Madepalli Krishnappa Lakshmana

Research topics

Matched from this investigator's NIH project titles and abstracts.

• Alzheimer's and Dementia
• Addiction and Substance Use
• Neuroplasticity and Neural Repair
• Pain and Nociception
• Depression
• Developmental Cognitive Neuroscience
• Cognitive Aging

Active NIH awards

• Effect of small molecule activator of autophagy on insulin signaling, senescence, and neuropathology in mouse models of Alzheimer's disease

  1R61AG086971-01A1

  NIA · FY 2025 · $479K

  PROJECT SUMMARY Although Aduhelm and Leqembi were recently approved for treating Alzheimer's disease (AD) patients, the reversibility and long-term benefits to patients remain far from reality. Accumulating data suggest that insulin resistance and markers of senescence increase during normal aging and even more so in AD as reflected by colocalization of neurofibrillary tangles (NFTs) and senescence markers in the neurons of both AD patients and mouse models of AD. Also, the impaired autophagy-lysosome pathway (ALP) is known to accelerate senescence, and restoring ALP has been shown to reverse senescence. Therefore, ALP activators are predicted to be excellent drugs to ameliorate multiple pathologies of AD including senescence. Our recently published data suggest that TFEB, a master regulator of ALP, protein levels are reduced in AD brains, TFEB expression by genetic approach reduces lipofuscin, increases lysosome and mitochondria biogenesis, and improves cognition. Considering the enormous potential for TFEB activators, we developed a high-content screening assay and identified TPI-132 as a potent activator of TFEB and ALP. TPI-132 dose- dependently dephosphorylated TFEB, has relatively low toxicity, and rescues doxorubicin- and d-galactose- induced senescence in cell lines and primary neurons. However, TPI-132 has low brain penetration. We also found mTOR-independent and calcineurin-dependent mechanism of TPI-132 to dephosphorylate and activate TFEB. Interestingly, we found that TPI-132 administration in old 3xTg mouse model of AD rescued age- associated insulin resistance dose-dependently. More importantly, TPI-132 increased ADAM10/sAPPα levels in the mouse brain following chronic administration. Based on these data, we hypothesize that by modulating TFEB and autophagy activity, TPI-132 increases neuroprotection, mitigates insulin resistance and senescence thereby improving Alzheimer's pathology and cognition. Aim 1 is designed to hit to lead optimization to increase potency and brain permeability, by synthesizing six sets of new compounds with structural diversity. Two best compounds with increased TFEB activity, reduced toxicity, and improved brain penetration and solubility will be selected to test in Aim 2. In aim 2, the selected two analogs will be tested in primary neurons from AD mouse models and iPSC-derived neurons from AD patients on senescence, dendritic spines, and Aβ/tau pathology. In aim 3, TPI-132 and the two best analogs will be administered to 3xTg and PS19 mouse models of AD by i.p. injections at 2 ages, 11 and 17 months for one month. The compounds' effect on insulin tolerance, senescence, synapses, protein aggregates and ALP activity will be quantified and correlated with cognition and compound levels in the brain. TPI-132 is more promising than other reported TFEB activators because besides anti-senescence effects, it increases two powerful neuroprotective factors, ADAM10/sAPPα and thus can be further developed and tested in clinical trials in future studies as new class of drugs for AD.

• The potential benefits of autophagy activator TFEB in opioid use disorder in mice

  1R21DA060111-01

  NIDA · FY 2024 · $406K

  PROJECT SUMMARY In the United States, the prevalence of opioid use and opioid use disorder (OUD) more than doubled in recent years. There has been an increase in opioid-related overdose deaths with nearly 92,000 reported in 2020. This has led to an unprecedented current crisis of OUD and overdose deaths resulting from indiscriminate use of opiates. While opioids are potent analgesics and provide relief from pain, they are also prone to be addictive. This crisis is further worsened due to the availability of illicit and more potent synthetic opiates like Fentanyl. The current FDA-approved drugs for OUD are both inadequate and have adverse effects. Therefore novel mechanism-based drug discovery approaches are urgently required for OUD and also to prevent overdose deaths resulting from respiratory depression. The heritability of substance use disorder is estimated to be greater than 50% based on twin, family, and adoption studies, and yet few modulating genes have been evaluated. Mu-opioid receptor (MOR) signaling is the major pathway responsible for both pain relief and euphoric effects of opioids. It is important to note that morphine inhibits nuclear translocation of TFEB, a master regulator of the autophagy-lysosome pathway (ALP), thereby reducing autophagic activity. Interestingly, we also found that MOR is colocalized with TFEB in the subcellular neuronal membranes, and most importantly also physically interact with each other as shown by coimmunoprecipitations. Also, opioids induce significant damage to neurons with reduced synaptic plasticity, and TFEB is known to protect against neurodegeneration in vivo in the brain, especially the dopaminergic neurons. Even more important, the most frequent cause of overdose death due to opioids is opioid-induced respiratory depression (OIRD) as well as damage to the lung tissue. Interestingly, TFEB overexpression can decrease inflammation and mitochondrial damage in the lung tissue thereby protecting against acute lung injury. Based on this overwhelming evidence we hypothesize that “As a master regulator of ALP, TFEB plays a pivotal role in the mitigation of opioid tolerance and dependence by enhancing synaptic plasticity in the brain”. In specific aim 1, we will use SH-SY5Y cells and striatal primary neurons to verify whether TFEB overexpression or siRNA-mediated knockdown alters morphine-, fentanyl-, DAMGO, and Methadone-induced MOR desensitization, internalization, and stability. Specific aim 2 is an in vivo study designed to assess whether TFEB or its activator TPI-132 influences MOR agonist-induced analgesia, dependence, tolerance, respiratory depression, and withdrawal symptoms using flag-TFEB, TFEB-/- mice and wild-type mice after sub- chronic exposure to morphine and fentanyl. To increase rigor, we have included two cell types, multiple opioids, different time points, doses. If TFEB indeed mitigates opioid addiction and tolerance, TPI-132 that can activate TFEB and autophagy may be developed as novel and excellent therapy for OUD and overdose deaths

Earlier awards

• Targeting Inflammasome with stable endocannabinoid ligand AMG315. CRISPR/Cas9 and nanotechnology study in the context of HIV and cannabinoidFY 2024 · $370K