p21<sup>Cip1</sup> expression is increased in ambient oxygen, compared to estimated physiological (5%) levels in rat muscle precursor cell culture

Lees, Simon J.; Childs, Tom E.; Booth, Frank W.

doi:10.1111/j.1365-2184.2008.00512.x

Cited by 29 publications

(38 citation statements)

References 46 publications

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“…Low, estimated physiological oxygen culture conditions (3-6%) have been shown to enhance the proliferation, differentiation, and viability of primary mouse and rat myoblasts (Lees et al 2008;Chakravarthy et al 2001;Csete et al 2001). Here we report for the first time, that the proliferative capacity of human myoblasts was also enhanced by low oxygen culture conditions, but viability and differentiation of human myoblasts were similar in low and standard oxygen culture conditions.…”

Section: Discussionmentioning

confidence: 98%

“…There was a significant increase in cell number when proliferating myoblasts, obtained from the vastus lateralis muscle of elderly donors, were cultured in 5% compared to 20% oxygen. Although enhanced proliferation of rodent myoblasts in low oxygen culture conditions has been well described in the literature (Lees et al 2008;Csete et al 2001), because of species differences it was not known whether human myoblasts would respond similarly. Proliferation is far more responsive to environmental regulation, such as low oxygen culture conditions, in rodent compared to human cells (Smogorzewska and de Lange 2002;Mouly et al 2006).…”

Section: Discussionmentioning

confidence: 98%

“…At each passage myoblasts were subcultured into new ECM-coated flasks at a density of 3,000 cells/ cm 2 . Myoblasts were initially cultured in 5% oxygen which was defined as the control condition to best represent estimated physiological oxygen levels (Lees et al 2008). The cells in culture were tested regularly for mycoplasma and no contamination was detected.…”

Section: Muscle Satellite Cell Isolation and Culturementioning

confidence: 99%

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Enhanced proliferation of human skeletal muscle precursor cells derived from elderly donors cultured in estimated physiological (5%) oxygen

et al. 2009

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Human skeletal muscle precursor cells (myoblasts) have significant therapeutic potential and are a valuable research tool to study muscle cell biology. Oxygen is a critical factor in the successful culture of myoblasts with low (1-6%) oxygen culture conditions enhancing the proliferation, differentiation, and/or viability of mouse, rat, and bovine myoblasts. The specific effects of low oxygen depend on the myoblast source and oxygen concentration; however, variable oxygen conditions have not been tested in the culture of human myoblasts. In this study, muscle precursor cells were isolated from vastus lateralis muscle biopsies and myoblast cultures were established in 5% oxygen, before being divided into physiological (5%) or standard (20%) oxygen conditions for experimental analysis. Five percent oxygen increased proliferating myoblast numbers, and since low oxygen had no significant effect on myoblast viability, this increase in cell number was attributed to enhanced proliferation. The proportion of cells in the S (DNA synthesis) phase of the cell cycle was increased by 50%, and p21(Cip1) gene and protein expression was decreased in 5 versus 20% oxygen. Unlike in rodent and bovine myoblasts, the increase in myoD, myogenin, creatine kinase, and myosin heavy chain IIa gene expression during differentiation was similar in 5 and 20% oxygen; as was myotube hypertrophy. These data indicate for the first time that low oxygen culture conditions stimulate proliferation, whilst maintaining (but not enhancing) the viability and the differentiation potential of human primary myoblasts and should be considered as optimum conditions for ex-vivo expansion of these cells.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 98%

Section: Muscle Satellite Cell Isolation and Culturementioning

confidence: 99%

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Enhanced proliferation of human skeletal muscle precursor cells derived from elderly donors cultured in estimated physiological (5%) oxygen

et al. 2009

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“…MPC isolation was modified from Allen et al (2) as previously described (24,25). Briefly, cells isolated from the gastrocnemius and plantaris muscles by pronase digestion were preplated for 24 h on tissue culture-treated 150-mm plates.…”

Section: Methodsmentioning

confidence: 99%

“…Kip1 promoter (Ϫ4362/ ϩ0.421 kb) was cloned using the primers previously described (24). The full-length sequence is shown in supplemental Fig.…”

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confidence: 99%

Age-dependent FOXO regulation of p27^Kip1 expression via a conserved binding motif in rat muscle precursor cells

Lees

Childs²,

Booth³

2008

American Journal of Physiology-Cell Physiology

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promoter activity and protein expression, whereas it decreased proliferation in muscle precursor cells (MPCs). The objectives of the present study were to 1) locate and identify FOXO regulatory elements in the rat p27Kip1 promoter using deletion analysis of a promoter/reporter construct and 2) determine if age-related differences exist in FOXO-induced p27Kip1 expression. The full-length (Ϫ4.0/ϩ0.4 kb) rat p27Kip1 promoter construct revealed that both FOXO1 and FOXO3a induced an increase in transcriptional activity. Interestingly, MPCs isolated from old animals exhibited an increased FOXO3a-induced p27Kip1 promoter activity compared with MPCs isolated from young animals. Deletion of a 253-bp portion of the 5Ј-untranslated region (UTR) resulted in a significant decrease in FOXO-induced p27Kip1 promoter expression. Site-specific mutation of a daf-16 family protein-binding element (DBE) within this 253-bp portion of the 5Ј-UTR also demonstrated a decrease in FOXO-induced p27Kip1 promoter expression. These data suggest that a putative FOXO regulatory element located in the 5Ј-UTR of the rat p27 Kip1 gene plays a role in the age-dependent differences in FOXO3a-dependent p27Kip1 promoter expression. These findings have implications for developing treatment strategies aimed at increasing the proliferation of MPCs and regenerative capacity of aged skeletal muscle. satellite cell; skeletal muscle; proliferation; 5Ј-untranslated region; daf-16 family protein-binding element; forkhead box O EMERGING EVIDENCE suggests that forkhead box O (FOXO) transcription factors are at the nexus of aging, metabolism, and cell fate/function (9). The primary regulation of FOXO family proteins is downstream of insulin and IGF signaling. Aktmediated phosphorylation of FOXO results in nuclear exclusion and inhibition of transcriptional activity (7,8,23,30,33). However, despite extensive study into the multitude of functional roles, the details of the regulatory regions for targets of FOXO are still mostly elusive.FOXO proteins play a key role in multiple conditions of skeletal muscle wasting. Several models of skeletal muscle atrophy cause upregulation of the transcripts of the musclespecific ubiquitin ligases muscle ring finger-1 (MuRF-1) and muscle atrophy F-box (MAFbx/atrogin-1) (5). Followup experiments revealed that overexpression of MAFbx induced myotube atrophy in culture, whereas mice lacking either the MuRF-1 or MAFbx genes were resistant to denervation-induced muscle atrophy (5). A mutant FOXO that was constitutively active induced MAFbx expression and caused atrophy in myotubes in culture (34). Moreover, RNA inhibitor knock down of FOXO3a in vivo decreased MAFbx expression (34). Interestingly, recent findings have revealed increased FOXO3a mRNA (32) in sarcopenia, which is defined as an age-associated loss of skeletal muscle mass and strength.

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Characterization and Regulation of Mechanical Loading‐Induced Compensatory Muscle Hypertrophy

Adams

Bamman

2012

Comprehensive Physiology

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In mammalian systems, skeletal muscle exists in a dynamic state that monitors and regulates the physiological investment in muscle size to meet the current level of functional demand. This review attempts to consolidate current knowledge concerning development of the compensatory hypertrophy that occurs in response to a sustained increase in the mechanical loading of skeletal muscle. Topics covered include: defining and measuring compensatory hypertrophy, experimental models, loading stimulus parameters, acute responses to increased loading, hyperplasia, myofiber-type adaptations, the involvement of satellite cells, mRNA translational control, mechanotransduction, and endocrinology. The authors conclude with their impressions of current knowledge gaps in the field that are ripe for future study.

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p21^Cip1 expression is increased in ambient oxygen, compared to estimated physiological (5%) levels in rat muscle precursor cell culture

Cited by 29 publications

References 46 publications

Enhanced proliferation of human skeletal muscle precursor cells derived from elderly donors cultured in estimated physiological (5%) oxygen

Enhanced proliferation of human skeletal muscle precursor cells derived from elderly donors cultured in estimated physiological (5%) oxygen

Age-dependent FOXO regulation of p27^Kip1 expression via a conserved binding motif in rat muscle precursor cells

Characterization and Regulation of Mechanical Loading‐Induced Compensatory Muscle Hypertrophy

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p21Cip1 expression is increased in ambient oxygen, compared to estimated physiological (5%) levels in rat muscle precursor cell culture

Cited by 29 publications

References 46 publications

Enhanced proliferation of human skeletal muscle precursor cells derived from elderly donors cultured in estimated physiological (5%) oxygen

Enhanced proliferation of human skeletal muscle precursor cells derived from elderly donors cultured in estimated physiological (5%) oxygen

Age-dependent FOXO regulation of p27Kip1 expression via a conserved binding motif in rat muscle precursor cells

Characterization and Regulation of Mechanical Loading‐Induced Compensatory Muscle Hypertrophy

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p21^Cip1 expression is increased in ambient oxygen, compared to estimated physiological (5%) levels in rat muscle precursor cell culture

Age-dependent FOXO regulation of p27^Kip1 expression via a conserved binding motif in rat muscle precursor cells