Expression and localization of aquaporin 7 in normal skeletal myofiber

Wakayama, Yoshihiro; Inoue, Masahiko; Kojima, Hiroko; Jimi, Takahiro; Shibuya, Seiji; Hara, Hajime; Oniki, Hiroaki

doi:10.1007/s00441-004-0857-y

Cited by 42 publications

(35 citation statements)

References 24 publications

(25 reference statements)

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“…Water permeation across the sarcolemma of skeletal muscle is mediated by aquaporins (AQP). AQP exist in several isoforms, among which AQP1, -3, and -7 are expressed in adult rat skeletal muscles (382,840,841) with no difference among fiber types. In contrast, expression of AQP4 is restricted to fast-twitch fibers of mammalian skeletal muscles, and such selective expression might account for the faster osmotic response of rat EDL compared with soleus (236).…”

Section: Trans-sarcolemmal Substrate Transportmentioning

confidence: 99%

Fiber Types in Mammalian Skeletal Muscles

Schiaffino

Reggiani

2011

Physiological Reviews

2,227

2,465

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Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.

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Section: Trans-sarcolemmal Substrate Transportmentioning

confidence: 99%

Fiber Types in Mammalian Skeletal Muscles

Schiaffino

Reggiani

2011

Physiological Reviews

2,227

2,465

View full text Add to dashboard Cite

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“…The previously described general procedures were used for peptide syntheses and antibody production [16,17]. Briefly, the peptide (MVQASGHRRSTRGSK-C) of the N-terminal end of the cytoplasmic domain in the human AQP7 molecule (Entrez NM001170) and the peptide (KAEQSEDKPEKYE-C) of the C-terminal end of the cytoplasmic domain in the human AQP9 molecule (Entrez NM020980) were respectively synthesized and the extra cysteine was added to the C-terminus of AQP7 and AQP9 molecules.…”

Section: Peptide Synthesis and Antibody Productionmentioning

confidence: 99%

AQP7 Up-Regulation in the Skeletal Muscles of Mice with Diet Induced Obesity

Wakayama¹

2015

J Cell Sci Ther

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Aquaporin (AQP) 7 and AQP9 are membrane proteins and are the members of aquaglyceroporin which transports glycerol in addition to water molecule. Glycerol is a direct source of glycerol-3 phosphate for the synthesis of triglycerides. We thought that the expression of AQP7 and AQP9 would be altered in the skeletal myofibers in mice with diet-induced obesity (DIO) as compared with that of control chaw-fed mice. RNA and protein levels of AQP7 and AQP9 were studied in the quadriceps femoris muscles of mice with DIO and normal control mice. Real time quantitative RT-PCR analysis showed that mouse AQP7 mRNA levels in skeletal muscles were significantly higher in mice with DIO than in normal control mice (P<0.01); whereas mouse AQP9 mRNA levels were not different between the two groups (P>0.05). Histochemically the myofibers of mice with DIO contained numerous lipid droplets in oil red O stain samples. Immunohistochemical study of DIO mouse muscles showed enhanced expression of AQP7 at the myofiber surface membranes; while AQP9 expression appeared to be similar to that of normal control mice. These findings imply that the up-regulated expression of AQP7 in DIO mouse muscles facilitates the secretion of glycerol from myocytes.

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“…In mammals, AQP7 has a relatively narrow tissue distribution, and focus has been on the role as a glycerol channel in association with adipose and liver tissue (Rodríguez et al, 2011). AQP7 is also expressed in the apical brushborder of the rat small intestine, where it may play a role in water movement in the apical domain of enterocytes (Laforenza et al, 2005); in the apical membrane of rat proximal straight tubules, where its role may be in water absorption or urea secretion, thus participating in the concentrating mechanism of the mammalian kidney (Ishibashi et al, 2000a); and finally, AQP7 was localized in the plasma membrane of skeletal muscle fibers (Wakayama et al, 2004), where its function is as yet unknown.…”

Section: Research Articlementioning

confidence: 99%

Aquaporin expression in the Japanese medaka (Oryzias latipes, Temminck & Schlegel) in FW and SW: challenging the paradigm for intestinal water transport?

Madsen

Bujak

Tipsmark

2014

Journal of Experimental Biology

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We investigated the salinity-dependent expression dynamics of seven aquaporin paralogs (aqp1a, aqp3a, aqp7, aqp8ab, aqp10a, aqp10b and aqp11a) in several tissues of euryhaline Japanese medaka (Oryzias latipes). All paralogs except aqp7 and aqp10a had a broad tissue distribution, and several were affected by salinity in both osmoregulatory and non-osmoregulatory tissues. In the intestine, aqp1a, aqp7, aqp8ab and aqp10a decreased upon seawater (SW) acclimation in both long-term acclimated fish and during 1-3 days of the transition period. In the gill, aqp3a was lower and aqp10a higher in SW than in freshwater (FW). In the kidney no aqps were affected by salinity. In the skin, aqp1a and aqp3a were lower in SW than in FW. In the liver, aqp8ab and aqp10a were lower in SW than in FW. Furthermore, six Na + ,K + -ATPase α-subunit isoform transcripts were analysed in the intestine but none showed a consistent response to salinity, suggesting that water transport is not regulated at this level. In contrast, mRNA of the Na + ,K + ,2Cl --cotransporter type-2 strongly increased in the intestine in SW compared with FW fish. Using custom-made antibodies, Aqp1a, Aqp8ab and Aqp10a were localized in the apical region of enterocytes of FW fish. Apical staining intensity strongly decreased, vanished or moved to subapical regions, when fish were acclimated to SW, supporting the lower mRNA expression in SW. Western blots confirmed the decrease in Aqp1a and Aqp10a in SW. The strong decrease in aquaporin expression in the intestine of SW fish is surprising, and challenges the paradigm for transepithelial intestinal water absorption in SW fishes.

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Expression and localization of aquaporin 7 in normal skeletal myofiber

Cited by 42 publications

References 24 publications

Fiber Types in Mammalian Skeletal Muscles

Fiber Types in Mammalian Skeletal Muscles

AQP7 Up-Regulation in the Skeletal Muscles of Mice with Diet Induced Obesity

Aquaporin expression in the Japanese medaka (Oryzias latipes, Temminck & Schlegel) in FW and SW: challenging the paradigm for intestinal water transport?

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