Lysosomal agents inhibit store-operated Ca²⁺ entry

Area of Science:

• Cell Biology
• Molecular Biology
• Physiology

Background:

• Lysosomes are crucial for cellular processes, and their manipulation is key to studying their function.
• Store-operated calcium entry (SOCE) is a vital calcium influx pathway regulated by the endoplasmic reticulum and plasma membrane proteins like Stim1 and Orai.

Purpose of the Study:

• To investigate the unexpected effects of lysosomal manipulation agents on store-operated calcium entry (SOCE).
• To elucidate the molecular mechanisms by which lysosomal agents impact SOCE and Stim1/Orai function.

Main Methods:

• Utilized dipeptides (GPN, L-leucyl-L-leucine methyl ester) to induce lysosomal membrane permeabilization (LMP).
• Employed the K+/H+ ionophore nigericin to alter lysosomal pH.
• Assessed the impact of these agents on SOCE, Stim1 oligomerization, Stim1 activation of Orai, and calcium release from endoplasmic reticulum stores.
• Investigated the effect of the dynamin inhibitor dynasore on GPN-induced inhibition of SOCE.

Main Results:

• Dipeptides (GPN, L-leucyl-L-leucine methyl ester) and nigericin inhibited SOCE by interfering with Stim1 oligomerization and/or Stim1 activation of Orai.
• Lysosomal agents uncoupled endoplasmic reticulum Ca2+-store depletion from SOCE.
• Bafilomycin A1 and lysosomal re-positioning did not affect SOCE.
• The inhibitory effects of GPN on SOCE and Stim1 were reversed by dynasore.

Conclusions:

• Pharmacological manipulation of lysosomes can unexpectedly inhibit SOCE through Stim1-dependent mechanisms.
• Lysosomal agents can disrupt the coordinated function of calcium release and influx pathways.
• These findings highlight a novel crosstalk between lysosomal function and calcium signaling, modulated by dynamin.