Expanding the allelic spectrum of ELOVL4-related autosomal recessive neuro-ichthyosis.

BACKGROUND: Very long-chain fatty acids (VLCFAs) composed of more than 20 carbon atoms are essential in the biosynthesis of cell membranes in the brain, skin, and retina. VLCFAs are elongated beyond 28 carbon atoms by ELOVL4 enzyme. Variants in ELOVL4 are associated with three Mendelian disorders: autosomal dominant (AD) Stargardt-like macular dystrophy type 3, AD spinocerebellar ataxia, and autosomal recessive disorder congenital ichthyosis, spastic quadriplegia and impaired intellectual development (ISQMR). Only seven subjects from five unrelated families with ISQMR have been described, all of which have biallelic single-nucleotide variants. METHODS: We performed clinical exome sequencing on probands from four unrelated families with neuro-ichthyosis. RESULTS: We identified three novel homozygous ELOVL4 variants. Two of the families originated from the same Saudi tribe and had the exact homozygous exonic deletion in ELOVL4, while the third and fourth probands had two different novel homozygous missense variants. Seven out of the eight affected subjects had profound developmental delay, epilepsy, axial hypotonia, peripheral hypertonia, and ichthyosis. Delayed myelination and corpus callosum hypoplasia were seen in two of five subjects with brain magnetic rosonance imaging and cerebral atrophy in three. CONCLUSION: Our study expands the allelic spectrum of ELOVL4-related ISQMR. The detection of the same exonic deletion in two unrelated Saudi family from same tribe suggests a tribal founder mutation.

The Role of Semipurified Fractions Isolated from Quercus infectoria on Bone Metabolism by Using hFOB 1.19 Human Fetal Osteoblast Cell Model.

Background. Quercus infectoria (QI) is a plant used in traditional medicines in Asia. The plant was reported to contain various active phytochemical compounds that have potential to stimulate bone formation. However, the precise mechanism of the stimulation effect of QI on osteoblast has not been elucidated. The present study was carried out to isolate QI semipurified fractions from aqueous QI extract and to delineate the molecular mechanism of QI semipurified fraction that enhanced bone formation by using hFOB1.19 human fetal osteoblast cell model. Methods. Isolation of QI semipurified fractions was established by means of column chromatography and thin layer chromatography. Established QI semipurified fractions were identified using Liquid Chromatography-Mass Spectrometry (LC-MS). Cells were treated with derived QI semipurified fractions and investigated for mineralization deposition and protein expression level of BMP-2, Runx2, and OPN by ELISA followed gene expression analysis of BMP-2 and Runx2 by RT-PCR. Results. Column chromatography isolation and purification yield Fractions A, B, and C. LC-MS analysis reveals the presence of polyphenols in each fraction. Results show that QI semipurified fractions increased the activity and upregulated the gene expression of BMP-2 and Runx2 at day 1, day 3, and day 7. OPN activity increased in cells treated with QI semipurified fractions at day 1 and day 3. Meanwhile, at day 7, expression of OPN decreased in activity. Furthermore, the study showed that combination of Fractions A, B, and C with osteoporotic drug (pamidronate) further increased the activity and upregulated the gene expression of BMP-2 and Runx2. Conclusions. These findings demonstrated that polyphenols from semipurified fractions of QI enhanced bone formation through expression of the investigated bone-related marker that is its potential role when combined with readily available osteoporotic drug.

CENP-A Modifications on Ser68 and Lys124 Are Dispensable for Establishment, Maintenance, and Long-Term Function of Human Centromeres.

CENP-A is a histone H3 variant key to epigenetic specification of mammalian centromeres. Using transient overexpression of CENP-A mutants, two recent reports in Developmental Cell proposed essential centromere functions for post-translational modifications of human CENP-A. Phosphorylation at Ser68 was proposed to have an essential role in CENP-A deposition at centromeres. Blockage of ubiquitination at Lys124 was proposed to abrogate localization of CENP-A to the centromere. Following gene inactivation and replacement in human cells, we demonstrate that CENP-A mutants that cannot be phosphorylated at Ser68 or ubiquitinated at Lys124 assemble efficiently at centromeres during G1, mediate early events in centromere establishment at an ectopic chromosomal locus, and maintain centromere function indefinitely. Thus, neither Ser68 nor Lys124 post-translational modification is essential for long-term centromere identity, propagation, cell-cycle-dependent deposition, maintenance, function, or mediation of early steps in centromere establishment.

DNA Sequence-Specific Binding of CENP-B Enhances the Fidelity of Human Centromere Function.

Human centromeres are specified by a stably inherited epigenetic mark that maintains centromere position and function through a two-step mechanism relying on self-templating centromeric chromatin assembled with the histone H3 variant CENP-A, followed by CENP-A-dependent nucleation of kinetochore assembly. Nevertheless, natural human centromeres are positioned within specific megabase chromosomal regions containing α-satellite DNA repeats, which contain binding sites for the DNA sequence-specific binding protein CENP-B. We now demonstrate that CENP-B directly binds both CENP-A's amino-terminal tail and CENP-C, a key nucleator of kinetochore assembly. DNA sequence-dependent binding of CENP-B within α-satellite repeats is required to stabilize optimal centromeric levels of CENP-C. Chromosomes bearing centromeres without bound CENP-B, including the human Y chromosome, are shown to mis-segregate in cells at rates several-fold higher than chromosomes with CENP-B-containing centromeres. These data demonstrate a DNA sequence-specific enhancement by CENP-B of the fidelity of epigenetically defined human centromere function.