Generation and validation of a conditional knockout mouse model for desmosterolosis

Area of Science:

• Biochemistry
• Genetics
• Animal Models

Background:

• 3β-hydroxysterol-Δ24 reductase (DHCR24) is crucial for cholesterol synthesis.
• DHCR24 deficiency causes desmosterolosis, a rare disease with congenital anomalies.
• Previous global knockout mice models have limited utility due to early lethality.

Purpose of the Study:

• To develop and validate a conditional knockout mouse model for DHCR24.
• To investigate the consequences of liver-specific DHCR24 loss.
• To explore DHCR24's role in sterol homeostasis and potential compensatory mechanisms.

Main Methods:

• Generation of a conditional knockout mouse line (Dhcr24^flx/flx).
• Creation of a liver-specific knockout by crossing with Alb-Cre mice (Dhcr24^{flx/flx,Alb-Cre}).
• Analysis of desmosterol levels, liver function, gene expression, and sterol excretion.

Main Results:

• Dhcr24^{flx/flx,Alb-Cre} mice exhibit normal growth and fertility.
• Significant accumulation of desmosterol in plasma and liver was observed.
• Hepatic architecture, sterol gene expression, and lipoprotein secretion remained unchanged.
• Increased desmosterol in bile and stool suggests hepatobiliary compensation for sterol homeostasis.

Conclusions:

• The conditional KO mouse model enables the study of postnatal DHCR24 loss.
• Liver-specific DHCR24 deficiency leads to desmosterol accumulation without apparent liver damage.
• Hepatobiliary secretion may play a compensatory role in maintaining sterol balance.
• This model is valuable for investigating DHCR24's function in development and adulthood.