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Frontiers in Physiology 2022The heme biosynthesis (HB) involves eight subsequent enzymatic steps. Erythropoietic protoporphyria (EPP) is caused by loss-of-function mutations in the ferrochelatase...
The heme biosynthesis (HB) involves eight subsequent enzymatic steps. Erythropoietic protoporphyria (EPP) is caused by loss-of-function mutations in the ferrochelatase (FECH) gene, which in the last HB step inserts ferrous iron into protoporphyrin IX (PPIX) to form heme. The aim of this work was to for the first time analyze the mRNA expression of all HB genes in peripheral blood samples of patients with EPP having the same genotype FECH c.[215dupT]; [315-48T > C] as compared to healthy controls by highly sensitive and specific digital PCR assays (dPCR). We confirmed a decreased FECH mRNA expression in patients with EPP. Further, we found increased ALAS2 and decreased ALAS1, CPOX, PPOX and HMBS mRNA expression in patients with EPP compared to healthy controls. ALAS2 correlated with FECH mRNA expression (EPP: = 0.63, = 0.03 and controls: = 0.68, = 0.02) and blood parameters like PPIX (EPP: = 0.58 = 0.06). Our method is the first that accurately quantifies HB mRNA from blood samples with potential applications in the monitoring of treatment effects of mRNA modifying therapies , or investigation of the HB pathway and its regulation. However, our findings should be studied in separated blood cell fractions and on the enzymatic level.
PubMed: 35923227
DOI: 10.3389/fphys.2022.886194 -
Frontiers in Molecular Biosciences 20225-Aminolevulinate synthase (ALAS; E.C. 2.3.1.37) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the key regulatory step of porphyrin biosynthesis in... (Review)
Review
5-Aminolevulinate synthase (ALAS; E.C. 2.3.1.37) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the key regulatory step of porphyrin biosynthesis in metazoa, fungi, and α-proteobacteria. ALAS is evolutionarily related to transaminases and is therefore classified as a fold type I PLP-dependent enzyme. As an enzyme controlling the key committed and rate-determining step of a crucial biochemical pathway ALAS is ideally positioned to be subject to allosteric feedback inhibition. Extensive kinetic and mutational studies demonstrated that the overall enzyme reaction is limited by subtle conformational changes of a hairpin loop gating the active site. These findings, coupled with structural information, facilitated early prediction of allosteric regulation of activity via an extended C-terminal tail unique to eukaryotic forms of the enzyme. This prediction was subsequently supported by the discoveries that mutations in the extended C-terminus of the erythroid ALAS isoform (ALAS2) cause a metabolic disorder known as X-linked protoporphyria not by diminishing activity, but by enhancing it. Furthermore, kinetic, structural, and molecular modeling studies demonstrated that the extended C-terminal tail controls the catalytic rate by modulating conformational flexibility of the active site loop. However, the precise identity of any such molecule remains to be defined. Here we discuss the most plausible allosteric regulators of ALAS activity based on divergences in AlphaFold-predicted ALAS structures and suggest how the mystery of the mechanism whereby the extended C-terminus of mammalian ALASs allosterically controls the rate of porphyrin biosynthesis might be unraveled.
PubMed: 35911972
DOI: 10.3389/fmolb.2022.920668 -
Wideochirurgia I Inne Techniki... Jun 2022Erythropoietic protoporphyria is a hereditary defect in heme synthesis, causing protoporphyrin deposition and phototoxic reactions after exposure to light, especially at...
Erythropoietic protoporphyria is a hereditary defect in heme synthesis, causing protoporphyrin deposition and phototoxic reactions after exposure to light, especially at a wavelength of about 400 nm. Sensitivity to light may cause postoperative complications. Therefore, in open surgery protective filters are employed on surgical luminaires. The dangers of laparoscopy are little understood and the intensity of the light used can be high. To protect against phototoxic injury, we inserted an OG 530 filter in the video track. This filter blocks wavelengths below 470 nm. Three cholecystectomies and one sigmoidectomies were performed laparoscopically. The procedures were uneventful, and the patients suffered no adverse reactions, including phototoxic symptoms. The filter had a moderate influence on color perception and caused no significant restrictions on working conditions. We consider that it is appropriate to develop a relevant design to meet the suitable requirements for a durable filter holder in the laparoscopic video track.
PubMed: 35707342
DOI: 10.5114/wiitm.2022.115003 -
Skin Health and Disease Mar 2022The activation of melanocortin 1 receptor (MC1R) on melanocytes stimulates the production of eumelanin. A tridecapeptide α melanocyte-stimulating hormone (αMSH) is...
BACKGROUND
The activation of melanocortin 1 receptor (MC1R) on melanocytes stimulates the production of eumelanin. A tridecapeptide α melanocyte-stimulating hormone (αMSH) is known to induce skin pigmentation.
OBJECTIVES
We characterised the properties of a novel oral MC1R agonist dersimelagon (MT-7117) with respect to its specific binding to MC1R, downstream signalling and eumelanin production in experimental models.
METHODS
The competitive binding and production of intracellular cyclic adenosine 3', 5'-monophosphate in cells expressing recombinant melanocortin receptors were examined. A mouse melanoma cell line B16F1 was used for the evaluation of in vitro melanin production. The in vitro activity of MT-7117 was determined with αMSH and [Nle, D-Phe]-αMSH (NDP-αMSH) as reference comparators. The change of coat colour and skin pigmentation were evaluated after repeat administration of MT-7117 by oral gavage to C57BL/6J-A/+ mice and cynomolgus monkeys, respectively.
RESULTS
MT-7117 showed the highest affinity for human MC1R compared to the other melanocortin receptors evaluated and agonistic activity for human, cynomolgus monkey and mouse MC1R, with EC values in the nanomolar range. In B16F1 cells, MT-7117 increased melanin production in a concentration-dependent manner. In vivo, MT-7117 (≥0.3 mg/kg/day p.o.) significantly induced coat colour darkening in mice. MT-7117 (≥1 mg/kg/day p.o.) induced significant skin pigmentation in monkeys and complete reversibility was observed after cessation of its administration.
CONCLUSIONS
MT-7117 is a novel oral MC1R agonist that induces melanogenesis in vitro and in vivo, suggesting its potential application for the prevention of phototoxic reactions in patients with photodermatoses, such as erythropoietic protoporphyria and X-linked protoporphyria.
PubMed: 35665216
DOI: 10.1002/ski2.78 -
Diagnostics (Basel, Switzerland) May 2022The World Health Organization (WHO) describes "health" as a state of physical, mental, and social well-being and not merely the absence of disease or infirmity.... (Review)
Review
The World Health Organization (WHO) describes "health" as a state of physical, mental, and social well-being and not merely the absence of disease or infirmity. Therefore, a biopsychosocial approach should be considered as an integral part of patients' management. In this review, we summarize the available data starting from 1986 on the biological, psychological, and social aspects of porphyrias in order to provide a useful tool for clinicians about the missing knowledge within this field. Porphyrias are a group of rare metabolic disorders affecting the heme biosynthetic pathway and can be categorized into hepatic and erythropoietic. Here, a total of 20 articles reporting the psychological and the quality of life (QoL) data of porphyria patients affected by acute hepatic porphyrias (AHPs), Porphyria Cutanea Tarda (PCT), and Erythropoietic Protoporphyria (EPP) were analyzed. These 13 articles include reported quantitative methods using questionnaires, while the reaming articles employed qualitative descriptive approaches through direct interviews with patients by psychology professionals. We conclude that the use of questionnaires limits the complete description of all areas of a patient's life compared to a direct interview with specialists. However, only a combined use of these methods could be the best approach for the correct disorder management.
PubMed: 35626348
DOI: 10.3390/diagnostics12051193 -
Cellular Physiology and Biochemistry :... Apr 2022Cancer is a chaos of uncontrolled cell proliferation that has consistently invented new circuitry programs to operate inside the cell machinery. Globally, cancer...
Cancer is a chaos of uncontrolled cell proliferation that has consistently invented new circuitry programs to operate inside the cell machinery. Globally, cancer statistics account for 65% of mortality worldwide, mainly due to the adoption of lifestyle behaviours. In 2020, FDA approved 40 new drugs, out of which 16 (40%) were approved as cancer drugs. Overall, the risk of dying from cancer decreased, but further reductions in cancer death rates can be accelerated by applying existing cancer control knowledge across all the population segments, emphasising those in the lowest socio-economic and other disadvantaged population. Various therapeutic regimes, including low-molecular-weight inhibitors, targeting oncogenic signaling pathways are under development. However, the pitfall of targeted therapies is the quick emergence of acquired drug resistance encumbered with toxic side effects. Several FDA acclaimed therapeutic legacies or biosimilars earmarked signaling pathways of rare diseases (cystic fibrosis, erythropoietic protoporphyria, neuromyelitis optica spectrum disorder, tenosynovial giant cell tumor, sickle cell disease, systemic sclerosis-associated interstitial lung disease, muscular dystrophy), neurological and psychiatric disorders, infectious diseases, heart, lung, circulatory, endocrine diseases, autoimmune conditions, cancers and blood disorders. When cancer progresses, these signals develop specific characteristics that can be targeted for anti-cancer therapy. The designer inhibitors have emerged as novel pharmaceutical interventions that aim to block the pathways in an effort to reverse the abnormal phenotype of the cancer cells. Numerous cell-signaling channels have evolved and invigorated to make off three-dimensional feedback networks. The magnitude of accessible information by pathways occupies curated information as a consortium. To fully appreciate the pivotal roles that signaling cascades play in tumor development, it is necessary to understand the involved signaling cascades in the interaction between cancer cells. The prime endeavour is to canonically curate all signaling pathways involving cell cycle, EGFR, MAPK, GPCR, PI3K/ AKT/mTOR, immune checkpoints, nuclear receptors, janus kinase, transcription activators etc., involving the manipulation of genetic and nuclear receptors. Here, we will summarize the vast amount of information describing the signals that mediate crosstalk between cancer cells and the targets related to this crosstalk.
Topics: Antineoplastic Agents; Biosimilar Pharmaceuticals; Cell Proliferation; Humans; Neoplasms; Proto-Oncogene Proteins c-akt; Signal Transduction
PubMed: 35462471
DOI: 10.33594/000000512 -
Cureus Mar 2022Erythropoietic protoporphyria is a rare skin condition that commonly presents in childhood. We report a case of a 35-year-old Hispanic male with a history of sun...
Erythropoietic protoporphyria is a rare skin condition that commonly presents in childhood. We report a case of a 35-year-old Hispanic male with a history of sun sensitivity, presenting with complaints of immediate burning and itching of the skin on his face and upper extremities upon sun exposure. On examination, there was minimal face erythema and calluses over the knuckles. Laboratory workup demonstrated substantially increased protoporphyrin (over 10 times the upper limit of normal) along with elevated liver enzyme levels. Liver biopsy confirmed stage 4 cirrhosis. Our patient's cutaneous manifestations were the primary complaint that led to the diagnosis of his terminal hepatic illness. We recommend screening for erythropoietic protoporphyria in patients who present with a life-long history of non-blistering, burning and itching of the skin, which begins immediately upon sun exposure.
PubMed: 35449677
DOI: 10.7759/cureus.23253 -
Scientific Reports Apr 2022Liver damage affects the prognosis of patients with erythropoietic protoporphyria (EPP). However, there is no radical cure for EPP patients with severe liver damage....
Liver damage affects the prognosis of patients with erythropoietic protoporphyria (EPP). However, there is no radical cure for EPP patients with severe liver damage. This study aims to investigate the effectiveness of phlebotomy in patients with severe liver damage. We examined seven patients diagnosed with EPP and liver damage between 2010 and 2020. Of the 7 cases, phlebotomy was performed in 3 cases with severe hepatic disorder, and the improvement effect of hepatic disorder was observed in all cases. In addition, as an additional study, we also investigated the mechanism by which liver damage becomes more severe. Liver biopsy samples were stained with hematoxylin and eosin and immunohistochemistry was used to examine the expression of adenosine triphosphate-binding transporter G2 (ABCG2). Liver biopsies were performed in 3 of 7 patients with EPP. Of these three patients, ABCG2 expression was low in two patients, especially in the protoporphyrin (PP) deposition area. Two patients with reduced ABCG2 expression subsequently developed severe liver damage. However, the causal relationship between the decreased expression of ABCG2 and the exacerbation of liver damage has not been directly proved, and further investigation is required in the future. This study demonstrated the effectiveness of phlebotomy in EPP patients with severe liver damage.
Topics: Ferrochelatase; Humans; Liver; Phlebotomy; Porphyria, Erythropoietic
PubMed: 35414164
DOI: 10.1038/s41598-022-10089-z -
Frontiers in Physiology 2022Partial deficiency of the last enzyme of the heme biosynthetic pathway, namely, ferrochelatase (FECH), is responsible for erythropoietic protoporphyria (EPP) in humans....
Partial deficiency of the last enzyme of the heme biosynthetic pathway, namely, ferrochelatase (FECH), is responsible for erythropoietic protoporphyria (EPP) in humans. This disorder is characterized by painful skin photosensitivity, due to excessive protoporphyrin IX (PPIX) production in erythrocytes. Although several papers report the presence of iron deficiency anemia in about 50% of EPP patients, there is still no a conclusive explanation of the why this occurs. In the present work, we explored hematological indices and iron status in 20 unrelated Italian EPP patients in order to propose a new hypothesis. Our data show that microcytosis is present in EPP patients also in the absence of anemia and iron deficiency with a link between PPIX accumulation and reduced MCV, probably indicating an indirect condition of heme deficiency. Patients studied had a downward shift of iron parameters due to increased hepcidin concentrations only in a state of repleted iron stores. Interestingly, hemoglobin synthesis was not limited by iron supply except in cases with further iron loss, in which concomitantly increased soluble transferrin (Tf) receptor (sTfR) levels were detected. The mechanisms involved in the iron uptake downregulation in EPP remain unclear, and the role of PPIX accumulation in microcytosis.
PubMed: 35309058
DOI: 10.3389/fphys.2022.841050 -
Photodiagnosis and Photodynamic Therapy Jun 2022Erythropoietic protoporphyria (EPP) is caused by deficiency of the enzyme converting protoporphyrin IX (PpIX) into heme resulting in accumulation of PpIX; leading to... (Review)
Review
BACKGROUND
Erythropoietic protoporphyria (EPP) is caused by deficiency of the enzyme converting protoporphyrin IX (PpIX) into heme resulting in accumulation of PpIX; leading to photosensitivity and liver toxicity. Cimetidine might inhibit δ-aminolevulinic acid synthase influencing the heme biosynthesis. We present cases with EPP treated with cimetidine at our department, and a literature review.
METHODS
Systematic searches were performed to identify literature describing EPP patients treated with cimetidine. On that ground we treated EPP patients with cimetidine through spring and summer in 2020 and 2021 at our department. Their erythrocyte PpIX level and standard blood and liver parameters were collected before and during 4 months of treatment. Using a questionnaire, patients were asked about change in photosensitivity, side effects, and whether they would like to resume treatment in the spring of 2022.
RESULTS
Literature searches identified 9 patients treated with cimetidine. Four were outpatients reporting decreased photosensitivity. At our department 18 outpatients started treatment. Fifteen used oral cimetidine daily for 4 months or more providing a significant decrease in erythrocyte PpIX with a median of 20% (range: -18% to 53%) after 4 months. Eleven of the 15 patients reported a decrease in photosensitivity during treatment, 3 patients were unsure, and 1 patient experienced unchanged photosensitivity. Only mild side effects were reported. Fourteen patients requested to resume treatment in the spring of 2022.
CONCLUSIONS
These cases suggest that cimetidine can lower erythrocyte PpIX in patients with EPP.
Topics: Cimetidine; Ferrochelatase; Heme; Humans; Photochemotherapy; Photosensitivity Disorders; Protoporphyria, Erythropoietic; Protoporphyrins
PubMed: 35245673
DOI: 10.1016/j.pdpdt.2022.102793