scholarly journals Breaking Boundaries in the Brain—Advances in Editing Tools for Neurogenetic Disorders

2021 ◽  
Vol 3 ◽  
Author(s):  
Bronte A. Coorey ◽  
Wendy A. Gold
Keyword(s):  
Gene Transfer ◽  
Neurological Disorders ◽  
Gene Editing ◽  
De Novo ◽  
Nervous System Development ◽  
Dominant Negative ◽  
Regulatory Control ◽  
Target Cells ◽  
Coding Region ◽  
Neurogenetic Disorders

Monogenic neurological disorders are devastating, affecting hundreds of millions of people globally and present a substantial burden to individuals, carers, and healthcare systems. These disorders are predominantly caused by inherited or de novo variants that result in impairments to nervous system development, neurodegeneration, or impaired neuronal function. No cure exists for these disorders with many being refractory to medication. However, since monogenic neurological disorders have a single causal factor, they are also excellent targets for innovative, therapies such as gene therapy. Despite this promise, gene transfer therapies are limited in that they are only suitable for neurogenetic disorders that fit within the technological reach of these therapies. The limitations include the size of the coding region of the gene, the regulatory control of expression (dosage sensitivity), the mode of expression (e.g., dominant negative) and access to target cells. Gene editing therapies are an alternative strategy to gene transfer therapy as they have the potential of overcoming some of these hurdles, enabling the retention of physiological expression of the gene and offers precision medicine-based therapies where individual variants can be repaired. This review focusses on the existing gene editing technologies for neurogenetic disorders and how these propose to overcome the challenges common to neurogenetic disorders with gene transfer therapies as well as their own challenges.

scholarly journals A Novel Intronic Pathogenic Variant in STAR With a Dominant Negative Mechanism Causes Attenuated Lipoid Congenital Adrenal Hyperplasia

2021 ◽  
Vol 9 ◽  
pp. 232470962110146
Author(s):  
Erin Finn ◽  
Kimberly Kripps ◽  
Christina Chambers ◽  
Michele Rapp ◽  
Naomi J. L. Meeks ◽  
...  
Keyword(s):  
Congenital Adrenal Hyperplasia ◽  
Autosomal Recessive ◽  
De Novo ◽  
Dominant Negative ◽  
Adrenal Hyperplasia ◽  
Primary Adrenal Insufficiency ◽  
Heterozygous Variant ◽  
Novel Variant ◽  
Autosomal Recessive Condition ◽  
Clinically Significant

Lipoid congenital adrenal hyperplasia (LCAH) is typically inherited as an autosomal recessive condition. There are 3 reports of individuals with a dominantly acting heterozygous variant leading to a clinically significant phenotype. We report a 46,XY child with a novel heterozygous intronic variant in STAR resulting in LCAH with an attenuated genital phenotype. The patient presented with neonatal hypoglycemia and had descended testes with a fused scrotum and small phallus. Evaluation revealed primary adrenal insufficiency with deficiencies of cortisol, aldosterone, and androgens. He was found to have a de novo heterozygous novel variant in STAR: c.65-2A>C. We report a case of a novel variant and review of other dominant mutations at the same position in the literature. Clinicians should be aware of the possibility of attenuated genital phenotypes of LCAH and the contribution of de novo variants in STAR at c.65-2 to the pathogenesis of that phenotype.

scholarly journals Neurotrophins as Key Regulators of Cell Metabolism: Implications for Cholesterol Homeostasis

2021 ◽  
Vol 22 (11) ◽  
pp. 5692
Author(s):  
Mayra Colardo ◽  
Noemi Martella ◽  
Daniele Pensabene ◽  
Silvia Siteni ◽  
Sabrina Di Bartolomeo ◽  
...  
Keyword(s):  
Growth Factors ◽  
Cholesterol Metabolism ◽  
System Development ◽  
Cell Metabolism ◽  
Redox Balance ◽  
Nervous System Development ◽  
Cholesterol Homeostasis ◽  
Signaling Cascades ◽  
Target Cells ◽  
The Impact

Neurotrophins constitute a family of growth factors initially characterized as predominant mediators of nervous system development, neuronal survival, regeneration and plasticity. Their biological activity is promoted by the binding of two different types of receptors, leading to the generation of multiple and variegated signaling cascades in the target cells. Increasing evidence indicates that neurotrophins are also emerging as crucial regulators of metabolic processes in both neuronal and non-neuronal cells. In this context, it has been reported that neurotrophins affect redox balance, autophagy, glucose homeostasis and energy expenditure. Additionally, the trophic support provided by these secreted factors may involve the regulation of cholesterol metabolism. In this review, we examine the neurotrophins’ signaling pathways and their effects on metabolism by critically discussing the most up-to-date information. In particular, we gather experimental evidence demonstrating the impact of these growth factors on cholesterol metabolism.

Osmotic stress-induced remodeling of the cortical cytoskeleton

2002 ◽  
Vol 283 (3) ◽  
pp. C850-C865 ◽  
Author(s):  
Caterina Di Ciano ◽  
Zilin Nie ◽  
Katalin Szászi ◽  
Alison Lewis ◽  
Takehito Uruno ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
De Novo ◽  
Small Gtpases ◽  
Dominant Negative ◽  
Actin Binding ◽  
Cell Cortex ◽  
Actin Assembly ◽  
Signaling Mechanism ◽  
Actin Binding Domain ◽  
Cytoskeleton Remodeling

Osmotic stress is known to affect the cytoskeleton; however, this adaptive response has remained poorly characterized, and the underlying signaling pathways are unexplored. Here we show that hypertonicity induces submembranous de novo F-actin assembly concomitant with the peripheral translocation and colocalization of cortactin and the actin-related protein 2/3 (Arp2/3) complex, which are key components of the actin nucleation machinery. Additionally, hyperosmolarity promotes the association of cortactin with Arp2/3 as revealed by coimmunoprecipitation. Using various truncation or phosphorylation-incompetent mutants, we show that cortactin translocation requires the Arp2/3- or the F-actin binding domain, but the process is independent of the shrinkage-induced tyrosine phosphorylation of cortactin. Looking for an alternative signaling mechanism, we found that hypertonicity stimulates Rac and Cdc42. This appears to be a key event in the osmotically triggered cytoskeletal reorganization, because 1) constitutively active small GTPases translocate cortactin, 2) Rac and cortactin colocalize at the periphery of hypertonically challenged cells, and 3) dominant-negative Rac and Cdc42 inhibit the hypertonicity-provoked cortactin and Arp3 translocation. The Rho family-dependent cytoskeleton remodeling may be an important osmoprotective response that reinforces the cell cortex.

scholarly journals Different modes of internalization of apoptotic alkyl-lysophospholipid and cell-rescuing lysophosphatidylcholine

2003 ◽  
Vol 374 (3) ◽  
pp. 747-753 ◽  
Author(s):  
Arnold H. van der LUIT ◽  
Marianne BUDDE ◽  
Marcel VERHEIJ ◽  
Wim J. van BLITTERSWIJK
Keyword(s):  
Lipid Rafts ◽  
De Novo ◽  
Structural Similarity ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Chemotherapeutic Drugs ◽  
Alternative Substrate ◽  
High Structural Similarity ◽  
Additional Cell ◽  
Cell Membrane Level

The synthetic alkyl-lysophospholipid (ALP), Et-18-OCH3 (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine), can induce apoptosis in tumour cells. Unlike conventional chemotherapeutic drugs, ALP acts at the cell-membrane level. We have reported previously that ALP is internalized, and interferes with phosphatidylcholine (PC) biosynthesis de novo, which appeared to be essential for survival in lymphoma cells [Van der Luit, Budde, Ruurs, Verheij and Van Blitterswijk (2002) J. Biol. Chem. 277, 39541–39547]. Here, we report that, in HeLa cells, ALP accumulates in lipid rafts, and that internalization is inhibited by low temperature, monensin, disruption of lipid rafts and expression of a dominant-negative mutant of dynamin bearing a replacement of Lys44 with alanine (K44A). Thus ALP is internalized via raft- and dynamin-mediated endocytosis. Dynamin-K44A alleviated the ALP-induced inhibition of PC synthesis and rescued the cells from apoptosis induction. Additional cell rescue was attained by exogenous lysoPC, which after internalization serves as an alternative substrate for PC synthesis (through acylation). Unlike ALP, and despite the high structural similarity to ALP, lysoPC uptake did not occur via lipid rafts and did not depend on functional dynamin, indicating no involvement of endocytosis. Albumin back-extraction experiments suggested that (radiolabelled) lysoPC undergoes transbilayer movement (flipping). We conclude that ALP is internalized by endocytosis via lipid rafts to cause apoptosis, while exogenous cell-rescuing lysoPC traverses the plasma membrane outside rafts by flipping. Additionally, our data imply the importance of ether bonds in lyso-phospholipids, such as in ALP, for partitioning in lipid rafts.

scholarly journals Distinct Subregions of Swi1 Manifest Striking Differences in Prion Transmission and SWI/SNF Function

2010 ◽  
Vol 30 (19) ◽  
pp. 4644-4655 ◽  
Author(s):  
Zhiqiang Du ◽  
Emily T. Crow ◽  
Hyun Seok Kang ◽  
Liming Li
Keyword(s):  
Chromatin Remodeling ◽  
De Novo ◽  
Amino Acid Residues ◽  
Coding Region ◽  
Conformational Switch ◽  
Amyloid Fibers ◽  
Aggregation Pattern ◽  
Prion Transmission ◽  
Shed Light

ABSTRACT We have recently reported that the yeast chromatin-remodeling factor Swi1 can exist as a prion, [SWI +], demonstrating a link between prionogenesis and global transcriptional regulation. To shed light on how the Swi1 conformational switch influences Swi1 function and to define the sequence and structural requirements for [SWI +] formation and propagation, we functionally dissected the Swi1 molecule. We show here that the [SWI +] prion features are solely attributable to the first 327 amino acid residues (N), a region that is asparagine rich. N was aggregated in [SWI+ ] cells but diffuse in [swi− ] cells; chromosomal deletion of the N-coding region resulted in [SWI +] loss, and recombinant N peptide was able to form infectious amyloid fibers in vitro, enabling [SWI +] de novo formation through a simple transformation. Although the glutamine-rich middle region (Q) was not sufficient to aggregate in [SWI +] cells or essential for SWI/SNF function, it significantly modified the Swi1 aggregation pattern and Swi1 function. We also show that excessive Swi1 incurred Li+/Na+ sensitivity and that the N/Q regions are important for this gain of sensitivity. Taken together, our results provide the final proof of “protein-only” transmission of [SWI +] and demonstrate that the widely distributed “dispensable” glutamine/asparagine-rich regions/motifs might have important and divergent biological functions.

scholarly journals A disease-associated frameshift mutation in caveolin-1 disrupts caveolae formation and function through introduction of a de novo ER retention signal

2017 ◽  
Vol 28 (22) ◽  
pp. 3095-3111 ◽  
Author(s):  
Courtney A. Copeland ◽  
Bing Han ◽  
Ajit Tiwari ◽  
Eric D. Austin ◽  
James E. Loyd ◽  
...  
Keyword(s):  
Frameshift Mutation ◽  
De Novo ◽  
Dominant Negative ◽  
Caveolin 1 ◽  
Protein Levels ◽  
C Terminus ◽  
Er Retention ◽  
And Function ◽  
Er Retention Signal ◽  
Retention Signal

Caveolin-1 (CAV1) is an essential component of caveolae and is implicated in numerous physiological processes. Recent studies have identified heterozygous mutations in the CAV1 gene in patients with pulmonary arterial hypertension (PAH), but the mechanisms by which these mutations impact caveolae assembly and contribute to disease remain unclear. To address this question, we examined the consequences of a familial PAH-associated frameshift mutation in CAV1, P158PfsX22, on caveolae assembly and function. We show that C-terminus of the CAV1 P158 protein contains a functional ER-retention signal that inhibits ER exit and caveolae formation and accelerates CAV1 turnover in Cav1–/– MEFs. Moreover, when coexpressed with wild-type (WT) CAV1 in Cav1–/– MEFs, CAV1-P158 functions as a dominant negative by partially disrupting WT CAV1 trafficking. In patient skin fibroblasts, CAV1 and caveolar accessory protein levels are reduced, fewer caveolae are observed, and CAV1 complexes exhibit biochemical abnormalities. Patient fibroblasts also exhibit decreased resistance to a hypo-osmotic challenge, suggesting the function of caveolae as membrane reservoir is compromised. We conclude that the P158PfsX22 frameshift introduces a gain of function that gives rise to a dominant negative form of CAV1, defining a new mechanism by which disease-associated mutations in CAV1 impair caveolae assembly.

scholarly journals DNM1 encephalopathy

Neurology ◽  
2017 ◽  
Vol 89 (4) ◽  
pp. 385-394 ◽  
Author(s):  
Sarah von Spiczak ◽  
Katherine L. Helbig ◽  
Deepali N. Shinde ◽  
Robert Huether ◽  
Manuela Pendziwiat ◽  
...  
Keyword(s):  
Functional Data ◽  
De Novo ◽  
Structural Modeling ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Global Developmental Delay ◽  
Epilepsy Syndrome ◽  
De Novo Mutations ◽  
Phenotypic Data ◽  
Phenotypic Spectrum

Objective:To evaluate the phenotypic spectrum caused by mutations in dynamin 1 (DNM1), encoding the presynaptic protein DNM1, and to investigate possible genotype-phenotype correlations and predicted functional consequences based on structural modeling.Methods:We reviewed phenotypic data of 21 patients (7 previously published) with DNM1 mutations. We compared mutation data to known functional data and undertook biomolecular modeling to assess the effect of the mutations on protein function.Results:We identified 19 patients with de novo mutations in DNM1 and a sibling pair who had an inherited mutation from a mosaic parent. Seven patients (33.3%) carried the recurrent p.Arg237Trp mutation. A common phenotype emerged that included severe to profound intellectual disability and muscular hypotonia in all patients and an epilepsy characterized by infantile spasms in 16 of 21 patients, frequently evolving into Lennox-Gastaut syndrome. Two patients had profound global developmental delay without seizures. In addition, we describe a single patient with normal development before the onset of a catastrophic epilepsy, consistent with febrile infection-related epilepsy syndrome at 4 years. All mutations cluster within the GTPase or middle domains, and structural modeling and existing functional data suggest a dominant-negative effect on DMN1 function.Conclusions:The phenotypic spectrum of DNM1-related encephalopathy is relatively homogeneous, in contrast to many other genetic epilepsies. Up to one-third of patients carry the recurrent p.Arg237Trp variant, which is now one of the most common recurrent variants in epileptic encephalopathies identified to date. Given the predicted dominant-negative mechanism of this mutation, this variant presents a prime target for therapeutic intervention.

scholarly journals Attenuated TGFB signalling in macrophages decreases susceptibility to DMBA-induced mammary cancer in mice

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Xuan Sun ◽  
Sarah M. Bernhardt ◽  
Danielle J. Glynn ◽  
Leigh J. Hodson ◽  
Lucy Woolford ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Mammary Cancer ◽  
Breast Tissue ◽  
Mammary Gland Development ◽  
Transforming Growth Factor ◽  
Cancer Susceptibility ◽  
Dominant Negative ◽  
Target Cells ◽  
Tumour Development ◽  
Gland Development

AbstractBackgroundTransforming growth factor beta1 (TGFB1) is a multi-functional cytokine that regulates mammary gland development and cancer progression through endocrine, paracrine and autocrine mechanisms. TGFB1 also plays roles in tumour development and progression, and its increased expression is associated with an increased breast cancer risk. Macrophages are key target cells for TGFB1 action, also playing crucial roles in tumourigenesis. However, the precise role of TGFB-regulated macrophages in the mammary gland is unclear. This study investigated the effect of attenuated TGFB signalling in macrophages on mammary gland development and mammary cancer susceptibility in mice.MethodsA transgenic mouse model was generated, wherein a dominant negative TGFB receptor is activated in macrophages, in turn attenuating the TGFB signalling pathway specifically in the macrophage population. The mammary glands were assessed for morphological changes through wholemount and H&E analysis, and the abundance and phenotype of macrophages were analysed through immunohistochemistry. Another cohort of mice received carcinogen 7,12-dimethylbenz(a)anthracene (DMBA), and tumour development was monitored weekly. Human non-neoplastic breast tissue was also immunohistochemically assessed for latent TGFB1 and macrophage marker CD68.ResultsAttenuation of TGFB signalling resulted in an increase in the percentage of alveolar epithelium in the mammary gland at dioestrus and an increase in macrophage abundance. The phenotype of macrophages was also altered, with inflammatory macrophage markers iNOS and CCR7 increased by 110% and 40%, respectively. A significant decrease in DMBA-induced mammary tumour incidence and prolonged tumour-free survival in mice with attenuated TGFB signalling were observed. In human non-neoplastic breast tissue, there was a significant inverse relationship between latent TGFB1 protein and CD68-positive macrophages.ConclusionsTGFB acts on macrophage populations in the mammary gland to reduce their abundance and dampen the inflammatory phenotype. TGFB signalling in macrophages increases mammary cancer susceptibility potentially through suppression of immune surveillance activities of macrophages.

Bacterial origin of thymidylate and folate metabolism in Asgard Archaea

2021 ◽  
Author(s):  
Jonathan Filee ◽  
Hubert J. Becker ◽  
Lucille Mellottee ◽  
Zhihui LI ◽  
Jean-Christophe Lambry ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Lateral Gene Transfer ◽  
Phylogenetic Trees ◽  
De Novo ◽  
Horizontal Transmission ◽  
Folate Metabolism ◽  
Ecological Niches ◽  
Sequence Information ◽  
Amino Acid Utilization ◽  
Genome Wide

Little is known about the evolution and biosynthetic function of DNA precursor and the folate metabolism in the Asgard group of archaea. As Asgard occupy a key position in the archaeal and eukaryotic phylogenetic trees, we have exploited very recently emerged genome and metagenome sequence information to investigate these central metabolic pathways. Our genome-wide analyses revealed that the recently cultured Asgard archaeon Candidatus Prometheoarchaeum syntrophicum strain MK-D1 (Psyn) contains a complete folate-dependent network for the biosynthesis of DNA/RNA precursors, amino acids and syntrophic amino acid utilization. Altogether our experimental and computational data suggest that phylogenetic incongruences of functional folate-dependent enzymes from Asgard archaea reflect their persistent horizontal transmission from various bacterial groups, which has rewired the key metabolic reactions in an important and recently identified archaeal phylogenetic group. We also experimentally validated the functionality of the lateral gene transfer of Psyn thymidylate synthase ThyX. This enzyme uses bacterial-like folates efficiently and is inhibited by mycobacterial ThyX inhibitors. Our data raise the possibility that the thymidylate metabolism, required for de novo DNA synthesis, originated in bacteria and has been independently transferred to archaea and eukaryotes. In conclusion, our study has revealed that recent prevalent lateral gene transfer has markedly shaped the evolution of Asgard archaea by allowing them to adapt to specific ecological niches.

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