The Janus transcription factor HapX controls fungal adaptation to both iron starvation and iron excess.

Balance of physiological levels of iron is essential for every organism. In Aspergillus fumigatus and other fungal pathogens, the transcription factor HapX mediates adaptation to iron limitation and consequently virulence by repressing iron consumption and activating iron uptake. Here, we demonstrate that HapX is also essential for iron resistance via activating vacuolar iron storage. We identified HapX protein domains that are essential for HapX functions during either iron starvation or high-iron conditions. The evolutionary conservation of these domains indicates their wide-spread role in iron sensing. We further demonstrate that a HapX homodimer and the CCAAT-binding complex (CBC) cooperatively bind an evolutionary conserved DNA motif in a target promoter. The latter reveals the mode of discrimination between general CBC and specific HapX/CBC target genes. Collectively, our study uncovers a novel regulatory mechanism mediating both iron resistance and adaptation to iron starvation by the same transcription factor complex with activating and repressing functions depending on ambient iron availability.

Deciphering the combinatorial DNA-binding code of the CCAAT-binding complex and the iron-regulatory basic region leucine zipper (bZIP) transcription factor HapX.

The heterotrimeric CCAAT-binding complex (CBC) is evolutionarily conserved in eukaryotic organisms, including fungi, plants, and mammals. The CBC consists of three subunits, which are named in the filamentous fungus Aspergillus nidulans HapB, HapC, and HapE. HapX, a fourth CBC subunit, was identified exclusively in fungi, except for Saccharomyces cerevisiae and the closely related Saccharomycotina species. The CBC-HapX complex acts as the master regulator of iron homeostasis. HapX belongs to the class of basic region leucine zipper transcription factors. We demonstrated that the CBC and HapX bind cooperatively to bipartite DNA motifs with a general HapX/CBC/DNA 2:1:1 stoichiometry in a class of genes that are repressed by HapX-CBC in A. nidulans during iron limitation. This combinatorial binding mode requires protein-protein interaction between the N-terminal domain of HapE and the N-terminal CBC binding domain of HapX as well as sequence-specific DNA binding of both the CBC and HapX. Initial binding of the CBC to CCAAT boxes is mandatory for DNA recognition of HapX. HapX specifically targets the minimal motif 5'-GAT-3', which is located at a distance of 11-12 bp downstream of the respective CCAAT box. Single nucleotide substitutions at the 5'- and 3'-end of the GAT motif as well as different spacing between the CBC and HapX DNA-binding sites revealed a remarkable promiscuous DNA-recognition mode of HapX. This flexible DNA-binding code may have evolved as a mechanism for fine-tuning the transcriptional activity of CBC-HapX at distinct target promoters.

[Treatment and LDL cholesterol adjustment in patients with high and very high cardiovascular risk in Germany compared with Europe - data from the SANTORINI registry]. / Behandlung und LDL-Cholesterin-Einstellung von Patienten mit hohem und sehr hohem kardiovaskulärem Risiko in Deutschland und im europäischen Vergleich ­ Daten des SANTORINI-Registers.

INTRODUCTION: Current 2019 ESC/EAS guidelines for the management of dyslipidemia recommend LDL cholesterol (LDL-C) goals according to the patients' cardiovascular (CV) risk. SANTORINI is the first large European observational study since the 2019 guidelines to assess whether lipid management in patients at high and very high CV risk has improved. METHODS: SANTORINI is a multinational, prospective, non-interventional, observational study in 9602 patients ≥ 18 years at high and very high CV risk requiring lipid-lowering therapy. Individual CV risk was assessed by the investigator. The primary study objective is to document, in a real-world setting, the effectiveness of current lipid management regarding LDL-C levels. RESULTS: For this analysis, complete recruitment data was available for 2086 patients in Germany and 6958 patients Europe. Investigators used the 2019 ESC/EAS guidelines as a basis for CV risk classification in > 50 % of the patients and classified 15.6 % (173/1112) of patients in Germany as high and 84.4 % (939/1112) as very high-risk (Europe: 20.7 % [743/3594] high, 79.3 % [2851/3594] very high CV risk). An independent re-calculation of the CV risk based on these guidelines classified 4.1 % (46/1112) of patients in Germany as high and 94.5 % (1051/1112) as very high-risk. Also in Europe, CV risk was underestimated in around 10 % of patients.At baseline, 59.5 % (1241/2086) patients in Germany and 52.6 % (3661/6958) patients in Europe received lipid-lowering monotherapy; 19.9 % (416/2086) and 25.2 % (1753/6958) of patients in Germany and Europe received combination therapy. 78.6 % (1640/2086) of patients in Germany missed the 2019 ESC/EAS guideline recommended LDL-C treatment goals (Europe: 71.1 % [4989/6958]). DISCUSSION: The 2019 ESC/EAS guideline recommendations are only implemented in a minority of patients. The study identifies opportunities for improvements in the prevention of CV diseases in Germany.