Charles Shao

Postsynaptic degeneration as revealed by PSD-95 reduction occurs after advanced Aβ and tau pathology in transgenic mouse models of Alzheimer’s disease

Impairment of synaptic plasticity underlies memory dysfunction in Alzheimer’s disease (AD). Molecules involved in this plasticity such as PSD-95, a major postsynaptic scaffold protein at excitatory synapses, may play an important role in AD pathogenesis. We examined the distribution of PSD-95 in transgenic mice of amyloidopathy (5XFAD) and tauopathy (JNPL3) as well as in AD brains using double-labeling immunofluorescence and confocal microscopy. In wild type control mice, PSD-95 primarily labeled neuropil with distinct distribution in hippocampal apical dendrites. In 3-month-old 5XFAD mice, PSD-95 distribution was similar to that of wild type mice despite significant Aβ deposition. However, in 6-month-old 5XFAD mice, PSD-95 immunoreactivity in apical dendrites markedly decreased and prominent immunoreactivity was noted in neuronal soma in CA1 neurons. Similarly, PSD-95 immunoreactivity disappeared from apical dendrites and accumulated in neuronal soma in 14-month-old, but not in 3-month-old, JNPL3 mice. In AD brains, PSD-95 accumulated in Hirano bodies in hippocampal neurons. Our findings support the notion that either Aβ or tau can induce reduction of PSD-95 in excitatory synapses in hippocampus. Furthermore, this PSD-95 reduction is not an early event but occurs as the pathologies advance. Thus, the time-dependent PSD-95 reduction from synapses and accumulation in neuronal soma in transgenic mice and Hirano bodies in AD may mark postsynaptic degeneration that underlies long-term functional deficits.

Atypical Protein Kinase C in Neurodegenerative Disease I: PKMζ Aggregates With Limbic Neurofibrillary Tangles and AMPA Receptors in Alzheimer Disease

Protein kinase M&zgr; (PKM&zgr;), an atypical protein kinase C (PKC) isoform, plays a key role in the maintenance of long-term potentiation (LTP), a persistent enhancement of AMPA receptor-mediated synaptic transmission, as well as in the persistence of memory in Drosophila. Because memory impairment in Alzheimer disease (AD) has been attributed to disruption of synaptic plasticity, we investigated the expression and distribution of PKM&zgr; in this disorder. We found that PKM&zgr; accumulated in neurofibrillary tangles (NFTs), whereas conventional and novel PKC isoforms did not. Unlike tau, which is present in all NFTs regardless of location, PKM&zgr; was found in a subset of NFTs restricted to limbic or medial temporal lobe structures (i.e. hippocampal formation, entorhinal cortex, and amygdala), areas implicated in memory loss in AD. Interestingly, PKM&zgr; was not identified in any NFTs in control brains derived from 6 elderly individuals without known cognitive impairment. In medial temporal lobe structures in AD, PKM&zgr; also occurred within abnormal neurites expressing MAP2, GluR1 and GluR2 as well as in perisomatic granules expressing GluR1 and GluR2, suggesting that aggregation of PKM&zgr; disrupts glutamatergic synaptic transmission. Together, these findings suggest a link between PKM&zgr;-mediated synaptic plasticity and memory impairment in AD.

Atypical Protein Kinase C in Neurodegenerative Disease II: PKCι/λ in Tauopathies and α-Synucleinopathies

To study the role of atypical protein kinase C (aPKC) in neurodegenerative disease, we investigated the distribution of PKC&igr;/&lgr;, an aPKC isoform, in a variety of tauopathies and &agr;-synucleinopathies. Immunohistochemical study revealed PKC&igr;/&lgr; within tau-positive neurofibrillary inclusions in Alzheimer disease (AD), progressive supranuclear palsy, corticobasal degeneration (CBD), and Pick disease (PiD), within &agr;-synuclein-positive Lewy bodies in idiopathic Parkinson disease and dementia with Lewy bodies, as well as within glial inclusions in multisystem atrophy. We also observed PKC&igr;/&lgr; label of actin-rich Hirano bodies in AD, PiD, and elderly individuals. Double immunolabeling and fluorescence resonance energy transfer demonstrated close physical association between PKC&igr;/&lgr; and phospho-tau or &agr;-synuclein in some neurofibrillary tangles and Lewy bodies. Furthermore, PKC&igr;/&lgr; colocalized with p62, a chaperone protein that binds to both aPKC and ubiquitin, in most of these inclusions. PKC&igr;/&lgr; also closely associated with the inactivated form of glycogen synthase kinase-3&bgr;, GSK-3&bgr;[ser9]. Together, these findings suggest that PKC&igr;/&lgr; may play a role in common mechanisms involving the pathogenesis of neurodegenerative disease.

PKMζ is necessary and sufficient for synaptic clustering of PSD-95.

The persistent activity of protein kinase Mzeta (PKMζ), a brain‐specific, constitutively active protein kinase C isoform, maintains synaptic long‐term potentiation (LTP). Structural remodeling of the postsynaptic density is believed to contribute to the expression of LTP. We therefore examined the role of PKMζ in reconfiguring PSD‐95, the major postsynaptic scaffolding protein at excitatory synapses. In primary cultures of hippocampal neurons, PKMζ activity was critical for increasing the size of PSD‐95 clusters during chemical LTP (cLTP). Increasing PKMζ activity by overexpressing the kinase in hippocampal neurons was sufficient to increase PSD‐95 cluster size, spine size, and postsynaptic AMPAR subunit GluA2. Overexpression of an inactive mutant of PKMζ did not increase PSD‐95 clustering, and applications of the ζ‐pseudosubstrate inhibitor ZIP reversed the PKMζ‐mediated increases in PSD‐95 clustering, indicating that the activity of PKMζ is necessary to induce and maintain the increased size of PSD‐95 clusters. Thus the persistent activity of PKMζ is both necessary and sufficient for maintaining increases of PSD‐95 clusters, providing a unified mechanism for long‐term functional and structural modifications of synapses.

A Rare Case of Renal Cell Carcinoma With Leiomyomatous Stroma and Concomitant Ruptured Adrenal Aneurysm

Here we report a rare case of coexisting renal cell carcinoma (RCC) with leiomyomatous stroma and a ruptured adrenal aneurysm. The patient was a 75-year-old woman with acute abdominal pain. Imaging studies showed a left peri-renal hematoma and a mass in the left kidney. Left nephrectomy and adrenalectomy were performed. Pathological examination showed a ruptured aneurysm in the left adrenal gland. The renal mass was composed of tubules and acini of epithelial cells and a prominent leiomyomatous stroma. The tumor cells were positive for carbonic anhydrase IX, cytokeratin 7, and negative for AMACR, consistent with clear cell (tubulo) papillary RCC.

Brain pathology case of the month ‐ July 2016 – case 2 A 49‐Year‐old man with progressive cranial neuropathies

A 49-year-old man presented with a 2-month history of headache and recent 20-pound weight loss. He was diagnosed with cluster headaches at an outside hospital and treated with triptans. One week after the initial onset of headache, he developed right jaw and facial pain with facial weakness, accompanied by inability to fully close his right eye and mouth. He was given one dosage of steroids at an outside hospital for cluster headache with full resolution of his symptoms. However, a week later, his right facial weakness recurred and persisted. About 4 weeks later, he complained about similar jaw/ facial pain and weakness of his left side, which appeared to be more severe than those of his right side. He also developed occasional diplopia on far gaze and left lateral gaze. He did not experience any changes in hearing or taste. Magnetic resonance imaging of brain revealed abnormal enhancement of the third, fifth, seventh and eighth cranial nerves with various degree of diffuse enlargement (arrows pointing to trigeminal nerves in Figure 1a). Patchy enhancement of the nerve roots in the distal lumbar region was also noted. A gallium whole body scan did not reveal any significant abnormality. Repeated CSF studies showed low glucose levels, elevated protein levels and elevated cell counts. Extensive peripheral blood and CSF work-up for infectious disease, autoimmune, demyelinating disorders and neoplasia were negative except for a positive T-cell lymphotropic virus type 1 (HTLV-1) antibody. His HIV-1/2 ELISA was negative. Peripheral blood flow cytometry showed mature WBCs with slightly elevated CD4 : CD8 ratio. CSF flow cytometry revealed large granular T-cell lymphocytosis consisting of CD3/ CD56/CD571 lymphocytes (>97% of gated lymphocytes), which was interpreted as due to a reactive process. A working diagnosis of neurosarcoidosis was made and the patient was treated with prednisone 60 mg daily for two weeks followed by dexamethasone 4 mg daily for another two weeks. However, the patient’s symptoms worsened, leading to heightened suspicion of a malignant neoplasm. Dexamethasone was discontinued and he subsequently underwent biopsy of the enlarged left infraorbital nerve (Figure 1b, arrows).

A 49-Year-Old Man with Progressive Cranial Neuropathies: Correspondence

A 49-year-old man presented with a 2-month history of headache and recent 20-pound weight loss. He was diagnosed with cluster headaches at an outside hospital and treated with triptans. One week after the initial onset of headache, he developed right jaw and facial pain with facial weakness, accompanied by inability to fully close his right eye and mouth. He was given one dosage of steroids at an outside hospital for cluster headache with full resolution of his symptoms. However, a week later, his right facial weakness recurred and persisted. About 4 weeks later, he complained about similar jaw/ facial pain and weakness of his left side, which appeared to be more severe than those of his right side. He also developed occasional diplopia on far gaze and left lateral gaze. He did not experience any changes in hearing or taste. Magnetic resonance imaging of brain revealed abnormal enhancement of the third, fifth, seventh and eighth cranial nerves with various degree of diffuse enlargement (arrows pointing to trigeminal nerves in Figure 1a). Patchy enhancement of the nerve roots in the distal lumbar region was also noted. A gallium whole body scan did not reveal any significant abnormality. Repeated CSF studies showed low glucose levels, elevated protein levels and elevated cell counts. Extensive peripheral blood and CSF work-up for infectious disease, autoimmune, demyelinating disorders and neoplasia were negative except for a positive T-cell lymphotropic virus type 1 (HTLV-1) antibody. His HIV-1/2 ELISA was negative. Peripheral blood flow cytometry showed mature WBCs with slightly elevated CD4 : CD8 ratio. CSF flow cytometry revealed large granular T-cell lymphocytosis consisting of CD3/ CD56/CD571 lymphocytes (>97% of gated lymphocytes), which was interpreted as due to a reactive process. A working diagnosis of neurosarcoidosis was made and the patient was treated with prednisone 60 mg daily for two weeks followed by dexamethasone 4 mg daily for another two weeks. However, the patient’s symptoms worsened, leading to heightened suspicion of a malignant neoplasm. Dexamethasone was discontinued and he subsequently underwent biopsy of the enlarged left infraorbital nerve (Figure 1b, arrows).

Abstract B63: Receptor status in early-onset breast cancer across races.

Breast cancer is a heterogeneous disease and, racial disparity of breast cancer has been known to influence the age of occurrence, prognosis and response to the treatment. The objective of this study is to analyze the variations in the expression of the receptor proteins- estrogen receptor (ER), progesterone receptor (PR) and HER-2/neu, in early onset breast cancer cross races. Data was collected by reviewing patient charts obtained from the participating institutions and was stratified according to age (Younger group: 40 year old and younger women; older age group: greater than 40 year old women), races (Caucasian, African American, Hispanic, Chinese and Indian), receptor status (ER, PR and HER-2) according to Luminal A, B, HER-2 and Triple Negative Breast Cancer (TNBC) subtypes, grade and stage. Results show that while African American women have higher percentage of TNBC than the Caucasian, there are evident variations in receptor status among other races. In Chinese woman of younger age group, 18.2% presented with TNBC subtype. However, in the same group, the HER-2 overexpression (ER-/PR-, HER-2+), luminal A (ER+/PR+, HER2-) and B (ER+/PR+, HER2+) subtypes were 9.1%, 45.5% and 9.0% respectively. In Indian women, TNBC has been found to be about 1.5 folds higher in younger age group (34 %) than older group (23 %) while HER-2 overexpression and the luminal A and B subgroups were 14.3%, 42.2% and 9.5%, respectively, somewhat similar to those in Chinese women. Our preliminary findings demonstrated that the expression of receptor proteins (ER, PR and Her-2/neu) in early onset breast cancer differs among different ethnic or racial women, suggesting a biological basis of distinct prognosis or therapeutic response related to racial disparities. This study will help to develop optimal personalized management strategies for breast cancer cross the races. Citation Format: Mandeep Singh,, Yi Ding, Liying Zhang, Susan Lee, Dong Song, Shruti Grover, Dinesh Chandra Doval, Dara S. Ross, Charles Shao, Changcheng Zhu, Ruliang Xu, Zili He, David Zhang, Jinhua Wang, Victor Chang, Margaret Chen, Phyllis August, Peng Lee,,. Receptor status in early-onset breast cancer across races. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr B63.

The postsynaptic density protein, PSD-95, coexists with neuropathological changes in 5XFAD and P301L transgenic mice

Background: Impairment of synaptic plasticity is believed to underlie memory dysfunction in Alzheimer’s and other dementing illnesses. Molecules involved in synaptic plasticity may, therefore, play important roles in pathogenesis and offer clues for treatment. PSD-95 is the major scaffold protein that controls NMDA and AMPA receptors at excitatory synapses and is essential for long term potentiation (LTP) and long term depression (LTD). Surprisingly, the role of PSD-95 in neurodegenerative diseases has not been extensively investigated. Methods: We examined brain tissue from two transgenic mouse models: 5XFAD for amyloidopathy and JNPL3 P301L for tauopathy using double-labeling immunofluorescence and confocal microscopy. Results: In 5XFAD mice, PSD-95 colocalized with amyloid-b (Ab), primarily within the center of plaque cores. A similar staining was noted for MAP-2, another dendritic protein. In addition, PSD-95 immunopositivity increased in neuronal soma adjacent to Ab plaques. In JNPL3 mice, both PSD-95 and tau accumulated in neuronal cell bodies, especially in hippocampal pyramidal neurons. Interestingly, PSD-95 and tau were located in disparate neurons in close proximity to one another. MAP-2, on the other hand, did not colocalize with either PSD-95 or tau in this model. In wild-type animals, PSD-95 had a typical synaptic pattern without any build-up within soma. Conclusions: Accumulation of PSD-95 in plaques and neuronal cell bodies in 5XFAD mice may represent an Ab-induced degenerative change. Similarly, build-up of PSD-95 in subsets of neurons in JNPL3 mice may be indicative of tauopathy-related toxicity. Taken together, the abnormal redistribution of PSD-95 to neuronal soma may lead to synaptic dysfunction at dendritic spines and thus could impede memory function in both amyloidopathy and tauopathy.