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Cloning and expression of a novel murine semaphorin with structural similarity to insect semaphorin I
1Department of Neurology, Washington University, St. Louis, Missouri 63110, USA.
Abstract:
We describe a novel semaphorin family member, Sema VIa, with 25-36% sequence identity at the amino acid level in the semaphorin domain to previously published mouse homologues. This novel family member shares considerable homology with the best characterized murine semaphorin, Sema III (also known as SemD), at the 5' end but is divergent from Sema III near the 3' end because it contains a putative transmembrane domain. Remarkably, of the known semaphorins, Sema VIa bears the greatest structural similarity to insect Sema I, although it contains a much larger intracellular domain. We propose, therefore, that Sema VIa is the prototype of a new class (class VI) of semaphorins. In order to gain insights into potential functions of Sema VIa, we have compared mRNA expression of Sema VIa to that of Sema III during development. In the nervous system, Sema VIa is expressed in strikingly localized and transient patterns that are markedly different from those of Sema III. Interestingly, Sema VIa and Sema III frequently exhibit complementary or adjacent loci of expression. We suggest that Sema VIa may be important to nervous system development via a mechanism that involves cell-cell communication.
Insights
Researchers identified a new semaphorin, Sema VIa, structurally similar to insect Sema I. Its distinct expression patterns suggest a role in nervous system development through cell-cell communication.
Area of Science:
- Molecular Biology
- Neuroscience
- Genetics
Background:
- Semaphorins are a family of secreted and transmembrane proteins involved in cell signaling.
- Previous studies have characterized several semaphorin family members, primarily in mice.
- Understanding novel semaphorins is crucial for deciphering complex developmental processes.
Purpose of the Study:
- To characterize a novel semaphorin family member, designated Sema VIa.
- To investigate the structural and expression patterns of Sema VIa in comparison to known semaphorins.
- To elucidate the potential role of Sema VIa in nervous system development.
Main Methods:
- Sequence analysis to determine homology with known semaphorins.
- Comparison of structural features, including transmembrane domains.
- Messenger RNA (mRNA) expression analysis during development.
- Comparative analysis of Sema VIa and Sema III expression patterns in the nervous system.
Main Results:
- Sema VIa exhibits 25-36% amino acid sequence identity in the semaphorin domain to mouse homologues.
- Sema VIa shares homology with Sema III but possesses a unique putative transmembrane domain.
- Sema VIa shows structural similarity to insect Sema I, suggesting a new class (class VI) of semaphorins.
- Sema VIa displays localized and transient mRNA expression patterns in the developing nervous system, distinct from Sema III.
- Sema VIa and Sema III often show complementary or adjacent expression loci.
Conclusions:
- Sema VIa represents a novel class (class VI) of semaphorins.
- The distinct expression patterns of Sema VIa suggest a specific role in nervous system development.
- Sema VIa may mediate its function through cell-cell communication pathways.