The Peroxisomal Targeting Signal 3 (PTS3) of the Budding Yeast Acyl-CoA Oxidase Is a Signal Patch

The specificity of import of peroxisomal matrix proteins is dependent on the targeting signals encoded within their amino acid sequences. Two known import signals, peroxisomal targeting signal 1 (PTS1), positioned at the C-termini and PTS2 located close to N-termini of these proteins are recognized by the Pex5p and Pex7p receptors, respectively. However, in several yeast species, including Saccharomyces cerevisiae, proteins exist that are efficiently imported into peroxisomes despite having neither PTS1 nor PTS2 and for which no other import signal has been determined. An example of such a protein is S. cerevisiae acyl-CoA oxidase (AOx) encoded by the POX1 gene. While it is known that its import is driven by its interaction with the N-terminal segment of Pex5p, which is separate from its C-terminal PTS1-recognizing tetratricopeptide domain, to date, no AOx polypeptide region has been implicated as critical for this interaction, and thus would constitute the long-sought PTS3 signal. Using random mutagenesis combined with a two-hybrid screen, we identified single amino acid residues within the AOx polypeptide that are crucial for this interaction and for the peroxisomal import of this protein. Interestingly, while scattered throughout the primary sequence, these amino acids come close to each other within two domains of the folded AOx. Although the role of one or both of these regions as the PTS3 signal is not finally proven, our data indicate that the signal guiding AOx into peroxisomal matrix is not a linear sequence but a signal patch

The essential function of Swc4p - a protein shared by two chromatin-modifying complexes of the yeast Saccharomyces cerevisiae - resides within its N-terminal part

The Swc4p protein, encoded by an essential gene, is shared by two chromatin-remodeling complexes in Saccharomyces cerevisiae cells: NuA4 (nucleosome acetyltransferase of H4) and SWR1. The SWR1 complex catalyzes ATP-dependent exchange of the nucleosomal histone H2A for H2AZ (Htz1p). The activity of NuA4 is responsible mainly for the acetylation of the H4 histone but also for the acetylation of H2A and H2AZ. In this work we investigated the role of the Swc4p protein. Using random mutagenesis we isolated a collection of swc4 mutants and showed that the essential function of Swc4p resides in its N-terminal part, within the first 269 amino acids of the 476-amino acid-long protein. We also demonstrated that Swc4p is able to accommodate numerous mutations without losing its functionality under standard growth conditions. However, when swc4 mutants were exposed to methyl methanesulfonate (MMS), hydroxyurea or benomyl, severe growth deficiencies appeared, pointing to an involvement of Swc4p in many chromatin-based processes. The mutants' phenotypes did not result from an impairment of histone acetylation, as in the mutant which bears the shortest isolated variant of truncated Swc4p, the level of overall H4 acetylation was unchanged

Cohesin Irr1/Scc3 is likely to influence transcription in Saccharomyces cerevisiae via interaction with Mediator complex.

The evolutionarily conserved proteins forming sister chromatid cohesion complex are also involved in the regulation of gene transcription. The participation of SA2p (mammalian ortholog of yeast Irr1p, associated with the core of the complex) in the regulation of transcription is already described. Here we analyzed microarray profiles of gene expression of a Saccharomyces cerevisiae irr1-1/IRR1 heterozygous diploid strain. We report that expression of 33 genes is affected by the presence of the mutated Irr1-1p and identify those genes. This supports the suggested role of Irr1p in the regulation of transcription. We also indicate that Irr1p may interact with elements of transcriptional coactivator Mediator

Hem12, an enzyme of heme biosynthesis pathway, is monoubiquitinated by Rsp5 ubiquitin ligase in yeast cells.

Heme biosynthesis pathway is conserved in yeast and humans and hem12 yeast mutants mimic porphyria cutanea tarda (PCT), a hereditary human disease caused by mutations in the UROD gene. Even though mutations in other genes also affect UROD activity and predispose to sporadic PCT, the regulation of UROD is unknown. Here, we used yeast as a model to study regulation of Hem12 by ubiquitination and involvement of Rsp5 ubiquitin ligase in this process. We found that Hem12 is monoubiquitinated in vivo by Rsp5. Hem12 contains three conserved lysine residues located on the protein surface that can potentially be ubiquitinated and lysine K8 is close to the 36-LPEY-39 (PY) motif which binds WW domains of the Rsp5 ligase. The hem12-K8A mutation results in a defect in cell growth on a glycerol medium at 38oC but it does not affect the level of Hem12. The hem12-L36A,P37A mutations which destroy the PY motif result in a more profound growth defect on both, glycerol and glucose-containing media. However, after several passages on the glucose medium, the hem12-L36A,P37A cells adapt to the growth medium owing to higher expression of hem12-L36A,P37A gene and higher stability of the mutant Hem12-L36A,P37A protein. The Hem12 protein is downregulated upon heat stress in a Rsp5-independent way. Thus, Rsp5-dependent Hem12 monoubiquitination is important for its functioning, but not required for its degradation. Since Rsp5 has homologs among the Nedd4 family of ubiquitin ligases in humans, a similar regulation by ubiquitination might be also important for functioning of the human UROD

Suppressors of translation initiation defect in hem12 locus of Saccharomyces cerevisiae.

A system for the positive selection of transational initiation suppressors in S. cerevisiae has been developed. A mutant with an ATA initiation codon in the HEM12 gene, encoding uroporphyrinogen decarboxylase, was used to select cis- and trans-acting suppressors. These suppressors partially restore growth on nonfermentable carbon sources, such as glycerol, but still allow the accumulation of porphyrins. All extragenic suppressors are mapped to the SUI1 locus, encoding initiation factor eIF1. The effect of the hem12 mutation is also partially reversed by the known SUI3 suppressor encoding the β subunit of eIF2. In contrast, the sui2 suppressor encoding the α subunit of eIF2 does not affect the hem 12 phenotype. The intragenic suppressors are able to restore the translation of hem12 due to the generation of additional, in frame AUG codons upstream of the hem12-14 mutation. Mutational analysis of the HEM12 leader sequence was also performed to determine the role of small open reading frames (uORFs) present upstream of the HEM12 ORF. Studies on the expression of integrated hem12-1/4-lacZ fusion, devoid of all upstream ATGs, indicate a lack of regulatory effect of uORFs on HEM12 translation

Leczenie dyslipidemii w dobie pandemii Covid-19 – co nowego?

brakW dobie pandemii COVID-19 zmagamy się z problemem oznaczania kontrolnych lipidogram w oraz nieosiąganiem zalecanego stężenia choleterolu frakcji LDL (LDL-C). Ma to szczeg lne znaczenie u chorych wysokiego ryzyka sercowo-naczyniowego na podłożu miażdżycy. U tych chorych, dotychczas bez lek w hypolipemizujących przy stężeniu LDL-C ≥ 100 mg/dl można obecnie zalecić włączenie w pierwszym rzucie statyny o wysokiej intensywności obejmujących atorwastatynę 40–80 mg/d. lub rosuwastatynę 20–40 mg/d. w połączeniu z ezetimibem. Kolejną linię leczenia stanowią inhibitory PCSK-9, szczeg lnie przy wsp łistniejącym czynniku ryzyka, a w warunkach polskich zgodnie z kryteriami programu lekowego: dla chorych po zawale serca do 12 miesięcy, z wywiadem przebytego zawału serca i wielonaczyniową chorobą wieńcową lub miażdżycą tętnic innych niż wieńcowe (tętnic obwodowych lub udarem m zgu/przejściowym niedokrwieniem m zgu). Alternatywę do przeciwciał monoklonalnych dawkowanych co 2 tygodnie może stanowić zarejestrowany już inklisiran, lek podawany dwa razy do roku, będący obecnie w 3 fazie badań klinicznych ukierunkowanych na redukcję incydent w sercowo-naczyniowych

Hodgkin’s lymphoma during pregnancy – case report

The incidence of hematologic malignancies in pregnancy ranges from 1:1000–1:10 000, with the most common lymphomas (1:1000–1:6000), Hodgkin’s lymphoma in particular. This paper describes a case of Hodgkin’s lymphoma diagnosed in a 36-year-old pregnant woman. The coexistence of pregnancy renders both the diagnosis and treatment more difficult. The signs of the disease may overlap with the symptoms associated with physiological pregnancy. The diagnosis is based on histopathological examination of the lesioned lymph node. The use of imaging techniques such as computed tomography and positron emission tomography should be avoided. Magnetic resonance and chest X-ray are acceptable; and there are no limitations for the use of ultrasound imaging. It is suggested that chemotherapy be delayed until the second trimester. The ABVD regimen is a standard treatment. In the case of disease progression, pregnancy termination and treatment outside pregnancy should be considered. In the case of pregnancy continuation, BEACOPP regimen may be used with optional, complementary radiotherapy. Treatment results for Hodgkin’s lymphoma diagnosed during pregnancy do not seem worse compared with age-matched groups. The management of pregnant patients with hematologic cancer requires care provided by a multidisciplinary team. Therapeutic decisions must account for the wellbeing of both, the mother and the fetus. The birth should be scheduled between courses so as to avoid pancytopenia in the patient and the newborn. The incidence of hematologic malignancies during pregnancy is rare, therefore it seems reasonable to collect data in the international registry in order to allow for an objective assessment of epidemiology, risk factors and treatment options.Nowotwory hematologiczne występują u ciężarnych z częstością 1:1000–1:10 000. Wśród tych nowotworów najczęstsze są chłoniaki (1:1000–1:6000), a w tej grupie – chłoniaki Hodgkina. W pracy opisano przypadek chłoniaka Hodgkina rozpoznanego w ciąży u 36-letniej kobiety. Współistnienie ciąży utrudnia zarówno rozpoznanie, jak i leczenie. Objawy przedmiotowe mogą nakładać się na dolegliwości towarzyszące fizjologicznej ciąży. Rozpoznanie ustalane jest na podstawie badania histopatologicznego zmienionego węzła chłonnego. Badania obrazowe, takie jak tomografia komputerowa i pozytonowa emisyjna tomografia komputerowa, nie powinny być przeprowadzane. Dopuszcza się wykonanie rezonansu magnetycznego i zdjęcia rentgenowskiego klatki piersiowej; nie ma ograniczeń co do badań ultrasonograficznych. Sugeruje się przesunięcie rozpoczęcia chemioterapii na II trymestr. Standardem leczenia jest program ABVD. W przypadku progresji choroby należy rozważyć zakończenie ciąży i leczenie jak poza ciążą. Przy kontynuacji ciąży można zastosować program BEACOPP, z ewentualną uzupełniającą radioterapią. Wyniki leczenia chłoniaka Hodgkina rozpoznanego w ciąży nie wydają się gorsze w porównaniu z grupami dobranymi wiekowo. Postępowanie z ciężarnymi pacjentkami z hematologicznym nowotworem wymusza opiekę zespołu wielospecjalistycznego. Decyzje terapeutyczne wymagają uwzględnienia zarówno dobra matki, jak i płodu. Poród dziecka powinien być zaplanowany pomiędzy kursami leczenia, tak aby uniknąć pancytopenii u chorej i noworodka. Ze względu na rzadkie występowanie nowotworów hematologicznych w ciąży wydaje się zasadne zbieranie danych w międzynarodowym rejestrze, co pozwoli na obiektywną ocenę epidemiologii, czynników ryzyka oraz opcji terapeutycznych

Usefulness of corregistration and post-processing of MR and interictal SPECT images for localization of epileptogenic focus in children : preliminary report

Background: Children with focal epilepsy unresponsive to anticonvulsant therapy may become surgical candidates. Inter-ictal SPECT (SPECT-IN) studies demonstrate an area of hypoperfusion within the seizure focus in up to 50% of patients. The goal of this study was to evaluate the usefulness of corregistration of MR and SPECT-IN images for localization of the epileptogenic focus. Material/Methods: Brain MRI and SPECT-IN were performed in 20 children (mean age 9.5). We found multifocal (3-6 perfusion deficits in 10 patients) or diffuse perfusion deficits (lobar) in all patients. In fused MR and SPECT images we evaluated average activity in volumes-of-interest (VOIs) outlined in each gray matter region with deficits. Average VOI activity below average total brain activity with at least 15% difference to the mirror VOI in the brain cortex on the opposite side of was considered as "true" perfusion deficit (TPD). Results: In all children from our group, MRI and SPECT-IN image fusion and evaluation of TPD allowed to verify most of multifocal or diffuse deficits: in each of 12 patients we found 1 TPD, in each of 6 patients 2 TPD and in each of 2 patients 3 TPD. In 8 patients with 2 or 3 TPD we used scalp EEG or ictal SPECT for identification of one probable location of epileptogenic focus. Conclusions: In children with refractory focal epilepsy, image fusion of MRI and SPECT-IN with evaluation of TPD has potential clinical utility in localization of epileptogenic focus