Biology subjects

Alam, S. S.

Publications and source records attributed to Alam, S. S..

4 recordsLinked to original sources

bioRxiv2026

Developmental pleiotropy revealed by mosaic heterozygous Snrpb deletion underlies CCMS-like axial skeletal defects

Cerebro-Costo-Mandibular Syndrome (CCMS) is a rare congenital disorder due to pathogenic variants in the core spliceosomal gene SNRPB. Affected individuals present with axial skeletal abnormalities, including cleft palate, micrognathia, posterior rib gaps, and a bell-shaped thorax. The molecular basis of these axial defects remains poorly understood, limiting the development of targeted interventions. To study the temporal and molecular requirements of SNRPB during axial development, we generated a mouse model of CCMS using an inducible Cre-lox system to conditionally delete Snrpb. Mosaic deletion of exons 2-3 of Snrpb after gastrulation resulted in the full spectrum of CCMS-like abnormalities, including micrognathia, posterior rib gaps and a reduced thoracic cavity. Despite normal somite morphology and patterning, transcriptomic analysis of E9.5 mutant somites revealed upregulation of p53 pathway genes and mis-expression of retinoic acid (RA) signaling components, consistent with reduced RA signaling. Alternatively spliced genes in Snrpb mutant somites were associated with post-transcriptional regulation, including chromatin modifiers. To test if RA pathway supplementation can rescue axial defects, we performed dietary RA supplementation; however, this failed to rescue mutant phenotypes, suggesting that p53 activation and chromatin dysregulation additionally contribute to disease pathogenesis. Together, these findings establish the first in vivo model of CCMS-associated axial skeletal abnormalities and indicate that Snrpb dysfunction disrupts the early specification of axial skeletal identity without overtly altering somite patterning.

developmental biology↗

bioRxiv2024

Identification of potential inhibitors against Inosine 5'-Monophosphate Dehydrogenase of Cryptosporidium parvum through an integrated in silico approach

The protozoan parasite Cryptosporidium, found in several vertebrates, including humans, is the source of the global infection known as cryptosporidiosis, which manifests as acute gastroenteritis, abdominal pain, and diarrhea. Although infections in certain individuals have been linked to other species, Cryptosporidium parvum is the main cause of illnesses in humans. Lactate Dehydrogenase, Inosine 5'-Monophosphate Dehydrogenase (IMPDH), and several other targets have been identified by the genome sequencing of C. parvum. Bioactive phytochemicals derived from nature have enormous potential as anti-cryptosporidiosis agents. The study aimed to identify new anti-cryptosporidial agents that work against the IMPDH of the parasite by using integrated in silico approaches. In this study, a total of 24 bioactive phytochemicals were screened virtually through molecular docking and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) analyses. Four lead compounds were identified, including Brevelin A (-8.9 kcal/mol), Vernodalin (-8.7 kcal/mol), Luteolin (-8.6 kcal/mol), and Pectolinarigenin (-8.1 kcal/mol), against the IMPDH protein (PDB ID: 4IXH) from the parasite. All the lead compounds had excellent pharmacokinetic and pharmacodynamic characteristics. The toxicity analysis showed satisfactory results with no major side effects. All of the selected compounds showed no violation of Lipinskis rules of five, indicating the possibility of oral bioavailability as potential drug candidates. In the majority of cases, target class prediction-identified enzymes, as well as investigational and experimental drugs, have been found to have structural similarities to the lead compounds. With significant biochemical interactions, all of the targeted phytochemical compounds have demonstrated excellent pharmacokinetics and better bioavailabilities. The findings strongly recommend in vitro experimental studies to aid in the development of novel therapeutics against Cryptosporidium parvum.

bioinformatics↗

bioRxiv2021

Snrpb, the gene mutated in CCMS, is haploinsufficient and required for proper morphogenesis and splicing

Heterozygous mutations in SNRPB, an essential core component of the five small ribonucleoprotein particles of the spliceosome, are responsible for Cerebrocostomandibular Syndrome (CCMS). We show that Snrpb heterozygous embryos arrest shortly after implantation. Additionally, heterozygous deletion of Snrpb in the developing brain and neural crest cells models craniofacial malformations found in CCMS, and results in death shortly after birth. RNAseq analysis of mutant heads prior to morphological defects revealed increased exon-skipping and intron-retention in association with increased 5 splice site strength. We found increased exon-skipping in negative regulators of the P53-pathway, increased levels of nuclear P53, P53-target genes. However, removing TrP53 in Snrpb heterozygous mutant neural crest cells did not completely rescue craniofacial development. We also found a small but significant increase in exon-skipping of several transcripts required for head and midface development, including Smad2 and Rere. Furthermore, mutant embryos exhibited ectopic or missing expression of Fgf8 and Shh, which are required to coordinate face and brain development. Thus, we propose that mis-splicing of transcripts that regulate P53-activity and craniofacial-specific genes both contribute to craniofacial malformations.

developmental biology↗

bioRxiv2019

Loss of function mutation of mouse Snap29 on a mixed genetic background phenocopy abnormalities found in CEDNIK and 22q11.2 Deletion Syndrome patients

Synaptosomal-associated protein 29 (SNAP29) is a member of the SNARE family of proteins involved in maintenance of various intracellular protein trafficking pathways. SNAP29 maps to the 22q11.2 region and is deleted in 90% of patients with 22q11.2 deletion syndrome (22q11.2DS). However, the contribution of hemizygosity of SNAP29 to developmental abnormalities in 22q11.2DS remains to be determined. Mutations in SNAP29 are responsible for the developmental syndrome called CEDNIK (cerebral dysgenesis, neuropathy, ichthyosis, and keratoderma). On an inbred C57Bl/6J genetic background, only the ichthyotic skin defect associated with CEDNIK was reported. In this study, we show that loss of function mutation of Snap29 on a mixed genetic background not only models skin abnormalities found in CEDNIK, but also phenocopy ophthalmological, neurological, and motor defects found in these patients and a subset of 22q11.2DS patients. Thus, our findings indicate that mouse models of human syndromes should be analyzed on a mixed genetic background. Our work also reveals an unanticipated requirement for Snap29 in male fertility, and support contribution of hemizygosity for SNAP29 to the phenotypic spectrum of abnormalities found in 22q11.2DS patients.

developmental biology↗