Inhibition of the ubiquitin-proteasome system reduces the abundance of pyruvate dehydrogenase kinase 1 in cultured myotubes

Blaž Kociper (Avtor), Nives Škorja (Avtor), Ivana Ogrizek (Avtor), Katarina Miš (Avtor), Sergej Pirkmajer (Avtor)

Povzetek

Pyruvate dehydrogenase kinase (PDK), which phosphorylates the pyruvate dehydrogenase complex, regulates glucose metabolism in skeletal muscle. PDK1, an isozyme whose expression is controlled by hypoxia-inducible factor-1α (HIF-1α), is thought to play a role in muscle adaptation to hypoxia. While transcriptional upregulation of PDK1 by HIF-1α is well characterised, mechanisms controlling proteolysis of PDK1 in skeletal muscle have not been thoroughly investigated. Proteasome inhibitor MG132 paradoxically reduced the abundance of PDK1 in human cancer cells and rat L6 myotubes, suggesting that MG132 might direct PDK1 towards autophagic degradation. The objectives of our current study were to determine (1) whether MG132 suppresses PDK1 levels in primary human myotubes, (2) whether chloroquine, an inhibitor of autophagy, prevents MG132-induced suppression of PDK1 in L6 myotubes, and (3) whether PYR-41, an inhibitor of ubiquitination, suppresses PDK1 in L6 myotubes. Using qPCR and/or immunoblotting, we found that despite markedly upregulating HIF-1α protein, MG132 did not alter the PDK1 expression in cultured primary human myotubes, while it suppressed both PDK1 mRNA and protein in L6 myotubes. The PDK1 levels in L6 myotubes were suppressed also during co-treatment with chloroquine and MG132. PYR-41 markedly increased the abundance of HIF-1α in primary human and L6 myotubes, while reducing the abundance of PDK1. In L6 myotubes treated with PYR-41, chloroquine increased the abundance of the epidermal growth factor receptor, but did not prevent the suppression of PDK1. Collectively, our results suggest that cultured myotubes degrade PDK1 via a pathway that cannot be inhibited by MG132, PYR-41, and/or chloroquine.

Ključne besede

chloroquine;hypoxia-inducible factor-1α (HIF-1α);MG132;myotubes;PYR-41;pyruvate dehydrogenase kinase 1 (PDK1);

Podatki

Jezik:	Angleški jezik
Leto izida:	2024
Tipologija:	1.01 - Izvirni znanstveni članek
Organizacija:	UL MF - Medicinska fakulteta
UDK:	616-092
COBISS:	203573251
ISSN:	1573-2657
Št. ogledov:	22
Št. prenosov:	4
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Slovenski jezik
Sekundarne ključne besede:	klorokin;hipoksijsko inducibilni faktor-1α (HIF-1α);miocevke;piruvat dehidrogenaza kinaza 1 (PDK1);
Vrsta dela (COBISS):	Članek v reviji
Strani:	str. 1-15
Letnik:	ǂVol. ǂ
Zvezek:	ǂiss. ǂ[ahead of print]
Čas izdaje:	2024
DOI:	10.1007/s10974-024-09679-3
ID:	24784608