Biology subjects

Jayaram, N.

Publications and source records attributed to Jayaram, N..

2 recordsLinked to original sources

bioRxiv2026

COP9 complex maintains neuroblast growth and proliferation by regulating Akt/mTor pathway

The nervous system consists of the brain and associated structures that are replete with highly specialised neurons and glia. Central to the development of the brain are Neural Stem Cells, which self-renew to maintain their number and also give rise to differentiated progeny. To identify genes involved in the maintenance of Drosophila neural stem cells, neuroblasts, we performed a protein expression screen followed by a protein knockdown screen using deGradFP system. Through this, we identified CSN7, a COP9 signalosome (CSN) subunit, which is enriched in neuroblasts and essential for neural development. CSN is a highly conserved multi-protein complex that regulates proteasome-mediated protein degradation via modulation of Cullin-RING E3 ligases. We found that loss of CSN7 and CSN1b lead to a decrease in neuroblast size and a reduced mitotic index. Our results show that CSN7/CSN1b regulates Akt-TOR signalling in the developing larval brain. Furthermore, we found that this regulation is mediated by Cul1. Overall, our work describes a hitherto undescribed role for the components of the CSN complex in neural development.

developmental biology↗

bioRxiv2023

DYRK1A interacts with Tuberous Sclerosis complex and promotes mTORC1 activity

DYRK1A, a ubiquitously expressed kinase, is linked to the dominant intellectual developmental disorder, microcephaly and Down syndrome in humans. It regulates numerous cellular processes such as cell cycle, vesicle trafficking and microtubule assembly. DYRK1A is a critical regulator of organ growth; however, how it regulates organ growth is not fully understood. Here, we show that the knockdown of DYRK1A results in reduced cell size, which depends on mTORC1. Using proteomic approaches, we found that DYRK1A interacts with the Tuberous sclerosis complex (TSC) proteins, namely TSC1 and TSC2, which negatively regulate mTORC1 activation. Further, we show that DYRK1A phosphorylates TSC2 at T1462, a modification known to inhibit TSC activity and promote mTORC1 activity. We also found that the reduced cell growth upon knockdown of DYRK1A can be rescued by overexpression of RHEB, an activator of mTORC1. Our findings suggest that DYRK1A inhibits TSC complex activity through inhibitory phosphorylation on TSC2, thereby promoting mTORC1 activity. Further, using the Drosophila neuromuscular junction as a model, we show that the mnb, the fly homologues of DYRK1A, is rescued by RHEB overexpression, suggesting a conserved role of DYRK1A in TORC1 regulation.

molecular biology↗