Project Grant F31NS147663

NASCENT CSF PARTICIPATES IN CRITICAL AUTOCRINE SIGNALING TO MAINTAIN NEUROEPITHELIAL PROGENITORS - PROJECT SUMMARY/ABSTRACT THE VERTEBRATE BRAIN FORMS FROM THE NEURAL TUBE WHICH IS COMPOSED OF STEM CELLS THAT DIVIDE ASYMMETRICALLY TO GENERATE NEURONS AND MAINTAIN THEMSELVES. THESE STEM CELLS, KNOWN AS THE NEUROEPITHELIUM, DIFFERENTIATE FROM THE NEUROECTODERM DURING THE PROCESS OF NEURAL TUBE CLOSURE (NTC). THE NEUROECTODERM CONTACTS AMNIOTIC FLUID (AF), BUT UPON NTC, THE APICAL SIDE OF THE NEUROEPITHELIUM CONTACTS THE NEWLY FORMED (NASCENT) CEREBROSPINAL FLUID (CSF), WHICH ORIGINATES FROM ENCAPSULATED AF. THIS NASCENT CSF CONTACTS THE NEUROEPITHELIUM DURING A CRITICAL DEVELOPMENTAL STAGE, WHERE THE STEM CELLS DIVIDE SYMMETRICALLY TO EXPAND IN NUMBER. LATER IN DEVELOPMENT, WHEN NEURONS ARE FORMING, CSF SIGNALS ENSURE THAT STEM CELLS DIVIDE ASYMMETRICALLY TO MAINTAIN THEMSELVES, RATHER THAN PREMATURELY DIFFERENTIATING INTO NEURONS. HOWEVER, WE KNOW VERY LITTLE ABOUT HOW OR EVEN IF NASCENT CSF SUPPORTS THE EXPANSION OF THE NEUROEPITHELIUM. UNDERSTANDING HOW THE NEUROEPITHELIUM AND NASCENT CSF COMMUNICATE IS CRITICAL TO ADVANCE OUR BASIC KNOWLEDGE OF BRAIN DEVELOPMENT. MOUSE MODELS PROVIDE AN EXCELLENT VERTEBRATE SYSTEM TO STUDY NASCENT CSF BECAUSE MOUSE NTC CLOSELY RESEMBLES HUMAN NTC, AND THERE IS AN ABUNDANCE OF BOTH PRIOR WORK AND TOOLS / RESOURCES AVAILABLE FOR MICE. SINCE NTC OCCURS VERY EARLY IN DEVELOPMENT, THE AMOUNT OF NASCENT CSF PRESENT IS VERY LOW (~2-4UL). THEREFORE, TO STUDY NASCENT CSF AND ITS ROLE IN COMMUNICATING WITH THE NEUROEPITHELIUM, INNOVATIVE AND MODERN APPROACHES ARE NEEDED TO: 1. UNDERSTAND WHAT CELLS ARE SECRETING SIGNALS INTO THE NASCENT CSF AND WHERE NASCENT CSF SIGNALS ARE RECEIVED; 2. CATALOGUE WHAT IS IN THE NASCENT CSF AND WHEN IT IS PRESENT; 3. FIND OUT HOW AND WHICH SIGNALS IN THE CSF PROMOTE THE NEUROEPITHELIUM TO PROLIFERATIVE EXPANSIVELY. TO STUDY THE CROSSTALK BETWEEN NASCENT CSF AND THE NEUROEPITHELIUM, I WILL USE 3 MAIN APPROACHES. FIRST, I WILL USE OPENST, A NOVEL HIGH-RESOLUTION SPATIAL TRANSCRIPTOMICS PLATFORM TO GENERATE THE SPATIALLY-RESOLVED GENE EXPRESSION PROFILE OF THE ENTIRE NEUROEPITHELIUM. THIS WILL ENABLE ME TO KNOW WHAT SIGNALS THE NEUROEPITHELIUM IS PRODUCING, AND WHERE RECEPTORS ARE LOCATED IN THE NEUROEPITHELIUM. SECOND, I WILL USE TURBOID TO LABEL THE PROTEINS ARE SECRETED INTO THE NASCENT CSF, WHICH WILL ALLOW ME TO KNOW WHAT SIGNALS ARE IN THE CSF, AND DISTINGUISH THOSE THAT ORIGINATE FROM THE NEUROEPITHELIUM VS. THOSE THAT ARISE FROM ENCAPSULATED AF. FINALLY, I WILL USE WHOLE EMBRYO EX UTERO CULTURE TO ACTIVATE OR INHIBIT SPECIFIC SIGNALING PATHWAYS IN THE NASCENT CSF AND OBSERVE THEIR EFFECT ON THE NEUROEPITHELIUM. THIS WILL INFORM WHICH SIGNALS MAINTAIN NEUROEPITHELIAL EXPANSION AND WHETHER THEY ACT THROUGH THE NASCENT CSF.