Dictyostelium differentiation-inducing factor-1 binds to mitochondrial malate dehydrogenase and inhibits its activity

Area of Science:

• Biochemistry
• Cell Biology
• Molecular Pharmacology

Background:

• Differentiation-inducing factors (DIFs) from Dictyostelium discoideum inhibit cancer cell proliferation via Wnt/beta-catenin signaling.
• The specific molecular targets of DIFs responsible for their anti-proliferative effects remain unidentified.

Purpose of the Study:

• To identify DIF target molecules involved in anti-proliferative effects.
• To investigate the role of mitochondrial malate dehydrogenase (mMDH) as a DIF target.

Main Methods:

• Synthesis of DIF-1-tethered resins for target molecule identification.
• In vitro binding assays with DIF-1 and analogs against mMDH and cytoplasmic MDH.
• Enzymatic activity assays of mMDH in the presence of DIF analogs.
• Analysis of ATP content and HeLa cell proliferation upon treatment with DIF analogs.

Main Results:

• Mitochondrial malate dehydrogenase (mMDH) was identified as a DIF-1 binding molecule.
• DIF-1 and 2-MIDIF-1 inhibited mMDH enzymatic activity, but not cytoplasmic MDH.
• DIF-1 and 2-MIDIF-1 reduced ATP content and inhibited HeLa cell proliferation.
• These effects were independent of Wnt/beta-catenin signaling pathway suppression.

Conclusions:

• Inhibition of mMDH activity by DIF-1 and 2-MIDIF-1 is a potential mechanism for inducing anti-proliferative effects.
• This mechanism impacts cellular energy production, leading to reduced proliferation.
• DIF-1's anti-proliferative action can occur independently of Wnt/beta-catenin pathway modulation.