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Hernandez CC, Gimenez LE, Dahir NS, Peisley A, Cone RD. The unique structural characteristics of the Kir 7.1 inward rectifier potassium channel: a novel player in energy homeostasis control. Am J Physiol Cell Physiol 2023; 324:C694-C706. [PMID: 36717105 PMCID: PMC10026989 DOI: 10.1152/ajpcell.00335.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 02/01/2023]
Abstract
The inward rectifier potassium channel Kir7.1, encoded by the KCNJ13 gene, is a tetramer composed of two-transmembrane domain-spanning monomers, closer in homology to Kir channels associated with potassium transport such as Kir1.1, 1.2, and 1.3. Compared with other channels, Kir7.1 exhibits small unitary conductance and low dependence on external potassium. Kir7.1 channels also show a phosphatidylinositol 4,5-bisphosphate (PIP2) dependence for opening. Accordingly, retinopathy-associated Kir7.1 mutations mapped at the binding site for PIP2 resulted in channel gating defects leading to channelopathies such as snowflake vitreoretinal degeneration and Leber congenital amaurosis in blind patients. Lately, this channel's role in energy homeostasis was reported due to the direct interaction with the melanocortin type 4 receptor (MC4R) in the hypothalamus. As this channel seems to play a multipronged role in potassium homeostasis and neuronal excitability, we will discuss what is predicted from a structural viewpoint and its possible implications for hunger control.
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Affiliation(s)
- Ciria C Hernandez
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States
| | - Luis E Gimenez
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States
| | - Naima S Dahir
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States
| | - Alys Peisley
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States
| | - Roger D Cone
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States
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Wan W, Li Z, Wang X, Tian F, Yang J. Surface-Fabrication of Fluorescent Hydroxyapatite for Cancer Cell Imaging and Bio-Printing Applications. BIOSENSORS 2022; 12:bios12060419. [PMID: 35735566 PMCID: PMC9221440 DOI: 10.3390/bios12060419] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/30/2022] [Accepted: 06/13/2022] [Indexed: 05/07/2023]
Abstract
Hydroxyapatite (HAP) materials are widely applied as biomedical materials due to their stable performance, low cost, good biocompatibility and biodegradability. Here, a green, fast and efficient strategy was designed to construct a fluorescent nanosystem for cell imaging and drug delivery based on polyethyleneimine (PEI) and functionalized HAP via simple physical adsorption. First, HAP nanorods were functionalized with riboflavin sodium phosphate (HE) to provide them with fluorescence properties based on ligand-exchange process. Next, PEI was attached on the surface of HE-functionalized HAP (HAP-HE@PEI) via electrostatic attraction. The fluorescent HAP-HE@PEI nanosystem could be rapidly taken up by NIH-3T3 fibroblast cells and successfully applied to for cell imaging. Additionally, doxorubicin hydrochloride (DOX) containing HAP-HE@PEI with high loading capacity was prepared, and in-vitro release results show that the maximum release of DOX at pH 5.4 (31.83%) was significantly higher than that at pH 7.2 (9.90%), which can be used as a drug delivery tool for cancer therapy. Finally, HAP-HE@PEI as the 3D inkjet printing ink were printed with GelMA hydrogel, showing a great biocompatible property for 3D cell culture of RAW 264.7 macrophage cells. Altogether, because of the enhanced affinity with the cell membrane of HAP-HE@PEI, this green, fast and efficient strategy may provide a prospective candidate for bio-imaging, drug delivery and bio-printing.
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Affiliation(s)
- Weimin Wan
- State Key Laboratory of Component-Based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China; (W.W.); (Z.L.); (X.W.); (F.T.)
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Ziqi Li
- State Key Laboratory of Component-Based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China; (W.W.); (Z.L.); (X.W.); (F.T.)
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
- Tianjin Key Laboratory of Phytochemistry and Pharmaceutical Analysis, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Xi Wang
- State Key Laboratory of Component-Based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China; (W.W.); (Z.L.); (X.W.); (F.T.)
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Fei Tian
- State Key Laboratory of Component-Based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China; (W.W.); (Z.L.); (X.W.); (F.T.)
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
- Tianjin Key Laboratory of Phytochemistry and Pharmaceutical Analysis, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
| | - Jian Yang
- State Key Laboratory of Component-Based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China; (W.W.); (Z.L.); (X.W.); (F.T.)
- Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China
- Correspondence:
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Ionic conduction through single-pore and multipore polymer membranes in aprotic organic electrolytes. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2021.119505] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Queralt-Martín M, Perini DA, Alcaraz A. Specific adsorption of trivalent cations in biological nanopores determines conductance dynamics and reverses ionic selectivity. Phys Chem Chem Phys 2021; 23:1352-1362. [PMID: 33367433 DOI: 10.1039/d0cp04486e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Adsorption processes are central to ionic transport in industrial and biological membrane systems. Multivalent cations modulate the conductive properties of nanofluidic devices through interactions with charged surfaces that depend principally on the ion charge number. Considering that ion channels are specialized valves that demand a sharp specificity in ion discrimination, we investigate the adsorption dynamics of trace amounts of different salts of trivalent cations in biological nanopores. We consider here OmpF from Escherichia coli, an archetypical protein nanopore, to probe the specificity of biological nanopores to multivalent cations. We systematically compare the effect of three trivalent electrolytes on OmpF current-voltage relationships and characterize the degree of rectification induced by each ion. We also analyze the open channel current noise to determine the existence of equilibrium/non-equilibrium mechanisms of ion adsorption and evaluate the extent of charge inversion through selectivity measurements. We show that the interaction of trivalent electrolytes with biological nanopores occurs via ion-specific adsorption yielding differential modulation of ion conduction and selectivity inversion. We also demonstrate the existence of non-equilibrium fluctuations likely related to ion-dependent trapping-detrapping processes. Our study provides fundamental information relevant to different biological and electrochemical systems where transport phenomena involve ion adsorption in charged surfaces under nanoscale confinement.
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Affiliation(s)
- María Queralt-Martín
- Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain.
| | - D Aurora Perini
- Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain.
| | - Antonio Alcaraz
- Laboratory of Molecular Biophysics, Department of Physics, Universitat Jaume I, 12071 Castellón, Spain.
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