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Authors = Rossitza Konakchieva ORCID = 0000-0001-7981-4506

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33 pages, 1219 KiB  
Review
Circadian Clock Deregulation and Metabolic Reprogramming: A System Biology Approach to Tissue-Specific Redox Signaling and Disease Development
by Rossitza Konakchieva, Mitko Mladenov, Marina Konaktchieva, Iliyana Sazdova, Hristo Gagov and Georgi Nikolaev
Int. J. Mol. Sci. 2025, 26(13), 6267; https://doi.org/10.3390/ijms26136267 - 28 Jun 2025
Viewed by 937
Abstract
Circadian rhythms govern cellular metabolism, redox balance, and endocrine signaling in numerous tissues. However, chronic disturbance of these biological rhythms, mediated by modern lifestyle factors including shift work, sleep irregularity, and prolonged light exposure, has been increasingly associated with oxidative stress, metabolic dysregulation, [...] Read more.
Circadian rhythms govern cellular metabolism, redox balance, and endocrine signaling in numerous tissues. However, chronic disturbance of these biological rhythms, mediated by modern lifestyle factors including shift work, sleep irregularity, and prolonged light exposure, has been increasingly associated with oxidative stress, metabolic dysregulation, and the pathogenesis of chronic diseases. This review discusses recent mechanistic advances that link circadian misalignment with tissue-specific metabolic reprogramming and impaired proteostasis, focusing on metabolic inflammation and associated pathologies. Emerging work reveals a close interdependence between the circadian clock and proteasome-mediated protein turnover and highlights this interplay’s importance in maintaining redox homeostasis. Furthermore, circadian modulation of the activity of the inflammasome complex is suggested to represent an important, but largely unexplored, risk factor in the pathobiology of both malignancy and metabolic syndrome. Recently, researchers have proposed them as novel endocrine regulators of systemic energy balance and inflammation, with a focus on their circadian regulation. In addition, the emerging domains of chrono-epigenetics and tissue-specific programming of the clock pathways may serve to usher in novel therapies through precision medicine. Moving ahead, circadian-based therapeutic approaches, including time-restricted feeding, chronopharmacology, and metabolic rewiring, have high potential for re-establishing physiological domain homeostasis linked to metabolic inflammation pathologies. Elucidating this reciprocal relationship between circadian biology and cellular stress pathways may one day facilitate the generation of precise interventions aiming to alleviate the health burden associated with circadian disruption. Full article
(This article belongs to the Special Issue Hormone Metabolism and Signaling in Human Health and Disease)
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28 pages, 7141 KiB  
Review
The Role of Reductive Stress in the Pathogenesis of Endocrine-Related Metabolic Diseases and Cancer
by Mitko Mladenov, Iliyana Sazdova, Nikola Hadzi-Petrushev, Rossitza Konakchieva and Hristo Gagov
Int. J. Mol. Sci. 2025, 26(5), 1910; https://doi.org/10.3390/ijms26051910 - 23 Feb 2025
Cited by 2 | Viewed by 1815
Abstract
Reductive stress (RS), characterized by excessive accumulation of reducing equivalents such as NADH and NADPH, is emerging as a key factor in metabolic disorders and cancer. While oxidative stress (OS) has been widely studied, RS and its complex interplay with endocrine regulation remain [...] Read more.
Reductive stress (RS), characterized by excessive accumulation of reducing equivalents such as NADH and NADPH, is emerging as a key factor in metabolic disorders and cancer. While oxidative stress (OS) has been widely studied, RS and its complex interplay with endocrine regulation remain less understood. This review explores molecular circuits of bidirectional crosstalk between metabolic hormones and RS, focusing on their role in diabetes, obesity, cardiovascular diseases, and cancer. RS disrupts insulin secretion and signaling, exacerbates metabolic inflammation, and contributes to adipose tissue dysfunction, ultimately promoting insulin resistance. In cardiovascular diseases, RS alters vascular smooth muscle cell function and myocardial metabolism, influencing ischemia-reperfusion injury outcomes. In cancer, RS plays a dual role: it enhances tumor survival by buffering OS and promoting metabolic reprogramming, yet excessive RS can trigger proteotoxicity and mitochondrial dysfunction, leading to apoptosis. Recent studies have identified RS-targeting strategies, including redox-modulating therapies, nanomedicine, and drug repurposing, offering potential for novel treatments. However, challenges remain, particularly in distinguishing physiological RS from pathological conditions and in overcoming therapy-induced resistance. Future research should focus on developing selective RS biomarkers, optimizing therapeutic interventions, and exploring the role of RS in immune and endocrine regulation. Full article
(This article belongs to the Section Molecular Oncology)
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12 pages, 2919 KiB  
Article
Ikaros Deletions among Bulgarian Patients with Acute Lymphoblastic Leukemia/Lymphoma
by Stefan Lozenov, Yoanna Tsoneva, Georgi Nikolaev and Rossitza Konakchieva
Diagnostics 2024, 14(17), 1953; https://doi.org/10.3390/diagnostics14171953 - 3 Sep 2024
Viewed by 1307
Abstract
The Ikaros zinc finger factor 1 is a transcription factor with a well-known role in B- and T-cell development. The deletions of IKZF1 have an established significance in acute lymphoblastic leukemia, while reports on its prevalence and prognostic significance among ALL subtypes and [...] Read more.
The Ikaros zinc finger factor 1 is a transcription factor with a well-known role in B- and T-cell development. The deletions of IKZF1 have an established significance in acute lymphoblastic leukemia, while reports on its prevalence and prognostic significance among ALL subtypes and regions vary. Breakpoint-specific qPCR is a practical method for testing of the most frequent types of IKZF1 deletions, considering there is clustering of the deletion events. The most commonly reported deletions are Δ4–7, Δ4–8, Δ2–7, and Δ2–8, with deletion Δ4–7 being the most common one. We retrospectively administered a breakpoint-specific qPCR design for screening for the most frequent types of IKZF1 deletions to 78 ALL patients that were diagnosed and treated between 2010 and 2022. We observed the products through gel electrophoresis, and we conducted descriptive statistics, EFS, and OS analyses. Our study found 19 patients with IKZF1 deletions, with two subjects manifesting more than one deletion. The prevalence in the different subgroups was as follows: Ph/+/ B-ALL 46%, Ph/−/ B-ALL 30%, T-ALL/LBL 4%. There was a statistically significant difference in EFS of 39 vs. 0% in favor of patients without deletions (p = 0.000), which translated to a difference in OS of 49 vs. 0% (p = 0.001). This difference was preserved in the subgroup of Ph/−/ B-ALL, while there was no significant difference in the Ph/+/ B-ALL. The most frequently observed type of deletion (15 out of 19) was the Δ4–7. There is a strong negative prognostic impact of the IKZF1 deletions at diagnosis in the observed population. IKZF1 deletion testing through breakpoint-specific qPCR is a practical approach in diagnostic testing for this risk factor. IKZF1 deletions may warrant treatment decisions and intensified treatment strategies to overcome the negative prognostic impact. Full article
(This article belongs to the Special Issue Diagnosis, Prognosis and Management of Hematologic Malignancies)
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29 pages, 4793 KiB  
Review
Oxidative Stress, Reductive Stress and Antioxidants in Vascular Pathogenesis and Aging
by Mitko Mladenov, Lubomir Lubomirov, Olaf Grisk, Dimiter Avtanski, Vadim Mitrokhin, Iliyana Sazdova, Milena Keremidarska-Markova, Yana Danailova, Georgi Nikolaev, Rossitza Konakchieva and Hristo Gagov
Antioxidants 2023, 12(5), 1126; https://doi.org/10.3390/antiox12051126 - 19 May 2023
Cited by 38 | Viewed by 10808
Abstract
This review is focused on the mechanisms that regulate health, disease and aging redox status, the signal pathways that counteract oxidative and reductive stress, the role of food components and additives with antioxidant properties (curcumin, polyphenols, vitamins, carotenoids, flavonoids, etc.), and the role [...] Read more.
This review is focused on the mechanisms that regulate health, disease and aging redox status, the signal pathways that counteract oxidative and reductive stress, the role of food components and additives with antioxidant properties (curcumin, polyphenols, vitamins, carotenoids, flavonoids, etc.), and the role of the hormones irisin and melatonin in the redox homeostasis of animal and human cells. The correlations between the deviation from optimal redox conditions and inflammation, allergic, aging and autoimmune responses are discussed. Special attention is given to the vascular system, kidney, liver and brain oxidative stress processes. The role of hydrogen peroxide as an intracellular and paracrine signal molecule is also reviewed. The cyanotoxins β-N-methylamino-l-alanine (BMAA), cylindrospermopsin, microcystins and nodularins are introduced as potentially dangerous food and environment pro-oxidants. Full article
(This article belongs to the Special Issue Oxidative Stress in Cardiorenal System)
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23 pages, 893 KiB  
Review
Nutritional Management of Thyroiditis of Hashimoto
by Yana Danailova, Tsvetelina Velikova, Georgi Nikolaev, Zorka Mitova, Alexander Shinkov, Hristo Gagov and Rossitza Konakchieva
Int. J. Mol. Sci. 2022, 23(9), 5144; https://doi.org/10.3390/ijms23095144 - 5 May 2022
Cited by 40 | Viewed by 33721
Abstract
Since the thyroid gland is one of the organs most affected by autoimmune processes, many patients with thyroiditis of Hashimoto (TH) seek medical advice on lifestyle variance and dietary modifications to improve and maintain their hyroid function. In this review, we aim to [...] Read more.
Since the thyroid gland is one of the organs most affected by autoimmune processes, many patients with thyroiditis of Hashimoto (TH) seek medical advice on lifestyle variance and dietary modifications to improve and maintain their hyroid function. In this review, we aim to present and discuss some challenges associated with the nutritional management of TH, focusing on environmental and dietary deficits, inflammatory and toxic nutrients, cyanotoxins, etc. We discuss the relationships among different diets, chronic inflammation, and microbiota, and their impact on the development and exacerbation of TH in detail. We share some novel insights into the role of vitamin D and melatonin for preserving thyroid function during chronic inflammation in autoimmune predisposed subjects. A comprehensive overview is provided on anti-inflammatory nutrients and ecological diets, including foods for cleansing and detoxification, which represent strategies to prevent relapses and achieve overall improvement of life quality. In conclusion, data from biomedical and clinical studies provide evidence that an appropriate dietary and lighting regimen could significantly improve the function of the thyroid gland and reduce the reactivity of autoantibodies in TH. Compliance with nutritional guidelines may help TH patients to reduce the need for medicines. Full article
(This article belongs to the Special Issue Immunophenotyping in Autoimmune Diseases and Cancer 2.0)
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36 pages, 1239 KiB  
Review
Membrane Melatonin Receptors Activated Cell Signaling in Physiology and Disease
by Georgi Nikolaev, Ralitsa Robeva and Rossitza Konakchieva
Int. J. Mol. Sci. 2022, 23(1), 471; https://doi.org/10.3390/ijms23010471 - 31 Dec 2021
Cited by 59 | Viewed by 11547
Abstract
The pineal hormone melatonin has attracted great scientific interest since its discovery in 1958. Despite the enormous number of basic and clinical studies the exact role of melatonin in respect to human physiology remains elusive. In humans, two high-affinity receptors for melatonin, MT1 [...] Read more.
The pineal hormone melatonin has attracted great scientific interest since its discovery in 1958. Despite the enormous number of basic and clinical studies the exact role of melatonin in respect to human physiology remains elusive. In humans, two high-affinity receptors for melatonin, MT1 and MT2, belonging to the family of G protein-coupled receptors (GPCRs) have been cloned and identified. The two receptor types activate Gi proteins and MT2 couples additionally to Gq proteins to modulate intracellular events. The individual effects of MT1 and MT2 receptor activation in a variety of cells are complemented by their ability to form homo- and heterodimers, the functional relevance of which is yet to be confirmed. Recently, several melatonin receptor genetic polymorphisms were discovered and implicated in pathology—for instance in type 2 diabetes, autoimmune disease, and cancer. The circadian patterns of melatonin secretion, its pleiotropic effects depending on cell type and condition, and the already demonstrated cross-talks of melatonin receptors with other signal transduction pathways further contribute to the perplexity of research on the role of the pineal hormone in humans. In this review we try to summarize the current knowledge on the membrane melatonin receptor activated cell signaling in physiology and pathology and their relevance to certain disease conditions including cancer. Full article
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