Differential effect of combined lipase deficiency (cld/cld) on human hepatic lipase and lipoprotein lipase secretion.

Combined lipase deficiency (cld) is a recessively inherited disorder in mice associated with a deficiency of LPL and hepatic lipase (HL) activity. LPL is synthesized in cld tissues but is retained in the endoplasmic reticulum (ER), whereas mouse HL (mHL) is secreted but inactive. In this study we investigated the effect of cld on the secretion of human HL (hHL) protein mass and activity.

Determinants of human apolipoprotein [a] secretion from mouse hepatocyte cultures.

Efforts to develop an in vitro model system to analyze apolipoprotein [a] (apo[a]) gene transcription, mRNA translation, and protein secretion have been complicated by the limited tissue and species distribution of apo[a] and the presence of regulatory DNA sequences remote from the apo[a] transcription start site. In the current study we examined primary hepatocytes cultured from apo[a] transgenic mice as a model system for analyzing apo[a] biogenesis. Hepatocytes from mice transgenic for a yeast artificial chromosome (YAC) encoding the entire apo[a] gene in its own genomic context (YAC-apo[a] hepatocytes) were unable to maintain apo[a] expression beyond 48 h of culture.

Role of N-linked carbohydrate processing and calnexin in human hepatic lipase secretion.

The addition and endoplasmic reticulum (ER) glucosidase processing of N-linked glycans is essential for the secretion of rat hepatic lipase (HL). Human HL is distinct from rat HL by the presence of four as opposed to two N-linked carbohydrate side chains. We examined the role of N-linked glycosylation and calnexin interaction in human HL secretion from Chinese hamster ovary (CHO) cells stably expressing a human HL cDNA.