Dinucleoside polyphosphates-friend or foe?

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Dinucleoside polyphosphates, including diadenosine 5 ,5"-P(1), P(4)-tetraphosphate (Ap4A) and diadenosine 5 ,5"-P(1), P(3)-triphosphate (Ap3A), have been known for over 30 years.
• Their precise biological functions remain largely undetermined, presenting a dichotomy of potential signaling roles versus toxic byproduct status.

Purpose of the Study:

• To review the occurrence, synthesis, degradation, and proposed functions of dinucleoside polyphosphates.
• To present new data and recent evidence supporting roles for Ap3A and Ap4A in cellular fate determination.
• To explore hypotheses regarding Ap4A in DNA damage checkpoints and Ap3A/pFhit in tumor suppression.

Main Methods:

• Literature review of existing research on dinucleoside polyphosphates.
• Presentation of novel data and recent experimental evidence.
• Formulation of hypotheses based on current findings.

Main Results:

• Ap3A and Ap4A are implicated in cellular processes such as proliferation, quiescence, differentiation, and apoptosis.
• Ap4A may play a role in the intra-S phase DNA damage checkpoint.
• Ap3A and the pFhit protein are hypothesized to be involved in tumor suppression.

Conclusions:

• The dual "friend" (signaling) and "foe" (toxic) roles of dinucleoside polyphosphates are not mutually exclusive.
• The cellular context and concentration-dependent effects determine whether these molecules act beneficially or detrimentally.
• Further research is warranted to fully elucidate the complex functions of Ap3A and Ap4A in cellular regulation.