Biology subjects

Sternberg, H.

Publications and source records attributed to Sternberg, H..

5 recordsLinked to original sources

bioRxiv2021

Differential Expression of α,β, and γ Protocadherin Isoforms During Differentiation, Aging, and Cancer

The cadherin family of cell surface glycoproteins plays a fundamental role in cell-cell recognition, thereby participating in diverse biological process such as embryonic morphogenesis and oncogenic transformation. The subset of clustered protocadherin (PCDH) genes generated from the , {beta}, and {gamma} loci, have been widely studied for their potential role in neuronal cell-cell recognition and neurogenesis, however their broader role in normal embryonic development and cancer has not been examined in detail. We utilized human embryonic stem (hES) cells to model early human development in vitro, comparing PCDH isoform transcription in diverse types of embryonic progenitors with normal adult-derived and cancer counterparts. Embryonic progenitors express genes from the and {beta} cluster at levels comparable to that seen in the CNS, while fetal and adult-derived cells express primarily from the {gamma} cluster. Replicative senescence left fibroblasts with markedly lower expression of all isoforms. We observe that an embryonic pattern of clustered protocadherin gene expression and associated CpG island methylation is commonly associated with cancer cell lines from diverse tissue types. The differential regulation of the , {beta}, and {gamma} loci coincide with alternate regions of DNA accessibility at CTCF binding sites and lamina-associated domains and CPL expression correlated with the expression of LMNA and LMNB1. These observations support a potential role for the differential regulation of genes within the clustered protocadherin locus in selective cell-cell adhesion during embryogenesis, regeneration, cancer and aging.

developmental biology↗

bioRxiv2021

Microtubule-associated ROP interactors both delimit and transduce ROP signaling and regulate microtubule dynamics

Evidence suggests that ICR proteins function as adaptors that mediate ROP signaling. Here, we studied the functions of ICR2 and its homologs ICR5 and ICR3. We showed that ICR2 is a microtubule-associated protein that regulates microtubule dynamics. ICR2 can retrieve activated ROPs from the plasma membrane, and it is recruited to a subset of ROP domains. Secondary cell wall pits in the metaxylem of icr2 and icr5 Arabidopsis single mutants and icr2/icr5 double and icr2/icr5/icr3 triple mutants were denser and larger than those in wild-type Col-0 seedlings, implicating these three ICRs in restriction of ROP function. The icr2 but not the icr5 mutants developed split root hairs further implicating ICR2 in restriction of ROP signaling. Taken together, our results show that ICR2, and likely also ICR5 and ICR3, have multiple functions as ROP effectors and as regulators of microtubule dynamics.

cell biology↗

bioRxiv2019

Character displacement within the breeding area questions reinforcement in Ficedula flycatchers

At present, studies of reinforcement should be focused on demonstrating how often this process occurs in nature and how important it is for speciation. Here we study the character displacement within the breeding area in the Pied Flycatcher to check the validity of the reinforcement in Ficedula flycatchers. We used point-referenced spatial data and a random forest to find the most important explanatory factors of the character displacement, and to reconstruct the phenotypic structure of the populations. The environmental temperature, and not the distance to sympatry, were proven to better describe the geographic pattern of the mean breeding plumage colour of the Pied Flycatcher populations. We conclude that ecologically distinct adaptations drive the morphological differentiation of the Old World flycatchers, and not reinforcement.

evolutionary biology↗

bioRxiv2018

The Ca2+ sensor protein CMI1 fine tunes root development, auxin distribution and responses

Signaling cross-talks between auxin, a regulator of plant development and Ca2+, a universal second messenger have been proposed to modulate developmental plasticity in plants. However, the underlying molecular mechanisms are largely unknown. Here we report that in Arabidopsis roots, auxin elicits specific Ca2+ signaling pattern that spatially coincide with the expression pattern of auxin-regulated genes. We identified the EF-hand protein CMI1 (Ca2+ sensor Modulator of ICR1) as an interactor of the ROP effector ICR1 (Interactor of Constitutively active ROP). CMI1 is monomeric in solution, changes its secondary structure at Ca2+ concentrations ranging from 10-9 to 10-8 M and its interaction with ICR1 is Ca2+ dependent, involving a conserved hydrophobic pocket. cmi1 mutants display an increased auxin response including shorter primary roots, longer root hairs, longer hypocotyls and altered lateral root formation while ectopic expression of CMI1 induces root growth arrest and reduced auxin responses at the root tip. When expressed alone, CMI1 is localized at the plasma membrane, the cytoplasm and in nuclei. Interaction of CMI1 and ICR1 results in exclusion of CMI1 from nuclei and suppression of the root growth arrest. CMI1 expression is directly upregulated by auxin while expression of auxin induced genes is enhanced in cmi1 concomitantly with repression of auxin induced Ca2+ increases in the lateral root cap and vasculature, indicating that CMI1 represses early auxin responses. Collectively, our findings identify a crucial function of Ca2+ signaling and CMI1 in root growth and suggest an auxin-Ca2+ regulatory feedback loop that fine tunes root development.

plant biology↗

bioRxiv2018

Delayed start of first-time breeding and non-breeders surplus in the Western Siberian population of the European Pied Flycatcher

Non-breeders are those sexually mature individuals that do not breed in a given reproductive cycle of a population. There is a widespread belief that the presence of non-breeders can affect the actual population dynamics, as well as the population responses to environmental change (Lee et al. 2017). Sternberg (1989), using demographic data, has shown that 83% and 62% of males and females, respectively, do not breed in the first year of life in the Lower Saxony (Germany) population of the European Pied Flycatcher (Ficedula hypoleuca). Later, with experimental removal of males, it has been proven that in the Lower Saxony and Moscow Region (Russia) populations, there are many non-breeding males (Sternberg et al. 2002). For the Netherlands population of the European Pied Flycatcher, the presence of a large number of non-breeders has been demonstrated using experimental removals for both males and females (Both et al. 2017). Here we have estimated the number of non-breeders in the Western Siberian population of the European Pied Flycatcher using demographic data (11 cohorts from 2001 to 2011 of birth) and experimental removal of males. We have shown that both males and females can start to breed at the age of one to five years. The proportion of non-breeders can be 59.5% and 68.5% for first-year males and females, respectively. We discuss the differences in the proportion of non-breeders between the Western Siberian and European populations of the European Pied Flycatcher, as well as factors affecting the number of non-breeders.

zoology↗