in human cells and generated neurons from a patient harboring a missense mutation in the same domain. Transcriptome analysis revealed extensive increases in genes associated with cell proliferation and decreases in genes associated with neuron differentiation, a result supported by extensive protein analyses. Using electrophysiology and calcium imaging, we demonstrate that NMDA receptors are present on neural progenitor cells and that human mutations in GRIN2B can impair calcium influx and membrane depolarization even in a presumed undifferentiated cell state, highlighting an important role for non-synaptic NMDA receptors. It may be this function, in part, which underlies the neurological disease observed in patients with GRIN2B mutations.
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http://dx.doi.org/10.1016/j.stemcr.2018.05.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6067152PMC
July 2018

Strategies to Advance Drug Discovery in Rare Monogenic Intellectual Disability Syndromes.

Int J Neuropsychopharmacol 2018 03;21(3):201-206

Department of Human Genetics, McGill University, Montreal, QC, Canada.

Some intellectual disability syndromes are caused by a mutation in a single gene and have been the focus of therapeutic intervention attempts, such as Fragile X and Rett Syndrome, albeit with limited success. The rate at which new drugs are discovered and tested in humans for intellectual disability is progressing at a relatively slow pace. This is particularly true for rare diseases where so few patients make high-quality clinical trials challenging. We discuss how new advances in human stem cell reprogramming and gene editing can facilitate preclinical study design and we propose new workflows for how the preclinical to clinical trajectory might proceed given the small number of subjects available in rare monogenic intellectual disability syndromes.
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http://dx.doi.org/10.1093/ijnp/pyx090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5836272PMC
March 2018

YKL-40 regulated epithelial-mesenchymal transition and migration/invasion enhancement in non-small cell lung cancer.

BMC Cancer 2015 Aug 15;15:590. Epub 2015 Aug 15.

Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, 1001 University Road, Hsinchu, Taiwan, 300, ROC.

Background: YKL-40 is a secreted inflammatory protein that its overexpression has been reported to correlate with poor outcome of various malignant diseases, especially in cancer. However, the function of this protein is still unclear.

Methods: The clinical prognosis of non-small cell lung cancers (NSCLC) patients and their clinical YKL-40 expressions were obtained from the Prognoscan database. The expressions of YKL-40 in patient samples were determined by Western Blotting assay. YKL-40 gene knockdown and overexpression were performed on NSCLC cancer cells (CL1-1 and CL1-5). The cells were investigated for their epithelial-mesenchymal transition (EMT) markers gene modulation through Western Blotting and RT-PCR. Further cell metastatic abilities were assessed by transwell migration and invasion assay.

Result: In this study, YKL-40 was observed to be highly expressed in NSCLC specimens. Furthermore, determined by the PrognoScan database analysis, patients with high expression levels of YKL-40 were found with poor prognosis. In the in vitro study, different characteristics of NSCLC cell lines (CL1-1, H23, H838, CL1-5, and H2009) were used as study models, where YKL-40 expression levels were determined to correlate with the phenotypic characteristics of cancer metastasis. In this study,YKL-40 was demonstrated to regulate EMT marker expressions such as Twist, Snail, Slug, N-cadherin, Vimentin, and E-cadherin. The protein's affects in cancer cell migration and invasion were also observed in YKL-40 overexpression or knock down NSCLC cell lines.

Conclusion: All of results from this study suggest that YKL-40 is a major factor in NSCLC metastasis. Thus, YKL-40 may serve as therapeutic targets for NSCLC patients in the future.
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http://dx.doi.org/10.1186/s12885-015-1592-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537570PMC
August 2015
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