Apolipoprotein A-II is catabolized in the kidney as a function of its plasma concentration.

We investigated in vivo catabolism of apolipoprotein A-II (apo A-II), a major determinant of plasma HDL levels. Like apoA-I, murine apoA-II (mapoA-II) and human apoA-II (hapoA-II) were reabsorbed in the first segment of kidney proximal tubules of control and hapoA-II-transgenic mice, respectively. ApoA-II colocalized in brush border membranes with cubilin and megalin (the apoA-I receptor and coreceptor, respectively), with mapoA-I in intracellular vesicles of tubular epithelial cells, and was targeted to lysosomes, suggestive of degradation.

Restriction of apolipoprotein A-IV gene expression to the intestine villus depends on a hormone-responsive element and parallels differential expression of the hepatic nuclear factor 4alpha and gamma isoforms.

The apoA-I/C-III/A-IV gene cluster, like most intestine-specific genes, displays a specific pattern of expression along the intestinal cephalocaudal and crypt-to-villus axes. We have shown that this specific pattern of expression requires the distal apoA-IV promoter and the apoC-III enhancer. Using a new set of transgenic mice, we demonstrate here that the restriction of apoA-IV gene transcription to villus enterocytes requires a hormone-responsive element (HRE) located within the apoA-IV distal promoter.

Fibre-type distribution and subcellular localisation of alpha and beta enolase in mouse striated muscle.

Enolase is a dimeric glycolytic enzyme exhibiting tissue specific isoforms. During ontogenesis, a transition occurs from the embryonic alphaalpha towards the specific alphabeta, and betabeta isoforms in striated muscle. Immunocytochemical analyses on transverse sections of adult mouse gastrocnemius muscle, allowed us to compare the expression of alpha and beta subunits to that of myosin heavy chain (MHC) isoforms.