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RASSF4 controls SOCE and ER-PM junctions through regulation of PI(4,5)P2

Yu-Ju Chen1, Chi-Lun Chang1, Wan-Ru Lee1

  • 1Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX.

The Journal of Cell Biology
|June 11, 2017
PubMed

Insights

RAS association domain family 4 (RASSF4) regulates calcium signaling by controlling ER-PM junctions and store-operated calcium entry (SOCE). This involves RASSF4

Area of Science:

  • Cellular Biology
  • Molecular Biology
  • Calcium Signaling

Background:

  • RAS association domain family 4 (RASSF4) is known for its roles in tumorigenesis and Hippo pathway regulation.
  • Store-operated calcium entry (SOCE) is a critical calcium signaling mechanism involving calcium flux into the cell.
  • Endoplasmic reticulum (ER) and plasma membrane (PM) junctions are vital for cellular communication and calcium homeostasis.

Purpose of the Study:

  • To elucidate novel functional roles of RASSF4 in cellular signaling pathways.
  • To investigate the involvement of RASSF4 in the regulation of store-operated calcium entry (SOCE).
  • To understand the molecular mechanisms by which RASSF4 influences ER-PM junctions and associated proteins.

Main Methods:

  • Investigated RASSF4's effect on the translocation of stromal interaction molecule 1 (STIM1) to ER-PM junctions.
  • Assessed RASSF4's role in the formation and tethering function of ER-PM junctions, including E-Syt2 and E-Syt3.
  • Analyzed changes in plasma membrane phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2) levels in RASSF4-knockdown cells.
  • Examined the interaction between RASSF4 and adenosine diphosphate ribosylation factor 6 (ARF6) and its impact on PIP5Ks activity.

Main Results:

  • RASSF4 was found to regulate SOCE by influencing STIM1 translocation to ER-PM junctions.
  • RASSF4 modulates ER-PM junction formation and the function of ER-PM tethers like E-Syt2 and E-Syt3.
  • Knockdown of RASSF4 led to reduced steady-state PI[4,5]P2 levels at the PM.
  • RASSF4 interacts with and regulates ARF6 activity, impacting PIP5Ks and subsequent PI[4,5]P2 production.

Conclusions:

  • RASSF4 plays a significant role in regulating SOCE and ER-PM junctions.
  • The study identifies an ARF6-dependent pathway through which RASSF4 controls PM PI[4,5]P2 levels.
  • These findings highlight RASSF4 as a key regulator of fundamental cellular processes involving calcium signaling and membrane dynamics.

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