CHARACTERIZATION OF HMG-CoA LYASE ISOFORM CODIFICATED BY HMGCLL1 GENE

ARNEDO MARIA; PIE-JUSTE JUAN; CAMPETELLI ALEXIS; MENAO-GUILÉN SEBASTIÁN; NOELIA MONESTEROLO; SANTANDER VERÓNICA; CASALE CESAR

Villa Giardino. Córdoba.

Congreso; XVI Jornadas Científicas. Sociedad de Biología de Córdoba.; 2007

Acetoacetyl-CoA thiolase and 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase which comprise the HMG-CoA-generating system(s) for hepatic cholesterogenesis and ketogenesis exhibit dual mitochondrial and cytoplasmic localization. In contrast, HMG-CoA lyase (HL), an enzyme unique to the “HMG-CoA cycle” of ketogenesis, appears to be localized in the mitochondrion. The identity of enzymes involved in these processes and their regulation remain unclear. Recently, a HMG-CoA lyase new gene (HMGCLL1) has been cloned in our laboratory. Kinetic analysis showed that the proteic product of HMGCLL1 has a similar behavior to that found in cytosolic fraction of mouse testicle, while HL has a similar kinetic behavior to that found in the same tissue mitochondrion.  To determinate the sub-cellular localization of HMGCLL1 protein, it was fusioned to GFP and expressed in HEK 293 cells. Confocal images showed that HMGCLL1 protein colocalizates with microtubules and calreticulin, a endoplasmic reticulum (ER) membrane protein. Biochemical experiments support the idea that HMGCLL1 protein interacts with ER. These results suggest that the new HMG-CoA lyase, product of HMGCLL1 gene, is a cytoplasmic protein that interacts with ER and that ketone bodies could be sintetized in the cytoplasm