Zsuzsanna Fekete

Biogenesis of cytosolic ribosomes requires the essential iron-sulphur protein Rli1p and mitochondria.

Mitochondria perform a central function in the biogenesis of cellular iron–sulphur (Fe/S) proteins. It is unknown to date why this biosynthetic pathway is indispensable for life, the more so as no essential mitochondrial Fe/S proteins are known. Here, we show that the soluble ATP‐binding cassette (ABC) protein Rli1p carries N‐terminal Fe/S clusters that require the mitochondrial and cytosolic Fe/S protein biogenesis machineries for assembly. Mutations in critical cysteine residues of Rli1p abolish association with Fe/S clusters and lead to loss of cell viability. Hence, the essential character of Fe/S clusters in Rli1p explains the indispensable character of mitochondria in eukaryotes. We further report that Rli1p is associated with ribosomes and with Hcr1p, a protein involved in rRNA processing and translation initiation. Depletion of Rli1p causes a nuclear export defect of the small and large ribosomal subunits and subsequently a translational arrest. Thus, ribosome biogenesis and function are intimately linked to the crucial role of mitochondria in the maturation of the essential Fe/S protein Rli1p.

Question: Why are mitochondria essential for life?

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Prohepcidin binds to the HAMP promoter and autoregulates its own expression.

Hepcidin is the major regulatory peptide hormone of iron metabolism, encoded by the HAMP (hepcidin antimicrobial peptide) gene. Hepcidin is expressed mainly in hepatocytes, but is also found in the blood in both a mature and prohormone form. Although, the function of mature hepcidin and the regulation of the HAMP gene have been extensively studied, the intracellular localization and the fate of prohepcidin remains controversial. In the present study, we propose a novel role for prohepcidin in the regulation of its own transcription. Using indirect immunofluorescence and mCherry tagging, a portion of prohepcidin was detected in the nucleus of hepatocytes. Prohepcidin was found to specifically bind to the STAT3 (signal transducer and activator of transcription 3) site in the promoter of HAMP. Overexpression of prohepcidin in WRL68 cells decreased HAMP promoter activity, whereas decreasing the amount of prohepcidin caused increased promoter activity measured by a luciferase reporter-gene assay. Moreover, overexpression of the known prohepcidin-binding partner, α-1 antitrypsin caused increased HAMP promoter activity, suggesting that only the non-α-1 antitrypsin-bound prohepcidin affects the expression of its own gene. The results of the present study indicate that prohepcidin can bind to and transcriptionally regulate the expression of HAMP, suggesting a novel autoregulatory pathway of hepcidin gene expression in hepatocytes.

Hepcidin and its potential clinical utility

A number of pathophysiological conditions are related to iron metabolism disturbances. Some of them are well known, others are newly discovered or special. Hepcidin is a newly identified iron metabolism regulating hormone, which could be a promising biomarker for many disorders. In this review, we provide background information about mammalian iron metabolism, cellular iron trafficking, and the regulation of expression of hepcidin. Beside these molecular biological processes, we summarize the methods that have been used to determine blood and urine hepcidin levels and present those pathological conditions (cancer, inflammation, neurological disorders) when hepcidin measurement may have clinical relevance.

Hepatitis A-járvány a Dél-Dunántúlon: molekuláris összefüggések, epidemiológiai következtetések - 2006

INTRODUCTIONnHepatitis A virus (HAV) is one of the most important cause of fecally transmitted acute infectious hepatitis worldwide. In Hungary, beside the sporadic HAV infections, outbreaks also occur, particularly in Northeast part of the country where the subgenotype IA is endemic. The reported number of HAV cases was less than 10 per year in Southwest Hungary.nnnAIMSnA part of the European HAV surveillance, the authors aims were to follow and to analyze the outbreak of hepatitis A in Transdanubia (Southwest Hungary) in 2006 by molecular epidemiological methods.nnnMATERIALS AND METHODSnSera samples from symptomatic patients were tested prospectively by enzyme-immunoassay (EIA) and reverse transcription-polymerase chain reaction (RT-PCR) followed by sequence- and phylogenetic analysis.nnnRESULTSnBetween June and December 2006, a total of 115 serum samples were positive for HAV IgM antibody in Southwest Hungary. Thirty (76.9%) of the 39 samples were RT-PCR-positive and contain genetically identical subgenotype IB hepatitis A virus (HAV/Transdanubia/2006/HUN) which has 100% nucleotide identity to strain IT-MAR-02 from Italy in 2002. Until now, approximately 1200-1300 persons have been infected with the probably imported strain. The average age of patients was 18 years (years 1 to 80). In this study, detailed clinical and epidemiological data of the outbreak are presented.nnnCONCLUSIONSnOnly a prospective molecular epidemiological study could verify the connection between the first sporadic HAV cases in June, the outbreak in August and the endemic spread of the virus since September in Southwest Hungary. This epidemic calls attention to how a hepatitis A outbreak can develop anywhere and at any time in Hungary and to the importance of active HAV immunization in the primary prevention.

The C19S Substitution Enhances the Stability of Hepcidin While Conserving Its Biological Activity

Hepcidin, the key hormone of iron homeostasis is responsible for lowering the serum iron level through its interaction with iron exporter ferroportin. Thus, hepcidin agonists provide a promising opportunity in the treatment of iron disorders caused by lacking or decreased hepcidin expression. We investigated the importance of each of the eight highly conserved cysteines for the biological activity of hepcidin. Eight cysteine mutants were created with site directed mutagenesis. The binding ability of these hepcidin mutants to the hepcidin receptor ferroportin was determined using bacterial two-hybrid system and WRL68 human hepatic cells. The biological activity of hepcidin mutants was determined by western blot analysis of ferroportin internalization and ferroportin ubiquitination. To investigate the effect of mutant hepcidins on the iron metabolism of the WRL68 cells, total intracellular iron content was measured with a colorimetric assay. The stability of M6 hepcidin mutant was determined using ELISA technique. Our data revealed that serine substitution of the sixth cysteine (M6) yielded a biologically active but significantly more stable peptide than the original hormone. This result may provide a promising hepcidin agonist worth testing in animal models.

Hepatitis A-járvány a Dél-Dunántúlon: molekuláris összefüggések, epidemiológiai következtetések – 2006@@@Hepatitis A outbreak in Transdanubia (Hungary): molecular connections and epidemiological conclusions – 2006

INTRODUCTIONnHepatitis A virus (HAV) is one of the most important cause of fecally transmitted acute infectious hepatitis worldwide. In Hungary, beside the sporadic HAV infections, outbreaks also occur, particularly in Northeast part of the country where the subgenotype IA is endemic. The reported number of HAV cases was less than 10 per year in Southwest Hungary.nnnAIMSnA part of the European HAV surveillance, the authors aims were to follow and to analyze the outbreak of hepatitis A in Transdanubia (Southwest Hungary) in 2006 by molecular epidemiological methods.nnnMATERIALS AND METHODSnSera samples from symptomatic patients were tested prospectively by enzyme-immunoassay (EIA) and reverse transcription-polymerase chain reaction (RT-PCR) followed by sequence- and phylogenetic analysis.nnnRESULTSnBetween June and December 2006, a total of 115 serum samples were positive for HAV IgM antibody in Southwest Hungary. Thirty (76.9%) of the 39 samples were RT-PCR-positive and contain genetically identical subgenotype IB hepatitis A virus (HAV/Transdanubia/2006/HUN) which has 100% nucleotide identity to strain IT-MAR-02 from Italy in 2002. Until now, approximately 1200-1300 persons have been infected with the probably imported strain. The average age of patients was 18 years (years 1 to 80). In this study, detailed clinical and epidemiological data of the outbreak are presented.nnnCONCLUSIONSnOnly a prospective molecular epidemiological study could verify the connection between the first sporadic HAV cases in June, the outbreak in August and the endemic spread of the virus since September in Southwest Hungary. This epidemic calls attention to how a hepatitis A outbreak can develop anywhere and at any time in Hungary and to the importance of active HAV immunization in the primary prevention.

[Hepatitis A outbreak in Transdanubia (Hungary): molecular connections and epidemiological conclusions - 2006].

INTRODUCTIONnHepatitis A virus (HAV) is one of the most important cause of fecally transmitted acute infectious hepatitis worldwide. In Hungary, beside the sporadic HAV infections, outbreaks also occur, particularly in Northeast part of the country where the subgenotype IA is endemic. The reported number of HAV cases was less than 10 per year in Southwest Hungary.nnnAIMSnA part of the European HAV surveillance, the authors aims were to follow and to analyze the outbreak of hepatitis A in Transdanubia (Southwest Hungary) in 2006 by molecular epidemiological methods.nnnMATERIALS AND METHODSnSera samples from symptomatic patients were tested prospectively by enzyme-immunoassay (EIA) and reverse transcription-polymerase chain reaction (RT-PCR) followed by sequence- and phylogenetic analysis.nnnRESULTSnBetween June and December 2006, a total of 115 serum samples were positive for HAV IgM antibody in Southwest Hungary. Thirty (76.9%) of the 39 samples were RT-PCR-positive and contain genetically identical subgenotype IB hepatitis A virus (HAV/Transdanubia/2006/HUN) which has 100% nucleotide identity to strain IT-MAR-02 from Italy in 2002. Until now, approximately 1200-1300 persons have been infected with the probably imported strain. The average age of patients was 18 years (years 1 to 80). In this study, detailed clinical and epidemiological data of the outbreak are presented.nnnCONCLUSIONSnOnly a prospective molecular epidemiological study could verify the connection between the first sporadic HAV cases in June, the outbreak in August and the endemic spread of the virus since September in Southwest Hungary. This epidemic calls attention to how a hepatitis A outbreak can develop anywhere and at any time in Hungary and to the importance of active HAV immunization in the primary prevention.

Adenovírus 8-as típusa okozta járványos keratoconjunctivitis molekuláris diagnosztikája

INTRODUCTIONnBoth infectious and non-infectious forms of acute conjunctivitis are known. Viruses, especially different types of adenoviruses are the etiological agents of infectious epidemic conjunctivitis (conjunctivitis epidemica).nnnAIMSnThe authors aims were to describe an outbreak of keratoconjunctivitis and to detect the viral agent by molecular methods in Hungary.nnnMATERIALS AND METHODSnClassical epidemiological methods were used for investigation. Polymerase chain reaction (PCR) followed by sequencing were used for the detection of adenoviral hexon region from freshly collected conjunctival swabs.nnnRESULTSnBetween 9 October and 18 December 2006, a total of 60 patients became ill with keratoconjunctivitis in 7 settlements in Southwest Hungary. Mean age was 51,2 years. Conjunctivitis (100%), lacrimation (94%), foreign body sensation (83%), and dim vision (76%) were the main clinical symptoms. Both eyes were affected in half of the cases. Direct contact was the main transmission route including nosocomial spread associated with ophthalmology practices. Five (62.5%) of 8 conjunctival swabs were PCR-positive for adenovirus type 8 (HAdV8/Baranya/2006/HUN; EF210714) which was genetically identical to adenovirus strain detected in Austria in 2004 (DQ149614).nnnCONCLUSIONSnThe outbreak of keratoconjunctivitis was partially associated with nosocomial infection caused by type 8 adenovirus. Both the recognition of the clinical illness, laboratory diagnosis and public health measures are necessary for the prevention of keratoconjunctivitis infection and epidemic.

Adenovírus 8-as típusa okozta járványos keratoconjunctivitis molekuláris diagnosztikája@@@Molecular detection of adenovirus type 8 epidemic keratoconjunctivitis in Hungary

INTRODUCTIONnBoth infectious and non-infectious forms of acute conjunctivitis are known. Viruses, especially different types of adenoviruses are the etiological agents of infectious epidemic conjunctivitis (conjunctivitis epidemica).nnnAIMSnThe authors aims were to describe an outbreak of keratoconjunctivitis and to detect the viral agent by molecular methods in Hungary.nnnMATERIALS AND METHODSnClassical epidemiological methods were used for investigation. Polymerase chain reaction (PCR) followed by sequencing were used for the detection of adenoviral hexon region from freshly collected conjunctival swabs.nnnRESULTSnBetween 9 October and 18 December 2006, a total of 60 patients became ill with keratoconjunctivitis in 7 settlements in Southwest Hungary. Mean age was 51,2 years. Conjunctivitis (100%), lacrimation (94%), foreign body sensation (83%), and dim vision (76%) were the main clinical symptoms. Both eyes were affected in half of the cases. Direct contact was the main transmission route including nosocomial spread associated with ophthalmology practices. Five (62.5%) of 8 conjunctival swabs were PCR-positive for adenovirus type 8 (HAdV8/Baranya/2006/HUN; EF210714) which was genetically identical to adenovirus strain detected in Austria in 2004 (DQ149614).nnnCONCLUSIONSnThe outbreak of keratoconjunctivitis was partially associated with nosocomial infection caused by type 8 adenovirus. Both the recognition of the clinical illness, laboratory diagnosis and public health measures are necessary for the prevention of keratoconjunctivitis infection and epidemic.