Faculty Bibliography

Transcripts of the KRAS locus are alternatively spliced to generate two proteins, KRAS4A and KRAS4B, which differ in their membrane-targeting sequences. These splice variants have been conserved for more than 450 million years, suggesting non-overlapping functions driven by differential membrane association. Here, we use proximity labeling to map the differential interactomes of the KRAS splice variants. We find 24 and 10 proteins that interact specifically with KRAS4A or KRAS4B, respectively. The KRAS interacting protein most specific to KRAS4A is BIRC6, a large member of the inhibitor of apoptosis protein family unique in possessing E2/E3 ubiquitin ligase activity. We find that this interaction takes place on the Golgi apparatus and results in the mono- and di-ubiquitination of KRAS4A at lysines 128 and 147. Silencing BIRC6 diminishes GTP loading of and growth stimulation by KRAS4A but not KRAS4B. Thus, BIRC6 is a ubiquitin ligase that inhibits apoptosis and also modifies KRAS4A.

The subspecialty of neurocritical care has grown significantly over the past 40 years along with advancements in the medical and surgical management of neurological emergencies. The modern neuroscience intensive care unit (neuro-ICU) is grounded in close collaboration between neurointensivists and neurosurgeons in the management of patients with such conditions as ischemic stroke, aneurysmal subarachnoid hemorrhage, intracerebral hemorrhage, subdural hematomas, and traumatic brain injury. Neuro-ICUs are also capable of specialized monitoring such as serial neurological examinations by trained neuro-ICU nurses; invasive monitoring of intracranial pressure, cerebral oxygenation, and cerebral hemodynamics; cerebral microdialysis; and noninvasive monitoring, including the use of pupillometry, ultrasound monitoring of optic nerve sheath diameters, transcranial Doppler ultrasonography, near-infrared spectroscopy, and continuous electroencephalography. Neuro-ICUs are also capable of specialized neuroprotective management of medical complications, including sodium disorders, renal failure, respiratory failure, and hypertension. These units depend on an interdisciplinary team including speech and language pathologists, occupational and physical therapists, and social workers and case managers, who work to implement early mobilization and successful transition to rehabilitation centers. There are numerous models of neuro-ICUs ranging from "open" units in which patients are cared for in an ICU by an admitting attending, generally without involvement of an intensivist, to "semi-open" units in which intensivists act as consultants, to "closed" units in which the neurointensivist is the admitting attending. The utilization of neuro-ICUs is associated with improved outcomes including lower mortality rates, decreased ICU and hospital length of stay, and improved functional outcomes.

BACKGROUND:Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a recently described demyelinating disorder, and children represent about 50% of all cases. Almost half of the patients experience relapses, but very few studies have evaluated predictors of relapse risk, challenging clinical management. The study aimed to identify predictors at MOGAD onset that are associated with a relapsing course. METHODS:Prospectively collected data from paediatric patients with MOGAD seen by the US Network of Paediatric MS Centres were leveraged. Univariable and adjusted multivariable models were used to predict recurrent disease. RESULTS:We identified 326 MOGAD cases (mean age at first event 8.9 years [SD 4.3], 57% female, 77% white and 74% non-Hispanic) and 46% relapsed during a mean follow-up of 3.9 years (SD 4.1). In the adjusted multivariable model, female sex (HR 1.66, 95% CI 1.17 to 2.36, p=0.004) and Hispanic/Latino ethnicity (HR 1.77, 95% CI 1.19 to 2.64, p=0.005) were associated with a higher risk of relapsing MOGAD. Maintenance treatment initiated before a second event with rituximab (HR 0.25, 95% CI 0.07 to 0.92, p=0.037) or intravenous immunoglobulin (IVIG) (HR 0.35, 95% CI 0.14 to 0.88, p=0.026) was associated with lower risk of a second event in multivariable analyses. Conversely, maintenance steroids were associated with a higher estimated relapse risk (HR 1.76, 95% CI 0.90 to 3.45, p=0.097). CONCLUSION/CONCLUSIONS:Sex and ethnicity are associated with relapsing MOGAD. Use of rituximab or IVIG therapy shortly after onset is associated with a lower risk of the second event. Preventive treatment after a first event could be considered for those with a higher relapse risk.

While mostly de novo truncating variants in SCAF4 were recently identified in 18 individuals with variable neurodevelopmental phenotypes, knowledge on the molecular and clinical spectrum is still limited. We assembled data on 50 novel individuals with SCAF4 variants ascertained via GeneMatcher and personal communication. With detailed evaluation of clinical data, in silico predictions and structural modeling, we further characterized the molecular and clinical spectrum of the autosomal dominant SCAF4-associated neurodevelopmental disorder. The molecular spectrum comprises 25 truncating, eight splice-site and five missense variants. While all other truncating variants were classified as pathogenic/likely pathogenic, significance of one C-terminal truncating variant, one splice-site variant and the missense variants remained unclear. Three missense variants in the CTD-interacting domain of SCAF4 were predicted to destabilize the domain. Twenty-three variants occurred de novo, and variants were inherited in 13 cases. Frequent clinical findings were mild developmental delay with speech impairment, seizures, and skeletal abnormalities such as clubfoot, scoliosis or hip dysplasia. Cognitive abilities ranged from normal IQ to severe intellectual disability (ID), with borderline to mild ID in the majority of individuals. Our study confirms the role of SCAF4 variants in neurodevelopmental disorders and further delineates the associated clinical phenotype.

When we vocalize, our brain distinguishes self-generated sounds from external ones. A corollary discharge signal supports this function in animals; however, in humans, its exact origin and temporal dynamics remain unknown. We report electrocorticographic recordings in neurosurgical patients and a connectivity analysis framework based on Granger causality that reveals major neural communications. We find a reproducible source for corollary discharge across multiple speech production paradigms localized to the ventral speech motor cortex before speech articulation. The uncovered discharge predicts the degree of auditory cortex suppression during speech, its well-documented consequence. These results reveal the human corollary discharge source and timing with far-reaching implication for speech motor-control as well as auditory hallucinations in human psychosis.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Immune checkpoint inhibitors (ICIs) are increasingly used against various cancers but are associated with immune-related adverse events (irAEs). Risk of irAEs may be higher in patients with certain preexisting autoimmune diseases, and these patients may also experience exacerbation of the underlying autoimmune disease following ICI initiation. People with multiple sclerosis (MS) have mostly been excluded from clinical trials of ICIs, so data on the safety of ICIs in MS are limited. This study aims to assess the rate of MS activity, as well as neurologic and nonneurologic irAEs in persons with MS treated with ICIs for cancer. METHODS:Participating sites were invited to this retrospective observational study through the Medical Partnership 4 MS+ listserv. Seven large academic centers participated in the study, each conducting a systematic search of their electronic medical record system for patients with MS and history of ICI treatment. The participating neurologist reviewed each chart individually to ensure the inclusion criteria were met. Demographics and data on MS and cancer history, treatments, and outcomes were abstracted from patient charts using a structured instrument. RESULTS:We identified 66 people with MS (median age 66 years, 73% female, 68% not on disease-modifying therapy for MS) who were treated with ICIs for lung cancer (35%), melanoma (21%), or another oncologic indication. During post-ICI follow-up (median: 11.7 months, range 0.2-106.3 months), 2 patients (3%) had relapse or MRI activity, 3 (5%) had neurologic irAEs, and 21 (32%) had nonneurologic irAEs. At the last follow-up, 25 (38%) participants had partial or complete remission of their cancer, while 35 (53%) were deceased. DISCUSSION/CONCLUSIONS:In this multi-institutional systematic retrospective study of predominantly older patients with MS, most of whom were not on disease-modifying therapy, MS activity and neurologic irAEs following ICI treatment were rare. These data suggest that preexisting MS should not preclude the use of ICIs for cancer in older patients, but the results may not be generalizable to younger patients with active MS. Prospective studies of ICI safety that enroll younger patients with MS are needed.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Social determinants of health (SDOH) affect patient health outcomes, but the impact on patients with pediatric-onset multiple sclerosis (POMS) has not been well studied. Study objectives were to (1) describe the frequency of adverse SDOH, (2) evaluate social hardships as a potential barrier to the initiation of disease-modifying therapy (DMT), and (3) explore the association between adverse SDOH and disease outcomes in POMS, as well as study attrition. METHODS:This was a retrospective multicenter observational study conducted through the United States Network of Pediatric MS Centers database. Participants were patients diagnosed with POMS (excluding primary progressive MS). The primary outcome was time to initiation of DMT. Secondary outcomes included most recent Expanded Disability Status Scale (EDSS) score, steroid treatment for the first event, time to second event, and study attrition. Demographic variables and clinical outcomes were compared between patients with and without hardships (maternal education of high school or less, public insurance/no insurance, or single/no-income household). Multivariable regression models were used to assess the impact of social hardship on study outcomes. RESULTS:= 0.034). DISCUSSION/CONCLUSIONS:The experience of hardships is common and associated with younger age at symptom onset and diagnosis, as well as shorter time to second event. Lack of private insurance is associated with study attrition and a higher EDSS score despite no difference in time to initiating DMT. There may be differences in early disease pathophysiology related to social hardship, and future studies are needed to better understand this complex relationship.

Progressive supranuclear palsy (PSP) is a sporadic neurodegenerative tauopathy variably affecting brainstem and cortical structures, and characterized by tau inclusions in neurons and glia. The precise mechanism whereby these protein aggregates lead to cell death remains unclear. To investigate the contribution of these different cellular abnormalities to PSP pathogenesis, we performed single-nucleus RNA sequencing (snRNA-seq) and analyzed 50,708 high quality nuclei targeting the diencephalon, including the subthalamic nucleus and adjacent structures, from human post-mortem PSP brains with varying degrees of pathology compared to controls. Cell-type-specific differential expression and pathway analysis identified both common and discrete changes in numerous pathways previously implicated in PSP and other neurodegenerative disorders. This included EIF2 signaling, an adaptive pathway activated in response to diverse stressors, which was activated in multiple vulnerable cell types and validated in independent snRNA-seq and bulk RNA-seq datasets. Using immunohistochemistry, we found that activated eIF2α was positively correlated with tau pathology burden in vulnerable brain regions. Multiplex immunofluorescence localized activated eIF2α positivity to hyperphosphorylated tau (p-tau) positive neurons and ALDH1L1-positive astrocytes, supporting the increased transcriptomic EIF2 activation observed in these vulnerable cell types. In conclusion, these data provide insights into cell-type-specific pathological changes in PSP and support the hypothesis that failure of adaptive stress pathways play a mechanistic role in the pathogenesis and progression of PSP.

Increasing evidence points to a pivotal role of immune processes in the pathogenesis of Alzheimer disease, which is the most prevalent neurodegenerative and dementia-causing disease of our time. Multiple lines of information provided by experimental, epidemiological, neuropathological and genetic studies suggest a pathological role for innate and adaptive immune activation in this disease. Here, we review the cell types and pathological mechanisms involved in disease development as well as the influence of genetics and lifestyle factors. Given the decade-long preclinical stage of Alzheimer disease, these mechanisms and their interactions are driving forces behind the spread and progression of the disease. The identification of treatment opportunities will require a precise understanding of the cells and mechanisms involved as well as a clear definition of their temporal and topographical nature. We will also discuss new therapeutic strategies for targeting neuroinflammation, which are now entering the clinic and showing promise for patients.

Tumor associated epilepsy is a common and debilitating co-morbidity of brain tumors, for which inadequate treatments are available. Additionally, animal models suggest a potential link between seizures and tumor progression. Our group has previously described a mouse model of diffusely infiltrating glioma and associated chronic epilepsy. G protein-gated inwardly rectifying potassium (GIRK) channels are important regulators of neuronal excitability, but their development as a target of antiseizure medications has been hampered by cross-reactivity with GIRK channels in the heart. Recently GiGA1, a novel GIRK agonist that is highly selective for brain tissue, was developed and shown to have antiseizure properties in an acute chemoconvulsant model. Here, we test GiGA1 ex vivo in our established mouse model of tumor associated epilepsy, demonstrating that a highly selective, small-molecule GIRK agonist can reduce seizure-like activity in the peritumoral region, where neurons and glioma cells interact and from which focal seizures arise.