Brain Disease
Epilepsy, brain tumors, Parkinson’s disease, stroke and Alzheimer’s disease are common brain disorders. For these common brain disorders, there is no cure but medical intervention can help to lessen the symptoms. C. elegans are model organisms to study Parkinson’s Disease and Alzheimer’s Disease; their rapid development make them great model organism to study these age-related diseases. Additionally, their ease of genetic manipulation makes C. elegans a great model organism to study specific genes related to any of these diseases. However, because of the major structural differences between human and C. elegans brains, mice are more frequently used to model these disorders.
1. Epilepsy: recurrent, spontaneous seizures (Scharfman, 2008).
Mechanism of disease: genetic causes, developmental disorders or malformations, response to insult or injury.
Treatment: few common seizure-preventing drugs, as well as surgical intervention if treatment by medication fails (Epilepsy Foundation of America).
C. elegans as a model for epilepsy: still in its infancy. However, there are a few C. elegans epilepsy models (1) gain-of-function mutation in an acetylcholine receptor (2) lis-1 mutation which causes lissencephaly, an epilepsy-prone disease (3) mutations in genes involved in GABA synthesis resulting in convulsions (Cunliffe et al., 2015).
2. Brain tumors
Mechanism of disease: uncontrollable cell growth.
Treatment: treatment is dependent on the type of malignant tumor. For example, glioblastoma is one of the most aggressive forms of brain cancer, and treatment options include surgically removing the tumor and radiation and oral chemotherapy. However, this treatment is not curative, but standard of care can add approximately 1 year to life: maximal resection of the tumor adds approximately 9mths, radiation approximately 5mths and oral chemo approximately 9 weeks (Hopkins Medicine).
C. elegans as a model for brain cancer: human cell cycles genes implicated in tumor research have orthologs in C. elegans (Kirienko et al., 2010). If C. elegans are used in cancer research, they are most commonly used to understand cell fate changes when tumor-specific genes are mutated (Saito and van den Heuvel, 2002).
3. Parkinson’s disease
Mechanism of disease: selective cell death in which the dopaminergic neurons are lost (Cacabelos, 2017).
Treatment: Parkinson’s disease treats to lessen a patient’s symptoms, but there is no way to reverse the effects of the disease (Parkinson’s Foundation).
C. elegans as a model for Parkinson’s disease: specific genes have been discovered for monogenic, involving one gene, forms of Parkinson’s disease, allowing for the creation of C. elegans models where these genes are altered (Cooper and Van Raamsdonk, 2018).
4. Stroke
Mechanism of disease: interrupted or reduced blood flow to the brain causing brain cell death (Mayo Clinic, 2019).
Treatment: Strokes can be drug treated or treated with medical devices that help to remove the clotted blood vessel. Long-term effects are minimized the quicker medical intervention proceeds following the onset of a stroke (National Stroke Association).
C. elegans as a model for stroke: not generally used.
5. Alzheimer’s disease
Mechanism of disease: underlying molecular mechanisms are not fully understood but genetic, environmental and lifestyle factors have been implicated. A build up of amyloid plaques and neurofibrillary tangles are main features of the disease, but the precise cause of these build ups are not known.
Treatment: There are drug treatments available to lessen the symptoms of Alzheimer’s disease, although there is no cure (National Institute on Aging).
C. elegans as a model for Alzheimer’s disease: mutations in genes correlated with Alzheimer’s disease have orthologs in C. elegans, which can be used to model the disease (Alexander et al, 2014).