B6.129S4-Pmch^tm1Emf/J

Stock number: 014137
Product name: MCH^-
Research areas: Endocrine Deficiency Research, Internal/Organ Research, Metabolism Research, Research Tools

Description

This MCH (melanin-concentrating hormone) knock-out strain exhibits a lean, hyperactive, hypermetabolic phenotype and may be useful in studies of energy homeostasis and balance, sleep disorders, obesity, and metabolism.

Detailed description

Mice that are homozygous for this knockout are viable, fertile, and exhibit a smaller stature and increased locomotor activity when compared to wildtype controls. No gene product (mRNA or protein) is detected by RT-PCR and in situ hybridization analysis of hypothalamus tissue, RT-PCR of pancreatic islets from homozygotes and immunocytochemical analysis of brain tissue from homozygotes. Homozygotes appear smaller, are leaner than wildtype controls and when placed on a chow diet, display increased basal metabolic rates and locomotor activity. When fed a high-fat diet, the oxygen consumption ( by 15.7%) and activity levels are further increased and homozygotes do not gain as much weight as controls. The lean phenotype persists in homozygous mice more than 12 months of age. Homozygotes, 12-19 months of age, are more sensitive to insulin, have reduced aging-associated weight and visceral adiposity gain, maintain increased locomotor activity, and are resistant to aging-associated glucose intolerance. Pancreas tissue from homozygotes have smaller islets and decreased beta cell mass. Homozygotes fed a high fat diet do not exhibit the increase in beta cell mass observed in wildtype controls. Homozygotes have shorter sleep periods (increased wakefulness), and under fasting conditions exhibit accelerated weight loss and reduced REM sleep. The Donating Investigator reports that homozygous females have reduced litter size and pup survival.

Development

A targeting vector containing a PGK-Neo cassette was used to disrupt exons 1 through 3, which is the entire coding region for the gene. The construct was electroporated into 129S4/SvJae derived J1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The donating investigator reports that the resulting chimeric animals were crossed to C57BL/6 mice, and then backcrossed to C57BL/6 for at least 20 generations (see SNP note below). Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.

A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 4 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.

Allele

Symbol: Pmch^tm1Emf
Name: targeted mutation 1, Eleftheria Maratos-Flier
MGI accession ID: MGI:2445313
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Pmch
Marker name: pro-melanin-concentrating hormone
Chromosome: 10
Strain of origin: 129S4/SvJae
Molecular note: Exons 1 through 3 were replaced with a neomycin selection cassette. RT-PCR and in situ hybridization indicated an absence of normal transcript. Protein was undetected in brain tissue obtained from homozygous mutant mice.