News

News

Aug 2020: Chi-Lun has a new position

Congratulations of Chi-Lun's new position in the Department of Cell and Molecular Biology at St. Jude Children's Research Hospital! Best wishes for your new job!

 

July 2020: Hannes joins the Liou lab

Hannes is joining the Liou lab as a graduate student in the Cell and Molecular Biology Program. Welcome Hannes!

 

July 2020: Carlo is a trainee of cancer biology T32

Congratulations to Carlo for being selected as a trainee on the NCI Cancer Biology T32 grant.

 

Feb 2020: Yu-Ju has a new position

Congratulations of Yu-Ju's new position at Pfizer! Best wishes for your new job!

 

May 2019: Carlo receives a poster award

Congratulations to Carlo for receiving the 2nd place award of poster competition at the Physiology Departmental Retreat!

 

 Nov 2018: GFP-MAPPER is available at Addgene

Liou Lab has deposited GFP-MAPPER to Addgene for easy access to all researchers.

 

July 2018: Ting-Sung receives his Ph.D.

Congratulations to Ting-Sung for obtaining his Ph.D. in Molecular Biophysics. Good luck in the Tagliabracci lab!

 
May 2018: Yu-Ju gives a talk at the Physiology Departmental Retreat.

Congratulations to Yu-Ju for being selected to give a talk at the Physiology Departmental Retreat!

 

May 2018: Ting-Sung and Wan-Ru receive a poster award.

Congratulations to Ting-Sung and Wan-Ru for receiving a poster award at the Physiology Departmental Retreat!

 

March 2018: Chi-Lun’s paper is published in Journal of Cell Biology.

 

EB1 binding restricts STIM1 translocation to ER–PM junctions and regulates store-operated Ca2+ entry

The endoplasmic reticulum (ER) Ca2+ sensor STIM1 forms oligomers and translocates to ER–plasma membrane (PM) junctions to activate store-operated Ca2+ entry (SOCE) after ER Ca2+ depletion. STIM1 also interacts with EB1 and dynamically tracks microtubule (MT) plus ends. Nevertheless, the role of STIM1–EB1 interaction in regulating SOCE remains unresolved. Using live-cell imaging combined with a synthetic construct approach, we found that EB1 binding constitutes a trapping mechanism restricting STIM1 targeting to ER–PM junctions. We further showed that STIM1 oligomers retain EB1 binding ability in ER Ca2+-depleted cells. By trapping STIM1 molecules at dynamic contacts between the ER and MT plus ends, EB1 binding delayed STIM1 translocation to ER–PM junctions during ER Ca2+ depletion and prevented excess SOCE and ER Ca2+ overload. Our study suggests that STIM1–EB1 interaction shapes the kinetics and amplitude of local SOCE in cellular regions with growing MTs and contributes to spatiotemporal regulation of Ca2+ signaling crucial for cellular functions and homeostasis.

 

March 2018: Jen is promoted to Associated Professor with Tenure.

 

December 2017: Ting-Sung gives a talk at the ASCB meeting.

Congratulations to Ting-Sung for being selected to give a talk on “Spatial organization of ER-PM junctions revealed by super- and high-resolution imaging”, in the Minisymposium entitled “Organelle Morphogenesis, Targeting, and Distribution” under the topic Organelles and Membrane Dynamics, at the 2017 American Society for Cell Biology (ASCB) Annual meeting in Philadelphia, PA!

 

November 2017: Ting-Sung receives the GSO Travel Award.

Congratulations to Ting-Sung for receiving the UT Southwestern Graduate Student Organization (GSO) Travel Award. He will use the fund to travel to the ASCB meeting in Philadelphia in December!

 

November 2017: Yu-Ju gives a talk at the Cell and Molecular Biology Retreat.

Congratulations to Yu-Ju for being selected to give a talk at the annual retreat of the Cell and Molecular Biology Graduate Program of UT Southwestern!

 

September 2017: Ting-Sung’s paper is published in the Special Issue on Quantitative Cell Biology of Molecular Biology of the Cell.

 

Cortical actin contributes to spatial organization of ER–PM junctions

 

Endoplasmic reticulum–plasma membrane (ER–PM) junctions mediate crucial activities ranging from Ca2+ signaling to lipid metabolism. Spatial organization of ER–PM junctions may modulate the extent and location of these cellular activities. However, the morphology and distribution of ER–PM junctions are not well characterized. Using photoactivated localization microscopy (PALM), we reveal that the contact area of single ER–PM junctions is mainly oblong with the dimensions of ∼120 nm × ∼80 nm in HeLa cells. Using total internal reflection fluorescence (TIRF) microscopy and structure illumination microscopy (SIM), we show that cortical actin contributes to spatial distribution and stability of ER–PM junctions. Further functional assays suggest that intact F-actin architecture is required for phosphatidylinositol 4,5-bisphosphate homeostasis mediated by Nir2 at ER–PM junctions. Together, our study provides quantitative information on spatial organization of ER–PM junctions that is in part regulated by F-actin. We envision that functions of ER–PM junctions can be differentially regulated through dynamic actin remodeling during cellular processes.

 

August 2017: Carlo is elected as the GSO President.

Congratulations to Carlo for being elected as the President of the Graduate Student Organization (GSO) at UT Southwestern! 

 

June 2017: Yu-Ju’s paper is published in Journal of Cell Biology.

 

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

RAS association domain family 4 (RASSF4) is involved in tumorigenesis and regulation of the Hippo pathway. In this study, we identify new functional roles of RASSF4. First, we discovered that RASSF4 regulates store-operated Ca2+ entry (SOCE), a fundamental Ca2+ signaling mechanism, by affecting the translocation of the endoplasmic reticulum (ER) Ca2+ sensor stromal interaction molecule 1 (STIM1) to ER–plasma membrane (PM) junctions. It was further revealed that RASSF4 regulates the formation of ER–PM junctions and the ER–PM tethering function of extended synaptotagmins E-Syt2 and E-Syt3. Moreover, steady-state PM phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2) levels, important for localization of STIM1 and E-Syts at ER–PM junctions, were reduced in RASSF4-knockdown cells. Furthermore, we demonstrated that RASSF4 interacts with and regulates the activity of adenosine diphosphate ribosylation factor 6 (ARF6), a small G protein and upstream regulator of type I phosphatidylinositol phosphate kinases (PIP5Ks) and PM PI(4,5)P2 levels. Overall, our study suggests that RASSF4 controls SOCE and ER–PM junctions through ARF6-dependent regulation of PM PI(4,5)P2 levels, pivotal for a variety of physiological processes.

 

December 2016: Yu-Ju gives a talk at the ASCB meeting.

Congratulations to Yu-Ju for being selected to give a talk on “RASSF4 regulates PIP2 and formation of ER-PM junctions”, in the Minisymposium entitled “Organelle Contact Sites and Biogenesis” under the topic Organelles and Spatial Organization of the Cell, at the 2016 American Society for Cell Biology (ASCB) Annual meeting in San Francisco, CA!

 

September 2016: Yu-Ju receives the ASCB Postdoctoral Research Travel Award.

Congratulations to Yu-Ju for being selected as a recipient of the ASCB Postdoctoral Research Travel Award! She is going to the ASCB meeting in San Francisco to present her work in December!

 

July 2016: Carlo receives the Great Lakes National Scholarship.

Congratulations to Carlo for receiving the Great Lakes National Scholarship for graduate students pursuing STEM-related degrees!

 

June 2016: Wan-Ru joins the Liou lab.

Wan-Ru Lee is joining the Liou lab as a research scientist and lab manager. Welcome Wan-Ru!

 

February 2016: Chi-Lun has a new position.

Chi-Lun is joining the Lippincott-Schwartz Lab at the HHMI Janelia Research Campus as a Postdoctoral Associate. Good luck in your new lab!

 

January 2016: Carlo joins the Liou lab.

Carlo is joining the Liou lab as a graduate student in the Cell and Molecular Biology Program. Welcome Carlo!

 

June 2015: Jen receives an NIH RO1 Award.

Jen is awarded a five-year NIH RO1 Grant on her application entitled “Functions and Regulation of Endoplasmic Reticulum-Plasma Membrane Junctions”.

 

April 2015: Jen receives a Welch Foundation Award.

Jen is awarded a three-year Welch Foundation Grant on her application entitled “Novel Imaging Probes for Investigating ER Membrane Contact Sites”.

 

April 2015: Chi-Lun’s paper is published in Journal of Biological Chemistry.

 

PIP2 Homeostasis Regulated by Nir2 and Nir3 Proteins at ER–PM junctions

 

Phosphatidylinositol (PI) 4,5-bisphosphate (PIP2) at the plasma membrane (PM) constitutively controls many cellular functions, and its hydrolysis via receptor stimulation governs cell signaling. The PI transfer protein Nir2 is essential for replenishing PM PIP2 following receptor-induced hydrolysis, but key mechanistic aspects of this process remain elusive. Here, we demonstrate that PI at the membrane of the endoplasmic reticulum (ER) is required for the rapid replenishment of PM PIP2 mediated by Nir2. Nir2 detects PIP2 hydrolysis and translocates to ER-PM junctions via binding to phosphatidic acid. With distinct phosphatidic acid binding abilities and PI transfer protein activities, Nir2 and its homolog Nir3 differentially regulate PIP2 homeostasis in cells during intense receptor stimulation and in the resting state, respectively. Our study reveals that Nir2 and Nir3 work in tandem to achieve different levels of feedback based on the consumption of PM PIP2 and function at ER-PM junctions to mediate nonvesicular lipid transport between the ER and the PM.

 

December 2014: Chi-Lun gives a talk at the ASCB meeting.

Congratulations to Chi-Lun for being selected to give a talk on “Differential regulation of phosphatidylinositol 4,5-bisphosphate homeostasis by Nir2 and Nir3 at ER-Plasma membrane junctions”, in the Minisymposium entitled “Small GTPases and Lipids in Membrane Dynamics” under the topic Membrane Traffic: Dynamics and Regulation at the 2014 American Society for Cell Biology (ASCB) Annual meeting in Philadelphia, PA!

 

May 2014: Chi-Lun receives his Ph.D.

Congratulations to Chi-Lun for obtaining his Ph.D. in Integrative Biology (Mechanisms of Disease Track)!

 

November 2013: Chi-Lun’s paper is published in Cell Reports

 

Feedback Regulation of Receptor-Induced Ca2+ Signaling Mediated by E-Syt1 and Nir2 at ER-PM Junctions

 

Endoplasmic reticulum (ER)-plasma membrane (PM) junctions are highly conserved subcellular structures. Despite their importance in Ca2+ signaling and lipid trafficking, the molecular mechanisms underlying the regulation and functions of ER-PM junctions remain unclear. By developing a genetically encoded marker that selectively monitors ER-PM junctions, we found that the connection between ER and PM was dynamically regulated by Ca2+ signaling. Elevation of cytosolic Ca2+ triggered translocation of E-Syt1 to ER-PM junctions to enhance ER-to-PM connection. This subsequently facilitated the recruitment of Nir2, a phosphatidylinositol transfer protein (PITP), to ER-PM junctions following receptor stimulation. Nir2 promoted the replenishment of PM phosphatidylinositol 4,5-bisphosphate (PIP2) after receptor-induced hydrolysis via its PITP activity. Disruption of the enhanced ER-to-PM connection resulted in reduced PM PIP2 replenishment and defective Ca2+ signaling. Altogether, our results suggest a feedback mechanism that replenishes PM PIP2 during receptor-induced Ca2+ signaling via the Ca2+ effector E-Syt1 and the PITP Nir2 at ER-PM junctions.

 

March 2013: Ting-Sung joins the Liou lab.

Ting-Sung is joining the Liou lab as a graduate student in the Molecular Biophysics Program. Welcome Ting-Sung!

 

February 2013: Yu-Ju joins the Liou lab.

Yu-Ju is joining the Liou lab as a postdoctoral fellow supported by a two-year Postdoctoral Fellowship from Taiwan National Science Council. Welcome Yu-Ju!