HIRA Gene is Lower Expressed in the Myocardium of Patients with Tetralogy of Fallot

HIRA vs. DAXX: the two axes shaping the histone H3.3 landscape

H3.3, the most common replacement variant for histone H3, has emerged as an important player in chromatin dynamics for controlling gene expression and genome integrity. While replicative variants H3.1 and H3.2 are primarily incorporated into nucleosomes during DNA synthesis, H3.3 is under the control of H3.3-specific histone chaperones for spatiotemporal incorporation throughout the cell cycle. Over the years, there has been progress in understanding the mechanisms by which H3.3 affects domain structure and function. Furthermore, H3.3 distribution and relative abundance profoundly impact cellular identity and plasticity during normal development and pathogenesis. Recurrent mutations in H3.3 and its chaperones have been identified in neoplastic transformation and developmental disorders, providing new insights into chromatin biology and disease. Here, we review recent findings emphasizing how two distinct histone chaperones, HIRA and DAXX, take part in the spatial and temporal distribution of H3.3 in different chromatin domains and ultimately achieve dynamic control of chromatin organization and function. Elucidating the H3.3 deposition pathways from the available histone pool will open new avenues for understanding the mechanisms by which H3.3 epigenetically regulates gene expression and its impact on cellular integrity and pathogenesis.

Right Ventricle and Epigenetics: A Systematic Review

There is an increasing recognition of the crucial role of the right ventricle (RV) in determining the functional status and prognosis in multiple conditions. In the past decade, the epigenetic regulation (DNA methylation, histone modification, and non-coding RNAs) of gene expression has been raised as a critical determinant of RV development, RV physiological function, and RV pathological dysfunction. We thus aimed to perform an up-to-date review of the literature, gathering knowledge on the epigenetic modifications associated with RV function/dysfunction. Therefore, we conducted a systematic review of studies assessing the contribution of epigenetic modifications to RV development and/or the progression of RV dysfunction regardless of the causal pathology. English literature published on PubMed, between the inception of the study and 1 January 2023, was evaluated. Two authors independently evaluated whether studies met eligibility criteria before study results were extracted. Amongst the 817 studies screened, 109 studies were included in this review, including 69 that used human samples (e.g., RV myocardium, blood). While 37 proposed an epigenetic-based therapeutic intervention to improve RV function, none involved a clinical trial and 70 are descriptive. Surprisingly, we observed a substantial discrepancy between studies investigating the expression (up or down) and/or the contribution of the same epigenetic modifications on RV function or development. This exhaustive review of the literature summarizes the relevant epigenetic studies focusing on RV in human or preclinical setting.

Severe Hypocalcemia in the Adolescent as the Only Manifestation of <i>22q11</i> Microdeletion Syndrome: Clinical Case

Background. In this article, we would like to describe the atypical clinical picture and course of 22q11 microdeletion syndrome in a patient without specific phenotypic signs and symptoms typical for this disease.

Clinical case description. Male patient, 13 years old, was hospitalized for the first time with seizure and multiple spinal fractures caused by hypocalcemia. He was referred to rheumatologist and clinical geneticist after hospital stay. Differential diagnosis included not only various bones metabolic diseases, but also 22q11 deletion syndrome. Later it was confirmed via FISH test.

Conclusion. This clinical case proves once again the uniqueness of every single case, as well as the importance of comprehensive approach to the diagnosis and management of such patients.

Association between functional polymorphisms in the promoter of the miR-143/145 cluster and risk of conotruncal heart defects

Aim: Conotruncal heart defects (CTDs) are the most common form of congenital heart disease. We investigated the association of these two single-nucleotide polymorphisms (SNPs) in the promoter of miR-143/145 (rs353292 and rs4705343) with the susceptibility to CTDs in a Chinese population. Materials & methods: Two SNPs in the promoter of miR-143/145 (rs353292 and rs4705343) have been examined by PCR-RFLP methodology for 259 CTDs patients and 303 control subjects. Results: An association between SNP rs4705343 of miR-143/145 and CTDs has been confirmed in the Chinese Han population. Conclusion: Our results indicated that SNP rs4705343 in miR-143/145 is a potential genetic marker for CTDs in the Chinese Han population.

Role of lncRNA uc.457 in the differentiation and maturation of cardiomyocytes

Congenital heart disease (CHD) is the most common type of birth defect, and the leading cause of fetal mortality. The long noncoding RNA (lncRNA) uc.457 is differentially expressed in cardiac tissue from patients with a ventricular septal defect; however, its role in cardiac development and CHD remains unknown. In the present study, the role of uc.457 in the differentiation and maturation of cardiomyocytes was investigated. Bioinformatics approaches were employed to analyze putative transcription factor (TF) regulation, histone modifications and the biological functions of uc.457. Subsequently, uc.457 overexpression and small interfering RNA‑mediated knockdown were performed to evaluate the functional role of the lncRNA in the dimethyl sulfoxide‑induced differentiation of P19 cells into cardiomyocytes. Bioinformatics analyses predicted that uc.457 binds to TFs associated with cardiomyocyte growth and cardiac development. Cell Counting Kit‑8 assays demonstrated that uc.457 overexpression inhibited cell proliferation, whereas knockdown of uc.457 enhanced the proliferation of differentiating cardiomyocytes. Additionally, reverse transcription‑quantitative polymerase chain reaction and western blot analyses revealed that overexpression of uc.457 suppressed the mRNA and protein expression of histone cell cycle regulation defective homolog A, natriuretic peptide A, cardiac muscle troponin T and myocyte‑specific enhancer factor 2C. Collectively, the results indicated that overexpression of uc.457 inhibited the differentiation and proliferation of cardiomyocytes, suggesting that dysregulated uc.457 expression may be associated with CHD.