Biology subjects

Pekała, M.

Publications and source records attributed to Pekała, M..

3 recordsLinked to original sources

bioRxiv2025

Structural polymorphism of ex-vivo ALECT2 amyloid fibrils revealed by cryo-EM

ALECT2 amyloidosis is a rare systemic disease characterized by the pathological deposition of leukocyte cell-derived chemotaxin-2 (LECT2) as amyloid fibrils, primarily affecting the kidneys and liver. The molecular mechanisms underlying LECT2 aggregation remain poorly defined, hindering diagnostic and therapeutic development. Here, we present cryo-electron microscopy structures of ex-vivo ALECT2 fibrils extracted from a patients kidney. We identified three fibril polymorphs: a predominant single-protofilament morphology and two minor double-protofilament morphologies. The dominant single-protofilament morphology comprises the full-length 133-residue LECT2 protein and retains all three native disulfide bonds. Low-resolution reconstructions of double-protofilament morphologies suggest they adopt a similar fold to the single protofilament morphology, but form paired assemblies with different inter-filament interfaces. Mass spectrometry also reveals acetylation within the fibrils. These findings offer critical insights into the structural basis of ALECT2 amyloid formation and identify molecular features that could inform future diagnostic and therapeutic approaches.

biophysics↗

bioRxiv2024

Cryo-EM reveals that cardiac IGLV6-derived AL fibrils can be polymorphic

Immunoglobulin light chain (AL) amyloidosis is a systemic disorder caused by the misfolding and aggregation of free immunoglobulin light chains (LCs) secreted by abnormal plasma cells. The resulting amyloid fibrils deposit in multiple organs, leading to progressive dysfunction and increased morbidity and mortality. Despite recent advances, the molecular determinants of LC aggregation and phenotypic variability remain poorly understood. Structural characterization of ex-vivo fibrils provides key insights into these pathogenic processes. Here, we report cryo-electron microscopy structures of cardiac AL amyloid fibrils derived from an IGLV6 light chain. The fibrils display two distinct morphologies composed of single and double protofilaments, each adopting a previously unobserved fold. Comparison with previously reported AL fibril structures reveals that while individual mutations can alter the local conformation, IGLV6-derived fibrils share conserved structural motifs that may underlie common aggregation pathways. These findings expand the disease structural landscape and highlight sequence-dependent yet structurally constrained mechanisms of LC fibril formation.

molecular biology↗

bioRxiv2020

Serum response factor is essential for synaptic maturation in the hippocampus

Disturbances of gene expression patterns that occur during brain development can severely affect signal transmission, connectivity, and plasticity--key features that underlie memory formation and storage in neurons. Abnormalities at the molecular level can manifest as changes in the structural and functional plasticity of dendritic spines that harbor excitatory synapses. This can lead to such developmental neuropsychiatric conditions as Autism spectrum disorders, intellectual disabilities, and schizophrenia. The present study investigated the role of the major transcriptional regulator serum response factor (SRF) in synapse maturation and its impact on behavioral phenotypes. Using in vitro and in vivo models of early postnatal SRF deletion, we studied its influence on key morphological and physiological hallmarks of spine development. The elimination of SRF in developing neurons resulted in a phenotype of immature dendritic spines and impairments in excitatory transmission. Moreover, using a combination of molecular and imaging techniques, we showed that SRF-depleted neurons exhibited a lower level of specific glutamate receptor mRNAs and a decrease in their surface expression. Additionally, the early postnatal elimination of SRF in hippocampal CA1 excitatory neurons caused spine immaturity and a specific social deficit that is frequently observed in autism patients. Altogether, our data suggest that the regulation of structural and functional dendritic spine maturation begins at the stage of gene transcription, which underpins the crucial role of such transcription factors as SRF. Moreover, disturbances of the postnatal expression of SRF translate to behavioral changes in adult animals.

neuroscience↗