Molecular determinants of the crosstalk between endosomal microautophagy and chaperone-mediated autophagy

Chaperone-mediated autophagy (CMA) and endosomal microautophagy (eMI) are pathways for selective degradation of cytosolic proteins in lysosomes and late endosomes, respectively. These autophagic processes share as a first step the recognition of the same five-amino-acid motif in substrate proteins by the Hsc70 chaperone, raising the possibility of coordinated activity of both pathways. In this work, we show the existence of a compensatory relationship between CMA and eMI and identify a role for the chaperone protein Bag6 in triage and internalization of eMI substrates into late endosomes. Association and dynamics of Bag6 at the late endosome membrane change during starvation, a stressor that, contrary to other autophagic pathways, causes a decline in eMI activity. Collectively, these results show a coordinated function of eMI with CMA, identify the interchangeable subproteome degraded by these pathways, and start to elucidate the molecular mechanisms that facilitate the switch between them.

In-silico screening and molecular dynamics simulation of quinazolinone derivatives as PARP1 and STAT3 dual inhibitors: a novel DML approaches

Modern cancer therapy now routinely employs the blocking of many oncoproteins or pathways. With two or more medicines, multiple inhibitions are often accomplished via DML techniques. In this study, we developed 30 quinazolinone derivatives as PARP1 and STAT3 dual inhibitors using DML methods and these compounds were tested for their dual inhibitory effect on PARP1 and STAT3 using docking, MM-GBSA, and molecular dynamics simulation investigations. The docking studies of ligands against PARP1 and STAT3 were performed using the Glide module, in silico ADMET screening was performed using the quickprob module, binding energy calculation was performed using the Prime MM-GBSA module, MD simulation was performed using the Desmond module, and atomic charges were calculated using the Jaguar module of Schrodinger suite 2019-4. Of the substances studied, the derivative 1f has a considerable gliding score. The in silico ADMET characteristics are within the approved range. PRIME MM-GB/SA was used to compute the binding free energy, and the results are substantial. To investigate the dynamic behavior of the protein-ligand complex, compound 1f was subjected to MD simulation at 100 ns. The tested chemical 1f produced the greatest results in MD simulations and MM-GBSA calculations, indicating that this ligand can inhibit more effectively.Communicated by Ramaswamy H. Sarma.

A new functional role of mitochondria-anchored protein ligase in peroxisome morphology in mammalian cells

Mitochondria and peroxisomes are metabolically interconnected and functionally active subcellular organelles. These two dynamic organelles, share a number of common biochemical functions such as β-oxidation of fatty acids and detoxification of peroxides. The biogenesis and morphology of both these organelles in the mammalian cells is controlled by common transcription factors like PGC1α, and by a common fission machinery comprising of fission proteins like DRP1, Mff, and hFis1, respectively. In addition, the outer membrane mitochondria-anchored protein ligase (MAPL), the first mitochondrial SUMO E3 ligase with a RING-finger domain, also regulates mitochondrial morphology inducing mitochondrial fragmentation upon its overexpression. This fragmentation is dependent on both the RING domain of MAPL and the presence of the mitochondrial fission GTPase dynamin-related protein-1 (DRP1). Earlier studies have demonstrated that mitochondrial-derived vesicles are formed independently of the known mitochondrial fission GTPase, DRP1 are enriched for MAPL and are targeted to peroxisomes. The current study shows that MAPL regulates morphology of peroxisomes in a cell-type specific manner. Fascinatingly, the peroxisome elongation caused either due to silencing of DRP1 or by addition of polyunsaturated fatty acid, docosahexaenoic acid was blocked by overexpressing MAPL in mammalian cell lines. Furthermore, the transfection and colocalisation studies of MAPL with peroxisome membrane marker, PMP70, in different cell lines clearly revealed a cell-type specificity of transport of MAPL to peroxisomes. Previous work has placed the Vps35 (retromer component) as vital for delivery of MAPL to peroxisomes, placing the retromer as critical for the formation of MAPL-positive mitochondrial-derived vesicles. The results of polyethylene glycol-based cell-cell fusion assay signified that the enrichment of MAPL in peroxisomes is through vesicles and a retromer dependent phenomenon. Thus, a novel function for MAPL in peroxisomes is established to regulate peroxisome elongation and morphology under growth conditions and thus possibly modulate peroxisome fission.

Cytoplasmic poly (A)-binding protein critically regulates epidermal maintenance and turnover in the planarian Schmidtea mediterranea

Identifying key cellular events that facilitate stem cell function and tissue organization is crucial for understanding the process of regeneration. Planarians are powerful model system to study regeneration and stem cell (neoblast) function. Here, using planaria, we show that the initial events of regeneration, such as epithelialization and epidermal organization are critically regulated by a novel cytoplasmic poly A-binding protein, SMED-PABPC2. Knockdown of smed-pabpc2 leads to defects in epidermal lineage specification, disorganization of epidermis and ECM, and deregulated wound healing, resulting in the selective failure of neoblast proliferation near the wound region. Polysome profiling suggests that epidermal lineage transcripts, including zfp-1, are translationally regulated by SMED-PABPC2. Together, our results uncover a novel role for SMED-PABPC2 in the maintenance of epidermal and ECM integrity, critical for wound healing and subsequent processes for regeneration.

Efficient generation of diffraction-limited multi-sheet pattern for biological imaging

We demonstrate a new technique to generate multiple light-sheets for fluorescence microscopy. This is possible by illuminating the cylindrical lens using multiple copies of Gaussian beams. A diffraction grating placed just before the cylindrical lens splits the incident Gaussian beam into multiple beams traveling at different angles. Subsequently, this gives rise to diffraction-limited light-sheets after the Gaussian beams pass through the combined cylindrical lens-objective sub-system. Direct measurement of field at and around the focus of objective lens shows multi-sheet pattern with an average thickness of 7.5 μm and inter-sheet separation of 380 μm. Employing an independent orthogonal detection sub-system, we successfully imaged fluorescently-coated yeast cells (≈4  μm) encaged in agarose gel-matrix. Such a diffraction-limited sheet-pattern equipped with dedicated detection system may find immediate applications in the field of optical microscopy and fluorescence imaging.

Multispectral Bayesian reconstruction technique for real-time two color fluorescence microscopy

We have developed a real-time imaging method for two-color widefield fluorescence microscopy using a combined approach that integrates multi-spectral imaging and Bayesian image reconstruction technique.

Intermittent clobazam prophylaxis in hot water epilepsy is safe and effective: a prospective study

PURPOSE

To evaluate the role of intermittent prophylaxis with clobazam in the management of HWE in a long-term prospective study.

MATERIAL AND METHODS

Two hundred and sixty patients [M:F - 194:66] with HWE were recruited. Patients were divided into: (a) 'HWE alone' (n=198) - received intermittent clobazam prophylaxis, 1-1½h prior to hot water head bath (group A); (b) 62 patients (20.4%) with 'HWE with spontaneous seizures were treated with continuous AEDs along with intermittent clobazam therapy (group B).

RESULTS

Patients (n=198) in group A was followed for mean of 17.6 ± 10.6 months (range: 3-57). One hundred and forty seven patients (74.2%) had excellent response with complete seizure freedom with clobazam therapy while 12 (6.1%) had >75% reduction in seizure frequency. Remaining 39 (19.7%) required additional standard AED along with clobazam and 18 patients among them developed spontaneous/unprovoked seizure at follow up of 6.7 ± 4.1 months. Forty five patients in group B were seizure free while on continuous AEDs.

CONCLUSIONS

Intermittent clobazam prophylaxis prior to head water bath might be a preferred mode of treatment of pure HWE. Additional AEDs are required if they have associated non-reflex unprovoked seizure.

Idiopathic generalized epilepsy: Phenotypic and electroencephalographic observations in a large cohort from South India

PURPOSE

We studied the phenotype and electroencephalographic (EEG) features, and therapeutic aspects of idiopathic generalized epilepsies (IGEs) in South Indian population.

PATIENTS AND METHODS

This prospective cross-sectional hospital-based study was carried out on non-consecutive 287 patients (age 22.2 ± 7.7 years; M:F = 139:148) with IGE syndrome. Their clinical and EEG observations were analyzed.

RESULTS

Majority of the patients had onset of seizures <20 years of age (n = 178; 62%). Thirty one patients (10.8%) had family history of epilepsy. Nearly half of them (49.9%) had <5 years of duration of seizures. The type of IGEs included Juvenile myoclonic epilepsy (JME): 115 (40.1%); IGE with generalized tonic-clonic seizures (GTCS) only: 102 (39.02%); childhood absence epilepsy (CAE): 35 (12.2%); GTCS on awakening: 15 (5.2%); Juvenile absence epilepsy (JAE): 11 (3.8%); and unclassified seizures: 9 (3.1%). The triggering factors noted in 45% were sleep deprivation (20%), non-compliance and stress in 5% each. The EEG (n = 280) showed epileptiform discharges in about 50% of patients. Epileptiform discharges during activation was observed in 40/249 patients (16.1%): Hyperventilation in 32 (12.8%) and photic stimulation in 19 (7.6%). The seizures were well controlled with anti-epileptic drugs (AEDs) in 232 (80.8%) patients and among them, 225 (78.4%) patients were on monotherapy. Valproate (n = 131) was the most frequently prescribed as monotherapy.

CONCLUSIONS

This is one of the largest cohort of patients with IGE. This study reiterates the importance of segregating IGE syndrome and such analysis will aid to the current understanding and management.

Multidimensional data reconstruction for two color fluorescence microscopy

We propose an iterative data reconstruction technique specifically designed for multi-dimensional multi-color fluorescence imaging. Markov random field is employed (for modeling the multi-color image field) in conjunction with the classical maximum likelihood method. It is noted that, ill-posed nature of the inverse problem associated with multi-color fluorescence imaging forces iterative data reconstruction. Reconstruction of three-dimensional (3D) two-color images (obtained from nanobeads and cultured cell samples) show significant reduction in the background noise (improved signal-to-noise ratio) with an impressive overall improvement in the spatial resolution (≈250 nm) of the imaging system. Proposed data reconstruction technique may find immediate application in 3D in vivo and in vitro multi-color fluorescence imaging of biological specimens.

Spatial filter based 3D resolution improvement and polarization properties of multiphoton multiple-excitation-spot-optical microscopy

Three-dimensional (3D) resolution improvement in multi-photon multiple-excitation-spot-optical microscopy is proposed. Specially designed spatial filter is employed for improving the overall 3D resolution of the imaging system. An improvement up to a factor of 14.5 and sub-femto liter volume excitation is achieved. The system shows substantial sidelobe reduction (<4%) due to the non-linear intensity dependence of multiphoton process. Polarization effect on x-oriented and freely rotating dipoles shows dramatic change in the field distribution at the focal-plane. The resulting point-spread function has the ability to produce several strongly localized polarization dependent field patterns which may find applications in optical engineering and bioimaging.