Annexin A2-S100A10 Represents the Regulatory Component of Maxi-Cl Channel Dependent on Protein Tyrosine Dephosphorylation and Intracellular Ca²⁺.

Background/aims: Maxi-anion channel (Maxi-Cl) is ubiquitously expressed and involved in a number of important cell functions especially by serving as an ATP release pathway. We recently identified SLCO2A1 as its essential core component. However, the regulatory component required for the channel activation/inactivation remains unidentified.

Cell Volume-Activated and Volume-Correlated Anion Channels in Mammalian Cells: Their Biophysical, Molecular, and Pharmacological Properties.

There are a number of mammalian anion channel types associated with cell volume changes. These channel types are classified into two groups: volume-activated anion channels (VAACs) and volume-correlated anion channels (VCACs). VAACs can be directly activated by cell swelling and include the volume-sensitive outwardly rectifying anion channel (VSOR), which is also called the volume-regulated anion channel; the maxi-anion channel (MAC or Maxi-Cl); and the voltage-gated anion channel, chloride channel (ClC)-2.

Involvements of the ABC protein ABCF2 and α-actinin-4 in regulation of cell volume and anion channels in human epithelial cells.

After osmotic swelling, cell volume is regulated by a process called regulatory volume decrease (RVD). Although actin cytoskeletons are known to play a regulatory role in RVD, it is not clear how actin-binding proteins are involved in the RVD process. In the present study, an involvement of an actin-binding protein, α-actinin-4 (ACTN4), in RVD was examined in human epithelial HEK293T cells.

Activation of maxi-anion channel by protein tyrosine dephosphorylation.

The maxi-anion channel with a large single-channel conductance of >300 pS, and unknown molecular identity, is functionally expressed in a large variety of cell types. The channel is activated by a number of experimental maneuvers such as exposing cells to hypotonic or ischemic stress. The most effective and consistent method of activating it is patch membrane excision.

Expression of novel isoforms of the CIC-1 chloride channel in astrocytic glial cells in vitro.

Chloride channels play an important role in glial astrocyte function. However, in astrocytes, no chloride channels besides the gamma-aminobutyric acid (GABA)A receptor, glycine receptor, and ClC-2 chloride channels have been molecularly identified. In this study, we examined the expression of the ClC-1 chloride channel in rat astrocytic glioma C6 cells and rat primary astrocytes.

Ischemia-induced enhancement of CFTR expression on the plasma membrane in neonatal rat ventricular myocytes.

Pathophysiological functions of cardiac cystic fibrosis transmembrane conductance regulator (cCFTR) in ischemia are not well known. Using neonatal rat ventricular cardiomyocytes in primary culture in this study, we thus examined whether the CFTR protein is expressed and is functioning as a cAMP-activated anion channel on the plasma membrane under ischemic conditions. After the cells were subjected to simulated ischemia (O(2) and glucose deprivation), an up-regulation of the CFTR expression was transiently observed in the membrane fraction by Western blot.

DIP (mDia interacting protein) is a key molecule regulating Rho and Rac in a Src-dependent manner.

Cell movement is driven by the coordinated regulation of cytoskeletal reorganization through Rho GTPases downstream of integrin and growth-factor receptor signaling. We have reported that mDia, a target protein of Rho, interacts with Src and DIP. Here we show that DIP binds to p190RhoGAP and Vav2, and that DIP is phosphorylated by Src and mediates the phosphorylation of p190RhoGAP and Vav2 upon EGF stimulation.

Down-regulation of volume-sensitive Cl- channels by CFTR is mediated by the second nucleotide-binding domain.

Transient expression of wild-type human cystic fibrosis transmembrane conductance regulator (CFTR) in HEK293T cells resulted in a profound decrease in the amplitude of volume-sensitive outwardly rectifying Cl- channel (VSOR) current without changing the single-channel amplitude. This effect was not mimicked by expression of the DeltaF508 mutant of CFTR, which did not reach the plasma membrane. The VSOR regulation by CFTR was not affected by G551D mutation at first nucleotide-binding domain (NBD1), which is known to impair CFTR interaction with the outwardly rectifying chloride channel, ORCC, epithelial amiloride-sensitive Na-channel, ENaC, and renal potassium channel, ROMK2.