Phylogenetic analysis of phytochrome A gene from Lablab purpureus (L.) Sweet

Background Phytochromes are the best characterized photoreceptors that perceive Red (R)/Far-Red (FR) signals and mediate key developmental responses in plants. It is well established that photoperiodic control of flowering is regulated by PHY A (phytochrome A) gene. So far, the members of PHY A gene family remains unexplored in Lablab purpureus, and therefore, their functions are still not deciphered. PHYA3 is the homologue of phytochrome A and known to be involved in dominant suppression of flowering under long day conditions by downregulating florigens in Glycine max. The present study is the first effort to identify and characterize any photoreceptor gene (PHYA3, in this study) in Lablab purpureus and decipher its phylogeny with related legumes. Results PHYA3 was amplified in Lablab purpureus cv GNIB-21 (photo-insensitive and determinate) by utilizing primers designed from GmPHYA3 locus of Glycine max. This study was successful in partially characterizing PHYA3 in Lablab purpureus (LprPHYA3) which is 2 kb longer and belongs to exon 1 region of PHYA3 gene. Phylogenetic analysis of the nucleotide and protein sequences of PHYA genes through MEGA X delineated the conservation and evolution of Lablab purpureus PHYA3 (LprPHYA3) probably from PHYA genes of Vigna unguiculata, Glycine max and Vigna angularis. A conserved basic helix-loop-helix motif bHLH69 was predicted having DNA binding property. Domain analysis of GmPHYA protein and predicted partial protein sequence corresponding to exon-1 of LprPHYA3 revealed the presence of conserved domains (GAF and PAS domains) in Lablab purpureus similar to Glycine max. Conclusion Partial characterization of LprPHYA3 would facilitate the identification of complete gene in Lablab purpureus utilizing sequence information from phylogenetically related species of Fabaceae. This would allow screening of allelic variants for LprPHYA3 locus and their role in photoperiod responsive flowering. The present study could aid in modulating photoperiod responsive flowering in Lablab purpureus and other related legumes in near future through genome editing.

A (GCC) Repeat in the Untranslated Region of Human SBF1 Departs from Hardy-Weinberg Equilibrium in Human and Links to Late-onset Neurocognitive Disorder.

The human SBF1 (SET binding factor 1) gene, alternatively known as MTMR5, is predominantly expressed in the brain, and its epigenetic dysregulation is linked to late-onset neurocognitive disorders (NCDs), such as Alzheimer’s disease. This gene contains a (GCC)-repeat at the interval between +1 and +60 of the transcription start site (SBF1-202 ENST00000380817.8). Sequencing of the SBF1 (GCC)-repeat in a sample of 542 Iranian individuals, consisting of late-onset NCDs (N=260) and controls (N=282) revealed a predominantly bi-allelic locus for this STR, consisting of 8 and 9 repeats, with allele frequencies ranging from 0.39 to 0.55, and four other alleles with frequencies of <0.03 across the two groups. Overall heterozygosity for the observed alleles was significantly less than expected in the NCD and control groups, at 22.3% and 16.31%, respectively (p=0.000). Specifically, the heterozygous 8/9 genotype was significantly less than expected in both case and control groups (Hardy-Weinberg disequilibrium, p=0.000), and significantly enriched in the NCD group (Yates corrected p=0.001). Skewed heterozygous genotypes were also detected for other allele combinations, such as 6/8 vs 6/9 across groups (p=0.000). Bioinformatics studies revealed that the number of (GCC)-repeats may change the RNA secondary structure and interaction sites across human exon 1. This STR was specifically expanded beyond 2-repeats in primates. In conclusion, we report a novel biological phenomenon in which there is indication of purifying selection against heterozygous genotypes at a STR locus in human, and skewed genotype compartment in late-onset NCD vs. controls. In view of the location of this STR in the 5′ UTR, RNA/RNA or RNA/DNA heterodimer formation of the involved genotypes and possible deleterious downstream events should be considered.

Case Report: Japanese Siblings of Cystic Fibrosis With a Novel Large Heterozygous Deletion in the CFTR Gene

Cystic fibrosis (CF) is a rare disease in the Japanese. The most common CFTR variant in Japanese CF patients is a large heterozygous deletion that can easily avoid detection by standard gene sequencing methods. We herein report a novel large heterozygous deletion in the CFTR gene in Japanese siblings with CF. A genetic analysis was performed in two patients (9-year-old boy and 5-month-old girl) who were clinically diagnosed with CF because of the positive result for the rapid fecal pancreatic elastase antigen test and the elevation of the sweat chloride concentration. In addition to conventional polymerase chain reaction (PCR) and direct sequencing, multiplex ligation-dependent probe amplification (MLPA) was performed to check for a large deletion and duplication of the CFTR gene. Based on MLPA findings, the breakpoint of heterozygous deletion was identified by real-time quantitative PCR followed by the sequence of the amplified junction fragment. In MLPA, the numbers of the fragments corresponding to exons 1, 16, 17a, and 17b and 234 nt and 747 nt upstream from the translation initiation codon of exon 1 in the CFTR gene and exon 3 in the ASZ1 gene were reduced by almost half. The c.2908+1085_3367+260del7201 variant (exon 16-17b deletion) was identified in one allele. The other allele had a large 137,567-bp deletion from g.117,361,112 (ASZ1 3′ flanking region) to g.117,498,678 (CFTR intron 1) on chromosome 7. Since the deletion variant lacked the entire promoter region of CFTR, CFTR mRNA would not be transcribed from the allele, indicating it to be a novel pathogenic variant causing CF. As large mutations are frequently detected in Japanese CF patients, MPLA can be useful when searching for variants.

Whole exome sequencing revealed a large deletion in EDAof a Vietnamese patient with hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (HED) (OMIM # 305100) is a congenital genetic disorder caused by mutations in EDA (NM_001399) on chromosome X. Children with HED have the abnormal development of epidermal structures such as skin, hair, nails, teeth, and sweat glands. The present study aimed to detect mutations in EDA of a Vietnamese family with a son having only five teeth and no sweat glands, using whole exome sequencing (WES) and multiplex PCR. The results showed that patient had a deletion of exon 1 in EDA (c.2_396del), which is likely to be inherited from the healthy mother. The results will partly contribute to molecular studies on HED, helping in genetic counseling and disease treatment.

Transmission-selective muscle pathology induced by active propagation of mutant huntingtin across the human neuromuscular synapse

A potential explanation for the spatiotemporal accumulation of pathological lesions in the brain of patients with neurodegenerative protein misfolding diseases (PMDs) is cell-to-cell transmission of aggregation-prone, misfolded proteins. Little is known about central to peripheral transmission and its contribution to pathology. We show that transmission of Huntington’s disease- (HD-) associated mutant HTT exon 1 (mHTTEx1) occurs across the neuromuscular junctions in human iPSC cultures and in vivo in wild-type mice. We found that transmission is an active and dynamic process, that happens prior to aggregate formation and is regulated by synaptic activity. Furthermore, we find that transmitted mHTTEx1 causes HD-relevant pathology at a molecular and functional level in human muscle cells, even in the presence of ubiquitous expression mHTTEx1. With this work we uncover a casual-link between mHTTEx1 synaptic transmission and pathology, highlighting the therapeutic potential in blocking toxic protein transmission in PMDs.

Distinct promoter regions of the oxytocin receptor gene are hypomethylated in Prader-Willi syndrome and in Prader-Willi syndrome associated psychosis

Background: Prader-Willi syndrome (PWS) is a rare neurodevelopmental disorder caused by a loss of usually paternally expressed, maternally imprinted genes located on chromosome 15q11-q13. Individuals with PWS display a specific behavioral phenotype and have a higher susceptibility than the general population for certain psychiatric conditions, especially psychosis. An impairment of the oxytocin system has been described in Prader-Willi syndrome, but has not yet been investigated on the epigenetic level. Recent studies have pointed out altered methylation patterns of the oxytocin receptor gene (OXTR) in various psychiatric disorders, including psychosis. Methods: In this study, we investigated methylation rates of CpG dinucleotides in the promoter region of the oxytocin receptor gene via bisulfite-sequencing using DNA extracted from peripheral blood samples of 31 individuals with PWS and 14 controls matched for age, sex and BMI. Results: Individuals with PWS show significantly lower methylation in the intron 1 region of the OXTR than neurotypical controls (p=0.012). Furthermore, male PWS subjects with psychosis show significantly lower methylation of the OXTR exon 1 region than those without psychosis (p=0.002). Transcription factor binding site analysis revealed E2F1 as a transcription factor potentially binding to the exon 1 region. E2F1 is physiologically regulated by Necdin, an anti-apoptotic protein whose corresponding gene is located within the PWS locus. Conclusion: This study provides evidence of a disruption of the Oxytocin system on an epigenetic level in PWS in general and in individuals with PWS and psychosis.

Huntingtin Ubiquitination Mechanisms and Novel Possible Therapies to Decrease the Toxic Effects of Mutated Huntingtin

Huntington Disease (HD) is a dominant, lethal neurodegenerative disorder caused by the abnormal expansion (>35 copies) of a CAG triplet located in exon 1 of the HTT gene encoding the huntingtin protein (Htt). Mutated Htt (mHtt) easily aggregates, thereby inducing ER stress that in turn leads to neuronal injury and apoptosis. Therefore, both the inhibition of mHtt aggregate formation and the acceleration of mHtt degradation represent attractive strategies to delay HD progression, and even for HD treatment. Here, we describe the mechanism underlying mHtt degradation by the ubiquitin–proteasome system (UPS), which has been shown to play a more important role than the autophagy–lysosomal pathway. In particular, we focus on E3 ligase proteins involved in the UPS and detail their structure–function relationships. In this framework, we discuss the possible exploitation of PROteolysis TArgeting Chimeras (PROTACs) for HD therapy. PROTACs are heterobifunctional small molecules that comprise two different ligands joined by an appropriate linker; one of the ligands is specific for a selected E3 ubiquitin ligase, the other ligand is able to recruit a target protein of interest, in this case mHtt. As a consequence of PROTAC binding, mHtt and the E3 ubiquitin ligase can be brought to a relative position that allows mHtt to be ubiquitinated and, ultimately, allows a reduction in the amount of mHtt in the cell.

sgRNA design for DLT gene editing using CRISPR-Cas9 and in-silico mutation prediction in Rice cv. Hawara Bunar

The DWARF AND LOW TILLERRING (DLT) gene is a transcription factor for a gene involved in Brassinosteroid (BR) biosynthesis. Manipulating BR biosynthesis will affect the height and tiller number of rice. CRISPR-Cas9 is an accurate tool to edit a gene sequence. The accuracy of site editing of the CRISPR-Cas9-mediated target gene editing is determined by the 20 nucleotide sequences in the sgRNA and the binding site known as the Protospacer Adjacent Motif (PAM). The study aimed to design sgRNA and predict the DLT gene mutation sites in rice cv. Hawara Bunar. The exon 1 of the DLT gene was amplified using a primer pair designed from the reference gene. The PCR product was then sequenced, and the sequence was used to design sgRNA. The study has designed sgRNA located on the targeted sequence that corresponds to the Gras family protein domain of the exon1 DLT gene. The mutation sites were predicted to be at the domain site through the alignment of the nucleotide and amino acid sequences of the DLT gene and the reference gene. It is predicted that mutations in the target site that corresponds to the protein domain will change the protein structure and its function.

Huntingtin structure is orchestrated by HAP40 and shows a polyglutamine expansion-specific interaction with exon 1

Huntington’s disease results from expansion of a glutamine-coding CAG tract in the huntingtin (HTT) gene, producing an aberrantly functioning form of HTT. Both wildtype and disease-state HTT form a hetero-dimer with HAP40 of unknown functional relevance. We demonstrate in vivo and in cell models that HTT and HAP40 cellular abundance are coupled. Integrating data from a 2.6 Å cryo-electron microscopy structure, cross-linking mass spectrometry, small-angle X-ray scattering, and modeling, we provide a near-atomic-level view of HTT, its molecular interaction surfaces and compacted domain architecture, orchestrated by HAP40. Native mass spectrometry reveals a remarkably stable hetero-dimer, potentially explaining the cellular inter-dependence of HTT and HAP40. The exon 1 region of HTT is dynamic but shows greater conformational variety in the polyglutamine expanded mutant than wildtype exon 1. Our data provide a foundation for future functional and drug discovery studies targeting Huntington’s disease and illuminate the structural consequences of HTT polyglutamine expansion.

Co-Occurrence of Fragile X Syndrome with a Second Genetic Condition: Three Independent Cases of Double Diagnosis

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and autism caused by the instability of a CGG trinucleotide repeat in exon 1 of the FMR1 gene. The co-occurrence of FXS with other genetic disorders has only been occasionally reported. Here, we describe three independent cases of FXS co-segregation with three different genetic conditions, consisting of Duchenne muscular dystrophy (DMD), PPP2R5D--related neurodevelopmental disorder, and 2p25.3 deletion. The co-occurrence of DMD and FXS has been reported only once in a young boy, while in an independent family two affected boys were described, the elder diagnosed with FXS and the younger with DMD. This represents the second case in which both conditions coexist in a 5-year-old boy, inherited from his heterozygous mother. The next double diagnosis had never been reported before: through exome sequencing, a girl with FXS who was of 7 years of age with macrocephaly and severe psychomotor delay was found to carry a de novo variant in the PPP2R5D gene. Finally, a maternally inherited 2p25.3 deletion associated with a decreased level of the MYT1L transcript, only in the patient, was observed in a 33-year-old FXS male with severe seizures compared to his mother and two sex- and age-matched controls. All of these patients represent very rare instances of genetic conditions with clinical features that can be modified by FXS and vice versa.