Biology subjects

Agbas, A.

Publications and source records attributed to Agbas, A..

7 recordsLinked to original sources

bioRxiv2025

Platelet Bioenergetics Profiling Reveals Non-Mitochondrial Dysfunction as a Potential Biomarker of Diabetic Complications

Diabetes is associated with systemic bioenergetic dysfunction that contributes to complications such as diabetic peripheral neuropathy (DPN). While mitochondrial impairment has been implicated, the role of non-mitochondrial pathways is less clearly defined. To address this gap, we optimized platelet-based extracellular flux assays as a minimally invasive platform to study human bioenergetics. A seeding density of 20 x 106 platelets per well provided reliable respiratory measurements, consistent with the presence of 5-8 mitochondria per platelet. Platelets from both type 2 diabetes (T2D) and DPN patients demonstrated a significant reduction in non-mitochondrial oxygen consumption rate (OCR) compared with controls. This finding suggests impairment of oxygen-consuming processes beyond the mitochondria, likely reflecting diminished activity of oxidoreductase enzymes such as NADPH oxidases, cyclooxygenases, and lipoxygenases, which regulate redox balance, inflammatory signaling, and vascular tone. In contrast, basal and ATP-linked OCR were only marginally reduced in T2D and not significantly altered in DPN, indicating that mitochondrial-linked dysfunction may be more subtle or heterogeneous in these patient populations. The consistent decrease in non-mitochondrial OCR across both T2D and DPN highlights its potential as an early and sensitive indicator of systemic bioenergetic dysregulation in diabetes. These findings demonstrate that platelets are a practical and repeatable resource for assessing bioenergetics in humans. Diabetes impairs both mitochondrial and non-mitochondrial respiration, with the latter showing the most robust alterations. Reduced non-mitochondrial OCR may contribute independently to the pathogenesis of DPN and holds promise as a biomarker for prognosis and therapeutic monitoring in diabetic complications.

biochemistry↗

bioRxiv2023

The post-translational modification profile of TAR DNA-Binding Protein (TDP-43) in platelets of patients with Alzheimer's disease: An exploratory study for blood-based biomarker development.

The assignment of blood-based biomarkers for neurodegenerative diseases is of great clinical value. Well-developed and validated blood-based biomarkers can serve in early diagnosis and prognosis as well as aid in patient screening when recruiting for clinical trials. We attempted to establish a portfolio for post-translationally modified TAR DNA/RNA-binding protein (TDP-43), a regulator of nuclear transcription, in platelet cytosol obtained from patients with Alzheimers disease (AD) comparing to age-matched healthy subjects and a disease control cohort. We aimed to identify the most prominent post-translational modifications of TDP-43 as an AD-relevant biomarker and to demonstrate that such an assessment can be performed in peripheral blood. We have isolated TDP-43 protein from human platelet cytosol utilizing an Immunoaffinity chromatography. The eluates were immunoprobed with a series of antibodies raised against post-translationally modified proteins. We employed a capillary electrophoretic immunoassay (CEI) to assess the phosphorylated TDP-43 profile. We observed that SUMOylation, phosphorylation, ubiquitination, and cysteine oxidation of TDP-43 are more prominent in platelet cytosol of AD patients as compared to control subjects. These studies will pave the way for identifying disease-specific TDP-43 derivatives that can be potential biomarkers for early diagnosis and the development of therapeutics.

neuroscience↗

bioRxiv2021

Exosome TDP-43 profile in canine model of ALS: A preliminary study in developing surrogate biomarker

ObjectiveBlood-based biomarkers provide a crucial information in progress of neurodegenerative diseases with minimally invasive sampling method. Validated blood-based biomarker application in people with amyotrophic lateral sclerosis would derive numerous benefits. Canine degenerative myelopathy is a naturally occurring animal disease model to study the biology of human amyotrophic lateral sclerosis. Serum derived exosomes are potential carriers for cell-specific cargoes making them ideal venue to study biomarkers for a variety of diseases and biological processes. This study assessed the exosomal proteins that may be assigned as surrogate biomarker that may reflect biochemical changes in central nervous system. MethodsExosomes were isolated from canine serum using commercial exosome isolation reagents. Exosomes target proteins contents were analysed by Western blotting method. ResultsThe profiles of potential biomarker candidates in spinal cord homogenate and that of serum-derived exosomes were found elevated in dogs with degenerative myelopathy as compare to control subjects. ConclusionsSerum-derived exosomal biomolecules can serve as surrogate biomarkers in neuro degenerative diseases. Key MessagesO_LIA canine with degenerative myelopathy can serve as a model animal to study human amyotrophic lateral sclerosis. C_LIO_LISerum-derived exosomes contains Transactive Response DNA Binding Protein 43 (TDP-43), potential biomarker candidate. C_LIO_LIThe levels of spinal cord TDP-43 proteins and that of serum-derived exosomes exhibited a similar profiling. Therefore, serum derived exosomes may be used as a venue for establishing blood-based biomarkers for neurodegenerative diseases. C_LI

neuroscience↗

bioRxiv2021

Measuring mitochondrial electron transfer complexes in previously frozen cardiac tissue from the offspring of sow: A model to assess exercise induced mitochondrial bioenergetics changes

Measuring the mitochondrial electron transfer complex (ETC) profile from previously frozen heart tissue samples from offspring born to an exercised sow provided descriptive data about exercise-induced mitochondrial biochemical changes in heart tissue from the offspring born to the exercised sow. The hypothesis proposed and tested was that a regular maternal exercise of a sow during pregnancy would increase the mitochondrial efficiency of offspring heart bioenergetics. This hypothesis was tested by isolating mitochondria using a mild-isolation procedure to assess mitochondrial ETC and supercomplex profiles. The procedure described here allowed for the processing of previously frozen archived heart tissues and eliminated the necessity of fresh mitochondria preparation for the assessment of mitochondrial ETC complexes, supercomplexes, and ETC complex activity profiles. This protocol describes the optimal ETC protein complex measurement in multiplexed antibody-based immunoblotting and super complex assessment using blue-native gel electrophoresis. SUMMARYPreparation of mitochondria-enriched samples from previously frozen archived solid tissues allowed the investigators to perform both functional and analytical assessments of mitochondria in various experimental modalities. This study demonstrates how to prepare mitochondria-enriched preparations from frozen heart tissue and perform analytical assessments of mitochondria.

biochemistry↗

bioRxiv2019

Platelet proteolytic machinery assessment in Alzheimer’s Diseases

AimPlatelets provide substantial information about the proteolytic system profile in neurodegenerative diseases. Assessment of autophagy and proteasome target proteins in platelets may reflect tissue proteolytic machinery profile in central nervous system in Alzheimers diseases (AD). We aimed to demonstrate the optimum assay conditions and identify target proteins in platelet proteolytic machinery. MethodsPlatelet samples were obtained from clinically verified AD patients and age-matched non-demented control subjects that were recruited by University of Kansas Alzheimers disease Center. Autophagosome participating proteins in platelets were identified by Western blotting analysis. Standard gel electrophoresis and electro transfer apparatus were used for protein transfer onto the membrane. Several antibodies were tested to identify the best working antibodies, and their concentrations were optimized. An ELISA kit was used for platelet proteasome protein determination. Infrared imaging technology was used for visualizing the proteins on the membrane. ResultsAutophagosome participating proteins showed elevated levels in AD patient platelet cytosol. Only LC3-I autophagosome protein levels were significantly elevated. The concentrations of platelet lysate proteasome were assessed. AD patients proteasome levels were elevated but they were statistically not important as compared to controls. ConclusionsPlatelets can be used for assessing whether proteolytic system is functional. Blood-based sampling from human donors is less-invasive and analyzing platelet proteolytic system profile may help to develop pharmaceutical intervention approaches for neurodegenerative diseases in general.

neuroscience↗

bioRxiv2017

Impaired Cu-Zn superoxide dismutase (SOD1) and calcineurin (Cn) interaction in ALS: A presumed consequence for TDP-43 and zinc aggregation in Tg SOD1G93A rodent spinal cord tissue.

Impaired interactions between Calcineurin (Cn) and (Cu/Zn) superoxide dismutase (SOD1) are suspected to be responsible for the formation of hyperphosphorylated protein aggregation in amyotrophic lateral sclerosis (ALS). Serine (Ser)-enriched TDP-43 protein aggregation appears in the spinal cord of ALS animal models, and may be linked to the reduced phosphatase activity of Cn. The mutant overexpressed SOD1G93A protein does not properly bind zinc (Zn) in animal models; hence, mutant SOD1G93A - Cn interaction weakens. Consequently, unstable Cn fails to dephosphorylate TDP-43 that yields hyperphosphorylated TDP-43 aggregates. Our previous studies had suggested that Cn and SOD1 interaction was necessary to keep Cn enzyme functional. We have observed low Cn level, increased Zn concentrations, and increased TDP-43 protein levels in cervical, thoracic, lumbar, and sacral regions of the spinal cord tissue homogenates. This study further supports our previous published work indicating that Cn stability depends on functional Cn-SOD1 interaction because Zn metal is crucial for maintaining the Cn stability. Less active Cn did not efficiently dephosphorylate TDP-43; hence TDP-43 aggregations appeared in the spinal cord tissue.

neuroscience↗

bioRxiv2017

Platelet phosphorylated TDP-43: An exploratory study for a peripheral surrogate biomarker development for Alzheimer’s disease

Aim: Alzheimers disease (AD) and other forms of dementia create a non-curable disease population in Worlds societies. To develop a blood-based biomarker is important so that the remedial or disease-altering therapeutic intervention for AD patients would be available at the early stage. Materials & Methods: TDP-43 levels were analyzed in post-mortem brain tissue and platelets of AD and control subjects. Results: We observed an increased TDP-43 (<60%) in post-mortem AD brain regions and similar trends were also observed in patients platelets. Conclusion: Platelet TDP-43 could be used as a surrogate biomarker that is measurable, reproducible, and sensitive for screening the patients with some early clinical signs of AD and can be used to monitor disease prognosis.\n\nLay abstractIn this study, we explore to identify an Alzheimers disease-selective phospho-specific antibody that recognizes the diseased form of TDP-43 protein in patients blood-derived platelets. Our results suggest that selective anti-phosphorylated TDP-43 antibody discriminates Alzheimers disease from non-demented controls and patients with amyotrophic lateral sclerosis. Therefore, platelet screening with a selective antibody could potentially be a useful tool for diagnostic purposes for Alzheimers disease.

neuroscience↗