p53_vezio_metabolizmas.Rmd

# p53 reguliuoja mitochondrijų kvėpavimą

Straipsnis: 
Matoba S, Kang JG, Patino WD et al. (2006) p53 regulates mitochondrial respiration. Science 312, 1650–1653.
Klausimai:
1.	Kokiu būdu eukariotinė ir vėžinė ląstelės gamina ATP?
2.	Kodėl tyrėjai nusprendė tirti ryšį tarp p53 ir Warburg efekto?
so widespread, an explanation for this phenomenon
must lie, at least in part, in a pathway that is
commonly altered in cancer cells. We therefore
examined whether alteration of p53, the gene
most commonlymutated in human cancer,might
affect COX complex assembly and activity.
3.	Kokią koreliaciją tyrėjai nustatė tarp p53 ir ATP gamybos būdo?
The ratio of ATP
produced by glycolysis versus ATP produced
by aerobic respiration increased with p53 deficiency:
p53þ/þ, 0.81 T 0.12; p53þ/j, 1.04 T
0.20; and p53j/j, 1.72 T 0.16 (Fig. 1B).
4.	Tyrėjai taip pat lygino sveikas peles ir p53 homozigotines mutantes. Ką jie nustatė? Ar tai atitinka prieš tai nustatytus ATP gamybos skirtumus?
The general appearance
and behavior of p53þ/þ and p53j/j mice were
indistinguishable, as previously observed (12),
and their body mass and composition were essentially
identical (Fig. 1C). However, the endurance
of p53j/j mice was reduced, as measured
by a swimming stress test (Fig. 1D) (13).
5.	Kokią hipotezę autoriai iškėlė, bandydami paaiškinti p53 mutacijos ryšį su sumažėjusiu aerobiniu kvėpavimu? Kaip jie sugalvojo šią hipotezę?
SCO2 is required for the assembly of
mitochondrial DNA-encoded COX II subunit
(MTCO2 gene) into the COX complex, and inactivating
mutations of this gene in humans
result in fatal cardioencephalomyopathy due to
aerobic respiratory failure (17). To confirm that SCO2 transcription is directly
transactivated by p53, we used human
colon cancer DLD1 cell lines with either inducible
wild-type (WT) or mutant (MUT) p53 for
expression studies (18). SCO2 mRNA expression
increased within 3 to 18 hours of induced
WT p53 expression but was not affected by
mutant p53 (Fig. 2A and fig. S2). We also
measured the mRNA expression level of SCO1,
another COX assembly factor. SCO1 mRNA
expression remained unchanged with induced
p53 expression, serving as a negative control
and demonstrating the specificity of the observed
SCO2 mRNA increase
6.	Kas yra liuciferazės reporteris ir kaip jis buvo panaudotas 2B paveikslėlyje? Kokie yra tokios analizės privalumai ir trūkumai?
We tested this
hypothesis by cloning a È1.1-kb fragment of
the SCO2 gene containing the p53-binding sequence
into a luciferase reporter plasmid.
7.	Kokie papildomi tyrimai ir duomenys sustiprintų išvadą, jog p53 reguliuoja ląstelinį kvėpavimą per SCO2?
8.	Kodėl šis tyrimas ir jo išvados yra svarbios?
The direct regulation of aerobic respiration
by p53 has important implications for understanding
tumorigenesis. To date, much of the
research on cellular processes driven by oncogenes
and tumor suppressor genes has focused
on the regulation of cell birth and death
(1). Our study identifies a direct transcriptional
target of p53 that modulates aerobic respiration
and, by its haploinsufficiency, recapitulates the
Warburg effect. It also defines a genetic pathway,
not involving cell cycle regulation, by
which the inactivation of p53 may promote tumorigenesis
by decreasing cellular dependence
on oxygen, potentially permitting growth in more hypoxic environments.
Given the
mounting evidence supporting a role for metabolism
and oxidative stress in aging (30, 31), the
functional relationship between p53 and the
COX complex assembly may underlie some aspects
of organismal aging. In filamentous fungus,
the genetic disruption of COX II markedly increases life-span.