Disease relevance of Clcn3

• RESULTS: Together with developmental retardation and higher mortality, the Clcn3-/- mice showed neurological manifestations such as blindness, motor coordination deficit, and spontaneous hyperlocomotion [1].
• Other characteristics of the Clcn3(-/-) mice included an abnormal gait, kyphosis, and absence of hindlimb escape extension upon tail elevation [2].
• Clcn3(-/-) mice had normal serum electrolytes and pH, and exhibited neither hyperglycemia nor rebound hypoglycemia following a glucose load [2].
• Mice lacking the anion channel ClC-3 (Clcn3((-/-))) died from presumed sepsis following intravascular catheter placement, whereas Clcn3((+/+)) littermates survived [3].

High impact information on Clcn3

• Because ClC-3 is a channel protein belonging to a large gene family of chloride channels, these results indicate that ClC-3 encodes ICl.vol in many native mammalian cells [4].
• A mutation of asparagine to lysine at position 579 at the end of the transmembrane domains of ClC-3 abolishes the outward rectification and changes the anion selectivity from I- > Cl- to Cl- > I- but leaves swelling activation intact [4].
• Here we report that functional expression in NIH/3T3 cells of a cardiac clone of another member of the ClC family, ClC-3, results in a large basally active chloride conductance, which is strongly modulated by cell volume and exhibits many properties identical to those of ICl.vol in native cells [4].
• While swelling-activated currents are unchanged in mice with disrupted ClC-3, acidification of synaptic vesicles is impaired and there is severe postnatal degeneration of the retina and the hippocampus [5].
• Disruption of ClC-3, a chloride channel expressed on synaptic vesicles, leads to a loss of the hippocampus [5].

Biological context of Clcn3

• Secretion and cell volume regulation by salivary acinar cells from mice lacking expression of the Clcn3 Cl- channel gene [6].
• CONCLUSIONS: These results indicated that the neurodegeneration observed in the Clcn3-/- mice was caused by an abnormality in the machinery which degrades the cellular protein and was associated with the phenotype of neuronal ceroid lipofuscinosis (NCL) [1].
• 9. Our results provide direct evidence for involvement of ClC-3 in endosomal acidification by Cl- shunting of the interior-positive membrane potential created by the vacuolar H+ pump [7].
• These effects were prevented by a protein kinase A (PKA) inhibitor, KT5720, or by mutation of a single consensus protein kinase C (PKC) phosphorylation site (S51A) on the N-terminus of ClC-3, which also mediates PKC inhibition of ICl,ClC-3 [8].
• Consistent with a normal regulatory volume decrease response, the magnitude and the kinetics of the swell-activated Cl(-) currents in cells from ClC-3-deficient mice were equivalent to those from wild-type mice [6].

Anatomical context of Clcn3

• Within the brain, Clcn3 expression is particularly evident in the hippocampus, olfactory cortex, and olfactory bulb [9].
• In histological analysis, the Clcn3-/- mice showed a pattern of progressive degeneration of the retina, hippocampus and ileal mucosa, which resembled the phenotype observed in cathepsin D knockout mice [1].
• We independently created a mouse lacking the Clcn3 gene which demonstrated similar central nervous system abnormalities, including early postnatal degeneration of retinal photoreceptors [2].
• Indeed, the disruption of ClC-5 impaired the acidification of endosomes, and the knock-out (KO) of ClC-3 that of endosomes and synaptic vesicles [10].
• ClC-3 is thought to mediate swelling-activated plasma membrane currents, but we now show that this broadly expressed chloride channel is present in endosomal compartments and synaptic vesicles of neurons [5].

Associations of Clcn3 with chemical compounds

• Niflumic acid-treated PMNs also had impaired transendothelial migration in vitro, whereas migration in vivo was not altered in Clcn3((-/-)) PMNs [3].
• Cardiomyocytes derived from ClC-3-deficient mice similarly underwent apoptosis after exposure to staurosporine; moreover, apoptosis was prevented by application of DIDS or NPPB [11].

Other interactions of Clcn3

• Moreover, the I(ATPCl) magnitude from wild-type animals was comparable to that from mice with null mutations in the Cftr, Clcn3 and Clcn2 Cl- channel genes [12].
• To clarify whether Cl-/HCO3- exchangers or Cl- channels are targets of DIDS and whether ClC-3 is involved in the apoptotic process, staurosporine-induced reduction of cell viability, DNA laddering and caspase-3 activation were examined in cultured mouse ventricular myocytes derived from wild-type and ClC-3-deficient mice [11].

Analytical, diagnostic and therapeutic context of Clcn3

• Indeed, the ClC-3 gene was expressed in colonic myocytes, as demonstrated by reverse transcriptase polymerase chain reaction performed on isolated cells [13].

References