Hypoxia-inducible myoglobin expression in nonmuscle tissues.
Myoglobin (Myg) is an oxygen-binding hemoprotein that is widely thought to be expressed exclusively in oxidative skeletal and cardiac myocytes, where it plays a key role in coping with chronic hypoxia. We now show in a hypoxia-tolerant fish model, that Myg is also expressed in a range of other tissues, including liver, gill, and brain. Moreover, expression of Myg transcript was substantially enhanced during chronic hypoxia, the fold-change induction being far greater in liver than muscle. By using 2D gel electrophoresis, we have confirmed that liver expresses a protein corresponding to the Myg-1 transcript and that it is significantly up-regulated during hypoxia. We have also discovered a second, unique Myg isoform, distinct from neuroglobin, which is expressed exclusively in the neural tissue but whose transcript expression was unaffected by environmental hypoxia. Both observations of nonmuscle expression and a brain-specific isoform are unprecedented, indicating that Myg may play a much wider role than previously understood and that Myg might function in the protection of tissues from deep hypoxia and ischemia as well as in reoxygenation and reperfusion injury.
Fraser
Jane
J
School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom.
de Mello
Luciane Vieira
LV
Ward
Deborah
D
Rees
Huw H
HH
Williams
Daryl R
DR
Fang
Yongxiang
Y
Fang
Yongchang
Y
Brass
Andrew
A
Gracey
Andrew Y
AY
Cossins
Andrew R
AR
D000595:Amino Acid Sequence; D000693:Anaerobiosis / Q000235:genetics; D000818:Animals; D002347:Carps / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia; D029941:Fish Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D008099:Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D009211:Myoglobin / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D014018:Tissue Distribution
D029941:Fish Proteins; D009211:Myoglobin