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Gtf2ird1-Dependent Mohawk Expression Regulates Mechanosensing Properties of the Tendon.

Kayama T, Mori M, Ito Y, Matsushima T, Nakamichi R, Suzuki H, Ichinose S, Saito M, Marumo K, Asahara H - Mol. Cell. Biol. (2016)

Bottom Line: In mammals, the tendon connective tissue experiences and resists physical forces, with tendon-specific mesenchymal cells called tenocytes orchestrating extracellular matrix (ECM) turnover.Furthermore, functional screening of the Mkx promoter region identified several upstream transcription factors that regulate Mkx In particular, general transcription factor II-I repeat domain-containing protein 1 (Gtf2ird1) that is expressed in the cytoplasm of unstressed tenocytes translocated into the nucleus upon mechanical stretching to activate the Mkx promoter through chromatin regulation.Here, we demonstrate that Gtf2ird1 is essential for Mkx transcription, while also linking mechanical forces to Mkx-mediated tendon homeostasis and regeneration.

View Article: PubMed Central - PubMed

Affiliation: Department of Systems BioMedicine, Tokyo Medical and Dental University, Tokyo, Japan Department of Orthopaedic Surgery, The Jikei University School of Medicine, Tokyo, Japan.

No MeSH data available.


Related in: MedlinePlus

Mechanical stretching induces Mkx in primary rat tenocytes in vitro. (A) Protocol for obtaining primary rat tenocytes. Tenocytes before passage 5 were used for experiments. Isolated tenocytes were seeded onto collagen-coated chambers and incubated overnight before stretching at 2% at 0.25 Hz for 6 h. (B) Mkx and the downstream tendon-associated genes Tnmd, Col1a1, and Col1a2, but not Scx, were elevated as a result of tenocyte stretching under specific conditions. Error bars represent standard errors of the means (*, P < 0.05, two-tailed Student's t test).
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Figure 3: Mechanical stretching induces Mkx in primary rat tenocytes in vitro. (A) Protocol for obtaining primary rat tenocytes. Tenocytes before passage 5 were used for experiments. Isolated tenocytes were seeded onto collagen-coated chambers and incubated overnight before stretching at 2% at 0.25 Hz for 6 h. (B) Mkx and the downstream tendon-associated genes Tnmd, Col1a1, and Col1a2, but not Scx, were elevated as a result of tenocyte stretching under specific conditions. Error bars represent standard errors of the means (*, P < 0.05, two-tailed Student's t test).

Mentions: Physical forces induced Mkx and tendon-related genes in vivo. In order to assess the role of Mkx at the cellular level, Achilles tendon-derived primary rat tenocytes were subjected to cellular stretching (Fig. 3A). In primary rat tenocytes, Mkx induction was most prominent when the tenocytes were stretched using a 2% sinusoidal wave pattern at 0.25 Hz cyclic strain for 6 h. The expression levels of ECM genes downstream of Mkx, such as Tnmd, Col1a1, and Col1a2, were also increased, indicating that ECM genes are also responsive in this particular experimental protocol (Fig. 3B). However, Scx, another tendon marker that has been reported to have sensitivity to stretching, did not increase. These results show that tenocytes are load-sensitive mechanosensors, inducing Mkx-mediated tendon marker expression under specific conditions.


Gtf2ird1-Dependent Mohawk Expression Regulates Mechanosensing Properties of the Tendon.

Kayama T, Mori M, Ito Y, Matsushima T, Nakamichi R, Suzuki H, Ichinose S, Saito M, Marumo K, Asahara H - Mol. Cell. Biol. (2016)

Mechanical stretching induces Mkx in primary rat tenocytes in vitro. (A) Protocol for obtaining primary rat tenocytes. Tenocytes before passage 5 were used for experiments. Isolated tenocytes were seeded onto collagen-coated chambers and incubated overnight before stretching at 2% at 0.25 Hz for 6 h. (B) Mkx and the downstream tendon-associated genes Tnmd, Col1a1, and Col1a2, but not Scx, were elevated as a result of tenocyte stretching under specific conditions. Error bars represent standard errors of the means (*, P < 0.05, two-tailed Student's t test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4836271&req=5

Figure 3: Mechanical stretching induces Mkx in primary rat tenocytes in vitro. (A) Protocol for obtaining primary rat tenocytes. Tenocytes before passage 5 were used for experiments. Isolated tenocytes were seeded onto collagen-coated chambers and incubated overnight before stretching at 2% at 0.25 Hz for 6 h. (B) Mkx and the downstream tendon-associated genes Tnmd, Col1a1, and Col1a2, but not Scx, were elevated as a result of tenocyte stretching under specific conditions. Error bars represent standard errors of the means (*, P < 0.05, two-tailed Student's t test).
Mentions: Physical forces induced Mkx and tendon-related genes in vivo. In order to assess the role of Mkx at the cellular level, Achilles tendon-derived primary rat tenocytes were subjected to cellular stretching (Fig. 3A). In primary rat tenocytes, Mkx induction was most prominent when the tenocytes were stretched using a 2% sinusoidal wave pattern at 0.25 Hz cyclic strain for 6 h. The expression levels of ECM genes downstream of Mkx, such as Tnmd, Col1a1, and Col1a2, were also increased, indicating that ECM genes are also responsive in this particular experimental protocol (Fig. 3B). However, Scx, another tendon marker that has been reported to have sensitivity to stretching, did not increase. These results show that tenocytes are load-sensitive mechanosensors, inducing Mkx-mediated tendon marker expression under specific conditions.

Bottom Line: In mammals, the tendon connective tissue experiences and resists physical forces, with tendon-specific mesenchymal cells called tenocytes orchestrating extracellular matrix (ECM) turnover.Furthermore, functional screening of the Mkx promoter region identified several upstream transcription factors that regulate Mkx In particular, general transcription factor II-I repeat domain-containing protein 1 (Gtf2ird1) that is expressed in the cytoplasm of unstressed tenocytes translocated into the nucleus upon mechanical stretching to activate the Mkx promoter through chromatin regulation.Here, we demonstrate that Gtf2ird1 is essential for Mkx transcription, while also linking mechanical forces to Mkx-mediated tendon homeostasis and regeneration.

View Article: PubMed Central - PubMed

Affiliation: Department of Systems BioMedicine, Tokyo Medical and Dental University, Tokyo, Japan Department of Orthopaedic Surgery, The Jikei University School of Medicine, Tokyo, Japan.

No MeSH data available.


Related in: MedlinePlus