Schwann cells as a source of insulin‐like growth factor‐1 for extraocular muscles

Feng, Cheng‐Yuan; Bartheld, Christopher S. von

doi:10.1002/mus.21519

Cited by 8 publications

(10 citation statements)

References 64 publications

(84 reference statements)

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“…Indeed, some growth factors, trophic factors, and cytokines can be transported anterogradely in nerves, including motor nerves [65, 67]. Our recent study on IGF1 showed that this growth factor is prominently expressed by Schwann cells in oculomotor nerves, and IGF1 protein can be transported from the nerve to EOMs [21]. Nevertheless, our current study shows that the EOMs per se express much more IGF1, CT1, and GDNF than limb skeletal muscles.…”

Section: Discussionmentioning

confidence: 68%

“…GoTaq green master mix (Promega, Madison, WI, USA) was used for qualitative PCR. “RT minus” control was used to detect possible genomic DNA contamination, as described previously [21]. …”

Section: Methodsmentioning

confidence: 99%

“…The best primer pairs (lowest Ct, highest amplification efficiency, and stable performance) were selected for real-time PCR. The following sequences were obtained from published reports: chicken primer sequences for IGF1 and GAPDH [21], rat primer sequences for IGF-1A, GAPDH [10], CT1, IGF1 receptor [58], and gp130. LIF receptor forward primer was 5′-TCATCAGTGTGGTGGCAAGAA-3′ and reverse primer 5′-GCAGGGCTC AGACCATGACG-3′.…”

Section: Methodsmentioning

confidence: 99%

“…Expression stability of GAPDH (geNorm software, M value=0.563) was comparable with ribosomal proteins ( M values=0.459 and 0.497, respectively), and more stable than elongation factors 1A 1 and 1A 2 ( M values of 0.668 and 0.919, respectively). We used GAPDH as our housekeeping gene since GAPDH is most commonly used in EOM gene expression studies [10, 21, 22]. …”

Section: Methodsmentioning

confidence: 99%

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How to make rapid eye movements “rapid”: the role of growth factors for muscle contractile properties

Feng

Bartheld

2011

Pflugers Arch - Eur J Physiol

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Different muscle functions require different muscle contraction properties. Saccade-generating extraocular muscles (EOMs) are the fastest muscles in the human body, significantly faster than limb skeletal muscles. Muscle contraction speed is subjected to plasticity, i.e., contraction speed can be adjusted to serve different demands, but little is known about the molecular mechanisms that control contraction speed. Therefore, we examined whether myogenic growth factors modulate contractile properties, including twitch contraction time (onset of force to peak force) and half relaxation time (peak force to half relaxation). We examined effects of three musclederived growth factors: insulin-like growth factor 1 (IGF1), cardiotrophin-1 (CT1), and glial cell line-derived neurotrophic factor (GDNF). In gain-of-function experiments, CT1 or GDNF injected into the orbit shortened contraction time, and IGF1 or CT1 shortened half relaxation time. In lossof-function experiments with binding proteins or neutralizing antibodies, elimination of endogenous IGFs prolonged both contraction time and half relaxation time, while eliminating endogenous GDNF prolonged contraction time, with no effect on half relaxation time. Elimination of endogenous IGFs or CT1, but not GDNF, significantly reduced contractile force. Thus, IGF1, CT1, and GDNF have partially overlapping but not identical effects on muscle contractile properties. Expression of these three growth factors was measured in chicken and/or rat EOMs by real-time PCR. The "fast" EOMs express significantly more message encoding these growth factors and their receptors than skeletal muscles with slower contractile properties. Taken together, these findings indicate that EOM contractile kinetics is regulated by the amount of myogenic growth factors available to the muscle.

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Section: Discussionmentioning

confidence: 68%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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How to make rapid eye movements “rapid”: the role of growth factors for muscle contractile properties

Feng

Bartheld

2011

Pflugers Arch - Eur J Physiol

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“…In our experiments, geNorm ranked GAPDH as one of the two most stably expressed genes (GAPDH and EF1A2). We chose GAPDH as the reference gene for two reasons: because of its stable expression and its use for quantifying skeletal muscle IGF-1 expression in previous studies, thus making our data comparable with those generated in other labs (Cheema et al, 2005; Fischer et al, 2005; Heinemeier et al, 2007; Feng and von Bartheld, 2010; Li et al, 2011). The amplification efficiencies of all primers were within 90%–110%.…”

Section: Resultsmentioning

confidence: 99%

Expression of insulin-like growth factor 1 isoforms in the rabbit oculomotor system

Feng

Bartheld

2011

Growth Hormone & IGF Research

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Objective The insulin-like growth factor-1 (IGF-1) gene encodes two isoforms, IGF-1Ea and IGF-1Eb. Both isoforms can regulate skeletal muscle growth and strength. It has been suggested that IGF-Eb may be more potent in promoting skeletal muscle hypertrophy. Precise contractile force regulation is particularly important in the oculomotor system. However, expression of these isoforms in mammalian extraocular muscles (EOMs) is unknown. Here, we examined their expression in rabbit EOMs and the innervating nerve, two potential sources for myogenic growth factors, and compared isoform expression between EOMs and limb skeletal muscles. Design Expression of IGF-1 isoforms was quantified by real-time RT-PCR in adult rabbit EOMs, trochlear and ophthalmic nerves, and compared with expression in rabbit limb skeletal muscles. The presence of mature IGF-1 peptide in the muscles was further examined by Western blot. Results Both IGF-1Ea and IGF-1Eb were expressed in the EOM and the trochlear nerve. Both isoforms were expressed at significantly higher levels (9- fold) in EOM than in limb skeletal muscle. Transcripts of IGF-1 isoforms, of IGF-1 receptor and of IGF binding proteins showed a gradient distribution along the EOM from proximal to distal. The mature IGF-1 protein showed the same gradient distribution in the EOM. Conclusions Expression of relatively abundant amounts of both IGF-1 splicing isoforms in EOMs, and at a significantly higher level than in limb skeletal muscle, underscores the potential relevance of these myogenic growth factors in EOM plasticity and force regulation.

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Insulin‐Like Growth Factor I Regulation and Its Actions in Skeletal Muscle

Vassilakos

Barton

2018

Comprehensive Physiology

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The insulin‐like growth factor (IGF) pathway is essential for promoting growth and survival of virtually all tissues. It bears high homology to its related protein insulin, and as such, there is an interplay between these molecules with regard to their anabolic and metabolic functions. Skeletal muscle produces a significant proportion of IGF‐1, and is highly responsive to its actions, including increased muscle mass and improved regenerative capacity. In this overview, the regulation of IGF‐1 production, stability, and activity in skeletal muscle will be described. Second, the physiological significance of the forms of IGF‐1 produced will be discussed. Last, the interaction of IGF‐1 with other pathways will be addressed. © 2019 American Physiological Society. Compr Physiol 9:413‐438, 2019.

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Schwann cells as a source of insulin‐like growth factor‐1 for extraocular muscles

Cited by 8 publications

References 64 publications

How to make rapid eye movements “rapid”: the role of growth factors for muscle contractile properties

How to make rapid eye movements “rapid”: the role of growth factors for muscle contractile properties

Expression of insulin-like growth factor 1 isoforms in the rabbit oculomotor system

Insulin‐Like Growth Factor I Regulation and Its Actions in Skeletal Muscle

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