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Portillo AM, Varela E, García-Velasco JA. Influence of telomerase activity and initial distribution on human follicular aging: Moving from a discrete to a continuum model. Math Biosci 2023; 358:108985. [PMID: 36828232 DOI: 10.1016/j.mbs.2023.108985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 02/15/2023] [Accepted: 02/15/2023] [Indexed: 02/24/2023]
Abstract
A discrete model is proposed for the temporal evolution of a population of cells sorted according to their telomeric length. This model assumes that, during cell division, the distribution of the genetic material to daughter cells is asymmetric, i.e. chromosomes of one daughter cell have the same telomere length as the mother, while in the other daughter cell telomeres are shorter. Telomerase activity and cell death are also taken into account. The continuous model is derived from the discrete model by introducing the generational age as a continuous variable in [0,h], being h the Hayflick limit, i.e. the number of times that a cell can divide before reaching the senescent state. A partial differential equation with boundary conditions is obtained. The solution to this equation depends on the initial telomere length distribution. The initial and boundary value problem is solved exactly when the initial distribution is of exponential type. For other types of initial distributions, a numerical solution is proposed. The model is applied to the human follicular growth from preantral to preovulatory follicle as a case study and the aging rate is studied as a function of telomerase activity, the initial distribution and the Hayflick limit. Young, middle and old cell-aged initial normal distributions are considered. In all cases, when telomerase activity decreases, the population ages and the smaller the h value, the higher the aging rate becomes. However, the influence of these two parameters is different depending on the initial distribution. In conclusion, the worst-case scenario corresponds to an aged initial telomere distribution.
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Affiliation(s)
- A M Portillo
- Instituto de Investigación en Matemáticas de la Universidad de Valladolid, Valladolid, Spain; Departamento de Matemática Aplicada, Escuela de Ingenierías Industriales, Universidad de Valladolid, Pso. Prado de la Magdalena 3-5, Valladolid, 47011, Spain.
| | - E Varela
- IVI Foundation, The Health Research Institute La Fe (IIS La Fe), Edificio Biopolo. Av. Fernando Abril Martorell, 106 - Torre A, Planta 1, Valencia, 46026, Spain; Rey Juan Carlos University, Edificio Departamental II. Av. de Atenas, s/n, Alcorcón, Madrid, 28922, Spain.
| | - J A García-Velasco
- IVI Foundation, The Health Research Institute La Fe (IIS La Fe), Edificio Biopolo. Av. Fernando Abril Martorell, 106 - Torre A, Planta 1, Valencia, 46026, Spain; IVIRMA Madrid, Av. del Talgo, 68, Madrid, 28023, Spain; Rey Juan Carlos University, Edificio Departamental II. Av. de Atenas, s/n, Alcorcón, Madrid, 28922, Spain.
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Kazantseva AV, Davydova YD, Enikeeva RF, Mustafin RN, Lobaskova MM, Malykh SB, Khusnutdinova EK. Individual Differences in Relative Telomere Length in Mentally Healthy Subjects: The Effect of TERT Gene Polymorphism and Urban Residency. RUSS J GENET+ 2022; 58:1135-1144. [PMID: 36119151 PMCID: PMC9470233 DOI: 10.1134/s1022795422090101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/17/2022] [Accepted: 04/04/2022] [Indexed: 11/23/2022]
Abstract
The changes in the telomere length caused by the terminal underreplication in the existing literature are related to depressive disorders. However, the use of the telomere length as a biomarker of depressive states is ambiguous, which is due to the effect of various environmental factors on both the psychoemotional state and cellular aging of an organism. In order to identify the possible use of the relative telomere length (RTL) measured in peripheral blood leukocytes as a biomarker of enhanced liability to depression prior to the clinical symptoms, as well as to determine the link between telomere length, sociodemographic factors, allelic variants of the genes involved in the regulation of telomere elongation, and depression level, the association analysis of reverse transcriptase (TERT rs7726159), telomerase RNA component (TERC rs1317082), and the CST complex encoding protein (OBFC1 rs2487999) gene polymorphisms was performed with RTL and depression level in mentally healthy individuals (N = 1065) aged 18-25 years. Together with genetic variants, the examined regression models included various sociodemographic parameters as predictors. As a result of statistical analysis, we failed to observe the association between RTL and individual differences in depression level in the studied sample. Nevertheless, multiple regression analysis allowed us to construct a statistically significant model of individual variance in RTL (P = 4.3е-4; r 2 = 0.018), which included rs7726159 in the TERT gene (P = 0.020; β = 0.078) and such environmental predictors as age (P = 0.001; β = -0.027) and place of residence in childhood (urban/rural area) (P = 0.048; β = 0.063). The data obtained confirm the involvement of TERT gene variants and age in telomere length in mentally healthy individuals aged 18-25 years and indicate a negative effect of urban residency on telomere length shortening, which reflects the cellular aging of an organism.
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Affiliation(s)
- A V Kazantseva
- Institute of Biochemistry and Genetics-Subdivision of the Ufa Federal Research Centre, Russian Academy of Sciences, 450054 Ufa, Russia.,Bashkir State University, 450076 Ufa, Russia.,Ufa State Petroleum Technical University, 450064 Ufa, Russia
| | - Yu D Davydova
- Institute of Biochemistry and Genetics-Subdivision of the Ufa Federal Research Centre, Russian Academy of Sciences, 450054 Ufa, Russia.,Bashkir State University, 450076 Ufa, Russia
| | - R F Enikeeva
- Institute of Biochemistry and Genetics-Subdivision of the Ufa Federal Research Centre, Russian Academy of Sciences, 450054 Ufa, Russia.,Bashkir State University, 450076 Ufa, Russia
| | - R N Mustafin
- Bashkir State Medical University, 450008 Ufa, Russia
| | - M M Lobaskova
- Psychological Institute, Russian Academy of Education, 125009 Moscow, Russia
| | - S B Malykh
- Psychological Institute, Russian Academy of Education, 125009 Moscow, Russia.,Moscow State University, 119991 Moscow, Russia
| | - E K Khusnutdinova
- Institute of Biochemistry and Genetics-Subdivision of the Ufa Federal Research Centre, Russian Academy of Sciences, 450054 Ufa, Russia.,Bashkir State University, 450076 Ufa, Russia.,Moscow State University, 119991 Moscow, Russia
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Ovarian Telomerase and Female Fertility. Biomedicines 2021; 9:biomedicines9070842. [PMID: 34356906 PMCID: PMC8301802 DOI: 10.3390/biomedicines9070842] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 07/08/2021] [Accepted: 07/14/2021] [Indexed: 11/16/2022] Open
Abstract
Women's fertility is characterized both quantitatively and qualitatively mainly by the pool of ovarian follicles. Monthly, gonadotropins cause an intense multiplication of granulosa cells surrounding the oocyte. This step of follicular development requires a high proliferation ability for these cells. Telomere length plays a crucial role in the mitotic index of human cells. Hence, disrupting telomere homeostasis could directly affect women's fertility. Strongly expressed in ovaries, telomerase is the most effective factor to limit telomeric attrition and preserve ovarian reserve. Considering these facts, two situations of infertility could be correlated with the length of telomeres and ovarian telomerase activity: PolyCystic Ovary Syndrome (PCOS), which is associated with a high density of small antral follicles, and Premature Ovarian Failure (POF), which is associated with a premature decrease in ovarian reserve. Several authors have studied this topic, expecting to find long telomeres and strong telomerase activity in PCOS and short telomeres and low telomerase activity in POF patients. Although the results of these studies are contradictory, telomere length and the ovarian telomerase impact in women's fertility disorders appear obvious. In this context, our research perspectives aimed to explore the stimulation of ovarian telomerase to limit the decrease in the follicular pool while avoiding an increase in cancer risk.
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