Table 1 ‘Find-me’ signals and possible supplementary actions they can have during apoptotic cell clearance

From: Do not let death do us part: ‘find-me’ signals in communication between dying cells and the phagocytes

‘Find-me’ signal

Discovery context (cell types)

In vivo

Supplementary actions

Comments

LPC

MCF7caspase 3

—

DC maturation, ↑MIP-2, TNFα, IFNγ release, ↑H2O2, superoxide release from neutrophils, ↓HMGB1 release, T-cell and NK cell chemotaxis, ↑ B-cell Ab release

LPC species and receptors may be important for specific functions during cell clearance

S1P

Jurkat Cells

—

Anti-apoptotic, lymphocyte migration, ↓TNFα, IL-6 and IL-12 production, polarization to M2 macrophage, ↑IL-10 and PGE2, suppress T-cell proliferation and activation responses

Unknown receptor, (SIP1/SIP3 have been implicated in migration)

ABCA1 regulates lysophospholipid release during apoptosis (may be S1P)

FKN

Burkitt lymphoma cells

Activated CD19-lymphocytes

✓

Chemotractant for NK cells, T cells, B cells, protective effects in CNS, ↑phagocytosis

Unknown protease for 60-kDa fragment generation

Many auxiliary effects are a consequence of 90-kDa form

ATP/UTP

Thymocytes

Jurkat Cells

MCF7caspase3

✓

Inflammatory at high concentrations and anti-inflammatory at low concentrations, ↑phagocytosis of microglia and macrophages through P2Y6 and P2X1/3, respectively

Effects of ATP metabolites on phagocytes are unclear

Other factors released by Panx1 is also not known

RP S19

AsPC-1

HL-60

NIH3T3

RA synovial tissue

✓

Inhibit neutrophil chemotaxis, responsible for adaptive immune response toward apoptotic cells, pro-apoptotic effects on non-macrophages

Chemotactic factor was not released until 24 h after apoptosis induction

Release during physiological apoptotic death not examined

EMAPII

32D

Meth A cells

MEFs

—

↑Myeloperoxidase activity in neutrophils, neutrophil chemotaxis, upregulation of TNF-R1, pro-apoptotic effects on endothelial cells and lymphocytes, activation of monocytes

Released 10–12 h after apoptosis

Unknown receptor on monocytes

Pro-EMAPII (p43) can also be secreted (non-apoptotic) and has pro-inflammatory properties

TryRS

U-937

—

Pro-angiogenic, C-terminal product-stimulated pro-inflammatory and chemotactic effects similar to EMAPII, N-terminal fragment only induced migration in neutrophils

C-terminal fragment shares homology with EMAPII

Released 12 h after apoptosis

  1. The contexts in which these signals were discovered and the different cell types that are known to release them are indicated. The table also describes a list of some of the additional signaling capabilities that these mediators are capable of eliciting, as well as additional information that is not known or debated in the field.
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