Abstract
The metabolism of fatty acids represents an important energy source for early embryonic development. Our knowledge of the molecular basis that regulate this metabolism is very poor. In this study we have analysed the pattern of expression ofCpt-1 andCpt-2 genes, that encode the enzymes CPT-1 and CPT-2, which play a role in long chain fatty acids transport inside the mitochondria. The data obtained from the RT-PCR analysis show a rapid reduction in the number of transcripts from antral oocyte to ovulated MII oocyte and a significant difference between the expression profiles ofCpt-1 andCpt-2 genes during preimplantation development.Cpt-1 is first temporarily expressed at the G2 phase of 2-cell embryo, it disappears at the 4-cell stage and reappears consistently between the 8-cell and morula stage;Cpt-2 is expressed from the MII oocyte, decreases to very low level at the 8-cell stage and is actively transcribed from morula, where it abruptly increases its expression to reach its maximum at the blastocyst stage. Interestingly, the high expression of bothCpt-1 andCpt-2 at the morula stage is correlated with an increasing profile of oxygen uptake and fatty acid oxidation found at this stage of development. Furthermore, this rise of transcription is concomitant with other important epigenetic changes occurring prior to embryo cavitation and involving a reorganisation of chromatin structure and DNA methylation.
Riassunto
Il metabolismo degli acidi grassi rappresenta una importante fonte di energia per l’embrione nelle prime fasi di sviluppo preimpianto. Le conoscenze delle basi molecolari che regolano questo metabolismo sono molto scarse. In questo studio abbiamo analizzato il profilo di espressione dei geniCpt-1 eCpt-2, che traducono per gli enzimi CPT-1 e CPT-2, coinvolti nel trasporto degli acidi grassi a lunga catena all’interno dei mitocondri. I dati, ottenuti dall’analisi molecolare mediante la tecnica della RT-PCR, mostrano una notevole riduzione del numero dei trascritti tra oocita antrale e oocita ovulato in MII, ed una notevole differenza tra i profili di espressione diCpt-1 eCpt-2 durante lo sviluppo preimpianto.Cpt-1 risulta essere temporaneamente espresso allo stadio di embrione a 2 cellule, è silente nell’embrione a 4 cellule e ricompare tra l’embrione a 8 cellule e lo stadio di morula;Cpt-2 è invece già espresso nell’oocita in MII, la sua espressione si riduce gradualmente fino a bassi livelli nell’embrione a 4 cellule, per poi tornare a essere attivamente trascritto nella morula, dove il numero di trascritti incrementa notevolmente fino a raggiungere il picco di espressione nella blastocisti. Significativo è il fatto che l’intensificazione dell’espressione genica diCpt-1 eCpt-2 allo stadio di morula è correlata con l’incremento nel consumo di ossigeno legato alla β-ossidazione degli acidi grassi in questo stesso stadio di sviluppo. Inoltre, questo aumento è concomitante con importanti fenomeni epigenetici che precedono la cavitazione dell’embrione ed implicano la riorganizzazione della struttura della cromatina e la metilazione del DNA.
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Nella seduta del 14 febbraio 2003.
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Garagna, S., Gentile, L., Merico, V. et al. Expression of Carnitine Palmitoyl-Transferase 1 and 2 during mouse preimplantation development. Rend. Fis. Acc. Lincei 14, 217–229 (2003). https://doi.org/10.1007/BF02904525
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DOI: https://doi.org/10.1007/BF02904525