Effect of serum from patients with Acute Intermittent Porphyria ON delta-Aminolevulinic acid synthase 1 protein expression in C3A hepatoma cells.

MORA SANDRA; OLIVERI LEDA; PARERA VICTORIA; BUZALEH, ANA MARIA; GEREZ, ESTHER

Mar del Plata

Congreso; LXXI Congreso de la Asociación Argentina de Investigación ClínicaLXX; 2023

Sociedad Argentina de Investigación Clinica

Acute Intermittent Porphyria (AIP) is a hereditary disorder of hemebiosynthesis, characterized by a decreased activity of the enzymeporphobilinogen deaminase, associated with an induced expressionof delta-aminolevulinic acid synthetase 1 (ALA-S1), first enzyme andregulator of this pathway. In vitro investigations performed in ourlaboratory in C3A hepatoma cells, demonstrated that the addition ofhuman serum (HS) to culture medium caused a significant increasein ALA-S1 through Akt/mTOR/4EBP pathway. Based on these results,our aim was to extend the study using AIP patient’s serum(PHS) in order to elucidate the mechanisms underlying the deregulationof ALA-S1 in this pathology. The serums used belonged topatients classified according to symptomatology: Latent (PHS-L),without symptoms; Manifest (PHS-M), at least one attack and biochemicalvalues that returned to normal levels; and Subclinical manifests(PHS-MS), which suffered attack and their biochemical valuesremain elevated. Cells were cultured in low glucose (5 mM) DMEMmedium, 10% fetal bovine serum (FBS). Subsequently, they werestarved of FBS for 18 hours and then incubated for 2 hours with 2%control HS (CHS), PHS-L, PHS-M or PHS-MS. All PSHs caused asignificant increase in ALA-S1 protein levels (45%) and a decreasein its mRNA expression (50%). In the different treatments with PHS,the phosphorylation of Akt (Ser473) was not increased, unlike thatobserved when CHS was used. 4EBP-1 was phosphorylated in alltreatments. According to these results, the protein tyrosine kinasec-Src that activates mTORC1 pathway was also analyzed. It wasfound that c-Src was phosphorylated in PHS groups suggesting thatthis protein would be responsible for the increase in the translationof ALA-S1 by activation of c-Src/mTOR/4EBP-1 independent of Akt/mTOR pathway.