Aster-dependent nonvesicular transport facilitates dietary cholesterol uptake

Area of Science:

• Cell biology
• Molecular biology
• Physiology

Background:

• Intestinal cholesterol absorption significantly impacts systemic cholesterol levels.
• Niemann-Pick C1 Like 1 (NPC1L1) is known to facilitate dietary cholesterol uptake, but subsequent intracellular transport mechanisms remain unclear.

Purpose of the Study:

• To elucidate the downstream pathway of cholesterol movement following NPC1L1-mediated uptake in enterocytes.
• To identify novel proteins and pathways involved in nonvesicular cholesterol transport.

Main Methods:

• Investigated the role of Aster-B and Aster-C in cholesterol transport using cellular and animal models.
• Assessed the impact of NPC1L1 and Aster deficiency on cholesterol localization and transport.
• Utilized small-molecule inhibitors to target the Aster pathway.

Main Results:

• Aster-B and Aster-C are essential for nonvesicular cholesterol movement from the plasma membrane into enterocytes.
• Loss of NPC1L1 reduces available plasma membrane cholesterol and prevents Aster recruitment.
• Enterocytes lacking Asters exhibit increased plasma membrane cholesterol and depleted endoplasmic reticulum cholesterol.
• Aster-deficient mice demonstrate impaired cholesterol absorption and resistance to diet-induced hypercholesterolemia.

Conclusions:

• The Aster pathway is a critical regulator of intracellular cholesterol transport in enterocytes.
• This pathway represents a novel and pharmacologically targetable mechanism for modulating dietary cholesterol absorption.
• Findings provide new insights into cholesterol homeostasis and potential therapeutic strategies for hypercholesterolemia.