Hypoxia accentuates LOX expression via HIF-1, leading to enhanced collagen cross-linking.

<p>(A) Hypoxic exposure increases expression of HIF-1α in the nuclear extract of wild-type mouse hepatocytes. This change is abolished in hepatocytes from <i>Hif1a</i>^<i>-/-</i><i>hep</i> mice. (B) LOX mRNA expression increases in wild-type hepatocytes exposed to hypoxia, but this increase in LOX is not observed in <i>Hif1a</i>^<i>-/-</i><i>hep</i> hepatocytes. (C) When culture media from wild-type hepatocytes is added to collagen, hypoxia causes increased collagen cross-linking and precipitation; this difference is not seen in <i>Hif1a</i>^<i>-/-</i><i>hep</i> hepatocytes. *, p<0.05; ††, p<0.001.</p

Expression of genes involved in fibrosis, hepatic lipid metabolism, and inflammation/apoptosis.

<p>Expression of genes involved in fibrosis, hepatic lipid metabolism, and inflammation/apoptosis.</p

Liver histology and collagen quantification.

<p>(A) Representative liver H&E (top) and Masson’s trichrome stains (bottom) from wild-type (left) and <i>Hif1a</i>^<i>-/-</i><i>hep</i> mice. More fibrosis can be observed in the wild-type mice in the Masson’s trichrome stain. (B) Sirius red stain of collagen in wild-type (left) and <i>Hif1a</i>^<i>-/-</i><i>hep</i> mice (right). (C) Collagen content of all samples by use of hydroxyproline assay. *, p<0.05.</p

Liver hypoxic profile.

<p>(A) Wild-type (left) and <i>Hif1a</i>^<i>-/-</i><i>hep</i> (right) liver tissue was similarly hypoxic after six months on an HTFD, as qualitatively assessed by Hypoxyprobe stain. (B) As expected, HIF-1α protein levels were reduced in <i>Hif1a</i>^<i>-/-</i><i>hep</i> mice. Some HIF-1 activation in <i>Hif1a</i>^<i>-/-</i><i>hep</i> mouse liver tissue likely remains due to incomplete gene knockout, and preserved HIF-1α in non-hepatocyte cell types. †, p<0.005.</p

Metabolic characteristics of wild-type and <i>Hif1a</i>^<i>-/-</i><i>hep</i> mice.

<p>(A) Hepatocyte knockout of HIF-1α was confirmed by quantifying HIF-1α mRNA expression from the nuclear extract of isolated hepatocytes. (B) Body weight (top) and food intake (bottom) over experiment duration. (C) IPGTT (top) and ITT (bottom) at time of sacrifice. †, p<0.005.</p

Mouse Histologic Characteristics.

<p>Mouse Histologic Characteristics.</p