Monisha Patel's scientific contributions

Novel insights into the etiology of metabolic disorders have recently been uncovered through the study of metabolite amyloids. In particular, inborn errors of metabolism (IEMs), including gout, Lesch–Nyhan syndrome (LNS), xanthinuria, citrullinemia, and hyperornithinemia–hyperammonemia–homocitrullinuria (HHH) syndrome, are attributed to the dysfunction of the urea cycle and uric acid pathway. In this study, we endeavored to understand and mechanistically characterize the aggregative property exhibited by the principal metabolites of the urea cycle and uric acid pathway, specifically hypoxanthine, xanthine, citrulline, and ornithine. Employing scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), we studied the aggregation profiles of the metabolites. Insights obtained through molecular dynamics (MD) simulation underscore the vital roles of π–π stacking and hydrogen bonding interactions in the self-assembly process, and thioflavin T (ThT) assays further corroborate the amyloid nature of these metabolites. The in vitro MTT assay revealed the cytotoxic trait of these assemblies, a finding that was substantiated by in vivo assays employing the Caenorhabditis elegans (C. elegans) model, which revealed that the toxic effects were more pronounced and dose-specific in the case of metabolites that had aged via longer preincubation. We hence report a compelling phenomenon wherein these metabolites not only aggregate but transform into a soft, ordered assembly over time, eventually crystallizing upon extended incubation, leading to pathological implications. Our study suggests that the amyloidogenic nature of the involved metabolites could be a common etiological link in IEMs, potentially providing a unified perspective to study their pathophysiology, thus offering exciting insights into the development of targeted interventions for these metabolic disorders.

We report for the very first time the controlled structural changes in the self‐assemblies of N ‐(9‐fluorenylmethoxycarbonyl)‐ O ‐ tert ‐butyl‐ l ‐threonine (Fmoc‐Thr(tBu)‐OH) ( FTU ) to well defined unique morphologies. The self‐assembling properties of FTU were very interesting and intriguing as it resulted in the formation of unusual structures which resembles fibrous dumbbells and double‐sided broomstick‐like morphologies along with conventional spheres and rods under controlled conditions of concentration and temperature. The self‐assembly of other derivatives of threonine as well as another hydroxyl containing amino acid with same modification that is, (( N ‐(9H‐fluoren‐9‐yl)methoxy)carbonyl)‐ O ‐( tert ‐butyl)‐ l ‐serine (Fmoc‐Ser(tBu)‐OH) ( FSU ) was also studied to understand the crucial role of –Fmoc, ‐tBu and an additional –CH 3 group present in the structure of FTU in the process of self‐assembly. Solvent dependent morphological studies of FTU and FSU suggest important role of solubility parameters and crystallization in formation of these unusual structures. The control experiments of co‐incubation with tannic acid and urea and solution state ¹ H‐NMR studies elucidate π – π stacking interactions as the key driving force for the structure formation. Further, the interactions which can occur between pairs of FTU and FSU which cause initial self‐assembly was studied theoretically via computational modeling. These studies suggest pair of FTU can either interact via head‐to‐head (HH) or head‐to‐tail (HT) configurations and the most favorable probabilities of either of these interactions lead to morphological transitions in FTU self‐assembly under varying conditions. The studies reported herein hence demonstrate that bioorganic molecules like protected single amino acids can be efficiently used as scaffold for self‐assembly and provide a very simple and facile bottom‐up‐approach for the design of uncommon novel micro/nanoarchitects for multifarious applications.

Herein, we have studied the self-assembling and aggregation properties of Homogentisic acid (HA), N-acetyl aspartic Acid (NAA) and Isovaleric acid (IVA) with the aim to understand the effect of aggregation of these metabolites on the toxicities associated with rare metabolic diseases caused by their accumulation. To our surprise, we noted aggregation of HA, NAA and IVA follow amyloidogenic pathway and as these metabolites are aged small globules tend to merge and form fibrillar aggregates. These assemblies were characterized by conventional microscopy tools and their amyloidogenic nature was assessed by Thioflavin T binding assays. The cytotoxicity analysis by MTT assay suggest cellular viability was decreased in presence of metabolites in a dose dependent manner implicating their cytotoxic nature. Hence, the results presented in the manuscript are of significant interest as they can be of great practical implications in understanding the etiology/pathophysiology of rare metabolic diseases caused by the accumulation of these metabolites namely Alkaptonuria, Canavan diseases and Isovaleric academia from an amyloid perspective and may have possible implications in its therapeutic cure in future.

Aggregation of amino acids to amyloid like structures is known to have implications in the pathophysiology of single amino acid based inborn-errors of metabolism (IEMs). Studying the aggregation properties of amino acids is of crucial interest also to understand the etiology of these IEMs from an amyloid perspective. Hence, herein we have studied the self-assembly of different non-aromatic charged/uncharged polar amino acids namely L-Glutamine (Gln), L-Aspartic acid (Asp) L-Glutamic acid (Glu) L-Histidine (His), L-Arginine (Arg), L-Serine (Ser) and L-Threonine (Thr) whose amyloid characteristics have still not been explored by ageing them in aqueous solution for varying time intervals from 0-15 days.. Notably, of all amino acids glutamine revealed amyloid like fibrillar morphologies as observed in case of aromatic amino acids reported previously after ageing. Further, aspartic acid and glutamic acids also revealed uniform self-assembled morphologies after 10 days of ageing. The MTT assay also corroborated with microscopic observations and a relatively more cytotoxic nature of glutamine assemblies as compared to other amino acids could also be envisaged. The Thioflavin T binding assays suggest the structures formed by Gln, Asp and Glu may have amyloid nature. Hence, the results presented in this manuscript may have crucial implications in understanding the patho-physiology of IEMs caused by the excess of Gln, Asp and Glu and suggest a possible extension of generic amyloid hypothesis to these diseases.

Alkaptonuria is a rare inborn-error of metabolism caused by the accumulation of Homogentisic acid (HA).. Herein, we have studied the self-assembling and aggregation properties of HA with the aim to assess the effect of accumulation of HA inside the body. To our surprise, we noted aggregation of HA follows an amyloidogenic pathway and the fibrillar assemblies made from small globules are formed after ageing HA solution. These assemblies were characterized by conventional microscopy tools and their amyloidogenic nature was assessed by Thioflavin T binding assays. The cytotoxicity analysis by MTT assay suggest cellular viability was decreased in both mouse neuronal and normal fibroblast cells when they were co-incubated with the aged solution of HA. Hence, the results presented in the manuscript are of significant interest in understanding the etiology of alkaptonuria form an amyloid perspective and may have possible implication in its therapeutic cure in future

Aggregation of amino acids to amyloid like structures is known to have implications in the pathophysiology of single amino acids based inborn-errors of metabolism (IEMs). Studying the aggregation properties of amino acids is of crucial interest also to understand the association of these IEMs to amyloid associated diseases. Hence, herein we have studied the self-assembly of different non-aromatic charged/uncharged polar amino acids namely L-Glutamine (Gln), L-Aspartic acid (Asp), L-Glutamic acid (Glu) L-Histidine (His), L-Arginine (Arg), L-Serine (Ser) and L-Threonine (Thr) whose amyloid characteristics have still not been explored by ageing them for varying time intervals from 0-15 days in aqueous solution. The structure formation by the self-assembly of these amino acids were then studies by microscopy., Notably, of all amino acids glutamine revealed amyloid like febrile morphologies as observed in case of aromatic amino acids. The MTT assay also revealed a relatively more cytotoxic nature of glutamine assemblies as compared to other amino acid aggregates and suggests it may have amyloid like characteristics. Along with Gln, Asp and Glu also revealed formation of some unique self-assembled structures. The thioflavin T assay suggests these aggregates may have amyloid nature. Hence, the aggregation studies of these amino acids may have important implication in the pathogenesis of disease caused by the accumulation of glutamine, aspargine and aspartic acid.

Aggregation of amino acids to amyloid like structures is known to have implications in the pathophysiology of single amino acids based inborn-errors of metabolism (IEMs). Studying the aggregation properties of amino acids is of crucial interest also to understand the association of these IEMs to amyloid associated diseases. Hence, herein we have studied the self-assembly of different non-aromatic charged/uncharged polar amino acids namely L-Glutamine (Gln), L-Aspartic acid (Asp), L-Glutamic acid (Glu) L-Histidine (His), L-Arginine (Arg), L-Serine (Ser) and L-Threonine (Thr) whose amyloid characteristics have still not been explored by ageing them for varying time intervals from 0-15 days in aqueous solution. The structure formation by the self-assembly of these amino acids were then studies by microscopy., Notably, of all amino acids glutamine revealed amyloid like febrile morphologies as observed in case of aromatic amino acids. The MTT assay also revealed a relatively more cytotoxic nature of glutamine assemblies as compared to other amino acid aggregates and suggests it may have amyloid like characteristics. Along with Gln, Asp and Glu also revealed formation of some unique self-assembled structures. The thioflavin T assay suggests these aggregates may have amyloid nature. Hence, the aggregation studies of these amino acids may have important implication in the pathogenesis of disease caused by the accumulation of glutamine, aspargine and aspartic acid.

Herein, we report the aggregation properties of metabolites of urea cycle and uric acid pathway. The aggregation/ self-assembly properties of these metabolites were studied extensively via microscopic techniques. In this context the self-assembling properties of citrulline, ornithine, xanthine, hypoxanthine, cytosine and uracil were studied by assessing its aggregation under varying ageing time from fresh to day 15 of incubation. Interestingly, the metabolites exhibited tendency to aggregate and form soft fibril assembly during the course of ageing and gradually changes to crystalline structures on prolonged incubation. The results presented in this manuscript may have important implications in the pathogenesis of diseasescause urea and uric acid pathway metabolic dysfunction like HHH syndrome, Citrullinemia, Xanthinuria, Lesh Nyahn syndrome and Gout caused by accumulation of these metabolites.