Search

Human pluripotent stem cells offer a limitless source of cells for regenerative medicine. They are also highly valuable as tools to study development and pathologies or as cellular substrates to screen and test new drugs. We generated human induced pluripotent stem cell (hiPSC) lines from two unrelated healthy control donors. Peripheral blood mononuclear cells (PBMCs) from these donors were reprogrammed by non-integrative viral transduction, had normal karyotypes and expressed pluripotency hallmarks.

Primary cilia (PC) are non-motile dynamic microtubule-based organelles that protrude from the surface of most mammalian cells. They emerge from the older centriole during the G1/G0 phase of the cell cycle, while they disassemble as the cells re-enter the cell cycle at the G2/M phase boundary. They function as signal hubs, by detecting and transducing extracellular signals crucial for many cell processes. Similar to most cell types, all neocortical neural stem and progenitor cells (NSPCs) have been shown harboring a PC allowing them to sense and transduce specific signals required for the normal cerebral cortical development. Here, we provide detailed protocols to generate and characterize two-dimensional (2D) and three-dimensional (3D) cell-based models from human induced pluripotent stem cells (hIPSCs) to further dissect the involvement of PC during neocortical development. In particular, we present protocols to study the PC biogenesis and function in 2D neural rosette-derived NSPCs including the transduction of the Sonic Hedgehog (SHH) pathway. To take advantage of the three-dimensional (3D) organization of cerebral organoids, we describe a simple method for 3D imaging of in toto immunostained cerebral organoids. After optical clearing, rapid acquisition of entire organoids allows detection of both centrosomes and PC on neocortical progenitors and neurons of the whole organoid. Finally, we detail the procedure for immunostaining and clearing of thick free-floating organoid sections preserving a significant degree of 3D spatial information and allowing for the high-resolution acquisition required for the detailed qualitative and quantitative analysis of PC biogenesis and function.

Purpose: Biallelic hypomorphic variants in PPA2, encoding the mitochondrial inorganic pyrophosphatase 2 protein, have been recently identified in individuals presenting with sudden cardiac death, occasionally triggered by alcohol intake or a viral infection. Here we report 20 new families harboring PPA2 variants., Methods: Synthesis of clinical and molecular data concerning 34 individuals harboring five previously reported PPA2 variants and 12 novel variants, 11 of which were functionally characterized., Results: Among the 34 individuals, only 6 remain alive. Twenty-three died before the age of 2 years while five died between 14 and 16 years. Within these 28 cases, 15 died of sudden cardiac arrest and 13 of acute heart failure. One case was diagnosed prenatally with cardiomyopathy. Four teenagers drank alcohol before sudden cardiac arrest. Progressive neurological signs were observed in 2/6 surviving individuals. For 11 variants, recombinant PPA2 enzyme activities were significantly decreased and sensitive to temperature, compared to wild-type PPA2 enzyme activity., Conclusion: We expand the clinical and mutational spectrum associated with PPA2 dysfunction. Heart failure and sudden cardiac arrest occur at various ages with inter- and intrafamilial phenotypic variability, and presentation can include progressive neurological disease. Alcohol intake can trigger cardiac arrest and should be strictly avoided., (© 2021. The Author(s).)

Acrofrontofacionasal dysostosis type 1 (AFFND1) is an extremely rare disorder characterized by several dysmorphic features, skeletal abnormalities and intellectual disability, and described only in seven patients in the literature. A biallelic variant in the Neuroblastoma Amplified Sequence (NBAS) gene was recently identified in two Indian patients with AFFND1. Here we report genetic investigation of AFFND1 in the originally described Brazilian families and the identification of an extremely rare, recessively-inherited, intronic variant in the Phosphatidylinositol Glycan class B (PIGB) gene NC_000015.10 (NM_004855.4): c.795-19T > G) in the affected individuals. The PIGB gene encodes an enzyme involved in the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor, which is required for the post-translational modification of a large variety of proteins, enabling their correct cellular localization and function. Recessive variants in PIGB have previously been reported in individuals with a neurodevelopmental syndrome having partial overlap with AFFND1. In vitro assays demonstrated that the intronic variant leads to exon skipping, suggesting the Brazilian AFFND1 patients may be null for PIGB, in agreement with their severe clinical phenotype. These data increase the number of pathogenic variants in the PIGB gene, place AFFND1 among GPI deficiencies and extend the spectrum of phenotypes associated with GPI biosynthesis defects., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The genetic causes of multiple congenital anomalies are incompletely understood. Here, we report novel heterozygous predicted loss-of-function (LoF) and predicted damaging missense variants in the WW domain binding protein 11 (WBP11) gene in seven unrelated families with a variety of overlapping congenital malformations, including cardiac, vertebral, tracheo-esophageal, renal and limb defects. WBP11 encodes a component of the spliceosome with the ability to activate pre-messenger RNA splicing. We generated a Wbp11 null allele in mouse using CRISPR-Cas9 targeting. Wbp11 homozygous null embryos die prior to E8.5, indicating that Wbp11 is essential for development. Fewer Wbp11 heterozygous null mice are found than expected due to embryonic and postnatal death. Importantly, Wbp11 heterozygous null mice are small and exhibit defects in axial skeleton, kidneys and esophagus, similar to the affected individuals, supporting the role of WBP11 haploinsufficiency in the development of congenital malformations in humans. LoF WBP11 variants should be considered as a possible cause of VACTERL association as well as isolated Klippel-Feil syndrome, renal agenesis or esophageal atresia., (© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

MN1 encodes a transcriptional co-regulator without homology to other proteins, previously implicated in acute myeloid leukaemia and development of the palate. Large deletions encompassing MN1 have been reported in individuals with variable neurodevelopmental anomalies and non-specific facial features. We identified a cluster of de novo truncating mutations in MN1 in a cohort of 23 individuals with strikingly similar dysmorphic facial features, especially midface hypoplasia, and intellectual disability with severe expressive language delay. Imaging revealed an atypical form of rhombencephalosynapsis, a distinctive brain malformation characterized by partial or complete loss of the cerebellar vermis with fusion of the cerebellar hemispheres, in 8/10 individuals. Rhombencephalosynapsis has no previously known definitive genetic or environmental causes. Other frequent features included perisylvian polymicrogyria, abnormal posterior clinoid processes and persistent trigeminal artery. MN1 is encoded by only two exons. All mutations, including the recurrent variant p.Arg1295* observed in 8/21 probands, fall in the terminal exon or the extreme 3' region of exon 1, and are therefore predicted to result in escape from nonsense-mediated mRNA decay. This was confirmed in fibroblasts from three individuals. We propose that the condition described here, MN1 C-terminal truncation (MCTT) syndrome, is not due to MN1 haploinsufficiency but rather is the result of dominantly acting C-terminally truncated MN1 protein. Our data show that MN1 plays a critical role in human craniofacial and brain development, and opens the door to understanding the biological mechanisms underlying rhombencephalosynapsis., (© The Author(s) (2019). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

ZMIZ1 is a coactivator of several transcription factors, including p53, the androgen receptor, and NOTCH1. Here, we report 19 subjects with intellectual disability and developmental delay carrying variants in ZMIZ1. The associated features include growth failure, feeding difficulties, microcephaly, facial dysmorphism, and various other congenital malformations. Of these 19, 14 unrelated subjects carried de novo heterozygous single-nucleotide variants (SNVs) or single-base insertions/deletions, 3 siblings harbored a heterozygous single-base insertion, and 2 subjects had a balanced translocation disrupting ZMIZ1 or involving a regulatory region of ZMIZ1. In total, we identified 13 point mutations that affect key protein regions, including a SUMO acceptor site, a central disordered alanine-rich motif, a proline-rich domain, and a transactivation domain. All identified variants were absent from all available exome and genome databases. In vitro, ZMIZ1 showed impaired coactivation of the androgen receptor. In vivo, overexpression of ZMIZ1 mutant alleles in developing mouse brains using in utero electroporation resulted in abnormal pyramidal neuron morphology, polarization, and positioning, underscoring the importance of ZMIZ1 in neural development and supporting mutations in ZMIZ1 as the cause of a rare neurodevelopmental syndrome., (Copyright © 2018 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Human studies and some animal work have shown more docosahexaenoic acid (DHA) and arachidonic acid (ARA) was accumulated or converted from precursors in females compared to males. This study explored in-depth the effect of gender on fatty acid composition and polyunsaturated fatty acid metabolism in rats fed one of two well-defined diets containing 10% total fat. One diet contained 15% of linoleic acid (LA) and 3% of α-linolenic acid (ALA) of the total fatty acids (LA+ALA diet), while the other diet contained 15% LA and 0.05% ALA (LA diet). At the age of 20 weeks, all animals were orally administered a single dose of a mixture of deuterium-labeled LA and ALA. Caudal venous blood was then drawn at 0, 2, 4, 8, 12, 24, 48, 96 and 168h. The concentrations of the deuterated precursors and their metabolites in plasma total lipids were quantified by GC/MS negative chemical ionization. Endogenous fatty acids were quantified by GC/FID analysis. When expressed as the percentage of oral dosage, female rats accumulated more precursors and more products, deuterated DHA and deuterated n-6 docosapentaenoic acid ( 2 H 5 -DPAn-6), in plasma than did male rats in both the LA+ALA diet and the LA diet. For the endogenous non-labeled PUFA, greater concentrations of DHA and DPAn-6 were similarly observed in female rats compared to males within each diet. A lower concentration of non-labeled ARA was observed only in female rats fed the LA+ALA diet. In summary, greater endogenous and exogenous DHA and DPAn-6 was observed in female rat plasma and this was independent of dietary ALA status., (Published by Elsevier Ltd.)

Docosahexaenoic acid (DHA), a crucial nervous system n-3 PUFA, may be obtained in the diet or synthesized in vivo from dietary alpha-linolenic acid (LNA). We addressed whether DHA synthesis is regulated by the availability of dietary DHA in artificially reared rat pups, during p8 to p28 development. Over 20 days, one group of rat pups was continuously fed deuterium-labeled LNA (d5-LNA) and no other n-3 PUFA (d5-LNA diet), and a second group of rat pups was fed a d5-LNA diet with unlabeled DHA (d5-LNA + DHA diet). The rat pups were then euthanized, and the total amount of deuterium-labeled docosahexaenoic acid (d5-DHA) (synthesized DHA) as well as other n-3 fatty acids present in various body tissues, was quantified. In the d5-LNA + DHA group, the presence of dietary DHA led to a marked decrease (3- to 5-fold) in the total amount of d5-DHA that accumulated in all tissues that we examined, except in adipose. Overall, DHA accretion from d5-DHA was generally diminished by availability of dietary preformed DHA, inasmuch as this was found to be the predominant source of tissue DHA. When preformed DHA was unavailable, d5-DHA and unlabeled DHA were preferentially accreted in some tissues along with a net loss of unlabeled DHA from other organs.