Plast1b^CASA/Rk
QTL Variant Detail

Summary

• QTL variant: Plast1b^CASA/Rk
• Name: plasma plant sterol 1b; CASA/Rk
• MGI ID: MGI:3703629
• Synonyms: 14DKK
• QTL: Plast1b Location: unknown Genetic Position: Chr14, cM position of peak correlated region/allele: 27.65 cM
• QTL Note: genome coordinates based on the boundaries of the QTL region

Variant origin

• Strain of Specimen: CASA/Rk

Variant description

• Allele Type: QTL
• Mutation: Undefined
• Mutation details: This allele confers decreased plasma plant sterol concentration and decreased cholesterol absorption compared to C57BL/6J. This allele also confers decreased absolute biliary plant sterol concentration and bile-to-plasma plant sterol ratio in females. (J:116492)

Expression

In Structures Affected by this Mutation:

1 anatomical structure(s)

Notes

Mapping and Phenotype information for this QTL, its variants and associated markers

J:116492

A previously identified locus for plasma plant sterol levels, Plast1, was further examined using congenic line analysis. Plast1 mappped to 17 cM on mouse Chromosome 14 with a QTL interval spanning 5 cM - 40 cM. A congenic line named 14KK was constructed by introgression of CASA/Rk-derived chromosome 14 DNA from 4 cM - 60 cM onto a C57BL/6J genetic background. Congenic line 14KK was then used to create two non-overlapping subcongenic lines named 14PKK and 14DKK. Donor strain CASA/Rk displays decreased plasma plant sterol levels compared to background strain C57BL/6J. Animals were phenotyped at 11 weeks of age.

14KK (full congenic) males displayed significantly decreased plasma campesterol, sitosterol, stigmasterol, and brassicasterol levels compared to C57BL/6J controls. However, plasma plant sterol levels in 14KK females did not differ from controls. This finding reaffirms the presence of Plast1 on chromosome 14 and revealsa sex-dependent effect. Cholesterol absorption rate, but not food intake, was significantly lower in 14KK males compared to C57BL/6J males. Therefore, the effect of Plast1 in decreasing plasma plant sterol levels in males is likely explained by decreasedcholesterol absorption.

14PKK male and female mice (subcongenic for CASA-Rk DNA between D14Mit251 [4 cM] and D14Mit233 [19.5 cM]) displayed significantly decreased plasma plant sterol levels and decreased cholesterol absorption compared to C57BL/6J controls. Subcongenic 14PKK male and female animals also display increased biliary sterol secretion and elevated bile-to-plasma plant sterol ratios compared to controls. Food consumption did not differ between 14PKK and C57BL/6J.

14DKK male and female mice (subcongenic for CASA/Rk DNA between D14Mit259 [19.5 cM] and D14Mit267 [60 cM]) displayed significantly decreased plasma plant sterol levels and decreased cholesterol absorption compared to C57BL/6J controls. Food consumption did not differ between 14DKK and C57BL/6J. However, female 14DKK mice have decreased absolute biliary plant sterol concentrations and bile-to-plasma plant sterol concentration ratios compared to C57BL/7J females.

Authors conclude that at least 2 loci are involved in the Plast1 locus. The proximal portion of the locus (Plast1a) may harbor a gene involved in both decreasing intestinal sterol absorption and increasing biliary sterol secretion. The distal portion of the locus (Plast1b) appears to be involved in decreasing sterol absorption. Other gene-gene effects in the Plast1a-Plast1b interval may explain the sex-dependent effects present in 14KK congenics but not observed in 14PKK or 14DKK subcongenics.

References

• Original: J:116492 Sehayek E, et al., A complex plasma plant sterol locus on mouse chromosome 14 has at least two genes regulating intestinal sterol absorption. J Lipid Res. 2006 Oct;47(10):2291-6
• All: 3 reference(s)