Mutations in the human LMNA gene cause a collection of diseases called laminopathies, which includes muscular dystrophy and dilated cardiomyopathy. The LMNA gene encodes lamins, filamentous proteins that form a meshwork on the inner side of the nuclear envelope. How mutant lamins cause muscle disease is not well understood, and treatment options are currently limited. To understand the pathological functions of mutant lamins so that therapies can be developed, we generated new Drosophila models and human iPS cell-derived cardiomyocytes. In the Drosophila models, muscle-specific expression of the mutant lamins caused nuclear envelope defects, cytoplasmic protein aggregation, activation of the Nrf2/Keap1 redox pathway, and reductive stress. These defects reduced larval motility and caused death at the pupal stage. Patient-derived cardiomyocytes expressing mutant lamins showed nuclear envelope deformations. The Drosophila models allowed for genetic and pharmacological manipulations at the organismal level. Genetic interventions to increase autophagy, decrease Nrf2/Keap1 signaling, or lower reducing equivalents partially suppressed the lethality caused by mutant lamins. Moreover, treatment of flies with pamoic acid, a compound that inhibits the NADPH-producing malic enzyme, partially suppressed lethality. Taken together, these studies have identified multiple new factors as potential therapeutic targets for LMNA -associated muscular dystrophy.

Brain G-protein coupled receptors have been hypothesized to be potential targets for maintaining or restoring cognitive function in normal aged individuals or in patients with neurodegenerative disease. A number of recent reports suggest that activation of melanocortin receptors (MCRs) in the brain can significantly improve cognitive functions of normal rodents and of different rodent models of the Alzheimer’s disease. However, the potential impact of normative aging on the expression of MCRs and their potential roles for modulating cognitive function remains to be elucidated. In the present study, we first investigated the expression of these receptors in six different brain regions of young (6 months) and aged (23 months) rats following assessment of their cognitive status. Correlation analysis was further performed to reveal potential contributions of MCR subtypes to spatial learning and memory. Our results revealed statistically significant correlations between the expression of several MCR subtypes in the frontal cortex/hypothalamus and the hippocampus regions and the rats’ performance in spatial learning and memory only in the aged rats. These findings support the hypothesis that aging has a direct impact on the expression and function of MCRs, establishing MCRs as potential drug targets to alleviate aging-induced decline of cognitive function.

The nuclei of multinucleated skeletal muscles experience substantial external force during development and muscle contraction. Protection from such forces is partly provided by lamins, intermediate filaments that form a scaffold lining the inner nuclear membrane. Lamins play a myriad of roles, including maintenance of nuclear shape and stability, mediation of nuclear mechanoresponses, and nucleo-cytoskeletal coupling. Herein, we investigate how disease-causing mutant lamins alter myonuclear properties in response to mechanical force. This was accomplished via a novel application of a micropipette harpooning assay applied to larval body wall muscles of Drosophila models of lamin-associated muscular dystrophy. The assay enables the measurement of both nuclear deformability and intracellular force transmission between the cytoskeleton and nuclear interior in intact muscle fibers. Our studies revealed that specific mutant lamins increase nuclear deformability while other mutant lamins cause nucleo-cytoskeletal coupling defects, which were associated with loss of microtubular nuclear caging. We found that microtubule caging of the nucleus depended on Msp300, a KASH domain protein that is a component of the linker of nucleoskeleton and cytoskeleton (LINC) complex. Taken together, these findings identified residues in lamins required for connecting the nucleus to the cytoskeleton and suggest that not all muscle disease-causing mutant lamins produce similar defects in subcellular mechanics.

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Living systems are very smart chemists and about 700 million years ago when animal life started most small molecule synthesis was discontinued. Now we get most of our small molecules from our diet. Instead, animal life evolved much more robust nucleic acid, peptide and protein, sugar and lipid chemistries. Not surprisingly, most of our current small molecule drugs have toxicities and mostly treat symptoms of our degenerative diseases. Drugs for the future need to be composed from peptides, proteins, nucleic acids, sugars and lipids to minimize toxicities. Here we will briefly illustrate this approach utilizing the melanocortin system (five receptors) and its native precursor peptide ligands derived from proopiomelanocort in (POMC), a primordial animal system involved in most of the biological activities, critical to our survival and good health.The melanocortin system is composed of five receptors (MC1R, MC2R, MC3R, MC4R and MC5R) and are found throughout the body and brain. They are critical for most of the major biological functions critical for survival and good health including pigmentation, response to stress, feeding behavior, sexual behavior, immune response, inflammatory response, cardiovascular and kidney function and many others, some still being discovered. The endogenous peptide ligands for these receptors are derived from a single primordial gene POMC and include ACTH (specific for MC2R), α-, β-and γ-MSHs which interact with MC1R, MC3R, MC4R and MC5R, but they are nonselective and have very short half lives in vivo (a few minutes) and all are agonists. A major goal in this research is to develop novel, potent, receptor selective agonists and antagonists (orthosteric and allosteric) that are selective for these receptors and are more stable and bioavailable, and that can (or cannot) cross the blood brain barrier (1). Here we will briefly discuss our recent efforts toward these goals, using the full repertoire of approaches to peptide and peptidomimetic design we have developed over the past 40 years (2,3). These include computer based drug design, biophysical methods, conformational constraints, novel amino acids, novel cyclic systems, N-methylation and peptide mimetic design.In earlier studies, we designed a number of peptide analogues of α-MSH using these methods including [Nle 4 , D-Phe 7 ]α-MSH(MT-I, NDP-α-MSH) (Ac-Ser-Tyr-Ser-Nle-Glu-His-DPhe-Arg-Trp-Gly-Lys-Pro-Val-NH 2 , MT-II-(Ac-Nle-c[Asp-DPhe-Arg-Trp-Lys]-NH 2 ) and Shu-9119-(Ac-Nle-c[Asp-His-D-Nal(2')-Arg-Trp-Lys]-NH 2 . These are highly potent (nanomolar to subnanomolar),stable (2 hours to 2 days) and bioavailable. MT-II crosses the blood brain barrier, MT-I does not. Neither are receptor selective except that neither interacts with the MC2R. SHU-9119 is very unique being a nanomolar agonist at the MC1R and the MC5R and a potent antagonist at the MC3R and MC4R. These ligands have been widely used by us and worldwide to make many of the biological discoveries for the system including biological activities in the brain.