Deficiency of Anoctamin 5/TMEM16E causes nuclear positioning defect and impairs Ca2+ signaling of differentiated C2C12 myotubes

Tam Thi Thanh Phuong,Jieun An,Sun Hwa Park,Ami Kim,Hyun Bin Choi,Tong Mook Kang 대한약리학회 2019 The Korean Journal of Physiology & Pharmacology Vol.23 No.6

Anoctamin 5 (ANO5)/TMEM16E belongs to a member of the ANO/ TMEM16 family member of anion channels. However, it is a matter of debate whether ANO5 functions as a genuine plasma membrane chloride channel. It has been recognized that mutations in the ANO5 gene cause many skeletal muscle diseases such as limb girdle muscular dystrophy type 2L (LGMD2L) and Miyoshi muscular dystrophy type 3 (MMD3) in human. However, the molecular mechanisms of the skeletal myopathies caused by ANO5 defects are poorly understood. To understand the role of ANO5 in skeletal muscle development and function, we silenced the ANO5 gene in C2C12 myoblasts and evaluated whether it impairs myogenesis and myotube function. ANO5 knockdown (ANO5-KD) by shRNA resulted in clustered or aggregated nuclei at the body of myotubes without affecting differentiation or myotube formation. Nuclear positioning defect of ANO5-KD myotubes was accompanied with reduced expression of Kif5b protein, a kinesin-related motor protein that controls nuclear transport during myogenesis. ANO5-KD impaired depolarization-induced [Ca2+]i transient and reduced sarcoplasmic reticulum (SR) Ca2+ storage. ANO5-KD resulted in reduced protein expression of the dihydropyridine receptor (DHPR) and SR Ca2+-ATPase subtype 1. In addition, ANO5-KD compromised co-localization between DHPR and ryanodine receptor subtype 1. It is concluded that ANO5-KD causes nuclear positioning defect by reduction of Kif5b expression, and compromises Ca2+ signaling by downregulating the expression of DHPR and SERCA proteins.

Deficiency of Anoctamin 5/TMEM16E causes nuclear positioning defect and impairs Ca²⁺ signaling of differentiated C2C12 myotubes

Phuong, Tam Thi Thanh,An, Jieun,Park, Sun Hwa,Kim, Ami,Choi, Hyun Bin,Kang, Tong Mook The Korean Society of Pharmacology 2019 The Korean Journal of Physiology & Pharmacology Vol.23 No.6

Anoctamin 5 (ANO5)/TMEM16E belongs to a member of the ANO/TMEM16 family member of anion channels. However, it is a matter of debate whether ANO5 functions as a genuine plasma membrane chloride channel. It has been recognized that mutations in the ANO5 gene cause many skeletal muscle diseases such as limb girdle muscular dystrophy type 2L (LGMD2L) and Miyoshi muscular dystrophy type 3 (MMD3) in human. However, the molecular mechanisms of the skeletal myopathies caused by ANO5 defects are poorly understood. To understand the role of ANO5 in skeletal muscle development and function, we silenced the ANO5 gene in C2C12 myoblasts and evaluated whether it impairs myogenesis and myotube function. ANO5 knockdown (ANO5-KD) by shRNA resulted in clustered or aggregated nuclei at the body of myotubes without affecting differentiation or myotube formation. Nuclear positioning defect of ANO5-KD myotubes was accompanied with reduced expression of Kif5b protein, a kinesin-related motor protein that controls nuclear transport during myogenesis. ANO5-KD impaired depolarization-induced $[Ca2^{+}]_i$ transient and reduced sarcoplasmic reticulum (SR) $Ca^{2+}$ storage. ANO5-KD resulted in reduced protein expression of the dihydropyridine receptor (DHPR) and SR $Ca^{2+}-ATPase$ subtype 1. In addition, ANO5-KD compromised co-localization between DHPR and ryanodine receptor subtype 1. It is concluded that ANO5-KD causes nuclear positioning defect by reduction of Kif5b expression, and compromises $Ca^{2+}$ signaling by downregulating the expression of DHPR and SERCA proteins.

Stromal interaction molecule 2 regulates C2C12 myoblast differentiation

Tam Thi Thanh Phuong,강동묵 한국한의학연구원 2015 Integrative Medicine Research Vol.4 No.4

Background Enhanced intracellular Ca2+ signaling by stromal interaction molecule 1 (STIM1)-mediated store-operated Ca2+ entry (SOCE) is required for skeletal muscle differentiation. However, the contribution of STIM2, STIM1's analogue protein, on muscle cell differentiation has not been clearly elucidated. The present study aimed to explore the contribution of STIM2-mediated SOCE on C2C12 myoblast differentiation. Methods Changes in STIM2 expression level (reverse transcription-polymerase chain reaction and Western blotting) and SOCE activity ([Ca2+]i measurement) were measured during 3 days of in vitro differentiation of C2C12 skeletal myoblast. Transcriptional regulation of STIM2 by nuclear factor of activated T cells, cytoplasmic (NFATc) overexpression was observed, and the effect of STIM2 knockdown on NFAT transcriptional activity (luciferase assay) and myoblast differentiation was quantified. Results Increase of STIM2 protein level and enhanced SOCE activity were observed in differentiating myoblasts. Treatment with a SOCE blocker (2-APB) inhibited the differentiation. Overexpression of NFATc1 increased STIM2 expression and SOCE activity. Knockdown of STIM2 decreased NFAT transcriptional activity, SOCE activity, and differentiation of C2C12 myoblast. Conclusion It is suggested that STIM2-activated SOCE controls C2C12 myoblast differentiation.

Detection of Vibrio cholerae O1 by Using Cerium Oxide Nanowires - Based Immunosensor with Different Antibody Immobilization Methods

Phuong Dinh Tam,Nguyen Luong Hoang,Hoang Lan,Pham Hung Vuong,Ta Thi Nhat Anh,Tran Quang Huy,Nguyen Thanh Thuy 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.10

In this work, we evaluated the effects of different antibody immobilization strategies on the response of a CeO2-nanowires (NWs)-based immunosensor for V ibrio cholerae O1 detection. Accordingly, the changes in the electron-transfer resistance (Ret) from before to after cells bind to an antibody-modified electrode prepared by using three different methods of antibody immobilization were determined. The values were 16.2%, 8.3%, and 6.65% for the method that utilized protein A, antibodies activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)/Nhydroxysuccinimide (NHS), and absorption, respectively. Cyclic voltammetry confirmed that the change in the current was highest for the immunosensors prepared using protein A (11%), followed by those prepared with EDC/NHS-activated antibodies (9%), and finally, those prepared through absorption (7.5%). The order of the antibody immobilization strategies in terms of resulting immunosensor detection limit and sensitivity was as follows order: absorption (3.2 × 103 CFU/mL; 45.1 /CFU·mL−1) < EDC/NHS-activated antibody (1.0 × 103 CFU/mL; 50.6 /CFU·mL−1) < protein A (1.0 × 102 CFU/mL; 65.8 /CFU·mL−1). Thus, we confirmed that the protein A - mediated method showed significantly high cell binding efficiencies compared to the random immobilization method.

Determinants of Operational Self-Sustainability of Microfinance Institutions in Vietnam

LE, Thanh Tam,DAO, Lan Phuong,DO, Ngoc Mai,TRUONG, Thi Hoai Linh,NGUYEN, Thi Thuy Duong,TRAN, Chung Thuy Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.10

The purpose of this paper is to investigate the determinants of the Operational Self-Sustainability (OSS) of Vietnamese microfinance institutions (MFIs). This research uses both qualitative and quantitative research methods: (i) qualitative research was via in-depth interviews with ten microfinance practitioners, policymakers and researchers; (ii) quantitative research was conducted by using panel data of 34 MFIs in the period 2011-2015 with binary logistics and OLS regressions. Results are as follows: (i) MFIs' OSS in Vietnam are mainly determined by five key factors: portfolio at risk (PAR>30), capital structure, gross loan portfolio, scope of activities and legal form; (ii) OSS are most affected by legal status (social organizations have better OSS than formal MFIs or programs/projects), location (MFIs focus in one province have higher OSS than working nationwide or just in one district), capital structure (MFIs with more equity proportion have higher OSS); (iii) surprisingly, average loan size per borrower and age of MFIs do not have statistically significant correlation with OSS. The key recommendations are: (i) MFIs should focus on its professionality and increase its equity; (ii) related stakeholders such as State Bank of Vietnam should promote the enabling ecosystem for microfinance development to enhance poverty reduction and economic development.