- Open Access
Regulation of murine skeletal muscle growth by STAT5B is age- and sex-specific
© The Author(s). 2019
- Received: 21 February 2019
- Accepted: 11 June 2019
- Published: 24 June 2019
Sexually dimorphic growth has been attributed to the growth hormone (GH)/insulin-like growth factor 1 (IGF1) axis, particularly GH-induced activation of the intracellular signal transducer and activator of transcription 5B (STAT5B), because deletion of STAT5B reduces body mass and the mass of skeletal muscles in male mice to that in female mice. However, it remains unclear why these effects are sex- and species-specific, because the loss of STAT5B retards growth in girls, but not in male mice. Our objectives were to determine whether sexually dimorphic growth of skeletal muscle persisted in STAT5B−/− mice and investigate the mechanisms by which STAT5B regulates sexually dimorphic growth.
Blood and skeletal muscle were harvested from male and female STAT5B−/− mice and their wild-type littermates from the onset of puberty to adulthood.
Growth of the skeleton and skeletal muscles was retarded in both sexes of STAT5B−/− mice, but more so in males. Although reduced, sexually dimorphic growth of skeletal muscle persisted in STAT5B−/− mice with an oxidative shift in the composition of myofibres in both sexes. Concentrations of IGF1 in blood and skeletal muscle were reduced in male STAT5B−/− mice at all ages, but only in female STAT5B−/− mice at the onset of puberty. Expression of androgen receptor (AR) and oestrogen receptor alpha (ERα) mRNA and protein was reduced in skeletal muscles of male and female STAT5B−/− mice, respectively. Loss of STAT5B abolished the sexually dimorphic expression of myostatin protein and Igf1, Ar, Erα, suppressor of cytokine signalling 2 (Socs2), and cytokine-inducible SH2-containing protein (Cis) mRNA in skeletal muscle.
STAT5B appears to mediate GH signalling in skeletal muscles of male mice at all ages, but only until puberty in female mice. STAT5B also appears to mediate the actions of androgens and oestrogens in both male and female mice, but sexually dimorphic growth persists in STAT5B−/− mice.
- Sexually dimorphic growth
Sexually dimorphic growth of skeletal muscle is evident in most mammals from puberty, with males developing a larger body size and muscle mass, with more fast-twitch and less slow-twitch myofibres than females [1, 2]. These differences have been attributed to the actions of the growth hormone (GH)/insulin-like growth factor 1 (IGF1) axis, the major regulator of post-natal growth, because deletion of either the GH receptor (GHR) or IGF1 in mice abolishes the sexual dimorphism of body size [3, 4]. The premise is that GH binds to the GHR, activating the signal transducer and activator of transcription (STAT) family members STAT1, − 3, 5A, and 5B, which form homodimers and heterodimers that regulate the transcription of IGF1 and other target genes . The actions of GH on skeletal muscle appear to be predominantly mediated by STAT5A and STAT5B, because local deletion of STAT5A and STAT5B reduces post-natal muscle growth, while global deletion results in a similar phenotype to the GHR knockout mouse [4, 6]. Of the two, STAT5B appears to be the principle transcription factor regulating sexually dimorphic growth, because removal of STAT5B reduces body mass and the absolute mass of skeletal muscles in male mice to that in female mice [7–9]. The abolition of sexually dimorphic growth in STAT5B−/− mice has been attributed to reduced circulating concentrations of IGF1 and increased concentrations of myostatin in skeletal muscles of only male mice [7–9]. IGF1 and myostatin are the key regulators of skeletal muscle growth, and both are directly regulated by GH via STAT5B . While IGF1 is the major anabolic post-natal growth factor, myostatin restricts the development of skeletal muscle and promotes the development of adipose tissue by inhibiting the signalling of IGF1 [10–12].
However, attributing the sexually dimorphic growth of skeletal muscle to the regulation of IGF1 and myostatin by STAT5B creates important paradoxes. In contrast to mice, it is not clear why inactivating mutations in the Stat5b gene in humans reduce growth and circulating concentrations of IGF1 in both sexes . Similarly, unlike the absence of STAT5B alone, it is unclear why sexually dimorphic growth persists in mice with deletion of both STAT5A and STAT5B in skeletal muscle (STAT5M−/−), when STAT5A is considered to have no role in growth [4, 6]. Furthermore, circulating IGF1 is likely not required for normal growth, and sexually dimorphic growth of mice persists in mice with overexpression of IGF1 and/or absence of myostatin [14, 15]. Importantly, previous reports on the role of STAT5B in murine skeletal muscle growth have not accounted for the reduced skeletal size and increased adiposity of GH deficiency, or extended beyond 12 weeks of age into adulthood [7–9]. Therefore, either sexually dimorphic growth of skeletal muscle persists in STAT5B−/− mice when changes in body composition are accounted for, or STAT5B regulates sexually dimorphic growth by mechanisms other than altering IGF1 and myostatin activity.
Sexually dimorphic growth of skeletal muscle has been attributed to opposing actions of the gonadal steroids, with androgens promoting and oestrogens inhibiting growth [16, 17]. Accordingly, deletion of either the androgen receptor (AR) or the oestrogen receptor alpha (ERα) reduces the sexual dimorphism of skeletal muscle [18, 19]. GH regulates the transcription of the Ar and Erα genes in skeletal muscle and other tissues [20, 21], but it is not known whether the expression of these receptors is reduced and, thereby, whether the actions of the gonadal steroids are decreased in STAT5B−/− mice. Sexually dimorphic growth has also been shown to be due to differences in the inhibition of GH signalling between sexes by suppressor of cytokine signalling 2 (SOCS2) and cytokine-inducible SH2-containing protein (CIS) [22, 23]. However, it is not known whether the expression of SOCS2 and CIS in skeletal muscle is sexually dimorphic or whether the expression is regulated by STAT5B. Consequently, the aims of our study were twofold: (1) to determine whether sexually dimorphic growth of skeletal muscle persists in STAT5B−/− mice when adjusting for changes in skeletal size and (2) to determine whether STAT5B regulates the expression of IGF1, AR, ERα, SOCS2, and CIS in skeletal muscle.
Male and female STAT5B−/− mice (C57BL/6 strain) and wild-type littermates were sacrificed at three time points: the onset of puberty (6 weeks of age), the end of puberty (12 weeks of age), and in early adulthood (24 weeks of age) by CO2 asphyxiation and cervical dislocation (n = 8 for each sex and genotype at each time point). Mice were weighed, and blood was collected by cardiac puncture. The hindlimb biceps femoris (BF), quadriceps, gastrocnemius, tibialis anterior (TA), extensor digitorium longus (EDL), and soleus muscles were excised, weighed, snap-frozen in liquid nitrogen and stored at − 80 °C. The soleus is a slow-twitch muscle, the TA and EDL are fast-twitch muscles, and the quadriceps, BF, and gastrocnemius muscles have a mixed composition of myofibres . Nasoanal (size of axial skeleton), tibia, and femur (appendicular skeleton) lengths were measured with digital callipers, and the masses of the gonadal and inguinal fat pads were recorded. The mean mass of each muscle group was normalised to the bone length upon which the muscle acted, to allow a comparison for the specific effects on the growth of skeletal muscle [25, 26]. The mass of both fat pads was normalised to total body mass, to allow a calculation of visceral (peri-gonadal) and subcutaneous (inguinal) fat. Plasma was harvested and stored at − 20 °C. All mice were maintained under a photoperiod of 14 h light to 10 h dark and had standard mouse chow (Specialty Feeds, Glen Forrest, Australia) and water ad libitum. There were no differences in age or litter size between groups at each time point (Additional file 1: Table S1).
RNA extraction and real-time PCR
Total RNA was isolated from frozen whole quadriceps muscles using the TRIzol® protocol as previously described . Concentrations and purity of RNA were determined by UV absorbance at 260/280 nm using a Nanodrop® 1000 spectrophotometer. Integrity of RNA was determined by running 1 μg of isolated RNA on an agarose gel with visualisation under UV light (GelDoc). Total RNA (2 μg) from each sample was reverse transcribed (RT) using oligo (dt) primers and SuperScript® III reverse transcriptase (Life Technologies, Carlsbad, California, USA) as per the manufacturer’s instructions. RT reactions were diluted 10-fold, and real-time PCR was performed using a Roche LightCycler® 2.0 as previously described . The sequences of primers used and size of the amplicons are listed in Additional file 2: Table S2. Concentrations of target cDNA were normalised to concentrations of total ssDNA for each RT sample using a Quant-iT™ Oligreen® ssDNA kit (Life Technologies) as per the manufacturer’s instructions .
Protein extraction and Western blot analysis
Protein was extracted from the quadriceps muscles, and Western blotting was performed as previously described  using antibodies listed in Additional file 3: Table S3. The relative abundance of the target protein for each sample was normalised to the abundance of total protein, as determined by densitometric analysis of multiple bands in high-resolution scanned images of the Ponceau stain .
MHC protein electrophoresis
Crude lysate samples from the quadriceps muscles were diluted in an 8-M urea/2-M thiourea buffer for MHC protein electrophoresis as previously described .
Plasma and skeletal muscle IGF1 assay
Concentrations of IGF1 protein in plasma and homogenates of quadriceps muscle were determined using a mouse/rat IGF1 Quantikine ELISA (R&D Systems, Minneapolis, USA) as per the manufacturer’s instructions . Concentrations of IGF1 in muscle were normalised to the total protein concentration in each homogenate.
Data were analysed by general ANOVA using GenStat v16 software (VSN International Ltd) with genotype, sex, and age as treatment terms. Residual plots were used to determine whether log transformation was required to stabilise the variance. Post hoc analyses were performed using Fisher’s unprotected test of least significant difference (LSD), which was restricted to intentional comparisons between groups. Two-tailed Student’s t tests were used for direct comparisons when there were only 2 variables. Significance was determined as a P value < 0.05, and data is presented as mean ± SEM.
STAT5B regulates the growth of both male and female mice
Lengths of the hindlimb bones (mm) and absolute mass of the hindlimb muscles (mg) of wild-type (WT) and STAT5B−/− mice
16.8 ± 0.2a
13.1 ± 0.3a
118 ± 4a
107 ± 2a
39 ± 1a
8.3 ± 0.2a
6.6 ± 0.3a
163 ± 4a
15.8 ± 0.2b
12.0 ± 0.2b
75 ± 3b
73 ± 2bc
27 ± 1b
6.2 ± 0.5b
5.6 ± 0.7abc
106 ± 2b
16.4 ± 0.2a
12.7 ± 0.3a
84 ± 4c
78 ± 3b
31 ± 1c
6.3 ± 0.3b
5.0 ± 0.2b
119 ± 6c
15.9 ± 0.1b
12.2 ± 0.1b
71 ± 3b
68 ± 2c
26 ± 1b
6.0 ± 0.4b
4.4 ± 0.1c
97 ± 2d
18.2 ± 0.2a
14.9 ± 0.1a
162 ± 8a
139 ± 2a
49 ± 1a
10.8 ± 0.3a
8.0 ± 0.5a
234 ± 5a
16.6 ± 0.2b
13.5 ± 0.2b
110 ± 4b
95 ± 3bc
35 ± 1b
7.4 ± 0.3b
6.0 ± 0.3b
143 ± 4b
17.7 ± 0.2c
14.5 ± 0.1c
121 ± 2c
101 ± 4b
39 ± 2c
10.1 ± 0.6a
6.9 ± 0.5ab
163 ± 4c
16.7 ± 0.2b
13.6 ± 0.1b
107 ± 4d
89 ± 2c
32 ± 1d
7.7 ± 0.2b
6.4 ± 0.5b
135 ± 2b
18.1 ± 0.1a
15.0 ± 0.1a
179 ± 4a
148 ± 3a
57 ± 2a
12.3 ± 0.8a
9.7 ± 0.5a
245 ± 7a
17.2 ± 0.2b
14.1 ± 0.1b
131 ± 7b
115 ± 4b
42 ± 1b
8.9 ± 0.3b
8.0 ± 0.3b
173 ± 6b
18.4 ± 0.2a
15.3 ± 0.2a
138 ± 9b
117 ± 5b
45 ± 2b
9.6 ± 0.4b
7.8 ± 0.3bc
187 ± 6b
17.4 ± 0.1b
14.4 ± 0.2b
111 ± 9c
111 ± 3b
36 ± 2c
7.5 ± 0.3c
7.1 ± 0.2c
168 ± 6c
Sexual dimorphism of skeletal muscle is reduced but persists in STAT5B−/− mice
STAT5B regulates concentrations of IGF1 in both sexes before puberty
Loss of STAT5B reduces the sexually dimorphic expression of SOCS2, CIS, AR, ERα, and myostatin in skeletal muscle
We have shown that when accounting for changes in body composition, STAT5B likely regulates the growth of the skeleton and skeletal muscles in both male and female adult mice. As per previous reports, we found that the body mass of female STAT5B−/− mice is not reduced, but demonstrate that this is due to increased visceral and subcutaneous adiposity despite the decreased skeletal size [7, 8]. Similarly, our data supports previous findings that the absolute mass of the gastrocnemius muscles is not decreased in female STAT5B−/− mice, but we demonstrate that the reduced growth of skeletal muscles in female STAT5B−/− mice is muscle-group specific . The reduction in circulating concentrations of IGF1 and growth of skeletal muscle and the axial and appendicular skeletons of both sexes of STAT5B−/− mice at the onset of puberty demonstrates that STAT5B−/− mice have a similar phenotype to GHR−/−, STAT5A−/−/STAT5B−/−, and STAT5M−/− mice [4, 6, 7]. These findings also address another important paradox, by confirming that the role of STAT5B is more similar between mice and humans than previously thought .
Our data are consistent with previous studies, wherein STAT5B was reported to regulate the sexually dimorphic expression of Igf1 and Ar mRNA and post-translational processing of myostatin protein in skeletal muscle [9, 15, 20, 37]. Our data are also consistent with a role for STAT5B in regulating the sexually dimorphic expression of Erα mRNA in skeletal muscle, which is important because transgenic models have shown that IGF1, myostatin, ERα, and AR all have individual roles in the sexually dimorphic growth of skeletal muscle [3, 15, 18, 19, 38]. In support, others have reported that STAT5A and STAT5B have differential roles in regulating Erα and may bind to the 0/B promoter of the gene in rats (C promoter in humans) [39, 40]. Furthermore, the reduced expression of AR and ERα and greater abundance of myostatin protein also likely contribute to the reduced skeletal muscle mass and increased adiposity of STAT5B−/− mice [18, 19, 38, 41]. The loss of androgen signalling may explain why only the growth of the TA and EDL muscles was reduced in female STAT5B−/− mice, because these muscles are fast-twitch muscles that are more androgen responsive than other muscle groups [24, 42]. Reduced activity of androgens may also be why, in contrast to GH-deficient rats, that STAT5B−/− mice have an oxidative rather than a glycolytic shift in the composition of myofibres . Indeed, further studies are required to delineate what effects from loss of STAT5B are due to loss of activity of the GH/IGF1 axis and/or androgens, and whether these effects are muscle group or species specific, particularly given the individual function and rate of growth of each muscle group [2, 44] and the differential expression of AR and ERα in skeletal muscle [45, 46].
Nevertheless, despite a likely switch in the role of STAT5B in regulating IGF1 and myostatin in female skeletal muscle following puberty, STAT5B appears to regulate the expression of AR, ERα, SOCS2, and CIS throughout the lifespan in both sexes (Fig. 7). The loss of STAT5B does not appear to be compensated for by the increased signalling of STAT5A because the expression of Stat5a mRNA and protein was reduced. Moreover, the finding that the expression of Stat5a mRNA is not reduced in the liver of the same model of STAT5B−/− mouse suggests that like STAT5B, STAT5A has tissue-specific roles . Indeed, we postulate that STAT5A is the principal regulator of the GH/IGF1 axis in adult female skeletal muscle, given that muscle growth is more retarded in female STAT5M−/− and STAT5A−/−/STAT5B−/− mice than in female STAT5B−/− mice [6, 7]. Further work is required to characterise the role of STAT5A in skeletal muscle, including identifying whether STAT5A or STAT5B is the most abundant isoform in skeletal muscle, as unlike in the liver, this is currently unknown .
Future studies are also required to determine whether the abundance of STAT5B protein reduces with advancing age in tissues other than skeletal muscle in male mice and whether similar changes occur in humans. These age-related changes in STAT5B protein in males and a switch in STAT5B signalling in females would be advantageous in maximising growth while young and reducing the risk of malignancy in adulthood [48, 49]. However, the mechanism for these changes is unclear given that we found that the expression of Stat5b mRNA in skeletal muscle does not change with advancing age in either sex.
We show that STAT5B appears to mediate the anabolic actions of GH in male mice of all ages, but only in female mice until puberty. STAT5B also appears to mediate the actions of androgens and oestrogens in murine skeletal muscle in both sexes, but sexually dimorphic growth persists in STAT5B−/− mice. Demonstrating that the expression of SOCS2 and CIS in skeletal muscle is sexually dimorphic provides new insights into how sexually dimorphic growth and expression of IGF1 and myostatin develop at the onset of puberty.
We thank Professor Dave Grattan for providing us with STAT5B−/− mice, Jeremy Bracegirdle for the assistance with genotyping, Harold Henderson for the statistical advice, and Trevor Watson, Ric Broadhurst, Genevieve Sheriff, and Bobby Smith for the care of the mice.
This study was supported by the Waikato Medical Research Foundation and the Royal Australasian College of Physicians.
RGP, MSE, JVC, and CDM contributed towards the study design. RGP and ASH performed the experimental work. RGP and CDM analysed the data. RP wrote the manuscript. All authors read and approved the final manuscript.
Ethics approval and consent to participate
This study was approved by the Ruakura Animal Ethics Committee.
Consent for publication
The authors declare that they have no competing interests.
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Komi PV, Karlsson J. Skeletal muscle fibre types, enzyme activities and physical performance in young males and females. Acta Physiol Scand. 1978;103:210–8. https://doi.org/10.1111/j.1748-1716.1978.tb06208.x.View ArticlePubMedGoogle Scholar
- White RB, Bierinx AS, Gnocchi VF, Zammit PS. Dynamics of muscle fibre growth during postnatal mouse development. BMC Dev Biol. 2010;10:21. https://doi.org/10.1186/1471-213X-10-21.View ArticlePubMedPubMed CentralGoogle Scholar
- Lupu F, Terwilliger JD, Lee K, Segre GV, Efstratiadis A. Roles of growth hormone and insulin-like growth factor 1 in mouse postnatal growth. Dev Biol. 2001;229:141–62. https://doi.org/10.1006/dbio.2000.9975.View ArticlePubMedGoogle Scholar
- List EO, Sackmann-Sala L, Berryman DE, Funk K, Kelder B, Gosney ES, et al. Endocrine parameters and phenotypes of the growth hormone receptor gene disrupted (GHR−/−) mouse. Endocr Rev. 2011;32:356–86. https://doi.org/10.1210/er.2010-0009.View ArticlePubMedGoogle Scholar
- Brooks AJ, Waters MJ. The growth hormone receptor: mechanism of activation and clinical implications. Nat Rev Endocrinol. 2010;6:515–25. https://doi.org/10.1038/nrendo.2010.123.View ArticlePubMedGoogle Scholar
- Klover P, Hennighausen L. Postnatal body growth is dependent on the transcription factors signal transducers and activators of transcription 5a/b in muscle: a role for autocrine/paracrine insulin-like growth factor I. Endocrinology. 2007;148:1489–97. https://doi.org/10.1210/en.2006-1431.View ArticlePubMedGoogle Scholar
- Teglund S, McKay C, Schuetz E, van Deursen JM, Stravopodis D, Wang D, et al. Stat5a and Stat5b proteins have essential and nonessential, or redundant, roles in cytokine responses. Cell. 1998;93:841–50 http://www.ncbi.nlm.nih.gov/pubmed/9630227.View ArticleGoogle Scholar
- Udy GB, Towers RP, Snell RG, Wilkins RJ, Park SH, Ram PA, et al. Requirement of STAT5b for sexual dimorphism of body growth rates and liver gene expression. Proc Natl Acad Sci U S A. 1997;94:7239–44 http://www.ncbi.nlm.nih.gov/pubmed/9207075.View ArticleGoogle Scholar
- Oldham JM, Osepchook CC, Jeanplong F, Falconer SJ, Matthews KG, Conaglen JV, et al. The decrease in mature myostatin protein in male skeletal muscle is developmentally regulated by growth hormone. J Physiol. 2009;587:669–77. https://doi.org/10.1113/jphysiol.2008.161521.View ArticlePubMedGoogle Scholar
- Morissette MR, Cook SA, Buranasombati C, Rosenberg MA, Rosenzweig A. Myostatin inhibits IGF-I-induced myotube hypertrophy through Akt. Am J Physiol Cell Physiol. 2009;297:C1124–32. https://doi.org/10.1152/ajpcell.00043.2009.View ArticlePubMedGoogle Scholar
- Amirouche A, Durieux AC, Banzet S, Koulmann N, Bonnefoy R, Mouret C, et al. Down-regulation of Akt/mammalian target of rapamycin signaling pathway in response to myostatin overexpression in skeletal muscle. Endocrinology. 2009;150:286–94. https://doi.org/10.1210/en.2008-0959.View ArticlePubMedGoogle Scholar
- Hennebry A, Oldham J, Shavlakadze T, Grounds MD, Sheard P, Fiorotto ML, et al. IGF1 stimulates greater muscle hypertrophy in the absence of myostatin in male mice. J Endocrinol. 2017;234:187–200. https://doi.org/10.1530/JOE-17-0032.View ArticlePubMedGoogle Scholar
- Hwa V. STAT5B deficiency: impacts on human growth and immunity. Growth Horm IGF Res. 2015. https://doi.org/10.1016/j.ghir.2015.12.006.View ArticleGoogle Scholar
- Yakar S, Liu JL, Stannard B, Butler A, Accili D, Sauer B, et al. Normal growth and development in the absence of hepatic insulin-like growth factor I. Proc Natl Acad Sci U S A. 1999;96:7324–9 http://www.ncbi.nlm.nih.gov/pubmed/10377413.View ArticleGoogle Scholar
- Paul RGWK, Falconer SJ, Oldham JM, Jeanplong F, Matthews KG, Smith HK, McMahon CD. Transgenic expression of IGF1 and absence of myostatin do not overcome sexual dimorphism of body and muscle size in mice. In: Submission; 2018.Google Scholar
- Axell AM, MacLean HE, Plant DR, Harcourt LJ, Davis JA, Jimenez M, et al. Continuous testosterone administration prevents skeletal muscle atrophy and enhances resistance to fatigue in orchidectomized male mice. Am J Physiol Endocrinol Metab. 2006;291:E506–16. https://doi.org/10.1152/ajpendo.00058.2006.View ArticlePubMedGoogle Scholar
- McCormick KM, Burns KL, Piccone CM, Gosselin LE, Brazeau GA. Effects of ovariectomy and estrogen on skeletal muscle function in growing rats. J Muscle Res Cell Motil. 2004;25:21–7 http://www.ncbi.nlm.nih.gov/pubmed/15160484.View ArticleGoogle Scholar
- MacLean HE, Chiu WS, Notini AJ, Axell AM, Davey RA, McManus JF, et al. Impaired skeletal muscle development and function in male, but not female, genomic androgen receptor knockout mice. FASEB J. 2008;22:2676–89. https://doi.org/10.1096/fj.08-105726.View ArticlePubMedGoogle Scholar
- Brown M, Ning J, Ferreira JA, Bogener JL, Lubahn DB. Estrogen receptor-alpha and -beta and aromatase knockout effects on lower limb muscle mass and contractile function in female mice. Am J Physiol Endocrinol Metab. 2009;296:E854–61. https://doi.org/10.1152/ajpendo.90696.2008.View ArticlePubMedPubMed CentralGoogle Scholar
- Klover P, Chen W, Zhu BM, Hennighausen L. Skeletal muscle growth and fiber composition in mice are regulated through the transcription factors STAT5a/b: linking growth hormone to the androgen receptor. FASEB J. 2009;23:3140–8. https://doi.org/10.1096/fj.08-128215.View ArticlePubMedPubMed CentralGoogle Scholar
- Feldman M, Ruan W, Tappin I, Wieczorek R, Kleinberg DL. The effect of GH on estrogen receptor expression in the rat mammary gland. J Endocrinol. 1999;163:515–22 http://www.ncbi.nlm.nih.gov/pubmed/10588825.View ArticleGoogle Scholar
- Matsumoto A, Seki Y, Kubo M, Ohtsuka S, Suzuki A, Hayashi I, et al. Suppression of STAT5 functions in liver, mammary glands, and T cells in cytokine-inducible SH2-containing protein 1 transgenic mice. Mol Cell Biol. 1999;19:6396–407 http://www.ncbi.nlm.nih.gov/pubmed/10454585.View ArticleGoogle Scholar
- Greenhalgh CJ, Bertolino P, Asa SL, Metcalf D, Corbin JE, Adams TE, et al. Growth enhancement in suppressor of cytokine signaling 2 (SOCS-2)-deficient mice is dependent on signal transducer and activator of transcription 5b (STAT5b). Mol Endocrinol. 2002;16:1394–406. https://doi.org/10.1210/mend.16.6.0845.View ArticlePubMedGoogle Scholar
- Augusto V, Padovani CR, Campos GR. Skeletal muscle fiber types in C57BL6J mice. Braz J Morphol Sci. 2004;21:89–94.Google Scholar
- Soffe Z, Radley-Crabb HG, McMahon C, Grounds MD, Shavlakadze T. Effects of loaded voluntary wheel exercise on performance and muscle hypertrophy in young and old male C57Bl/6J mice. Scand J Med Sci Sports. 2016;26:172–88. https://doi.org/10.1111/sms.12416.View ArticlePubMedGoogle Scholar
- White Z, White RB, McMahon C, Grounds MD, Shavlakadze T. High mTORC1 signaling is maintained, while protein degradation pathways are perturbed in old murine skeletal muscles in the fasted state. Int J Biochem Cell Biol. 2016;78:10–21. https://doi.org/10.1016/j.biocel.2016.06.012.View ArticlePubMedGoogle Scholar
- Lundby C, Nordsborg N, Kusuhara K, Kristensen KM, Neufer PD, Pilegaard H. Gene expression in human skeletal muscle: alternative normalization method and effect of repeated biopsies. Eur J Appl Physiol. 2005;95:351–60. https://doi.org/10.1007/s00421-005-0022-7.View ArticlePubMedGoogle Scholar
- Eaton SL, Roche SL, Llavero Hurtado M, Oldknow KJ, Farquharson C, Gillingwater TH, et al. Total protein analysis as a reliable loading control for quantitative fluorescent Western blotting. PLoS One. 2013;8:e72457. https://doi.org/10.1371/journal.pone.0072457.View ArticlePubMedPubMed CentralGoogle Scholar
- Smith HK, Matthews KG, Oldham JM, Jeanplong F, Falconer SJ, Bass JJ, et al. Translational signalling, atrogenic and myogenic gene expression during unloading and reloading of skeletal muscle in myostatin-deficient mice. PLoS One. 2014;9:e94356. https://doi.org/10.1371/journal.pone.0094356.View ArticlePubMedPubMed CentralGoogle Scholar
- Nuytens K, Tuand K, Fu Q, Stijnen P, Pruniau V, Meulemans S, et al. The dwarf phenotype in GH240B mice, haploinsufficient for the autism candidate gene Neurobeachin, is caused by ectopic expression of recombinant human growth hormone. PLoS One. 2014;9:e109598. https://doi.org/10.1371/journal.pone.0109598.View ArticlePubMedPubMed CentralGoogle Scholar
- Ram PA, Park SH, Choi HK, Waxman DJ. Growth hormone activation of Stat 1, Stat 3, and Stat 5 in rat liver. Differential kinetics of hormone desensitization and growth hormone stimulation of both tyrosine phosphorylation and serine/threonine phosphorylation. J Biol Chem. 1996;271:5929–40 http://www.ncbi.nlm.nih.gov/pubmed/8621467.View ArticleGoogle Scholar
- Gebert CA, Park SH, Waxman DJ. Down-regulation of liver JAK2-STAT5b signaling by the female plasma pattern of continuous growth hormone stimulation. Mol Endocrinol. 1999;13:213–27. https://doi.org/10.1210/mend.13.2.0238.View ArticlePubMedGoogle Scholar
- Wang D, Moriggl R, Stravopodis D, Carpino N, Marine JC, Teglund S, et al. A small amphipathic alpha-helical region is required for transcriptional activities and proteasome-dependent turnover of the tyrosine-phosphorylated Stat5. EMBO J. 2000;19:392–9. https://doi.org/10.1093/emboj/19.3.392.View ArticlePubMedPubMed CentralGoogle Scholar
- Uyttendaele I, Lemmens I, Verhee A, De Smet AS, Vandekerckhove J, Lavens D, et al. Mammalian protein-protein interaction trap (MAPPIT) analysis of STAT5, CIS, and SOCS2 interactions with the growth hormone receptor. Mol Endocrinol. 2007;21:2821–31. https://doi.org/10.1210/me.2006-0541.View ArticlePubMedGoogle Scholar
- Vesterlund M, Zadjali F, Persson T, Nielsen ML, Kessler BM, Norstedt G, et al. The SOCS2 ubiquitin ligase complex regulates growth hormone receptor levels. PLoS One. 2011;6:e25358. https://doi.org/10.1371/journal.pone.0025358.View ArticlePubMedPubMed CentralGoogle Scholar
- Thangavel C, Shapiro BH. A molecular basis for the sexually dimorphic response to growth hormone. Endocrinology. 2007;148:2894–903. https://doi.org/10.1210/en.2006-1333.View ArticlePubMedGoogle Scholar
- Davey HW, McLachlan MJ, Wilkins RJ, Hilton DJ, Adams TE. STAT5b mediates the GH-induced expression of SOCS-2 and SOCS-3 mRNA in the liver. Mol Cell Endocrinol. 1999;158:111–6 http://www.ncbi.nlm.nih.gov/pubmed/10630411.View ArticleGoogle Scholar
- Reisz-Porszasz S, Bhasin S, Artaza JN, Shen R, Sinha-Hikim I, Hogue A, et al. Lower skeletal muscle mass in male transgenic mice with muscle-specific overexpression of myostatin. Am J Physiol Endocrinol Metab. 2003;285:E876–88. https://doi.org/10.1152/ajpendo.00107.2003.View ArticlePubMedGoogle Scholar
- Wilson ME, Westberry JM, Prewitt AK. Dynamic regulation of estrogen receptor-alpha gene expression in the brain: a role for promoter methylation? Front Neuroendocrinol. 2008;29:375–85. https://doi.org/10.1016/j.yfrne.2008.03.002.View ArticlePubMedPubMed CentralGoogle Scholar
- Frasor J, Park K, Byers M, Telleria C, Kitamura T, Yu-Lee LY, et al. Differential roles for signal transducers and activators of transcription 5a and 5b in PRL stimulation of ERalpha and ERbeta transcription. Mol Endocrinol. 2001;15:2172–81. https://doi.org/10.1210/mend.15.12.0745.View ArticlePubMedGoogle Scholar
- Heine PA, Taylor JA, Iwamoto GA, Lubahn DB, Cooke PS. Increased adipose tissue in male and female estrogen receptor-alpha knockout mice. Proc Natl Acad Sci U S A. 2000;97:12729–34. https://doi.org/10.1073/pnas.97.23.12729.View ArticlePubMedPubMed CentralGoogle Scholar
- Chambon C, Duteil D, Vignaud A, Ferry A, Messaddeq N, Malivindi R, et al. Myocytic androgen receptor controls the strength but not the mass of limb muscles. Proc Natl Acad Sci U S A. 2010;107:14327–32. https://doi.org/10.1073/pnas.1009536107.View ArticlePubMedPubMed CentralGoogle Scholar
- Daugaard JR, Laustsen JL, Hansen BS, Richter EA. Growth hormone induces muscle fibre type transformation in growth hormone-deficient rats. Acta Physiol Scand. 1998;164:119–26. https://doi.org/10.1046/j.1365-201X.1998.00409.x.View ArticlePubMedGoogle Scholar
- Sheard PW, Anderson RD. Age-related loss of muscle fibres is highly variable amongst mouse skeletal muscles. Biogerontology. 2012;13:157–67. https://doi.org/10.1007/s10522-011-9365-0.View ArticlePubMedGoogle Scholar
- De Naeyer H, Lamon S, Russell AP, Everaert I, De Spaey A, Vanheel B, et al. Androgenic and estrogenic regulation of Atrogin-1, MuRF1 and myostatin expression in different muscle types of male mice. Eur J Appl Physiol. 2014;114:751–61. https://doi.org/10.1007/s00421-013-2800-y.View ArticlePubMedGoogle Scholar
- Baltgalvis KA, Greising SM, Warren GL, Lowe DA. Estrogen regulates estrogen receptors and antioxidant gene expression in mouse skeletal muscle. PLoS One. 2010;5:e10164. https://doi.org/10.1371/journal.pone.0010164.View ArticlePubMedPubMed CentralGoogle Scholar
- Park SH, Liu X, Hennighausen L, Davey HW, Waxman DJ. Distinctive roles of STAT5a and STAT5b in sexual dimorphism of hepatic P450 gene expression. Impact of STAT5a gene disruption. J Biol Chem. 1999;274:7421–30. http://www.ncbi.nlm.nih.gov/pubmed/10066807.View ArticleGoogle Scholar
- Bartke A, Sun LY, Longo V. Somatotropic signaling: trade-offs between growth, reproductive development, and longevity. Physiol Rev. 2013;93:571–98. https://doi.org/10.1152/physrev.00006.2012.View ArticlePubMedPubMed CentralGoogle Scholar
- Mitra A, Ross JA, Rodriguez G, Nagy ZS, Wilson HL, Kirken RA. Signal transducer and activator of transcription 5b (Stat5b) serine 193 is a novel cytokine-induced phospho-regulatory site that is constitutively activated in primary hematopoietic malignancies. J Biol Chem. 2012;287:16596–608. https://doi.org/10.1074/jbc.M111.319756.View ArticlePubMedPubMed CentralGoogle Scholar