PubMed

Recent Publications

Interrogation of kinase genetic interactions provides a global view of PAK1-mediated signal transduction pathways.

Interrogation of kinase genetic interactions provides a global view of PAK1-mediated signal transduction pathways.

J Biol Chem. 2020 Oct 15;:

Authors: Kim JH, Seo Y, Jo M, Jeon H, Kim YS, Kim EJ, Seo D, Lee WH, Kim SR, Yachie N, Zhong Q, Vidal M, Roth FP, Suk K

Abstract
Kinases are critical components of intracellular signaling pathways and have been extensively investigated in regards to their roles in cancer. p21-activated kinase-1 (PAK1) is a serine/threonine kinase that has been previously implicated in numerous biological processes, such as cell migration, cell cycle progression, cell motility, invasion, and angiogenesis, in glioma and other cancers. However, the signaling network linked to PAK1 is not fully defined. We previously reported a large-scale yeast genetic interaction screen using toxicity as a readout to identify candidate PAK1 genetic interactions. En masse transformation of the PAK1 gene into 4,653 homozygous diploid S. cerevisiae yeast deletion mutants identified approximately 400 candidates that suppressed yeast toxicity. Here we selected 19 candidate PAK1 genetic interactions that had human orthologs and were expressed in glioma for further examination in mammalian cells, brain slice cultures, and orthotopic glioma models. RNAi and pharmacological inhibition of potential PAK1 interactors confirmed that DPP4, KIF11, mTOR, PKM2, SGPP1, TTK, and YWHAE regulate PAK1-induced cell migration, and revealed the importance of genes related to the mitotic spindle, proteolysis, autophagy, and metabolism in PAK1-mediated glioma cell migration, drug resistance, and proliferation. AKT1 was further identified as a downstream mediator of the PAK1-TTK genetic interaction. Taken together, these data provide a global view of PAK1-mediated signal transduction pathways and point to potential new drug targets for glioma therapy.

PMID: 33060198 [PubMed - as supplied by publisher]



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An Injectable Hyaluronan-Methylcellulose (HAMC) Hydrogel Combined with Wharton's Jelly-Derived Mesenchymal Stromal Cells (WJ-MSCs) Promotes Degenerative Disc Repair.

An Injectable Hyaluronan-Methylcellulose (HAMC) Hydrogel Combined with Wharton's Jelly-Derived Mesenchymal Stromal Cells (WJ-MSCs) Promotes Degenerative Disc Repair.

Int J Mol Sci. 2020 Oct 07;21(19):

Authors: Choi UY, Joshi HP, Payne S, Kim KT, Kyung JW, Choi H, Cooke MJ, Kwon SY, Roh EJ, Sohn S, Shoichet MS, Han I

Abstract
Intervertebral disc (IVD) degeneration is one of the predominant causes of chronic low back pain (LBP), which is a leading cause of disability worldwide. Despite substantial progress in cell therapy for the treatment of IVD degeneration, significant challenges remain for clinical application. Here, we investigated the effectiveness of hyaluronan-methylcellulose (HAMC) hydrogels loaded with Wharton's Jelly-derived mesenchymal stromal cell (WJ-MSCs) in vitro and in a rat coccygeal IVD degeneration model. Following induction of injury-induced IVD degeneration, female Sprague-Dawley rats were randomized into four groups to undergo a single intradiscal injection of the following: (1) phosphate buffered saline (PBS) vehicle, (2) HAMC, (3) WJ-MSCs (2 × 104 cells), and (4) WJ-MSCs-loaded HAMC (WJ-MSCs/HAMC) (n = 10/each group). Coccygeal discs were removed following sacrifice 6 weeks after implantation for radiologic and histologic analysis. We confirmed previous findings that encapsulation in HAMC increases the viability of WJ-MSCs for disc repair. The HAMC gel maintained significant cell viability in vitro. In addition, combined implantation of WJ-MSCs and HAMC significantly promoted degenerative disc repair compared to WJ-MSCs alone, presumably by improving nucleus pulposus cells viability and decreasing extracellular matrix degradation. Our results suggest that WJ-MSCs-loaded HAMC promotes IVD repair more effectively than cell injection alone and supports the potential clinical use of HAMC for cell delivery to arrest IVD degeneration or to promote IVD regeneration.

PMID: 33036383 [PubMed - as supplied by publisher]



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DNA-Controlled Encapsulation of Small Molecules in Protein Nanoparticles.

DNA-Controlled Encapsulation of Small Molecules in Protein Nanoparticles.

J Am Chem Soc. 2020 Oct 06;:

Authors: Ngo W, Stordy B, Lazarovits J, Raja EK, Etienne CL, Chan WCW

Abstract
A nanoparticle can hold multiple types of therapeutic and imaging agents for disease treatment and diagnosis. However, controlling the storage of molecules in nanoparticles is challenging, because nonspecific intermolecular interactions are used for encapsulation. Here, we used specific DNA interactions to store molecules in nanoparticles. We made nanoparticles containing DNA anchors to capture DNA-conjugated small molecules. By changing the sequences and stoichiometry of DNA anchors, we can control the amount and ratio of molecules with different chemical properties in the nanoparticles. We modified the cytotoxicity of our nanoparticles to cancer cells by changing the ratio of encapsulated drugs (mertansine and doxorubicin). Specifically controlling the storage of multiple types of molecules allows us to optimize the properties of combination drug and imaging nanoparticles.

PMID: 33022172 [PubMed - as supplied by publisher]



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An efficient KRAB domain for CRISPRi applications in human cells.

An efficient KRAB domain for CRISPRi applications in human cells.

Nat Methods. 2020 Oct 05;:

Authors: Alerasool N, Segal D, Lee H, Taipale M

Abstract
Clustered regularly interspaced short palindromic repeat interference (CRISPRi), based on the fusion of inactive Cas9 (dCas9) to the Krüppel-associated box (KRAB) repressor, is a powerful platform for silencing gene expression. However, it suffers from incomplete silencing of target genes. We assayed 57 KRAB domains for their repressive potency and identified the ZIM3 KRAB domain as an exceptionally potent repressor. We establish that ZIM3 KRAB-dCas9 fusion silences gene expression more efficiently than existing platforms.

PMID: 33020655 [PubMed - as supplied by publisher]



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Constraint-induced movement therapy promotes motor recovery after neonatal stroke in the absence of neural precursor activation.

Constraint-induced movement therapy promotes motor recovery after neonatal stroke in the absence of neural precursor activation.

Eur J Neurosci. 2020 Oct 03;:

Authors: Adams KV, Mahmud N, Green-Holland M, Vonderwalde I, Umebayashi D, Sachewsky N, Coles BL, van der Kooy D, Morshead CM

Abstract
Neonatal stroke is a leading cause of long-term disability and currently available rehabilitation treatments are insufficient to promote recovery. Activating neural precursor cells (NPCs) in adult rodents, in combination with rehabilitation, can accelerate functional recovery following stroke. Here, we describe a novel method of constraint-induced movement therapy (CIMT) in a rodent model of neonatal stroke that leads to improved functional outcomes, and asked whether the recovery was correlated with expansion of NPCs. A hypoxia/ischemia (H/I) injury was induced on postnatal day 8 (PND8) via unilateral carotid artery ligation followed by systemic hypoxia. One week and two weeks post-H/I, CIMT was administered in the form of 3 botulinum toxin (Botox) injections, which induced temporary paralysis in the unaffected limb. Functional recovery was assessed using the foot fault task. NPC proliferation was assessed using the neurosphere assay and EdU immunohistochemistry. We found that neonatal H/I injury alone expands the NPC pool by >2.5 fold relative to controls. We determined that Botox injections as a means to provide CIMT results in significant functional motor recovery following H/I. However, CIMT does not lead to enhanced NPC activation or migration into the injured parenchyma in vivo. At the time of functional recovery increased numbers of proliferating inflammatory cells were found within the injured motor cortex. Together, these findings suggest that NPC activation following CIMT does not account for the observed functional improvement and suggests that CIMT-mediated modification of the CNS inflammatory response may play a role in the motor recovery.

PMID: 33010080 [PubMed - as supplied by publisher]



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Fast and Flexible Protein Design Using Deep Graph Neural Networks.

Related Articles

Fast and Flexible Protein Design Using Deep Graph Neural Networks.

Cell Syst. 2020 Sep 15;:

Authors: Strokach A, Becerra D, Corbi-Verge C, Perez-Riba A, Kim PM

Abstract
Protein structure and function is determined by the arrangement of the linear sequence of amino acids in 3D space. We show that a deep graph neural network, ProteinSolver, can precisely design sequences that fold into a predetermined shape by phrasing this challenge as a constraint satisfaction problem (CSP), akin to Sudoku puzzles. We trained ProteinSolver on over 70,000,000 real protein sequences corresponding to over 80,000 structures. We show that our method rapidly designs new protein sequences and benchmark them in silico using energy-based scores, molecular dynamics, and structure prediction methods. As a proof-of-principle validation, we use ProteinSolver to generate sequences that match the structure of serum albumin, then synthesize the top-scoring design and validate it in vitro using circular dichroism. ProteinSolver is freely available at http://design.proteinsolver.org and https://gitlab.com/ostrokach/proteinsolver. A record of this paper's transparent peer review process is included in the Supplemental Information.

PMID: 32971019 [PubMed - as supplied by publisher]



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Parental Bias Has Benefits.

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Parental Bias Has Benefits.

Neuron. 2020 09 23;107(6):994-996

Authors: DeVeale B, van der Kooy D

Abstract
In this issue, Laukoter et al., 2020 report that parent-of-origin-dependent expression is homogeneous across distinct cortical cell types and within individual populations. Conversely, they observe preferential sensitivity of astrocytes to altered doses of imprinted loci.

PMID: 32971001 [PubMed - indexed for MEDLINE]



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Functional genomic landscape of cancer-intrinsic evasion of killing by T cells.

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Functional genomic landscape of cancer-intrinsic evasion of killing by T cells.

Nature. 2020 10;586(7827):120-126

Authors: Lawson KA, Sousa CM, Zhang X, Kim E, Akthar R, Caumanns JJ, Yao Y, Mikolajewicz N, Ross C, Brown KR, Zid AA, Fan ZP, Hui S, Krall JA, Simons DM, Slater CJ, De Jesus V, Tang L, Singh R, Goldford JE, Martin S, Huang Q, Francis EA, Habsid A, Climie R, Tieu D, Wei J, Li R, Tong AHY, Aregger M, Chan KS, Han H, Wang X, Mero P, Brumell JH, Finelli A, Ailles L, Bader G, Smolen GA, Kingsbury GA, Hart T, Kung C, Moffat J

Abstract
The genetic circuits that allow cancer cells to evade destruction by the host immune system remain poorly understood1-3. Here, to identify a phenotypically robust core set of genes and pathways that enable cancer cells to evade killing mediated by cytotoxic T lymphocytes (CTLs), we performed genome-wide CRISPR screens across a panel of genetically diverse mouse cancer cell lines that were cultured in the presence of CTLs. We identify a core set of 182 genes across these mouse cancer models, the individual perturbation of which increases either the sensitivity or the resistance of cancer cells to CTL-mediated toxicity. Systematic exploration of our dataset using genetic co-similarity reveals the hierarchical and coordinated manner in which genes and pathways act in cancer cells to orchestrate their evasion of CTLs, and shows that discrete functional modules that control the interferon response and tumour necrosis factor (TNF)-induced cytotoxicity are dominant sub-phenotypes. Our data establish a central role for genes that were previously identified as negative regulators of the type-II interferon response (for example, Ptpn2, Socs1 and Adar1) in mediating CTL evasion, and show that the lipid-droplet-related gene Fitm2 is required for maintaining cell fitness after exposure to interferon-γ (IFNγ). In addition, we identify the autophagy pathway as a conserved mediator of the evasion of CTLs by cancer cells, and show that this pathway is required to resist cytotoxicity induced by the cytokines IFNγ and TNF. Through the mapping of cytokine- and CTL-based genetic interactions, together with in vivo CRISPR screens, we show how the pleiotropic effects of autophagy control cancer-cell-intrinsic evasion of killing by CTLs and we highlight the importance of these effects within the tumour microenvironment. Collectively, these data expand our knowledge of the genetic circuits that are involved in the evasion of the immune system by cancer cells, and highlight genetic interactions that contribute to phenotypes associated with escape from killing by CTLs.

PMID: 32968282 [PubMed - indexed for MEDLINE]



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Systematic analysis of bypass suppression of essential genes.

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Systematic analysis of bypass suppression of essential genes.

Mol Syst Biol. 2020 Sep;16(9):e9828

Authors: van Leeuwen J, Pons C, Tan G, Wang JZ, Hou J, Weile J, Gebbia M, Liang W, Shuteriqi E, Li Z, Lopes M, Ušaj M, Dos Santos Lopes A, van Lieshout N, Myers CL, Roth FP, Aloy P, Andrews BJ, Boone C

Abstract
Essential genes tend to be highly conserved across eukaryotes, but, in some cases, their critical roles can be bypassed through genetic rewiring. From a systematic analysis of 728 different essential yeast genes, we discovered that 124 (17%) were dispensable essential genes. Through whole-genome sequencing and detailed genetic analysis, we investigated the genetic interactions and genome alterations underlying bypass suppression. Dispensable essential genes often had paralogs, were enriched for genes encoding membrane-associated proteins, and were depleted for members of protein complexes. Functionally related genes frequently drove the bypass suppression interactions. These gene properties were predictive of essential gene dispensability and of specific suppressors among hundreds of genes on aneuploid chromosomes. Our findings identify yeast's core essential gene set and reveal that the properties of dispensable essential genes are conserved from yeast to human cells, correlating with human genes that display cell line-specific essentiality in the Cancer Dependency Map (DepMap) project.

PMID: 32939983 [PubMed - in process]



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Reengineering biocatalysts: Computational redesign of chondroitinase ABC improves efficacy and stability.

Reengineering biocatalysts: Computational redesign of chondroitinase ABC improves efficacy and stability.

Sci Adv. 2020 Aug;6(34):

Authors: Hettiaratchi MH, O'Meara MJ, O'Meara TR, Pickering AJ, Letko-Khait N, Shoichet MS

Abstract
Maintaining biocatalyst stability and activity is a critical challenge. Chondroitinase ABC (ChABC) has shown promise in central nervous system (CNS) regeneration, yet its therapeutic utility is severely limited by instability. We computationally reengineered ChABC by introducing 37, 55, and 92 amino acid changes using consensus design and forcefield-based optimization. All mutants were more stable than wild-type ChABC with increased aggregation temperatures between 4° and 8°C. Only ChABC with 37 mutations (ChABC-37) was more active and had a 6.5 times greater half-life than wild-type ChABC, increasing to 106 hours (4.4 days) from only 16.8 hours. ChABC-37, expressed as a fusion protein with Src homology 3 (ChABC-37-SH3), was active for 7 days when released from a hydrogel modified with SH3-binding peptides. This study demonstrates the broad opportunity to improve biocatalysts through computational engineering and sets the stage for future testing of this substantially improved protein in the treatment of debilitating CNS injuries.

PMID: 32937356 [PubMed - as supplied by publisher]



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