Cells (Aug 2022)

The CaMKII/MLC1 Axis Confers Ca<sup>2+</sup>-Dependence to Volume-Regulated Anion Channels (VRAC) in Astrocytes

  • Maria Stefania Brignone,
  • Angela Lanciotti,
  • Antonio Michelucci,
  • Cinzia Mallozzi,
  • Serena Camerini,
  • Luigi Catacuzzeno,
  • Luigi Sforna,
  • Martino Caramia,
  • Maria Cristina D’Adamo,
  • Marina Ceccarini,
  • Paola Molinari,
  • Pompeo Macioce,
  • Gianfranco Macchia,
  • Tamara Corinna Petrucci,
  • Mauro Pessia,
  • Sergio Visentin,
  • Elena Ambrosini

DOI
https://doi.org/10.3390/cells11172656
Journal volume & issue
Vol. 11, no. 17
p. 2656

Abstract

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Astrocytes, the main glial cells of the central nervous system, play a key role in brain volume control due to their intimate contacts with cerebral blood vessels and the expression of a distinctive equipment of proteins involved in solute/water transport. Among these is MLC1, a protein highly expressed in perivascular astrocytes and whose mutations cause megalencephalic leukoencephalopathy with subcortical cysts (MLC), an incurable leukodystrophy characterized by macrocephaly, chronic brain edema, cysts, myelin vacuolation, and astrocyte swelling. Although, in astrocytes, MLC1 mutations are known to affect the swelling-activated chloride currents (ICl,swell) mediated by the volume-regulated anion channel (VRAC), and the regulatory volume decrease, MLC1′s proper function is still unknown. By combining molecular, biochemical, proteomic, electrophysiological, and imaging techniques, we here show that MLC1 is a Ca2+/Calmodulin-dependent protein kinase II (CaMKII) target protein, whose phosphorylation, occurring in response to intracellular Ca2+ release, potentiates VRAC-mediated ICl,swell. Overall, these findings reveal that MLC1 is a Ca2+-regulated protein, linking volume regulation to Ca2+ signaling in astrocytes. This knowledge provides new insight into the MLC1 protein function and into the mechanisms controlling ion/water exchanges in the brain, which may help identify possible molecular targets for the treatment of MLC and other pathological conditions caused by astrocyte swelling and brain edema.

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