Forsøksdyr: Plin transgenic mice - Breeding and diet interventions

Godkjenningsdato 23.11.2020

Godkjenningsperiode 01.01.2021-31.12.2024

I. Purpose
Cells in humans may synthesize and store intracellular lipid droplets (LDs). LDs have multiple biological roles, e.g. as efficient reservoirs of energy and substrates for membrane and steroid hormone synthesis. Proteins in the perilipin family (perilipin 1-5, gene names Plin1-5) are abundant on the LD surface. Plins are important for regulation of LD degradation, but their individual biological roles are poorly understood. The purpose of this project is to understand the biological role of each Plin by systematic phenotypic analysis of normal and Plin1-5 transgenic mice.
According to §10, the purpose is: a) Basal research.

II. Expected distress
Mice with single mutation of Plin genes give offspring with normal Mendalian distribution with no observed phenotypic abnormalities affecting their quality of life. Double transgenic (Plin2-/-3-/-, Plin2-/-5-/-) may have reduced weights. Transgenic mice overexpressing Flpe and Cre show no signs of phenotypic abnormality.
The genetic modifications are defined as mild for single transgenic, but moderate for double transgenic models. The experimental procedures described under this protocol are categorized as mild or moderate. The whole animal proposal is rated as “Moderate”, but experiments for most mice are expected to be mild.

III. Expected benefits
The obtained results will increase our understanding of the perilipin proteins and their role for LD accumulation in various cell types in mice. The murine Plin genes share high sequence homology with humans. Experimental results obtained in mice will therefore in large be representative for both species. Increased understanding of LD might reveal new molecular mechanisms that can be targeted with drugs to treat various lipid diseases.

IV. Number and type of animals
The proposal includes mice required for back-crossing of lines, breeding to generate parents for experimental animals, and experimental animals. Males and female mice (Plin1-/-, Plin2-/-, Plin3-/-, Plin4-/-, and Plin5-/-, combinations of these and controls,) will foremost be used before 16 weeks of age. A lower number of mice may be housed up to 18 mounts for phenotypic age-characterization. Breeders will be replaced before 1 year of age.
In total it is applied for 750 mice pr year x 4 years = 3000 mice.

V. Adherence to the 3Rs
Supplemental experiments will be performed in cell culture whenever possible; but whole animals are needed to understand the physiological role of the various Plin proteins. The laboratory mouse is a good model to study gene functions and human disease; with a physiology similar to humans and well-established methods for genetic modifications. Mice will be used for collection of organs, tissues and cells; sampling that would not be possible with human research subjects. Alternatives to animal use therefore do not exist.

To reduce animal use, all lines are back-crossed to congenic strains (>N10, reduces experimental variation), and experimental animals will be generated from WT/WT and KO/KO breeding pairs, with genetic distance less than F10. To ensure efficient use, mice born will be subjected to a set of experimental procedures described in this application, or transferred to other existing or later FOTS protocols.