Abstract
Shivering frequency scales predictably with body mass and is 10 times higher in a mouse than a moose. The link between shivering frequency and body mass may lie in the tuning of muscle elastic properties. Titin functions as a muscle 'spring', so shivering frequency may be linked to titin's structure. The muscular dystrophy with myositis (mdm) mouse is characterized by a deletion in titin's N2A region. Mice that are homozygous for the mdm mutation have a lower body mass, stiffer gait and reduced lifespan compared with their wild-type and heterozygous siblings. We characterized thermoregulation in these mice by measuring metabolic rate and tremor frequency during shivering. Mutants were heterothermic at ambient temperatures of 20-37C while wild-type and heterozygous mice were homeothermic. Metabolic rate increased at smaller temperature differentials (i.e. The difference between body and ambient temperatures) in mutants than in nonmutants. The difference between observed tremor frequencies and shivering frequencies predicted by body mass was significantly larger for mutant mice than for wild-type or heterozygous mice, even after accounting for differences in body temperature. Together, the heterothermy in mutants, the increase in metabolic rate at low temperature differentials and the decreased tremor frequency demonstrate the thermoregulatory challenges faced by mice with the mdm mutation. Oscillatory frequency is proportional to the square root of stiffness, and we observed that mutants had lower active muscle stiffness in vitro. The lower tremor frequencies in mutants are consistent with reduced active muscle stiffness and suggest that titin affects the tuning of shivering frequency.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 694-702 |
| Number of pages | 9 |
| Journal | Journal of Experimental Biology |
| Volume | 218 |
| Issue number | 5 |
| DOIs | |
| State | Published - Mar 1 2015 |
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Keywords
- Mdm
- Mouse
- Muscle
- Stiffness
- Thermoregulation
ASJC Scopus subject areas
- Animal Science and Zoology
- Ecology, Evolution, Behavior and Systematics
- Molecular Biology
- Physiology
- Insect Science
- Aquatic Science
Cite this
Shiver me titin! Elucidating titin's role in shivering thermogenesis. / Taylor-Burt, Kari R.; Monroy, Jenna; Pace, Cinnamon; Lindstedt, Stan L; Nishikawa, Kiisa C.
In: Journal of Experimental Biology, Vol. 218, No. 5, 01.03.2015, p. 694-702.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Shiver me titin! Elucidating titin's role in shivering thermogenesis
AU - Taylor-Burt, Kari R.
AU - Monroy, Jenna
AU - Pace, Cinnamon
AU - Lindstedt, Stan L
AU - Nishikawa, Kiisa C
PY - 2015/3/1
Y1 - 2015/3/1
N2 - Shivering frequency scales predictably with body mass and is 10 times higher in a mouse than a moose. The link between shivering frequency and body mass may lie in the tuning of muscle elastic properties. Titin functions as a muscle 'spring', so shivering frequency may be linked to titin's structure. The muscular dystrophy with myositis (mdm) mouse is characterized by a deletion in titin's N2A region. Mice that are homozygous for the mdm mutation have a lower body mass, stiffer gait and reduced lifespan compared with their wild-type and heterozygous siblings. We characterized thermoregulation in these mice by measuring metabolic rate and tremor frequency during shivering. Mutants were heterothermic at ambient temperatures of 20-37C while wild-type and heterozygous mice were homeothermic. Metabolic rate increased at smaller temperature differentials (i.e. The difference between body and ambient temperatures) in mutants than in nonmutants. The difference between observed tremor frequencies and shivering frequencies predicted by body mass was significantly larger for mutant mice than for wild-type or heterozygous mice, even after accounting for differences in body temperature. Together, the heterothermy in mutants, the increase in metabolic rate at low temperature differentials and the decreased tremor frequency demonstrate the thermoregulatory challenges faced by mice with the mdm mutation. Oscillatory frequency is proportional to the square root of stiffness, and we observed that mutants had lower active muscle stiffness in vitro. The lower tremor frequencies in mutants are consistent with reduced active muscle stiffness and suggest that titin affects the tuning of shivering frequency.
AB - Shivering frequency scales predictably with body mass and is 10 times higher in a mouse than a moose. The link between shivering frequency and body mass may lie in the tuning of muscle elastic properties. Titin functions as a muscle 'spring', so shivering frequency may be linked to titin's structure. The muscular dystrophy with myositis (mdm) mouse is characterized by a deletion in titin's N2A region. Mice that are homozygous for the mdm mutation have a lower body mass, stiffer gait and reduced lifespan compared with their wild-type and heterozygous siblings. We characterized thermoregulation in these mice by measuring metabolic rate and tremor frequency during shivering. Mutants were heterothermic at ambient temperatures of 20-37C while wild-type and heterozygous mice were homeothermic. Metabolic rate increased at smaller temperature differentials (i.e. The difference between body and ambient temperatures) in mutants than in nonmutants. The difference between observed tremor frequencies and shivering frequencies predicted by body mass was significantly larger for mutant mice than for wild-type or heterozygous mice, even after accounting for differences in body temperature. Together, the heterothermy in mutants, the increase in metabolic rate at low temperature differentials and the decreased tremor frequency demonstrate the thermoregulatory challenges faced by mice with the mdm mutation. Oscillatory frequency is proportional to the square root of stiffness, and we observed that mutants had lower active muscle stiffness in vitro. The lower tremor frequencies in mutants are consistent with reduced active muscle stiffness and suggest that titin affects the tuning of shivering frequency.
KW - Mdm
KW - Mouse
KW - Muscle
KW - Stiffness
KW - Thermoregulation
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UR - http://www.scopus.com/inward/citedby.url?scp=84964292762&partnerID=8YFLogxK
U2 - 10.1242/jeb.111849
DO - 10.1242/jeb.111849
M3 - Article
VL - 218
SP - 694
EP - 702
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
SN - 0022-0949
IS - 5
ER -