Development and Characterization of a Sf-1-Flp Mouse Model

Area of Science:

• Neuroscience
• Genetics
• Endocrinology

Background:

• Genetic tools like Cre-LoxP and Flp-FRT systems are crucial for studying complex biological processes.
• Steroidogenic factor-1 (SF-1) is a key protein expressed in the ventromedial hypothalamic nucleus (VMH), a region involved in regulating complex physiology.

Purpose of the Study:

• To develop and characterize novel Sf-1-Flp mice for precise genetic manipulation of SF-1 neurons.
• To investigate the role of SF-1 neurons in regulating blood glucose and skeletal muscle PGC-1α.
• To determine the necessity of skeletal muscle beta-2 adrenergic receptors (Adrβ2) in SF-1 neuron-mediated physiological responses.

Main Methods:

• Generation of Sf-1-Flp mice by inserting a Flp recombinase sequence into the Sf-1 locus.
• Phenotypic characterization of Sf-1-Flp mice, including fertility and metabolic assessments.
• Optogenetic stimulation using adeno-associated virus (AAV)-bearing Flp-dependent or Cre-dependent channelrhodopsin-2 (ChR2) to activate SF-1 neurons.
• Generation of Sf-1-Flp::SKM^ΔAdrβ2 mice lacking Adrβ2 specifically in skeletal muscle using Cre/LoxP technology.

Main Results:

• Sf-1-Flp mice exhibited normal phenotypes, fertility, and metabolic profiles, with no alteration in Sf-1 mRNA levels.
• Optogenetic activation of SF-1 neurons in Sf-1-Flp mice increased blood glucose and skeletal muscle PGC-1α.
• Activation of SF-1 neurons failed to increase skeletal muscle PGC-1α in Sf-1-Flp::SKM^ΔAdrβ2 mice, highlighting the role of Adrβ2.

Conclusions:

• Sf-1-Flp mice are a valuable genetic tool for studying VMH-regulated physiology.
• SF-1 neuron activation influences blood glucose and skeletal muscle PGC-1α.
• Skeletal muscle Adrβ2 is essential for SF-1 neuron-mediated increases in skeletal muscle PGC-1α.