The overall goal of the Ozdinler Lab is to understand the cellular and molecular basis of selective neuronal vulnerability. The lab primarily focuses on the corticospinal motor neurons (CSMN), the neurons that are important for the initiation and modulation of voluntary movement. CSMN degeneration is a key feature in many motor neuron diseases, such as amyotrophic lateral sclerosis (ALS), hereditary spastic paraplegia (HSP), and primary lateral sclerosis (PLS).
Our lab focuses on the biology of upper motor neurons with respect to neurodegerative diseases. We are a member of the Les Turner ALS Research and Patient Center at Northwestern, and our overall goal is to bring effective treatment strategies to ALS and other related diseases via collaborative and integrated efforts.
Dr. Ozdinler is affiliated with Mesulam Center for Cognitive Neurology and Alzheimer’s Disease and Robert H. Lurie Comprehensive Cancer Center.
Corticospinal motor neurons (CSMN) are special in their ability to receive and integrate cortical input, and to convey this as a message to spinal cord targets. Therefore, they act as the “spokesperson” of the cerebral cortex for the initiation and modulation of voluntary movement. Their degeneration is a key feature of many neurodegenerative diseases, in which voluntary movement is impaired. CSMN vulnerability and progressive degeneration can occur due to intrinsic and extrinsic factors. The intrinsic factors involve the cellular and genetic events that occur primarily in these vulnerable neuron populations, and extrinsic factors refer to the events that occur outside of CSMN that impact their health as well as the timing and extent of their progressive degeneration. Since ALS is one of the most complex diseases, we believe that CSMN degeneration is a result of both intrinsic and extrinsic factors.
Intrinsic factors responsible for CSMN vulnerability
To reveal the cellular and molecular cascade of events that occur in vulnerable and diseased CSMN, we generated the UCHL1-eGFP mice, a reporter mouse model, in which CSMN are genetically labeled with eGFP expression that is stable and long-lasting. CSMN identity of eGFP+ neurons in the motor cortex is confirmed by retrograde labeling, molecular marker expression, and electrophysiological analysis. Being able to visualize and distinguish CSMN among many different types of cortical neurons and cells enable their detailed cellular analysis with high precision and clarity.
By crossbreeding this reporter mouse with disease models of ALS that display CSMN vulnerability, such as the hSOD1G93A, TDP43, and AlsinKO mice, we generated CSMN reporter lines of the disease. This is rather important because CSMN become vulnerable because of different causes in these different models of the disease and we now can isolate pure populations of CSMN that become vulnerable due to mutations in the SOD1 gene, TDP43 pathology and absence of Alsin function.
In an effort to reveal the underlying cellular and molecular basis of selective vulnerability and progressive degeneration, we now FACS-purify healthy and diseased CSMN, which develop disease because of different underlying factors as a pure neuron population at different stages of disease initiation and progression, and investigate the changes in gene expression by RNASeq, microarray and other gene expression profiles. We then perform comparative analysis to reveal the common and unique cellular events that are responsible for diseases that are manifested due to different underlying causes. In line with these investigations, we also began to analyze the protein content of pure populations of both healthy and diseased CSMN using top-down and bottom-up proteomics approaches.
This project is funded by Les Turner ALS Foundation, ALS Association, and NIH.
Extrinsic factors responsible for CSMN vulnerability
Building evidence reveal the importance of non-neuronal cells and innate immunity on motor neuron vulnerability and progressive degeneration. Yet, the molecular basis of their interaction and the mode of disease initiation and progression are not fully understood. By using MCP1-CCR2 double transgenic mice in which cells that are involved in innate immunity are genetically labeled with eGFP (green) and RFP (red) gene. We generated triple transgenic MCP1-CCR2-hSOD1G93A mice, in an effort to reveal the genetic and molecular changes that occur in cells that modulate innate immunity and how that related to motor neuron vulnerability in the motor cortex and spinal cord.
This project is funded by Les Turner ALS Foundation and ALS Association.
Developing effective gene delivery approaches to upper motor neurons
Our ongoing research began to reveal the molecular basis of underlying causes that lead to upper motor neuron vulnerability and progressive degeneration. Since our overall goal is to develop effective and long-term treatment strategies, we will need novel approaches to deliver solutions directly to the diseased upper motor neurons without affecting other cortical neurons and cells. To this end we need to achieve selective gene delivery in the cortex, which is very heterogeneous and complex. We are developing AAV-mediated gene delivery approaches to upper motor neurons in need using novel approaches, tools and reagents.
This project earned NUCATS Translational Innovation award and is funded by the Les Turner ALS Foundation.
Including upper motor neuron survival in preclinical drug screening
To date many drug discovery efforts have failed even though they showed very encouraging results by enhancing lifespan of ALS mouse models. Since motor neurons are almost identical at a cellular level, we propose to shift our attention from mice to vulnerable motor neurons, and study their survival requirements as a prerequisite for clinical trials. We think that improvement of motor neuron health is paramount for developing effective treatment strategies. Since both healthy and diseased CSMN are genetically labeled with eGFP expression that distinguishes them from other cortical neurons and cells, we began to reveal their survival in the presence of select compounds that has the potential to move forward in clinical trials. This project is very important for improving success rates of future clinical trials and has the potential to reveal new drugs for ALS and other motor neuron diseases.