Huntington disease-like 2: insight into neurodegeneration from an African disease

Huntington disease (HD)-like 2 (HDL2) is a rare genetic disease caused by an expanded trinucleotide repeat in the JPH3 gene (encoding junctophilin 3) that shows remarkable clinical similarity to HD. To date, HDL2 has been reported only in patients with definite or probable African ancestry. A single haplotype background is shared by patients with HDL2 from different populations, supporting a common African origin for the expansion mutation. Nevertheless, outside South Africa, reports of patients with HDL2 in Africa are scarce, probably owing to limited clinical services across the continent. Systematic comparisons of HDL2 and HD have revealed closely overlapping motor, cognitive and psychiatric features and similar patterns of cerebral and striatal atrophy. The pathogenesis of HDL2 remains unclear but it is proposed to occur through several mechanisms, including loss of protein function and RNA and/or protein toxicity. This Review summarizes our current knowledge of this African-specific HD phenocopy and highlights key areas of overlap between HDL2 and HD. Given the aforementioned similarities in clinical phenotype and pathology, an improved understanding of HDL2 could provide novel insights into HD and other neurodegenerative and/or trinucleotide repeat expansion disorders.

Methylation‑associated inactivation of JPH3 and its effect on prognosis and cell biological function in HCC

In recent years, researchers have found that epigenetics plays an important role in the occurrence and development of hepatocellular carcinoma (HCC). DNA methylation is involved in the proliferation and metastasis of HCC. However, the junctophilin 3 (JPH3) level and the potential regulatory mechanism of its DNA methylation in HCC remain uncertain. In the present study, 73 HCC samples were enrolled to analyze the expression of JPH3. Reverse‑transcription quantitative PCR, western blotting and immunohistochemistry were used to detect the expression of JPH3 in HCC. Kaplan‑Meier method and Cox regression analysis were applied to evaluate the prognostic impact of JPH3 on HCC patients. DNA methylation‑specific PCR and bisulfite Sanger sequencing were used to detect the degree of DNA methylation of JPH3 in HCC. The demethylation drug 5‑Aza‑2'‑deoxycytidine (5‑Aza) was used to reduce the DNA methylation of JPH3. The role of JPH3 in the malignant biological behavior of HCC by promoting epithelial‑mesenchymal transition (EMT) was confirmed by functional cell experiments. The results showed that JPH3 exhibited low levels in HCC tissues and cell lines. HCC patients with low expression of JPH3 had poor survival outcomes. JPH3 had higher DNA methylation levels in HCC tissues and cell lines. When the demethylation drug 5‑Aza was used to reduce the degree of methylation of JPH3, its protein expression level was significantly increased and it significantly inhibited the malignant biological behavior of HCC cells. Additionally, effective increase in the expression of JPH3 through gene regulation technology also inhibited the proliferation, invasion and migration of HCC cells. After altering the DNA methylation level of JPH3, the EMT of HCC cells was also affected. Therefore, our study demonstrated the inactivation of JPH3 by promoter methylation and its function as a tumor suppressor in HCC. JPH3 may serve as a biomarker for early diagnosis and as a potential therapeutic target for HCC.

Targeting JP2: A New Treatment for Pulmonary Hypertension

Pulmonary hypertension (PH) is a disease with a complex etiology and high mortality rate. Abnormal pulmonary vasoconstriction and pulmonary vascular remodeling lead to an increase in mean pulmonary arterial blood pressure for which, and there is currently no cure. Junctophilin-2 (JP2) is beneficial for the assembly of junctional membrane complexes, the structural basis for excitation-contraction coupling that tethers the plasma membrane to the sarcoplasmic reticulum/endoplasmic reticulum and is involved in maintaining intracellular calcium concentration homeostasis and normal muscle contraction function. Recent studies have shown that JP2 maintains normal contraction and relaxation of vascular smooth muscle. In some experimental studies of drug treatments for PH, JP2 expression was increased, which improved pulmonary vascular remodeling and right ventricular function. Based on JP2 research to date, this paper summarizes the current understanding of JP2 protein structure, function, and related heart diseases and mechanisms and analyzes the feasibility and possible therapeutic strategies for targeting JP2 in PH.

Whole genome sequencing identifies a homozygous nonsense mutation in the JPH2 gene in Shih Tzu dogs with progressive retinal atrophy

Progressive retinal atrophy (PRA), common autosomal recessive disorder affecting several dog breeds including Shih Tzu, is characterized by degeneration of photoreceptors leading to blindness. To identify PRA genetic variants, three affected and 15 unaffected Shih Tzu and 20 non-Shih Tzu were recruited. Dogs underwent ophthalmologic examination and electroretinography, revealing hallmark retina pathological changes and an abnormal electroretinography in all affected dogs but not in unaffected dogs. WGS was performed. Non-synonymous homozygous variants were searched in coding regions of genes involved in retinal diseases/development; the criterion was that variants should only be present in affected dogs and should be absent in both unaffected and 46 genomes of dogs (from an available evolutionary database). Only one out of the 109 identified variants is predicted to harbor a high-impact consequence, a nonsense c.452A>C (p.L151X) in the JPH2 gene. The genotype of JPH2 variant in all 38 dogs was determined with Sanger sequencing. All three affected dogs, but none of the 35 unaffected, were homozygous for the nonsense variant. JPH2 has been previously found to be expressed in several excitable cells/tissues including retina photoreceptors. Hence, JPH2 is a candidate gene for PRA in Shih Tzu.

Exercise Training Reverses Lipotoxicity-induced Cardiomyopathy by Inhibiting HMGCS2

PURPOSE

This study aimed to determine the effect of exercise training on preventing lipotoxic cardiomyopathy and to investigate the role of the 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) and miR-344g-5p in cardiomyocytes.

METHODS

Male C57BL/6 mice were fed a 60% high-fat diet (HFD) for 12 wk then began swimming exercise or remained sedentary for 8 wk. Thereafter, cardiac function was assessed by echocardiography, and heart tissue and plasma were collected for further measurements. The molecular mechanism of exercise was investigated after treating Hmgcs2 siRNA in palmitate-induced neonatal mouse cardiomyocytes.

RESULTS

HFD induced myocardial hypertrophy and fibrosis and reduced coronary reserve and cardiac function. HMGCS2 levels increased, but junctophilin-2 (JPH2) levels decreased in HFD mice hearts. Such effects were attenuated by swimming exercise. Mechanistically, Hmgcs2 silencing prevented apoptosis and caspase-3 cleavage and elevated the expression of JPH2 in palmitate-stimulated cardiomyocytes. In addition, exercise promoted miR-344g-5p expression in HFD hearts. The overexpression of miR-344g-5p by chemical mimic reduced HMGCS2, apoptosis, and caspase-3 cleavage and elevated JPH2 expression in palmitate-induced cardiomyocytes.

CONCLUSION

Our results suggest that exercise limits lipid metabolic disorder, cardiac hypertrophy, and fibrosis and aids in the prevention of lipotoxic cardiomyopathy. Exercise-mediated cardioprotection by upregulating miR-344g-5p, which targets Hmgcs2 mRNA, prohibits HMGCS2 upregulation and thus lipotoxicity.

Structure-Based Deep Mining Reveals First-Time Annotations for 46 Percent of the Dark Annotation Space of the 9,671-Member Superproteome of the Nucleocytoplasmic Large DNA Viruses

We conducted an exhaustive search for three-dimensional structural homologs to the proteins of 20 key phylogenetically distinct nucleocytoplasmic DNA viruses (NCLDV). Structural matches covered 429 known protein domain superfamilies, with the most highly represented being ankyrin repeat, P-loop NTPase, F-box, protein kinase, and membrane occupation and recognition nexus (MORN) repeat. Domain superfamily diversity correlated with genome size, but a diversity of around 200 superfamilies appeared to correlate with an abrupt switch to paralogization. Extensive structural homology was found across the range of eukaryotic RNA polymerase II subunits and their associated basal transcription factors, with the coordinated gain and loss of clusters of subunits on a virus-by-virus basis. The total number of predicted endonucleases across the 20 NCLDV was nearly quadrupled from 36 to 132, covering much of the structural and functional diversity of endonucleases throughout the biosphere in DNA restriction, repair, and homing. Unexpected findings included capsid protein-transcription factor chimeras; endonuclease chimeras; enzymes for detoxification; antimicrobial peptides and toxin-antitoxin systems associated with symbiosis, immunity, and addiction; and novel proteins for membrane abscission and protein turnover.IMPORTANCE We extended the known annotation space for the NCLDV by 46%, revealing high-probability structural matches for fully 45% of the 9,671 query proteins and confirming up to 98% of existing annotations per virus. The most prevalent protein families included ankyrin repeat- and MORN repeat-containing proteins, many of which included an F-box, suggesting extensive host cell modulation among the NCLDV. Regression suggested a minimum requirement for around 36 protein structural superfamilies for a viable NCLDV, and beyond around 200 superfamilies, genome expansion by the acquisition of new functions was abruptly replaced by paralogization. We found homologs to herpesvirus surface glycoprotein gB in cytoplasmic viruses. This study provided the first prediction of an endonuclease in 10 of the 20 viruses examined; the first report in a virus of a phenolic acid decarboxylase, proteasomal subunit, or cysteine knot (defensin) protein; and the first report of a prokaryotic-type ribosomal protein in a eukaryotic virus.