Hundreds of sterile α-motif (SAM) domains have predicted structural similarities and are reported to bind proteins, lipids, or RNAs. However, the majority of these domains have not been analyzed functionally. Previously, we demonstrated that a SAM domain-containing protein, SAMD14, promotes SCF/proto-oncogene c-Kit (c-Kit) signaling, erythroid progenitor function, and erythrocyte regeneration. Deletion of a Samd14 enhancer (Samd14-Enh), occupied by GATA2 and SCL/TAL1 transcription factors, reduces SAMD14 expression in bone marrow and spleen and is lethal in a hemolytic anemia mouse model. To rigorously establish whether Samd14-Enh deletion reduces anemia-dependent c-Kit signaling by lowering SAMD14 levels, we developed a genetic rescue assay in murine Samd14-Enh-/- primary erythroid precursor cells. SAMD14 expression at endogenous levels rescued c-Kit signaling. The conserved SAM domain was required for SAMD14 to increase colony-forming activity, c-Kit signaling, and progenitor survival. To elucidate the molecular determinants of SAM domain function in SAMD14, we substituted its SAM domain with distinct SAM domains predicted to be structurally similar. The chimeras were less effective than SAMD14 itself in rescuing signaling, survival, and colony-forming activities. Thus, the SAMD14 SAM domain has attributes that are distinct from other SAM domains and underlie SAMD14 function as a regulator of cellular signaling and erythrocyte regeneration.

中文翻译：

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细胞信号转导和存活的无菌α-基序结构域需求。

数百个无菌α-基序（SAM）域已预测出结构相似性，并据报道与蛋白质，脂质或RNA结合。但是，尚未对这些域中的大多数进行功能分析。以前，我们证明了包含SAM域的蛋白质SAMD14可以促进SCF /原癌基因c-Kit（c-Kit）信号传导，类红细胞祖细胞功能和红细胞再生。被GATA2和SCL / TAL1转录因子占据的Samd14增强子（Samd14-Enh）的缺失降低了SAMD14在骨髓和脾脏中的表达，并且在溶血性贫血小鼠模型中具有致命性。为了严格地确定Samd14-Enh缺失是否通过降低SAMD14水平来降低贫血依赖性c-Kit信号传导，我们在鼠类Samd14-Enh-/-红系前体细胞中开发了一种基因拯救试验。内源性水平的SAMD14表达挽救了c-Kit信号传导。SAMD14需要保守的SAM结构域来增加菌落形成活性，c-Kit信号传导和祖细胞存活。为了阐明SAMD14中SAM结构域功能的分子决定因素，我们将其SAM结构域替换为预测在结构上相似的不同SAM结构域。嵌合体在拯救信号传导，存活和集落形成活动方面不如SAMD14本身有效。因此，SAMD14 SAM结构域具有与其他SAM域不同的属性，并且在SAMD14的基础上起着细胞信号传导和红细胞再生的调节剂的作用。为了阐明SAMD14中SAM结构域功能的分子决定因素，我们将其SAM结构域替换为预测在结构上相似的不同SAM结构域。嵌合体在拯救信号传导，存活和集落形成活动方面不如SAMD14本身有效。因此，SAMD14 SAM结构域具有与其他SAM域不同的属性，并且在SAMD14的基础上起着细胞信号传导和红细胞再生的调节剂的作用。为了阐明SAMD14中SAM结构域功能的分子决定因素，我们将其SAM结构域替换为预测在结构上相似的不同SAM结构域。嵌合体在拯救信号传导，存活和集落形成活动方面不如SAMD14本身有效。因此，SAMD14 SAM结构域具有与其他SAM域不同的属性，并且在SAMD14的基础上起着细胞信号传导和红细胞再生的调节剂的作用。