Poly(ADP-ribose) polymerase 1 (PARP-1) and p53 are two key proteins in the DNA-damage response. Although PARP-1 is known to poly(ADP-ribosyl)ate p53, the role of this modification remains elusive. Here, we identify the major poly(ADP-ribosyl)ated sites of p53 by PARP-1 and find that PARP-1-mediated poly(ADP-ribosyl)ation blocks the interaction between p53 and the nuclear export receptor Crm1, resulting in nuclear accumulation of p53. These findings molecularly link PARP-1 and p53 in the DNA-damage response, providing the mechanism for how p53 accumulates in the nucleus in response to DNA damage. PARP-1 becomes super-activated by binding to damaged DNA, which in turn poly(ADP-ribosyl)ates p53. The nuclear export machinery is unable to target poly(ADP-ribosyl)ated p53, promoting accumulation of p53 in the nucleus where p53 exerts its transactivational function. 相似文献
Drosophila germline stem cells are regulated by the somatic microenvironment, or "niche," which ensures that the stem cells can both self-renew and produce functional gametes throughout adult life. However, despite its prime importance, little is known about how niche formation is regulated during gonadal development. Here, we demonstrate that a receptor tyrosine kinase, Sevenless (Sev), is required to ensure that the niche develops in the anterior region of the male embryonic gonads. Sev is expressed in somatic cells within the posterior region of the gonads. Sev is activated by a ligand, Bride of sevenless (Boss), which is expressed by the germline, to prevent ectopic niche differentiation in the posterior gonadal somatic cells. Thus, we propose that signal transduction from germline to soma restricts expansion of the germline-stem-cell niche in the gonads. 相似文献
Applied Biochemistry and Microbiology - Pectin is a polymer commonly found in the fruit peels. Pectin-mediated gold nanoparticles (AuNPs) were fabricated and characterized by spectroscopic and... 相似文献
Cyclic electron transport (CET) is an attractive hypothesis for regulating photosynthetic electron transport and producing the additional ATP in oxygenic phototrophs. The concept of CET has been established in the last decades, and it is proposed to function in the progenitor of oxygenic photosynthesis, cyanobacteria. The in vivo activity of CET is frequently evaluated either from the redox state of the reaction center chlorophyll in photosystem (PS) I, P700, in the absence of PSII activity or by comparing PSI and PSII activities through the P700 redox state and chlorophyll fluorescence, respectively. The evaluation of CET activity, however, is complicated especially in cyanobacteria, where CET shares the intersystem chain, including plastoquinone, cytochrome b6/f complex, plastocyanin, and cytochrome c6, with photosynthetic linear electron transport (LET) and respiratory electron transport (RET). Here we sought to distinguish the in vivo electron transport rates in RET and CET in the cyanobacterium Synechocystis sp. PCC 6803. The reduction rate of oxidized P700 (P700+) decreased to less than 10% when PSII was inhibited, indicating that PSII is the dominant electron source to PSI but P700+ is also reduced by electrons derived from other sources. The oxidative pentose phosphate (OPP) pathway functions as the dominant electron source for RET, which was found to be inhibited by glycolaldehyde (GA). In the condition where the OPP pathway and respiratory terminal oxidases were inhibited by GA and KCN, the P700+ reduction rate was less than 1% of that without any inhibitors. This study indicate that the electron transport to PSI when PSII is inhibited is dominantly derived from the OPP pathway in Synechocystis sp. PCC 6803.
Neurochemical Research - Methamphetamine (METH), an illicit psycho-stimulant, is widely known as an addictive drug that may cause neurotoxic effects. Previous researches on METH abuse have mainly... 相似文献