Cellular Models in Schizophrenia Research

Schizophrenia (SZ) is a prevalent functional psychosis characterized by clinical behavioural symptoms and underlying abnormalities in brain function. Genome-wide association studies (GWAS) of schizophrenia have revealed many loci that do not directly identify processes disturbed in the disease. For this reason, the development of cellular models containing SZ-associated variations has become a focus in the post-GWAS research era. The application of revolutionary clustered regularly interspaced palindromic repeats CRISPR/Cas9 gene-editing tools, along with recently developed technologies for cultivating brain organoids in vitro, have opened new perspectives for the construction of these models. In general, cellular models are intended to unravel particular biological phenomena. They can provide the missing link between schizophrenia-related phenotypic features (such as transcriptional dysregulation, oxidative stress and synaptic dysregulation) and data from pathomorphological, electrophysiological and behavioural studies. The objectives of this review are the systematization and classification of cellular models of schizophrenia, based on their complexity and validity for understanding schizophrenia-related phenotypes.

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Genetic Analysis of Osteoblast Activity Identifies Zbtb40 as a Regulator of Osteoblast Activity and Bone Mass

10.1101/828525 ◽

2019 ◽

Author(s):

Madison L. Doolittle ◽

Gina M Calabrese ◽

Larry D. Mesner ◽

Dana A. Godfrey ◽

Robert D. Maynard ◽

...

Keyword(s):

Bone Formation ◽

Genetic Basis ◽

Association Studies ◽

Genome Wide Association Studies ◽

Loss Of Function ◽

Mineral Density ◽

Osteoblast Activity ◽

Genome Wide ◽

Increased Risk

ABSTRACTOsteoporosis is a genetic disease characterized by progressive reductions in bone mineral density (BMD) leading to an increased risk of fracture. Over the last decade, genome-wide association studies (GWASs) have identified over 1000 associations for BMD. However, as a phenotype BMD is challenging as bone is a multicellular tissue affected by both local and systemic physiology. Here, we focused on a single component of BMD, osteoblast-mediated bone formation in mice, and identified associations influencing osteoblast activity on mouse Chromosomes (Chrs) 1, 4, and 17. The locus on Chr. 4 was in an intergenic region between Wnt4 and Zbtb40, homologous to a locus for BMD in humans. We tested both Wnt4 and Zbtb40 for a role in osteoblast activity and BMD. Knockdown of Zbtb40, but not Wnt4, in osteoblasts drastically reduced mineralization. Additionally, loss-of-function mouse models for both genes exhibited reduced BMD. Our results highlight that investigating the genetic basis of in vitro osteoblast mineralization can be used to identify genes impacting bone formation and BMD.

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Humanized TREM2 mice reveal microglia-intrinsic and -extrinsic effects of R47H polymorphism

Journal of Experimental Medicine ◽

10.1084/jem.20171529 ◽

2018 ◽

Vol 215 (3) ◽

pp. 745-760 ◽

Cited By ~ 86

Author(s):

Wilbur M. Song ◽

Satoru Joshita ◽

Yingyue Zhou ◽

Tyler K. Ulland ◽

Susan Gilfillan ◽

...

Keyword(s):

Late Onset ◽

Association Studies ◽

Amyloid Β ◽

Genome Wide Association Studies ◽

Genome Wide ◽

Soluble Trem2 ◽

The Common ◽

Late Onset Dementia

Alzheimer’s disease (AD) is a neurodegenerative disease that causes late-onset dementia. The R47H variant of the microglial receptor TREM2 triples AD risk in genome-wide association studies. In mouse AD models, TREM2-deficient microglia fail to proliferate and cluster around the amyloid-β plaques characteristic of AD. In vitro, the common variant (CV) of TREM2 binds anionic lipids, whereas R47H mutation impairs binding. However, in vivo, the identity of TREM2 ligands and effect of the R47H variant remain unknown. We generated transgenic mice expressing human CV or R47H TREM2 and lacking endogenous TREM2 in the 5XFAD AD model. Only the CV transgene restored amyloid-β–induced microgliosis and microglial activation, indicating that R47H impairs TREM2 function in vivo. Remarkably, soluble TREM2 was found on neurons and plaques in CV- but not R47H-expressing 5XFAD brains, although in vitro CV and R47H were shed similarly via Adam17 proteolytic activity. These results demonstrate that TREM2 interacts with neurons and plaques duing amyloid-β accumulation and R47H impairs this interaction.

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Complex polymorphisms in endocytosis genes suggest alpha-cyclodextrin as a treatment for breast cancer

10.1101/152405 ◽

2017 ◽

Author(s):

Knut M. Wittkowski ◽

Christina Dadurian ◽

Martin P. Seybold ◽

Han Sang Kim ◽

Ayuko Hoshino ◽

...

Keyword(s):

Breast Cancer ◽

Animal Studies ◽

Association Studies ◽

Treatment Options ◽

Cell Cycle Control ◽

Genome Wide Association Studies ◽

Nucleotide Polymorphisms ◽

Genome Wide ◽

Estrogen Receptor Positive

AbstractMost breast cancer deaths are caused by metastasis and treatment options beyond radiation and cytotoxic drugs, which have severe side effects, and hormonal treatments, which are or become ineffective for many patients, are urgently needed. This study reanalyzed existing data from three genome-wide association studies (GWAS) using a novel computational biostatistics approach (muGWAS), which had been validated in studies of 600–2000 subjects in epilepsy and autism. MuGWAS jointly analyzes several neighboring single nucleotide polymorphisms while incorporating knowledge about genetics of heritable diseases into the statistical method and about GWAS into the rules for determining adaptive genome-wide significance.Results from three independent GWAS of 1000–2000 subjects each, which were made available under the National Institute of Health’s “Up For A Challenge” (U4C) project, not only confirmed cell-cycle control and receptor/AKT signaling, but, for the first time in breast cancer GWAS, also consistently identified many genes involved in endo-/exocytosis (EEC), most of which had already been observed in functional and expression studies of breast cancer. In particular, the findings include genes that translocate (ATP8A1, ATP8B1, ANO4, ABCA1) and metabolize (AGPAT3, AGPAT4, DGKQ, LPPR1) phospholipids entering the phosphatidylinositol cycle, which controls EEC. These novel findings suggest scavenging phospholipids via alpha-cyclodextrins (αCD) as a novel intervention to control local spread of cancer, packaging of exosomes (which prepare distant microenvironment for organ-specific metastases), and endocytosis of β1 integrins (which are required for spread of metastatic phenotype and mesenchymal migration of tumor cells).Beta-cyclodextrins (βCD) have already been shown to be effective inin vitroand animal studies of breast cancer, but exhibits cholesterol-related ototoxicity. The smaller αCDs also scavenges phospholipids, but cannot fit cholesterol. Anin-vitrostudy presented here confirms hydroxypropyl (HP)-αCD to be twice as effective as HPβCD against migration of human cells of both receptor negative and estrogen-receptor positive breast cancer.If the previous successful animal studies with βCDs are replicated with the safer and more effective αCDs, clinical trials of adjuvant treatment with αCDs are warranted. Ultimately, all breast cancer are expected to benefit from treatment with HPαCD, but women with triplenegative breast cancer (TNBC) will benefit most, because they have fewer treatment options and their cancer advances more aggressively.

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PICALM modulates autophagy activity and tau accumulation

Nature Communications ◽

10.1038/ncomms5998 ◽

2014 ◽

Vol 5 (1) ◽

Cited By ~ 123

Author(s):

Kevin Moreau ◽

Angeleen Fleming ◽

Sara Imarisio ◽

Ana Lopez Ramirez ◽

Jacob L. Mercer ◽

...

Keyword(s):

Genetic Risk ◽

Association Studies ◽

Genome Wide Association Studies ◽

Transgenic Models ◽

Autophagosome Formation ◽

Genome Wide ◽

Autophagy Pathway ◽

Autophagy Activity

Abstract Genome-wide association studies have identified several loci associated with Alzheimer’s disease (AD), including proteins involved in endocytic trafficking such as PICALM/CALM (phosphatidylinositol binding clathrin assembly protein). It is unclear how these loci may contribute to AD pathology. Here we show that CALM modulates autophagy and alters clearance of tau, a protein which is a known autophagy substrate and which is causatively linked to AD, both in vitro and in vivo. Furthermore, altered CALM expression exacerbates tau-mediated toxicity in zebrafish transgenic models. CALM influences autophagy by regulating the endocytosis of SNAREs, such as VAMP2, VAMP3 and VAMP8, which have diverse effects on different stages of the autophagy pathway, from autophagosome formation to autophagosome degradation. This study suggests that the AD genetic risk factor CALM modulates autophagy, and this may affect disease in a number of ways including modulation of tau turnover.

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Contributions of Function-Altering Variants in Genes Implicated in Pubertal Timing and Body Mass for Self-Limited Delayed Puberty

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2017-02147 ◽

2017 ◽

Vol 103 (2) ◽

pp. 649-659 ◽

Cited By ~ 10

Author(s):

Sasha R Howard ◽

Leonardo Guasti ◽

Ariel Poliandri ◽

Alessia David ◽

Claudia P Cabrera ◽

...

Keyword(s):

Body Mass ◽

Rare Variants ◽

Association Studies ◽

Delayed Puberty ◽

Age At Menarche ◽

Genome Wide Association Studies ◽

Genome Wide ◽

Whole Exome ◽

Timing Of Puberty

Abstract Context Self-limited delayed puberty (DP) is often associated with a delay in physical maturation, but although highly heritable the causal genetic factors remain elusive. Genome-wide association studies of the timing of puberty have identified multiple loci for age at menarche in females and voice break in males, particularly in pathways controlling energy balance. Objective/Main Outcome Measures We sought to assess the contribution of rare variants in such genes to the phenotype of familial DP. Design/Patients We performed whole-exome sequencing in 67 pedigrees (125 individuals with DP and 35 unaffected controls) from our unique cohort of familial self-limited DP. Using a whole-exome sequencing filtering pipeline one candidate gene [fat mass and obesity–associated gene (FTO)] was identified. In silico, in vitro, and mouse model studies were performed to investigate the pathogenicity of FTO variants and timing of puberty in FTO+/− mice. Results We identified potentially pathogenic, rare variants in genes in linkage disequilibrium with genome-wide association studies of age at menarche loci in 283 genes. Of these, five genes were implicated in the control of body mass. After filtering for segregation with trait, one candidate, FTO, was retained. Two FTO variants, found in 14 affected individuals from three families, were also associated with leanness in these patients with DP. One variant (p.Leu44Val) demonstrated altered demethylation activity of the mutant protein in vitro. Fto+/− mice displayed a significantly delayed timing of pubertal onset (P < 0.05). Conclusions Mutations in genes implicated in body mass and timing of puberty in the general population may contribute to the pathogenesis of self-limited DP.

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Scarless genome editing reveals risk SNP rs6983267-G and lncRNA CCAT2 dictate targetable PI3K signaling dependence in WNT-dysregulated CRC

10.21203/rs.3.rs-667797/v1 ◽

2021 ◽

Author(s):

Nicole B. Coggins ◽

Henriette O’Geen ◽

Paul C. Lott ◽

David J. Segal ◽

Luis Carvajal Carmona

Keyword(s):

Risk Allele ◽

Association Studies ◽

Genome Wide Association Studies ◽

Growth Factor Signaling ◽

Cellular Models ◽

Genome Wide ◽

Potential Biomarker ◽

Increased Risk ◽

Hct 116

Abstract Genome-wide association studies have identified numerous loci associated with increased risk for colorectal cancer (CRC), including 8q24.21 which contains a known enhancer of proto-oncogene MYC . However, the role of candidate functional SNP rs6983267 within this locus remains unclear. Here, we generate isogenic cellular models of risk SNP rs6983267 in human CRC line, HCT-116. Comprehensive molecular characterization reveals risk allele-G drives enhancer DNA contacts with downstream regions that include MYC . Absence of risk allele leads to activation of lncRNA CCAT2 . Rather than changes in MYC expression, we observe activation of alternative growth factor signaling pathways with loss of both risk allele and CCAT2 expression. Analysis of TCGA CRC cases demonstrates low CCAT2 expression combined with non-risk rs6983267 genotype correlate with higher frequency of PI3K mutations in CRC patients displaying WNT dysregulation. Together, these provide a potential biomarker for therapeutically targetable PI3K dysregulation in CRC and application in cancer precision medicine.

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Alzheimer's disease-associated P460L mutation in ephrin receptor type A1 (EphA1) leads to dysregulated Rho-GTPase signaling

10.1101/2021.06.17.448790 ◽

2021 ◽

Author(s):

Yoon Kim ◽

Gorka Lasso ◽

Hardik Patel ◽

Badri Vardarajan ◽

Ismael Santa-Maria ◽

...

Keyword(s):

Rho Gtpase ◽

Late Onset ◽

Association Studies ◽

Genome Wide Association Studies ◽

Genome Wide ◽

The Brain ◽

Receptor Tyrosine Kinase Family

Recently, late onset AD (LOAD) genome-wide association studies identified EphA1, a member of receptor tyrosine kinase family (RTK) as a disease associated loci. In the follow-up study where 3 independent LOAD cohorts were performed, a P460L coding mutation in EphA1 loci showed a significant association with LOAD. However, the role of EphA1 and P460L mutant EphA1 in AD is not fully understood. We have characterized this mutation biophysically and biochemically. Our structural in silico model and in vitro biochemical analysis demonstrate that EphA1-P460L mutation makes the receptor constitutively active suggesting a gain-of-toxic function leading to chronic EphA1 signaling in the brain. Moreover, we report that the EphA1 P460L variant triggers Rho-GTPase signaling dysregulation that could potentially contribute to spine morphology abnormalities and synaptic dysfunction observed in AD pathology.

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Vasculitis: Decade in Review

Current Rheumatology Reviews ◽

10.2174/1573397114666180726093731 ◽

2018 ◽

Vol 15 (1) ◽

pp. 14-22 ◽

Cited By ~ 1

Author(s):

Selcan Demir ◽

Hafize Emine Sönmez ◽

Seza Özen

Keyword(s):

Targeted Therapies ◽

Association Studies ◽

Genome Wide Association ◽

Genome Wide Association Studies ◽

Genetic Studies ◽

The Past ◽

Genome Wide ◽

New Perspective

Background: In the last decade, we have come to better understand and manage the vasculitides. The classification of vasculitides has been revised. Genome- wide association studies and linkage analyses have been undertaken in hope of better understanding the pathogenesis of vasculitides. Comprehensive genetic studies have highlighted new pathways that may guide us in more targeted therapies. Description of the monogenic forms of vasculitis, such as deficiency of adenosine deaminase type 2 (DADA2), Haploinsufficiency of A20 (HA20), have introduced a new perspective to vasculopathies, and introduced alternative treatments for these diseases. Conclusion: In this review, the important discoveries in pathogenesis and consensus treatment recommendations from the past decade will be summarized.

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Implication of sestrin3 in epilepsy and its comorbidities

Brain Communications ◽

10.1093/braincomms/fcaa130 ◽

2020 ◽

Author(s):

Francesca Lovisari ◽

Paolo Roncon ◽

Marie Soukoupova ◽

Giovanna Paolone ◽

Marilyne Labasque ◽

...

Keyword(s):

Brain Injury ◽

Association Studies ◽

Acquired Brain Injury ◽

Genome Wide Association Studies ◽

Knock Out ◽

Genome Wide ◽

Inflammatory Processes ◽

Anxiety Depression

Abstract Epilepsy is a serious neurological disorder affecting about 1% of the population worldwide. Epilepsy may arise as a result of acquired brain injury, or as a consequence of genetic predisposition. To date, genome-wide association studies and exome sequencing approaches have provided limited insights into the mechanisms of acquired brain injury. We have previously reported a pro-epileptic gene network, which is conserved across species, encoding inflammatory processes and positively regulated by sestrin 3 (SESN3). In this study, we investigated the phenotype of SESN3 knock-out rats in terms of susceptibility to seizures and observed a significant delay in status epilepticus onset in SESN3 knock-out compared to control rats. This finding confirms previous in vitro and in vivo evidence indicating that SESN3 may favor occurrence and/or severity of seizures. We also analyzed the phenotype of SESN3 knock-out rats for common comorbidities of epilepsy, i.e. anxiety, depression, and cognitive impairment. SESN3 knock-out rats proved less anxious compared to control rats in a selection of behavioral tests. Taken together, the present results suggest that SESN3 may regulate mechanisms involved in the pathogenesis of epilepsy and its comorbidities.

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Isobutyrylcarnitine as a Biomarker of OCT1 Activity and Interspecies Differences in its Membrane Transport

Frontiers in Pharmacology ◽

10.3389/fphar.2021.674559 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ole Jensen ◽

Johannes Matthaei ◽

Henry G. Klemp ◽

Marleen J. Meyer ◽

Jürgen Brockmöller ◽

...

Keyword(s):

Association Studies ◽

Experimental Studies ◽

Organic Cation Transporter ◽

Interindividual Variation ◽

Genome Wide Association Studies ◽

Blood Concentrations ◽

Genome Wide ◽

Organic Cation Transporter 1 ◽

Carnitine Derivatives

Genome-wide association studies have identified an association between isobutyrylcarnitine (IBC) and organic cation transporter 1 (OCT1) genotypes. Higher IBC blood concentrations in humans with active OCT1 genotypes and experimental studies with mouse OCT1 suggested an OCT1-mediated efflux of IBC. In this study, we wanted to confirm the suggested use of IBC as an endogenous biomarker of OCT1 activity and contribute to a better understanding of the mechanisms behind the association between blood concentrations of carnitine derivatives and OCT1 genotype. Blood and urine IBC concentrations were quantified in healthy volunteers regarding intra- and interindividual variation and correlation with OCT1 genotype and with pharmacokinetics of known OCT1 substrates. Furthermore, IBC formation and transport were studied in cell lines overexpressing OCT1 and its naturally occurring variants. Carriers of high-activity OCT1 genotypes had about 3-fold higher IBC blood concentrations and 2-fold higher amounts of IBC excreted in urine compared to deficient OCT1. This was likely due to OCT1 function, as indicated by the fact that IBC correlated with the pharmacokinetics of known OCT1 substrates, like fenoterol, and blood IBC concentrations declined with a 1 h time delay following peak concentrations of the OCT1 substrate sumatriptan. Thus, IBC is a suitable endogenous biomarker reflecting both, human OCT1 (hOCT1) genotype and activity. While murine OCT1 (mOCT1) was an efflux transporter of IBC, hOCT1 exhibited no IBC efflux activity. Inhibition experiments confirmed this data showing that IBC and other acylcarnitines, like butyrylcarnitine, 2-methylbutyrylcarnitine, and hexanoylcarnitine, showed reduced efflux upon inhibition of mOCT1 but not of hOCT1. IBC and other carnitine derivatives are endogenous biomarkers of hOCT1 genotype and phenotype. However, in contrast to mice, the mechanisms underlying the IBC-OCT1 correlation in humans is apparently not directly the OCT1-mediated efflux of IBC. A plausible explanation could be that hOCT1 mediates cellular concentrations of specific regulators or co-substrates in lipid and energy metabolism, which is supported by our in vitro finding that at baseline intracellular IBC concentration is about 6-fold lower alone by OCT1 overexpression.

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