Serasinghe, M. N. | Search bioRxiv

bioRxiv2026

A Human Recombinant Antibody Against DRP1 Serine 616 Phosphorylation Enables Detection of BRAFV600E-Associated Mitochondrial Division in Cancer

Mitochondria are dynamic organelles that continuously undergo balanced cycles of fusion and division to meet cellular demands. Mitochondrial division is mediated by Dynamin-Related Protein 1 (DRP1), a cytosolic large GTPase whose phosphorylation at serine 616 (DRP1-S616) promotes its translocation to the outer mitochondrial membrane and organelle division. Dysregulated, mitochondrial division disrupts cellular homeostasis and contributes to disease pathogenesis, including cancer. Our prior work demonstrated that the oncogene-induced mitogen-activated protein kinase (MAPK) pathway constitutively phosphorylates DRP1 at serine 616 (DRP1-S616), which is essential to cellular transformation and correlates with oncogene status in patient tissues. Similarly, DRP1-S616 is subject to pharmacologic control by targeted therapies against oncogenic MAPK signaling. Building upon this foundation, we developed a human recombinant monoclonal antibody with high specificity for DRP1-S616, referred to as 3G11. Using diverse biochemical platforms, we demonstrate the robust utility of 3G11 to detect DRP1-S616 in melanoma cell extracts and isolated organelles. Immunofluorescence revealed that pharmacologic inhibition of oncogenic MAPK signaling reduces DRP1-S616 levels which correlates with mitochondrial hyperfusion; while immunohistochemistry showed that elevated DRP1-S616 expression in human tissues correlates with BRAFV600E disease. Together, these findings establish 3G11 as a specific, versatile, renewable, and cost-effective tool for studying mitochondrial division, with strong potential for clinical applications.

cancer biology↗

bioRxiv2019

Repeated hypoglycemia blunts the responsiveness of glucose-inhibited GHRH neurons by remodeling neural inputs and disrupting mitochondrial structure and function.

Hypoglycemia is a frequent complication of diabetes, limiting therapy and increasing morbidity and mortality. With recurrent hypoglycemia, the counter-regulatory response (CRR) to decreased blood glucose is blunted, resulting in hypoglycemia unawareness. The mechanisms leading to these blunted effects remain incompletely understood. Here, we identify, with in situ hybridization, immunohistochemistry and the tissue clearing capability of iDisco, that GHRH neurons represent a unique population of arcuate nucleus neurons activated by glucose deprivation in vivo. Repeated glucose deprivation reduces GHRH neuron activation and remodels excitatory and inhibitory inputs to GHRH neurons. We show low glucose sensing is coupled to GHRH neuron depolarization, decreased ATP production and mitochondrial fusion. Repeated hypoglycemia attenuates these responses during low glucose. By maintaining mitochondrial length with the small molecule, mdivi-1, we preserved hypoglycemia sensitivity in vitro and in vivo. Our findings present possible mechanisms for the blunting of the CRR, broaden significantly our understanding of the structure of GHRH neurons and for the fist time, propose that mitochondrial dynamics play an important role in hypoglycemia unawareness. We conclude that interventions targeting mitochondrial fission in GHRH neurons may offer a new pathway to prevent hypoglycemia unawareness in diabetic patients.

physiology↗