Biology subjects

Mahanty, S.

Publications and source records attributed to Mahanty, S..

4 recordsLinked to original sources

bioRxiv2026

Tubulin glycylation regulates microtubule-protein interactions that are key for ciliary stability and trafficking

Tubulin glycylation, a cilia-specific posttranslational modification is emerging as a potentially key regulator of ciliary axonemal microtubules. However, insights into the functional consequences of glycylation have remained limited. Here, using in vitro reconstitution assays with unmodified or custom-glycylated tubulin, we provide a systematic mechanistic analysis of glycylation-dependent regulation of motors and microtubule-associated proteins. Our studies highlight that glycylation selectively enhances ciliary kinesin-2 motility while reducing kinesin-1 activity, suggesting a role in promoting efficient intraflagellar transport along axonemal microtubules. Moreover, glycylation protects microtubules from decay by suppressing the activities of the depolymerase MCAK and severing enzyme spastin, thereby enhancing stability. Notably, this regulation is dependent on the proportion of glycylation on the microtubule surface, coupled with concomitant reduction of glutamylation. Thus, by generating microtubule surfaces with distinct biochemical states, we establish that combinatorial modification patterns define functional microtubule properties especially in cilia. Together, our findings provide the first comprehensive mechanistic framework for tubulin glycylation in regulating molecular motors and MAPs in cilia, establishing glycylation as a key determinant of motor selectivity and microtubule stability within the axoneme.

biochemistry↗

bioRxiv2022

Golgi apposition promotes the generation of specialized lysosomes in differentiated keratinocytes

Intracellular organelles support cellular physiology in diverse conditions. In the skin, epidermal keratinocytes undergo differentiation with gradual changes in cellular physiology, accompanying remodeling in lysosomes and the Golgi apparatus. However, the functional significance and the molecular link between lysosome and Golgi remodeling were unknown. Here, we show that in differentiated keratinocytes, the Golgi apparatus redistributes as ministacks leading to a significant increase in total protein secretion. The Golgi ministacks establish contact with lysosomes facilitated by Golgi tethering protein GRASP65, the depletion of which is associated with the loss of Golgi-lysosome contact and malformation of lysosomes defined by their aberrant morphology, size, and function. Strikingly, these lysosomes receive secretory Golgi cargoes, contribute to the protein secretion from the Golgi, and are critically maintained by the secretory function of the Golgi apparatus. We uncovered a novel mechanism of lysosome specialization through unique Golgi-lysosome contact that likely supports high secretion from differentiated keratinocytes. Key pointsO_LICalcium induced differentiation of human keratinocytes accompanies the dispersal of functional Golgi stacks and lysosomes. C_LIO_LIDispersed Golgi stacks establish contact/physical apposition with the lysosomes. C_LIO_LIGolgi tether GRASP65 surrounds keratinocyte lysosomes and facilitates Golgi-lysosome apposition. C_LIO_LIGRASP65 depletion abolishes Golgi-lysosome apposition and accumulates morphologically altered non-degradative lysosomes. C_LIO_LILysosomes of differentiated keratinocytes receive secretory Golgi cargo and contribute to the protein secretion from the Golgi. C_LIO_LISpecialized lysosomes are maintained by the secretory function of the Golgi apparatus. C_LI

cell biology↗

bioRxiv2019

Cestode larvae excite host neuronal circuits via glutamatergic signaling.

Neurocysticercosis (NCC) is caused by infection of the brain by larvae of the parasitic cestode Taenia solium. It is the most prevalent parasitic infection of the central nervous system and one of the leading causes of adult-acquired epilepsy worldwide. However, little is known about how cestode larvae affect neurons directly. To address this, we used whole-cell patch-clamp electrophysiology and calcium imaging in rodent and human brain slices to identify direct effects of cestode larval products on neuronal activity. We found that both whole cyst homogenate and excretory/secretory products of cestode larvae have an acute excitatory effect on neurons, which can trigger seizure-like events in vitro. Underlying this effect was cestode-induced neuronal depolarization, which was mediated by glutamate receptor activation but not by nicotinic acetylcholine receptors, acid-sensing ion channels nor Substance P. Glutamate-sensing fluorescent reporters (iGluSnFR) and amino acid assays revealed that the larval homogenate of the cestodes Taenia crassiceps and Taenia solium contained high concentrations of the amino acids glutamate and aspartate. Furthermore, we found that larvae of both species consistently produce and release these excitatory amino acids into their immediate environment. Our findings suggest that perturbations in glutamatergic signaling may play a role in seizure generation in NCC.

neuroscience↗

bioRxiv2018

A non-canonical lysosome biogenesis pathway generates Golgi-associated lysosomes during epidermal differentiation

Keratinocytes maintain epidermis integrity and function including physical and antimicrobial barrier through cellular differentiation. This process is predicted to be controlled by calcium ion gradient and nutritional stress. Keratinocytes undergo proteome changes during differentiation, which enhances the intracellular organelle digestion to sustain the stress conditions. However, the molecular mechanism between epidermal differentiation and organelle homeostasis is poorly understood. Here, we used primary neonatal human epidermal keratinocytes to study the link between cellular differentiation, signaling pathways and organelle turnover. Upon addition of calcium chloride (2 mM) to the culture medium, keratinocytes increased their cell size and the expression of differentiation markers. Moreover, differentiated keratinocytes showed enhanced lysosome biogenesis that was dependent on ATF6-arm of UPR signaling but independent of mTOR-MiT/TFE transcription factors. Furthermore, chemical inhibition of mTOR has increased keratinocyte differentiation and relocalized the MiT/TFE TFs to the lysosome membranes, indicating that autophagy activation promotes the epidermal differentiation. Interestingly, differentiation of keratinocytes resulted in dispersal of fragmented Golgi and lysosomes, and the later organelles showed colocalization with Golgi-tethering proteins, suggesting that these lysosomes possibly originated from Golgi, hence named as Golgi-associated lysosomes (GALs). Consistent to this prediction, inhibition of Golgi function using brefeldin A completely abolished the formation of GALs and the keratinocyte differentiation. Thus, ER stress regulates the biogenesis of GALs, which maintains keratinocyte differentiation and epidermal homeostasis.

cell biology↗