Quantification and characterization of grouped type I myofibers in human aging

Neil A. Kelly; Kelley G. Hammond; Michael J. Stec; C. Scott Bickel; Samuel T. Windham; S. Craig Tuggle; Marcas M. Bamman

doi:10.1002/mus.25711

Quantification and characterization of grouped type I myofibers in human aging

Neil A. Kelly, Kelley G. Hammond, Michael J. Stec, C. Scott Bickel, Samuel T. Windham, S. Craig Tuggle, Marcas M. Bamman

Research output: Contribution to journal › Article › peer-review

18 Scopus citations

Abstract

Introduction: Myofiber type grouping is a histological hallmark of age-related motor unit remodeling. Despite the accepted concept that denervation–reinnervation events lead to myofiber type grouping, the completeness of those conversions remains unknown. Methods: Type I myofiber grouping was assessed in vastus lateralis biopsies from Young (26 ± 4 years; n = 27) and Older (66 ± 4 years; n = 91) adults. Grouped and ungrouped type I myofibers were evaluated for phenotypic differences. Results: Higher type I grouping in Older versus Young was driven by more myofibers per group (i.e., larger group size) (P < 0.05). In Older only, grouped type I myofibers displayed larger cross-sectional area, more myonuclei, lower capillary supply, and more sarco(endo)plasmic reticulum calcium ATPase I (SERCA I) expression (P < 0.05) than ungrouped type I myofibers. Discussion: Grouped type I myofibers retain type II characteristics suggesting that conversion during denervation–reinnervation events is either progressive or incomplete. Muscle Nerve 57: E52–E59, 2018.

Original language	English (US)
Pages (from-to)	E52-E59
Journal	Muscle and Nerve
Volume	57
Issue number	1
DOIs	https://doi.org/10.1002/mus.25711
State	Published - Jan 2018
Externally published	Yes

All Science Journal Classification (ASJC) codes

Physiology
Clinical Neurology
Cellular and Molecular Neuroscience
Physiology (medical)

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10.1002/mus.25711

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@article{f52bf5bf69ac49998a9f4be44cf72cce,

title = "Quantification and characterization of grouped type I myofibers in human aging",

abstract = "Introduction: Myofiber type grouping is a histological hallmark of age-related motor unit remodeling. Despite the accepted concept that denervation–reinnervation events lead to myofiber type grouping, the completeness of those conversions remains unknown. Methods: Type I myofiber grouping was assessed in vastus lateralis biopsies from Young (26 ± 4 years; n = 27) and Older (66 ± 4 years; n = 91) adults. Grouped and ungrouped type I myofibers were evaluated for phenotypic differences. Results: Higher type I grouping in Older versus Young was driven by more myofibers per group (i.e., larger group size) (P < 0.05). In Older only, grouped type I myofibers displayed larger cross-sectional area, more myonuclei, lower capillary supply, and more sarco(endo)plasmic reticulum calcium ATPase I (SERCA I) expression (P < 0.05) than ungrouped type I myofibers. Discussion: Grouped type I myofibers retain type II characteristics suggesting that conversion during denervation–reinnervation events is either progressive or incomplete. Muscle Nerve 57: E52–E59, 2018.",

author = "Kelly, {Neil A.} and Hammond, {Kelley G.} and Stec, {Michael J.} and Bickel, {C. Scott} and Windham, {Samuel T.} and Tuggle, {S. Craig} and Bamman, {Marcas M.}",

note = "Funding Information: Additional supporting information may be found in the online version of this article Abbreviations: Ab, antibody; CSA, cross-sectional area; GAM, goat-anti-mouse; MHC, myosin heavy chain; PAX7, paired box 7; SERCA, sarco(endo)plasmic reticulum calcium ATPase; UEA-I, Ulex europaeus agglutinin; PBS, phosphate-buffered saline; RT, resistance exercise training Key words: denervation; motor unit; myofiber type grouping; myofiber switching; reinnervation Funding: This work was supported in part by National Institutes of Health grants R01AG017896, T32HD071866, P2CHD086851, R01AG046920, R01HD084124, and UL1TR001417. We are indebted to the research participants for their effort and dedication. Publisher Copyright: {\textcopyright} 2017 Wiley Periodicals, Inc.",

year = "2018",

month = jan,

doi = "10.1002/mus.25711",

language = "English (US)",

volume = "57",

pages = "E52--E59",

journal = "Muscle and Nerve",

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TY - JOUR

T1 - Quantification and characterization of grouped type I myofibers in human aging

AU - Kelly, Neil A.

AU - Hammond, Kelley G.

AU - Stec, Michael J.

AU - Bickel, C. Scott

AU - Windham, Samuel T.

AU - Tuggle, S. Craig

AU - Bamman, Marcas M.

N1 - Funding Information: Additional supporting information may be found in the online version of this article Abbreviations: Ab, antibody; CSA, cross-sectional area; GAM, goat-anti-mouse; MHC, myosin heavy chain; PAX7, paired box 7; SERCA, sarco(endo)plasmic reticulum calcium ATPase; UEA-I, Ulex europaeus agglutinin; PBS, phosphate-buffered saline; RT, resistance exercise training Key words: denervation; motor unit; myofiber type grouping; myofiber switching; reinnervation Funding: This work was supported in part by National Institutes of Health grants R01AG017896, T32HD071866, P2CHD086851, R01AG046920, R01HD084124, and UL1TR001417. We are indebted to the research participants for their effort and dedication. Publisher Copyright: © 2017 Wiley Periodicals, Inc.

PY - 2018/1

Y1 - 2018/1

N2 - Introduction: Myofiber type grouping is a histological hallmark of age-related motor unit remodeling. Despite the accepted concept that denervation–reinnervation events lead to myofiber type grouping, the completeness of those conversions remains unknown. Methods: Type I myofiber grouping was assessed in vastus lateralis biopsies from Young (26 ± 4 years; n = 27) and Older (66 ± 4 years; n = 91) adults. Grouped and ungrouped type I myofibers were evaluated for phenotypic differences. Results: Higher type I grouping in Older versus Young was driven by more myofibers per group (i.e., larger group size) (P < 0.05). In Older only, grouped type I myofibers displayed larger cross-sectional area, more myonuclei, lower capillary supply, and more sarco(endo)plasmic reticulum calcium ATPase I (SERCA I) expression (P < 0.05) than ungrouped type I myofibers. Discussion: Grouped type I myofibers retain type II characteristics suggesting that conversion during denervation–reinnervation events is either progressive or incomplete. Muscle Nerve 57: E52–E59, 2018.

AB - Introduction: Myofiber type grouping is a histological hallmark of age-related motor unit remodeling. Despite the accepted concept that denervation–reinnervation events lead to myofiber type grouping, the completeness of those conversions remains unknown. Methods: Type I myofiber grouping was assessed in vastus lateralis biopsies from Young (26 ± 4 years; n = 27) and Older (66 ± 4 years; n = 91) adults. Grouped and ungrouped type I myofibers were evaluated for phenotypic differences. Results: Higher type I grouping in Older versus Young was driven by more myofibers per group (i.e., larger group size) (P < 0.05). In Older only, grouped type I myofibers displayed larger cross-sectional area, more myonuclei, lower capillary supply, and more sarco(endo)plasmic reticulum calcium ATPase I (SERCA I) expression (P < 0.05) than ungrouped type I myofibers. Discussion: Grouped type I myofibers retain type II characteristics suggesting that conversion during denervation–reinnervation events is either progressive or incomplete. Muscle Nerve 57: E52–E59, 2018.

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ER -

Quantification and characterization of grouped type I myofibers in human aging

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