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Lee SP, Chao SC, Chou MF, Huang SF, Dai NT, Wu GJ, Tsai CS, Loh SH, Tsai YT. Characterization of intracellular buffering power in human induced pluripotent stem cells and the loss of pluripotency is delayed by acidic stimulation and increase of NHE1 activity. J Cell Physiol 2020; 236:1515-1528. [PMID: 32841374 DOI: 10.1002/jcp.29959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/18/2020] [Accepted: 07/07/2020] [Indexed: 11/07/2022]
Abstract
The homeostasis of intracellular pH (pHi ) affects many cellular functions. Our previous study has established a functional and molecular model of the active pHi regulators in human induced pluripotent stem cells (hiPSCs). The aims of the present study were to further quantify passive pHi buffering power (β) and to investigate the effects of extracellular pH and Na+ -H+ exchanger 1 (NHE1) activity on pluripotency in hiPSCs. pHi was detected by microspectrofluorimetry with pH-sensitive dye-BCECF. Western blot, immunofluorescence staining, and flow cytometry were used to detect protein expression and pluripotency. Our study in hiPSCs showed that (a) the value of total (βtot ), intrinsic (βi ), and CO2 -dependent ( β C O 2 ) buffering power all increased while pHi increased; (b) during the spontaneous differentiation for 4 days, the β values of βtot and β C O 2 changed in a tendency of decrease, despite the absence of statistical significance; (c) an acidic cultured environment retained pluripotency and further upregulated expression and activity of NHE1 during spontaneous differentiation; (d) inhibition on NHE1 activity promoted the loss of pluripotency. In conclusion, we, for the first time, established a quantitative model of passive β during differentiation and demonstrated that maintenance of NHE1 at a higher level was of critical importance for pluripotency retention in hiPSCs.
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Affiliation(s)
- Shiao-Pieng Lee
- Department of Dentistry, School of Dentistry, Division of Oral and Maxillofacial Surgery, Tri-Service General Hospital and National Defense Medical Center, Taipei, Taiwan
| | - Shih-Chi Chao
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Mei-Fang Chou
- Department of Pharmacy Practice, Tri-Service General Hospital, Taipei, Taiwan
| | - Shu-Fu Huang
- Department of Pharmacy Practice, Tri-Service General Hospital, Taipei, Taiwan
| | - Niann-Tzyy Dai
- Department of Surgery, Division of Plastic and Reconstructive Surgery, Tri-Service General Hospital, Taipei, Taiwan
| | - Gwo-Jang Wu
- Department of Obstetrics and Gynecology, Tri-Service General Hospital, Taipei, Taiwan
| | - Chien-Sung Tsai
- Department of Surgery, Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
- Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan
- Institute of Pharmacy, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Shih-Hurng Loh
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
- Department of Pharmacy Practice, Tri-Service General Hospital, Taipei, Taiwan
- Department of Surgery, Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yi-Ting Tsai
- Department of Surgery, Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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Loh SH, Chang CY, Huang SF, Chao SC, Lin WK, Huang EYK, Tsai CS, Tsai YT. Functional effects of urotensin-II on intracellular pH regulators in human radial artery smooth muscle cells. Peptides 2020; 126:170236. [PMID: 31874233 DOI: 10.1016/j.peptides.2019.170236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 12/11/2019] [Accepted: 12/16/2019] [Indexed: 02/04/2023]
Abstract
The regulation of intracellular pH (pHi) plays a vital role in various cellular functions. We previously demonstrated that three different acid extruders, the Na+-H+ exchanger (NHE), Na+-HCO3- co-transporter (NBC) and H+-linked monocarboxylate transporter (MCT), functioned together in cultured human radial artery smooth muscle cells (HRASMCs). However, the functions of acid-loading transporters in HRASMCs remain poorly understood. Urotensin II (U-II), one of the most potent vasoconstrictors, is highly expressed in many cardiovascular diseases. The aim of this present study was to determine the concentration effect of U-II (3 pM∼100 nM) on the functional activity of pHi regulators in HRASMCs. Cultured HRASMCs were derived from segments of human radial arteries obtained from patients undergoing bypass grafting. Changes in pHi recovery due to intracellular acidification and alkalization induced by NH4Cl prepulse and Na-acetate prepulse, respectively, were detected by microspectrofluorimetry with the pH-sensitive fluorescent dye BCECF. Our present study showed that (a) U-II increased the activity of NHE in a concentration-dependent manner but did not change that of NBC or MCT or resting pHi, (b) the Cl--OH- exchanger (CHE) facilitated base extrusion, and (c) U-II induced a concentration-dependent increase in the activity of CHE. In conclusion, for the first time, our results highlight a concentration-dependent increase in the activity of NHE and CHE, but not NBC and MCT, induced by U-II in HRASMCs.
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Affiliation(s)
- Shih-Hurng Loh
- Department of Pharmacology, National Defense Medical Center, Taipei, 11490, Taiwan; Department of Pharmacy Practice, Tri-Service General Hospital, National Defense Medical Center, Taipei, 11490, Taiwan; Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, 11490, Taiwan.
| | - Chung-Yi Chang
- Department of General Surgery, Cheng-Hsieng General Hospital, Taipei, 11200, Taiwan.
| | - Shu-Fu Huang
- Department of Pharmacy Practice, Tri-Service General Hospital, National Defense Medical Center, Taipei, 11490, Taiwan.
| | - Shih-Chi Chao
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, 11490, Taiwan.
| | - Wei-Kuo Lin
- Department of Pharmacology, National Defense Medical Center, Taipei, 11490, Taiwan.
| | - Eagle Yi-Kung Huang
- Department of Pharmacology, National Defense Medical Center, Taipei, 11490, Taiwan.
| | - Chien-Sung Tsai
- Department of Pharmacology, National Defense Medical Center, Taipei, 11490, Taiwan; Division of Cardiovascular Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
| | - Yi-Ting Tsai
- Division of Cardiovascular Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
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Chao SC, Wu GJ, Huang SF, Dai NT, Huang HK, Chou MF, Tsai YT, Lee SP, Loh SH. Functional and molecular mechanism of intracellular pH regulation in human inducible pluripotent stem cells. World J Stem Cells 2018; 10:196-211. [PMID: 30613313 PMCID: PMC6306555 DOI: 10.4252/wjsc.v10.i12.196] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/14/2018] [Accepted: 12/05/2018] [Indexed: 02/06/2023] Open
Abstract
AIM To establish a functional and molecular model of the intracellular pH (pHi) regulatory mechanism in human induced pluripotent stem cells (hiPSCs).
METHODS hiPSCs (HPS0077) were kindly provided by Dr. Dai from the Tri-Service General Hospital (IRB No. B-106-09). Changes in the pHi were detected either by microspectrofluorimetry or by a multimode reader with a pH-sensitive fluorescent probe, BCECF, and the fluorescent ratio was calibrated by the high K+/nigericin method. NH4Cl and Na-acetate prepulse techniques were used to induce rapid intracellular acidosis and alkalization, respectively. The buffering power (β) was calculated from the ΔpHi induced by perfusing different concentrations of (NH4)2SO4. Western blot techniques and immunocytochemistry staining were used to detect the protein expression of pHi regulators and pluripotency markers.
RESULTS In this study, our results indicated that (1) the steady-state pHi value was found to be 7.5 ± 0.01 (n = 20) and 7.68 ± 0.01 (n =20) in HEPES and 5% CO2/HCO3--buffered systems, respectively, which were much greater than that in normal adult cells (7.2); (2) in a CO2/HCO3--buffered system, the values of total intracellular buffering power (β) can be described by the following equation: βtot = 107.79 (pHi)2 - 1522.2 (pHi) + 5396.9 (correlation coefficient R2 = 0.85), in the estimated pHi range of 7.1-8.0; (3) the Na+/H+ exchanger (NHE) and the Na+/HCO3- cotransporter (NBC) were found to be functionally activated for acid extrusion for pHi values less than 7.5 and 7.68, respectively; (4) V-ATPase and some other unknown Na+-independent acid extruder(s) could only be functionally detected for pHi values less than 7.1; (5) the Cl-/ OH- exchanger (CHE) and the Cl-/HCO3- anion exchanger (AE) were found to be responsible for the weakening of intracellular proton loading; (6) besides the CHE and the AE, a Cl--independent acid loading mechanism was functionally identified; and (7) in hiPSCs, a strong positive correlation was observed between the loss of pluripotency and the weakening of the intracellular acid extrusion mechanism, which included a decrease in the steady-state pHi value and diminished the functional activity and protein expression of the NHE and the NBC.
CONCLUSION For the first time, we established a functional and molecular model of a pHi regulatory mechanism and demonstrated its strong positive correlation with hiPSC pluripotency.
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Affiliation(s)
- Shih-Chi Chao
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 11490, Taiwan
| | - Gwo-Jang Wu
- Department of Obstetrics and Gynecology, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
| | - Shu-Fu Huang
- Department of Pharmacy Practice, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
| | - Niann-Tzyy Dai
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
| | - Hsu-Kai Huang
- Division of Chest Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
| | - Mei-Fang Chou
- Department of Pharmacy Practice, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
| | - Yi-Ting Tsai
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei 11490, Taiwan
- Division of Cardiovascular Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
| | - Shiao-Pieng Lee
- Division of Oral and Maxillofacial Surgery, Department of Dentistry, School of Dentistry, Tri-Service General Hospital and National Defense Medical Center, Taipei 11490, Taiwan
| | - Shih-Hurng Loh
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 11490, Taiwan
- Department of Pharmacy Practice, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
- Department of Pharmacology, National Defense Medical Center, Taipei 11490, Taiwan
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