Research in the Rao Lab is agile and innovative. We invest in high risk/high reward projects that will push the boundaries of knowledge and cross fertilize between fields.

Research

The Rao Lab studies evolutionarily ancient but recently discovered ion pumps and transporters and their role in human health and disease. These include Golgi Ca²⁺-ATPases, lysosomal H⁺-ATPases, endosomal Na⁺/H⁺ exchangers. Our experimental reach is broad and multidisciplinary, harnessing the range of approaches to understand the cellular and molecular basis of a wide range of relevant disorders, including cancers of the brain and breast, neurological and metabolic disease. A brief overview of ongoing projects are listed below. Please refer to our publications page for past projects.

Organoid Models of Transport

To define the human “transportome”, we are developing human in vitro organoid models of specific tissues, including lactating mammary gland, to systematically de-orphanize understudied transporters and reveal potential new roles in nutrition and development. Our Transport Elucidation Center (TEC) funded by a UC2 grant from NIH/NICHD on Minerals In Nutrition and Development (MINeD) will capitalize on the rich scientific, clinical, and mentoring expertise of our collaborative team to serve as a hub for discovery, bench-to-bedside translation, and training in the area of human metal and ion transport and nutrient uptake.

Calcium Transport in Cancer, Cutaneous and Neurological Disease

hSPCA1 is the Golgi secretory pathway Ca²⁺-ATPase ubiquitously expressed in all tissues and essential for embryonic development and viability. Mutations in one allele give rise to the debilitating ulcerative skin disorder Hailey Hailey disease. We are using human immortalized keratinocyte models with CRISPR/Cas9 knockouts of one or both alleles of ATP2C1 to understand the pathophysiology of ulcerative skin disorders and explore therapeutic possibilities.

This work is funded by a R03 grant from NIH/NCATS.

hSPCA2 is a second calcium pump isoform with unusual properties of activating calcium channels on the plasma membrane and eliciting Ca²⁺ influx implicated in lactation and breast cancer. We are currently investigating cross-talk between Golgi-derived vesicles and other organelles including mitochondria.

Calcium dysregulation underlies many cellular phenotypes of early neurodegeneration, including Golgi fragmentation and ROS generation. We use models of ALS and Alzheimer disease to investigate the role of organellar Ca²⁺ in disease etiology.

This work is a collaboration with FVE Foundry.

Salt and pH Regulation by Sodium (Potassium)/Proton Exchangers

Two human endosomal Na⁺/H⁺ Exchanger (eNHE) isoforms – NHE6 (SLC9A6; Christianson Syndrome Protein) and NHE9 (SLC9A9; AUTS16), have been implicated in a plethora of neurological disorders including autism and intellectual disability. By linking endosomal pH to cargo trafficking and turnover, we show how loss of eNHE function and acidic endosomes promote amyloidogenesis in Alzheimer disease models, whereas gain of function and endosomal alkalization confers chemoradiation resistance and poor prognosis in brain cancer. We are excited to collaborate with the group of Yamuna Krishnan at U Chicago to develop new tools to quantitatively assess and manipulate the ionic milieu in endosomes.

Ongoing and planned studies will develop spatially localized and NHE isoform-selective inhibitors, explore phenotype-genotype relations using PheWAS analysis of human gene variants, and reveal organellar cross-talk between endosomes and mitochondria and their importance in energy metabolism. We work closely with the research group of Tooraj Mirshahi (Geisinger Clinic, Danville PA) on this project.

Our NHE project is funded by a multi-PI grant awarded to the Rao, Krishnan and Mirshahi groups by NIH/NIGMS.

NHA family of Na⁺, Li⁺/H⁺ Antiporters

Our phylogenetic analysis led to the unexpected discovery of a distinct clade of previously unrecognized transporters found in all metazoans, distantly linked to bacterial electrogenic NhaA antiporters. Represented by the NHA1-2 (SLC9B1-2) antiporters in humans, their function and mechanism are still emerging. We are pursuing the hypothesis that NHA2 is the elusive hypertension related locus identified by Na⁺/Li⁺ exchange activity, and is implicated in cyst formation in polycystic kidney disease.

We are thrilled to continue these studies through a subaward from the Maryland PKD Research and Translational Core Center.