Somatic and germline aberrations in homologous recombination repair genes among Chinese high-risk breast cancer patients by multi-gene next-generation sequencing.

INTRODUCTION: Recently, genes involved in homologous recombination repair (HRR) pathway have been extensively studied. However, the landscapes of HRR gene mutations remain poorly defined in Chinese high-risk breast cancer (BC) patients. Our study aims to identify the status of germline and somatic HRR gene mutations and their association with clinicopathological features in these patients. MATERIALS AND METHODS: A total of 100 high-risk BC patients from our institution who underwent paired peripheral blood germline and BC tissues somatic 26 genes next-generation sequencing (NGS) from January 2018 to July 2023 were enrolled for retrospective analysis. RESULTS: Out of 100 high-risk BC patients, 55 (55%) had at least one germline or somatic mutation in HRR genes. Among them, 22% carried germline pathogenic variants (19 BRCA1/2 and 3 non-BRCA genes), 9% harbored somatic pathogenic mutations (3 BRCA1/2 and 6 non-BRCA genes). Among high-risk factors, family history and early onset BC showed a correlation with HRR gene mutations (p < 0.05). BRCA1 germline and HRR gene somatic mutations showed a correlation with TNBC, but BRCA2 germline mutations were associated with Luminal B/HER2-negative BC (p < 0.05). Patients with HRR gene somatic pathogenic variant more likely had a lympho-vascular invasion and distant metastasis (p < 0.05). CONCLUSION: The prevalence of HRR gene germline and somatic mutations were higher in Chinese BC patients with high risk factors. We strongly recommend that these high-risk BC patients receive comprehensive gene mutation testing, especially HRR genes, which are not only related to genetic consultation for BC patients and provide a theoretical basis for necessary prevention and individualized treatment.

ACC SYNTHASE4 inhibits gibberellin biosynthesis and FLOWERING LOCUS T expression during citrus flowering.

Flowering is an essential process in fruit trees. Flower number and timing have a substantial impact on the yield and maturity of fruit. Ethylene and gibberellin (GA) play vital roles in flowering, but the mechanism of coordinated regulation of flowering in woody plants by GA and ethylene is still unclear. In this study, a lemon (Citrus limon L. Burm) 1-aminocyclopropane-1-carboxylic acid synthase gene (CiACS4) was overexpressed in Nicotiana tabacum and resulted in late flowering and increased flower number. Further transformation of citrus revealed that ethylene and starch content increased, and soluble sugar content decreased in 35S:CiACS4 lemon. Inhibition of CiACS4 in lemon resulted in effects opposite to that of 35S:CiACS4 in transgenic plants. Overexpression of the CiACS4-interacting protein ETHYLENE RESPONSE FACTOR3 (CiERF3) in N. tabacum resulted in delayed flowering and more flowers. Further experiments revealed that the CiACS4-CiERF3 complex can bind the promoters of FLOWERING LOCUS T (CiFT) and GOLDEN2-LIKE (CiFE) and suppress their expression. Moreover, overexpression of CiFE in N. tabacum led to early flowering and decreased flowers, and ethylene, starch, and soluble sugar contents were opposite to those in 35S:CiACS4 transgenic plants. Interestingly, CiFE also bound the promoter of CiFT. Additionally, GA3 and 1-aminocyclopropanecarboxylic acid (ACC) treatments delayed flowering in adult citrus, and treatment with GA and ethylene inhibitors increased flower number. ACC treatment also inhibited the expression of CiFT and CiFE. This study provides a theoretical basis for the application of ethylene to regulate flower number and mitigate the impacts of extreme weather on citrus yield due to delayed flowering.

Zebrafish Znfl1 proteins control the expression of hoxb1b gene in the posterior neuroectoderm by acting upstream of pou5f3 and sall4 genes.

Transcription factors play crucial roles in patterning posterior neuroectoderm. Previously, zinc finger transcription factor znfl1 was reported to be expressed in the posterior neuroectoderm of zebrafish embryos. However, its roles remain unknown. Here, we report that there are 13 copies of znfl1 in the zebrafish genome, and all the paralogues share highly identical protein sequences and cDNA sequences. When znfl1s are knocked down using a morpholino to inhibit their translation or dCas9-Eve to inhibit their transcription, the zebrafish gastrula displays reduced expression of hoxb1b, the marker gene for the posterior neuroectoderm. Further analyses reveal that diminishing znfl1s produces the decreased expressions of pou5f3, whereas overexpression of pou5f3 effectively rescues the reduced expression of hoxb1b in the posterior neuroectoderm. Additionally, knocking down znfl1s causes the reduced expression of sall4, a direct regulator of pou5f3, in the posterior neuroectoderm, and overexpression of sall4 rescues the expression of pou5f3 in the knockdown embryos. In contrast, knocking down either pou5f3 or sall4 does not affect the expressions of znfl1s Taken together, our results demonstrate that zebrafish znfl1s control the expression of hoxb1b in the posterior neuroectoderm by acting upstream of pou5f3 and sall4.