The PDZ-Lim protein CLP36 in the chicken retina: putative role in neuroplastic changes

RIOS, H.; PAGANELLI, ALEJANDRA R.; FOSSER, N.S.; RONCO, L.

Conferencia; Neuroscience 2013. Meeting of the Society for Neuroscience; 2013

CLP36 belongs to the ALP subfamily of PDZ-LIM proteins, which has 4 functional domains: a PDZ domain at the N-terminal, 1-3 LIM domains at the C-terminal which interacts to the actin cytoskeleton; a ZASP-like domain that interacts with α-actinin (an actin-crosslinking protein) and the ALP-like domain that interacts with protein kinases.  Recently, it was described the association of this protein with the plasma membrane Ca2+-ATPase (PMCA) which plays an essential role in maintaining low cytosolic Ca2+. However, there is little information about the role of CLP36 in central nervous system and retina. The present study describes the localization of CLP36 in the chick retina and the sub-membrane localization at nerve endings by subcellular fractionation, confocal microscopy and western blot during postnatal development and its role in neuronal plasticity. We used Bovans White chickens, reared in 2 experimental conditions: dim light (0.2 lux) and control reared (200 lux).  Both experimental conditions had a diary cycle of 12hs. of cool white light and 12 hs. of darkness.  We also tested how short wavelength light (red light) modifies retinal neuronal circuits during the experimental period.  This third group of animals, red light reared, provides information about spectral deprivation and neuronal plasticity at the external plexiform layer.  New hatched, P6, P9 and P12 chickens were used in this study.  Immunohistochemistry of CLP36 showed a row of terminals at the external plexiform layer (EPL) and terminals at the inner plexiform layer.  Besides, CLP36 was co-expressed with actin, at the double cone synaptic ending.  Interestingly, not all nerve endings at the EPL expressed the protein CLP36, which is only observed ?in the EPL- in synaptic endings of double cones.   Subcellular fractionation showed that CLP36 is present at the 0.9M fraction (synaptosomes), which allow us to confirm our morphological data and data from other authors by which CLP36 could serve as a scaffold of molecular complex, and could be involved in the synaptic structure.  Our observations in chick retina rise new questions about the regulatory pathways of CLP36 protein, its relationships within the double cones endings and its potential role in synaptic plasticity in chicken retina.  Grants from CONICET [PIP00404] and UBACyT.