Secretagogin-dependent matrix metalloprotease-2 release from neurons regulates neuroblast migration

Abstract

The rostral migratory stream (RMS) is viewed as a glia-enriched conduit of forward-migrating neuroblasts in which chemorepulsive signals control the pace of forward migration. Here we demonstrate the existence of a scaffold of neurons that receive synaptic inputs within the rat, mouse, and human fetal RMS equivalents. These neurons express secretagogin, a Ca 2+ -sensor protein, to execute an annexin V-dependent externalization of matrix metalloprotease-2 (MMP-2) for reconfiguring the extracellular matrix locally. Mouse genetics combined with pharmacological probing in vivo and in vitro demonstrate that MMP-2 externalization occurs on demand and that its loss slows neuroblast migration. Loss of function is particularly remarkable upon injury to the olfactory bulb. Cumulatively, we identify a signaling cascade that provokes structural remodeling of the RMS through recruitment of MMP-2 by a previously unrecognized neuronal constituent. Given the life-long presence of secretagogin-containing neurons in human, this mechanism might be exploited for therapeutic benefit in rescue strategies.human fetus | calcium-binding protein | cell motility | restorative strategy | olfactory system T he subventricular zone of adult rodents and its human fetal equivalent (1) generate neuroblasts that migrate through the rostral migratory stream (RMS) to supply the olfactory bulb with new neurons (2). Tangential neuroblast migration in the RMS is regulated by various environmental factors including growth factors (3-10), ephrins (11), and cell adhesion-related cues (12)(13)(14). Many of these regulatory events are executed through direct intercellular interactions: Chain-migrating neuroblasts move in contact with each other (15), and neuron-glia communication shapes the journey of newborn cells toward the olfactory bulb (16,17). In particular, astrocytes can vector neuroblast movement by secreting netrin (18) and VGEF (19,20) and regulate the speed of migration by releasing GABA (21, 22) while actively reconfiguring their own network in response to neuroblast-derived signals through the Slit/Robo machinery (16).Brain extracellular matrix is a juxtacellular scaffold that defines the microenvironmental arrangements surrounding each cell. Extracellular matrix components were earlier implicated in neuroblast migration: Tenascin-R can mediate activity-dependent neuroblast recruitment, (23) and hyaluronan and its receptor, Rhamm, driving hyaluronan-mediated motility, are selectively expressed in the adult RMS (24). Notably, members of the matrix metalloproteinase (MMP) family are recognized as critical for restructuring the extracellular matrix by cleaving all its components (25, 26). However, MMP activity and efficacy in neurogenic niches were studied chiefly in the early postnatal nervous system (12), during axonal growth, and upon cancer cell invasion (27-29) with pathologically increased proliferative capacity. In the RMS, MMP inhibitors reduce the rate of neuroblast migration in young mice, but chain migration remains unaffected in the ...

Distribution and classification of the extracellular matrix in the olfactory bulb

“…We then used immunohistochemistry to explore the phenotype of the above extracellular matrix componentimmunoreactive structures. Extracellular matrix components showed a distribution pattern which was similar we found in the murine olfactory bulb (Hanics et al 2017). HAPLN-1 immunoreactivity was concentrated in the external plexiform layer with the glomerular layer being rather spared from immunostaining ( Fig.…”

Multiple Origins of Secretagogin Expressing Cortical GABAergic Neuron Precursors in the Early Human Fetal Telencephalon

“…Although, we found evidence of SCGN being co-expressed with either MMP2 or ANXA5, it was more striking to note the extensive independent expression of these three proteins. Even though MMP2 is proposed to promote neuroblast migration and neurite outgrowth by remodeling the local extracellular matrix (ECM; Lee et al, 2006 ; Mao et al, 2016 ; Hanics et al, 2017 ) it showed strong localization to the CP where cortical neurons stop migrating and where the cells are densely packed with little neurite outgrowth, or ingrowth of afferents, at this stage of development (Bystron et al, 2008 ). Furthermore, the effect of MMP2 on neural progenitors appears to be to maintain proliferation and prevent differentiation (Sinno et al, 2013 ; Shu et al, 2018 ) therefore expression of MMP2 in the CP appears paradoxical.…”

“…It has been shown in the rostral migratory stream (RMS) a pathway guiding neuroblast migration from subventricular zone to olfactory bulb throughout life (Lois and Alvarez-Buylla, 1994 ) there is a scaffold of SCGN expressing neurons that exocytose matrix metalloprotease 2 (MMP2) via activation of SCGN and recruitment of Annexin V (ANXA5). Furthermore, restructuring of the extracellular matrix by MMP2 promotes neuroblast migration (Hanics et al, 2017 ). Recent research has shown that in the early postnatal forebrain, nearby to the RMS, lies a dorsal migratory stream that supplies GABAergic neurons to late-developing prefrontal cortical areas in both humans (up to 5 months postnatally; Sanai et al, 2011 ; Paredes et al, 2016 ) and ferret (up to 90 days postnatally; Ellis et al, 2019 ).…”

A TRPV 1‐to‐secretagogin regulatory axis controls pancreatic β‐cell survival by modulating protein turnover

“…Cells were routinely sub-cultured in 24-well plates up to passage 120, and allowed to reach~80% confluence. Knock-down of secretagogin expression was achieved by the co-application of secretagogin siRNA (50 nM; Santa Cruz) and jetPRIME transfection reagent Generation of secretagogin À/À and b-Scgn CKO mice Secretagogin À/À (Scgn À/À ) mice (Hanics et al, 2017) were customgenerated at MMRRC (University of California, Davis, Mouse Biology Program) using the "two-in-one" targeting strategy (Skarnes et al, 2011), which generates full knock-outs by expressing a termination signal after exon 3 of the secretagogin gene. The ensuing truncated protein terminates before the first EF-hand domain, excluding Ca 2+binding activity.…”

“…Considering the abundance of secretagogin on, for example, ER membranes (Romanov et al, 2015;Hanics et al, 2017), we screened possible protein-protein interactions unrelated to either the cytoskeleton or SNARE assembly. By using His 6 -tagged recombinant secretagogin in the presence of Ca 2+ (100 lM), we precipitated putative interacting partners from INS-1E cells and identified their amino acid sequences by mass spectrometry.…”