Sanalidou, S. | Search bioRxiv

bioRxiv2023

Cadherins orchestrate specific patterns of perisomatic inhibition onto distinct pyramidal cell populations

In the mammalian neocortex, excitatory pyramidal cells are assembled into distinct subnetworks, which project to different brain areas. GABAergic interneurons were long thought to connect promiscuously and extensively to pyramidal neurons, but recent evidence supports the existence of a cell type-specific inhibitory connectome. How and when interneurons establish such a precise connectivity pattern among intermingled populations of excitatory neurons remains enigmatic. Here, we investigated the molecular rules shaping cell type- and input-specific inhibitory connectivity in different Layer 5 (L5) pyramidal cell populations. We found that neighboring L5 intra- (L5 IT) and extra-telencephalic (L5 ET) neurons receive different combinations of inhibitory perisomatic inputs from Parvalbumin- (PV+) and Cholecystokynine-positive (CCK+) basket cells. We also identified Cdh12 and Cdh13, two cadherin superfamily members, as critical mediators of L5 pyramidal cell type-specific inhibitory connectivity. Our data revealed a minimal overlap between L5 IT and L5 ET presynaptic inhibitory networks, and suggests that different populations PV+ basket cells innervate distinct L5 pyramidal cell types. Altogether, our work unravels the contribution of cadherins in shaping cortical interneuron wiring and provides new insights into the development of inhibitory microcircuits.

neuroscience↗

bioRxiv2021

Cortical wiring by synapse-specific control of local protein synthesis

Neurons use local protein synthesis as a mechanism to support their morphological complexity, which requires independent control across multiple subcellular compartments including individual synapses. However, to what extent local translation is differentially regulated at the level of specific synaptic connections remains largely unknown. Here, we identify a signaling pathway that regulates the local synthesis of proteins required for the formation of excitatory synapses on parvalbumin-expressing (PV+) interneurons in the mouse cerebral cortex. This process involves the regulation of the mTORC1 inhibitor Tsc2 by the receptor tyrosine kinase ErbB4, which enables the local control of mRNA translation in a cell type-specific and synapse-specific manner. Ribosome-associated mRNA profiling reveals a molecular program of synaptic proteins that regulates the formation of excitatory inputs on PV+ interneurons downstream of ErbB4 signaling. Our work demonstrates that local protein translation is regulated at the level of specific connections to control synapse formation in the nervous system.

neuroscience↗