Circulatory lipid transport: lipoprotein assembly and function from an evolutionary perspective.
Level 5 - mechanism / opinion, no new human data
Narrative review of comparative biochemistry and mechanistic non-human models.
PubMed 19130182 · doi:10.1007/s11010-008-0011-3
What was done
The authors reviewed comparative evolutionary research examining the large lipid transfer protein (LLTP) superfamily, specifically comparing mammalian apolipoprotein B (apoB) and low-density lipoprotein receptor (LDLR) pathways with insect apolipophorin II/I (apoLp-II/I), high-density lipophorin (HDLp), and lipophorin receptor (LpR). The review examined structural assembly via microsomal triglyceride transfer protein (MTP), post-translational furin cleavage, endocytic uptake mechanisms, and receptor-ligand complex stability across pH and calcium conditions using wild-type, mutant, and hybrid receptors.
What was found
No quantitative numerical values were reported in the abstract. Qualitatively, insect apoLp-II/I undergoes post-translational furin cleavage to form two non-exchangeable apolipoproteins in HDLp. Unlike mammalian LDL particles that are degraded in lysosomes following LDLR-mediated endocytosis, insect HDLp acts as a reusable lipid shuttle. In endocytic pathways, the HDLp-LpR complex resists dissociation at low endosomal pH and reduced calcium concentrations (mimicked by EDTA), supporting transferrin-like lipoprotein recycling rather than degradation.
Why it matters
The review outlines how circulatory lipid transport mechanisms diverged across animal evolution, contrasting destructive mammalian lipid clearance with efficient, reusable lipoprotein recycling systems in insects.
Limits
This is a narrative review with no primary empirical dataset or quantitative metrics provided in the abstract. Details regarding specific experimental assays, species tested, sample sizes, and statistical variance are absent. Findings from insect physiological models have limited direct clinical application to human lipid pathology.
Cited by
- contradicts Most animal species do not have ApoB and do not require LDL.